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EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH

ALICE-PUBLIC-2017-005

© 2017 CERN for the benefit of the ALICE Collaboration.

Reproduction of this article or parts of it is allowed as specified in the CC-BY-4.0 license.

The ALICE definition of primary particles

ALICE Collaboration*

Abstract

In this public note, we specify what we mean by the term primary particle. The definition is moti-

vated by what is in principle measurable by ALICE and that event generators and other such theoret-

ical considerations must be able to reproduce the same requirements. To this end, we also provide a

Rivet projection to be used in ALICE Rivet analyses.

*See Appendix E for the list of collaboration members

2

ALICE Collaboration

Contents

1 The definition

3

1.1 Variationsofthedefinition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2 Some explanatory comments

3

2.1 Lifetimeconsiderations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.2 Decayradiusconsiderations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2.3 Decay product considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3 Algorithmic description

5

4 Definitions used in the past and by other collaborations

5

4.1 ALICEdefinitionpriorto2017 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4.2 ALICEdefinitionpriorto2013 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

4.3 LPCC MB+UE working group’s definition of primary particles . . . . . . . . . . . . . . 7

4.4 CMSdefinitionofprimaryparticles . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

4.5 ATLASdefinitionofprimaryparticles . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

5 Summary

8

A Table of lifetimes

11

B LATEX code of the definition

16

C Rivet projection

17

D Code

21

E ALICE Collaboration

23

The ALICE definition of primary particles

3

1 The definition

The following sentence constitutes the ALICE definition what we consider a primary particle.

A primary particle is a particle with a mean proper lifetime τ larger than 1cm/c, which is

either a) produced directly in the interaction, or b) from decays of particles with τ smaller

than 1 cm/c, restricted to decay chains leading to the interaction.

In the sentence above and else where in this note, except if otherwise indicated, the word “interaction”

refers the interaction between the colliding partners.

All particles that do not meet the requirements are not primary particles and are therefore dubbed sec-

ondary particles.

1.1 Variations of the definition

Alternatively, if the analysis presented concerns only charged, primary particles, we will write

A primary, charged particle is a charged particle with a mean proper lifetime τ larger than

1cm/c, which is either a) produced directly in the interaction, or b) from decays of particles

with τ smaller than 1cm/c, restricted to decay chains leading to the interaction.

In some cases, we present measurements of identified particles that are not included in the above defini-

tion of a primary particle e.g., the π0. In such cases, the definition of what we mean by a primary particle

of type X can be replaced by

A primary X is an X, which is either a) produced directly in the interaction; or b) from

decays of particles with mean proper lifetime τ smaller than 1cm/c, restricted to decay

chains leading to the interaction.

Finally, in some manuscripts, the caveat “restricted to decay chains leading to the interaction” may be

cumbersome. In those cases, we may write

A primary particle is a particle with a mean proper lifetime τ larger than 1cm/c, which is

either a) produced directly in the interaction, or b) from decays of particles with τ smaller

than 1 cm/c, excluding particles produced in interactions with material.

It should be understood that the above sentence and the sentence given at the top of this Section are

entirely equivalent and does not include or exclude more or less particles. The choice of exact phrase

used in a given manuscript is a matter of preference.

2 Some explanatory comments

2.1 Lifetime considerations

The definition above requires that a particle is long-lived i.e., lives long enough that it may in principle

be detected by the ALICE detectors. By long-lived particle, we mean a particle that has a mean proper

lifetime larger than 1cm/c. The particle species that fulfill this requirement according to the Particle

Data Group [1], are given in Tab. 1. The particle species with the longest mean proper lifetime that falls

outside of this cut is the B+ with τ = 0.049cm/c (see also Appendix A for a full list).

4

ALICE Collaboration

Width Γ

Mean proper lifetime τ

Specie

(GeV)

(ps)

(cm/c)

p+

0

∞

∞

γ

0

∞

∞

K0

0

∞

∞

e−

0

∞

∞

n

7.478×10−28

8.861×10+14

2.656×10+13

µ−

2.996×10−19

2.212×10+06

6.63×10+04

K0

L

1.287×10−17

5.148×10+04

1543

π+

2.528×10−17

2.621×10+04

785.7

K+

5.317×10−17

1.246×10+04

373.6

Ξ

0

2.27×10−15

291.9

8.751

Λ

2.501×10−15

264.9

7.943

Ξ

−

4.02×10−15

164.8

4.941

Σ

−

4.45×10−15

148.9

4.464

K0

S

7.351×10−15

90.14

2.702

Ω

−

8.071×10−15

82.1

2.461

Σ

+

8.209×10−15

80.72

2.42

Table 1: Width (Γ) and mean proper lifetime (τ) of long-lived particles, sorted by descending mean proper lifetime

[1]. Here, a zero width or “∞” mean proper lifetime signifies undetermined values and are presumed small or large,

respectively.

2.2 Decay radius considerations

The choice of the mean proper lifetime cut–off of 1cm/c is motivated by the capability of the ALICE

detectors. That is, a particle produced in a decay close to the interaction can not be distinguished from

particles produced directly in the interaction. As a rule-of-thumb a particle from decay can be unambigu-

ously be identified as a non-primary particle when the decay occurs on average more than 1 cm away from

the interaction. Furthermore, particles produced by inelastic collisions with the ALICE beam-pipe, with

a radius of 2.98 cm [2]1, sets a limit to how close to the interaction one can resolve decay vertices.

The mean proper lifetime of a given particle species defines the mean lifetime of particles of that species

in the rest frame of the particle. In the laboratory frame, the average decay length is given by2

λlab = τβγ = τ

p

m0

(1)

and as such depends on the momentum of the particle. Considering the longest lived particle species

with a τ < 1cm/c, the B+ with τ = 0.049cm/c and mo = 5.2793GeV, we find that a particle of this

type with a momentum of 10GeV/c may on average travel ≈ 1mm, but would require a momentum of

> 350GeV/c to live long enough to decay outside of the ALICE beam-pipe. For the less heavy D+ to

decay outside the ALICE beam-pipe it would need a momentum larger than 180GeV/c. For the shortest

lived particle with τ > 1cm/c, the Σ+, only a momentum of ≈ 2GeV/c would be needed.

2.3 Decay product considerations

The definition requires for a particle to be primary, that there are no long-lived particles in the decay

chain that leads to that particle. This is illustrated in Fig. 1. For the K0

S and Ξ− chains only the initial

1In Run 3 of the LHC, the beam-pipe will be replaced with a smaller radius between 1.72cm and 1.92 cm [3].

2The convention adopted by the ALICE collaboration is to set the speed of light c = 1 and hence leave it out of equations,

except in units of measure where c is explicitly given.

The ALICE definition of primary particles

5

K0

S

π−

π+

Ξ

−

π−

Λ

π−

p

B0

D−

ρ+

K∗(892)

π−

K+

π−

π0

π+

γ

γ

Interaction

Figure 1: Various decays. Particles defined as primaries are marked in red. In both the Ξ− and K0

S decays, the

initial particles are considered primary, since these particles are long-lived, while all the decay products are not

considered primaries. In the B0 decay chain, the π’s, γ’s, and the K+ are all primary since they are the first

long-lived particle in the decay chain leading back to the interaction.

particles are primaries because τ > 1cm/c. In the B0 branch the charged π’s are primaries, since when

tracking back to the initial B0 we meet no long lived particles. Similar considerations applies to the 2

γ’s and the K+. That is, we must be able to track back to the interaction and not find any long lived

particles, but without considering branches of the decay tree that do not end up in the particle we are

considering. Also, we require that all production processes in the chain are decays — that is, we exclude

chains that contain inelastic interactions with material, hadronic interactions, and other such production

mechanisms.

3 Algorithmic description

Figure 2 illustrates the algorithm used to determine if a given particle p is primary or not. If p is neither

long-lived nor produced in a decay, nor directly in the collision, it is certainly not a primary. Next, we

check to see if p has a mother particle m. If no such mother particle exists, we have a primary. If we can

find an ancestor we step through each successive ancestor and check if the ancestor is either long-lived

or neither from a decay nor from the interaction, then the particle under consideration p is not a primary.

If we can continue this search back to the interaction i.e., we cannot find any more ancestors, then we do

have a primary.

The algorithm shown in Fig. 2 is implemented into the ALICE simulation framework and is consistently

used throughout all analysis that need to distinguish between primary and non-primary particles. The

code is reproduced in Appendix D.

4 Definitions used in the past and by other collaborations

4.1 ALICE definition prior to 2017

Primary [charged] particles are defined as prompt [charged] particles produced in the colli-

sion, including their decay products, but excluding products of weak decays of muons and

light flavour hadrons. Secondary [charged] particles are all other particles observed in the

experiment e.g., particles produced through interactions with material and products of weak

decays. [4]

Parenthesis added.

The primary charged particles are defined as prompt particles produced in the collision in-

cluding all decay products, except products from weak decays of light flavor hadrons and of

muons. [5]

The above two definitions of (charged) primary particles has formed the basis in many ALICE publi-

cations so far. The definition can be construed to mean that both prompt (i.e., produced directly in the

6

ALICE Collaboration

Is p

long-lived?

For

particle p

Is p from

decay or

interaction?

Find mother

particle

m of p

Does m

exist?

Is m

long-lived

Is m from

decay or

interaction?

Find mother

m of m

Does m

exists

Let m = m

p is

primary

p is not

primary

no

yes

no

yes

no

No ancestors

yes

yes

no

no

yes

no

yes

loop

Figure 2: Flow chart of deciding if a given particle is primary or not.

interaction) particles and the decay products counts as primary particles, thus leading to a double count

of particles. For example, in this reading of the above definitions, the D− decay in Fig. 1 would count

as 5 (rather than 3) primary particles. Clearly, this is not the intent of the definition, and operationally

no such double counting ever took place. The wording of the definition is the cause of the confusion.

The current definition remedies the misunderstanding by explicitly requiring where in the decay chain

primary particles may originate from.

The second part of the definition, which stipulates that decay products from weak decays of light flavour

hadrons and muons are not considered primaries is entirely equivalent to current definitions requirement

of mean proper lifetime larger than 1cm/c and that possible parent particles must have a mean proper

lifetime smaller than 1cm/c. The known light flavour hadron with the shortest mean proper lifetime is

the Σ+ with a τ = 2.42cm/c, and as such, under the current and previous definition none of its decay

The ALICE definition of primary particles

7

products can never be primary.

The current definition, and the 3 quoted above are therefore entirely equivalent though the current defi-

nition clarifies the exact conditions and is therefore used by ALICE.

4.2 ALICE definition prior to 2013

Primary particles are defined as prompt particles produced in the collisions, including all

decay products, with the exception of those from weak decays of strange particles. [6]

We define primary particles as prompt particles produced in the collision, including decay

products, except those from weak decays of strange particles. [7]

Relative to the definitions presented in Section 4.1, these formulations would include decay products of

µ± and π±. This was an oversight on the part of the formulation, since the operational definition has

remained constant between 2013 and 2016. The reason for the oversight was that µ± and π± are so long

lived that they rarely decay within the ALICE acceptance, and was simply ignored by the definition.

Bearing that oversight in mind, this definition of primary particles is entirely consistent with the current

and those listed in Section 4.1.

4.3 LPCC MB+UE working group’s definition of primary particles

We reiterated the definition of “charged particle” used in the common plots: this includes

hadrons and leptons, with mean lifetime τ > 0.3×10−10 s, produced directly or from decays

of shorter-lifetime particles. No particle level correction (e.g. no correction to subtract

Dalitz decays) [is used]. [8]

Parenthesis added.

This definition adopted by the LHC Physics Center at CERN Minimum Bias and Underlying Event

working group is identical to the definition adopted by ALICE.

4.4 CMS definition of primary particles

Primary [charged] particles are defined as all [charged] particles produced in the interaction

with a proper lifetime τ of greater than 1cm, including the products of strong and elec-

tromagnetic decays, but excluding particles originating from secondary interactions. The

products of weak decays are only considered primary particles if they are the products of a

particle produced in the interaction with a τ of less than 1cm. [9]

Parenthesis added.

This definition can be construed to mean, that in the decay Λ → π− + p we would count 3 particles

(since all three species have a mean proper life time larger than 1cm/c. However, the last part of the

definition, which stipulates that mother particles in weak decays must have τ < 1cm/c for the decay

products to be considered primary, rules this out and the definition only counts 1 particle, albeit it may

not be immediately obvious to the reader.

The definition adopted by the ALICE collaboration explicitly rules out double counting. The above

definition from the CMS collaboration and the one adopted by the ALICE collaboration are otherwise

equivalent.

8

ALICE Collaboration

4.5 ATLAS definition of primary particles

A primary [charged] particle is defined as a [charged] particle with a mean lifetime τ >

300ps[≈ 9cm/c], which is either directly produced in pp interactions or from decays of

directly produced particles with τ < 30ps[≈ 0.9cm/c]; particles produced from decays of

particles with τ > 30ps[≈ 0.9cm/c] are considered as secondary particles and are thus ex-

cluded. [10]

Parenthesis and τ in length units added.

In this definition, if a particle has a mean proper lifetime between 30 and 300ps (or 0.9 to 9cm/c), it

is not considered a primary particle, which excludes all hyperons and K0

S, nor are the decay products of

these particles. If the particle has a lifetime shorter than 30ps it is not a primary, but it decay products

may be e.g., a prompt D+ decaying to N+π is counted as a single primary particle. Similarly all charmed

baryons and mesons cannot be primary but their decay products may.

This definition obviously differs from the definition adopted by the ALICE collaboration, in particular

for hyperons and K0

S which are never considered primary unless produced in the decay of much shorter

lived particles. In the ALICE definition, prompt hyperons and K0

Sare considered primaries.

5 Summary

The definition presented in Section 1 provides a clear method to distinguish what ALICE means by

“primary”. Operationally the definition is equivalent to previous definitions used, but has the advantage

of clarity and reproducability.

Acknowledgements

The ALICE Collaboration would like to thank all its engineers and technicians for their invaluable con-

tributions to the construction of the experiment and the CERN accelerator teams for the outstanding

performance of the LHC complex. The ALICE Collaboration gratefully acknowledges the resources and

support provided by all Grid centres and the Worldwide LHC Computing Grid (WLCG) collaboration.

The ALICE Collaboration acknowledges the following funding agencies for their support in building and

running the ALICE detector: A. I. Alikhanyan National Science Laboratory (Yerevan Physics Institute)

Foundation (ANSL), State Committee of Science and World Federation of Scientists (WFS), Arme-

nia; Austrian Academy of Sciences and Nationalstiftung für Forschung, Technologie und Entwicklung,

Austria; Ministry of Communications and High Technologies, National Nuclear Research Center, Azer-

baijan; Conselho Nacional de Desenvolvimento Cientıfico e Tecnológico (CNPq), Universidade Federal

do Rio Grande do Sul (UFRGS), Financiadora de Estudos e Projetos (Finep) and Fundaç˜ao de Am-

paro `a Pesquisa do Estado de S˜ao Paulo (FAPESP), Brazil; Ministry of Science & Technology of China

(MSTC), National Natural Science Foundation of China (NSFC) and Ministry of Education of China

(MOEC) , China; Ministry of Science, Education and Sport and Croatian Science Foundation, Croatia;

Ministry of Education, Youth and Sports of the Czech Republic, Czech Republic; The Danish Council

for Independent Research — Natural Sciences, the Carlsberg Foundation and Danish National Research

Foundation (DNRF), Denmark; Helsinki Institute of Physics (HIP), Finland; Commissariat `a l’Energie

Atomique (CEA) and Institut National de Physique Nucléaire et de Physique des Particules (IN2P3) and

Centre National de la Recherche Scientifique (CNRS), France; Bundesministerium für Bildung, Wis-

senschaft, Forschung und Technologie (BMBF) and GSI Helmholtzzentrum für Schwerionenforschung

GmbH, Germany; General Secretariat for Research and Technology, Ministry of Education, Research

and Religions, Greece; National Research, Development and Innovation Office, Hungary; Department

of Atomic Energy Government of India (DAE) and Council of Scientific and Industrial Research (CSIR),

New Delhi, India; Indonesian Institute of Science, Indonesia; Centro Fermi - Museo Storico della Fisica

The ALICE definition of primary particles

9

e Centro Studi e Ricerche Enrico Fermi and Istituto Nazionale di Fisica Nucleare (INFN), Italy; Institute

for Innovative Science and Technology , Nagasaki Institute of Applied Science (IIST), Japan Society for

the Promotion of Science (JSPS) KAKENHI and Japanese Ministry of Education, Culture, Sports, Sci-

ence and Technology (MEXT), Japan; Consejo Nacional de Ciencia (CONACYT) y Tecnologıa, through

Fondo de Cooperación Internacional en Ciencia y Tecnologıa (FONCICYT) and Dirección General de

Asuntos del Personal Academico (DGAPA), Mexico; Nederlandse Organisatie voor Wetenschappelijk

Onderzoek (NWO), Netherlands; The Research Council of Norway, Norway; Commission on Science

and Technology for Sustainable Development in the South (COMSATS), Pakistan; Pontificia Universi-

dad Católica del Perú, Peru; Ministry of Science and Higher Education and National Science Centre,

Poland; Korea Institute of Science and Technology Information and National Research Foundation of

Korea (NRF), Republic of Korea; Ministry of Education and Scientific Research, Institute of Atomic

Physics and Romanian National Agency for Science, Technology and Innovation, Romania; Joint In-

stitute for Nuclear Research (JINR), Ministry of Education and Science of the Russian Federation and

National Research Centre Kurchatov Institute, Russia; Ministry of Education, Science, Research and

Sport of the Slovak Republic, Slovakia; National Research Foundation of South Africa, South Africa;

Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear (CEADEN), Cubaenergıa, Cuba, Ministerio

de Ciencia e Innovacion and Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas

(CIEMAT), Spain; Swedish Research Council (VR) and Knut & Alice Wallenberg Foundation (KAW),

Sweden; European Organization for Nuclear Research, Switzerland; National Science and Technology

Development Agency (NSDTA), Suranaree University of Technology (SUT) and Office of the Higher Ed-

ucation Commission under NRU project of Thailand, Thailand; Turkish Atomic Energy Agency (TAEK),

Turkey; National Academy of Sciences of Ukraine, Ukraine; Science and Technology Facilities Coun-

cil (STFC), United Kingdom; National Science Foundation of the United States of America (NSF) and

United States Department of Energy, Office of Nuclear Physics (DOE NP), United States of America.

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10

ALICE Collaboration

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The ALICE definition of primary particles

11

A Table of lifetimes

Width Γ

Mean proper lifetime τ

Specie

(GeV)

(ps)

(cm/c)

p+

≪ 10−29

≫ 10+15

≫ 10+14

γ

≪ 10−29

≫ 10+15

≫ 10+14

K0

≪ 10−29

≫ 10+15

≫ 10+14

e−

≪ 10−29

≫ 10+15

≫ 10+14

n

7.478×10−28

8.861×10+14

2.656×10+13

µ−

2.996×10−19

2.212×10+06

6.63×10+04

K0

L

1.287×10−17

5.148×10+04

1543

π+

2.528×10−17

2.621×10+04

785.7

K+

5.317×10−17

1.246×10+04

373.6

Ξ

0

2.27×10−15

291.9

8.751

Λ

2.501×10−15

264.9

7.943

Ξ

−

4.02×10−15

164.8

4.941

Σ

−

4.45×10−15

148.9

4.464

K0

S

7.351×10−15

90.14

2.702

Ω

−

8.071×10−15

82.1

2.461

Σ

+

8.209×10−15

80.72

2.42

B+

4.018×10−13

1.649

0.04944

Ω

−

b

4.2×10−13

1.578

0.0473

Ξ

−

b

4.22×10−13

1.57

0.04707

B0

4.33×10−13

1.53

0.04588

B0

s

4.359×10−13

1.52

0.04557

Λb

4.49×10−13

1.476

0.04424

Ξ

0

b

4.5×10−13

1.472

0.04414

D+

6.33×10−13

1.047

0.03138

B+

c

1.298×10−12

0.5105

0.0153

D+

s

1.317×10−12

0.5031

0.01508

Ξ

+

c

1.49×10−12

0.4447

0.01333

D0

1.605×10−12

0.4128

0.01238

τ−

2.267×10−12

0.2923

0.008762

Λ

+

c

3.3×10−12

0.2008

0.00602

Ξ

0

c

5.9×10−12

0.1123

0.003367

Ω

0

c

9.6×10−12

0.06902

0.002069

π0

7.73×10−09

8.572×10−05

2.57×10−06

η

1.31×10−06

5.058×10−07

1.516×10−08

Σ

0

8.9×10−06

7.445×10−08

2.232×10−09

ϒ

(3S)

2.03×10−05

3.264×10−08

9.785×10−10

ϒ

(2S)

3.2×10−05

2.071×10−08

6.208×10−10

ϒ

(1S)

5.4×10−05

1.227×10−08

3.679×10−10

D∗+

(2010)

8.34×10−05

7.945×10−09

2.382×10−10

J/ψ0

(1S)

9.29×10−05

7.132×10−09

2.138×10−10

η

(958)

0.000197 3.363×10−09

1.008×10−10

ψ

(2S)

0.000296 2.239×10−09

6.711×10−11

hc

(1P)

0.0007 9.466×10−10

2.838×10−11

χ0

c1

(1P)

0.00084 7.888×10−10

2.365×10−11

D+

s1

(2536)

0.00092 7.202×10−10

2.159×10−11

Λ

+

c

(2625)

0.00097 6.831×10−10

2.048×10−11

B∗

s2

(5840)

0.00147 4.508×10−10

1.351×10−11

Σ

0

c

(2455)

0.00183 3.621×10−10

1.085×10−11

Σ

++

c

(2455)

0.00189 3.506×10−10

1.051×10−11

D∗+

s

0.0019 3.487×10−10

1.045×10−11

χ0

c2

(1P)

0.00193 3.433×10−10

1.029×10−11

Table A.1: Width (Γ), and mean proper lifetime (τ) of various particles,

sorted by descending lifetime

12

ALICE Collaboration

Width Γ

Mean proper lifetime τ

Specie

(GeV)

(ps)

(cm/c)

D∗0

(2007)

0.0021 3.155×10−10

9.459×10−12

Λ

+

c

(2595)

0.0026 2.548×10−10

7.64×10−12

Ξ

+

c

(2645)

0.0026 2.548×10−10

7.64×10−12

Ξ

0

(1690)

0.003 2.209×10−10

6.621×10−12

Ξ

−

(1690)

0.003 2.209×10−10

6.621×10−12

D+

s1

(2460)

0.0035 1.893×10−10

5.676×10−12

Ξ

+

c

(2815)

0.0035 1.893×10−10

5.676×10−12

D

∗+

s0

(2317)

0.0038 1.744×10−10

5.227×10−12

ϕ

(1020)

0.004266 1.553×10−10

4.656×10−12

Σ

+

c

(2455)

0.0046

1.44×10−10

4.318×10−12

Σ

−

b

0.0049 1.352×10−10

4.054×10−12

Ξ

0

c

(2645)

0.0055 1.205×10−10

3.612×10−12

Λ

+

c

(2880)

0.0058 1.142×10−10

3.425×10−12

Ξ

0

c

(2815)

0.0065 1.019×10−10

3.056×10−12

Σ

∗−

b

0.0075 8.835×10−11

2.649×10−12

ω

(782)

0.00849 7.805×10−11

2.34×10−12

Ξ

0

(1530)

0.0091 7.281×10−11

2.183×10−12

Σ

+

b

0.0097 6.831×10−11

2.048×10−12

Ξ

−

(1530)

0.0099 6.693×10−11

2.007×10−12

χ0

c0

(1P)

0.0105 6.311×10−11

1.892×10−12

ηc

(2S)

0.0113 5.864×10−11

1.758×10−12

Σ

∗+

b

0.0115 5.762×10−11

1.727×10−12

Ξ

+

c

(2790)

0.012 5.522×10−11

1.655×10−12

Σ

++

c

(2520)

0.01478 4.483×10−11

1.344×10−12

Ξ

0

c

(2790)

0.015 4.417×10−11

1.324×10−12

Σ

0

c

(2520)

0.0153 4.331×10−11

1.298×10−12

Λ

(1520)

0.0156 4.247×10−11

1.273×10−12

D

∗+

s2

(2573)

0.0169 3.921×10−11

1.175×10−12

Σ

+

c

(2520)

0.017 3.898×10−11

1.168×10−12

Ξ

−

(2030)

0.02 3.313×10−11

9.932×10−13

Ξ

0

(2030)

0.02 3.313×10−11

9.932×10−13

ϒ

(4S)

0.0205 3.232×10−11

9.69×10−13

Ξ

0

(1820)

0.024 2.761×10−11

8.277×10−13

Ξ

−

(1820)

0.024 2.761×10−11

8.277×10−13

χ0

c2

(2P)

0.024 2.761×10−11

8.277×10−13

f1

(1285)

0.0241 2.749×10−11

8.243×10−13

B∗

2

(5747)

0.0242 2.738×10−11

8.208×10−13

B

∗+

2

(5747)

0.0242 2.738×10−11

8.208×10−13

ψ

(3770)

0.0272 2.436×10−11

7.303×10−13

D0

1

(2420)

0.0317

2.09×10−11

6.266×10−13

ηc

(1S)

0.0318 2.084×10−11

6.247×10−13

Λ

(1670)

0.035 1.893×10−11

5.676×10−13

Σ

+

(1385)

0.036 1.841×10−11

5.518×10−13

Σ

0

(1385)

0.036 1.841×10−11

5.518×10−13

Σ

−

(1385)

0.0394 1.682×10−11

5.042×10−13

D

∗+

2

(2460)

0.0467 1.419×10−11

4.254×10−13

K∗

(892)

0.0474 1.398×10−11

4.191×10−13

D∗

2

(2460)

0.0477 1.389×10−11

4.164×10−13

Λ

(1405)

0.0505 1.312×10−11

3.934×10−13

K∗+

(892)

0.0508 1.304×10−11

3.91×10−13

η

(1405)

0.051 1.299×10−11

3.895×10−13

ϒ

(10860)

0.054 1.227×10−11

3.679×10−13

f1

(1420)

0.0549 1.207×10−11

3.618×10−13

Table A.1: Width (Γ), and mean proper lifetime (τ) of various particles,

sorted by descending lifetime

The ALICE definition of primary particles

13

Width Γ

Mean proper lifetime τ

Specie

(GeV)

(ps)

(cm/c)

η

(1295)

0.055 1.205×10−11

3.612×10−13

Ω

−

(2250)

0.055 1.205×10−11

3.612×10−13

Ξ

0

(1950)

0.06 1.104×10−11

3.311×10−13

f0

(980)

0.06 1.104×10−11

3.311×10−13

Λ

(1690)

0.06 1.104×10−11

3.311×10−13

Ξ

−

(1950)

0.06 1.104×10−11

3.311×10−13

Σ

0

(1670)

0.06 1.104×10−11

3.311×10−13

Σ

+

(1670)

0.06 1.104×10−11

3.311×10−13

Σ

−

(1670)

0.06 1.104×10−11

3.311×10−13

ϒ

(11020)

0.061 1.086×10−11

3.256×10−13

ψ

(4415)

0.062 1.069×10−11

3.204×10−13

ψ

(4160)

0.07 9.466×10−12

2.838×10−13

f2

(1525)

0.073 9.077×10−12

2.721×10−13

a0

(980)

0.075 8.835×10−12

2.649×10−13

a+

0

(980)

0.075 8.835×10−12

2.649×10−13

ψ

(4040)

0.08 8.283×10−12

2.483×10−13

Λ

(1820)

0.08 8.283×10−12

2.483×10−13

η

(1475)

0.085 7.795×10−12

2.337×10−13

ϕ3

(1850)

0.087 7.616×10−12

2.283×10−13

K+

1

(1270)

0.09 7.362×10−12

2.207×10−13

Σ

0

(1750)

0.09 7.362×10−12

2.207×10−13

Σ

+

(1750)

0.09 7.362×10−12

2.207×10−13

Σ

−

(1750)

0.09 7.362×10−12

2.207×10−13

K0

1

(1270)

0.09 7.362×10−12

2.207×10−13

Λ

(1830)

0.095 6.975×10−12

2.091×10−13

K

∗+

2

(1430)

0.0985 6.727×10−12

2.017×10−13

Σ

0

(1660)

0.1 6.626×10−12

1.986×10−13

Σ

−

(1660)

0.1 6.626×10−12

1.986×10−13

N+

(1710)

0.1 6.626×10−12

1.986×10−13

N

(1710)

0.1 6.626×10−12

1.986×10−13

Λ

(1890)

0.1 6.626×10−12

1.986×10−13

Σ

+

(1660)

0.1 6.626×10−12

1.986×10−13

a+

2

(1320)

0.107 6.193×10−12

1.856×10−13

a2

(1320)

0.107 6.193×10−12

1.856×10−13

K∗

2

(1430)

0.109 6.079×10−12

1.822×10−13

f0

(1500)

0.109 6.079×10−12

1.822×10−13

N+

(1520)

0.115 5.762×10−12

1.727×10−13

N

(1520)

0.115 5.762×10−12

1.727×10−13

∆

++

(1232)

0.117 5.663×10−12

1.698×10−13

∆

+

(1232)

0.117 5.663×10−12

1.698×10−13

∆

0

(1232)

0.117 5.663×10−12

1.698×10−13

∆

−

(1232)

0.117 5.663×10−12

1.698×10−13

Σ

0

(1915)

0.12 5.522×10−12

1.655×10−13

Σ

+

(1775)

0.12 5.522×10−12

1.655×10−13

Σ

0

(1775)

0.12 5.522×10−12

1.655×10−13

Σ

+

(1915)

0.12 5.522×10−12

1.655×10−13

Σ

−

(1775)

0.12 5.522×10−12

1.655×10−13

Σ

−

(1915)

0.12 5.522×10−12

1.655×10−13

N+

(1680)

0.13 5.097×10−12

1.528×10−13

N

(1680)

0.13 5.097×10−12

1.528×10−13

f0

(1710)

0.139 4.767×10−12

1.429×10−13

∆

+

(1620)

0.14 4.733×10−12

1.419×10−13

∆

++

(1620)

0.14 4.733×10−12

1.419×10−13

Table A.1: Width (Γ), and mean proper lifetime (τ) of various particles,

sorted by descending lifetime

14

ALICE Collaboration

Width Γ

Mean proper lifetime τ

Specie

(GeV)

(ps)

(cm/c)

∆

−

(1620)

0.14 4.733×10−12

1.419×10−13

∆

0

(1620)

0.14 4.733×10−12

1.419×10−13

N+

(1650)

0.14 4.733×10−12

1.419×10−13

N

(1650)

0.14 4.733×10−12

1.419×10−13

b1

(1235)

0.142 4.666×10−12

1.399×10−13

b+

1

(1235)

0.142 4.666×10−12

1.399×10−13

ρ0

(770)

0.1491 4.444×10−12

1.332×10−13

ρ+

(770)

0.1491 4.444×10−12

1.332×10−13

Λ

(1600)

0.15 4.417×10−12

1.324×10−13

ϕ

(1680)

0.15 4.417×10−12

1.324×10−13

Λ

(1810)

0.15 4.417×10−12

1.324×10−13

N+

(1700)

0.15 4.417×10−12

1.324×10−13

N

(1700)

0.15 4.417×10−12

1.324×10−13

N+

(1675)

0.15 4.417×10−12

1.324×10−13

N

(1675)

0.15 4.417×10−12

1.324×10−13

N+

(1535)

0.15 4.417×10−12

1.324×10−13

N

(1535)

0.15 4.417×10−12

1.324×10−13

f2

(2300)

0.15 4.417×10−12

1.324×10−13

K∗

3

(1780)

0.159 4.167×10−12

1.249×10−13

K

∗+

3

(1780)

0.159 4.167×10−12

1.249×10−13

ρ+

3

(1690)

0.161 4.116×10−12

1.234×10−13

ρ0

3

(1690)

0.161 4.116×10−12

1.234×10−13

ω3

(1670)

0.168 3.944×10−12

1.182×10−13

K0

1

(1400)

0.174 3.808×10−12

1.142×10−13

K+

1

(1400)

0.174 3.808×10−12

1.142×10−13

Σ

−

(2030)

0.18 3.681×10−12

1.104×10−13

Σ

0

(2030)

0.18 3.681×10−12

1.104×10−13

Σ

+

(2030)

0.18 3.681×10−12

1.104×10−13

η2

(1645)

0.181 3.661×10−12

1.097×10−13

K+

2

(1770)

0.186 3.562×10−12

1.068×10−13

K0

2

(1770)

0.186 3.562×10−12

1.068×10−13

f2

(1270)

0.1867 3.549×10−12

1.064×10−13

K

∗+

4

(2045)

0.198 3.346×10−12

1.003×10−13

K∗

4

(2045)

0.198 3.346×10−12

1.003×10−13

Λ

(2100)

0.2 3.313×10−12

9.932×10−14

f2

(2010)

0.2 3.313×10−12

9.932×10−14

Λ

(2110)

0.2 3.313×10−12

9.932×10−14

π0

(1800)

0.208 3.186×10−12

9.55×10−14

π+

(1800)

0.208 3.186×10−12

9.55×10−14

ω

(1420)

0.215 3.082×10−12

9.239×10−14

Σ

+

(1940)

0.22 3.012×10−12

9.029×10−14

Σ

0

(1940)

0.22 3.012×10−12

9.029×10−14

Σ

−

(1940)

0.22 3.012×10−12

9.029×10−14

K∗

(1410)

0.232 2.856×10−12

8.562×10−14

K∗+

(1410)

0.232 2.856×10−12

8.562×10−14

f4

(2050)

0.237 2.796×10−12

8.382×10−14

π+

1

(1600)

0.24 2.761×10−12

8.277×10−14

π0

1

(1600)

0.24 2.761×10−12

8.277×10−14

ρ+

(1700)

0.25

2.65×10−12

7.946×10−14

ρ0

(1700)

0.25

2.65×10−12

7.946×10−14

N

(1720)

0.25

2.65×10−12

7.946×10−14

N+

(1720)

0.25

2.65×10−12

7.946×10−14

a+

4

(2040)

0.257 2.578×10−12

7.729×10−14

Table A.1: Width (Γ), and mean proper lifetime (τ) of various particles,

sorted by descending lifetime

The ALICE definition of primary particles

15

Width Γ

Mean proper lifetime τ

Specie

(GeV)

(ps)

(cm/c)

a4

(2040)

0.257 2.578×10−12

7.729×10−14

π+

2

(1670)

0.26 2.548×10−12

7.64×10−14

∆

0

(1920)

0.26 2.548×10−12

7.64×10−14

∆

−

(1920)

0.26 2.548×10−12

7.64×10−14

π0

2

(1670)

0.26 2.548×10−12

7.64×10−14

∆

++

(1920)

0.26 2.548×10−12

7.64×10−14

∆

+

(1920)

0.26 2.548×10−12

7.64×10−14

a0

(1450)

0.265

2.5×10−12

7.496×10−14

a+

0

(1450)

0.265

2.5×10−12

7.496×10−14

D∗

0

(2400)

0.27 2.454×10−12

7.357×10−14

K∗

0

(1430)

0.27 2.454×10−12

7.357×10−14

K

∗+

0

(1430)

0.27 2.454×10−12

7.357×10−14

D

∗+

0

(2400)

0.27 2.454×10−12

7.357×10−14

K+

2

(1820)

0.276 2.401×10−12

7.197×10−14

K0

2

(1820)

0.276 2.401×10−12

7.197×10−14

∆

+

(1950)

0.28 2.366×10−12

7.094×10−14

∆

++

(1950)

0.28 2.366×10−12

7.094×10−14

∆

−

(1910)

0.28 2.366×10−12

7.094×10−14

∆

0

(1950)

0.28 2.366×10−12

7.094×10−14

∆

++

(1910)

0.28 2.366×10−12

7.094×10−14

∆

+

(1910)

0.28 2.366×10−12

7.094×10−14

∆

−

(1950)

0.28 2.366×10−12

7.094×10−14

∆

0

(1910)

0.28 2.366×10−12

7.094×10−14

∆

++

(1700)

0.3 2.209×10−12

6.621×10−14

∆

+

(1700)

0.3 2.209×10−12

6.621×10−14

∆

0

(1700)

0.3 2.209×10−12

6.621×10−14

∆

−

(1700)

0.3 2.209×10−12

6.621×10−14

Λ

(1800)

0.3 2.209×10−12

6.621×10−14

ω

(1650)

0.315 2.104×10−12

6.306×10−14

∆

+

(1600)

0.32 2.071×10−12

6.208×10−14

K∗

(1680)

0.32 2.071×10−12

6.208×10−14

K∗+

(1680)

0.32 2.071×10−12

6.208×10−14

f2

(2340)

0.32 2.071×10−12

6.208×10−14

∆

++

(1600)

0.32 2.071×10−12

6.208×10−14

∆

−

(1600)

0.32 2.071×10−12

6.208×10−14

∆

0

(1600)

0.32 2.071×10−12

6.208×10−14

∆

−

(1905)

0.33 2.008×10−12

6.02×10−14

π0

1

(1400)

0.33 2.008×10−12

6.02×10−14

π+

1

(1400)

0.33 2.008×10−12

6.02×10−14

∆

0

(1905)

0.33 2.008×10−12

6.02×10−14

∆

+

(1905)

0.33 2.008×10−12

6.02×10−14

∆

++

(1905)

0.33 2.008×10−12

6.02×10−14

f0

(1370)

0.35 1.893×10−12

5.676×10−14

N+

(1440)

0.35 1.893×10−12

5.676×10−14

N

(1440)

0.35 1.893×10−12

5.676×10−14

∆

++

(1930)

0.36 1.841×10−12

5.518×10−14

∆

+

(1930)

0.36 1.841×10−12

5.518×10−14

∆

0

(1930)

0.36 1.841×10−12

5.518×10−14

∆

−

(1930)

0.36 1.841×10−12

5.518×10−14

h1

(1170)

0.36 1.841×10−12

5.518×10−14

ρ+

(1450)

0.4 1.657×10−12

4.966×10−14

ρ0

(1450)

0.4 1.657×10−12

4.966×10−14

π+

(1300)

0.4 1.657×10−12

4.966×10−14

Table A.1: Width (Γ), and mean proper lifetime (τ) of various particles,

sorted by descending lifetime

16

ALICE Collaboration

Width Γ

Mean proper lifetime τ

Specie

(GeV)

(ps)

(cm/c)

π0

(1300)

0.4 1.657×10−12

4.966×10−14

a+

1

(1260)

0.42 1.578×10−12

4.73×10−14

a1

(1260)

0.42 1.578×10−12

4.73×10−14

f2

(1950)

0.472 1.404×10−12

4.209×10−14

N+

(2190)

0.5 1.325×10−12

3.973×10−14

N

(2190)

0.5 1.325×10−12

3.973×10−14

f0

(500)

0.55 1.205×10−12

3.612×10−14

t

1.41 4.699×10−13

1.409×10−14

H

1.7 3.898×10−13

1.168×10−14

W+

2.085 3.178×10−13

9.527×10−15

Z0

2.495 2.656×10−13

7.961×10−15

Table A.1: Width (Γ), and mean proper lifetime (τ) of various particles,

sorted by descending lifetime

B LATEX code of the definition

The definition given in Sect. 1 can be typeset in LATEX using the code below

A primary particle is a particle with a mean proper lifetime $\tau$

larger than $1\,\ mathrm{cm\kern -.03em/\kern -.05em c}$, which is

either a) produced directly in the interaction, or b) from decays of

particles with $\tau$ smaller than

$1\,\ mathrm{cm\kern -.03em/\kern -.05em c}$, restricted to decay

chains leading to the interaction.

The additional “kerning” used is to make the unit more compact and appear as a single entity. The

spacing macro \, can be avoid if the units package is used.

The ALICE definition of primary particles

17

C Rivet projection

The code below3 implements a Rivet [11] projection to project out primary particles according to the

definition.

#ifndef ALICEPRIMARY_CC

#define ALICEPRIMARY_CC

#include <Rivet/Particle.hh>

#include <Rivet/Event.hh>

#include <Rivet/Tools/ParticleIdUtils.hh>

#include <Rivet/Projections/ParticleFinder.hh>

#include <Rivet/ParticleName.hh>

#include <Rivet/Tools/Cuts.hh>

#include <HepMC/GenParticle.h>

#include <HepMC/GenVertex.h>

namespace Rivet

{

/**

* A Rivet projection that projects out primary particles - according

* to the ALICE definition - from an event.

The projection filters

* all charge states.

If one needs to have only charged particles

* one need to apply another projection on top of this one.

*

* This version is for Rivet version 2 and higher, which allows for

* the use of a Cut class and the base class ParticleFinder.

*/

class AlicePrimary : public ParticleFinder

{

public:

/**

* Consturctor

* @param cut If specified, use this cut when projecting

* @param pdg If specified, check for this PDG rather than long-lived

*/

AlicePrimary(const Cut& c=Cuts::open(),int pdg)

: ParticleFinder(c), _pdg(pdg)

{

setName("AlicePrimary");

}

/**

* Copy constructor

*

* @param o Object to copy from

*/

AlicePrimary(const AlicePrimary& o) : ParticleFinder(o),_pdg(o._pdg) {}

/**

* Destructor

*/

virtual ~AlicePrimary () {}

/**

* @{

* @name Projection interface

*/

/**

* Clone this projection object

*

* @return Copy of this projection object allocated on the heap

*/

3The code presented here is for Rivet version 2 or higher. For earlier version minor changes has to be done. Current

implementation can also be found at https://gitlab.cern.ch/cholm/alice-rivet.

18

ALICE Collaboration

virtual std::unique_ptr<Projection > clone() const

{

return std::unique_ptr<Projection >(new AlicePrimary (*this));

}

/**

* Compare this projection to some other projection.

If the other

* projection is also a AlicePrimary projection, then return @c 0,

* otherwise @c -1.

*

* @param p Projection to compare to

*

* @return 0 if @a p is an AlicePrimary, @c -1 otherwise

*/

virtual int compare(const Projection& p) const

{

const AlicePrimary* o = dynamic_cast <const AlicePrimary *>(&p);

if (!o || o->_pdg != _pdg) return UNDEFINED;

return _cuts == o->_cuts ? EQUIVALENT : UNDEFINED;

}

/**

* Project out the primary particles of the passed event record @a

* e.

This is the interface that does the actual projection.

*

* @param e Event record.

*/

virtual void project(const Event& e)

{

_theParticles.clear(); // Clear cache

bool open = _cuts == Cuts::open();

for (auto p : Rivet::particles(e.genEvent())) {

if (isPrimary(p,_pdg) && (open || _cuts->accept(Particle(p))))

_theParticles.push_back(Particle(*p));

}

}

/* @} */

/**

* @{

* @name Internal functions used

*/

/**

* Check if a particle is a primary according to the ALICE

* definition.

*

* @param p Particle to test

*

* @return true if the particle is considered a primary, false

* otherwise.

*/

static bool isPrimary(const HepMC:: GenParticle* p)

{

if

(_pdg != 0 && p->pdg_id() != pdg) return false;

else if (!isLongLived(p)) return false;

if (!(isPrompt(p) || isDecay(p))) return false;

const HepMC:: GenParticle* m = p;

while ((m = ancestor(m))) {

if (m->status() == 4) return true; // found beam

if (isLongLived(m)) return false;

if (!(isDecay(m) || isDecau(m))) return false;

}

return true;

}

The ALICE definition of primary particles

19

/**

* Check if a particle is of a long-lived (i.e., @f$ \tau>1cm@f$)

* species.

*

* @param p Particle to test

*

* @return true if the particle is of a long-lived species

*/

static bool isLongLived(const HepMC:: GenParticle* p)

{

int pdg = PID::abspid(p->pdg_id());

// Check for nuclus

if (pdg > 1000000000) return true;

switch (pdg) {

case Rivet::PID::MUON:

case Rivet::PID::ELECTRON:

case Rivet::PID::GAMMA:

case Rivet::PID::PIPLUS:

case Rivet::PID::KPLUS:

case Rivet::PID::K0S:

case Rivet::PID::K0L:

case Rivet::PID::PROTON:

case Rivet::PID::NEUTRON:

case Rivet::PID::LAMBDA:

case Rivet::PID::SIGMAMINUS:

case Rivet::PID::SIGMAPLUS:

case Rivet::PID::XIMINUS:

case Rivet::PID::XI0:

case Rivet::PID::OMEGAMINUS:

case Rivet::PID::NU_E:

case Rivet::PID::NU_MU:

case Rivet::PID::NU_TAU:

return true;

}

return false;

}

/**

* Check if this is prompt

*

* @param p Particle to test

*

* @return true if the particle has no ancestors, or from a

* quark or gluon. Some EGs (e.g., Pythia8) records the full

* event tree, so we check if this has indeed been hadronised.

*/

static bool isPrompt(const HepMC:: GenParticle* p)

{

// Get mother

const HepMC:: GenParticle* m = ancestor(p);

// If no mother, this is prompt

if (!m) return true;

// If mother is a quark or a gluon, consider daughter to be

// prompt, irrespective of the generation status code - Pythia8,

// for example, exports the full chain with "funny" status codes

int mpdg = PID::abspid(m->pdg_id());

switch (mpdg) {

case Rivet::PID::DQUARK:

case Rivet::PID::UQUARK:

case Rivet::PID::SQUARK:

case Rivet::PID::CQUARK:

case Rivet::PID::BQUARK:

20

ALICE Collaboration

case Rivet::PID::TQUARK:

case Rivet::PID::GLUON:

return true;

}

return m->status() == 4; // Check mother is beam

}

/**

* Check if a particle is either produced in a decay (@c

* status=2)

*

* @param p Particle to test

*

* @return true if either produced in the interaction or through

* some decay

*/

static bool isDecay(const HepMC:: GenParticle* p)

{

// Get mother

const HepMC:: GenParticle* m = ancestor(p);

// No mother, so prompt

if (!m) return true;

int mstatus = m->status();

// true if mother decayed or mother is beam particle

return mstatus == 2;

}

/**

* Get the immediate ancestor of a particle

*

* @param p The particle to get the ancestor for

*

* @return Ancestor particle or null

*/

static const HepMC:: GenParticle* ancestor(const HepMC:: GenParticle* p)

{

const HepMC:: GenVertex* vtx = p->production_vertex();

if (!vtx) return 0;

HepMC:: GenVertex ::particles_in_const_iterator i =

vtx->particles_in_const_begin();

if (i == vtx->particles_in_const_end()) return 0;

return *i;

}

/* @} */

};

}

#endif

//

// EOF

//

Note, the projection AlicePrimary and FinalState are generally not equivalent.

To use this projection in an analysis, one should do

#include <Rivet/Projections/AlicePrimary.hh>

#include <Rivet/Analysis.hh>

namespace Rivet

{

class AliceAnalysis : public Analysis

{

public:

AliceAnalysis () {}

The ALICE definition of primary particles

21

void init()

{

const AlicePrimary ap;

addProjection(ap, "AP");

}

void analyse(const Event& event)

{

const AlicePrimary& ap = applyProjection<AlicePrimary >(event,"AP");

// Loop over primaries - optionally pass a cut object to

// AlicePrimary::particles

for (auto p : ap.particles()) {

// Process particle p of type Rivet::Particle&

}

}

};

DECLARE_RIVET_PLUGIN(AliceAnalysis );

}

D Code

The code below checks if a particle is considered long-lived, i.e., has a proper lifetime τ > 1cm/c. If so,

it returns true, otherwise false.

Bool_t IsStable(const TParticle* p, Bool_t def=false) const

{

if (!p) return def;

Int_t pdg = TMath::Abs(p->GetPdgCode());

// Check for nuclus

if (pdg > 1000000000) return true;

Int_t stable[] = {

kGamma ,

// 22

Photon

kElectron ,

// 11

Electron

kMuonMinus ,

// 13

Muon

kPiPlus ,

// 211

Pion

kKPlus ,

// 321

Kaon

kK0Short ,

// 310

K0s

kK0Long ,

// 130

K0l

kProton ,

// 2212 Proton

kNeutron ,

// 2112 Neutron

kLambda0 ,

// 3122 Lambda_0

kSigmaMinus ,

// 3112 Sigma Minus

kSigmaPlus ,

// 3222 Sigma Plus

kXiMinus ,

// 3312 Xi Minus

3322,

//

Xi 0

kOmegaMinus ,

// 3334 Omega

kNuE ,

// 12

Electron Neutrino

kNuMu ,

// 14

Muon Neutrino

kNuTau ,

// 16

Tau Neutrino

-1

};

Int_t* ptr = stable;

while ((*ptr) >= 0) {

if (pdg == *ptr) return true;

ptr++;

}

return false;

}

22

ALICE Collaboration

The following code checks if the particle production mechanism either corresponds to production in the

interaction or a decay. The ALICE simulation framework stores the production identifier in the field

accessed by GetUniqueID() of the TParticle objects.

Bool_t IsPrimaryProcess(TParticle* p) const

{

switch (p->GetUniqueID()) {

case kPDecay:

case kPNoProcess:

case kPNull:

case kPPrimary:

return true;

}

return false;

}

Finally, we have the code that checks if a given particle is a primary. The argument of type AliStack

gives access to the full particle history of an event in the ALICE simulation framework.

Bool_t IsFirstStable(AliStack* stack, Int_t iTr)

{

TParticle* p = stack->Particle(iTr);

// Check if this particle is stable

if (!IsStable(p)) return false;

if (!IsPrimaryProcess(p)) return false;

TParticle* m

= p;

Int_t

mi = 0;

while ((mi = m->GetFirstMother()) >= 0) {

m = stack->Particle(mi);

// If there’s no mother, break out

if (!m) break;

// If (grand)mother particle is stable, this is not primary

if (IsStable(m)) return false;

// If (grand)mother was produced neither in a decay nor directly

// in the interaction (e.g., material interaction), then this

// particle is not a primary.

if (!IsPrimaryProcess(m)) return false;

}

// If we get here, then no (grand)mother was long-lived, and was

// either produced in a decay or directly in the interaction

return true;

}

To facilitate faster look-up, one may code up the above flagging particles as we search through the decay

chains

TParticle

MarkPrimary(TParticle* p, Bool_t primary)

{

p->SetBit(kPrimarySet);

if (primary) p->SetBit(kPrimaryBit);

else

p->ClearBit(kPrimaryBit);

return p;

}

Bool_t IsFirstStable(AliStack* stack, Int_t iTr)

{

TParticle* p = stack->Particle(iTr);

if (p->Testbit(kPrimarySet)) return p->TestBit(kPrimaryBit);

// Check if this particle is stable

if (!IsStable(p) || !IsPrimaryProcess(p)) {

MarkPrimary(p, false);

return false;

The ALICE definition of primary particles

23

}

TParticle* m

= p;

Int_t

mi = 0;

while ((mi = m->GetFirstMother()) >= 0) {

m = stack->Particle(mi);

// If there’s no mother, break out

if (!m) break;

// If (grand)mother was flagged as primary, then this is not

if ((m->Testbit(kPrimarySet) &&

m->TestBit(kPrimaryBit))) {

MarkPrimary(p, false);

return false;

}

// If (grand)mother is long-lived or her production mechanism is

// neither a decay nor the primary interaction (e.g., scattering

// in material), then this particle is not primary

if (IsStable(m) || !IsPrimaryProcess(m)) {

MarkPrimary(p, false);

return false;

}

// (Grand)mother is not a primary, mark it as such

MarkPrimary(m,false);

}

// If we get here, then all (grand)mothers was neither long-lived,

// nor produced in by any means but decays or in the primary

// interaction. Thus, we have a primary particle

MarkPrimary(m,true);

return true;

}

In this way, we do not need to fully traverse most of the decay chains.

E ALICE Collaboration

S. Acharya139, D. Adamová96, J. Adolfsson34, M.M. Aggarwal101, G. Aglieri Rinella35, M. Agnello31,

N. Agrawal48, Z. Ahammed139, N. Ahmad17, S.U. Ahn80, S. Aiola143, A. Akindinov65, S.N. Alam139,

J.L.B. Alba114, D.S.D. Albuquerque125, D. Aleksandrov92, B. Alessandro59, R. Alfaro Molina75, A. Alici12,27,54,

A. Alkin3, J. Alme22, T. Alt71, L. Altenkamper22, I. Altsybeev138, C. Alves Garcia Prado124, C. Andrei89,

D. Andreou35, H.A. Andrews113, A. Andronic109, V. Anguelov106, C. Anson99, T. Anticic110, F. Antinori57,

P. Antonioli54, R. Anwar127, L. Aphecetche117, H. Appelshäuser71, S. Arcelli27, R. Arnaldi59, O.W. Arnold36,107,

I.C. Arsene21, M. Arslandok106, B. Audurier117, A. Augustinus35, R. Averbeck109, M.D. Azmi17, A. Badal`a56,

Y.W. Baek61,79, S. Bagnasco59, R. Bailhache71, R. Bala103, A. Baldisseri76, M. Ball45, R.C. Baral68,

A.M. Barbano26, R. Barbera28, F. Barile33,53, L. Barioglio26, G.G. Barnaföldi142, L.S. Barnby95, V. Barret82,

P. Bartalini7, K. Barth35, E. Bartsch71, M. Basile27, N. Bastid82, S. Basu141, B. Bathen72, G. Batigne117,

B. Batyunya78, P.C. Batzing21, I.G. Bearden93, H. Beck106, C. Bedda64, N.K. Behera61, I. Belikov135,

F. Bellini27, H. Bello Martinez2, R. Bellwied127, L.G.E. Beltran123, V. Belyaev85, G. Bencedi142, S. Beole26,

A. Bercuci89, Y. Berdnikov98, D. Berenyi142, R.A. Bertens130, D. Berzano35, L. Betev35, A. Bhasin103,

I.R. Bhat103, A.K. Bhati101, B. Bhattacharjee44, J. Bhom121, L. Bianchi127, N. Bianchi51, C. Bianchin141,

J. Bielcık39, J. Bielcıková96, A. Bilandzic36,107, G. Biro142, R. Biswas4, S. Biswas4, J.T. Blair122, D. Blau92,

C. Blume71, G. Boca136, F. Bock35,84,106, A. Bogdanov85, L. Boldizsár142, M. Bombara40, G. Bonomi137,

M. Bonora35, J. Book71, H. Borel76, A. Borissov19, M. Borri129, E. Botta26, C. Bourjau93, L. Bratrud71,

P. Braun-Munzinger109, M. Bregant124, T.A. Broker71, M. Broz39, E.J. Brucken46, E. Bruna59, G.E. Bruno33,

D. Budnikov111, H. Buesching71, S. Bufalino31, P. Buhler116, P. Buncic35, O. Busch133, Z. Buthelezi77,

J.B. Butt15, J.T. Buxton18, J. Cabala119, D. Caffarri35,94, H. Caines143, A. Caliva64, E. Calvo Villar114,

P. Camerini25, A.A. Capon116, F. Carena35, W. Carena35, F. Carnesecchi12,27, J. Castillo Castellanos76,

24

ALICE Collaboration

A.J. Castro130, E.A.R. Casula55, C. Ceballos Sanchez9, P. Cerello59, S. Chandra139, B. Chang128, S. Chapeland35,

M. Chartier129, J.L. Charvet76, S. Chattopadhyay139, S. Chattopadhyay112, A. Chauvin36,107, M. Cherney99,

C. Cheshkov134, B. Cheynis134, V. Chibante Barroso35, D.D. Chinellato125, S. Cho61, P. Chochula35,

K. Choi19, M. Chojnacki93, S. Choudhury139, T. Chowdhury82, P. Christakoglou94, C.H. Christensen93,

P. Christiansen34, T. Chujo133, S.U. Chung19, C. Cicalo55, L. Cifarelli12,27, F. Cindolo54, J. Cleymans102,

F. Colamaria33, D. Colella35,66, A. Collu84, M. Colocci27, M. ConcasII,59, G. Conesa Balbastre83, Z. Conesa

del Valle62, M.E. ConnorsIII,143, J.G. Contreras39, T.M. Cormier97, Y. Corrales Morales59, I. Cortés

Maldonado2, P. Cortese32, M.R. Cosentino126, F. Costa35, S. Costanza136, J. Crkovská62, P. Crochet82,

E. Cuautle73, L. Cunqueiro72, T. Dahms36,107, A. Dainese57, M.C. Danisch106, A. Danu69, D. Das112,

I. Das112, S. Das4, A. Dash90, S. Dash48, S. De49,124, A. De Caro30, G. de Cataldo53, C. de Conti124, J. de

Cuveland42, A. De Falco24, D. De Gruttola12,30, N. De Marco59, S. De Pasquale30, R.D. De Souza125,

H.F. Degenhardt124, A. Deisting106,109, A. Deloff88, C. Deplano94, P. Dhankher48, D. Di Bari33, A. Di

Mauro35, P. Di Nezza51, B. Di Ruzza57, M.A. Diaz Corchero10, T. Dietel102, P. Dillenseger71, R. Divi`a35,

Ø. Djuvsland22, A. Dobrin35, D. Domenicis Gimenez124, B. Dönigus71, O. Dordic21, L.V.V. Doremalen64,

A.K. Dubey139, A. Dubla109, L. Ducroux134, A.K. Duggal101, P. Dupieux82, R.J. Ehlers143, D. Elia53,

E. Endress114, H. Engel70, E. Epple143, B. Erazmus117, F. Erhardt100, B. Espagnon62, S. Esumi133,

G. Eulisse35, J. Eum19, D. Evans113, S. Evdokimov115, L. Fabbietti36,107, J. Faivre83, A. Fantoni51,

M. Fasel84,97, L. Feldkamp72, A. Feliciello59, G. Feofilov138, J. Ferencei96, A. Fernández Téllez2, E.G. Ferreiro16,

A. Ferretti26, A. Festanti29,35, V.J.G. Feuillard76,82, J. Figiel121, M.A.S. Figueredo124, S. Filchagin111,

D. Finogeev63, F.M. Fionda22,24, E.M. Fiore33, M. Floris35, S. Foertsch77, P. Foka109, S. Fokin92, E. Fragiacomo60,

A. Francescon35, A. Francisco117, U. Frankenfeld109, G.G. Fronze26, U. Fuchs35, C. Furget83, A. Furs63,

M. Fusco Girard30, J.J. Gaardhøje93, M. Gagliardi26, A.M. Gago114, K. Gajdosova93, M. Gallio26,

C.D. Galvan123, P. Ganoti87, C. Gao7, C. Garabatos109, E. Garcia-Solis13, K. Garg28, C. Gargiulo35,

P. Gasik36,107, E.F. Gauger122, M.B. Gay Ducati74, M. Germain117, J. Ghosh112, P. Ghosh139, S.K. Ghosh4,

P. Gianotti51, P. Giubellino35,59,109, P. Giubilato29, E. Gladysz-Dziadus121, P. Glässel106, D.M. Goméz

Coral75, A. Gomez Ramirez70, A.S. Gonzalez35, V. Gonzalez10, P. González-Zamora10, S. Gorbunov42,

L. G örlich121, S. Gotovac120, V. Grabski75, L.K. Graczykowski140, K.L. Graham113, L. Greiner84, A. Grelli64,

C. Grigoras35, V. Grigoriev85, A. Grigoryan1, S. Grigoryan78, N. Grion60, J.M. Gronefeld109, F. Grosa31,

J.F. Grosse-Oetringhaus35, R. Grosso109, L. Gruber116, F. Guber63, R. Guernane83, B. Guerzoni27, K. Gulbrandsen93,

T. Gunji132, A. Gupta103, R. Gupta103, I.B. Guzman2, R. Haake35, C. Hadjidakis62, H. Hamagaki86,132,

G. Hamar142, J.C. Hamon135, M.R. Haque64, J.W. Harris143, A. Harton13, H. Hassan83, D. Hatzifotiadou12,54,

S. Hayashi132, S.T. Heckel71, E. Hellbär71, H. Helstrup37, A. Herghelegiu89, G. Herrera Corral11, F. Herrmann72,

B.A. Hess105, K.F. Hetland37, H. Hillemanns35, C. Hills129, B. Hippolyte135, J. Hladky67, B. Hohlweger107,

D. Horak39, S. Hornung109, R. Hosokawa83,133, P. Hristov35, C. Hughes130, T.J. Humanic18, N. Hussain44,

T. Hussain17, D. Hutter42, D.S. Hwang20, S.A. Iga Buitron73, R. Ilkaev111, M. Inaba133, M. Ippolitov85,92,

M. Irfan17, V. Isakov63, M. Ivanov109, V. Ivanov98, V. Izucheev115, B. Jacak84, N. Jacazio27, P.M. Jacobs84,

M.B. Jadhav48, J. Jadlovsky119, S. Jaelani64, C. Jahnke36, M.J. Jakubowska140, M.A. Janik140, P.H.S.Y. Jayarathna127,

C. Jena90, S. Jena127, M. Jercic100, R.T. Jimenez Bustamante109, P.G. Jones113, A. Jusko113, P. Kalinak66,

A. Kalweit35, J.H. Kang144, V. Kaplin85, S. Kar139, A. Karasu Uysal81, O. Karavichev63, T. Karavicheva63,

L. Karayan106,109, P. Karczmarczyk35, E. Karpechev63, U. Kebschull70, R. Keidel145, D.L.D. Keijdener64,

M. Keil35, B. Ketzer45, Z. Khabanova94, P. Khan112, S.A. Khan139, A. Khanzadeev98, Y. Kharlov115,

A. Khatun17, A. Khuntia49, M.M. Kielbowicz121, B. Kileng37, B. Kim133, D. Kim144, D.W. Kim43,

D.J. Kim128, H. Kim144, J.S. Kim43, J. Kim106, M. Kim61, M. Kim144, S. Kim20, T. Kim144, S. Kirsch42,

I. Kisel42, S. Kiselev65, A. Kisiel140, G. Kiss142, J.L. Klay6, C. Klein71, J. Klein35, C. Klein-Bösing72,

S. Klewin106, A. Kluge35, M.L. Knichel106, A.G. Knospe127, C. Kobdaj118, M. Kofarago142, T. Kollegger109,

A. Kolojvari138, V. Kondratiev138, N. Kondratyeva85, E. Kondratyuk115, A. Konevskikh63, M. Konyushikhin141,

M. Kopcik119, M. Kour103, C. Kouzinopoulos35, O. Kovalenko88, V. Kovalenko138, M. Kowalski121,

G. Koyithatta Meethaleveedu48, I. Králik66, A. Kravcáková40, M. Krivda66,113, F. Krizek96, E. Kryshen98,

M. Krzewicki42, A.M. Kubera18, V. Kucera96, C. Kuhn135, P.G. Kuijer94, A. Kumar103, J. Kumar48,

L. Kumar101, S. Kumar48, S. Kundu90, P. Kurashvili88, A. Kurepin63, A.B. Kurepin63, A. Kuryakin111,

The ALICE definition of primary particles

25

S. Kushpil96, M.J. Kweon61, Y. Kwon144, S.L. La Pointe42, P. La Rocca28, C. Lagana Fernandes124,

Y.S. Lai84, I. Lakomov35, R. Langoy41, K. Lapidus143, C. Lara70, A. Lardeux21,76, A. Lattuca26, E. Laudi35,

R. Lavicka39, L. Lazaridis35, R. Lea25, L. Leardini106, S. Lee144, F. Lehas94, S. Lehner116, J. Lehrbach42,

R.C. Lemmon95, V. Lenti53, E. Leogrande64, I. León Monzón123, P. Lévai142, S. Li7, X. Li14, J. Lien41,

R. Lietava113, B. Lim19, S. Lindal21, V. Lindenstruth42, S.W. Lindsay129, C. Lippmann109, M.A. Lisa18,

V. Litichevskyi46, H.M. Ljunggren34, W.J. Llope141, D.F. Lodato64, P.I. Loenne22, V. Loginov85, C. Loizides84,

P. Loncar120, X. Lopez82, E. López Torres9, A. Lowe142, P. Luettig71, M. Lunardon29, G. Luparello25,60,

M. Lupi35, T.H. Lutz143, A. Maevskaya63, M. Mager35, S. Mahajan103, S.M. Mahmood21, A. Maire135,

R.D. Majka143, M. Malaev98, L. MalininaIV,78, D. Mal’Kevich65, P. Malzacher109, A. Mamonov111,

V. Manko92, F. Manso82, V. Manzari53, Y. Mao7, M. Marchisone77,131, J. Mareš67, G.V. Margagliotti25,

A. Margotti54, J. Margutti64, A. Marın109, C. Markert122, M. Marquard71, N.A. Martin109, P. Martinengo35,

J.A.L. Martinez70, M.I. Martınez2, G. Martınez Garcıa117, M. Martinez Pedreira35, A. Mas124, S. Masciocchi109,

M. Masera26, A. Masoni55, E. Masson117, A. Mastroserio53, A.M. Mathis36,107, A. Matyja121,130, C. Mayer121,

J. Mazer130, M. Mazzilli33, M.A. Mazzoni58, F. Meddi23, Y. Melikyan85, A. Menchaca-Rocha75, E. Meninno30,

J. Mercado Pérez106, M. Meres38, S. Mhlanga102, Y. Miake133, M.M. Mieskolainen46, D. Mihaylov107,

D.L. Mihaylov107, K. Mikhaylov65,78, L. Milano84, J. Milosevic21, A. Mischke64, A.N. Mishra49, D. Miskowiec109,

J. Mitra139, C.M. Mitu69, N. Mohammadi64, B. Mohanty90, M. Mohisin KhanV,17, E. Montes10, D.A. Mor-

eira De Godoy72, L.A.P. Moreno2, S. Moretto29, A. Morreale117, A. Morsch35, V. Muccifora51, E. Mudnic120,

D. Mühlheim72, S. Muhuri139, M. Mukherjee4, J.D. Mulligan143, M.G. Munhoz124, K. Münning45,

R.H. Munzer71, H. Murakami132, S. Murray77, L. Musa35, J. Musinsky66, C.J. Myers127, J.W. Myrcha140,

B. Naik48, R. Nair88, B.K. Nandi48, R. Nania12,54, E. Nappi53, A. Narayan48, M.U. Naru15, H. Na-

tal da Luz124, C. Nattrass130, S.R. Navarro2, K. Nayak90, R. Nayak48, T.K. Nayak139, S. Nazarenko111,

A. Nedosekin65, R.A. Negrao De Oliveira35, L. Nellen73, S.V. Nesbo37, F. Ng127, M. Nicassio109, M. Niculescu69,

J. Niedziela35,140, B.S. Nielsen93, S. Nikolaev92, S. Nikulin92, V. Nikulin98, A. Nobuhiro47, F. Noferini12,54,

P. Nomokonov78, G. Nooren64, J.C.C. Noris2, J. Norman129, A. Nyanin92, J. Nystrand22, H. OeschlerI,106,

S. Oh143, A. Ohlson35,106, T. Okubo47, L. Olah142, J. Oleniacz140, A.C. Oliveira Da Silva124, M.H. Oliver143,

J. Onderwaater109, C. Oppedisano59, R. Orava46, M. Oravec119, A. Ortiz Velasquez73, A. Oskarsson34,

J. Otwinowski121, K. Oyama86, Y. Pachmayer106, V. Pacik93, D. Pagano137, P. Pagano30, G. Paic73,

P. Palni7, J. Pan141, A.K. Pandey48, S. Panebianco76, V. Papikyan1, G.S. Pappalardo56, P. Pareek49,

J. Park61, S. Parmar101, A. Passfeld72, S.P. Pathak127, V. Paticchio53, R.N. Patra139, B. Paul59, H. Pei7,

T. Peitzmann64, X. Peng7, L.G. Pereira74, H. Pereira Da Costa76, D. Peresunko85,92, E. Perez Lezama71,

V. Peskov71, Y. Pestov5, V. Petrácek39, V. Petrov115, M. Petrovici89, C. Petta28, R.P. Pezzi74, S. Piano60,

M. Pikna38, P. Pillot117, L.O.D.L. Pimentel93, O. Pinazza35,54, L. Pinsky127, D.B. Piyarathna127, M. Płoskon84,

M. Planinic100, F. Pliquett71, J. Pluta140, S. Pochybova142, P.L.M. Podesta-Lerma123, M.G. Poghosyan97,

B. Polichtchouk115, N. Poljak100, W. Poonsawat118, A. Pop89, H. Poppenborg72, S. Porteboeuf-Houssais82,

J. Porter84, V. Pozdniakov78, S.K. Prasad4, R. Preghenella54, F. Prino59, C.A. Pruneau141, I. Pshenichnov63,

M. Puccio26, G. Puddu24, P. Pujahari141, V. Punin111, J. Putschke141, A. Rachevski60, S. Raha4, S. Rajput103,

J. Rak128, A. Rakotozafindrabe76, L. Ramello32, F. Rami135, D.B. Rana127, R. Raniwala104, S. Raniwala104,

S.S. Räsänen46, B.T. Rascanu71, D. Rathee101, V. Ratza45, I. Ravasenga31, K.F. Read97,130, K. RedlichVI,88,

A. Rehman22, P. Reichelt71, F. Reidt35, X. Ren7, R. Renfordt71, A.R. Reolon51, A. Reshetin63, K. Reygers106,

V. Riabov98, R.A. Ricci52, T. Richert64, M. Richter21, P. Riedler35, W. Riegler35, F. Riggi28, C. Ristea69,

M. Rodrıguez Cahuantzi2, K. Røed21, E. Rogochaya78, D. Rohr35,42, D. Röhrich22, P.S. Rokita140,

F. Ronchetti51, E.D. Rosas73, P. Rosnet82, A. Rossi29,57, A. Rotondi136, F. Roukoutakis87, A. Roy49,

C. Roy135, P. Roy112, A.J. Rubio Montero10, O.V. Rueda73, R. Rui25, B. Rumyantsev78, A. Rustamov91,

E. Ryabinkin92, Y. Ryabov98, A. Rybicki121, S. Saarinen46, S. Sadhu139, S. Sadovsky115, K. Šafarık35,

S.K. Saha139, B. Sahlmuller71, B. Sahoo48, P. Sahoo49, R. Sahoo49, S. Sahoo68, P.K. Sahu68, J. Saini139,

S. Sakai51,133, M.A. Saleh141, J. Salzwedel18, S. Sambyal103, V. Samsonov85,98, A. Sandoval75, D. Sarkar139,

N. Sarkar139, P. Sarma44, M.H.P. Sas64, E. Scapparone54, F. Scarlassara29, R.P. Scharenberg108, H.S. Scheid71,

C. Schiaua89, R. Schicker106, C. Schmidt109, H.R. Schmidt105, M.O. Schmidt106, M. Schmidt105, N.V. Schmidt71,

S. Schuchmann106, J. Schukraft35, Y. Schutz35,117,135, K. Schwarz109, K. Schweda109, G. Scioli27, E. Scomparin59,

26

ALICE Collaboration

R. Scott130, M. Šefcık40, J.E. Seger99, Y. Sekiguchi132, D. Sekihata47, I. Selyuzhenkov85,109, K. Senosi77,

S. Senyukov3,35,135, E. Serradilla10,75, P. Sett48, A. Sevcenco69, A. Shabanov63, A. Shabetai117, R. Shahoyan35,

W. Shaikh112, A. Shangaraev115, A. Sharma101, A. Sharma103, M. Sharma103, M. Sharma103, N. Sharma101,130,

A.I. Sheikh139, K. Shigaki47, Q. Shou7, K. Shtejer9,26, Y. Sibiriak92, S. Siddhanta55, K.M. Sielewicz35,

T. Siemiarczuk88, D. Silvermyr34, C. Silvestre83, G. Simatovic100, G. Simonetti35, R. Singaraju139,

R. Singh90, V. Singhal139, T. Sinha112, B. Sitar38, M. Sitta32, T.B. Skaali21, M. Slupecki128, N. Smirnov143,

R.J.M. Snellings64, T.W. Snellman128, J. Song19, M. Song144, F. Soramel29, S. Sorensen130, F. Sozzi109,

E. Spiriti51, I. Sputowska121, B.K. Srivastava108, J. Stachel106, I. Stan69, P. Stankus97, E. Stenlund34,

D. Stocco117, M.M. Storetvedt37, P. Strmen38, A.A.P. Suaide124, T. Sugitate47, C. Suire62, M. Suleymanov15,

M. Suljic25, R. Sultanov65, M. Šumbera96, S. Sumowidagdo50, K. Suzuki116, S. Swain68, A. Szabo38,

I. Szarka38, U. Tabassam15, J. Takahashi125, G.J. Tambave22, N. Tanaka133, M. Tarhini62, M. Tariq17,

M.G. Tarzila89, A. Tauro35, G. Tejeda Mu˜noz2, A. Telesca35, K. Terasaki132, C. Terrevoli29, B. Teyssier134,

D. Thakur49, S. Thakur139, D. Thomas122, F. Thoresen93, R. Tieulent134, A. Tikhonov63, A.R. Timmins127,

A. Toia71, S. Tripathy49, S. Trogolo26, G. Trombetta33, L. Tropp40, V. Trubnikov3, W.H. Trzaska128,

B.A. Trzeciak64, T. Tsuji132, A. Tumkin111, R. Turrisi57, T.S. Tveter21, K. Ullaland22, E.N. Umaka127,

A. Uras134, G.L. Usai24, A. Utrobicic100, M. Vala66,119, J. Van Der Maarel64, J.W. Van Hoorne35,

M. van Leeuwen64, T. Vanat96, P. Vande Vyvre35, D. Varga142, A. Vargas2, M. Vargyas128, R. Varma48,

M. Vasileiou87, A. Vasiliev92, A. Vauthier83, O. Vázquez Doce36,107, V. Vechernin138, A.M. Veen64,

A. Velure22, E. Vercellin26, S. Vergara Limón2, R. Vernet8, R. Vértesi142, L. Vickovic120, S. Vigolo64,

J. Viinikainen128, Z. Vilakazi131, O. Villalobos Baillie113, A. Villatoro Tello2, A. Vinogradov92, L. Vinogradov138,

T. Virgili30, V. Vislavicius34, A. Vodopyanov78, M.A. Völkl105,106, K. Voloshin65, S.A. Voloshin141,

G. Volpe33, B. von Haller35, I. Vorobyev36,107, D. Voscek119, D. Vranic35,109, J. Vrláková40, B. Wagner22,

H. Wang64, M. Wang7, D. Watanabe133, Y. Watanabe132, M. Weber116, S.G. Weber109, D.F. Weiser106,

S.C. Wenzel35, J.P. Wessels72, U. Westerhoff72, A.M. Whitehead102, J. Wiechula71, J. Wikne21, G. Wilk88,

J. Wilkinson54,106, G.A. Willems72, M.C.S. Williams54, E. Willsher113, B. Windelband106, W.E. Witt130,

S. Yalcin81, K. Yamakawa47, P. Yang7, S. Yano47, Z. Yin7, H. Yokoyama83,133, I.-K. Yoo19,35, J.H. Yoon61,

V. Yurchenko3, V. Zaccolo59,93, A. Zaman15, C. Zampolli35, H.J.C. Zanoli124, N. Zardoshti113, A. Zarochentsev138,

P. Závada67, N. Zaviyalov111, H. Zbroszczyk140, M. Zhalov98, H. Zhang7,22, X. Zhang7, Y. Zhang7,

C. Zhang64, Z. Zhang7,82, C. Zhao21, N. Zhigareva65, D. Zhou7, Y. Zhou93, Z. Zhou22, H. Zhu22, J. Zhu7,

X. Zhu7, A. Zichichi12,27, A. Zimmermann106, M.B. Zimmermann35,72, G. Zinovjev3, J. Zmeskal116,

S. Zou7

Affiliation Notes

I Deceased

II Also at: Dipartimento DET del Politecnico di Torino, Turin, Italy

III Also at: Georgia State University, Atlanta, Georgia, United States

IV Also at: M.V. Lomonosov Moscow State University, D.V. Skobeltsyn Institute of Nuclear, Physics,

Moscow, Russia

V Also at: Department of Applied Physics, Aligarh Muslim University, Aligarh, India

VI Also at: Institute of Theoretical Physics, University of Wroclaw, Poland

Collaboration Institutes

1 A.I. Alikhanyan National Science Laboratory (Yerevan Physics Institute) Foundation, Yerevan, Arme-

nia

The ALICE definition of primary particles

27

2 Benemérita Universidad Autónoma de Puebla, Puebla, Mexico

3 Bogolyubov Institute for Theoretical Physics, Kiev, Ukraine

4 Bose Institute, Department of Physics and Centre for Astroparticle Physics and Space Science (CAPSS),

Kolkata, India

5 Budker Institute for Nuclear Physics, Novosibirsk, Russia

6 California Polytechnic State University, San Luis Obispo, California, United States

7 Central China Normal University, Wuhan, China

8 Centre de Calcul de l’IN2P3, Villeurbanne, Lyon, France

9 Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear (CEADEN), Havana, Cuba

10 Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain

11 Centro de Investigación y de Estudios Avanzados (CINVESTAV), Mexico City and Mérida, Mexico

12 Centro Fermi - Museo Storico della Fisica e Centro Studi e Ricerche “Enrico Fermi’, Rome, Italy

13 Chicago State University, Chicago, Illinois, United States

14 China Institute of Atomic Energy, Beijing, China

15 COMSATS Institute of Information Technology (CIIT), Islamabad, Pakistan

16 Departamento de Fısica de Partıculas and IGFAE, Universidad de Santiago de Compostela, Santiago

de Compostela, Spain

17 Department of Physics, Aligarh Muslim University, Aligarh, India

18 Department of Physics, Ohio State University, Columbus, Ohio, United States

19 Department of Physics, Pusan National University, Pusan, Republic of Korea

20 Department of Physics, Sejong University, Seoul, Republic of Korea

21 Department of Physics, University of Oslo, Oslo, Norway

22 Department of Physics and Technology, University of Bergen, Bergen, Norway

23 Dipartimento di Fisica dell’Universit`a ’La Sapienza’ and Sezione INFN, Rome, Italy

24 Dipartimento di Fisica dell’Universit`a and Sezione INFN, Cagliari, Italy

25 Dipartimento di Fisica dell’Universit`a and Sezione INFN, Trieste, Italy

26 Dipartimento di Fisica dell’Universit`a and Sezione INFN, Turin, Italy

27 Dipartimento di Fisica e Astronomia dell’Universit`a and Sezione INFN, Bologna, Italy

28 Dipartimento di Fisica e Astronomia dell’Universit`a and Sezione INFN, Catania, Italy

29 Dipartimento di Fisica e Astronomia dell’Universit`a and Sezione INFN, Padova, Italy

30 Dipartimento di Fisica ‘E.R. Caianiello’ dell’Universit`a and Gruppo Collegato INFN, Salerno, Italy

31 Dipartimento DISAT del Politecnico and Sezione INFN, Turin, Italy

32 Dipartimento di Scienze e Innovazione Tecnologica dell’Universit`a del Piemonte Orientale and INFN

Sezione di Torino, Alessandria, Italy

33 Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy

34 Division of Experimental High Energy Physics, University of Lund, Lund, Sweden

35 European Organization for Nuclear Research (CERN), Geneva, Switzerland

36 Excellence Cluster Universe, Technische Universität München, Munich, Germany

37 Faculty of Engineering, Bergen University College, Bergen, Norway

38 Faculty of Mathematics, Physics and Informatics, Comenius University, Bratislava, Slovakia

39 Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague,

Czech Republic

40 Faculty of Science, P.J. Šafárik University, Košice, Slovakia

41 Faculty of Technology, Buskerud and Vestfold University College, Tonsberg, Norway

42 Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt,

Germany

43 Gangneung-Wonju National University, Gangneung, Republic of Korea

44 Gauhati University, Department of Physics, Guwahati, India

45 Helmholtz-Institut für Strahlen- und Kernphysik, Rheinische Friedrich-Wilhelms-Universität Bonn,

Bonn, Germany

28

ALICE Collaboration

46 Helsinki Institute of Physics (HIP), Helsinki, Finland

47 Hiroshima University, Hiroshima, Japan

48 Indian Institute of Technology Bombay (IIT), Mumbai, India

49 Indian Institute of Technology Indore, Indore, India

50 Indonesian Institute of Sciences, Jakarta, Indonesia

51 INFN, Laboratori Nazionali di Frascati, Frascati, Italy

52 INFN, Laboratori Nazionali di Legnaro, Legnaro, Italy

53 INFN, Sezione di Bari, Bari, Italy

54 INFN, Sezione di Bologna, Bologna, Italy

55 INFN, Sezione di Cagliari, Cagliari, Italy

56 INFN, Sezione di Catania, Catania, Italy

57 INFN, Sezione di Padova, Padova, Italy

58 INFN, Sezione di Roma, Rome, Italy

59 INFN, Sezione di Torino, Turin, Italy

60 INFN, Sezione di Trieste, Trieste, Italy

61 Inha University, Incheon, Republic of Korea

62 Institut de Physique Nucléaire d’Orsay (IPNO), Université Paris-Sud, CNRS-IN2P3, Orsay, France

63 Institute for Nuclear Research, Academy of Sciences, Moscow, Russia

64 Institute for Subatomic Physics of Utrecht University, Utrecht, Netherlands

65 Institute for Theoretical and Experimental Physics, Moscow, Russia

66 Institute of Experimental Physics, Slovak Academy of Sciences, Košice, Slovakia

67 Institute of Physics, Academy of Sciences of the Czech Republic, Prague, Czech Republic

68 Institute of Physics, Bhubaneswar, India

69 Institute of Space Science (ISS), Bucharest, Romania

70 Institut für Informatik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany

71 Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany

72 Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Münster, Germany

73 Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Mexico City, Mexico

74 Instituto de Fısica, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil

75 Instituto de Fısica, Universidad Nacional Autónoma de México, Mexico City, Mexico

76 IRFU, CEA, Université Paris-Saclay, Saclay, France

77 iThemba LABS, National Research Foundation, Somerset West, South Africa

78 Joint Institute for Nuclear Research (JINR), Dubna, Russia

79 Konkuk University, Seoul, Republic of Korea

80 Korea Institute of Science and Technology Information, Daejeon, Republic of Korea

81 KTO Karatay University, Konya, Turkey

82 Laboratoire de Physique Corpusculaire (LPC), Clermont Université, Université Blaise Pascal, CNRS–

IN2P3, Clermont-Ferrand, France

83 Laboratoire de Physique Subatomique et de Cosmologie, Université Grenoble-Alpes, CNRS-IN2P3,

Grenoble, France

84 Lawrence Berkeley National Laboratory, Berkeley, California, United States

85 Moscow Engineering Physics Institute, Moscow, Russia

86 Nagasaki Institute of Applied Science, Nagasaki, Japan

87 National and Kapodistrian University of Athens, Physics Department, Athens, Greece

88 National Centre for Nuclear Studies, Warsaw, Poland

89 National Institute for Physics and Nuclear Engineering, Bucharest, Romania

90 National Institute of Science Education and Research, HBNI, Jatni, India

91 National Nuclear Research Center, Baku, Azerbaijan

92 National Research Centre Kurchatov Institute, Moscow, Russia

93 Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark

The ALICE definition of primary particles

29

94 Nikhef, Nationaal instituut voor subatomaire fysica, Amsterdam, Netherlands

95 Nuclear Physics Group, STFC Daresbury Laboratory, Daresbury, United Kingdom

96 Nuclear Physics Institute, Academy of Sciences of the Czech Republic, ˇRez u Prahy, Czech Republic

97 Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States

98 Petersburg Nuclear Physics Institute, Gatchina, Russia

99 Physics Department, Creighton University, Omaha, Nebraska, United States

100 Physics department, Faculty of science, University of Zagreb, Zagreb, Croatia

101 Physics Department, Panjab University, Chandigarh, India

102 Physics Department, University of Cape Town, Cape Town, South Africa

103 Physics Department, University of Jammu, Jammu, India

104 Physics Department, University of Rajasthan, Jaipur, India

105 Physikalisches Institut, Eberhard Karls Universität Tübingen, Tübingen, Germany

106 Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany

107 Physik Department, Technische Universität München, Munich, Germany

108 Purdue University, West Lafayette, Indiana, United States

109 Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionen-

forschung GmbH, Darmstadt, Germany

110 Rudjer Boškovic Institute, Zagreb, Croatia

111 Russian Federal Nuclear Center (VNIIEF), Sarov, Russia

112 Saha Institute of Nuclear Physics, Kolkata, India

113 School of Physics and Astronomy, University of Birmingham, Birmingham, United Kingdom

114 Sección Fısica, Departamento de Ciencias, Pontificia Universidad Católica del Perú, Lima, Peru

115 SSC IHEP of NRC Kurchatov institute, Protvino, Russia

116 Stefan Meyer Institut für Subatomare Physik (SMI), Vienna, Austria

117 SUBATECH, IMT Atlantique, Université de Nantes, CNRS-IN2P3, Nantes, France

118 Suranaree University of Technology, Nakhon Ratchasima, Thailand

119 Technical University of Košice, Košice, Slovakia

120 Technical University of Split FESB, Split, Croatia

121 The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Cracow,

Poland

122 The University of Texas at Austin, Physics Department, Austin, Texas, United States

123 Universidad Autónoma de Sinaloa, Culiacán, Mexico

124 Universidade de S˜ao Paulo (USP), S˜ao Paulo, Brazil

125 Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil

126 Universidade Federal do ABC, Santo Andre, Brazil

127 University of Houston, Houston, Texas, United States

128 University of Jyväskylä, Jyväskylä, Finland

129 University of Liverpool, Liverpool, United Kingdom

130 University of Tennessee, Knoxville, Tennessee, United States

131 University of the Witwatersrand, Johannesburg, South Africa

132 University of Tokyo, Tokyo, Japan

133 University of Tsukuba, Tsukuba, Japan

134 Université de Lyon, Université Lyon 1, CNRS/IN2P3, IPN-Lyon, Villeurbanne, Lyon, France

135 Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg, France, Strasbourg, France

136 Universit`a degli Studi di Pavia and Sezione INFN, Pavia, Italy

137 Universit`a di Brescia and Sezione INFN, Brescia, Italy

138 V. Fock Institute for Physics, St. Petersburg State University, St. Petersburg, Russia

139 Variable Energy Cyclotron Centre, Kolkata, India

140 Warsaw University of Technology, Warsaw, Poland

141 Wayne State University, Detroit, Michigan, United States

30

ALICE Collaboration

142 Wigner Research Centre for Physics, Hungarian Academy of Sciences, Budapest, Hungary

143 Yale University, New Haven, Connecticut, United States

144 Yonsei University, Seoul, Republic of Korea

145 Zentrum für Technologietransfer und Telekommunikation (ZTT), Fachhochschule Worms, Worms,

Germany