We investigate the influence of modified nuclear parton distribution functions (PDFs) on high-pT ... more We investigate the influence of modified nuclear parton distribution functions (PDFs) on high-pT hadron production at RHIC and LHC energies using a pQCD-improved parton model. For application at RHIC, we focus on the possible contribution of the EMC modification of the nuclear PDFs in the x > 0.3 region to the observed suppression of pi0 production at pT > 10
In this work we compare the nuclear modification factors in proton (deuteron) — nucleus collision... more In this work we compare the nuclear modification factors in proton (deuteron) — nucleus collisions at CERN SPS, FNAL and RHIC energies in a wide pT range. In these experiments the nuclear modification factor has shown an enhancement at pT ≈ 4 GeV /c. The height of this “Cronin peak” depends on the c.m. energy of the collision, as it is subject to stronger shadowing at higher energies. One of the aims of this contribution is to analyze the shadowing phenomenon at lower (2 GeV / c ≲ pT ≲ 4 GeV / c ) and intermediate (4 GeV / c ≲ pT ≲ 8 GeV / c ) transverse momentum. Different shadowing parametrizations are considered and the obtained Cronin peaks are investigated at RHIC and LHC energies.
Recently, we proposed a new method to introduce charge-seperated fragmentation functions (FFs) [1... more Recently, we proposed a new method to introduce charge-seperated fragmentation functions (FFs) [1]. In an earlier paper we calculated pion production in proton-proton collisions in the c.m. energy range 20-60 GeV [2]. Based on our new FFs, we calculate positive and negative pion and kaon production in proton-proton (pp) collisions at leading order (LO). The intrinsic transverse momentum distribution of partons is taken into account. We extract the best values of the width of the transverse momentum distribution of partons in pion and kaon, and calculate K/pi ratios in pp collisions. Caculated results are compared to available data. [1ex] [1] Y. Zhang and G. Fai, Bull. Am. Phys. Soc. 47, No. 2 (2002) 124. [1ex] [2] Y. Zhang et. al., Phys. Rev. C 65 034903 (2002)
With the first intriguing results from RHIC, it is a must to understand properly the background c... more With the first intriguing results from RHIC, it is a must to understand properly the background calculations of hard particle spectra. While peripheral collisions seem to agree with a scaled pQCD calculation, there is a strong deviation in the central collisions. In order to understand and characterize this discrepancy a better description of multiparticle collisions is necessary. At phenomenological level pQCD calculation may be fixed with the inclusion of the intrinsic transverse momentum of the partons [1]. However, in heavy ion collisions another effect, the nuclear or Cronin effect enhances the production of mesons in the transverse momentum range between 2 and 6 GeV/c. Analyzing available systematic data we propose a description of the Cronin effect in the energy range &surd;s=20-60 GeV. This results may be extrapolated to RHIC energies to get a reliable background description, however, one needs systematic experimental feedback at higher energies. \vspace*4mm [1] G. Papp, P. ...
A pQCD-based calculation of pion production in relativistic proton-nucleus collisions is discusse... more A pQCD-based calculation of pion production in relativistic proton-nucleus collisions is discussed. We improve the calculation from leading order (LO) [1] to an approximate next-to-leading order (NLO) with incorporation of the intrinsic transverse momentum distribution of partons. Proton-nucleus collisions are addressed in the Glauber framework, with nuclear effects. We also study the effective K factor and the effect of different factorization and fragmentation scales. Comparisons with expeimental data on the Cronin effect [3] are carried out. [1ex] [1] Y. Zhang et. al., Phys. Rev. C 65 034903 (2002) [1ex] [2] G. G. Barnafoldi et. al., J. Phys. G 27, 1767 (2000) [1ex] [3] J. W. Cronin et. al., Phys. Rev. D 11, 3105 (1975)
Non-Perturbative QCD - Proceedings of the Sixth Workshop, 2002
Recent experimental data indicate the appearance of jet-quenching effect in central Au+Au collisi... more Recent experimental data indicate the appearance of jet-quenching effect in central Au+Au collisions at RHIC. Jet energy loss is able to measure the density of colored particles in the interaction zone. We apply the GLV theory of QCD radiative energy loss to estimate the opacity, L/lambdag, of the produced gluon plasma. We show that the data can be accounted for
Electromagnetic final state interactions modifying the final energies and momenta of the products... more Electromagnetic final state interactions modifying the final energies and momenta of the products of high-energy nuclear collisions are addressed with the help of two different models. Assumptions and approximations of the two calculations are described. Results of the models are compared to experimental neutron and proton angular distributions, to cross section ratios of products with different charges but the same baryon number, and to each other. The simple model is used to account for the different behavior of the neutron and proton angular distributions when inclusive and multiplicity selected data are compared. The more elaborate prescription gives the electromagnetic effects on the energies and momenta of the individual charged particles and is applied to augment an event generator.
We investigate the influence of modified nuclear parton distribution functions (PDFs) on high-pT ... more We investigate the influence of modified nuclear parton distribution functions (PDFs) on high-pT hadron production at RHIC and LHC energies using a pQCD-improved parton model. For application at RHIC, we focus on the possible contribution of the EMC modification of the nuclear PDFs in the x > 0.3 region to the observed suppression of pi0 production at pT > 10
In this work we compare the nuclear modification factors in proton (deuteron) — nucleus collision... more In this work we compare the nuclear modification factors in proton (deuteron) — nucleus collisions at CERN SPS, FNAL and RHIC energies in a wide pT range. In these experiments the nuclear modification factor has shown an enhancement at pT ≈ 4 GeV /c. The height of this “Cronin peak” depends on the c.m. energy of the collision, as it is subject to stronger shadowing at higher energies. One of the aims of this contribution is to analyze the shadowing phenomenon at lower (2 GeV / c ≲ pT ≲ 4 GeV / c ) and intermediate (4 GeV / c ≲ pT ≲ 8 GeV / c ) transverse momentum. Different shadowing parametrizations are considered and the obtained Cronin peaks are investigated at RHIC and LHC energies.
Recently, we proposed a new method to introduce charge-seperated fragmentation functions (FFs) [1... more Recently, we proposed a new method to introduce charge-seperated fragmentation functions (FFs) [1]. In an earlier paper we calculated pion production in proton-proton collisions in the c.m. energy range 20-60 GeV [2]. Based on our new FFs, we calculate positive and negative pion and kaon production in proton-proton (pp) collisions at leading order (LO). The intrinsic transverse momentum distribution of partons is taken into account. We extract the best values of the width of the transverse momentum distribution of partons in pion and kaon, and calculate K/pi ratios in pp collisions. Caculated results are compared to available data. [1ex] [1] Y. Zhang and G. Fai, Bull. Am. Phys. Soc. 47, No. 2 (2002) 124. [1ex] [2] Y. Zhang et. al., Phys. Rev. C 65 034903 (2002)
With the first intriguing results from RHIC, it is a must to understand properly the background c... more With the first intriguing results from RHIC, it is a must to understand properly the background calculations of hard particle spectra. While peripheral collisions seem to agree with a scaled pQCD calculation, there is a strong deviation in the central collisions. In order to understand and characterize this discrepancy a better description of multiparticle collisions is necessary. At phenomenological level pQCD calculation may be fixed with the inclusion of the intrinsic transverse momentum of the partons [1]. However, in heavy ion collisions another effect, the nuclear or Cronin effect enhances the production of mesons in the transverse momentum range between 2 and 6 GeV/c. Analyzing available systematic data we propose a description of the Cronin effect in the energy range &surd;s=20-60 GeV. This results may be extrapolated to RHIC energies to get a reliable background description, however, one needs systematic experimental feedback at higher energies. \vspace*4mm [1] G. Papp, P. ...
A pQCD-based calculation of pion production in relativistic proton-nucleus collisions is discusse... more A pQCD-based calculation of pion production in relativistic proton-nucleus collisions is discussed. We improve the calculation from leading order (LO) [1] to an approximate next-to-leading order (NLO) with incorporation of the intrinsic transverse momentum distribution of partons. Proton-nucleus collisions are addressed in the Glauber framework, with nuclear effects. We also study the effective K factor and the effect of different factorization and fragmentation scales. Comparisons with expeimental data on the Cronin effect [3] are carried out. [1ex] [1] Y. Zhang et. al., Phys. Rev. C 65 034903 (2002) [1ex] [2] G. G. Barnafoldi et. al., J. Phys. G 27, 1767 (2000) [1ex] [3] J. W. Cronin et. al., Phys. Rev. D 11, 3105 (1975)
Non-Perturbative QCD - Proceedings of the Sixth Workshop, 2002
Recent experimental data indicate the appearance of jet-quenching effect in central Au+Au collisi... more Recent experimental data indicate the appearance of jet-quenching effect in central Au+Au collisions at RHIC. Jet energy loss is able to measure the density of colored particles in the interaction zone. We apply the GLV theory of QCD radiative energy loss to estimate the opacity, L/lambdag, of the produced gluon plasma. We show that the data can be accounted for
Electromagnetic final state interactions modifying the final energies and momenta of the products... more Electromagnetic final state interactions modifying the final energies and momenta of the products of high-energy nuclear collisions are addressed with the help of two different models. Assumptions and approximations of the two calculations are described. Results of the models are compared to experimental neutron and proton angular distributions, to cross section ratios of products with different charges but the same baryon number, and to each other. The simple model is used to account for the different behavior of the neutron and proton angular distributions when inclusive and multiplicity selected data are compared. The more elaborate prescription gives the electromagnetic effects on the energies and momenta of the individual charged particles and is applied to augment an event generator.
Uploads
Papers by G. Fai