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Isolating vector boson scattering at the CERN LHC: Gauge cancellations and the equivalent vector boson approximation versus complete calculations

Elena Accomando, Alessandro Ballestrero, Aissa Belhouari, and Ezio Maina
Phys. Rev. D 74, 073010 – Published 20 October 2006
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  • INTRODUCTION
  • VV SCATTERING AND GAUGE INVARIANCE
  • THE EFFECTIVE VECTOR BOSON APPROXIMATION
  • EVBA APPLICATION TO THE PP→us→dcW+W− PRO…
  • COMPARISON BETWEEN EVBA AND EXACT…
  • THE LARGE INVARIANT MASS REGION
  • CONCLUSIONS
  • ACKNOWLEDGEMENTS
  • APPENDICES
    • References

    Abstract

    We have studied the possibility of extracting the W+W−→W+W− signal using the process us→cdW+W− as a test case. We have investigated numerically the strong gauge cancellations between signal and irreducible background, critically analyzing the reliability of the equivalent vector boson approximation which is commonly used to define the signal. Complete matrix elements are necessary to study electroweak symmetry breaking effects at high WW invariant mass.

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    • Received 18 August 2006

    DOI:https://doi.org/10.1103/PhysRevD.74.073010

    ©2006 American Physical Society

    Authors & Affiliations

    Elena Accomando*, Alessandro Ballestrero†, Aissa Belhouari‡, and Ezio Maina§

    • INFN, Sezione di Torino and Dipartimento di Fisica Teorica, Università di Torino, Via Giuria 1, 10125 Torino, Italy

    • *Electronic address: accomand@to.infn.it
    • †Electronic address: ballestr@to.infn.it
    • ‡Electronic address: belhouar@to.infn.it
    • §Electronic address: maina@to.infn.it

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    Issue

    Vol. 74, Iss. 7 — 1 October 2006

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    Images

    • Figure 1
      Figure 1
      Main diagram topologies for the process us→cdW+W−.Reuse & Permissions
    • Figure 2
      Figure 2
      Distribution of dσ/dMWW for the process PP→us→cdW+W− for all diagrams, WW diagrams, and their ratio in unitary, Feynman, and axial gauges in the infinite Higgs mass limit. The unitary gauge data in the left-hand plot have been divided by 20 for better presentation.Reuse & Permissions
    • Figure 3
      Figure 3
      Double differential distributions of dσ/dt1dt2  (pb/GeV2) with t1,2=−(pu,s−pd,c)2 for the process PP→us→dcW+W−, using all diagrams (a) or only the WW fusion subset in axial gauge (b). The two plots in the central row represent the ratio WW/all in the axial gauge as a function of t1, t2 for the total region (c) and for small t’s (d). For comparison we also show the distributions of the WW fusion subset in the unitary (e) and Feynman (f) gauges. All invariants are in GeV.Reuse & Permissions
    • Figure 4
      Figure 4
      WW invariant mass distribution M(WW) for the process us→dcW+W− with EVBA (black solid curve) and with exact complete computation (red dashed curve) for the infinite Higgs mass case (left panel) and Mh=250  GeV (right panel) at the LHC.Reuse & Permissions
    • Figure 5
      Figure 5
      The WW invariant mass distribution with different θ cuts with EVBA (solid curves) and with the exact calculation (dashed curves). From top to bottom, θc=10° (black), 30° (red), 60° (blue). The CM energy is s=1  TeV and Mh=500  GeV.Reuse & Permissions
    • Figure 6
      Figure 6
      The WW invariant mass distribution in PP→us→cdW+W− at the LHC for the infinite Higgs mass case (solid lines) and for Mh=200  GeV (dashed lines). The two intermediate (red) lines have been obtained imposing the set of cuts described in the text. The two lowest (blue) lines refer to the process PP→us→cdμ−ν¯μe+νe; in this case further acceptance cuts have been imposed on the charged leptons: El>20  GeV, pTl>10  GeV, |ηl|<3.Reuse & Permissions
    • Figure 7
      Figure 7
      Distribution of the pseudorapidity difference between the two W’s for us→dcW+W− at the LHC for the infinite Higgs mass case (solid line) and Mh=200  GeV (dashed line).Reuse & Permissions
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