Skip to main content

Measurement of the cross-section for Z → e+e- production in pp collisions at \(\sqrt{s}=7\) TeV

Abstract

A measurement of the cross-section for pp → Z → e+e is presented using data at \(\sqrt{s}=7\) TeV corresponding to an integrated luminosity of 0.94 fb−1. The process is measured within the kinematic acceptance p T > 20 GeV/c and 2 < η < 4.5 for the daughter electrons and dielectron invariant mass in the range 60–120 GeV/c 2. The cross-section is determined to be

$\sigma \left( {\mathrm{pp}\to \mathrm{Z}\to {{\mathrm{e}}^{+}}{{\mathrm{e}}^{-}}} \right)=76.0\pm 0.8\pm 2.0\pm 2.6\;\mathrm{pb}$

where the first uncertainty is statistical, the second is systematic and the third is the uncertainty in the luminosity. The measurement is performed as a function of Z rapidity and as a function of an angular variable which is closely related to the Z transverse momentum. The results are compared with previous LHCb measurements and with theoretical predictions from QCD.

References

  1. R. Thorne, A. Martin, W. Stirling and G. Watt, Parton distributions and QCD at LHCb, arXiv:0808.1847 [INSPIRE].

  2. LHCb collaboration, Inclusive W and Z production in the forward region at \(\sqrt{s}=7\) TeV, JHEP 06 (2012) 058 [arXiv:1204.1620] [INSPIRE].

    Google Scholar 

  3. LHCb collaboration, A study of the Z production cross-section in pp collisions at \(\sqrt{s}=7\) using tau final states, JHEP 01 (2013) 111 [arXiv:1210.6289] [INSPIRE].

    Google Scholar 

  4. D0 collaboration, V.M. Abazov et al., Precise study of the Z/γ boson transverse momentum distribution in \(p\overline{p}\) collisions using a novel technique, Phys. Rev. Lett. 106 (2011) 122001 [arXiv:1010.0262] [INSPIRE].

    ADS  Article  Google Scholar 

  5. A. Banfi, S. Redford, M. Vesterinen, P. Waller and T. Wyatt, Optimisation of variables for studying dilepton transverse momentum distributions at hadron colliders, Eur. Phys. J. C 71 (2011) 1600 [arXiv:1009.1580] [INSPIRE].

    ADS  Article  Google Scholar 

  6. LHCb collaboration, The LHCb detector at the LHC, 2008 JINST 3 S08005 [INSPIRE].

    ADS  Article  Google Scholar 

  7. R. Aaij et al., The LHCb trigger and its performance, arXiv:1211.3055 [INSPIRE].

  8. T. Sjöstrand, S. Mrenna and P.Z. Skands, PYTHIA 6.4 physics and manual, JHEP 05 (2006) 026 [hep-ph/0603175] [INSPIRE].

    ADS  Article  Google Scholar 

  9. I. Belyaev et al., Handling of the generation of primary events in Gauss , the LHCb simulation framework, IEEE Nucl. Sci. Symp. Conf. Rec. (2010) 1155.

  10. P.M. Nadolsky et al., Implications of CTEQ global analysis for collider observables, Phys. Rev. D 78 (2008) 013004 [arXiv:0802.0007] [INSPIRE].

    ADS  Google Scholar 

  11. GEANT4 collaboration, J. Allison et al., GEANT4 developments and applications, IEEE Trans. Nucl. Sci. 53 (2006) 270.

    ADS  Article  Google Scholar 

  12. GEANT4 collaboration, S. Agostinelli et al., GEANT4: a simulation toolkit, Nucl. Instrum. Meth. A 506 (2003) 250 [INSPIRE].

    ADS  Article  Google Scholar 

  13. M. Clemencic et al., The LHCb simulation application, Gauss: design, evolution and experience, J. Phys. Conf. Ser. 331 (2011) 032023.

    ADS  Article  Google Scholar 

  14. LHCb collaboration, Absolute luminosity measurements with the LHCb detector at the LHC, 2012 JINST 7 P01010 [arXiv:1110.2866] [INSPIRE].

    ADS  Article  Google Scholar 

  15. P. Golonka and Z. Was, PHOTOS Monte Carlo: a precision tool for QED corrections in Z and W decays, Eur. Phys. J. C 45 (2006) 97 [hep-ph/0506026] [INSPIRE].

    ADS  Article  Google Scholar 

  16. C. Carloni Calame, G. Montagna, O. Nicrosini and A. Vicini, Precision electroweak calculation of the production of a high transverse-momentum lepton pair at hadron colliders, JHEP 10 (2007) 109 [arXiv:0710.1722] [INSPIRE].

    ADS  Article  Google Scholar 

  17. Z. Was, private communication, http://annapurna.ifj.edu.pl/~wasm/phNLO.htm.

  18. R. Gavin, Y. Li, F. Petriello and S. Quackenbush, FEWZ 2.0: a code for hadronic Z production at next-to-next-to-leading order, Comput. Phys. Commun. 182 (2011) 2388 [arXiv:1011.3540] [INSPIRE].

    ADS  Article  Google Scholar 

  19. A. Martin, W. Stirling, R. Thorne and G. Watt, Parton distributions for the LHC, Eur. Phys. J. C 63 (2009) 189 [arXiv:0901.0002] [INSPIRE].

    ADS  Article  Google Scholar 

  20. R.D. Ball et al., A first unbiased global NLO determination of parton distributions and their uncertainties, Nucl. Phys. B 838 (2010) 136 [arXiv:1002.4407] [INSPIRE].

    ADS  Article  Google Scholar 

  21. H.-L. Lai et al., New parton distributions for collider physics, Phys. Rev. D 82 (2010) 074024 [arXiv:1007.2241] [INSPIRE].

    ADS  Google Scholar 

  22. P. Nadolsky et al., Progress in CTEQ-TEA PDF analysis, arXiv:1206.3321 [INSPIRE].

  23. G. Ladinsky and C. Yuan, The nonperturbative regime in QCD resummation for gauge boson production at hadron colliders, Phys. Rev. D 50 (1994) 4239 [hep-ph/9311341] [INSPIRE].

    ADS  Google Scholar 

  24. C. Balázs and C. Yuan, Soft gluon effects on lepton pairs at hadron colliders, Phys. Rev. D 56 (1997) 5558 [hep-ph/9704258] [INSPIRE].

    ADS  Google Scholar 

  25. F. Landry, R. Brock, P.M. Nadolsky and C. Yuan, Tevatron Run-1 Z boson data and Collins-Soper-Sterman resummation formalism, Phys. Rev. D 67 (2003) 073016 [hep-ph/0212159] [INSPIRE].

    ADS  Google Scholar 

  26. A. Banfi, M. Dasgupta, S. Marzani and L. Tomlinson, Predictions for Drell-Yan ϕ and Q T observables at the LHC, Phys. Lett. B 715 (2012) 152 [arXiv:1205.4760] [INSPIRE].

    ADS  Article  Google Scholar 

  27. ATLAS collaboration, Measurement of angular correlations in Drell-Yan lepton pairs to probe Z/γ boson transverse momentum at \(\sqrt{s}=7\) TeV with the ATLAS detector, arXiv:1211.6899 [INSPIRE].

  28. S. Alioli, P. Nason, C. Oleari and E. Re, NLO vector-boson production matched with shower in POWHEG, JHEP 07 (2008) 060 [arXiv:0805.4802] [INSPIRE].

    ADS  Article  Google Scholar 

  29. S. Alioli, P. Nason, C. Oleari and E. Re, Vector boson plus one jet production in POWHEG, JHEP 01 (2011) 095 [arXiv:1009.5594] [INSPIRE].

    ADS  Article  Google Scholar 

Download references

Author information

Authors and Affiliations

Authors