Measurement of exclusive $\gamma\gamma\rightarrow \ell^+\ell^-$ production in proton-proton collisions at $\sqrt{s} = 7$ TeV with the ATLAS detector

G. Aad 1 Z. Barnovska 2 N. Berger 2 M. Delmastro 2 L. Di Ciaccio 2 S. Elles 2 T. Hryn’ova 2 S. Jézéquel 2 I. Koletsou 2 R. Lafaye 2 J. Leveque 2 N. Massol 2 G. Sauvage 2 E. Sauvan 2 O. Simard 2 T. Todorov 2 I. Wingerter-Seez 2 E. Yatsenko 2 G . Rahal 3 M.K. Ayoub 4 A. Bassalat 4 C. Becot 4 S. Binet 4 C. Bourdarios 4 J.B. de Vivie De Regie 4 D. Delgove 4 L. Duflot 4 M. Escalier 4 L. Fayard 4 D. Fournier 4 E.L. Gkougkousis 4 J.-F. Grivaz 4 T. Guillemin 4 F. Hariri 4 S. Henrot-Versillé 4 J. Hrivnac 4 L. Iconomidou-Fayard 4 M. Kado 4 A. Lounis 4 N. Makovec 4 N. Morange 4 C. Nellist 4 L. Poggioli 4 P. Puzo 4 A. Renaud 4 D. Rousseau 4 G. Rybkin 4 A.C. Schaffer 4 E. Scifo 4 L. Serin 4 S. Simion 4 R. Tanaka 4 H.L. Tran 4 D. Zerwas 4 Zhongkai Zhang 4 Y. Zhao 4 S. Albrand 5 J. Brown 5 J. Collot 5 S. Crépé-Renaudin 5 P.A. Delsart 5 C. Gabaldon 5 M.H. Genest 5 J.Y. Hostachy 5 F. Ledroit-Guillon 5 A. Lleres 5 A. Lucotte 5 F. Malek 5 C. Monini 5 J. Stark 5 B. Trocmé 5 M. Wu 5 D. Boumediene 6 Emmanuel Busato 6 D. Calvet 6 S. Calvet 6 J. Donini 6 E. Dubreuil 6 G. Gilles 6 Ph. Gris 6 H. Liao 6 R. Madar 6 D. Pallin 6 S.M. Romano Saez 6 C. Santoni 6 D. Simon 6 Timothée Theveneaux-Pelzer 6 F. Vazeille 6 L. Alio 1 M. Barbero 1 Y. Coadou 1 C. Diaconu 1 S. Diglio 1 F. Djama 1 O. Duccu 1 L. Feligioni 1 J. Gao 1 G.D. Hallewell 1 F. Hubaut 1 S.J. Kahn 1 E. B. F. G. Knoops 1 E. Le Guirriec 1 J. Liu 1 K. Liu D. Madaffari 1 K. Mochizuki 1 E. Monnier 1 S. Muanza 1 Y. Nagai 1 E. Nagy 1 P. Pralavorio 1 A. Rozanov 1 T. Serre 1 M. Talby 1 R.E. Ticse Torres 1 E. Tiouchichine 1 S. Tisserant 1 J. Toth 1 F. Touchard 1 L. Vacavant 1
Abstract : This Letter reports a measurement of the exclusive $\gamma\gamma\rightarrow \ell^+\ell^- (\ell=e, \mu)$ cross-section in proton-proton collisions at a centre-of-mass energy of 7 TeV by the ATLAS experiment at the LHC, based on an integrated luminosity of $4.6$ fb$^{-1}$. For the electron or muon pairs satisfying exclusive selection criteria, a fit to the dilepton acoplanarity distribution is used to extract the fiducial cross-sections. The cross-section in the electron channel is determined to be $\sigma_{\gamma\gamma\rightarrow e^+e^-}^{\mathrm{excl.}} = 0.428 \pm 0.035 (\mathrm{stat.}) \pm 0.018 (\mathrm{syst.})$ pb for a phase-space region with invariant mass of the electron pairs greater than 24 GeV, in which both electrons have transverse momentum $p_\mathrm{T}>12$ GeV and pseudorapidity $|\eta|<2.4$. For muon pairs with invariant mass greater than 20 GeV, muon transverse momentum $p_\mathrm{T}>10$ GeV and pseudorapidity $|\eta|<2.4$, the cross-section is determined to be $\sigma_{\gamma\gamma\rightarrow \mu^+\mu^- }^{\mathrm{excl.}} = 0.628 \pm 0.032 (\mathrm{stat.}) \pm 0.021 (\mathrm{syst.})$ pb. When proton absorptive effects due to the finite size of the proton are taken into account in the theory calculation, the measured cross-sections are found to be consistent with the theory prediction.
Type de document :
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Physics Letters B, Elsevier, 2015, 749, pp.242-261. 〈10.1016/j.physletb.2015.07.069〉
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Soumis le : lundi 29 juin 2015 - 15:37:04
Dernière modification le : mardi 13 février 2018 - 13:28:06

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G. Aad, Z. Barnovska, N. Berger, M. Delmastro, L. Di Ciaccio, et al.. Measurement of exclusive $\gamma\gamma\rightarrow \ell^+\ell^-$ production in proton-proton collisions at $\sqrt{s} = 7$ TeV with the ATLAS detector. Physics Letters B, Elsevier, 2015, 749, pp.242-261. 〈10.1016/j.physletb.2015.07.069〉. 〈in2p3-01169510〉

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