Study of hard double-parton scattering in four-jet events in $pp$ collisions at $\sqrt{s} = 7$ TeV with the ATLAS experiment

G. Aad 1 M. Alstaty 1 M. Barbero 1 A. Calandri 1 T.P. Calvet 1 Y. Coadou 1 C. Diaconu 1 F. Djama 1 V. Ellajosyula 1 L. Feligioni 1 A. Hadef 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 1 D. Madaffari 1 E. Monnier 1 S. Muanza 1 E. Nagy 1 P. Pralavorio 1 Y. Rodina 1 A. Rozanov 1 M. Talby 1 T. Theveneaux-Pelzer 1 R.E. Ticse Torres 1 S. Tisserant 1 J. Toth 1 F. Touchard 1 L. Vacavant 1 Chen Wang 1 D. Boumediene 2 E. Busato 2 D. Calvet 2 S. Calvet 2 A.R. Chomont 2 J. Donini 2 S. Ganguly 2 Ph. Gris 2 R. Madar 2 D. Pallin 2 S.M. Romano Saez 2 C. Santoni 2 D. Simon 2 F. Vazeille 2 N. Berger 3 M. Delmastro 3 L. Di Ciaccio 3 S. Elles 3 K. Grevtsov 3 T. Guillemin 3 T. Hryn’ova 3 S. Jézéquel 3 I. Koletsou 3 R. Lafaye 3 Jérémy Lévêque 3 P. Mastrandea 3 E. Sauvan 3 B.H. Smart 3 T. Todorov 3 I. Wingerter-Seez 3 E. Yatsenko 3 S. Albrand 4 S. Berlendis 4 A. Bethani 4 C. Camincher 4 J. Collot 4 S. Crépé-Renaudin 4 P.A. Delsart 4 C. Gabaldon 4 M.H. Genest 4 P.O.J. Gradin 4 J.Y. Hostachy 4 F. Ledroit-Guillon 4 A. Lleres 4 A. Lucotte 4 F. Malek 4 E. Petit 4 J. Stark 4 B. Trocmé 4 M. Wu 4 G. Rahal 5
Abstract : Inclusive four-jet events produced in proton--proton collisions at a centre-of-mass energy of $\sqrt{s} = 7$ TeV are analysed for the presence of hard double-parton scattering using data corresponding to an integrated luminosity of 37.3 pb$^{-1}$, collected with the ATLAS detector at the LHC. The contribution of hard double-parton scattering to the production of four-jet events is extracted using an artificial neural network, assuming that hard double-parton scattering can be approximated by an uncorrelated overlaying of dijet events. For events containing at least four jets with transverse momentum $p_{\mathrm{T}} \geq 20$ GeV and pseudorapidity $\eta \leq 4.4$, and at least one having $p_{\mathrm{T}} \geq 42.5$ GeV, the contribution of hard double-parton scattering is estimated to be $f_{\mathrm{DPS}} = 0.092 ^{+0.005}_{-0.011} (\mathrm{stat.}) ^{+0.033}_{-0.037} (\mathrm{syst.})$. After combining this measurement with those of the inclusive dijet and four-jet cross-sections in the appropriate phase space regions, the effective overlap area between the interacting protons, $\sigma_{\mathrm{eff}}$, was determined to be $\sigma_{\mathrm{eff}} = 14.9 ^{+1.2}_{-1.0} (\mathrm{stat.}) ^{+5.1}_{-3.8} (\mathrm{syst.})$ mb. This result is consistent within the quoted uncertainties with previous measurements of $\sigma_{\mathrm{eff}}$, performed at centre-of-mass energies between 63 GeV and 8 TeV using various final states, and it corresponds to $21^{+7}_{-6}$% of the total inelastic cross-section measured at $\sqrt{s} = 7$ TeV. The distributions of the observables sensitive to the contribution of hard double-parton scattering, corrected for detector effects, are also provided.
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Article dans une revue
Journal of High Energy Physics, Springer Verlag (Germany), 2016, 11, pp.110. 〈10.1007/JHEP11(2016)110〉
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Soumis le : lundi 8 août 2016 - 08:43:43
Dernière modification le : lundi 22 octobre 2018 - 09:42:01

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G. Aad, M. Alstaty, M. Barbero, A. Calandri, T.P. Calvet, et al.. Study of hard double-parton scattering in four-jet events in $pp$ collisions at $\sqrt{s} = 7$ TeV with the ATLAS experiment. Journal of High Energy Physics, Springer Verlag (Germany), 2016, 11, pp.110. 〈10.1007/JHEP11(2016)110〉. 〈in2p3-01352446〉

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