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)
G. Aad
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Y. Coadou
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D. Boumediene
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D. Calvet
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N. Berger
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T. Hryn’ova
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S. Jézéquel
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S. Crépé-Renaudin
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M.H. Genest
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F. Ledroit-Guillon
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F. Malek
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B. Trocmé
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- IdRef : 139039872
Résumé
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.