Study of hard double-parton scattering in four-jet events in pp collisions at √s = 7 TeV with the ATLAS experiment

Journal of High Energy Physics 2016.11 (2016): 110 reproduced by permission of Scuola Internazionale Superiore di Studi Avanzati (SISSA)Artículo escrito por muchos autores, sólo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración y los autores que firman como pertenecientes a la UAMInclusive four-jet events produced in proton-proton collisions at a centre-ofmass
energy of √
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 pT ≥ 20 GeV and
pseudorapidity |η| ≤ 4.4, and at least one having pT ≥ 42.5 GeV, the contribution of hard
double-parton scattering is estimated to be fDPS = 0.092 +0.005
−0.011 (stat.)
+0.033
−0.037 (syst.). After
combining this measurement with those of the inclusive dijet and four-jet cross-sections in
the appropriate phase space regions, the effective cross-section, σeff, was determined to be
σeff = 14.9
+1.2
−1.0
(stat.)
+5.1
−3.8
(syst.) mb. This result is consistent within the quoted uncertainties
with previous measurements of σeff, 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 √
s = 7 TeV. The distributions of the observables sensitive
to the contribution of hard double-parton scattering, corrected for detector effects, are also
providedWe acknowledge the support of ANPCyT, Argentina; YerPhI, Armenia; ARC, Australia;
BMWFW and FWF, Austria; ANAS, Azerbaijan; SSTC, Belarus; CNPq and FAPESP, Brazil; NSERC, NRC and CFI, Canada; CERN; CONICYT, Chile; CAS, MOST and NSFC, China; COLCIENCIAS, Colombia; MSMT CR, MPO CR and VSC CR, Czech Republic; DNRF and DNSRC, Denmark; IN2P3-CNRS, CEA-DSM/IRFU, France; GNSF, Georgia; BMBF, HGF, and MPG, Germany; GSRT, Greece; RGC, Hong Kong SAR, China; ISF, I-CORE and Benoziyo Center, Israel; INFN, Italy; MEXT and JSPS, Japan; CNRST, Morocco; FOM and NWO, Netherlands; RCN, Norway; MNiSW and NCN, Poland; FCT, Portugal; MNE/IFA, Romania; MES of Russia and NRC KI, Russian Federation; JINR; MESTD, Serbia; MSSR, Slovakia; ARRS and MIZS, Slovenia; DST/NRF, South Africa; MINECO, Spain; SRC and Wallenberg Foundation, Sweden; SERI, SNSF and Cantons of Bern and Geneva, Switzerland; MOST, Taiwan; TAEK, Turkey; STFC, United Kingdom; DOE and NSF, United States of America. In addition, individual groups and members have received support from BCKDF, the Canada Council, CANARIE, CRC, Compute Canada, FQRNT, and the Ontario Innovation Trust, Canada; EPLANET, ERC, FP7, Horizon 2020 and Marie Sklodowska- Curie Actions, European Union; Investissements d’Avenir Labex and Idex, ANR, Région Auvergne and Fondation Partager le Savoir, France; DFG and AvH Foundation, Germany; Herakleitos, Thales and Aristeia programmes cofinanced by EU-ESF and the Greek NSRF; BSF, GIF and Minerva, Israel; BRF, Norway; Generalitat de Catalunya, Generalitat Valenciana, Spain; the Royal Society and Leverhulme Trust, United Kingdo