Measurement of the Inclusive Jet Cross Section inppCollisions ats=7  TeV

Abstract

The inclusive jet cross section is measured in pp collisions with a center-of-mass energy of 7 TeV at the Large Hadron Collider using the CMS experiment. The data sample corresponds to an integrated luminosity of 34 pb À1 . The measurement is made for jet transverse momenta in the range 18-1100 GeVand for absolute values of rapidity less than 3. The measured cross section extends to the highest values of jet p T ever observed and, within the experimental and theoretical uncertainties, is generally in agreement with next-to-leadingorder perturbative QCD predictions. DOI: 10.1103/PhysRevLett.107.132001 PACS numbers: 13.85.Àt, 12.38.Bx The measurement of the inclusive jet cross section is a benchmark of the standard model (SM) at hadron colliders [1,2]. At the Large Hadron Collider (LHC), jets produced in the high center-of-mass energy collisions test the SM at the smallest distance scales presently possible can constrain parton momentum distributions in the proton and are sensitive to the strong coupling constant. Significant deviations from predictions of the inclusive jet cross section at high transverse momentum p T could also be an indication of new phenomena beyond the SM. Results from the Tevatron p " p collider demonstrate agreement with nextto-leading-order (NLO) theoretical predictions from perturbative quantum chromodynamics (pQCD) for jets in the approximate p T range of 50-700 GeV, using about 1 fb Early results from the ATLAS Collaboration for jets in the p T range 60-600 GeV, based on a 17 pb À1 data sample of pp collisions at ffiffi ffi s p ¼ 7 TeV at the LHC [6], also indicate agreement with theoretical predictions. Using a data sample corresponding to 34 pb À1 of integrated luminosity from pp collisions recorded by the CMS detector at the LHC with ffiffi ffi s p ¼ 7 TeV, we significantly extend the p T range from previous measurements of the inclusive jet p T spectrum to 18-1100 GeV and for rapidities jyj < 3:0. The rapidity y is defined as y ¼ 1 2 ln½ðE þ p z Þ=ðE À p z Þ, where E is the jet energy and p z is the component of the jet momentum along the beam axis. The inclusive jet cross section is defined as d 2 jet =ðdp T dyÞ ¼ N jet = ðÁp T ÁyÞ½1=ðLÞ, where N jet is the number of jets per bin, Áp T and Áy are the bin widths in p T and y, L is the total integrated luminosity, and is the product of event and jet selection efficiencies. All jets with p T > 18 GeV in a proton-proton collision event are used in the measurement. In this Letter, the inclusive jet cross section is compared with theoretical predictions at NLO in pQCD.The CMS detector has silicon pixel and microstrip trackers covering pseudorapidities up to jj ¼ 2:5, where ¼ À ln½tanð=2Þ and is the polar angle relative to the counterclockwise proton beam direction. Together with a 3.8 T solenoid, the trackers enable track reconstruction down to transverse momenta of about 100 MeV and a resolution of about 1% at 100 GeV. A high-granularity electromagnetic crystal calorimeter (ECAL) extends up to jj ¼ 3:0 and has an energy resolution o...

Measurement of the inclusive jet cross-section in pp collisions at $\sqrt{s}=2.76\ \mbox{TeV}$ and comparison to the inclusive jet cross-section at $\sqrt{s} =7\ \mbox{TeV}$ using the ATLAS detector

“…The ATLAS Collaboration has presented early measurements of the inclusive jet cross-section at based on a dataset with an integrated luminosity of 17 nb −1 for jets with a transverse momentum of 60≤ p T <600 GeV and a rapidity1 of | y |<2.8 [24], as well as for the entire dataset of 37 pb −1 taken in 2010 for jets with 20≤ p T <1500 GeV and | y |<4.4 [25]. The CMS Collaboration has presented results in the kinematic range of 18≤ p T <1100 GeV and | y |<3 in a dataset of 34 pb −1 [26], in the range of 35≤ p T <150 GeV and 3.2<| y |<4.7 using 3.1 pb −1 [27], and for 0.1≤ p T <2 TeV and | y |<2.5 using 5.0 fb −1 [28]. These data are found to be generally well described by next-to-leading order (NLO) pQCD calculations, corrected for non-perturbative effects from hadronisation and the underlying event.…”

Search for contact interactions using the inclusive jetpTspectrum inppcollisions ats=Chatrchyan1, Khachatryan2, Sirunyan3 et al. 2013Phys. Rev. DSelf Cite170140View full textAdd to dashboardCite

“…(4). Nonperturbative corrections are less than 1% for transverse momenta above $400 GeV [30], negligible compared with other uncertainties, and are therefore not applied to our analysis.…”

“…The jet trigger efficiency is constant, $98:8%, above $400 GeV, well below the search region. Events with hadron calorimeter noise are removed [29] and each selected event must have a primary vertex within 24 cm of the geometric center of the detector along the z axis and within 0.2 cm in the transverse x-y plane, defined by criteria described in [30]. The search is restricted to jj < 0:5 where the effects of contact interactions are predicted to be the largest [1][2][3][4].…”

“…The contributions from all uncertainty components are summed to obtain an overall shift in the jet p T . From studies of dijet asymmetry and photon þ jet p T balancing, the uncertainty in the jet energy resolution is estimated to be 10% in the pseudorapidity range jj < 0:5 [30]. We sample the jet energy resolution using a procedure identical to that used to sample the jet energy scale but using a single Gaussian variate.…”

Identification of b-quark jets in the CMS experiment

“…The average fraction of gluon jets depends on the details of the parton density and hadronization functions used in the simulation. An uncertainty of ±20% is extracted from the comparison of simulation with data [47].…”