Jet-radius dependence of inclusive-jet cross sections in deep inelastic scattering at HERA

Abstract

Differential inclusive-jet cross sections have been measured for different jet radii in neutral current deep inelastic ep scattering for boson virtualities Q^2 > 125 GeV^2 with the ZEUS detector at HERA using an integrated luminosity of 81.7 pb^-1. Jets were identified in the Breit frame using the k_T cluster algorithm in the longitudinally inclusive mode for different values of the jet radius R. Differential cross sections are presented as functions of Q^2 and the jet transverse energy, E_T,B^jet. The dependence on R of the inclusive-jet cross section has been measured for Q^2 > 125 and 500 GeV^2 and found to be linear with R in the range studied. Next-to-leading-order QCD calculations give a good description of the measurements for 0.5 <= R <= 1. A value of alpha_s(M_Z) has been extracted from the measurements of the inclusive-jet cross-section dsigma/dQ^2 with R=1 for Q^2 > 500 GeV^2: alpha_s(M_Z) = 0.1207 +-0. AbstractDifferential inclusive-jet cross sections have been measured for different jet radii in neutral current deep inelastic ep scattering for boson virtualities Q 2 > 125 GeV 2 with the ZEUS detector at HERA using an integrated luminosity of 81.7 pb −1 . Jets were identified in the Breit frame using the k T cluster algorithm in the longitudinally inclusive mode for different values of the jet radius R. Differential cross sections are presented as functions of Q 2 and the jet transverse energy, E jet T ,B . The dependence on R of the inclusive-jet cross section has been measured for Q 2 > 125 and 500 GeV 2 and found to be linear with R in the range studied. Next-to-leading-order QCD calculations give a good description of the measurements for 0.5 R 1. A value of α s (M Z ) has been extracted from the measurements of the inclusive-jet cross section dσ/dQ 2 with R = 1 for Q 2 > 500 GeV 2 : α s (M Z ) = 0.1207 ± 0.0014(stat.) +0.0035 −0.0033 (exp.) +0.0022 −0.0023 (th.). The variation of α s with E jet T ,B is in a good agreement with the running of α s as predicted by QCD.

Inclusive-jet photoproduction at HERA and determination of

“…Table 8, indicates that the performance of the three jet algorithms is similar. These determinations are consistent with previous determinations in NC DIS [5][6][7] at HERA, with the results obtained in pp collisions [70] and have a precision comparable to those obtained in individual determinations from e + e − experiments [71]. These values are also con- sistent with the world average [63], as well as with the HERA 2004 average [72] and the HERA 2007 combined value [73].…”

“…Jet cross sections provided precise determinations of the strong coupling constant, α s , and its scale dependence. The jet observables used to test pQCD included inclusive-jet [1][2][3][4][5][6][7], dijet [1,4,[6][7][8][9] and multijet [6,7,[10][11][12] cross sections in neutral current (NC) deep inelastic ep scattering (DIS), inclusive-jet [13,14], dijet [15][16][17][18][19][20] and multijet [21,22] cross sections in photoproduction and the internal structure of jets in NC [23][24][25] and charged current [26,27] DIS. These studies also demonstrated that the k T cluster algorithm [28] in the longitudinally invariant inclusive mode [29] results in the smallest uncertainties in the reconstruction of jets in ep collisions.…”

Measurement of multijet production in $${e\!\!\;p}$$ e p collisions at high $$\varvec{Q^2}$$ Q 2 and determination of the strong coupling $$\varvec{{\alpha _s}} $$ α s

“…MC studies of the reconstruction performance and comparisons between jets on detector, hadron and parton level indicate that R 0 = 1 is a good choice for the phase space of this analysis. This is also in agreement with the result reported in [37]. The transverse component of the jet four-vector with respect to The jet axis is transformed to the laboratory rest frame, and jets with a pseudorapidity in the laboratory frame of −1.5 < η jet lab < 2.75 are selected.…”

The 2009 world average of α s

“…In a recent summary and combination [63] of precision measurements at HERA, values of α s where determined from fits of NLO QCD predictions to data of inclusive jet cross sections in neutral current deep inelastic scattering at high Q 2 [64][65][66]. The overall combined result,…”