The subjet multiplicity has been measured in neutral current e(+) p interactions at Q(2) > 125 GeV(2) with the ZEUS detector at HERA using an integrated luminosity of 38.6 pb(-1). Jets were identified in the laboratory frame using the longitudinally invariant k(T) cluster algorithm. The number of jet-like substructures within jets, known as the subjet multiplicity, is defined as the number of clusters resolved in a jet by reapplying the jet algorithm at a smaller resolution scale y(cut). Measurements of the mean subjet multiplicity, <n(sbj)>, for jets with transverse energies E(T,jet) > 15 GeV are presented. Next-to-leading-order perturbative QCD calculations describe the measurements well. The value of alpha(s) (M(Z)), determined from <n(sbj)> at y(cut) = 10(-2) for jets with 25 < E(T,jet) < 71 GeV, is alpha(s) (M(Z)) = 0.1187 +/- 0.0017(stat.)(-0.0009)(+0.0024)(syst.)(-0.0076)(+0.0093)(th.). (C) 2003 Published by Elsevier Science B.V.

Measurement of subjet multiplicities in neutral current deep inelastic scattering at HERA and determination of alpha(s)

MASTROBERARDINO, Anna;Tassi E;
2003-01-01

Abstract

The subjet multiplicity has been measured in neutral current e(+) p interactions at Q(2) > 125 GeV(2) with the ZEUS detector at HERA using an integrated luminosity of 38.6 pb(-1). Jets were identified in the laboratory frame using the longitudinally invariant k(T) cluster algorithm. The number of jet-like substructures within jets, known as the subjet multiplicity, is defined as the number of clusters resolved in a jet by reapplying the jet algorithm at a smaller resolution scale y(cut). Measurements of the mean subjet multiplicity, , for jets with transverse energies E(T,jet) > 15 GeV are presented. Next-to-leading-order perturbative QCD calculations describe the measurements well. The value of alpha(s) (M(Z)), determined from at y(cut) = 10(-2) for jets with 25 < E(T,jet) < 71 GeV, is alpha(s) (M(Z)) = 0.1187 +/- 0.0017(stat.)(-0.0009)(+0.0024)(syst.)(-0.0076)(+0.0093)(th.). (C) 2003 Published by Elsevier Science B.V.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11770/146356
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