The production of Upsilon(1S), Upsilon(2S) and Upsilon(3S) mesons in proton-proton collisions at the centre-of-mass energy of root s = 7 TeV is studied with the LHCb detector. The analysis is based on a data sample of 25 pb(-1) collected at the Large Hadron Collider. The Gamma mesons are reconstructed in the decay mode Gamma -> mu(+)mu(-) and the signal yields are extracted from a fit to the mu(+)mu(-) invariant mass distributions. The differential production cross-sections times dimuon branching fractions are measured as a function of the Gamma transverse momentum p(T) and rapidity y, over the range p(T) < 15 GeV/c and 2.0 < y < 4.5. The cross-sections times branching fractions, integrated over these kinematic ranges, are measured to be sigma(pp -> Upsilon(1S) X) x B(Upsilon(1S) -> mu(+)mu(-)) = 2.29+/-0.01+/-0.10(-0.37)(+0.19) nb, sigma(pp -> Upsilon(2S) X x B(Upsilon(2S) -> mu(+)mu(-)) = 0.562+/-0.007+/-0.023(-0.092)(+0.048) nb, sigma(pp -> Upsilon(3S) X) x B(Upsilon(3S) -> mu(+)mu(-)) = 0.283+/-0.005+/-0.012(-0.048)(+0.025) nb, where the first uncertainty is statistical, the second systematic and the third is due to the unknown polarisation of the three Upsilon states.
Measurement of Upsilon production in pp collisions at root s=7 TeV
VELTRI, MICHELE;
2012
Abstract
The production of Upsilon(1S), Upsilon(2S) and Upsilon(3S) mesons in proton-proton collisions at the centre-of-mass energy of root s = 7 TeV is studied with the LHCb detector. The analysis is based on a data sample of 25 pb(-1) collected at the Large Hadron Collider. The Gamma mesons are reconstructed in the decay mode Gamma -> mu(+)mu(-) and the signal yields are extracted from a fit to the mu(+)mu(-) invariant mass distributions. The differential production cross-sections times dimuon branching fractions are measured as a function of the Gamma transverse momentum p(T) and rapidity y, over the range p(T) < 15 GeV/c and 2.0 < y < 4.5. The cross-sections times branching fractions, integrated over these kinematic ranges, are measured to be sigma(pp -> Upsilon(1S) X) x B(Upsilon(1S) -> mu(+)mu(-)) = 2.29+/-0.01+/-0.10(-0.37)(+0.19) nb, sigma(pp -> Upsilon(2S) X x B(Upsilon(2S) -> mu(+)mu(-)) = 0.562+/-0.007+/-0.023(-0.092)(+0.048) nb, sigma(pp -> Upsilon(3S) X) x B(Upsilon(3S) -> mu(+)mu(-)) = 0.283+/-0.005+/-0.012(-0.048)(+0.025) nb, where the first uncertainty is statistical, the second systematic and the third is due to the unknown polarisation of the three Upsilon states.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
