PT Journal
AU ATLAS Collaboration (Aad, Gea
   Amoros, G
   Cabrera Urban, S
   Castillo Gimenez, V
   Costa, MJ
   Escobar, C
   Ferrer, A
   Fiorini, L
   Fuster, J
   Garcia, C
   Gonzalez de la Hoz, S
   Hernandez Jimenez, Y
   Higon-Rodriguez, E
   Irles Quiles, A
   Kaci, M
   Lacasta, C
   Lacuesta, VR
   Marti-Garcia, S
   Miñano, M
   Mitsou, VA
   Moles-Valls, R
   Moreno Llacer, M
   Oliver Garcia, E
   Perez Garcia-Estañ, MT
   Ros, E
   Salt, J
   Solans, CA
   Soldevila, U
   Sanchez, J
   Torro Pastor, E
   Valladolid Gallego, E
   Valls Ferrer, JA
   Villaplana Perez, M
   Vos, M
   Wildauer, A
TI Measurement of the gamma(1S) production cross-section in pp collisions at sqrt(s)=7 TeV in ATLAS ATLAS Collaboration
SO Physics Letters B
JI Phys. Lett. B
PY 2011
BP 9
EP 27
VL 705
IS 1-2
DI 10.1016/j.physletb.2011.09.092
LA English
AB A measurement of the cross-section for gamma(1S) -> mu(+)mu(-) production in proton-proton collisions at centre of mass energy of 7 TeV is presented. The cross-section is measured as a function of the gamma(1S) transverse momentum in two bins of rapidity, vertical bar y(gamma(1S))vertical bar < 1.2 and 1.2 < vertical bar y(gamma(1S))vertical bar < 2.4. The measurement requires that both muons have transverse momentum p(T)(mu) > 4 GeV and pseuclorapidity vertical bar eta(mu)vertical bar < 2.5 in order to reduce theoretical uncertainties on the acceptance, which depend on the poorly known polarisation. The results are based on an integrated luminosity of 1.13 pb(-1), collected with the ATLAS detector at the Large Hadron Collider. The cross-section measurement is compared to theoretical predictions: it agrees to within a factor of two with a prediction based on the NRQCD model including colour-singlet and colour-octet matrix elements as implemented in PYTHIA while it disagrees by up to a factor of ten with the next-to-leading order prediction based on the colour-singlet model.
ER