PT Journal AU ATLAS Collaboration (Aad, Gea Alvarez Piqueras, D Cabrera Urban, S Castillo Gimenez, V Costa, MJ Fernandez Martinez, P Ferrer, A Fiorini, L Fuster, J Garcia, C Garcia Navarro, JE Gonzalez de la Hoz, S Hernandez Jimenez, Y Higon-Rodriguez, E Irles Quiles, A Jimenez Pena, J Kaci, M King, M Lacasta, C Lacuesta, VR Marti-Garcia, S Mitsou, VA Oliver Garcia, E Pedraza Lopez, S Perez Garcia-Estañ, MT Romero Adam, E Ros, E Salt, J Sanchez Martinez, V Soldevila, U Sanchez, J Valero, A Valladolid Gallego, E Valls Ferrer, JA Vos, M TI Determination of the Ratio of b-Quark Fragmentation Fractions f(s)/f(d) in pp Collisions at root s=7 TeV with the ATLAS Detector SO Physical Review Letters JI Phys. Rev. Lett. PY 2015 BP 262001 - 18pp VL 115 IS 26 DI 10.1103/PhysRevLett.115.262001 LA English AB With an integrated luminosity of 2.47 fb(-1) recorded by the ATLAS experiment at the LHC, the exclusive decays B-s(0) -> J/psi phi and B-d(0) -> J/psi K*(0) of B mesons produced in pp collisions at root s = 7 TeV are used to determine the ratio of fragmentation fractions f(s)/f(d). From the observed B-s(0) -> J/psi phi and B-d(0) -> J/psi K*(0) yields, the quantity (f(s)/f(d))[B(B-s(0) -> J/psi phi)/B(B-d(0) -> J/psi K*(0) )] is measured to be 0.199 +/- 0.004(stat) +/- 0.008(syst). Using a recent theory prediction for [B(B-s(0) -> J/psi phi)/B(B-d(0) -> J/psi K*(0))] yields (f(s)/f(d)) = 0.240 +/- 0.004(stat) +/- 0.010(syst) +/- 0.017(th). This result is based on a new approach that provides a significant improvement of the world average. ER