2014/10/16 by J. P. Lees, V. Poireau, V. Tisserand +97
Physics and Astronomy · #Atomic physics #Branching fraction #High-Energy Particle Collisions Research #Meson #Nuclear physics #Particle physics #Particle physics theoretical and experimental studies #Physics #Quantum Chromodynamics and Particle Interactions #hep-ex
paper · pdf · doi:10.1103/physrevd.90.112010
published as Phys. Rev. D 90, 112010 (2014) · 22 pages, 9 postscript figures, submitted to PRD
arxiv created 2014/10/16 · openalex publication_date 2014/12/24 · openalex created_date 2016/06/24 · arxiv updated 2019/08/13 · openalex updated_date 2026/08/06
We use (121\ifmmode±\else\textpm\fi1) million \mathrm\ensuremathΥ(3S) and (98\ifmmode±\else\textpm\fi1) million \mathrm\ensuremathΥ(2S) mesons recorded by the BABAR detector at the PEP-II e+e^\ensuremath- collider at SLAC to perform a study of radiative transitions involving the \ensuremathχbJ(1P,2P) states in exclusive decays with \ensuremathμ+\ensuremathμ^\ensuremath-\ensuremathγ\ensuremathγ final states. We reconstruct twelve channels in four cascades using two complementary methods. In the first we identify both signal photon candidates in the electromagnetic calorimeter (EMC), employ a calorimeter timing-based technique to reduce backgrounds, and determine branching-ratio products and fine mass splittings. These results include the best observational significance yet for the \ensuremathχb0(2P)\ensuremath→\ensuremathγ\mathrm\ensuremathΥ(2S) and \ensuremathχb0(1P)\ensuremath→\ensuremathγ\mathrm\ensuremathΥ(1S) transitions. In the second method, we identify one photon candidate in the EMC and one which has converted into an e+e^\ensuremath- pair due to interaction with detector material, and we measure absolute product branching fractions. This method is particularly useful for measuring \mathrm\ensuremathΥ(3S)\ensuremath→\ensuremathγ\ensuremathχb1,2(1P) decays. Additionally, we provide the most up-to-date derived branching fractions, matrix elements and mass splittings for \ensuremathχb transitions in the bottomonium system. Using a new technique, we also measure the two lowest-order spin-dependent coefficients in the nonrelativistic QCD Hamiltonian.