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Bottomonium spectroscopy and radiative transitions involving the chi_bJ(1P,2P) states at BABAR
Journal article   Open access   Peer reviewed

Bottomonium spectroscopy and radiative transitions involving the chi_bJ(1P,2P) states at BABAR

J. P Lees and BaBar Collaboration
Physical review. D, Particles, fields, gravitation, and cosmology, Vol.90(11), 112010
10/14/2014
DOI: 10.1103/PhysRevD.90.112010
url
https://doi.org/10.1103/PhysRevD.90.112010View
Published (Version of record) Open Access

Abstract

We use (121±1) million Υ(3S) and (98±1) million Υ(2S) mesons recorded by the BABAR detector at the PEP-II e+e− collider at SLAC to perform a study of radiative transitions involving the χbJ(1P,2P) states in exclusive decays with μ+μ−γγ 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 χb0(2P)→γΥ(2S) and χb0(1P)→γΥ(1S) transitions. In the second method, we identify one photon candidate in the EMC and one which has converted into an e+e− pair due to interaction with detector material, and we measure absolute product branching fractions. This method is particularly useful for measuring Υ(3S)→γχb1,2(1P) decays. Additionally, we provide the most up-to-date derived branching fractions, matrix elements and mass splittings for χb transitions in the bottomonium system. Using a new technique, we also measure the two lowest-order spin-dependent coefficients in the nonrelativistic QCD Hamiltonian.
Physics - High Energy Physics - Experiment

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