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Title: Bottomonium spectroscopy and radiative transitions involving the χbJ(1P,2P) states at BABAR
Author: Graugés Pous, Eugeni
BABAR Collaboration
Keywords: Física de partícules
Particle physics
Issue Date: 24-Dec-2014
Publisher: American Physical Society
Abstract: We use ( 121 ± 1 ) million Υ ( 3 S ) and ( 98 ± 1 ) million Υ ( 2 S ) mesons recorded by the BABAR detector at the PEP-II e + e − collider at SLAC to perform a study of radiative transitions involving the χ b J ( 1 P , 2 P ) states in exclusive decays with μ + μ − γ γ 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 χ b 0 ( 2 P ) → γ Υ ( 2 S ) and χ b 0 ( 1 P ) → γ Υ ( 1 S ) 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 ( 3 S ) → γ χ b 1 , 2 ( 1 P ) decays. Additionally, we provide the most up-to-date derived branching fractions, matrix elements and mass splittings for χ b transitions in the bottomonium system. Using a new technique, we also measure the two lowest-order spin-dependent coefficients in the nonrelativistic QCD Hamiltonian.
Note: Reproducció del document publicat a:
It is part of: Physical Review D, 2014, vol. 90, num. 11, p. 112010
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ISSN: 1550-7998
Appears in Collections:Articles publicats en revistes (Física Quàntica i Astrofísica)

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