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

Collaboration
Oct 14, 2014
20 pages
Published in:
  • Phys.Rev.D 90 (2014) 11, 112010
  • Published: Dec 24, 2014
e-Print:
Report number:
  • BABAR-PUB-14-005,
  • SLAC-PUB-16123
Experiments:

Citations per year

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Abstract: (APS)

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.

Note:
  • 22 pages, 9 postscript figures, submitted to PRD
  • 13.20.Gd
  • 14.40.Pq
  • 14.65.Fy
  • electron positron: annihilation
  • electron positron: colliding beams
  • upsilon mesons: electroproduction
  • upsilon mesons: radiative decay
  • excited state
  • bottomonium: radiative decay
  • bottomonium: branching ratio: measured