Differential branching fraction and angular analysis of Λ[0 over b] → Λμ[superscript +] μ[superscript −] decays
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Aaij-2015-Differential branchi.pdf
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Author(s)
Counts, Ian Thomas Hunt
Williams, Michael
Ilten, Philip J
Date Issued
June 2015
Journal
Journal of High Energy Physics
Publisher
Springer-Verlag
Citation
Aaij, R., B. Adeva, M. Adinolfi, A. Affolder, Z. Ajaltouni, S. Akar, J. Albrecht, et al. “Differential Branching Fraction and Angular Analysis of Λ[0 over b] → Λμ[superscript +] μ[superscript −] Decays.” J. High Energ. Phys. 2015, no. 6 (June 2015). © CERN, for the benefit of the LHCb Collaboration
Version
Final published version
Abstract
The differential branching fraction of the rare decay Λ[0 over b] → Λμ[superscript +] μ[superscript −] is measured as a function of q [superscript 2], the square of the dimuon invariant mass. The analysis is performed using proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb[superscript −1], collected by the LHCb experiment. Evidence of signal is observed in the q [superscript 2] region below the square of the J/ψ mass. Integrating over 15 < q [superscript 2] < 20 GeV[superscript 2] /c [superscript 4] the differential branching fraction is measured as
dB(Λ[0 over b] → Λμ[superscript +]μ[superscript −])/dq[superscript 2] = (1.18[+0.09 over −0.08] ± 0.03 ± 0.27) × 10[superscript −7] (GeV[superscript 2]/c[superscript 4])[superscript −1],
where the uncertainties are statistical, systematic and due to the normalisation mode, Λ[0 over b] → J/ψΛ, respectively. In the q [superscript 2] intervals where the signal is observed, angular distributions are studied and the forward-backward asymmetries in the dimuon (A[ℓ over FB]) and hadron (A[h over FB]) systems are measured for the first time. In the range 15 < q [superscript 2] < 20 GeV[superscript 2] /c [superscript 4] they are found to be
A[ℓ over FB] = −0.05 ± 0.09(stat) ± 0.03(syst) and A[h over FB] = −0.29 ± 0.07(stat) ±0.03(syst).
MIT Department
Massachusetts Institute of Technology. Department of Physics
Massachusetts Institute of Technology. Laboratory for Nuclear Science
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DOI of Published Version
https://doi.org/10.1007/jhep06(2015)115
