Differential branching fraction and angular analysis of Λ[0 over b] → Λμ[superscript +] μ[superscript −] decays
Author(s)Counts, Ian Thomas Hunt; Ilten, Philip James; Williams, Michael
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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).
DepartmentMassachusetts Institute of Technology. Department of Physics; Massachusetts Institute of Technology. Laboratory for Nuclear Science
Journal of High Energy Physics
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
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