Differential branching fraction and angular analysis of \(\Lambda^{0}_{b} \rightarrow \Lambda \mu^+\mu^-\) decays

• Published in: arXiv.org
• Main Authors: collaboration, LHCb, Badalov, A, Baesso, C, Battista, V, Bien, A, Brook, N H, Calabrese, R, Carbone, A, Cardinale, R, K Carvalho Akiba, Closier, J, Collazuol, G, Cowan, G A, De Cian, M, De Paula, L, C -T Dean, Dijkstra, H, Dorigo, M, Dujany, G, Dziurda, A, Dzyuba, A, Eitschberger, U, I El Rifai, V Fernandez Albor, F Ferreira Rodrigues, Ferro-Luzzi, M, Fol, P, J Fu, J García Pardiñas, Gersabeck, M, Giubega, L, Golutvin, A, Gregson, S, Hadjivasiliou, C, Hall, S, E van Herwijnen, Hynds, D, Jing, F, Johnson, D, Kandybei, S, Kanso, W, Khurewathanakul, C, Koopman, R F, La Thi, V N, Lazzeroni, C, R Le Gac, Leflat, A, Liles, M, Lopes, J H, Lucchesi, D, Lupato, A, Manca, G, Marino, P, Massafferri, A, Mathad, A, McCann, M, Meier, F, Nandakumar, R, Nasteva, I, Nikitin, N, Ogilvy, S, Otalora Goicochea, J M, Pearce, A, Penso, G, M Plo Casasus, Popov, D, Pritchard, A, Rademacker, J H, Rangel, M S, Raniuk, I, dos Reis, A C, Ricciardi, S, Rinnert, K, A Romero Vidal, Ruiz, H, Satta, A, Saunders, D M, Schiller, M, Shapkin, M, Shcheglov, Y, Sokoloff, M D, Souza, D, Souza De Paula, B, Sterpka, F, Stroili, R, Thomas, E, Tolk, S, Tomassetti, L, Viana Barbosa, J V, M Vieites Diaz, Vilasis-Cardona, X, Vorobyev, V, Watson, N K, Wiedner, D, Wishahi, J, Witek, M, Wormser, G, Wotton, S A, Zavertyaev, M, Zhang, L
• Format: Paper
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 29.05.2015
• Subjects: Large Hadron Collider; Luminosity; Particle collisions
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1503.07138

The differential branching fraction of the rare decay \(\Lambda^{0}_{b} \rightarrow \Lambda \mu^+\mu^-\) is measured as a function of \(q^{2}\), the square of the dimuon invariant mass. The analysis is performed using proton-proton collision data, corresponding to an integrated luminosity of \(3.0 \mbox{ fb}^{-1}\), collected by the LHCb experiment. Evidence of signal is observed in the \(q^2\) region below the square of the \(J/\psi\) mass. Integrating over \(15 < q^{2} < 20 \mbox{ GeV}^2/c^4\) the branching fraction is measured as \(d\mathcal{B}(\Lambda^{0}_{b} \rightarrow \Lambda \mu^+\mu^-)/dq^2 = (1.18 ^{+ 0.09} _{-0.08} \pm 0.03 \pm 0.27) \times 10^{-7} ( \mbox{GeV}^{2}/c^{4})^{-1}\), where the uncertainties are statistical, systematic and due to the normalisation mode, \(\Lambda^{0}_{b} \rightarrow J/\psi \Lambda\), respectively. In the \(q^2\) intervals where the signal is observed, angular distributions are studied and the forward-backward asymmetries in the dimuon (\(A^{l}_{\rm FB}\)) and hadron (\(A^{h}_{\rm FB}\)) systems are measured for the first time. In the range \(15 < q^2 < 20 \mbox{ GeV}^2/c^4\) they are found to be \(A^{l}_{\rm FB} = -0.05 \pm 0.09 \mbox{ (stat)} \pm 0.03 \mbox{ (syst)}\) and \(A^{h}_{\rm FB} = -0.29 \pm 0.07 \mbox{ (stat)} \pm 0.03 \mbox{ (syst)}\).