Testing lepton flavour universality in semileptonic $\Lambda_b \to \Lambda_c^*$ decays
| Autor: | Böer, Philipp, Bordone, Marzia, Graverini, Elena, Owen, Patrick, Rotondo, Marcello, van Dyk, Danny |
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| Rok vydání: | 2018 |
| Předmět: | |
| Zdroj: | JHEP 1806 (2018) 155 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1007/JHEP06(2018)155 |
| Popis: | Lepton Flavour Universality tests with semileptonic $\Lambda_b\to\Lambda_c^*$ decays are important to corroborate the present anomalies in the similar ratios $R_{D^{(*)}}$, and can provide complementary constraints on possible origins of these anomalies beyond the Standard Model. In this paper we provide - for the first time - all the necessary theoretical ingredients to perform and interpret measurements of $R_{\Lambda_c^*}$ at the LHCb experiment. For this, we revisit the heavy-quark expansion of the relevant hadronic matrix elements, and provide their expressions to order $\alpha_s$ and $1/m$ accuracy. Moreover, we study the sensitivity to the form factor parameters given the projected size and purity of upcoming and future LHCb datasets of $\Lambda_b\to \Lambda_c^*\mu\bar{\nu}$ decays. We demonstrate explicitly the need to perform a simultaneous fit to both $\Lambda_c^*$ final states. Finally, we provide projections for the uncertainty of $R_{\Lambda_c^*}$ based on the form factor analysis from semimuonic decays and theoretical relations based on the heavy-quark expansion. Comment: 27 pages, 6 figures. v2: Fixed error in subleading IW function, added supplementary information; conclusions unchanged |
| Databáze: | arXiv |
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