An Improved Standard Model Prediction Of BR(B -> tau nu) And Its Implications For New Physics
Abstract
The recently measured B -> tau nu branching ratio allows to test the Standard Model by probing virtual effects of new heavy particles, such as a charged Higgs boson. The accuracy of the test is currently limited by the experimental error on BR(B -> tau nu) and by the uncertainty on the parameters fB and |Vub|. The redundancy of the Unitarity Triangle fit allows to reduce the error on these parameters and thus to perform a more precise test of the Standard Model. Using the current experimental inputs, we obtain BR(B -> tau nu)_SM = (0.84 +- 0.11)x10^{-4}, to be compared with BR(B -> tau nu)_exp = (1.73 +- 0.34)x10^{-4}. The Standard Model prediction can be modified by New Physics effects in the decay amplitude as well as in the Unitarity Triangle fit. We discuss how to disentangle the two possible contributions in the case of minimal flavour violation at large tan beta and generic loop-mediated New Physics. We also consider two specific models with minimal flavour violation: the Type-II Two Higgs Doublet Model and the Minimal Supersymmetric Standard Model.
Keywords
Cite
@article{arxiv.0908.3470,
title = {An Improved Standard Model Prediction Of BR(B -> tau nu) And Its Implications For New Physics},
author = {UTfit Collaboration and M. Bona and M. Ciuchini and E. Franco and V. Lubicz and G. Martinelli and F. Parodi and M. Pierini and C. Schiavi and L. Silvestrini and V. Sordini and A. Stocchi and C. Tarantino and V. Vagnoni},
journal= {arXiv preprint arXiv:0908.3470},
year = {2014}
}
Comments
7 pages, 13 figures, 1 table. v2: added references and discussion of B -> D tau nu in the 2HDM. v3: added Bs->mumu in the 2HDM. Final version to appear in PLB