Simultaneous explanation of the RK and R(D(⁎)) puzzles

By Bhubanjyoti Bhattacharya, A. Datta, D. London, Shanmuka Shivashankara. 2014

301 citations recorded by the source corpus.

Abstract At present, there are several hints of lepton flavor non-universality. The LHCb Collaboration has measured R K ≡ B ( B + → K + μ + μ − ) / B ( B + → K + e + e − ) , and the BaBar Collaboration has measured R ( D ( ⁎ ) ) ≡ B ( B ¯ → D ( ⁎ ) + τ − ν ¯ τ ) / B ( B ¯ → D ( ⁎ ) + l − ν ¯ l ) ( l = e , μ ). In all cases, the experimental results differ from the standard model predictions by 2 – 3 σ . Recently, an explanation of the R K puzzle was proposed in which new physics (NP) generates a neutral-current operator involving only third-generation particles. Now, assuming the scale of NP is much larger than the weak scale, this NP operator must be made invariant under the full SU ( 3 ) C × SU ( 2 ) L × U ( 1 ) Y gauge group. In this Letter, we note that, when this is done, a new charged-current operator can appear, and this can explain the R ( D ( ⁎ ) ) puzzle. A more precise measurement of the double ratio R ( D ) / R ( D ⁎ ) can rule out this model.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/953875c8b94e340910ed3e39c80bfb54c72820d9

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Citations in the corpus

Review of lepton universality tests in B decays (2018, background): “In many analyses, only one generation (in the interaction eigenbasis) is assumed to have non-vanishing NP couplings so that LU is violated through the misalignment between the interaction and mass bases [175–177].”
Lepton universality violation with lepton flavor conservation in B-meson decays (2015, background): “The appearance of all the aforementioned anomalies has prompted intense theoretical activity (see for example [5, 7, 21, 22, 24–42]).”
On the breaking of lepton flavor universality in B decays (2015, background): “[21] that is natural to establish a connection between R μ/e K and R τ/` D∗ if the effective four-fermion semi-leptonic operators are build in terms of left-handed doublets.”
Charged Lepton Flavour Violation: An Experimental and Theoretical Introduction (2017, background): “Interestingly, the second operator also gives rise to charged-current interactions, hence it can in principle contribute to the classII observables, RD(∗) , as well [220].”