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The study of $$ \overline{B}\to {D}^{\ast}\tau {\overline{\nu}}_{\tau } $$angular distribution can be used to obtain information about new physics (or beyond the Standard Model) couplings, which are motivated by various B anomalies. However, the inability to measure precisely the three-momentum of the lepton hinders such measurements, as the tau decay contains one or more undetected neutrinos. Here, we present a measurable angular distribution of $$ \overline{B}\to {D}^{\ast}\tau {\overline{\nu}}_{\tau } $$ by considering the additional decay $$ \tau \to \ell {\nu}_{\tau }{\overline{\nu}}_{\ell } $$, wℓ. The full process used is$$ \overline{B}\to {D}^{\ast}\left(\to D\pi \right)\tau \left(\to \ell {\nu}_{\tau }{\overline{\nu}}_{\ell}\right){\overline{\nu}}_{\tau } $$ $\overline{B}\to D^{\ast }\left(\to \mathrm{D\pi }\right)\tau \left(\to \ell {\nu }_{\tau }{\overline{\nu }}_{\ell }\right){\overline{\nu }}_{\tau }$, in which only theℓandD^*are reconstructed. A fit to the experimental angular distribution of this process can be used to extract information on new physics parameters. To demonstrate the feasibility of this approach, we generate simulated data for this process and perform a sensitivity study to obtain the expected statistical errors on new physics parameters from experiments in the near future. We obtain a sensitivity of the order of 5% for the right-handed current and around 6% for the tensor current. In addition, we use the recent lattice QCD data onB→D^*form factors and obtain correlations between form factors and new physics parameters. 

Flavor physics offers many opportunities to probe the fundamental nature of matter and their interactions. The standard model (SM) of particle physics has a very unique flavor structure which is being tested by precision measurements at flavor experiments. Deviations from the SM predictions can point to new flavor structures and new states which can offer clues to the various flavor puzzles in the standard model. Motivated by recent results and flavor anomalies, we will focus on various processes that can reveal possible extension of the SM with new states such as leptoquarks, diquarks, sterile neutrino and dark sectors. 

Two categories of four-fermion SMEFT operators are semileptonic (two quarks and two leptons) and hadronic (four quarks). At tree level, an operator of a given category contributes only to processes of the same category. However, when the SMEFT Hamiltonian is evolved down from the new-physics scale to low energies using the renormalization-group equations (RGEs), due to operator mixing this same SMEFT operator can generate operators of the other category at one loop. Thus, to search for a SMEFT explanation of a low-energy anomaly, or combination of anomalies, one must: (i) identify the candidate semileptonic and hadronic SMEFT operators, (ii) run them down to low energy with the RGEs, (iii) generate the required low-energy operators with the correct Wilson coefficients, and (iv) check that all other constraints are satisfied. In this paper, we illustrate this method by finding all SMEFT operators that, by themselves, provide a combined explanation of the (semileptonic)$$ \overline{b}\to \overline{s}{\ell}^{+}{\ell}^{-} $$ $\overline{b}\to \overline{s}{\ell }^{+}{\ell }^{-}$anomalies and the (hadronic)B → πKpuzzle. 

In this work, we explore the effect of neutrino nonstandard interactions (NSI) involving the charm quark at SND@LHC. Using an effective description of new physics in terms of four-fermion operators involving a charm quark, we constrain the Wilson coefficients of the effective interaction from two and three-body charmed meson decays. In our fit, we include charmed meson decays not only to pseudoscalar final states but also to vector final states and include decays to the η and η′ final states. We also consider constraints from charmed baryon decays. We then study the effect of new physics in neutrino scattering processes, involving charm production at SND@LHC, for various benchmark new physics couplings obtained from the low energy fits. Finally, we also study the effects of lepton universality violation (LUV) assuming that the new physics coupling is not lepton universal. 

Flavor physics continues to be an interesting avenue to look for beyond the standard model (SM) physics. Recent results from flavor physics, both in the quark and lepton sectors, hint at possible new physics. In this work we focus on some flavor physics results, mainly in b decays, and speculate on possible new physics interpretations of these results. We also present a model that can connect some of the B anomalies to the MiniBooNe anomaly and the muon g − 2 measurement. 

Belle II has reported the first evidence for B+→K+νν¯ with a branching ratio 2.7σ higher than the standard model expectation. We explain this, and the MiniBooNE and muon anomalous magnetic moment anomalies in a model with a dark scalar that couples to a slightly heavier sterile Dirac neutrino and that communicates with the visible sector via a Higgs portal. We make predictions for rare kaon and other B meson decays.