arXiv:2401.12304v2 Announce Type: replace-cross Abstract: The Belle Collaboration has recently measured the complete set of angular coefficient functions for the exclusive decays $\bar B \to D^* (D \pi) \ell \bar \nu_\ell$, with $\ell=e,\,\mu$, in four bins of the parameter $w=\displaystyle\frac{m_B^2+m_{D^*}^2-q^2}{2m_B m_{D^*}}$, with $q$ the lepton pair momentum. Under the assumption that physics beyond the Standard Model does not contribute to such modes, the measurements are useful to determine the hadronic form factors describing the $B \to D^*$ matrix elements of the Standard Model weak current, and to improve the determination of $|V_{cb}|$. On the other hand, they can be used to assess the impact of possible new physics contributions. In a bottom-up approach, we extend the Standard Model effective Hamiltonian governing this mode with the inclusion of the full set of Lorentz invariant d=6 operators compatible with the gauge symmetry of the theory. The measured angular coefficient functions can tightly constrain the couplings in the generalized Hamiltonian. We present the first results of this analysis, discussing how improvements can be achieved when more complete data on the angular coefficient functions will be available.

arXiv:2402.13983v5 Announce Type: replace-cross Abstract: 1. I update my previous comparison of the theoretical value of the muon anomaly with the new measurement and found $\Delta a_\mu\equiv a_\mu^{exp}-a_\mu^{th} = (143\pm 42_{th}\pm 22_{exp})\times 10^{-11}$ which is about 3$\sigma$ discrepancy between the SM predictions and experiment. 2. I improve the estimate of QCD power corrections up to dimension D=12 and provide a new estimate of the ones up to D=20 within the SVZ expansion by combining the ratio of the Laplace sum rules (LSR) with the BNP $\tau$-like decay moments for the I=1 vector current. The results in Table 1 confirm a violation of the factorization of the four-quark condensates and the value of the gluon one $ $ from some other sources. Up to D=20, I there is not any factorial nor exponential growth of the size of these power corrections. 3. I use these new values of power corrections to extract $\alpha_s$ from the BNP lowest moment. To order $\alpha_s^4$, I find within the SVZ expansion: $\alpha_s(M_\tau)= 0.3081(50)_{fit}(71)_{\alpha_s^5}$ [resp. $0.3260 (47)_{fit}(62)_{\alpha_s^5}]$ implying $\alpha_s(M_Z)= 0.1170(6)(3)_{evol}$ [resp. $0.1192(6)(3)_{evol}$] for Fixed Order (FO) [resp. Contour Improved (CI)] PT series. They lead to the mean: $ \alpha_s(M_\tau)\vert_{SVZ}=0.3179(58)_{fit}(81)_{syst}$ and $ \alpha_s(M_Z)\vert_{SVZ}= 0.1182(12)(3)_{evol}$ where the systematic error(syst) takes into account the discrepancy between FO and CI. Using the lowest BNP moment, we also obtain from the vector (V) component of $\tau$-decay the mean: $ \alpha_s(M_\tau)\vert_{\tau,V}=0.3219(52)(91)_{syst}$ giving: $\alpha_s(M_Z)\vert_{\tau,V}=0.1187(13)(3)_{evol}$. The average of the two determinations leads to: $ \alpha_s(M_\tau)=0.3198(72)$ and $\alpha_s(M_Z)= 0.1185(9)(3)_{evol}$. 4. Some contributions beyond the SVZ expansion ($1/Q^2$, instantons and duality violation) expected to be small are discussed in Sections 10,11.

arXiv:2402.16851v2 Announce Type: replace-cross Abstract: Interactions of charged leptons with nuclei and the naive tree-level kinematics of these processes are affected by radiation of photons induced by the QED nuclear medium. We evaluate cross-section modifications at leading orders of the number of correlated interactions inside the nucleus, known as the opacity expansion. We derive results for soft and collinear types of the bremsstrahlung at the first three orders in opacity and generalize them to higher orders. We present the leading in opacity energy spectra of soft and collinear photons and radiative energy loss inside the nucleus for experiments with lepton kinematics in the GeV energy range. At leading power of the Glauber soft-collinear effective field theory, the soft radiation is further resummed to all orders both in opacity and in the electromagnetic coupling constant. We find that the soft and collinear medium-induced radiation is vacuumlike, and additional corrections are power suppressed. Despite the negligible modification to the induced photon spectra, the nuclear medium-induced radiation sizably affects the broadening of charged leptons in the direction orthogonal to their propagation.