Constraining New Physics with D meson decays

Abstract

Latest Lattice results on $D$ form factors evaluation from first principles show that the standard model (SM) branching ratios prediction for the leptonic $D_s \to \ell \nu_\ell$ decays and the semileptonic SM branching ratios of the $D^0$ and $D^+$ meson decays are in good agreement with the world average experimental measurements. It is possible to disprove New Physics hypothesis or find bounds over several models beyond the SM. Using the observed leptonic and semileptonic branching ratios for the D meson decays, we performed a combined analysis to constrain non standard interactions which mediate the $c\bar{s}\to l\bar{\nu}$ transition. This is done either by a model independent way through the corresponding Wilson coefficients or in a model dependent way by finding the respective bounds over the relevant parameters for some models beyond the standard model. In particular, we obtain bounds for the Two Higgs Doublet Model Type-II and Type III, the Left-Right model, the Minimal Supersymmetric Standard Model with explicit R-Parity violation and Leptoquarks. Finally, we estimate the transverse polarization of the lepton in the $D^0$ decay and we found it can be as high as $P_T=0.23$.Comment: 28 pages, 8 figures, 3 tables. Improved and extended analysis with updated form factors from Lattice QC

Measurements of branching fractions of leptonic and hadronic $ D_s^{+} $ meson decays and extraction of the $ D_s^{+} $ meson decay constant

“…In some NP scenarios, the leptonic decay rates of the D + s mesons could also be modified although the expected effects are smaller than in the B meson sector [6][7][8][9]. Measurements of leptonic decays of charmed hadrons, D + s → + ν where + = e + , µ + or τ + , therefore enable precision tests of LQCD calculations of decay constants performed in the charm sector and can provide additional constraints on NP.…”

“…±4.1 ±2.9 ±3.9 ±5.4 ±3.8 but with a considerable amount of convolution. 8 We obtain the N ch + N π 0 distribution from the N reco ch + N reco π 0 distribution using the singular value decomposition algorithm [41]. Finally, we estimate the ratio between the inclusive D + s reconstruction efficiencies in the data and MC samples, ε inc Ds | DATA /ε inc Ds | MC = 0.9768 ± 0.0134, using the unfolded data and MC N ch + N π 0 distributions and the MC-determined dependence of the inclusive D + s reconstruction efficiency on N ch + N π 0 .…”

Interplay between neutrino magnetic moments andCPviolating phases in left-right models

“…Keeping this in mind, it can be appreciated, from the general structure of Eq. (38), that the assumption of CP invariance yields a cancellation of the magnetic dipole form factor. Moreover, we have verified that CP -conservation consistently yields an analogous elimination of contributions to charge form factors, but electric dipole and anapole form factors perdure.…”

“…From the factors multiplying parametric integrals in Eq. (38), it is explicit that diagonal magnetic dipole form factors, for which β = α, vanish. A cancellation of diagonal electric dipole form factors also happens, but it cannot be determined simply from the general structure of Eq.…”

B ¯ → D ∗ τ ν ¯ $$ \overline{B}\to {D}^{\left(\ast \right)}\tau \overline{\nu} $$ excesses in ALRSM constrained from B, D decays and D 0 − D ¯ 0 $$ {D}^0-{\overline{D}}^0 $$ mixing

“…For τ , this suppression is less severe but phase-space suppression is larger compared to light leptons. In the presence of scalar leptoquark contribution, the SM decay rate is affected in the following way [71,73] …”