ExplainingB→Dτν,B→D*τνandB→

Status of B to D(*) τ ν decays in two-Higgs-doublet models

“…[13] that none of the 2HDMs with natural flavour conservation (NFC) can simultaneously accommodate the current measurements of the three ratios {R(D), R(D * ), R π τ/ }. To accommodate the experimental data on tauonic-B decays: B → D ( * ) τν and B → τν, one has to allow for a more general Yukawa structure as provided by the Yukawa alignment hypothesis (A2HDM) or by assuming the presence of tree-level FCNCs [14]. The preferred values for the charged Higgs couplings needed to explain R(D * ) and Br(B → τν) within the A2HDM, are however not compatible with current constraints from D (s) -meson leptonic decay rates as shown in Fig.…”

New physics in the kinematic distributions of B¯→D(*)τ−(→

“…The discrepancy between experiment and the SM is at the level of 4σ, and it can be explained with new physics (NP) [11,[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. These analyses of the data are most fruitful when casted model-independently in an effective field theoretical framework.…”

Anomalous enhancement observed inB→D(*)τν¯τdecays

“…As done in [2][3][4][5][6][7]9], R(D) and R(D * ) data allow to constrain the values of the new effective dimensionless coupling. In our case T is bounded as shown in fig.3.…”

“…The measurements have been estimated to deviate at the global level of 3.4σ with respect to SM predictions [1,2]. Therefore, there is the possibility that semileptonic processes involving heavy quarks and the τ lepton are unveiling the effects of particles with large couplings to the heavier fermions, as it is natural for charged scalars which could contribute to the tree-level b → c ν transitions [2][3][4][5][6][7][8][9]. Before the observation of these possible hints of new physics (NP) in semileptonic b → c decays, the first experimental analyses of the purely leptonic B − → τ −ν τ mode also reported an excess of events.…”

“…In this framework, the ratios (1) depend on the mass of the charged Higgs H ± and the ratio β of the two Higgs doublet VEVs, and no choice of such parameters allows to simultaneously reproduce the experimental data on R(D) and R(D * ) [1]. Variants of the 2HDM [4,7], together with other models providing explicit flavour violation [3], might explain the measurements (1); however, an enhancement of the purely leptonic B decay rate is generally implied.…”