New physics solutions for RD and RD∗

Abstract

Recent measurements of R D∗ have reduced tension with the Standard Model prediction. Taking all the present data into account, we obtain the values of the Wilson coefficients of each new physics four-fermion operator of a given Lorentz structure. We find that the combined data rule out most of the solutions based on scalar/pseudoscalar operators. By studying the inter-relations between different solutions, we find that there are only four allowed solutions, which are based on operators with (V − A), linear combination of (V − A) and (V + A), tensor and linear combination of scalar/pseudoscalar and tensor structure. We demonstrate that the need for new physics is driven by those measurement of R D and R D∗ where the τ lepton is not studied. Further, we show that new physics only in $$ b\to c\ \mu \overline{\nu} $$ b → c μ ν ¯ is not compatible with the full set of observables in the decays $$ B\to Dl\overline{\nu} $$ B → D l ν ¯ and $$ B\to {D}^{\ast }l\overline{\nu} $$ B → D ∗ l ν ¯ .

On lepton flavour universality in semileptonic Bc → ηc, J/ψ decays

“…The constraints on contributions of these NP operators and the corresponding Wilson coefficients are obtained from the experimental results of R D , R D * , polarizations of τ and D * in B → D ( * ) lν decays, as well as on the B c lifetime. There are various studies [43][44][45][46][47][48] performing a global fit on these NP operators considering the presence of only one or two NP operators simultaneously. We have taken the latest constraints on the Wilson coefficients from ref.…”

$$ {R}_{D^{\left(*\right)}},{R}_{K^{\left(*\right)}} $$ and neutrino mass in the 2HDM-III with right-handed neutrinos

“…The latest world-averaged results compiled by the Heavy Flavor Averaging Group (HFLAV) [12] read: R D * = 0.306 ± 0.013(stat) ± 0.007(syst) and R D = 0.407 ± 0.039(stat) ± 0.024(syst), which indicate a combined deviation from the SM values R SM D * ≈ 0.26 [13][14][15][16] and R SM D ≈ 0.30 [14,[16][17][18][19] at the level of 4σ. Thus far, feasible NP scenarios based on model-independent analyses [13,[20][21][22][23][24][25][26][27][28][29][30][31][32] as well as model-dependent constructions such as leptoquarks [33][34][35][36][37][38][39][40][41][42] and two-Higgs-doublet models (2HDM) [35,[43][44][45][46] JHEP09(2018)149 have been extensively studied towards an explanation of the R D ( * ) anomalies. In particular, the general 2HDM of type-III (2HDM-III) with tree-level flavor-changing neutral current (FCNC) can address the R D ( * ) anomalies [44][45][46], but suffers severe constraint from the B − c lifetime [38,…”

Constraining the minimal flavor violating leptoquark explanation of the RD(*) anomaly

“…[9,17,18] considered the interpretation of the data in terms of the type-II two-Higgs doublet model (2HDM) and found it to be inconsistent with the data. On the other hand, besides a plethora of model-independent analysis of the present anomaly [19][20][21][22][23][24][25][26][27][28][29][30][31], one can find in the literature potential explanations in terms of W vector bosons [32][33][34], composite states [35,36], and Frogatt-Nielson-type models [37]. Alternatively, a number of authors have considered leptoquarks as a potential source for the anomaly [38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54].…”