Status of the semileptonic B decays and muon g-2 in general 2HDMs with right-handed neutrinos

Abstract

In this paper, we study the extended Standard Model (SM) with an extra Higgs doublet and right-handed neutrinos. If the symmetry to distinguish the two Higgs doublets is not assigned, flavor changing neutral currents (FCNCs) involving the scalars are predicted even at the tree level. We investigate the constraints on the FCNCs at the one-loop level, and especially study the semileptonic B meson decays, e.g. B → D ( * ) τ ν and B → K ( * ) ll processes, where the SM predictions are more than 2σ away from the experimental results. We also consider the flavor-violating couplings involving right-handed neutrinos and discuss if the parameters to explain the excesses of the semileptonic B decays can resolve the discrepancy in the anomalous muon magnetic moment. Based on the analysis, we propose the smoking-gun signals of our model at the LHC. arXiv:1802.01732v2 [hep-ph] 1 Jun 2018The Standard Model (SM) succeeds in describing almost all of the experimental results. There is one Higgs doublet to break the electroweak (EW) symmetry, and the nonvanishing vacuum expectation value (VEV) of the Higgs field generates the masses of the gauge bosons and the fermions. We do not still understand the reasons why the EW scale is around a few hundred GeV and why the couplings between the Higgs field and the fermions are so hierarchical. The Higgs particle is, however, discovered at the LHC experiment, and the signal is consistent with the SM prediction [1,2]. Thus, we are certain that the SM describes our nature up to the EW scale.On the other hand, it would be true that the structure of the SM is so mysterious. In addition to the mystery of the origin of the Higgs potential and couplings, the structure of the gauge symmetry is also very non-trivial. The anomaly-free conditions are miraculously satisfied: it is not easy to add extra chiral fermions to the SM. In the bottom-up approach to the new physics, one possible extension is to add extra scalars, e.g. extra Higgs doublets, to avoid the inconsistency with the anomaly-free conditions. Such a simple extension opens up rich phenomenology, so that a simple extended SM with an extra Higgs doublet has been actually discussed since about 40 years ago [3][4][5][6][7][8][9][10].The extended SM, besides, has other interesting aspects, from the viewpoint of the top-down approach. If we consider the new physics that can solve the mysteries of the SM, we often find extra Higgs doublets. For instance, the supersymmetric extension predicts at least one more Higgs doublet. If we consider the extended gauge symmetry, such as SU (2) R , we find extra Higgs doublets that couple to the SM fermions in the effective lagrangian. If we assume that there are flavor symmetries at high energy, there would be many Higgs doublets that couple to the SM fermions flavor-dependently. Thus, it would be very interesting and important to study and summarize the predictions and the experimental constraints of the extended SM with extra Higgs doublets.Based on this background, we investigate not only the experimenta...

Muon g−2 in a U(1) -symmetric two-Higgs-doublet model

“…(µ H ) in our scenario can be obtained by adjusting the relevant Yukawa couplings in Ref [77],. which is also consistent with the ones used in Refs [29,78,85]…”

“…Here we assume that the U (1) symmetry in the quark sector is only an approximate one and allow it to be broken by an additional term in the up-quark sector, treating the coupling Y u 1 as perturbation [49] under the following U (1)-charge assignment: L(Q Li ) = 0, L(d Ri ) = 1, L(u Ri ) = −1, L(Φ 1 ) = 0 and L(Φ 2 ) = −1. Note that we do not include any perturbation in the down-quark sector, as it confronts more severe constraints from flavor physics and collider experiments [29,49,77,78]. As a consequence, the scalarfermion interaction Lagrangian in our scenario is specified as…”

“…The Yukawa texture in Eq. (7) was studied in the general 2HDM, namely the type-III 2HDM, with or without the Cheng-Sher ansatz [29,34,49,77,78,[82][83][84][85][86]. It has been pointed out that a nonzero tc can improve the discrepancy observed in R D ( * ) [34,49,84], while O(1) tt is required to explain the R K ( * ) anomaly [34].…”

Common explanation to the RK(*) , RDMarzo1, Marzola2, Raidal3 2019Phys. Rev. D221110View full textAdd to dashboardCite

“…In recent years, B factories and the LHCb experiment have reported several anomalies [1][2][3][4][5][6][7][8][9][10][11] that find no satisfying explanation in the flavour structure and interactions supported by the standard model (SM) [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. The interpretation of these signals in term of new physics faces, as well, several difficulties, in particular the simultaneous explanation of the R K ( * ) and R D ( * ) measurements proves undoubtedly challenging for the implications on further precision observables that rule out the underlying proposals [30][31][32][33][34][35][36][37].…”

Detecting a μτ -philic Z′ boson via photon initiated processes at the LHC

“…2 The introduction of a new particle with lepton flavor violating µτ couplings is known to be able to explain the observed value of δa µ . Examples of such models are the axion like particle model [9,10], general two Higgs doublet model [11,12,13,14,15,16,17,18] and Z models [19,20,21,22]. In this paper, we consider a vector boson (Z ) which has sizable µτ flavor violating couplings.…”