848 research outputs found

    Phenomenological discriminations of the Yukawa interactions in two-Higgs doublet models with Z2Z_2 symmetry

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    There are four types of two-Higgs doublet models under a discrete Z2Z_2 symmetry imposed to avoid tree-level flavour-changing neutral current, i.e. type-I, type-II, type-X and type-Y models. We investigate the possibility to discriminate the four models in the light of the flavour physics data, including BsBˉsB_s-\bar B_s mixing, Bs,dμ+μB_{s,d} \to \mu^+ \mu^-, BτνB\to \tau\nu and BˉXsγ\bar B \to X_s \gamma decays, the recent LHC Higgs data, the direct search for charged Higgs at LEP, and the constraints from perturbative unitarity and vacuum stability. After deriving the combined constraints on the Yukawa interaction parameters, we have shown that the correlation between the mass eigenstate rate asymmetry AΔΓA_{\Delta\Gamma} of Bsμ+μB_{s} \to \mu^+ \mu^- and the ratio R=B(Bsμ+μ)exp/B(Bsμ+μ)SMR={\cal B}(B_{s} \to \mu^+ \mu^-)_{exp}/ {\cal B}(B_{s} \to \mu^+ \mu^-)_{SM} could be sensitive probe to discriminate the four models with future precise measurements of the observables in the Bsμ+μB_{s} \to \mu^+ \mu^- decay at LHCb.Comment: 29 pages, 4 tables, 11 figures. v3: minor corrections included, matches published version in EPJ

    Correlating the CDF WW-mass shift with the muon g2g-2 and the bs+b \to s \ell^+ \ell^- transitions

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    Motivated by the latest CDF WW-mass measurement as well as the muon g2g-2 anomaly and the discrepancies observed in bs+b \to s \ell^+ \ell^- transitions, we propose an extension of the Standard Model (SM) with the SU(2)LSU(2)_L-singlet vector-like fermion partners that are featured by additional U(1)U(1)^\prime gauge symmetry. The fermion partners have the same SM quantum numbers as of the right-handed SM fermions, and can therefore mix with the latter after the electroweak and the U(1)U(1)^\prime symmetry breaking. As a result, desirable loop-level corrections to the (g2)μ(g-2)_\mu, the WW-boson mass mWm_W and the Wilson coefficient C9C_9 in bsμ+μb \to s \mu^+ \mu^- transitions can be obtained. The final allowed parameter space is also consistent with the constraints from the Zμ+μZ \to \mu^+ \mu^- decay, the neutrino trident production and the LHC direct searches for the vector-like quarks and leptons.Comment: 34 pages, 15 figures, comments welcom

    3,3′-Dibromo-1,1′-[ethyl­enedioxy­bis(nitrilo­methyl­idyne)]dibenzene

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    In the centrosymmetric title compound, C16H14Br2N2O2, the intra­molecular interplanar distance between the parallel benzene rings is 1.305 (3) Å, while the inter­molecular interplanar distance (between neighbouring mol­ecules) is 3.463 (3) Å, exhibiting obvious strong inter­molecular π–π stacking inter­actions

    Molecular mechanism of fluoroquinolones resistance in Mycoplasma hominis clinical isolates

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    To evaluate the molecular mechanism of fluoroquinolones resistance in Mycoplasma hominis (MH) clinical strains isolated from urogenital specimens. 15 MH clinical isolates with different phenotypes of resistance to fluoroquinolones antibiotics were screened for mutations in the quinolone resistance-determining regions (QRDRs) of DNA gyrase (gyrA and gyrB) and topoisomerase IV (parC and parE) in comparison with the reference strain PG21, which is susceptible to fluoroquinolones antibiotics. 15 MH isolates with three kinds of quinolone resistance phenotypes were obtained. Thirteen out of these quinolone-resistant isolates were found to carry nucleotide substitutions in either gyrA or parC. There were no alterations in gyrB and no mutations were found in the isolates with a phenotype of resistance to Ofloxacin (OFX), intermediate resistant to Levofloxacin (LVX) and Sparfloxacin (SFX), and those susceptible to all three tested antibiotics. The molecular mechanism of fluoroquinolone resistance in clinical isolates of MH was reported in this study. The single amino acid mutation in ParC of MH may relate to the resistance to OFX and LVX and the high-level resistance to fluoroquinolones for MH is likely associated with mutations in both DNA gyrase and the ParC subunit of topoisomerase IV

    Deciphering the Belle II data on BKννˉB\to K \nu \bar\nu decay in the (dark) SMEFT with minimal flavour violation

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    Recently, the Belle II collaboration announced the first measurement of B(B+K+ννˉ)\mathcal B(B^+\to K^+\nu\bar\nu), which is found to be about 2.7σ2.7\sigma higher than the SM prediction. We decipher the data with two new physics scenarios: the underlying bsννˉb\to s \nu\bar\nu transition is, besides the SM contribution, further affected by heavy new mediators that are much heavier than the EW scale, or amended by an additional decay channel with undetected light final states like dark matter or axion-like particles. These two scenarios can be most conveniently analyzed in the SMEFT and the dark SMEFT (DSMEFT) framework, respectively. We consider the flavour structures of the resulting effective operators to be either generic or satisfy the minimal flavour violation (MFV) hypothesis, both for the quark and lepton sectors. In the first scenario, once the MFV is assumed, only one SM-like low-energy effective operator induced by the SMEFT dim-6 operators can account for the Belle II excess, the parameter space of which is, however, excluded by the Belle upper bound on B(B0K0ννˉ)\mathcal B(B^0\to K^{*0}\nu\bar\nu). In the second scenario, it is found that the Belle II excess can be accommodated by 22 of the DSMEFT operators involving one or two scalar, fermionic, or vector dark matters as well as ALPs. These operators also receive dominant constraints from the B0K0+B^0\to K^{*0}+inv and BsB_s\toinv decays. In the MFV hypothesis, the number of viable operators is reduced to 14, and the B+π++B^+\to\pi^+ +inv and K+π++K^+\to\pi^++inv decays start to put further constraints. Within the parameter space allowed by all the current experimental data, the q2q^2 distributions (and FLF_L) of the BK()+B\to K^{(*)}+inv decays are studied for each viable operator. In addition, we, for the first time, calculate systematically the longitudinal polarization fraction FLF_L of KK^* in the BK+B\to K^*+inv decays within the DLEFT.Comment: 51 pages, 13 figures, comments welcome; v2: discussions on FLF_L of the BK+invB \to K^* + \text{inv} decay in the DSMEFT added, errors in the BV+invB \to V + \text{inv} decays for some operators involving two scalar or vector DM fields fixed, the related discussions and figures 2, 6, 7, 11 and 12 corrected, main conclusion unchanged, a few comments and refs adde
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