848 research outputs found
Phenomenological discriminations of the Yukawa interactions in two-Higgs doublet models with symmetry
There are four types of two-Higgs doublet models under a discrete
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 mixing, , and
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 of and the
ratio could be sensitive probe to discriminate the four models with
future precise measurements of the observables in the
decay at LHCb.Comment: 29 pages, 4 tables, 11 figures. v3: minor corrections included,
matches published version in EPJ
Correlating the CDF -mass shift with the muon and the transitions
Motivated by the latest CDF -mass measurement as well as the muon
anomaly and the discrepancies observed in transitions,
we propose an extension of the Standard Model (SM) with the -singlet
vector-like fermion partners that are featured by additional
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 symmetry breaking. As a result, desirable
loop-level corrections to the , the -boson mass and the
Wilson coefficient in transitions can be obtained.
The final allowed parameter space is also consistent with the constraints from
the 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
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
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 decay in the (dark) SMEFT with minimal flavour violation
Recently, the Belle II collaboration announced the first measurement of
, which is found to be about
higher than the SM prediction. We decipher the data with two new physics
scenarios: the underlying 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 . 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
inv and inv decays. In the MFV hypothesis, the number
of viable operators is reduced to 14, and the inv and
inv decays start to put further constraints. Within the parameter
space allowed by all the current experimental data, the distributions
(and ) of the inv decays are studied for each viable
operator. In addition, we, for the first time, calculate systematically the
longitudinal polarization fraction of in the inv decays
within the DLEFT.Comment: 51 pages, 13 figures, comments welcome; v2: discussions on of
the decay in the DSMEFT added, errors in the 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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