14151824
Different kind of textures of Yukawa coupling matrices in the two Higgs doublet model type III
The quark mass matrices ansätze proposed by Fritzsch, Du–Xing and Fukuyama–Nishiura in the framework of the general two Higgs doublet model are studied. The corresponding Yukawa matrices in the flavor basis in the various cases considered are discussed. The corresponding Cabibbo–Kobayashi–Maskawa matrix elements are computed in all cases and compared with their experimental values. The complex phases of the ansätze are taken into account, and the CP violating phase δ is computed. Finally, in order to observe the influence of the various kinds of texture of the Yukawa coupling matrices considered, some issues in the phenomenology of the two body decays of the top quark, the lightest Higgs boson and the charged Higgs boson are discussed.
15573535
NEW PHYSICS EFFECTS IN THE FLAVOR-CHANGING NEUTRAL COUPLINGS OF THE TOP QUARK
We survey the flavor-changing neutral couplings (FCNC) of the top quark predicted by some extensions of the Standard Model: THDM, SUSY, Left–Right symmetric, TC2, 331, and models with extra quarks. Since the expected sensitivity of the LHC and ILC for the tcV (V = γ, g, Z) and tcH couplings is of order of a few percent, we emphasize the importance of any new physics effect that gives a prediction for these FCNC couplings within this limit. We also review the constraints imposed on these couplings from low-energy precision measurements.
117937444
Textures of Yukawa coupling matrices in the 2HDM type III
The quark mass matrices ansatze proposed by Fritzsch, Du‐Xing and Fukuyama‐Nishiura in the framework of the general two Higgs doublet model are studied. The corresponding Cabbibo‐Kobayashi‐Maskawa matrix elements are computed in all cases and compared with their experimental values. The complex phases of the anstaze are taken into account and the CP violating phase δ is computed. Finally some phenomenology is discussed.
124002542
Quark masses and mixing in $SU\left(3\right)_{C}\otimes SU\left(3\right)_{L}\otimes U\left(1\right)_{X}\otimes S_{3}$ models
By imposing a specific $S_{3}$ discrete symmetry for fermions and scalars, we extend the group of the model based on the gauge symmetry $SU(3)_{C}\otimes SU(3)_{L}\otimes U(1)_{X}$. We found that after the symmetry breaking of the continuous group, all the down type quarks acquire tree level masses, while in the up sector only the top quark and a new heavy T quark obtain masses at tree level. By imposing hierarchical Yukawa couplings between the ordinary down-type quarks and new heavy down-type quarks, we may explain the relation $m_{d}<<m_{s}<<m_{b}$. The massless up-type quarks get small mass terms through effective six dimensional operators according to the gauge and discrete symmetries. In particular, the smallness of the u quark can be understood by a small deviation in the universality of the dimensionless couplings associated to the effective operators. We also obtain with only four free parameters, the magnitudes of the CKM matrix elements and the Jarlskog invariant, within experimental error values.
18818705
Heavy quark signals from radiative corrections to the Z-prime boson decay in 3-3-1 models
One-loop corrections to the ${Z}^{\ensuremath{'}}$ decay width are derived and analyzed in the framework of the general form of the 3-3-1 models. We identify two important sources of corrections: oblique corrections associated to the ${Z}^{\ensuremath{'}}$ propagator through vacuum polarizations induced by virtual particle-antiparticle pairs of new heavy quarks $J$, and vertex corrections to the ${Z}^{\ensuremath{'}}q\overline{q}$ vertex through virtual exchange of new ${K}^{{Q}_{1,2}}$ gauge bosons. Fixing a specific renormalization scheme, we obtain dominant oblique corrections that exhibit a quadratic dependence on the $J$ quark mass, which are absorbed into two oblique parameters: a global parameter ${\ensuremath{\rho}}_{f}^{\ensuremath{'}}$ which modify the ${Z}^{\ensuremath{'}}$ decay width, and a parameter ${\ensuremath{\kappa}}_{f}^{\ensuremath{'}}$ that define effective ${Z}^{\ensuremath{'}}$ couplings. Numerical results in an specific 3-3-1 model gives a strong contribution of the oblique corrections from about 1.3% in the $d(s)$ quark channel to 10.5% in the neutrino channel, for ${m}_{J}=2\text{ }\text{ }\mathrm{TeV}$. The vertex corrections contribute to the oblique corrections up to 1.4% for the same channel and ${m}_{J}$ value. For $pp$ collisions at the CERN LHC collider, we find that the corrections significantly modify the shape of the cross section distributions for ${e}^{+}{e}^{\ensuremath{-}}$ and $t\overline{t}$ final states, where the distributions including the radiative corrections increases up to 1.23 times the tree-level distribution for the dielectron events and to 1.07 for the top events when ${m}_{J}=3\text{ }\text{ }\mathrm{TeV}$.
119520979
Bounds for lepton flavor violation and the pseudoscalar Higgs boson in the general two Higgs doublet model using the $g-2$ muon factor
Current experimental data from the $g-2$ muon factor, seems to show the necessity of physics beyond the Standard Model (SM), since the difference between SM and experimental predictions is 2.6$\sigma $. In the framework of the General Two Higgs Doublet Model (2HDM), we calculate the muon anomalous magnetic moment to get lower and upper bounds for the Flavour Changing (FC) Yukawa couplings in the leptonic sector. We also obtain lower bounds for the mass of the pseudoscalar Higgs ($m_{A^0}$) as a function of the parameters of the model.
119563879
Loop-induced radiative decays of neutral scalars and neutral vector bosons in left-right symmetric theories
Abstract We compute the decay widths of the radiative modes h 0 (H 0 , δ L 0r ) → γγ , γ Z and Z′→ γ h 0 (H 0 , δ L 0r ), where h 0 , H 0 and δ L 0r are the light neutral Higgs scalars of left-right symmetric (LR) models with a minimal Higgs potential. We use a nonlinear R -gauge to compute these one-loop induced decays. We find that only the decay modes which involve the scalar h 0 , the LR analogue of the standard model Higgs boson, are not suppressed by LR mixing angles.