Search results for "Yukawa [coupling]"
showing 10 items of 110 documents
LHC sensitivity to singly charged scalars decaying into electrons and muons
2020
Current LHC searches for nonsupersymmetric singly charged scalars, based on two-Higgs-doublet models, in general, focus the analysis in third-generation fermions in the final state. However, singly charged scalars in alternative extensions of the scalar sector involve Yukawa couplings not proportional to the mass of the fermions. Assuming the scalar decays into electrons and muons, it can manifest cleaner experimental signatures. In this paper, we suggest that a singly charged scalar singlet, with electroweak production, can start to be probed in the near future with dedicated search strategies. Depending on the strength of the Yukawa couplings, two independent scenarios are considered: dir…
Higgs Pair Production as a Signal of Enhanced Yukawa Couplings
2018
We present a non-trivial correlation between the enhancement of the Higgs-fermion couplings and the Higgs pair production cross section in two Higgs doublet models with a flavour symmetry. This symmetry suppresses flavour-changing neutral couplings of the Higgs boson and allows for a partial explanation of the hierarchy in the Yukawa sector. After taking into account the constraints from electroweak precision measurements, Higgs coupling strength measurements, and unitarity and perturbativity bounds, we identify an interesting region of parameter space leading to enhanced Yukawa couplings as well as enhanced di-Higgs gluon fusion production at the LHC reach. This effect is visible in both t…
Flavor Changing Yukawa Coupling in the Standard Model and Muon Polarization in KL-->mumu¯
1986
The muon longitudinal polarization P/sub L/ in K/sub L/..--> mu..mu-bar decay is investigated in the standard model. The induced s-bardH vertex responsible for P/sub L/ turns out to be unexpectedly ''large.'' The measurement of P/sub L/ above approx.10/sup -3/ will, therefore, be a signal of the existence of a rather light Higgs boson (M/sub H/< or approx. =10 GeV). It is also shown that the mechanism of gauge-dependence cancellation between Higgs-boson-exchange and box diagrams works even in the standard model.
Charged-Higgs phenomenology in the aligned two-Higgs-doublet model
2010
The alignment in flavour space of the Yukawa matrices of a general two-Higgs-doublet model results in the absence of tree-level flavour-changing neutral currents. In addition to the usual fermion masses and mixings, the aligned Yukawa structure only contains three complex parameters zeta(f), which are potential new sources of CP violation [1]. For particular values of these three parameters all known specific implementations of the model based on discrete Z(2) symmetries are recovered. One of the most distinctive features of the two-Higgs-doublet model is the presence of a charged scalar H-+/-. In this work, we discuss its main phenomenological consequences in flavour-changing processes at …
Exclusive radiative B-meson decays within the aligned two-Higgs-doublet model
2012
In the aligned two-Higgs-doublet model, the alignment of Yukawa matrices in flavour space guarantees the absence of tree-level flavour-changing neutral currents, while allowing at the same time for new sources of CP violation, implying potentially large effects in many low-energy processes. In this work we study the constraints from exclusive radiative $B\to V\gamma$ decays, where $V$ denotes a light vector meson. The current experimental data on the CP-averaged branching ratios and the direct CP and isospin asymmetries are analyzed. It is found that, while the branching ratios and direct CP asymmetries do not constrain the parameter space much further compared to the inclusive $B\to X_{s,d…
Higgs Couplings and Phenomenology in a Warped Extra Dimension
2014
We present a comprehensive description of the Higgs-boson couplings to Standard Model fermions and bosons in Randall-Sundrum (RS) models with a Higgs sector localized on or near the infra-red brane. The analytic results for all relevant Higgs couplings including the loop-induced couplings to gluons and photons are summarized for both the minimal and the custodial RS model. The RS predictions for all relevant Higgs decays are compared with current LHC data, which already exclude significant portions of the parameter space. We show that the latest measurements are sensitive to KK gluon masses up to $20\, \rm{TeV} \times (y_*/3)$ at $95\%$ confidence level for anarchic 5D Yukawa couplings boun…
Systematic Study of Horizontal Gauge Theories
1995
We analyze all the possible continuous horizontal gauge groups G_H in relation with their possibility to explain m_b<<m_t. We assume that the only effective fermionic degrees of freedom correspond to the known fermions but allow the possibility of adding a right handed neutrino to each family. We assume that the Higgs fields which generate masses for these fermions, trough renormalizable Yukawa couplings, transform as an irreducible representation of SU(3)_c\otimesSU(2)_L\otimesU(1)_Y\otimesG_H. Under these assumptions we find two U(1)_H or U(1)_{H1}\otimesU(1)_{H2} models free of anomalies and able to guarantee that only the top has a renormalizable mass-generating Yukawa coupling.
Three-nucleon calculations for local potentials with the quasiparticle method
1974
The three-nucleon system for energies below the breakup threshold is investigated with the help of the quasiparticle method. Two types of local potentials are used, namely purely attractive Yukawa potentials and the soft-core potentials of Malfliet and Tjon. The results obtained are compared with those of other calculations employing different methods.
Mixing induced CP asymmetries in b → sγ decay and spontaneous CP violation
1998
Abstract We analyze the mixing induced CP asymmetry in the decay b → sγ in the left-right symmetric model with spontaneous CP . This model possesses the useful property that all the CP -violating observables can be expressed in term of a single phase, a ratio of scalar vevs, quark masses and weak mixing angles but not on unconstrained quantities such as Yukawa coupling or additional phases. The calculated CP asymmetry can be much larger than in the Standard Model.
Light Quark Yukawa Couplings and the W ± h Charge Asymmetry
2017
Abstract I review the recent theory progress on possibly measuring the light quark couplings, emphasizing the distinction between direct and indirect measurements. I highlight the importance of the W ± h charge asymmetry measurement as a direct probe of enhanced light quark Yukawa couplings. I propose the W ± h → l ± l ± q q ′ ν ν final state as a promising channel for measuring the charge asymmetry. This clean, same-sign dilepton final state should reach statistical discovery sensitivity in each W ± h charge mode with 300 fb -1 of Large Hadron Collider luminosity, and affords an impressive sub-percent statistical accuracy with the anticipated 3 ab -1 high luminosity upgrade. After accounti…