Indirect bounds on heavy scalar masses of the two-Higgs-doublet model in light of recent Higgs boson searches

We study an upper bound on masses of additional scalar bosons from the electroweak precision data and theoretical constraints such as perturbative unitarity and vacuum stability in the two-Higgs-doublet model taking account of recent Higgs boson search results. If the mass of the Standard-Model-like Higgs boson is rather heavy and is outside the allowed region by the electroweak precision data, such a discrepancy should be compensated by contributions from the additional scalar bosons. We show the upper bound on masses of the additional scalar bosons to be about 2 (1) TeV for the mass of the Standard-Model-like Higgs boson to be 240 (500) GeV.     

Study of the phase structure of an SU(3) Higgs model at finite temperature

We analyse numerically an SU(3) Higgs model with complete symmetry breaking and radial degree of freedom on asymmetric, periodic lattices. The character of both the Higgs and deconfining transitions is found to depend on the Higgs self-coupling and on a parameter which may simulate the number of flavours. In particular, an increase in the latter leads to the disappearance of the deconfining transition for small Higgs masses.     

Neutrino mass and mixing in the 3-3-1 model and S 3 flavor symmetry with minimal Higgs content

A new S ₃ flavor model based on the SU(3) _C ? SU(3) _L ? U(1) _X gauge symmetry responsible for fermion masses and mixings different from our previous work [14, 17] is constructed. The new feature is a two-dimensional representation of a Higgs anti-sextet under S ₃, which is responsible for neutrino masses and mixings. The neutrinos acquire small masses from only an anti-sextet of SU(3), which is in a doublet under S ₃. If the difference of components of the anti-sextet is regarded as a small perturbation, S ₃ is equivalently broken into identity, the corresponding neutrino mass mixing matrix acquires the most general form, and the model can fit the latest data on neutrino oscillations. This way of symmetry breaking helps us reduce a content in the Higgs sector, to only one anti-sextet instead of two as in our previous work [14]. Our results show that the neutrino masses are naturally small and a small deviation from the tri-bimaximal neutrino mixing form can be realized. The Higgs potential of the model as well as the minimization conditions and gauge boson masses and mixings are also considered.     

Masses and couplings of the lightest Higgs bosons in (M + 1)SSM

We study the upper limits on the mass of the lightest and second lightest CP even Higgs bosons in the (M + 1)SSM, the MSSM extended by a gauge singlet. The dominant two loop contributions to the effective potential are included, which reduce the Higgs masses by GeV. Since the coupling R of the lightest Higgs scalar to gauge bosons can be small, we study in detail the relations between the masses and couplings of both lightest scalars. We present upper bounds on the mass of a ”strongly” coupled Higgs (R < 1/2) as a function of lower experimental limits on the mass of a ”weakly” coupled Higgs (R < 1/2). With the help of these results, the whole parameter space of the model can be covered by Higgs boson searches. Received: 7 September 1999 / Published online: 12 July 2002     

Lepton Flavor Violating Z→lIlJ in SO(3) Gauge Extension of SM

The SO(3) gauge extension of SM, which is proposed to present a successfulexplanation for the observed small masses of neutrino and the nearly tri-bimaximal neutrino mixing, predicted the vector-like SO(3) triplet Majorana neutrinos and SU_L(2) double Higgs bosons. In this work we calculate branching ratios of the charged lepton flavor violating decays l_Il_JV (V=γ,Z) induced by these Majorana neutrinos and Higgs bosons. We find that under the model parameters constrained by experimental bounds on the decays Z→l_Il_J, the branching ratio of decays l_I→l_Jγ can be up to 10^-10, which may be accessible at the future experiments.     

Differential cross sections for Higgs boson production at tevatron collider energies

The transverse momentum Q(T) distribution is computed for inclusive Higgs boson production at sqrt[S]=1.96 TeV. We include all-orders resummation of large logarithms associated with emission of soft gluons at small Q(T). We provide results for Higgs boson and Z* masses from M(Z) to 200 GeV. The relatively hard transverse momentum distribution for Higgs boson production suggests possibilities for improvement of the signal to background ratio.     

Search for Higgs Bosons at LEP2 and Hadron Colliders

The search for the Higgs boson was one of the most relevant issues of the final years of LEP running at high energies. An excess of 3σ beyond the background expectation has been found, consistent with the production of the Higgs boson with a mass near 115 GeV/c². At the upgraded TeVatron and at LHC the search for the Higgs boson will continue. At TeVatron Higgs bosons can be detected with masses up to 180 GeV with an assumed total integrated luminosity of 20 fb^—1. LHC has the potential to discover the Higgs boson in many different decay channels for Higgs masses up to 1 TeV. It will be possible to measure Higgs boson parameters, such as mass, width, and couplings to fermions and bosons. The results from Higgs searches at LEP2 and the possibilities for searches at hadron colliders will be reviewed.     

SU(2) × U(1) breaking by vacuum misalignment

Currently two scenarios exist which explain SU(2) × U(1) breaking: the Higgs mechanism, and standard hypercolor schemes. In this paper, a third scenario called “oblique hypercolor” is proposed. A hyperquark condensate is formed which, although kinematically allowed to point in an SU(2) × U(1) preserving direction, is forced by Yukawa interactions of the hyperquarks to misalign by a small angle, breaking SU(2) × U(1). The low energy spectrum involves normal fermions with correct masses, a partially composite Higgs boson, and physical charged scalars.     

SUSY background to neutral MSSM Higgs boson searches

Within the Minimal Supersymmetric Standard Model (MSSM) the production and decay of superpartners can give rise to backgrounds for Higgs boson searches. Here MSSM background processes to the vector boson fusion channel with the Higgs boson decaying into two tau leptons or two W-bosons are investigated, giving rise to dilepton plus missing transverse momentum signals of the Higgs boson. Starting from a scenario with relatively small masses of the supersymmetric (SUSY) particles, with concomitant large cross section of the background processes, one obtains a first conservative estimate of the background. Light chargino pair production plus two jets, lightest and next-to-lightest neutralino production plus two jets as well as slepton pair production plus two jets are identified as important contributions to the irreducible SUSY background. Light chargino and next-to-lightest neutralino production plus two jets and next-to-lightest neutralino pair production plus two jets give rise to reducible backgrounds, which can be larger than the irreducible ones in some scenarios. The relevant distributions are shown and additional cuts for MSSM background reduction are discussed. Extrapolation to larger squark masses is performed and shows that MSSM backgrounds are quite small for squark masses at the current exclusion limits.     

Verifiable model of neutrino masses from large extra dimensions

We propose a new scenario of neutrino masses with a Higgs triplet (xi(++),xi(+),xi(0)) in a theory of large extra dimensions. Lepton number violation in a distant brane acts as the source of a very small trilinear coupling of xi to the standard Higgs doublet in our brane. Small realistic Majorana neutrino masses are naturally obtained with the fundamental scale M(*) approximately O(1) TeV, foretelling the possible discovery of xi (m(xi) less, similarM(*)) at future colliders. Decays of xi(++) into same-sign dileptons are fixed by the neutrino mass matrix. Observation of &mgr;-e conversion in nuclei is predicted.     

Upper bounds on superpartner masses from upper bounds on the Higgs boson mass

The LHC is putting bounds on the Higgs boson mass. In this Letter we use those bounds to constrain the minimal supersymmetric standard model (MSSM) parameter space using the fact that, in supersymmetry, the Higgs mass is a function of the masses of sparticles, and therefore an upper bound on the Higgs mass translates into an upper bound for the masses for superpartners. We show that, although current bounds do not constrain the MSSM parameter space from above, once the Higgs mass bound improves big regions of this parameter space will be excluded, putting upper bounds on supersymmetry (SUSY) masses. On the other hand, for the case of split-SUSY we show that, for moderate or large tanβ, the present bounds on the Higgs mass imply that the common mass for scalars cannot be greater than 10(11) GeV. We show how these bounds will evolve as LHC continues to improve the limits on the Higgs mass.     

θ_(13) and the Higgs Mass from High Scale Supersymmetry

In the framework in which supersymmetry is used for understanding fermion masses rather than stabilizing the electroweak scale, we elaborate on the phenomenological analysis for the neutrino physics. A relatively large sinθ13 0.13 is naturally obtained. The model further predicts vanishingly small CP violation in neutrino oscillations. While the high scale supersymmetry generically results in a Higgs mass of about 141 GeV, our model reduces this mass to 126 GeV via introducing SU(2)L triplet fields which make the electroweak vacuum metastable (with a safe lifetime) and also contribute to neutrino masses.     

Supersymmetry for Fermion Masses

It is proposed that supersymmetry （SUSY） may be used to understand fermion mass hierarchies. A family symmetry ZSL is introduced, which is the cyclic symmetry among the three generation SU（2） doublets. SUSY breaks at a high energy scale - 10^11 GeV. The electroweak energy scale- 100 GeV is unnaturally small No additional global symmetry, like the R-parlty, is imposed. The Yukawa couplings and R-parity violating couplings all take their natural values, which are О（10^0 -10^-2）. Under the family symmetry, only the third generation charged ferrnions get their masses. This family symmetry is broken in the soft SUSY breaking terms, which result in a hierarchical pattern of the fermion masses. It turns out that for the charged leptons, the r mass is from the Higgs vacuum expectation value （VEV） and the sneutrino VEVs, the muon mass is due to the sneutrino VEVs, and the electron gains its mass due to both ZZL and SUSY hreaking. The large neutrino mixing are produced with neutralinos playing the partial role of right-handed neutrinos. │Ve3│, which is for Ve-Vr mixing, is expected to be about 0.1. For the quarks, the third generation masses are from the Higgs VEVs, the second generation masses are from quantum corrections, and the down quark mass due to the sneutrino VEVs. It explains me/ms, ms/me, md 〉 mu and so on. Other aspects of the model are discussed.     

Higgs sector radiative corrections and s-channel production

Higgs boson mass sum rules of supersymmetric models offer attractive targets for precision tests at future muon colliders. These sum rules involve the gauge boson masses as well as the masses of the Higgs boson states which can be precisely measured in the s-channel production process at a muon collider. These measurements can sensitively probe radiative corrections to the Higgs boson masses as well as test for CP violation and nonminimality of the Higgs sector.     

Probing neutrino and Higgs sectors in $$\text{ SU(2) }_1 \times \text{ SU(2) }_2 \times \text{ U(1) }_Y $$ model with lepton-flavor non-universality

The neutrino and Higgs sectors in the \(\text{ SU(2) }_1 \times \text{ SU(2) }_2 \times \text{ U(1) }_Y \) model with lepton-flavor non-universality are discussed. We show that active neutrinos can get Majorana masses from radiative corrections, after adding only new singly charged Higgs bosons. The mechanism for the generation of neutrino masses is the same as in the Zee models. This also gives a hint to solving the dark matter problem based on similar ways discussed recently in many radiative neutrino mass models with dark matter. Except the active neutrinos, the appearance of singly charged Higgs bosons and dark matter does not affect significantly the physical spectrum of all particles in the original model. We indicate this point by investigating the Higgs sector in both cases before and after singly charged scalars are added into it. Many interesting properties of physical Higgs bosons, which were not shown previously, are explored. In particular, the mass matrices of charged and CP-odd Higgs fields are proportional to the coefficient of triple Higgs coupling \(\mu \). The mass eigenstates and eigenvalues in the CP-even Higgs sector are also presented. All couplings of the SM-like Higgs boson to normal fermions and gauge bosons are different from the SM predictions by a factor \(c_h\), which must satisfy the recent global fit of experimental data, namely \(0.995<|c_h|<1\). We have analyzed a more general diagonalization of gauge boson mass matrices, then we show that the ratio of the tangents of the W–\(W'\) and Z–\(Z'\) mixing angles is exactly the cosine of the Weinberg angle, implying that number of parameters is reduced by 1. Signals of new physics from decays of new heavy fermions and Higgs bosons at LHC and constraints of their masses are also discussed.     

Spontaneous CP violating phase as the CKM matrix phase

We propose that the CP violating phase in the CKM mixing matrix is identical to the CP phases responsible for the spontaneous CP violation in the Higgs potential. A multi-Higgs model with Peccei–Quinn (PQ) symmetry is constructed to realize this idea. The CP violating phase does not vanish when all Higgs masses become large. In general, here are flavor changing neutral current (FCNC) interactions mediated by neutral Higgs bosons at the tree level. However, unlike general multi-Higgs models, the FCNC Yukawa couplings are fixed in terms of the quark masses and CKM mixing angles. Implications for meson–anti-meson mixing, including recent data on D–D̄ mixing, and the electric dipole moment (EDM) of the neutron are studied. We find that the neutral Higgs boson masses can be at the order of one hundred GeV. The neutron EDM can be close to the present experimental upper bound.     

Is the standard model saved asymptotically by conformal symmetry?

Journal of Experimental and Theoretical Physics - It is pointed out that the top-quark and Higgs masses and the Higgs VEV with great accuracy satisfy the relations 4m 2 = 2m 2 = v 2, which are very...     

Symmetry breaking in Landau gauge a comment to a paper by T. Kennedy and C. King

For the non-compact abelian lattice Higgs model in Landau gauge Kennedy and King (Princeton preprint, 1985) showed that the two point function does not decay in the Higgs phase. We generalize their methods to show that for the same range of parameters there are states parametrized by an angle [0, 2) such that and 0$$ " align="middle" border="0"> .     

Effects of topology on the light front

We discuss how to construct theta vacua in the light-front field theories using the 1+1 dimensional Abelian Higgs model as an example. Unlike the non-gauged scalar field, zero modes of the Higgs field are in general dynamical as well as the gauge-field zero mode. While symmetry breaking is discussed in semi-classical treatment of the zero modes, the theta vacua are introduced in the quantum level by use of the large gauge symmetry.     

Charged Higgs Pair Production in a General Two Higgs Doublet Model at e^＋e^- and μ^＋μ^- Linear Colliders

In this paper, charged Higgs pair production through l^＋l^- → H^＋ H^-, where l = e or μ, is studied within the framework of a general Two Higgs Doublet Model （2HDM）. The analysis is relevant to a future e^＋e^- or μ^＋ μ^- collider operating at center of mass energy of √s = 500 GeV. Two different scenarios of small and large a values are studied. Here a is the parameter, which diagonMizes the neutral CP-even Higgs boson mass matrix. Within the Minimal Supersymmetric Standard Model （MSSM）, cross section of this process is almost the same at e＋ e- and #＋#- colliders. It is shown that at e^＋e^- eolliders within a general 2HDM, cross section is not sensitive to the mass of neutral Higgs bosons, however, it can acquire large values up to several picobarn at μ^＋μ^- colliders with the presence of heavy neutral Higgs bosons. A scan over Higgs boson mass parameter space is performed to analyze the effect of large masses of neutral Higgs bosons involved in the s-channel propagator and thus in the total cross section of this process.