UPDATED BOUNDS ON HIGGS TRIPLET VACUUM EXPECTATION VALUES AND THE TREE-LEVEL ρ PARAMETER FROM RADIATIVE CORRECTIONS

1991 ◽  
Vol 06 (21) ◽  
pp. 1961-1966 ◽  
Author(s):  
THOMAS G. RIZZO
Keyword(s):  
Parity Violation ◽  
Top Quark ◽  
Input Data ◽  
Vacuum Expectation ◽  
Top Quarks ◽  
Higgs Bosons ◽  
Tree Level ◽  
Radiative Corrections ◽  
Expectation Values ◽  
Upper Limits

We obtain 95% C. L. upper limits on the ratio of triplet to doublet vacuum expectation values in two extended electroweak models from radiative corrections. We use as input data from LEP, the Tevatron, the CERN [Formula: see text] colliders, and various low-energy experiments such as atomic parity-violation and deep inelastic scattering. The analysis includes the incorporation of leading two-loop electroweak contributions to ∆r and ρ arising from heavy top quarks and Higgs bosons, the Consoli–Hollik–Jegerlehner resummation technique, and QCD corrections to the hadronic partial widths of the Z using the new value for the (αs/π)3 coefficient. Our limits are found to be only mildly sensitive to the top quark and Higgs boson masses and somewhat stronger than those obtained previously. Our results are then generalized to bounds on the allowed value of the tree-level ρ parameter.

LIGHT TOP QUARK AND LIGHT CHARGED HIGGS REVISITED

1991 ◽  
Vol 06 (37) ◽  
pp. 3375-3383 ◽  
Author(s):  
ANJAN S. JOSHIPURA ◽  
SAURABH D. RINDANI
Keyword(s):  
Top Quark ◽  
Vacuum Expectation ◽  
Scalar Fields ◽  
Discrete Symmetry ◽  
Higgs Bosons ◽  
Expectation Values ◽  
Flavor Changing ◽  
Wide Range ◽  
Down Quark ◽  
Charged Higgs

A model with two Higgs doublets is presented where a discrete symmetry is imposed so that the flavor-changing neutral currents in the down-quark sector are naturally suppressed and obey a hierarchy determined by the hierarchy of the Kobayashi-Maskawa matrix elements. The fermion couplings to charged-Higgs bosons are different from those in models with natural flavor conservation. As a consequence, it is possible to have a light top quark which evades the Tevatron limit by decaying predominantly into a light charged Higgs with mass M H ≤ mt - mb. The model is also consistent with data on ε and [Formula: see text] mixing for a wide range of M H and the ratio of vacuum expectation values of the scalar fields.

scholarly journals Light charged Higgs boson scenario in 3-Higgs doublet models

2017 ◽  
Vol 32 (23n24) ◽  
pp. 1750145 ◽  
Author(s):  
A. G. Akeroyd ◽  
Stefano Moretti ◽  
Kei Yagyu ◽  
Emine Yildirim
Keyword(s):  
Higgs Boson ◽  
Top Quark ◽  
Vacuum Expectation ◽  
Higgs Doublet ◽  
Charged Higgs Boson ◽  
Higgs Bosons ◽  
Tree Level ◽  
Yukawa Couplings ◽  
Charged Higgs ◽  
Charged Higgs Bosons

The constraints from the measurements of the [Formula: see text] decay rate on the parameter space of 3-Higgs Doublet Models (3HDMs), where all the doublets have nonzero vacuum expectation values, are studied at the next-to-leading order in QCD. In order to naturally avoid the presence of flavour changing neutral currents at the tree level, we impose two softly-broken discrete [Formula: see text] symmetries. This gives rise to five independent types of 3HDMs that differ in their Yukawa couplings. We show that in all these 3HDMs (including the case of type-II-like Yukawa interactions) both masses of the two charged Higgs bosons [Formula: see text] and [Formula: see text] can be smaller than the top mass [Formula: see text] while complying with the constraints from [Formula: see text]. As an interesting phenomenological consequence, the branching ratios of the charged Higgs bosons decay into the [Formula: see text] final states can be as large as [Formula: see text] when their masses are taken to be below [Formula: see text] in two of the five 3HDMs (named as Type-Y and Type-Z). This light charged Higgs boson scenario provides a hallmark 3HDM signature that cannot be realised in [Formula: see text] symmetric 2-Higgs doublet models. We find that in the Type-Y and Type-Z 3HDMs the scenario with [Formula: see text], [Formula: see text] is ruled out by the direct searches at the LHC, but in the Type-Y 3HDM [Formula: see text] and [Formula: see text] is allowed by [Formula: see text] and direct searches at LEP2, Tevatron and LHC due to the reduced sensitivity of these searches to the degenerate case [Formula: see text]. The cases where only one or both charged Higgs bosons are above the top quark mass are also naturally allowed in the both Type-Y and Type-Z 3HDMs.

SEARCH FOR CHARGED HIGGS BOSONS AT SSC

1987 ◽  
Vol 02 (04) ◽  
pp. 1055-1067 ◽  
Author(s):  
Hans-Uno Bengtsson ◽  
Hiroaki Yamamoto ◽  
Sachio Komamiya
Keyword(s):  
Decay Mode ◽  
Top Quark ◽  
Vacuum Expectation ◽  
Higgs Doublet ◽  
Higgs Bosons ◽  
Quark Interaction ◽  
Charged Higgs ◽  
Charged Higgs Bosons ◽  
Two Higgs Doublet Models ◽  
Very High

We examine the possibility of finding charged Higgs bosons (H±) at the SSC. The charged Higgs boson is produced with a top quark via a gluon+bottom quark interaction (g+b→H+t). For the two Higgs doublet models, H± decays predominantly into t+b. Since the background from QCD processes will be very severe for this decay mode, we studied the H±→τ+ν decay mode. Even for this mode, background from the processes pp→W+t+spectators→ℓ+νℓ+t+spectators will be very high. In the two Higgs doublet models, it is very difficult to extract the charged Higgs signal for reasonable values of the ratio of the two vacuum expectation values ( tan β=v1/v2).

SPONTANEOUS CP VIOLATION IN A TWO-GENERATION LEFT-RIGHT SYMMETRIC MODEL WITH TWO HIGGS BI-DOUBLETS

1992 ◽  
Vol 07 (34) ◽  
pp. 3179-3186 ◽  
Author(s):  
AMBAR GHOSAL ◽  
ASIM K. RAY ◽  
SASWATI SARKAR
Keyword(s):  
Cp Violation ◽  
Relative Phase ◽  
Vacuum Expectation ◽  
Discrete Symmetry ◽  
Tree Level ◽  
Model Parameters ◽  
Symmetric Model ◽  
Expectation Values ◽  
Flavor Changing ◽  
Experimental Values

We discuss a two-generation left-right symmetric model with two Higgs bi-doublets and a discrete symmetry to show that spontaneous CP violation arises as a result of soft breaking of the discrete symmetry. The contributions to the CP violation parameter ε in the [Formula: see text] transition come from the box diagrams due to WL-WR exchanges as well as from the mixing of the real and imaginary parts of the flavor changing neutral Higgs at the tree level and both contributions depend on the relative phase difference between the vacuum expectation values (vevs) of the relevant neutral Higgs scalars. Other CP violating effects in the model are consistent with their experimental values for the appropriate choice of the model parameters. The extension of the model to the realistic case of three generations of fermions does not appreciably change the phenomenology of the model.

SEARCH FOR CHARGED HIGGS BOSONS IN DECAYS OF PAIR-PRODUCED TOP QUARKS AT DØ

2001 ◽  
Vol 16 (supp01a) ◽  
pp. 395-398
Author(s):  
◽  
PHILLIP GUTIERREZ
Keyword(s):  
Standard Model ◽  
Top Quark ◽  
Top Quarks ◽  
Higgs Bosons ◽  
Full Data ◽  
The Standard Model ◽  
Charged Higgs ◽  
Charged Higgs Bosons

We present a search for t → bH+ in [Formula: see text] candidate events at DØ based on two methods. The first seeks a deficit in signal relative to expectations from the standard model (SM). Such a deficit would imply the presence of a non-SM decay of the top quark. This search involves the full data sample of ≈ 110 pb -1 of [Formula: see text] collisions at [Formula: see text], collected with the DØ detector. The second method looks for charged Higgs decays to τ leptons (and associated neutrinos), and is based on a 62 pb -1 subset of the aforementioned data sample.

$B^0 - \bar B^0 $ MIXING IN A SUPERSYMMETRY-INSPIRED TWO HIGGS DOUBLET MODEL

1988 ◽  
Vol 03 (11) ◽  
pp. 1099-1105 ◽  
Author(s):  
AMITAVA RAYCHAUDHURI ◽  
SREERUP RAYCHAUDHURI
Keyword(s):  
Top Quark ◽  
Quark Mass ◽  
Higgs Mass ◽  
Vacuum Expectation ◽  
Higgs Doublet ◽  
Top Quark Mass ◽  
Expectation Values ◽  
Charged Higgs ◽  
Doublet Model ◽  
Two Higgs Doublet Model

A supersymmetry-motivated two Higgs doublet model with equal vacuum expectation values for the two neutral Higgs and with a physical charged Higgs mass of 80–100 GeV is carefully examined in the context of its implications for [Formula: see text] mixing. Even with this conservative choice of Higgs parameters, the lower bound on the top quark mass coming from the ARGUS data is found to be considerably relaxed. An upper bound is also set, using results from CLEO and Mark II.

SCALAR TOP PRODUCTION VIA BOSON-GLUON FUSION AT HERA

1992 ◽  
Vol 07 (14) ◽  
pp. 1209-1218 ◽  
Author(s):  
TETSURO KOBAYASHI ◽  
TADASHI KON ◽  
KEIICHIRO NAKAMURA ◽  
TAKESHI SUZUKI
Keyword(s):  
Total Cross Section ◽  
Cross Section ◽  
Top Quark ◽  
Gluon Fusion ◽  
Top Quarks ◽  
Tree Level ◽  
Mixing Angle ◽  
Light Scalar ◽  
Scalar Top ◽  
Level Calculation

We investigate the production of the light scalar top quark [Formula: see text] via boson-gluon fusion at ep collider HERA, based on the minimal supersymmetric standard model. The cross-section is obtained by both an exact tree level calculation and the Weizsäcker-Williams approximation. It is shown that the total cross-section is larger than 0.1pb if [Formula: see text] and does not depend on the mixing angle θt of scalar top quarks. This enables us to search a possible region of parameters for existence of light scalar top at HERA in a wider parameter space [Formula: see text] than LEP.

QUASI SUPERSYMMETRY WITHIN THE STANDARD MODEL AND HIGGS MASS

1999 ◽  
Vol 14 (35) ◽  
pp. 2447-2452
Author(s):  
B. B. DEO ◽  
L. P. SINGH
Keyword(s):  
Standard Model ◽  
Top Quark ◽  
Degrees Of Freedom ◽  
Higgs Mass ◽  
Higgs Bosons ◽  
Tree Level ◽  
Mass Relation ◽  
The Standard Model ◽  
A Charge ◽  
Higgs Fields

The 12 bosonic degrees of freedom of the standard model (SM) are exactly matched by fermionic degrees of freedom of a single colored quark, e.g. top. Indeed, we construct a charge involving top-quark, gauge and Higgs fields which satisfy usual supersymmetry algebra. The colored quark states behave like the superpartners of gauge and Higgs bosons and vice versa. When this SUSY is broken, a mass relation must be satisfied at the tree level from which the mass of the Higgs is predicted to be 300.5±11 GeV.

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