HIGGS PROPAGATOR IN THE PRESENCE OF STRONG DYNAMICS IN THE ELECTROWEAK SECTOR

2000 ◽  
Vol 15 (24) ◽  
pp. 1483-1490
Author(s):  
BIPIN R. DESAI ◽  
ALEXANDER R. VAUCHER
Keyword(s):  
Yukawa Coupling ◽  
Higgs Mass ◽  
Scattering Amplitude ◽  
Precision Measurements ◽  
The Standard Model ◽  
200 Gev ◽  
Low Mass ◽  
Electroweak Sector ◽  
Top Mass ◽  
Compositeness Scale

The Higgs propagator, in the presence of strong top-Yukawa coupling, is expressed in the form of dispersion integrals so that unitarity in top–antitop scattering amplitude is maintained. It is found that a large top-Yukawa coupling lowers the Higgs mass from the condensate-model value of twice the top mass (≈350 GeV) to 100–200 GeV consistent with the Z0 width precision measurements. The coupling is found to be ≈3.7 at the top-mass, much larger than the Standard Model value ≈1. It corresponds to a compositeness scale ≈1.4 TeV, which is consistent with top-color models. A second scalar state around 1 TeV also emerges as a solution in combination with the low mass Higgs.

scholarly journals A CALCULATION OF HIGGS MASS IN THE STANDARD MODEL

2000 ◽  
Vol 15 (26) ◽  
pp. 1605-1610 ◽  
Author(s):  
J. PASUPATHY
Keyword(s):  
Standard Model ◽  
Yukawa Coupling ◽  
Higgs Mass ◽  
Renormalization Scale ◽  
The Standard Model ◽  
Gauge Couplings ◽  
Top Mass

The assumption that the ratio of the Higgs self-coupling to the square of its Yukawa coupling to the top is (almost) independent of the renormalization scale fixes the Higgs mass within narrow limits at m H =160 GeV using only the values of gauge couplings and top mass.

scholarly journals Exact one-loop running couplings in the standard model

2008 ◽  
Vol 86 (9) ◽  
pp. 1067-1070 ◽  
Author(s):  
F A Chishtie ◽  
M D Lepage ◽  
D GC McKeon ◽  
T G Steele ◽  
I Zakout
Keyword(s):  
Standard Model ◽  
Yukawa Coupling ◽  
Top Quark ◽  
Higgs Mass ◽  
Gauge Coupling ◽  
New Physics ◽  
Energy Scale ◽  
Scalar Coupling ◽  
Upper And Lower Bounds ◽  
The Standard Model

Taking the dominant couplings in the standard model to be the quartic scalar coupling, the Yukawa coupling of the top quark, and the SU(3) gauge coupling, we consider their associated running couplings to one-loop order. Despite the nonlinear nature of the differential equations governing these functions, we show that they can be solved exactly. The nature of these solutions is discussed and their singularity structure is examined. It is shown that for a sufficiently small Higgs mass, the quartic scalar coupling decreases with increasing energy scale and becomes negative, indicative of vacuum instability. This behavior changes for a Higgs mass greater than 168 GeV, beyond which this couplant increases with increasing energy scales and becomes singular prior to the ultraviolet pole of the Yukawa coupling. Upper and lower bounds on the Higgs mass corresponding to new physics at the TeV scale are obtained and compare favourably with the numerical results of the one-loop and two-loop analyses with inclusion of electroweak couplings.PACS Nos.: 11.10.Hi, 14.80.Bn

scholarly journals Probing loop effects in wrong-sign Yukawa coupling region of Type-II 2HDM

2021 ◽  
Vol 81 (5) ◽  
Author(s):  
Wei Su
Keyword(s):  
Parameter Space ◽  
Yukawa Coupling ◽  
Higgs Mass ◽  
Precision Measurements ◽  
Tree Level ◽  
Type Ii ◽  
Coupling Region ◽  
Loop Level ◽  
Wrong Sign

AbstractIn the framework of 2HDM, we explore the wrong-sign Yukawa region with direct and indirect searches up to one-loop level. The direct searches include the latest $$H/A \rightarrow f{\bar{f}}, VV, Vh, hh$$ H / A → f f ¯ , V V , V h , h h reports at current LHC, and the study of indirect Higgs precision measurements works with current LHC, future HL-LHC and CEPC. At tree level of Type-II 2HDM, for degenerate heavy Higgs mass $$m_A=m_H=m_{H^\pm }<800$$ m A = m H = m H ± < 800 GeV, the wrong-sign Yukawa regions are excluded largely except for the tiny allowed region around $$\cos (\beta -\alpha )\in (0.2,0.3)$$ cos ( β - α ) ∈ ( 0.2 , 0.3 ) under the combined Higgs constraints. The excluded region is also nearly independent of parameter $$m_{12}$$ m 12 or $$\lambda v^2=m_A^2-m_{12}^2/(\sin \beta \cos \beta )$$ λ v 2 = m A 2 - m 12 2 / ( sin β cos β ) . The situation changes a lot after including loop corrections to the indirect searches, for example $$m_A=1500 \text {~GeV}$$ m A = 1500 GeV , the region with $$\lambda v^2<0$$ λ v 2 < 0 will be stronger constrained to be totally excluded. Whilst parameter space with $$\lambda v^2>0$$ λ v 2 > 0 would get larger survived wrong-sign region for $$m_A=800 ~\text {~GeV}$$ m A = 800 GeV compared to it at tree level. We also conclude Higgs direct searches works better on constraining $$\lambda v^2 \approx 0$$ λ v 2 ≈ 0 GeV range than theoretical constraints. We also find that the loop-level wrong-sign Yukawa limit only occurs at mass decoupling scale.

scholarly journals THE STANDARD MODEL AND PROTON-ANTIPROTON COLLIDERS IN THE ACOL/TEV I ERA

1988 ◽  
Vol 03 (05) ◽  
pp. 1051-1079 ◽  
Author(s):  
J.R. CUDELL ◽  
F. HALZEN ◽  
C.S. KIM
Keyword(s):  
Large Fraction ◽  
Collider Physics ◽  
Hadron Colliders ◽  
Proton Antiproton ◽  
Electroweak Radiative Corrections ◽  
The Standard Model ◽  
200 Gev ◽  
Indirect Information ◽  
Near Future ◽  
Top Mass

[Formula: see text] collider physicists must in the near future face the question: Is there life after Tristan, SLC, LEP, and HERA? We review the main topics of [Formula: see text] collider physics (jets, weak bosons, and heavy quarks) concentrating on physics issues unique to hadron colliders. We emphasize the search for top. After reviewing indirect information on the top mass (from electroweak radiative corrections, ratio of W(→eν) and Z(→e+e−) events and [Formula: see text] mixing) we discuss the unique opportunity to search a large fraction of the expected range 25 GeV <mt<200 GeV in higher energy (TEV I) and higher luminosity (ACOL) experiments.

scholarly journals PRECISION SUPERSYMMETRY MEASUREMENTS AT THE e-e- COLLIDER

1998 ◽  
Vol 13 (14) ◽  
pp. 2329-2336 ◽  
Author(s):  
HSIN-CHIA CHENG
Keyword(s):  
Standard Model ◽  
High Precision ◽  
Gauge Boson ◽  
Linear Collider ◽  
Direct Detection ◽  
Precision Measurements ◽  
Supersymmetric Particle ◽  
The Standard Model ◽  
Electroweak Sector ◽  
Future Linear Collider

Measurements of supersymmetric particle couplings provide important verification of supersymmetry. If some of the superpartners are at the multi-TeV scale, they will escape direct detection at planned future colliders. However, such particles induce nondecoupling corrections in processes involving the accessible superparticles through violations of the supersymmetric equivalence between gauge boson and gaugino couplings. These violations are analogous to the oblique corrections in the electroweak sector of the Standard Model, and can be parametrized in terms of super-oblique parameters. The e-e- collision mode of a future linear collider is shown to be an excellent environment for such high precision measurements of these SUSY parameters, which will provide an important probe of superparticles beyond reachable energies.

scholarly journals STANDARD MODEL HIGGS SEARCHES AT THE TEVATRON

2012 ◽  
Vol 27 (24) ◽  
pp. 1230023 ◽  
Author(s):  
◽  
WEIMING YAO
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Mass Range ◽  
Standard Model Higgs Boson ◽  
Proton Antiproton ◽  
The Standard Model ◽  
200 Gev ◽  
Low Mass ◽  
Standard Deviations ◽  
Local Significance

We present the results of direct searches for the Standard Model Higgs boson at the Tevatron. Results are derived from the complete Tevatron Run II dataset, with a measured integrated luminosity of 10 fb-1 of proton–antiproton data. The searches are performed for assumed Higgs masses between 90 and 200 GeV /c2. We observe an excess of events in the data compared with the background predictions, which is most significant in the mass range between 115 and 135 GeV /c2, consistent with the Higgs-like particle recently observed by ATLAS and CMS. The largest local significance is 2.7 standard deviations, corresponding to a global significance of 2.2 standard deviations. We also combine separate searches for [Formula: see text] and H→W+W-, and find that the excess is concentrated in the [Formula: see text] channel, although the results in the H→W+W- channel are still consistent with the possible presence of a low-mass Higgs boson.

Z BRANCHING FRACTIONS AND THE TOP MASS

1990 ◽  
Vol 05 (13) ◽  
pp. 1001-1005 ◽  
Author(s):  
R. D. PECCEI
Keyword(s):  
Narrow Range ◽  
Branching Fractions ◽  
Precision Measurements ◽  
Radiative Corrections ◽  
Electroweak Radiative Corrections ◽  
200 Gev ◽  
Top Mass

Recent data from LEP on the hadronic and leptonic branching fractions of the Z0 favors a narrow range for the top mass around 200 GeV. These results are consistent with other precision measurements sensitive to the electroweak radiative corrections.

scholarly journals ELECTROWEAK MEASUREMENTS

2006 ◽  
Vol 21 (08n09) ◽  
pp. 1604-1616 ◽  
Author(s):  
CRISTINEL DIACONU
Keyword(s):  
Standard Model ◽  
W Boson ◽  
Low Energy ◽  
Precision Measurements ◽  
Production Processes ◽  
The Standard Model ◽  
The Status ◽  
Electroweak Sector

The measurements of electroweak sector of the Standard Model are presented, including most recent results from LEP, Tevatron and HERA colliders. The robustness of the Standard Model is illustrated with the precision measurements, the electroweak fits and the comparisons to the results obtained from low energy experiments. The status of the measurements of the W boson properties and rare production processes involving weak bosons at colliders is examined, together with the measurements of the electroweak parameters in ep collisions.

scholarly journals LIGHT COMPOSITE HIGGS: LCH @ LHC

2005 ◽  
Vol 20 (27) ◽  
pp. 6133-6148 ◽  
Author(s):  
FRANCESCO SANNINO
Keyword(s):  
Gauge Group ◽  
Higgs Mass ◽  
Cold Dark Matter ◽  
Precision Measurements ◽  
Chiral Phase ◽  
Symmetric Representation ◽  
Composite Higgs ◽  
Higher Dimensional ◽  
The One ◽  
Intrinsic Scale

Here I summarize some of the salient features of technicolor theories with technifermions in higher dimensional representations of the technicolor gauge group. The expected phase diagram as function of number of flavors and colors for the two index (anti)symmetric representation of the gauge group is reviewed. After having constructed the simplest walking technicolor theory one can show that it is not at odds with the precision measurements. The simplest theory also requires, for consistency, a fourth family of heavy leptons. The latter may result in an interesting signature at LHC. In the case of a fourth family of leptons with ordinary lepton hypercharge the new heavy neutrino can be a natural candidate of cold dark matter. New theories will also be proposed in which the critical number of flavors needed to enter the conformal window is higher than in the one with fermions in the two-index symmetric representation, but lower than in the walking technicolor theories with fermions only in the fundamental representation of the gauge group. Due to the near conformal/chiral phase transition the composite Higgs is very light compared to the intrinsic scale of the technicolor theory. For the two technicolor theory the composite Higgs mass is predicted not to exceed 150 GeV.

scholarly journals Dark Photon Searches at BESIII

2018 ◽  
Vol 46 ◽  
pp. 1860046 ◽  
Author(s):  
Dayong Wang
Keyword(s):  
Degrees Of Freedom ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Gauge Bosons ◽  
Data Set ◽  
Decay Modes ◽  
Dark Photon ◽  
The Standard Model ◽  
New Type ◽  
Low Mass

Many models beyond the Standard Model, motivated by the recent astrophysical anomalies, predict a new type of weak-interacting degrees of freedom. Typical models include the possibility of the low-mass dark gauge bosons of a few GeV and thus making them accessible at the BESIII experiment running at the tau-charm region. The BESIII has recently searched such dark bosons in several decay modes using the high statistics data set collected at charmonium resonaces. This talk will summarize the recent BESIII results of these dark photon searches and related new physics studies.

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