scholarly journals Towards Reviving Electroweak Baryogenesis with a Fourth Generation

2013 ◽  
Vol 2013 ◽  
pp. 1-9
Author(s):  
Wei-Shu Hou ◽  
Masaya Kohda
Keyword(s):  
Recent Observation ◽  
Baryon Asymmetry ◽  
Boson Mass ◽  
Fourth Generation ◽  
Higgs Boson Mass ◽  
Electroweak Phase Transition ◽  
Difficult Situation ◽  
First Order ◽  
The Standard Model ◽  
The Universe

Electroweak baryogenesis is an attractive scenario for explaining the baryon asymmetry of the universe. However, it does not work within the standard model due to two reasons: (1) the strength of CP violation from the Kobayashi-Maskawa mechanism with three generations is too small; (2) the electroweak phase transition is not first order for the experimentally allowed Higgs boson mass. We discuss possibilities to solve these problems by introducing a fourth generation of fermions and how electroweak baryogenesis might be revived. We also discuss briefly the recent observation of a Higgs-like boson with mass around 125 GeV, which puts the fourth generation in a difficult situation, and the possible way out.

scholarly journals Lepton-mediated electroweak baryogenesis, gravitational waves and the 4τ final state at the collider

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Ke-Pan Xie
Keyword(s):  
Phase Transition ◽  
Gravitational Waves ◽  
Parameter Space ◽  
Baryon Asymmetry ◽  
Hadron Colliders ◽  
Electroweak Phase Transition ◽  
Final State ◽  
First Order ◽  
The Standard Model ◽  
The Universe

Abstract An electroweak baryogenesis (EWBG) mechanism mediated by τ lepton transport is proposed. We extend the Standard Model with a real singlet scalar S to trigger the strong first-order electroweak phase transition (SFOEWPT), and with a set of leptophilic dimension-5 operators to provide sufficient CP violating source. We demonstrate this model is able to generate the observed baryon asymmetry of the universe. This scenario is experimentally testable via either the SFOEWPT gravitational wave signals at the next-generation space-based detectors, or the pp → h* → SS → 4τ process (where h* is an off-shell Higgs) at the hadron colliders. A detailed collider simulation shows that a considerable fraction of parameter space can be probed at the HL-LHC, while almost the whole parameter space allowed by EWBG can be reached by the 27 TeV HE-LHC.

scholarly journals Simulations of a bubble wall interacting with an electroweak plasma

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Zong-Gang Mou ◽  
Paul M. Saffin ◽  
Anders Tranberg
Keyword(s):  
Large Scale ◽  
Baryon Asymmetry ◽  
Winding Number ◽  
Bubble Wall ◽  
Electroweak Phase Transition ◽  
First Order ◽  
The Standard Model ◽  
Technical Details ◽  
Real Time Simulations ◽  
Chern Simons

Abstract We perform large-scale real-time simulations of a bubble wall sweeping through an out-of-equilibrium plasma. The scenario we have in mind is the electroweak phase transition, which may be first order in extensions of the Standard Model, and produce such bubbles. The process may be responsible for baryogenesis and can generate a background of primordial cosmological gravitational waves. We study thermodynamic features of the plasma near the advancing wall, the generation of Chern-Simons number/Higgs winding number and consider the potential for CP-violation at the wall generating a baryon asymmetry. A number of technical details necessary for a proper numerical implementation are developed.

BARYOGENESIS IN THE INFLATIONARY UNIVERSE —THE INSTANTANEOUS REHEATING MODEL—

1987 ◽  
Vol 02 (06) ◽  
pp. 1809-1828 ◽  
Author(s):  
JUN’ICHI YOKOYAMA ◽  
HIDEO KODAMA ◽  
KATSUHIKO SATO ◽  
NOBUAKI SATO
Keyword(s):  
Thermal Equilibrium ◽  
Large Scale ◽  
Baryon Asymmetry ◽  
Higgs Bosons ◽  
Boson Mass ◽  
Inflationary Universe ◽  
Higgs Boson Mass ◽  
Boltzmann Equations ◽  
Thermal Equilibrium State ◽  
The Universe

Baryogenesis in the inflationary universe is investigated, assuming that the universe is reheated instantaneously. Boltzmann equations are numerically integrated to trace time evolution of asymmetries in quarks and leptons in the Friedmann stage after the reheating, starting from the thermal equilibrium state. It is shown that the sign of the final baryon asymmetry may change depending on the reheating temperature as a result of interplay of superheavy gauge and Higgs bosons, and its mechanism is clarified. Furthermore we suggest a mechanism of generating isocurvature fluctuations which could be the origin of the large scale structure of the universe. It is also found in the instantaneous reheating model that the reheating temperature Ti must satisfy Ti>MH/10 (MH: Higgs boson mass) for the observed baryon/entropy ratio to be explained.

scholarly journals BOUNDS ON THE LIGHTEST HIGGS BOSON MASS WITH THREE AND FOUR FERMION GENERATIONS

1999 ◽  
Vol 14 (10) ◽  
pp. 1605-1632 ◽  
Author(s):  
DAVID DOOLING ◽  
KYUNGSIK KANG ◽  
SIN KYU KANG
Keyword(s):  
Higgs Boson ◽  
Lower Bounds ◽  
Higgs Mass ◽  
Upper Bounds ◽  
Boson Mass ◽  
Fourth Generation ◽  
Higgs Boson Mass ◽  
Supersymmetric Extension ◽  
Vacuum Stability ◽  
The Standard Model

We present lower bounds on the Higgs boson mass in the Standard Model with three and four fermion generations, SM (3,4), as well as upper bounds on the lightest Higgs boson mass in the minimal supersymmetric extension of the SM with three and four generations, MSSM (3,4). Our analysis utilizes the SM (3,4) renormalization-group-improved one-loop effective potential of the Higgs boson to find the upper bounds on the Higgs mass in the MSSM (3,4), while the lower bounds in the SM (3,4) are derived from considerations of vacuum stability. All the bounds increase as the degenerate fourth generation mass increases, providing more room in theory space that respects the increasing experimental lower limit of the Higgs mass.

scholarly journals SOURCE OF CP VIOLATION FOR THE BARYON ASYMMETRY OF THE UNIVERSE

2011 ◽  
Vol 20 (08) ◽  
pp. 1521-1532 ◽  
Author(s):  
GEORGE W. S. HOU
Keyword(s):  
Phase Transition ◽  
Cp Violation ◽  
Research Agenda ◽  
Baryon Asymmetry ◽  
Fourth Generation ◽  
Electroweak Phase Transition ◽  
The Universe

We give a description of why the existence of a fourth generation is likely to provide enough CP violation for baryogenesis, and trace how this observation came about. We survey the current experimental and theoretical pursuits and outline a research agenda, touching upon unitarity violation and very heavy chiral quarks, and comment on how the electroweak phase transition picture might be altered.

scholarly journals Search for dark photons in Higgs boson production via vector boson fusion in proton-proton collisions at $$ \sqrt{s} $$ = 13 TeV

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
A. M. Sirunyan ◽  
◽  
A. Tumasyan ◽  
W. Adam ◽  
T. Bergauer ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Confidence Level ◽  
Branching Fraction ◽  
Vector Boson ◽  
Boson Mass ◽  
Higgs Boson Mass ◽  
Vector Boson Fusion ◽  
Upper Limit ◽  
The Standard Model

Abstract A search is presented for a Higgs boson that is produced via vector boson fusion and that decays to an undetected particle and an isolated photon. The search is performed by the CMS collaboration at the LHC, using a data set corresponding to an integrated luminosity of 130 fb−1, recorded at a center-of-mass energy of 13 TeV in 2016–2018. No significant excess of events above the expectation from the standard model background is found. The results are interpreted in the context of a theoretical model in which the undetected particle is a massless dark photon. An upper limit is set on the product of the cross section for production via vector boson fusion and the branching fraction for such a Higgs boson decay, as a function of the Higgs boson mass. For a Higgs boson mass of 125 GeV, assuming the standard model production rates, the observed (expected) 95% confidence level upper limit on the branching fraction is 3.5 (2.8)%. This is the first search for such decays in the vector boson fusion channel. Combination with a previous search for Higgs bosons produced in association with a Z boson results in an observed (expected) upper limit on the branching fraction of 2.9 (2.1)% at 95% confidence level.

scholarly journals Electroweak baryogenesis and gravitational waves in a composite Higgs model with high dimensional fermion representations

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Ke-Pan Xie ◽  
Ligong Bian ◽  
Yongcheng Wu
Keyword(s):  
Form Factors ◽  
Higgs Doublet ◽  
Higgs Model ◽  
High Dimensional ◽  
Electroweak Phase Transition ◽  
First Order ◽  
Composite Higgs ◽  
Future Space ◽  
The Universe ◽  
Scalar Sector

Abstract We study electroweak baryogenesis in the SO(6)/SO(5) composite Higgs model with the third generation quarks being embedded in the 20′ representation of SO(6). The scalar sector contains one Higgs doublet and one real singlet, and their potential is given by the Coleman-Weinberg potential evaluated from the form factors of the lightest vector and fermion resonances. We show that the resonance masses at $$ \mathcal{O}\left(1\sim 10\kern0.5em \mathrm{TeV}\right) $$ O 1 ∼ 10 TeV can generate a potential that triggers the strong first-order electroweak phase transition (SFOEWPT). The CP violating phase arising from the dimension-6 operator in the top sector is sufficient to yield the observed baryon asymmetry of the universe. The SFOEWPT parameter space is detectable at the future space-based detectors.

scholarly journals Nucleation is more than critical: A case study of the electroweak phase transition in the NMSSM

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Sebastian Baum ◽  
Marcela Carena ◽  
Nausheen R. Shah ◽  
Carlos E. M. Wagner ◽  
Yikun Wang
Keyword(s):  
Phase Transition ◽  
Parameter Space ◽  
Local Minima ◽  
Critical Temperatures ◽  
Electroweak Phase Transition ◽  
First Order ◽  
Vacuum Structure ◽  
The Universe ◽  
Scalar Sector

Abstract Electroweak baryogenesis is an attractive mechanism to generate the baryon asymmetry of the Universe via a strong first order electroweak phase transition. We compare the phase transition patterns suggested by the vacuum structure at the critical temperatures, at which local minima are degenerate, with those obtained from computing the probability for nucleation via tunneling through the barrier separating local minima. Heuristically, nucleation becomes difficult if the barrier between the local minima is too high, or if the distance (in field space) between the minima is too large. As an example of a model exhibiting such behavior, we study the Next-to-Minimal Supersymmetric Standard Model, whose scalar sector contains two SU(2) doublets and one gauge singlet. We find that the calculation of the nucleation probabilities prefers different regions of parameter space for a strong first order electroweak phase transition than the calculation based solely on the critical temperatures. Our results demonstrate that analyzing only the vacuum structure via the critical temperatures can provide a misleading picture of the phase transition patterns, and, in turn, of the parameter space suitable for electroweak baryogenesis.

Ring-diagram summations in the finite-temperature effective potential

1993 ◽  
Vol 71 (5-6) ◽  
pp. 227-236 ◽  
Author(s):  
M. E. Carrington
Keyword(s):  
Phase Transition ◽  
Standard Model ◽  
Effective Potential ◽  
Finite Temperature ◽  
Electroweak Phase Transition ◽  
First Order ◽  
Ring Diagram ◽  
First Order Phase Transition ◽  
The Standard Model ◽  
The One

There has been much recent interest in the finite-temperature effective potential of the standard model in the context of the electroweak phase transition. We review the calculation of the effective potential with particular emphasis on the validity of the expansions that are used. The presence of a term that is cubic in the Higgs condensate in the one-loop effective potential appears to indicate a first-order electroweak phase transition. However, in the high-temperature regime, the infrared singularities inherent in massless models produce cubic terms that are of the same order in the coupling. In this paper, we discuss the inclusion of an infinite set of these terms via the ring-diagram summation, and show that the standard model has a first-order phase transition in the weak coupling expansion.

scholarly journals The Electroweak Phase Transition in a Spontaneously Magnetized Plasma

2019 ◽  
Vol 64 (8) ◽  
pp. 710
Author(s):  
P. Minaiev ◽  
V. Skalozub
Keyword(s):  
Phase Transition ◽  
Higgs Boson ◽  
Magnetic Fields ◽  
Spontaneous Magnetization ◽  
Higgs Doublet ◽  
Magnetized Plasma ◽  
Boson Mass ◽  
Spontaneous Generation ◽  
Electroweak Phase Transition ◽  
First Order

We investigate the electroweak phase transition (EWPT) in the Minimal (One Higgs doublet) Standard Model (SM) with account for the spontaneous generation of magnetic and chromo-magnetic fields. As it is known, in the SM for the mass of a Higgs boson greater than 75 GeV, this phase transition is of the second order. But, according to Sakharov’s conditions for the formation of the baryon asymmetry in the early Universe, it has to be strongly of the first order. In the Two Higgs doublets SM, there is a parametric space, where the first-order phase transition is realized for the realistic Higgs boson mass mH = 125 GeV. On the other hand, in the hot Universe, the spontaneous magnetization of a plasma had happened. The spontaneously generated (chromo) magnetic fields are temperature-dependent. They influence the EWРT. The color chromomagnetic fields B3 and B8 are created spontaneously in the gluon sector of QCD at a temperature T > Td higher the deconfinement temperature Td. The usual magnetic field H has also to be spontaneously generated. For T close to the TEWPT , these magnetic fields could change the kind of the phase transition.

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