scholarly journals E6 GUT and Baryon Asymmetry Generation in the E6CHM

Universe ◽  
2022 ◽  
Vol 8 (1) ◽  
pp. 33
Author(s):  
Roman Nevzorov
Keyword(s):  
Gauge Group ◽  
Top Quark ◽  
Gauge Coupling ◽  
Baryon Number ◽  
Higgs Doublet ◽  
Anomaly Cancellation ◽  
Strongly Coupled ◽  
Weakly Coupled ◽  
Low Energies ◽  
The Right

Grand unified theories (GUTs) may result in the E6-inspired composite Higgs model (E6CHM) at low energies, almost stabilizing the electroweak scale. We consider an orbifold GUT in 6 dimensions in which the E6-gauge group is broken to the gauge symmetry of the standard model (SM) while different multiplets of the SM fermions come from different 27-plets. The strongly coupled sector of the E6CHM is confined on the brane where E6 is broken down to its SU(6) subgroup. Near the scale of f≳5TeV, this approximate SU(6) symmetry is expected to be further broken down to its SU(5) subgroup, which contains the SM-gauge group. Such a breakdown leads to a set of pseudo-Nambu–Goldstone bosons (pNGBs) that includes an SM-like Higgs doublet. The approximate gauge coupling unification in the E6CHM takes place at high energies when the right-handed top quark is a composite fermion. To ensure anomaly cancellation, the weakly coupled sector of this model contains extra exotic matter beyond the SM. We discuss the mechanism of the generation of matter–antimatter asymmetry within the variant of the E6CHM in which the baryon number and CP invariance are violated.

scholarly journals MIRAGE GAUGE COUPLING UNIFICATION AND TeV SCALE STRINGS

2000 ◽  
Vol 15 (05) ◽  
pp. 343-350 ◽  
Author(s):  
EDI HALYO
Keyword(s):  
Standard Model ◽  
Gauge Group ◽  
Gauge Theories ◽  
Gauge Coupling ◽  
Constant Independent ◽  
Addition Formula ◽  
Strongly Coupled ◽  
Weakly Coupled ◽  
Low Energies ◽  
Independent Constant

We consider gauge coupling unification in models with TeV scale strings and large compact dimensions realized as type IIB string orientifolds. Following an observation by Ibanez we show that the gauge couplings at low energies can behave as if they effectively unify at MU~2 × 1016 GeV with αU~1/24. This requires the σ model anomaly coefficients [Formula: see text] not to be all equal and their ratio to the β-functions of minimally supersymmetric standard model βa to be a constant independent of the gauge group. If, in addition, [Formula: see text] have a gauge group independent constant piece, the relation between the unified gauge coupling and the dilaton vev is modified so that there can be weakly coupled gauge theories arising from strongly coupled strings.

scholarly journals A Review of the Exceptional Supersymmetric Standard Model

Symmetry ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 557
Author(s):  
Stephen F. King ◽  
Stefano Moretti ◽  
Roman Nevzorov
Keyword(s):  
Gauge Symmetry ◽  
Standard Model ◽  
Supersymmetric Standard Model ◽  
Hadron Collider ◽  
Gauge Coupling ◽  
Higgs Bosons ◽  
Anomaly Cancellation ◽  
Flavor Changing ◽  
Low Energies ◽  
The Right

Local supersymmetry (SUSY) provides an attractive framework for the incorporation of gravity and unification of gauge interactions within Grand Unified Theories (GUTs). Its breakdown can lead to a variety of models with softly broken SUSY at low energies. In this review article, we focus on the SUSY extension of the Standard Model (SM) with an extra U ( 1 ) N gauge symmetry originating from a string-inspired E 6 GUTs. Only in this U ( 1 ) extension of the minimal supersymmetric standard model (MSSM) can the right-handed neutrinos be superheavy, providing a mechanism for the baryon asymmetry generation. The particle content of this exceptional supersymmetric standard model (E 6 SSM) includes three 27 representations of the E 6 group, to ensure anomaly cancellation. In addition it also contains a pair of S U ( 2 ) W doublets as required for the unification of gauge couplings. Thus, E 6 SSM involves exotic matter beyond the MSSM. We consider symmetries that permit suppressing flavor changing processes and rapid proton decay, as well as gauge coupling unification, the gauge symmetry breaking and the spectrum of Higgs bosons in this model. The possible Large Hadron Collider (LHC) signatures caused by the presence of exotic states are also discussed.

scholarly journals $$U(1)'$$ extensions of the $$\mu \nu \mathrm{SSM}$$

2021 ◽  
Vol 81 (5) ◽  
Author(s):  
J. A. Aguilar-Saavedra ◽  
I. Lara ◽  
D. E. López-Fogliani ◽  
C. Muñoz
Keyword(s):  
Dark Matter ◽  
Domain Wall ◽  
Standard Model ◽  
Gauge Group ◽  
Parameter Space ◽  
Baryon Number ◽  
Anomaly Cancellation ◽  
The Standard Model ◽  
Different Types ◽  
Visible Sector

AbstractIn the $$\mu \nu $$ μ ν SSM, the presence of R-parity violating couplings involving right-handed (RH) neutrinos solves simultaneously the $$\mu $$ μ - and $$\nu $$ ν -problems. We explore extensions of the $$\mu \nu $$ μ ν SSM adding a $$U(1)'$$ U ( 1 ) ′ gauge group, which provides the RH neutrinos with a non-vanishing charge. In these models, dubbed U$$\mu \nu $$ μ ν SSM, the anomaly cancellation conditions impose the presence of exotic quarks in the spectrum that are vector-like under the standard model (SM) gauge group: either three pairs SU(2) quark singlets, or a pair of quark singlets together with a pair of quark doublets. Several singlets under the SM group can also be present, with the $$U(1)'$$ U ( 1 ) ′ charges making distinctions among them, and therefore allowing different types of couplings. Some of these singlets dynamically generate Majorana masses for the RH neutrinos, and others can be candidates for dark matter. The useful characteristics of models with $$U(1)'$$ U ( 1 ) ′ s are also present in U$$\mu \nu $$ μ ν SSM models: baryon-number-violating operators as well as explicit Majorana masses and $$\mu $$ μ terms are forbidden, and the domain wall problem is avoided. The phenomenology of U$$\mu \nu $$ μ ν SSM models is very rich. We analyze the experimental constraints on their parameter space, specially on the mass and mixing of the new $$Z'$$ Z ′ boson. In addition to the exotic quarks, which can hadronize inside the detector or decay producing SM particles, the U$$\mu \nu $$ μ ν SSM models can also have new signals such as decays of the $$Z'$$ Z ′ to sparticle pairs like right sneutrinos, charginos or neutralinos. Besides, $$Z'$$ Z ′ and Higgs mediated annihilations and interactions with the visible sector of WIMP dark matter particles, can also be present.

scholarly journals Generation of baryon asymmetry in the E6CHM

2018 ◽  
Vol 191 ◽  
pp. 02004
Author(s):  
Roman Nevzorov ◽  
Anthony Thomas
Keyword(s):  
Baryon Number ◽  
Discrete Symmetry ◽  
Higgs Doublet ◽  
Lepton Number ◽  
Global Symmetry ◽  
Goldstone Bosons ◽  
Composite Higgs ◽  
Weakly Coupled ◽  
Baryon Number Violation ◽  
Near Future

The strongly interacting sector in the E6 inspired composite Higgs model (E6CHM) with baryon number violation possesses an SU(6) × U(1)L global symmetry. In the weakly-coupled sector of this model the U(1)L symmetry associated with lepton number conservation is broken down to a ZL2 discrete symmetry, which stabilizes the proton. Near the scale f ≳ 10 TeV the SU(6) symmetry is broken down to its SU(5) subgroup, giving rise to a set of pseudo- Nambu-Goldstone bosons (pNGBs) that involves the SM-like Higgs doublet, a scalar coloured triplet and a SM singlet boson. Because f is so high, all baryon number violating operators are sufficiently strongly suppressed. Nevertheless, in this variant of the E6CHM the observed matter-antimatter asymmetry can be induced if CP is violated. The pNGB scalar coloured triplet plays a key role in this process and leads to a distinct signature that may be detected at the LHC in the near future.

scholarly journals THE MINIMAL SUPERSYMMETRIC STANDARD MODEL

1996 ◽  
Vol 11 (08) ◽  
pp. 599-613 ◽  
Author(s):  
CSABA CSÁKI
Keyword(s):  
Standard Model ◽  
Mass Parameter ◽  
Baryon Number ◽  
Higgs Doublet ◽  
Particle Content ◽  
Anomaly Cancellation ◽  
Flavor Changing ◽  
Quantum Numbers ◽  
Parity Conservation ◽  
The One

The structure of the MSSM is reviewed. We first motivate the particle content of the theory by examining the quantum numbers of the known standard model particles and by the requirement of anomaly cancellation. Once the particle content is fixed we can write down the most general renormalizable superpotential. However such a superpotential will contain terms breaking lepton and baryon number which leads us to the concept of R-parity conservation. The question of supersymmetry breaking is discussed next. We list the possible soft breaking terms. However the Lagrangian involving the most general soft breaking terms is phenomenologically intractable because of the appearance of many new parameters. It also leads to some unacceptable predictions. To reduce the number of parameters we restrict ourselves to the case with universal soft breaking terms at the GUT scale. We motivate the need for universal soft breaking terms by the apparent unification of gauge couplings in the MSSM and by the absence of flavor changing neutral currents. Then we discuss radiative electroweak symmetry breaking. Radiative breaking arises because the one-loop corrections involving the large top Yukawa coupling change the sign of the soft breaking mass parameter of the up-type Higgs doublet, this way introducing a nontrivial minimum in the Higgs potential. Finally we give an overview of the possible mixings in the MSSM and enumerate the physical (mass eigenstate) fields together with the mass matrices.

scholarly journals CFT unitarity and the AdS Cutkosky rules

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
David Meltzer ◽  
Allic Sivaramakrishnan
Keyword(s):  
Flat Space ◽  
Tree Level ◽  
Optical Theorem ◽  
Conformal Field Theories ◽  
Strongly Coupled ◽  
Conformal Field ◽  
Weakly Coupled ◽  
S Matrix ◽  
Space Limit ◽  
Diagrammatic Method

Abstract We derive the Cutkosky rules for conformal field theories (CFTs) at weak and strong coupling. These rules give a simple, diagrammatic method to compute the double-commutator that appears in the Lorentzian inversion formula. We first revisit weakly-coupled CFTs in flat space, where the cuts are performed on Feynman diagrams. We then generalize these rules to strongly-coupled holographic CFTs, where the cuts are performed on the Witten diagrams of the dual theory. In both cases, Cutkosky rules factorize loop diagrams into on-shell sub-diagrams and generalize the standard S-matrix cutting rules. These rules are naturally formulated and derived in Lorentzian momentum space, where the double-commutator is manifestly related to the CFT optical theorem. Finally, we study the AdS cutting rules in explicit examples at tree level and one loop. In these examples, we confirm that the rules are consistent with the OPE limit and that we recover the S-matrix optical theorem in the flat space limit. The AdS cutting rules and the CFT dispersion formula together form a holographic unitarity method to reconstruct Witten diagrams from their cuts.

scholarly journals Prandtl Number in Classical Hard-Sphere and One-Component Plasma Fluids

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 821
Author(s):  
Sergey Khrapak ◽  
Alexey Khrapak
Keyword(s):  
Prandtl Number ◽  
Hard Sphere ◽  
Solid Phase ◽  
Freezing Point ◽  
Three Dimensional ◽  
Order Unity ◽  
Strongly Coupled ◽  
Dielectric Fluids ◽  
Weakly Coupled ◽  
Component Plasma

The Prandtl number is evaluated for the three-dimensional hard-sphere and one-component plasma fluids, from the dilute weakly coupled regime up to a dense strongly coupled regime near the fluid-solid phase transition. In both cases, numerical values of order unity are obtained. The Prandtl number increases on approaching the freezing point, where it reaches a quasi-universal value for simple dielectric fluids of about ≃1.7. Relations to two-dimensional fluids are briefly discussed.

Article

1999 ◽  
Vol 77 (11) ◽  
pp. 1810-1812 ◽  
Author(s):  
Alex D Bain
Keyword(s):  
Spin System ◽  
Coupled System ◽  
Coupled Systems ◽  
Physical Reason ◽  
Strongly Coupled ◽  
System Combination ◽  
First Order ◽  
Weakly Coupled ◽  
Quantum Transitions ◽  
Weakly Coupled Systems

Strongly coupled spin systems provide many curious and interesting effects in NMR spectra, one of which is the presence of unexpected (from a first-order viewpoint) lines. A physical reason is given for the presence of these combination lines. The X part of the spectrum of an ABX spin system is analysed as an example. For an ABX system, it is well known that the AB nuclei give a spectrum consisting of two AB-type spectra, corresponding to the two orientations of the X nucleus. It can also be shown that the X part of the spectrum corresponds to the X nucleus undergoing a transition in the presence of an AB-like spin system. For weakly coupled systems, the four observed lines correspond to the four different orientations of the A and B nuclei. For a strongly coupled system, two additional lines may appear, the combination lines. The resulting six lines correspond to the four spin orientations, plus the two zero-quantum transitions. It is shown that these six lines are such that there is no net excitation of the AB-like spin system associated with the X transitions. There is no AB coherence created directly by a pulse applied to X. AB coherence is created as the system evolves, and this is responsible for many of the curious effects. This is shown to be true for all spin sub-systems, which are weakly coupled to a strongly coupled sub-system.Key words: NMR, strong coupling, second-order spectra, ABX spin system, combination lines, spectral analysis.

scholarly journals SCALAR DARK MATTER EFFECTS IN HIGGS AND TOP QUARK DECAYS

2007 ◽  
Vol 22 (25n28) ◽  
pp. 2121-2129 ◽  
Author(s):  
XIAO-GANG HE ◽  
HO-CHIN TSAI ◽  
TONG LI ◽  
XUE-QIAN LI
Keyword(s):  
Dark Matter ◽  
Top Quark ◽  
Neutral Current ◽  
Higgs Doublet ◽  
Tree Level ◽  
Flavor Changing ◽  
Higgs Decay ◽  
Dark Matter Relic Density ◽  
Flavor Changing Neutral Current ◽  
Two Higgs Doublet Model

We study possible observational effects of scalar dark matter, the darkon D, in Higgs h and top quark t decay processes, h → DD and t → cDD in the minimal Standard Model (SM) and its two Higgs doublet model (THDM) extension supplemented with a SM singlet darkon scalar field D. We find that the darkon D can have a mass in the range of sub-GeV to several tens of GeV, interesting for LHC and ILC colliders, to produce the required dark matter relic density. In the SM with a darkon, t → cDD only occurs at loop level giving a very small rate, while the rate for Higgs decay h → DD can be large. In THDM III with a darkon, where tree level flavor changing neutral current (FCNC) interaction exists, a sizable rate for t → cDD is also possible.

scholarly journals On the Interpretation of Nonresonant Phenomena at Colliders

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Miguel G. Folgado ◽  
Veronica Sanz
Keyword(s):  
New Physics ◽  
Derivative Expansion ◽  
Strongly Coupled ◽  
Null Results ◽  
Goldstone Bosons ◽  
Physics Potential ◽  
Low Energies ◽  
Light Particles ◽  
Integrated Luminosity

With null results in resonance searches at the LHC, the physics potential focus is now shifting towards the interpretation of nonresonant phenomena. An example of such shift is the increased popularity of the EFT programme. We can embark on such programme owing to the good integrated luminosity and an excellent understanding of the detectors, which will allow these searches to become more intense as the LHC continues. In this paper, we provide a framework to perform this interpretation in terms of a diverse set of scenarios, including (1) generic heavy new physics described at low energies in terms of a derivative expansion, such as in the EFT approach; (2) very light particles with derivative couplings, such as axions or other light pseudo-Goldstone bosons; and (3) the effect of a quasicontinuum of resonances, which can come from a number of strongly coupled theories, extradimensional models, clockwork set-ups, and their deconstructed cousins. These scenarios are not equivalent despite all nonresonance, although the matching among some of them is possible, and we provide it in this paper.

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