scholarly journals The Higgs profile in the standard model and beyond

2019 ◽  
Vol 65 (5 Sept-Oct) ◽  
pp. 419 ◽  
Author(s):  
L. Díaz Cruz
Keyword(s):  
Dark Matter ◽  
Higgs Physics ◽  
Higgs Mass ◽  
Higgs Sector ◽  
New Physics ◽  
Special Focus ◽  
Higgs Particle ◽  
The Standard Model ◽  
The Right ◽  
Production Mechanisms

We present a review of Higgs physics in the SM and beyond, including the tests of the Higgs boson properties that have been performed at LHC and have permitted to delineate its profile. After presenting the essential features of the BEH mechanism, and its implementation in the SM, we discuss how the Higgs mass limits developed over the years. These constraints in turn helped to classify the Higgs phenomenology (decays and production mechanisms), which provided the right direction to search for the Higgs particle, an enterprise that culminated with its discovery at LHC. So far, the constraints on the couplings of the Higgs particle, point towards a SM interpretation. However, the SM has open ends that suggest the need to look for extensions of the model. We discuss in general the connection of the Higgs sector with some new physics (e.g. supersymmetry, flavor and Dark matter), with special focus on a more flavored Higgs sector. Thus is realized in the most general 2HDM, and its textured version, which we study in general, and for its various limits, which contain distinctive flavor-violating signals that could be searched at current and future colliders.

scholarly journals CP VIOLATIONS (AND MORE) AFTER THE FIRST TWO YEARS OF LHCB

2013 ◽  
Vol 53 (A) ◽  
pp. 528-533
Author(s):  
Giulio Auriemma
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Particle Physics ◽  
Hadron Collider ◽  
Higgs Sector ◽  
New Physics ◽  
Baryon Asymmetry ◽  
Open Problems ◽  
Cp Violations ◽  
The Standard Model

The most interesting cosmological open problems, baryon asymmetry, dark matter, inflation and dark energy, are not explained by the standard model of particle physics (SM). The final<br />goal of the Large Hadron Collider an experimental verification of the SM in the Higgs sector, and also a search for evidence of new physics beyond it. In this paper we will report some of the results obtained in 2010 and 2011, from the LHCb experiment dedicated to the study of CP violations and rare decays of heavy quarks.

scholarly journals A REVIEW OF NATURALNESS AND DARK MATTER PREDICTION FOR THE HIGGS MASS IN MSSM AND BEYOND

2012 ◽  
Vol 27 (02) ◽  
pp. 1230003 ◽  
Author(s):  
S. CASSEL ◽  
D. M. GHILENCEA
Keyword(s):  
Dark Matter ◽  
Higgs Mass ◽  
Higgs Sector ◽  
New Physics ◽  
Fine Tuning ◽  
Quantum Corrections ◽  
Electroweak Scale ◽  
A Value ◽  
8 Tev ◽  
Effective Operators

Within a two-loop leading-log approximation, we review the prediction for the lightest Higgs mass (mh) in the framework of constrained MSSM (CMSSM), derived from the naturalness requirement of minimal fine-tuning (Δ) of the electroweak scale, and dark matter consistency. As a result, the Higgs mass is predicted to be just above the LEP2 bound, mh = 115.9±2 GeV , corresponding to a minimal Δ = 17.8, the value obtained from consistency with electroweak and WMAP (3σ) constraints, but without the LEP2 bound. Due to quantum corrections (largely QCD ones for mh above LEP2 bound), Δ grows ≈ exponentially on either side of the above value of mh, which stresses the relevance of this prediction. A value mh>121 (126) GeV cannot be accommodated within the CMSSM unless one accepts a fine-tuning cost worse than Δ>100 (1000), respectively. We review how the above prediction for mh and Δ changes under the addition of new physics beyond the MSSM Higgs sector, parametrized by effective operators of dimensions d = 5 and d = 6. For d = 5 operators, one can obtain values mh as large as 130 GeV with an acceptable Δ<10. The size of the supersymmetric correction that each individual operator of d = 6 brings to the value of mh for points with Δ<100 (<200), is found to be small, of few ≤4 GeV (≤6 GeV) respectively, for M = 8 TeV where M is the scale of new physics. This value decreases (increases) by approximately 1 GeV for a 1 TeV increase (decrease) of the scale M. The relation of these results to the Atlas/CMS supersymmetry exclusion limits is presented together with their impact for the CMSSM regions of lowest fine-tuning.

scholarly journals Electroweak symmetry non-restoration from dark matter

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Oleksii Matsedonskyi ◽  
James Unwin ◽  
Qingyun Wang
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Higgs Mass ◽  
Direct Detection ◽  
Higgs Doublet ◽  
New Physics ◽  
Electroweak Symmetry ◽  
The Standard Model ◽  
New States ◽  
Potential Remedy

Abstract Restoration of the electroweak symmetry at temperatures around the Higgs mass is linked to tight phenomenological constraints on many baryogenesis scenarios. A potential remedy can be found in mechanisms of electroweak symmetry non-restoration (SNR), in which symmetry breaking is extended to higher temperatures due to new states with couplings to the Standard Model. Here we show that, in the presence of a second Higgs doublet, SNR can be realized with only a handful of new fermions which can be identified as viable dark matter candidates consistent with all current observational constraints. The competing requirements on this class of models allow for SNR at temperatures up to ∼TeV, and imply the presence of sub-TeV new physics with sizable interactions with the Standard Model. As a result this scenario is highly testable with signals in reach of next-generation collider and dark matter direct detection experiments.

scholarly journals Standard Model prediction of the Bc lifetime

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Jason Aebischer ◽  
Benjamín Grinstein
Keyword(s):  
Standard Model ◽  
Model Prediction ◽  
Strange Quark ◽  
Standard Model Prediction ◽  
New Physics ◽  
Operator Product ◽  
Special Focus ◽  
Third Order ◽  
Clear Cut ◽  
The Standard Model

Abstract Applying an operator product expansion approach we update the Standard Model prediction of the Bc lifetime from over 20 years ago. The non-perturbative velocity expansion is carried out up to third order in the relative velocity of the heavy quarks. The scheme dependence is studied using three different mass schemes for the $$ \overline{b} $$ b ¯ and c quarks, resulting in three different values consistent with each other and with experiment. Special focus has been laid on renormalon cancellation in the computation. Uncertainties resulting from scale dependence, neglecting the strange quark mass, non-perturbative matrix elements and parametric uncertainties are discussed in detail. The resulting uncertainties are still rather large compared to the experimental ones, and therefore do not allow for clear-cut conclusions concerning New Physics effects in the Bc decay.

scholarly journals Sterile Neutrinos as Dark Matter: Alternative Production Mechanisms in the Early Universe

Universe ◽  
2021 ◽  
Vol 7 (8) ◽  
pp. 264
Author(s):  
Daniel Boyanovsky
Keyword(s):  
Dark Matter ◽  
Distribution Function ◽  
Kinetic Equation ◽  
Standard Model ◽  
Early Universe ◽  
Quantum Kinetic Equation ◽  
Sterile Neutrinos ◽  
The Standard Model ◽  
Production Mechanisms ◽  
Freeze Out

We study various production mechanisms of sterile neutrinos in the early universe beyond and within the standard model. We obtain the quantum kinetic equations for production and the distribution function of sterile-like neutrinos at freeze-out, from which we obtain free streaming lengths, equations of state and coarse grained phase space densities. In a simple extension beyond the standard model, in which neutrinos are Yukawa coupled to a Higgs-like scalar, we derive and solve the quantum kinetic equation for sterile production and analyze the freeze-out conditions and clustering properties of this dark matter constituent. We argue that in the mass basis, standard model processes that produce active neutrinos also yield sterile-like neutrinos, leading to various possible production channels. Hence, the final distribution function of sterile-like neutrinos is a result of the various kinematically allowed production processes in the early universe. As an explicit example, we consider production of light sterile neutrinos from pion decay after the QCD phase transition, obtaining the quantum kinetic equation and the distribution function at freeze-out. A sterile-like neutrino with a mass in the keV range produced by this process is a suitable warm dark matter candidate with a free-streaming length of the order of few kpc consistent with cores in dwarf galaxies.

scholarly journals The Search for Feebly Interacting Particles

2021 ◽  
Vol 71 (1) ◽  
pp. 279-313
Author(s):  
Gaia Lanfranchi ◽  
Maxim Pospelov ◽  
Philip Schuster
Keyword(s):  
Dark Matter ◽  
Particle Physics ◽  
Interaction Strength ◽  
New Physics ◽  
Fine Tuning ◽  
Experimental Program ◽  
Interacting Particles ◽  
Fundamental Physics ◽  
The Standard Model ◽  
The Universe

At the dawn of a new decade, particle physics faces the challenge of explaining the mystery of dark matter, the origin of matter over antimatter in the Universe, the apparent fine-tuning of the electroweak scale, and many other aspects of fundamental physics. Perhaps the most striking frontier to emerge in the search for answers involves New Physics at mass scales comparable to that of familiar matter—below the GeV scale but with very feeble interaction strength. New theoretical ideas to address dark matter and other fundamental questions predict such feebly interacting particles (FIPs) at these scales, and existing data may even provide hints of this possibility. Emboldened by the lessons of the LHC, a vibrant experimental program to discover such physics is underway, guided by a systematic theoretical approach that is firmly grounded in the underlying principles of the Standard Model. We give an overview of these efforts, their motivations, and the decadal goals that animate the community involved in the search for FIPs, and we focus in particular on accelerator-based experiments.

LOW ENERGY EFFECTIVE LAGRANGIAN FOR SUPERSYMMETRIC SEESAW MODEL

2007 ◽  
Vol 16 (05) ◽  
pp. 1437-1443
Author(s):  
AKINA KATO ◽  
TAKUYA MOROZUMI ◽  
NORIMI YOKOZAKI ◽  
SYN KYU KANG
Keyword(s):  
Neutrino Mass ◽  
Higgs Mass ◽  
Higgs Sector ◽  
Low Energy ◽  
Seesaw Model ◽  
Mass Correction ◽  
Effective Lagrangian ◽  
The One ◽  
The Right ◽  
Higgs Fields

Seesaw model is an attractive model because it may explain baryogenesis through leptogenesis and also may explain the small neutrino mass. The supersymmetric seesaw model may be more attractive because the naturalness problem is absent in supersymmetric theory. Recently, the higgs mass correction due to leptons and sleptons loops is computed.1 In this talk, we report on the preliminary results on the one loop corrections of leptons and sleptons loops to the effective action of Higgs sector for super symmetric seesaw model. Our results show that the corrections to the mass parameters for Higgs sector are proportional to the soft breaking parameters of supersymmetric seesaw model, while for the quartic couplings of Higgs fields, the corrections are suppressed by inverse powers of the right-handed neutrino mass.

scholarly journals Symmergent Gravity, Seesawic New Physics, and Their Experimental Signatures

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Durmuş Demir
Keyword(s):  
Dark Matter ◽  
Gamma Rays ◽  
Planck Scale ◽  
New Physics ◽  
Fine Tuning ◽  
Dark Matter Candidate ◽  
Uv Sensitivity ◽  
Gauge Symmetries ◽  
The Standard Model ◽  
Zero Coupling

The standard model of elementary particles (SM) suffers from various problems, such as power-law ultraviolet (UV) sensitivity, exclusion of general relativity (GR), and absence of a dark matter candidate. The LHC experiments, according to which the TeV domain appears to be empty of new particles, started sidelining TeV-scale SUSY and other known cures of the UV sensitivity. In search for a remedy, in this work, it is revealed that affine curvature can emerge in a way restoring gauge symmetries explicitly broken by the UV cutoff. This emergent curvature cures the UV sensitivity and incorporates GR as symmetry-restoring emergent gravity (symmergent gravity, in brief) if a new physics sector (NP) exists to generate the Planck scale and if SM+NP is Fermi-Bose balanced. This setup, carrying fingerprints of trans-Planckian SUSY, predicts that gravity is Einstein (no higher-curvature terms), cosmic/gamma rays can originate from heavy NP scalars, and the UV cutoff might take right value to suppress the cosmological constant (alleviating fine-tuning with SUSY). The NP does not have to couple to the SM. In fact, NP-SM coupling can take any value from zero to ΛSM2/ΛNP2 if the SM is not to jump from ΛSM≈500  GeV to the NP scale ΛNP. The zero coupling, certifying an undetectable NP, agrees with all the collider and dark matter bounds at present. The seesawic bound ΛSM2/ΛNP2, directly verifiable at colliders, implies that (i) dark matter must have a mass ≲ΛSM, (ii) Higgs-curvature coupling must be ≈1.3%, (iii) the SM RGEs must remain nearly as in the SM, and (iv) right-handed neutrinos must have a mass ≲1000  TeV. These signatures serve as a concise testbed for symmergence.

scholarly journals SIMPLE TWO HIGGS DOUBLET MODEL

2008 ◽  
Vol 23 (32) ◽  
pp. 5159-5172 ◽  
Author(s):  
RENATA JORA ◽  
SHERIF MOUSSA ◽  
SALAH NASRI ◽  
JOSEPH SCHECHTER ◽  
M. NAEEM SHAHID
Keyword(s):  
Dark Matter ◽  
Higgs Sector ◽  
Higgs Doublet ◽  
Dark Matter Candidate ◽  
Higgs Particle ◽  
Doublet Model ◽  
Two Higgs Doublet Model

We study a simple two-Higgs doublet model which reflects, in a phenomenological way, the idea of compositeness for the Higgs sector. It is relatively predictive. In one scenario, it allows for a "hidden" usual Higgs particle in the 100 GeV region and a possible dark matter candidate.

scholarly journals Flipped U(1) extended standard model and Majorana dark matter

2020 ◽  
Vol 80 (12) ◽  
Author(s):  
Cao H. Nam
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Boson Mass ◽  
Type I ◽  
Seesaw Mechanism ◽  
Gauge Symmetries ◽  
The Standard Model ◽  
Gauge Boson Mass ◽  
The Right ◽  
Relic Abundance

AbstractWe propose a general flavor-independent extension of the Standard Model (SM) with the minimal particle content, based on the symmetry $$SU(3)_C\times SU(2)_L\times U(1)_{Y'}\times U(1)_X\times Z_2$$ S U ( 3 ) C × S U ( 2 ) L × U ( 1 ) Y ′ × U ( 1 ) X × Z 2 . In this scenario, the charge operator is identified in terms of the charges of two U(1) gauge symmetries. The light neutrino masses are generated via Type-I seesaw mechanism only with two heavy right-handed neutrinos acquiring their Majorana masses through the $$U(1)_{Y'}\times U(1)_X$$ U ( 1 ) Y ′ × U ( 1 ) X symmetry breaking. We study various experimental constraints on the parameters of the model and investigate the phenomenology of the right-handed neutrino dark matter (DM) candidate assigned a $$Z_2$$ Z 2 -odd parity. We find that the most important constraints are the observed DM relic abundance, the current LHC limits, and the ambiguity of the SM neutral gauge boson mass.

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