scholarly journals Revisiting the decoupling effects in the running of the Cosmological Constant

2018 ◽  
Vol 33 (34) ◽  
pp. 1845013
Author(s):  
Oleg Antipin ◽  
Blaženka Melić
Keyword(s):  
Cosmological Constant ◽  
Higgs Mass ◽  
Vacuum Energy ◽  
Fine Tuning ◽  
Simple Extension ◽  
Heavy Particles ◽  
Entire Energy Range ◽  
The Standard Model ◽  
Entire Energy ◽  
Mass Dependent

We revisit the decoupling effects associated with heavy particles in the renormalization group running of the vacuum energy in a mass-dependent renormalization scheme. We find the running of the vacuum energy stemming from the Higgs condensate in the entire energy range and show that it behaves as expected from the simple dimensional arguments, meaning that it exhibits the quadratic sensitivity to the mass of the heavy particles in the infrared regime. The consequence of such a running to the fine-tuning problem with the measured value of the Cosmological Constant is analyzed and the constraint on the mass spectrum of a given model is derived. We show that in the Standard Model (SM) this fine-tuning constraint is not satisfied while in the massless theories this constraint formally coincides with the well-known Veltman condition. We also provide a remarkably simple extension of the SM where saturation of this constraint enables us to predict the radiative Higgs mass correctly. Generalization to constant curvature spaces is also given.

scholarly journals HIGGS MASS FROM A CASIMIR ENERGY INDUCED COSMOLOGICAL CONSTANT IN THE STANDARD MODEL

2004 ◽  
Vol 19 (13n16) ◽  
pp. 1195-1201
Author(s):  
XIAO-GANG HE
Keyword(s):  
Standard Model ◽  
Symmetry Breaking ◽  
Cosmological Constant ◽  
Spontaneous Symmetry Breaking ◽  
Particle Physics ◽  
Higgs Mass ◽  
Vacuum Energy ◽  
Casimir Energy ◽  
Renormalization Scale ◽  
The Standard Model

Casimir vacuum energy is divergent. It needs to be regularized. The regularization introduces a renormalization scale which may lead to a scale dependent cosmological constant. We show that the requirement of physical cosmological constant is renormalization scale independent provides important constraints on possible particle contents and their masses in particle physics models. In the Standard Model of strong and electroweak interactions, besides the Casimir vacuum energy there is also vacuum energy induced from spontaneous symmetry breaking. The requirement that the total vacuum energy to be scale independent dictates the Higgs mass to be [Formula: see text] where the summation is over fermions and Ni equals to 3 and 1 for quarks and leptons, respectively. The Higgs mass is predicted to be approximately 382 GeV.

scholarly journals Generating Einstein gravity, cosmological constant and Higgs mass from restricted Weyl invariance

2015 ◽  
Vol 30 (30) ◽  
pp. 1550152 ◽  
Author(s):  
Ariel Edery ◽  
Yu Nakayama
Keyword(s):  
Scalar Field ◽  
Cosmological Constant ◽  
Higgs Mass ◽  
Higgs Field ◽  
Higgs Sector ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Invariant Action ◽  
Weyl Invariance ◽  
The Standard Model

Recently, it has been pointed out that dimensionless actions in four-dimensional curved spacetime possess a symmetry which goes beyond scale invariance but is smaller than full Weyl invariance. This symmetry was dubbed restricted Weyl invariance. We show that starting with a restricted Weyl invariant action that includes a Higgs sector with no explicit mass, one can generate the Einstein–Hilbert action with cosmological constant and a Higgs mass. The model also contains an extra massless scalar field which couples to the Higgs field (and gravity). If the coupling of this extra scalar field to the Higgs field is negligibly small, this fixes the coefficient of the nonminimal coupling [Formula: see text] between the Higgs field and gravity. Besides the Higgs sector, all the other fields of the Standard Model can be incorporated into the original restricted Weyl invariant action.

scholarly journals Cosmological constant in coherent quantum gravity

2020 ◽  
Vol 29 (14) ◽  
pp. 2042004
Author(s):  
Craig Hogan
Keyword(s):  
Cosmological Constant ◽  
Vacuum Energy ◽  
Gravitational Effect ◽  
Vacuum State ◽  
Point Particle ◽  
Quantum States ◽  
Energy Flows ◽  
The Standard Model ◽  
Gravitational Drag ◽  
Coherent Quantum

It is argued that quantum states of geometry, like those of particles, should be coherent on light cones of any size. An exact classical solution, the gravitational shock wave of a relativistic point particle, is used to estimate gravitational drag from coherent energy flows, and the expected gravitational effect of virtual transverse vacuum energy fluctuations on surfaces of causal diamonds. It is proposed that the appropriately spacetime-averaged gravitational effect of the Standard Model vacuum state leads to the observed small nonzero value of the cosmological constant, dominated by gravitational drag of virtual gluonic strings at the strong interaction scale.

scholarly journals Higgs flavor phenomenology in a supersymmetric left-right model with parity

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Syuhei Iguro ◽  
Junichiro Kawamura ◽  
Yuji Omura ◽  
Yoshihiro Shigekami
Keyword(s):  
Higgs Mass ◽  
Fine Tuning ◽  
Tree Level ◽  
Supersymmetric Model ◽  
Parameter Region ◽  
Yukawa Couplings ◽  
Lepton Flavor ◽  
Flavor Changing ◽  
Fermion Masses ◽  
The Standard Model

Abstract In this paper, we focus on the supersymmetric model with left-right (LR) symmetry, that is especially proposed in our previous work [1]. In this model, there are four Higgs doublets in order to realize the Standard Model (SM) fermion masses and the Cabibbo-Kobayashi-Maskawa matrix. The heavy Higgs doublets unavoidably have flavor changing couplings to the SM fermions and induce flavor-changing neutral currents at tree level. We study broader parameter space than the previous work with including the renormalization group corrections to the Yukawa couplings between the LR breaking scale, $$ \mathcal{O} $$ O (1013) GeV, and the supersymmetry breaking scales, $$ \mathcal{O} $$ O (100) TeV. The CP violating observable in K–$$ \overline{K} $$ K ¯ mixing, ϵK, strongly constrains the model, so that heavy Higgs mass should be heavier than $$ \mathcal{O} $$ O (100) TeV. We study the lepton flavor violating (LFV) processes setting heavy Higgs masses to be 170 TeV. The branching ratios of μ → 3e and the μ–e conversion can be larger than 10−16 that could be covered by the future experiments. We also study the degree of fine-tuning in the parameter region that predicts testable LFV processes.

scholarly journals CONSTRAINTS ON THE COSMOLOGICAL CONSTANT DUE TO SCALE INVARIANCE

2010 ◽  
Vol 25 (16) ◽  
pp. 1349-1364 ◽  
Author(s):  
PAVAN K. ALURI ◽  
PANKAJ JAIN ◽  
SUBHADIP MITRA ◽  
SUKANTA PANDA ◽  
NAVEEN K. SINGH
Keyword(s):  
Cosmological Constant ◽  
Scale Invariance ◽  
Vacuum Energy ◽  
Higgs Field ◽  
Gauge Fields ◽  
Simple Relationship ◽  
Massless Fermion ◽  
Fermion Fields ◽  
Effective Cosmological Constant ◽  
The Standard Model

We consider the standard model with local scale invariance. The theory shows exact scale invariance of dimensionally regulated action. We show that massless gauge fields, which may be Abelian or non-Abelian, lead to vanishing contribution to the cosmological constant in this theory. This result follows in the quantum theory, to all orders in the gauge couplings. However, we have not considered contributions higher orders in the gravitational coupling. Similarly we also find that massless fermion fields yield null contribution to the cosmological constant. The effective cosmological constant in this theory is nonzero due to the phenomenon of cosmological symmetry breaking, which also gives masses to all the massive fields, besides generating the Planck mass. We find a simple relationship between the curvature scalar and the vacuum value of the Higgs field in the limit when we ignore all other contributions to the energy density besides the vacuum energy.

scholarly journals The fine tuning of the cosmological constant in a conformal model

2015 ◽  
Vol 30 (32) ◽  
pp. 1550171 ◽  
Author(s):  
Pankaj Jain ◽  
Gopal Kashyap ◽  
Subhadip Mitra
Keyword(s):  
Standard Model ◽  
Cosmological Constant ◽  
Conformal Symmetry ◽  
Scalar Fields ◽  
Fine Tuning ◽  
Strongly Coupled ◽  
Conformal Model ◽  
Hidden Sector ◽  
A Value ◽  
The Standard Model

We consider a conformal model involving two real scalar fields in which the conformal symmetry is broken by a soft mechanism and is not anomalous. One of these scalar fields is representative of the standard model Higgs. The model predicts exactly zero cosmological constant. In the simplest version of the model, some of the couplings need to be fine-tuned to very small values. We formulate the problem of fine tuning of these couplings. We argue that the problem arises since we require a soft mechanism to break conformal symmetry. The symmetry breaking is possible only if the scalar fields do not evolve significantly over the time scale of the Universe. Ignoring contributions due to quantum gravity, we present two solutions to this fine tuning problem. We argue that the problem is solved if the classical value of one of the scalar fields is super-Planckian, i.e. takes a value much larger than the Planck mass. The second solution involves introduction of a strongly coupled hidden sector that we call hypercolor. In this case, the conformal invariance is broken dynamically and triggers the breakdown of the electroweak symmetry. We argue that our analysis applies also to the case of the standard model Higgs multiplet.

scholarly journals GRAVITY, COSMOLOGY AND PARTICLE PHYSICS WITHOUT THE COSMOLOGICAL CONSTANT PROBLEM

1998 ◽  
Vol 13 (19) ◽  
pp. 1583-1586 ◽  
Author(s):  
E. I. GUENDELMAN ◽  
A. B. KAGANOVICH
Keyword(s):  
Cosmological Constant ◽  
Particle Physics ◽  
Vacuum Energy ◽  
Vacuum State ◽  
Scalar Fields ◽  
Fine Tuning ◽  
Gauge Fields ◽  
Hierarchy Problem ◽  
Cosmological Constant Problem ◽  
First Order

This letter elucidates recent achievements of the "nongravitating vacuum energy (NGVE) theory" which has the feature that a shift of the Lagrangian density by a constant does not affect dynamics. In the first-order formalism, a constraint appears that enforces the vanishing of the cosmological constant Λ. Standard dynamics of gauge unified theories (including fermions) and their SSB appear if a four-index field strength condensate is present. At the vacuum state, there is exact balance (to zero) of the gauge fields condensate and the original scalar fields potential. As a result it is possible to combine the solution of the Λ problem with inflation and transition to a Λ=0 phase without fine tuning after a reheating period. The model opens new possibilities for a solution of the hierarchy problem.

A COMMON SCENARIO LEADING TO A SMALL VACUUM ENERGY AND STABLE SUPER-MASSIVE PARTICLES

2013 ◽  
Vol 28 (27) ◽  
pp. 1350099 ◽  
Author(s):  
OSVALDO P. SANTILLÁN
Keyword(s):  
Vacuum Energy ◽  
Goldstone Boson ◽  
Heavy Particles ◽  
Hidden Sector ◽  
Mean Lifetime ◽  
The Standard Model ◽  
Present Universe ◽  
Age Of The Universe ◽  
The One ◽  
The Universe

A toy model giving rise to long-lived super-heavy particles and a small vacuum density energy, of the order of the one measured in the present universe, is presented. It consists in a hidden sector, invariant under an SU(2) gauge symmetry, with some masses provided by a specific double Higgs mechanism. It is assumed that the Standard Model particles are also charged under the SU(2) interaction, which is weak enough to allow super-heavy particles with mean lifetime with values larger than the age of the universe. The hidden fermions and the hidden Higgs are super-heavy, which mass values close to the GUT scale. In addition, there is a spontaneously broken U(1) chiral symmetry, giving rise to a pseudoscalar Goldstone boson which we refer as a "hidden axion". The vacuum energy of the universe is identified as the potential energy of this pseudoscalar.

scholarly journals Constraining the Swiss-Cheese IR-Fixed Point Cosmology with Cosmic Expansion

Universe ◽  
2021 ◽  
Vol 7 (8) ◽  
pp. 263
Author(s):  
Ayan Mitra ◽  
Vasilios Zarikas ◽  
Alfio Bonanno ◽  
Michael Good ◽  
Ertan Güdekli
Keyword(s):  
Fixed Point ◽  
Cosmological Constant ◽  
Cosmic Acceleration ◽  
Fine Tuning ◽  
Clusters Of Galaxies ◽  
Swiss Cheese ◽  
Coincidence Problem ◽  
Cosmological Expansion ◽  
Cosmic Evolution ◽  
Previous Assumption

A recent work proposed that the recent cosmic passage to a cosmic acceleration era is the result of the existence of small anti-gravity sources in each galaxy and clusters of galaxies. In particular, a Swiss-cheese cosmology model, which relativistically integrates the contribution of all these anti-gravity sources on a galactic scale has been constructed assuming the presence of an infrared fixed point for a scale dependent cosmological constant. The derived cosmological expansion provides an explanation for both the fine tuning and the coincidence problem. The present work relaxes the previous assumption on the running of the cosmological constant and allows for a generic scaling around the infrared fixed point. Our analysis reveals that, in order to produce a cosmic evolution consistent with the best ΛCDM model, the IR-running of the cosmological constant is consistent with the presence of an IR-fixed point.

scholarly journals The scalar chemical potential in cosmological collider physics

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Arushi Bodas ◽  
Soubhik Kumar ◽  
Raman Sundrum
Keyword(s):  
Particle Production ◽  
Chemical Potential ◽  
Direct Detection ◽  
Heavy Particle ◽  
Scalar Particle ◽  
Energy Scale ◽  
Fine Tuning ◽  
Tree Level ◽  
Heavy Particles ◽  
Non Gaussian

Abstract Non-analyticity in co-moving momenta within the non-Gaussian bispectrum is a distinctive sign of on-shell particle production during inflation, presenting a unique opportunity for the “direct detection” of particles with masses as large as the inflationary Hubble scale (H). However, the strength of such non-analyticity ordinarily drops exponentially by a Boltzmann-like factor as masses exceed H. In this paper, we study an exception provided by a dimension-5 derivative coupling of the inflaton to heavy-particle currents, applying it specifically to the case of two real scalars. The operator has a “chemical potential” form, which harnesses the large kinetic energy scale of the inflaton, $$ {\overset{\cdot }{\phi}}_0^{1/2}\approx 60H $$ ϕ ⋅ 0 1 / 2 ≈ 60 H , to act as an efficient source of scalar particle production. Derivative couplings of inflaton ensure radiative stability of the slow-roll potential, which in turn maintains (approximate) scale-invariance of the inflationary correlations. We show that a signal not suffering Boltzmann suppression can be obtained in the bispectrum with strength fNL ∼ $$ \mathcal{O} $$ O (0.01–10) for an extended range of scalar masses $$ \lesssim {\overset{\cdot }{\phi}}_0^{1/2} $$ ≲ ϕ ⋅ 0 1 / 2 , potentially as high as 1015 GeV, within the sensitivity of upcoming LSS and more futuristic 21-cm experiments. The mechanism does not invoke any particular fine-tuning of parameters or breakdown of perturbation-theoretic control. The leading contribution appears at tree-level, which makes the calculation analytically tractable and removes the loop-suppression as compared to earlier chemical potential studies of non-zero spins. The steady particle production allows us to infer the effective mass of the heavy particles and the chemical potential from the variation in bispectrum oscillations as a function of co-moving momenta. Our analysis sets the stage for generalization to heavy bosons with non-zero spin.

Sign in / Sign up

Export Citation Format

Share Document