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 A simple assessment on the hierarchy problem

2016 ◽  
Vol 13 (06) ◽  
pp. 1650068 ◽  
Author(s):  
Luca Fabbri
Keyword(s):  
Standard Model ◽  
Cosmological Constant ◽  
Scalar Fields ◽  
Hierarchy Problem ◽  
Cosmological Constant Problem ◽  
The Standard Model

We consider the simplest extension of the standard model, where torsion couples to spinor as well as the scalar fields, and in which the cosmological constant problem is solved.

scholarly journals BOSONIC SEESAW AND A SOLUTION TO THE μ PROBLEM IN THE UNPARTICLE PHYSICS

2010 ◽  
Vol 25 (09) ◽  
pp. 691-701
Author(s):  
TATSURU KIKUCHI
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Symmetry Breaking ◽  
Conformal Symmetry ◽  
New Physics ◽  
Electroweak Symmetry Breaking ◽  
Effective Theory ◽  
Electroweak Symmetry ◽  
Hidden Sector ◽  
The Standard Model

Recently, conceptually new physics beyond the Standard Model has been proposed by Georgi, where a new physics sector becomes conformal and provides "unparticle" which couples to the Standard Model sector through higher dimensional operators in low energy effective theory. Among several possibilities, we focus on operators involving the unparticle and Higgs boson. Once the Higgs develops the vacuum expectation value (VEV), the conformal symmetry is broken and as a result, the mixing between the unparticle and the Higgs boson emerges. In the former part of this paper, we consider a natural realization of bosonic seesaw in the context of unparticle physics. In this framework, the negative mass squared or the electroweak symmetry breaking vacuum is achieved as a result of mass matrix diagonalization. So, the bosonic seesaw mechanism for the electroweak symmetry breaking can naturally be understood in the framework of unparticle physics. In the latter part of this paper, we consider the unparticle as a hidden sector of supersymmetry breaking, and give some phenomenological consequences of this scenario. The result shows that there is a possibility for the unparticle as a hidden sector in SUSY breaking sector, and can provide a solution to the μ problem in SUSY models.

scholarly journals Standard model from a supergravity model with a naturally small cosmological constant

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Shing Yan Li ◽  
Yu-Cheng Qiu ◽  
S.-H. Henry Tye
Keyword(s):  
String Theory ◽  
Standard Model ◽  
Cosmological Constant ◽  
Supersymmetry Breaking ◽  
Supersymmetric Standard Model ◽  
Degrees Of Freedom ◽  
Interaction Terms ◽  
Supersymmetric Version ◽  
The Standard Model ◽  
Linear Version

Abstract Guided by the naturalness criterion for an exponentially small cosmological constant, we present a string theory motivated 4-dimensional $$ \mathcal{N} $$ N = 1 non-linear supergravity model (or its linear version with a nilpotent superfield) with spontaneous supersymmetry breaking. The model encompasses the minimal supersymmetric standard model, the racetrack Kähler uplift, and the KKLT anti-D3-branes, and use the nilpotent superfield to project out the undesirable interaction terms as well as the unwanted degrees of freedom to end up with the standard model (not the supersymmetric version) of strong and electroweak interactions.

scholarly journals DARK MATTER, AND ITS DARKNESS

2006 ◽  
Vol 15 (12) ◽  
pp. 2267-2278 ◽  
Author(s):  
D. V. AHLUWALIA-KHALILOVA
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Cosmological Constant ◽  
Model Material ◽  
Representation Space ◽  
Spatial Curvature ◽  
The Standard Model ◽  
General Relativistic ◽  
Relativistic Description ◽  
Friedmann Robertson Walker

Assuming the validity of the general relativistic description of gravitation on astrophysical and cosmological length scales, we analytically infer that the Friedmann–Robertson–Walker cosmology with Einsteinian cosmological constant, and a vanishing spatial curvature constant, unambiguously requires a significant amount of dark matter. This requirement is consistent with other indications for dark matter. The same space–time symmetries that underlie the freely falling frames of Einsteinian gravity also provide symmetries which, for the spin one half representation space, furnish a novel construct that carries extremely limited interactions with respect to the terrestrial detectors made of the standard model material. Both the "luminous" and "dark" matter turn out to be residents of the same representation space but they derive their respective "luminosity" and "darkness" from either belonging to the sector with (CPT)2 = +𝟙, or to the sector with (CPT)2 = -𝟙.

scholarly journals Conformal symmetry and the Standard Model

2007 ◽  
Vol 648 (4) ◽  
pp. 312-317 ◽  
Author(s):  
Krzysztof A. Meissner ◽  
Hermann Nicolai
Keyword(s):  
Standard Model ◽  
Conformal Symmetry ◽  
The Standard Model

scholarly journals Exploration of Extended Higgs Sectors with Run-2 Proton–Proton Collision Data at the LHC

Symmetry ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2144
Author(s):  
Arnaud Ferrari ◽  
Nikolaos Rompotis
Keyword(s):  
Standard Model ◽  
Higgs Sector ◽  
Scalar Fields ◽  
Higgs Bosons ◽  
Proton Collision ◽  
Complex Scalar ◽  
Proton Proton ◽  
The Standard Model ◽  
Extended Higgs Sectors ◽  
Proton Proton Collision

One doublet of complex scalar fields is the minimal content of the Higgs sector in order to achieve spontaneous electroweak symmetry breaking and, in turn, to generate the masses of fundamental particles in the Standard Model. However, several theories beyond the Standard Model predict a nonminimal Higgs sector and introduce additional singlets, doublets or even higher-order weak isospin representations, thereby yielding additional Higgs bosons. With its high proton–proton collision energy (13 TeV during Run-2), the Large Hadron Collider opens a new window towards the exploration of extended Higgs sectors. This review article summarises the current state-of-the-art experimental results recently obtained in searches for new neutral and charged Higgs bosons with a partial or full Run-2 dataset.

SCALE GAUGE SYMMETRY AND THE STANDARD MODEL

1990 ◽  
Vol 05 (22) ◽  
pp. 4225-4240 ◽  
Author(s):  
J. SOLÀ
Keyword(s):  
Gauge Symmetry ◽  
Standard Model ◽  
Cosmological Constant ◽  
Minimal Model ◽  
Harmonic Map ◽  
Strong Interactions ◽  
Cosmological Constant Problem ◽  
The Standard Model ◽  
Conformal Gauge ◽  
Scalar Sector

We speculate on a version of the "standard" model of the electroweak and strong interactions coupled to gravity and equipped with a spontaneously broken, anomalous, conformal gauge symmetry. The scalar sector is virtually absent in the minimal model but in the general case it shows up in the form of a nonlinear harmonic map Lagrangian. A Euclidean approach to the cosmological constant problem is also addressed in this framework.

scholarly journals A bottom-up approach to fermion mass hierarchy: a case with vector-like fermions

2020 ◽  
Vol 2020 (4) ◽  
Author(s):  
Yoshiharu Kawamura
Keyword(s):  
Standard Model ◽  
Yukawa Coupling ◽  
High Energy ◽  
Fine Tuning ◽  
Fermion Mass ◽  
Extended Model ◽  
Mass Hierarchy ◽  
Bottom Up ◽  
Existence Proofs ◽  
The Standard Model

Abstract We propose a bottom-up approach in which a structure of high-energy physics is explored by accumulating existence proofs and/or no-go theorems in the standard model or its extension. As an illustration, we study fermion mass hierarchies based on an extension of the standard model with vector-like fermions. It is shown that the magnitude of elements of Yukawa coupling matrices can become $O(1)$ and a Yukawa coupling unification can be realized in a theory beyond the extended model, if vector-like fermions mix with three families. In this case, small Yukawa couplings in the standard model can be highly sensitive to a small variation of matrix elements, and it seems that the mass hierarchy occurs as a result of fine tuning.

scholarly journals Rb, Rc and New Physics: An Updated Model Independent Analysis

1997 ◽  
Vol 12 (04) ◽  
pp. 723-742 ◽  
Author(s):  
P. Bamert
Keyword(s):  
Standard Model ◽  
Neutral Current ◽  
New Physics ◽  
Low Energy ◽  
Coupling Constant ◽  
A Value ◽  
Independent Analysis ◽  
The Standard Model ◽  
Necessary And Sufficient ◽  
Do So

We analyze LEP and SLC data from the 1995 Summer Conferences as well as from low energy neutral current experiments for signals of new physics. The reasons for doing this are twofold: first to explain the deviations from the Standard Model observed in Rb and Rc and second to constrain nonstandard contributions to couplings of the Z0 boson to all fermions and to the oblique parameters. We do so by comparing the data with the Standard Model as well as with a number of test hypotheses concerning the nature of the new physics. These include nonstandard [Formula: see text]-, [Formula: see text]- and [Formula: see text]-couplings as well as the couplings of the Z0 to fermions of the entire first, second and third generations and universal corrections to all up- and down-type quark couplings (as can arise see for example in Z' mixing models). We find that nonstandard [Formula: see text] couplings are both necessary and sufficient to explain the data and in particular the Rb anomaly. It is not possible to explain Rb, Rc and a value of the strong coupling constant consistent with low energy determinations invoking only nonstandard [Formula: see text]- and [Formula: see text]-couplings. To do so one has to have also new physics contributions to the [Formula: see text] or universal corrections to all [Formula: see text] couplings.

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.

Sign in / Sign up

Export Citation Format

Share Document