scholarly journals Lowering the scale of Pati-Salam breaking through seesaw mixing

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Matthew J. Dolan ◽  
Tomasz P. Dutka ◽  
Raymond R. Volkas
Keyword(s):  
Degrees Of Freedom ◽  
Tree Level ◽  
Charged Current ◽  
Meson Decay ◽  
Neutrino Masses ◽  
Down Quark ◽  
The Standard Model ◽  
Decay Widths ◽  
Left And Right ◽  
Charged Leptons

Abstract We analyse the experimental limits on the breaking scale of Pati-Salam extensions of the Standard Model. These arise from the experimental limits on rare-meson decay processes mediated at tree-level by the vector leptoquark in the model. This leptoquark ordinarily couples to both left- and right-handed SM fermions and therefore the meson decays do not experience a helicity suppression. We find that the current limits vary from $$ \mathcal{O} $$ O (80–2500) TeV depending on the choice of matrix structure appearing in the relevant three-generational charged-current interactions. We extensively analyse scenarios where additional fermionic degrees of freedom are introduced, transforming as complete Pati-Salam multiplets. These can lower the scales of Pati-Salam breaking through mass-mixing within the charged-lepton and down-quark sectors, leading to a helicity suppression of the meson decay widths which constrain Pati-Salam breaking. We find four multiplets with varying degrees of viability for this purpose: an SU(2)L/R bidoublet, a pair of SU(4) decuplets and either an SU(2)L or SU(2)R triplet all of which contain heavy exotic versions of the SM charged leptons. We find that the Pati-Salam limits can be as low as $$ \mathcal{O} $$ O (5–150) TeV with the addition of these four multiplets. We also identify an interesting possible connection between the smallness of the neutrino masses and a helicity suppression of the Pati-Salam limits for three of the four multiplets.

scholarly journals Supersymmetric U(1)Y′⊗ U(1)B−L extension of the Standard Model

2017 ◽  
Vol 32 (16) ◽  
pp. 1750093 ◽  
Author(s):  
J. C. Montero ◽  
V. Pleitez ◽  
B. L. Sánchez-Vega ◽  
M. C. Rodriguez
Keyword(s):  
Gauge Symmetry ◽  
Mass Spectra ◽  
Tree Level ◽  
Neutrino Masses ◽  
Type I ◽  
Seesaw Mechanism ◽  
Active Neutrino ◽  
Supersymmetric Version ◽  
Fermion Masses ◽  
The Standard Model

We build a supersymmetric version with [Formula: see text] gauge symmetry, where [Formula: see text] is a new charge and [Formula: see text] and [Formula: see text] are the usual baryonic and leptonic numbers. The model has three right-handed neutrinos with identical [Formula: see text] charges, and can accommodate all fermion masses at the tree level. In particular, the type I seesaw mechanism is implemented for the generation of the active neutrino masses. We obtain the mass spectra of all sectors and for the scalar one we also give the flat directions allowed by the model.

AN SU(2)L×U(1)L×U(1)R MODEL WITH FINITE DIRAC NEUTRINO MASSES

1993 ◽  
Vol 08 (10) ◽  
pp. 895-902 ◽  
Author(s):  
SUBHASH RAJPOOT
Keyword(s):  
Standard Model ◽  
Discrete Symmetry ◽  
Lepton Number ◽  
Tree Level ◽  
Neutrino Masses ◽  
Charged Scalar ◽  
Dirac Neutrino ◽  
Left Handed ◽  
The Standard Model ◽  
The One

An SU(2)L×U(1)L×U(1)R model of electroweak interactions is presented in which the conventional fermions of the standard model are left-handed doublets under SU(2)L× U(1)L and are right-handed singlets under U(1) R . The triangle anomalies are canceled by adding vector-like singlet fermions. Neutrinos are massless at the tree level due to a discrete symmetry and acquire tiny finite masses at the one-loop level due to the exchange of two charged scalar singlets. The singlet scalars carry two units of lepton number.

QUASI SUPERSYMMETRY WITHIN THE STANDARD MODEL AND HIGGS MASS

1999 ◽  
Vol 14 (35) ◽  
pp. 2447-2452
Author(s):  
B. B. DEO ◽  
L. P. SINGH
Keyword(s):  
Standard Model ◽  
Top Quark ◽  
Degrees Of Freedom ◽  
Higgs Mass ◽  
Higgs Bosons ◽  
Tree Level ◽  
Mass Relation ◽  
The Standard Model ◽  
A Charge ◽  
Higgs Fields

The 12 bosonic degrees of freedom of the standard model (SM) are exactly matched by fermionic degrees of freedom of a single colored quark, e.g. top. Indeed, we construct a charge involving top-quark, gauge and Higgs fields which satisfy usual supersymmetry algebra. The colored quark states behave like the superpartners of gauge and Higgs bosons and vice versa. When this SUSY is broken, a mass relation must be satisfied at the tree level from which the mass of the Higgs is predicted to be 300.5±11 GeV.

scholarly journals Higgs inflation, vacuum stability, and leptogenesis

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
Neil D. Barrie ◽  
Akio Sugamoto ◽  
Tatsu Takeuchi ◽  
Kimiko Yamashita
Keyword(s):  
Degrees Of Freedom ◽  
Planck Scale ◽  
Neutrino Masses ◽  
Minimal Coupling ◽  
Parameter Region ◽  
Complex Scalar ◽  
Vacuum Stability ◽  
Higgs Vacuum ◽  
The Standard Model ◽  
Complex Scalar Field

Abstract We consider the introduction of a complex scalar field carrying a global lepton number charge to the Standard Model and the Higgs inflation framework. The conditions are investigated under which this model can simultaneously ensure Higgs vacuum stability up to the Planck scale, successful inflation, non-thermal Leptogenesis via the pendulum mechanism, and light neutrino masses. These can be simultaneously achieved when the scalar lepton is minimally coupled to gravity, that is, when standard Higgs inflation and reheating proceed without the interference of the additional scalar degrees of freedom. If the scalar lepton also has a non-minimal coupling to gravity, a multi-field inflation scenario is induced, with interesting interplay between the successful inflation constraints and those from vacuum stability and Leptogenesis. The parameter region that can simultaneously achieve the above goals is explored.

scholarly journals Extending low energy effective field theory with a complete set of dimension-7 operators

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
Yi Liao ◽  
Xiao-Dong Ma ◽  
Quan-Yu Wang
Keyword(s):  
Field Theory ◽  
Standard Model ◽  
Cross Sections ◽  
Effective Field Theory ◽  
Degrees Of Freedom ◽  
Independent Set ◽  
Effective Field ◽  
Low Energy ◽  
Tree Level ◽  
The Standard Model

Abstract We present a complete and independent set of dimension-7 operators in the low energy effective field theory (LEFT) where the dynamical degrees of freedom are the standard model five quarks and all of the neutral and charged leptons. All operators are non-Hermitian and are classified according to their baryon (∆B) and lepton (∆L) numbers violated. Including Hermitian-conjugated operators, there are in total 3168, 750, 588, 712 operators with (∆B, ∆L) = (0, 0), (0, ±2), (±1, ∓1), (±1, ±1) respectively. We perform the tree-level matching with the standard model effective field theory (SMEFT) up to dimension-7 (dim-7) operators in both LEFT and SMEFT. As a phenomenological application we study the effective neutrino-photon interactions due to dim-7 lepton number violating operators that are induced and much enhanced at one loop from dim-6 operators that in turn are matched from dim-7 SMEFT operators. We compare various neutrino-photon scattering cross sections with their counterparts in the standard model and highlight the new features. Finally, we illustrate how these effective interactions could arise from ultraviolet completion.

scholarly journals Light neutrino masses from gravitational condensation: the Schwinger–Dyson approach

2021 ◽  
Vol 81 (6) ◽  
Author(s):  
Gabriela Barenboim ◽  
Jessica Turner ◽  
Ye-Ling Zhou
Keyword(s):  
Standard Model ◽  
Symmetry Breaking ◽  
Degrees Of Freedom ◽  
Chiral Symmetry Breaking ◽  
Planck Scale ◽  
Neutrino Masses ◽  
Beyond The Standard Model ◽  
Standard Model Particle ◽  
Particle Content ◽  
The Standard Model

AbstractIn this work we demonstrate that non-zero neutrino masses can be generated from gravitational interactions. We solve the Schwinger–Dyson equations to find a non-trivial vacuum thereby determining the neutrino condensate scale and the number of new particle degrees of freedom required for gravitationally induced dynamical chiral symmetry breaking. We show for minimal beyond the Standard Model particle content, the scale of the condensation occurs close to the Planck scale.

scholarly journals Neutrino masses in the SU(4)L ⊗ U(1)X electroweak extension of the Standard Model

2016 ◽  
Vol 31 (25) ◽  
pp. 1650142 ◽  
Author(s):  
Guillermo Palacio
Keyword(s):  
Standard Model ◽  
Neutrino Mass ◽  
Tree Level ◽  
Neutrino Masses ◽  
Particle Content ◽  
Mass Generation ◽  
The Standard Model ◽  
Neutrino Mass Generation ◽  
Effective Operators ◽  
Family Models

We study the neutrino mass generation in the [Formula: see text] electroweak extension of the Standard Model by considering nonrenormalizable dimension 5 effective operators. It is shown that there exist two topologies for the realizations of such an operator at the tree-level and for one of the three-family models the neutrino phenomenology is explored after extending its particle content with an [Formula: see text] fermion singlet and a scalar decuplet. Constraints in the available parameters space of the model are partially discussed.

scholarly journals Charming ALPs

2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
Adrian Carmona ◽  
Christiane Scherb ◽  
Pedro Schwaller
Keyword(s):  
Ultra Violet ◽  
New Physics ◽  
Low Energy ◽  
Effective Theory ◽  
Tree Level ◽  
Meson Decay ◽  
Fixed Target ◽  
The Standard Model ◽  
Model Independent ◽  
Key Features

Abstract Axion-like particles (ALPs) are ubiquitous in models of new physics explaining some of the most pressing puzzles of the Standard Model. However, until relatively recently, little attention has been paid to its interplay with flavour. In this work, we study in detail the phenomenology of ALPs that exclusively interact with up-type quarks at the tree-level, which arise in some well-motivated ultra-violet completions such as QCD-like dark sectors or Froggatt-Nielsen type models of flavour. Our study is performed in the low-energy effective theory to highlight the key features of these scenarios in a model independent way. We derive all the existing constraints on these models and demonstrate how upcoming experiments at fixed-target facilities and the LHC can probe regions of the parameter space which are currently not excluded by cosmological and astrophysical bounds. We also emphasize how a future measurement of the currently unavailable meson decay D → π + invisible could complement these upcoming searches.

scholarly journals Vacuum stability in inert higgs doublet model with right-handed neutrinos

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
Shilpa Jangid ◽  
Priyotosh Bandyopadhyay ◽  
P.S. Bhupal Dev ◽  
Arjun Kumar
Keyword(s):  
Higgs Doublet ◽  
Tree Level ◽  
Dark Matter Candidate ◽  
Neutrino Masses ◽  
Vacuum Stability ◽  
Seesaw Mechanism ◽  
Yukawa Couplings ◽  
The Standard Model ◽  
Doublet Model ◽  
The Stability

Abstract We analyze the vacuum stability in the inert Higgs doublet extension of the Standard Model (SM), augmented by right-handed neutrinos (RHNs) to explain neutrino masses at tree level by the seesaw mechanism. We make a comparative study of the high- and low-scale seesaw scenarios and the effect of the Dirac neutrino Yukawa couplings on the stability of the Higgs potential. Bounds on the scalar quartic couplings and Dirac Yukawa couplings are obtained from vacuum stability and perturbativity considerations. These bounds are found to be relevant only for low-scale seesaw scenarios with relatively large Yukawa couplings. The regions corresponding to stability, metastability and instability of the electroweak vacuum are identified. These theoretical constraints give a very predictive parameter space for the couplings and masses of the new scalars and RHNs which can be tested at the LHC and future colliders. The lightest non-SM neutral CP-even/odd scalar can be a good dark matter candidate and the corresponding collider signatures are also predicted for the model.

scholarly journals ALTERNATIVE IMPLEMENTATION OF THE HIGGS BOSON

2011 ◽  
Vol 26 (07) ◽  
pp. 461-467
Author(s):  
ROBERT FOOT ◽  
ARCHIL KOBAKHIDZE
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Gauge Invariance ◽  
Degrees Of Freedom ◽  
Energy Scale ◽  
Tree Level ◽  
Radiative Corrections ◽  
Gauge Bosons ◽  
The Standard Model ◽  
Low Energies

We discuss an alternative implementation of the Higgs boson within the Standard Model which is possible if the renormalizability condition is relaxed. Namely, at energy scale Λ the Higgs boson interacts at tree-level only with matter fermions, while the full gauge invariance is still maintained. The interactions with the electroweak gauge bosons are induced at low energies through the radiative corrections. In this scenario the Higgs boson can be arbitrarily heavy, interacting with the Standard Model fields arbitrarily weakly. No violation of unitarity in the scattering of longitudinal electroweak bosons occurs, since they become unphysical degrees of freedom at energies Λ ~ TeV.

Sign in / Sign up

Export Citation Format

Share Document