scholarly journals Perturbative unitarity in quasi-single field inflation

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Suro Kim ◽  
Toshifumi Noumi ◽  
Keito Takeuchi ◽  
Siyi Zhou
Keyword(s):  
Quantum Gravity ◽  
Parameter Space ◽  
High Energy ◽  
New Physics ◽  
Energy Scale ◽  
Effective Theory ◽  
Massive Scalar ◽  
High Energy Scale ◽  
Single Field ◽  
High Energy Scattering

Abstract We study implications of perturbative unitarity for quasi-single field inflation with the inflaton and one massive scalar. Analyzing high energy scattering, we show that non-Gaussianities with |fNL| ≳ 1 cannot be realized without turning on interactions which violate unitarity at a high energy scale. Then, we provide a relation between fNL and the scale of new physics that is required for UV completion. In particular we find that for the Hubble scale H ≳ × 109 GeV, Planck suppressed operators can easily generate too large non-Gaussanities and so it is hard to realize successful quasi-single field inflation without introducing a mechanism to suppress quantum gravity corrections. Also we generalize the analysis to the regime where the isocurvature mode is heavy and the inflationary dynamics is captured by the inflaton effective theory. Requiring perturbative unitarity of the two-scalar UV models with the inflaton and one heavy scalar, we clarify the parameter space of the P(X, ϕ) model which is UV completable by a single heavy scalar.

scholarly journals Particle–Antiparticle Asymmetry in Relativistic Deformed Kinematics

Symmetry ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1266
Author(s):  
José Manuel Carmona ◽  
José Luis Cortés ◽  
José Javier Relancio
Keyword(s):  
Quantum Gravity ◽  
Particle System ◽  
High Energy ◽  
Energy Scale ◽  
Muon Decay ◽  
Total Momentum ◽  
Gravity Theory ◽  
Residual Effects ◽  
Cpt Symmetry ◽  
High Energy Scale

Relativistic deformed kinematics are usually considered a way to capture the residual effects of a fundamental quantum gravity theory. These kinematics present a non-commutative addition law for the momenta so that the total momentum of a multi-particle system depends on the specific ordering in which the momenta are composed. We explore in the present work how this property may be used to generate an asymmetry between particles and antiparticles through a particular ordering prescription, resulting in a violation of CPT symmetry. We study its consequences for muon decay, obtaining a difference in the lifetimes of the particle and the antiparticle as a function of the new high-energy scale, parameterizing such relativistic deformed kinematics.

scholarly journals Lorentz Violation, Möller Scattering, and Finite Temperature

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Alesandro F. Santos ◽  
Faqir C. Khanna
Keyword(s):  
Finite Temperature ◽  
Planck Scale ◽  
Lorentz Violation ◽  
High Energy ◽  
New Physics ◽  
Energy Scale ◽  
Moller Scattering ◽  
Thermo Field Dynamics ◽  
Very High Energy ◽  
High Energy Scale

Lorentz and CPT symmetries may be violated in new physics that emerges at very high energy scale, that is, at the Planck scale. The differential cross section of the Möller scattering due to Lorentz violation at finite temperature is calculated. Lorentz-violating effects emerge from an interaction vertex due to a CPT-odd nonminimal coupling in the covariant derivative. The finite temperature effects are determined using the Thermo Field Dynamics (TFD) formalism.

scholarly journals RENORMALIZATION GROUP EVOLUTION OF NEUTRINO MASSES AND MIXING IN SEESAW MODELS

2010 ◽  
Vol 25 (23) ◽  
pp. 4339-4384 ◽  
Author(s):  
SHAMAYITA RAY
Keyword(s):  
Renormalization Group ◽  
High Energy ◽  
Energy Scale ◽  
Low Energy ◽  
Effective Theory ◽  
Neutrino Masses ◽  
Mixing Parameters ◽  
Group Evolution ◽  
High Energy Scale ◽  
The Masses

We consider different extensions of the Standard Model which can give rise to the small active neutrino masses through seesaw mechanisms, and their mixing. These tiny neutrino masses are generated at some high energy scale by the heavy seesaw fields which then get sequentially decoupled to give an effective dimension-5 operator at the low energy. The renormalization group evolution of the masses and the mixing parameters of the three active neutrinos in the high energy as well as the low energy effective theory is reviewed in this paper.

scholarly journals The contribution of effective quantum gravity to the high energy scattering in the framework of modified perturbation theory and one loop approximation

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
Nguyen Suan Han ◽  
Do Thu Ha ◽  
Nguyen Nhu Xuan
Keyword(s):  
Perturbation Theory ◽  
Quantum Gravity ◽  
Scattering Amplitude ◽  
High Energy ◽  
Effective Theory ◽  
Potential Equation ◽  
Scalar Particles ◽  
Loop Approximation ◽  
The One ◽  
High Energy Scattering

Abstract The asymptotic behavior of the scattering amplitude for two scalar particles at high energies with fixed momentum transfers is studied. The study is done within the effective theory of quantum gravity based on quasi-potential equation. By using the modified perturbation theory, a systematic method is developed to find the leading eikonal scattering amplitudes together with corrections to them in the one-loop gravitational approximation. The relation is established and discussed between the solutions obtained by means of the operator and functional approaches applied to quasi-potential equation. The first non-leading corrections to the leading eikonal amplitude are found.

scholarly journals Search for Anomalous Quartic ZZγγ Couplings in Photon-Photon Collisions

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
M. Köksal ◽  
V. Arı ◽  
A. Senol
Keyword(s):  
Linear Collider ◽  
Center Of Mass ◽  
High Energy ◽  
New Physics ◽  
Energy Scale ◽  
Mass Energy ◽  
Abelian Gauge ◽  
Center Of Mass Energy ◽  
High Energy Scale ◽  
Integrated Luminosity

The self-couplings of the electroweak gauge bosons are completely specified by the non-Abelian gauge nature of the Standard Model (SM). The direct study of these couplings provides a significant opportunity to test the validity of the SM and the existence of new physics beyond the SM up to the high energy scale. For this reason, we investigate the potential of the processes γγ→ZZ, e-γ→e-γ⁎γ→e-ZZ,  and e+e-→e+γ⁎γ⁎e-→e+ZZe- to examine the anomalous quartic couplings of ZZγγ vertex at the Compact Linear Collider (CLIC) with center-of-mass energy 3 TeV. We calculate 95% confidence level sensitivities on the dimension-8 parameters with various values of the integrated luminosity. We show that the best bounds on the anomalous fM2/Λ4, fM3/Λ4, fT0/Λ4, and fT9/Λ4 couplings arising from γγ→ZZ process among those three processes at center-of-mass energy of 3 TeV and integrated luminosity of Lint=2000 fb−1 are found to be [-3.30;3.30]×10-3 TeV−4, [-1.20;1.20]×10-2 TeV−4, [-3.40;3.40]×10-3 TeV−4, and [-1.80;1.80]×10-3 TeV−4, respectively.

scholarly journals Hilbert series for leptonic flavor invariants in the minimal seesaw model

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Bingrong Yu ◽  
Shun Zhou
Keyword(s):  
Hilbert Series ◽  
Rational Functions ◽  
High Energy ◽  
Energy Scale ◽  
Effective Theory ◽  
Practical Applications ◽  
Phenomenological Studies ◽  
Sufficient And Necessary Conditions ◽  
High Energy Scale ◽  
First Time

Abstract In this paper, we examine the leptonic flavor invariants in the minimal see-saw model (MSM), in which only two right-handed neutrino singlets are added into the Standard Model in order to accommodate tiny neutrino masses and explain cosmological matter-antimatter asymmetry via leptogenesis mechanism. For the first time, we calculate the Hilbert series (HS) for the leptonic flavor invariants in the MSM. With the HS we demonstrate that there are totally 38 basic flavor invariants, among which 18 invariants are CP-odd and the others are CP-even. Moreover, we explicitly construct these basic invariants, and any other flavor invariants in the MSM can be decomposed into the polynomials of them. Interestingly, we find that any flavor invariants in the effective theory at the low-energy scale can be expressed as rational functions of those in the full MSM at the high-energy scale. Practical applications to the phenomenological studies of the MSM, such as the sufficient and necessary conditions for CP conservation and CP asymmetries in leptogenesis, are also briefly discussed.

scholarly journals The low-energy effective theory of axions and ALPs

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Martin Bauer ◽  
Matthias Neubert ◽  
Sophie Renner ◽  
Marvin Schnubel ◽  
Andrea Thamm
Keyword(s):  
High Energy ◽  
New Physics ◽  
Mass Scale ◽  
Low Energy ◽  
Effective Theory ◽  
Loop Order ◽  
Flavor Changing ◽  
Effective Lagrangian ◽  
Anomalous Dimensions ◽  
Pseudoscalar Mesons

Abstract Axions and axion-like particles (ALPs) are well-motivated low-energy relics of high-energy extensions of the Standard Model, which interact with the known particles through higher-dimensional operators suppressed by the mass scale Λ of the new-physics sector. Starting from the most general dimension-5 interactions, we discuss in detail the evolution of the ALP couplings from the new-physics scale to energies at and below the scale of electroweak symmetry breaking. We derive the relevant anomalous dimensions at two-loop order in gauge couplings and one-loop order in Yukawa interactions, carefully considering the treatment of a redundant operator involving an ALP coupling to the Higgs current. We account for one-loop (and partially two-loop) matching contributions at the weak scale, including in particular flavor-changing effects. The relations between different equivalent forms of the effective Lagrangian are discussed in detail. We also construct the effective chiral Lagrangian for an ALP interacting with photons and light pseudoscalar mesons, pointing out important differences with the corresponding Lagrangian for the QCD axion.

scholarly journals Flavour Anomalies in a U(1) SUSY Extension of the SM

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 191
Author(s):  
Alexander Bednyakov ◽  
Alfiia Mukhaeva
Keyword(s):  
Standard Model ◽  
Parameter Space ◽  
Gauge Boson ◽  
New Physics ◽  
Low Energy ◽  
Effective Theory ◽  
The Standard Model ◽  
Meson Mixing ◽  
Additional Anomaly ◽  
Lepton Flavour

Flavour anomalies have attracted a lot of attention over recent years as they provide unique hints for possible New Physics. Here, we consider a supersymmetric (SUSY) extension of the Standard Model (SM) with an additional anomaly-free gauge U(1) group. The key feature of our model is the particular choice of non-universal charges to the gauge boson Z′, which not only allows a relaxation of the flavour discrepancies but, contrary to previous studies, can reproduce the SM mixing matrices both in the quark and lepton sectors. We pay special attention to the latter and explicitly enumerate all parameters relevant for our calculation in the low-energy effective theory. We find regions in the parameter space that satisfy experimental constraints on meson mixing and LHC Z′ searches and can alleviate the flavour anomalies. In addition, we also discuss the predictions for lepton-flavour violating decays B+→K+μτ and B+→K+eτ.

scholarly journals Beginning of Universe through large field hybrid inflation

2015 ◽  
Vol 30 (21) ◽  
pp. 1550106 ◽  
Author(s):  
Tatsuo Kobayashi ◽  
Osamu Seto
Keyword(s):  
Gravitational Wave ◽  
Early Universe ◽  
High Energy ◽  
Wave Mode ◽  
Energy Scale ◽  
Large Field ◽  
Tensor Perturbation ◽  
Expectation Value ◽  
Hybrid Inflation ◽  
High Energy Scale

Recent detection of B-mode polarization induced from tensor perturbations by the BICEP2 experiment implies the so-called large field inflation, where an inflaton field takes super-Planckian expectation value during inflation, at a high energy scale. We show however, if another inflation follows hybrid inflation, the hybrid inflation can generate a large tensor perturbation with not super-Planckian but Planckian field value. This scenario would relax the tension between BICEP2 and Planck concerning the tensor-to-scalar ratio, because a negative large running can also be obtained for a certain number of e-fold of the hybrid inflation. A natural interpretation of a large gravitational wave mode with or without the scalar spectral running might be multiple inflation in the early Universe.

Sign in / Sign up

Export Citation Format

Share Document