scholarly journals Probing leptogenesis and pre-BBN universe with gravitational waves spectral shapes

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
Rome Samanta ◽  
Satyabrata Datta
Keyword(s):  
Equation Of State ◽  
Gravitational Waves ◽  
Cosmic Strings ◽  
Gravitational Interaction ◽  
Big Bang ◽  
Double Beta Decay ◽  
Neutrino Masses ◽  
Seesaw Model ◽  
String Loop ◽  
The Right

Abstract On the frequency-amplitude plane, Gravitational Waves (GWs) from cosmic strings show a flat plateau at higher frequencies due to the string loop dynamics in standard radiation dominated post-inflationary epoch. The spectrum may show an abrupt upward or a downward trend beyond a turning point frequency f*, if the primordial dark age prior to the Big Bang Nucleosynthesis (BBN), exhibits non-standard cosmic histories. We argue that such a spectral break followed by a rising GW amplitude which is a consequence of a post-inflationary equation of state (ω > 1/3) stiffer than the radiation (ω = 1/3), could also be a strong hint of a leptogenesis in the seesaw model of neutrino masses. Dynamical generation of the right handed (RH) neutrino masses by a gauged U(1) symmetry breaking leads to the formation of a network of cosmic strings which emits stochastic GWs. A gravitational interaction of the lepton current by an operator of the form ∂μRjμ — which can be generated in the seesaw model at the two-loop level through RH neutrino mediation, naturally seeks a stiffer equation of state to efficiently produce baryon asymmetry proportional to 1 − 3ω. We discuss how GWs with reasonably strong amplitudes complemented by a neutrino-less double beta decay signal could probe the onset of the most recent radiation domination and lightest RH neutrino mass at the intermediate scales.

Whispers from the Big Bang

2019 ◽  
pp. 581-624
Author(s):  
Nils Andersson
Keyword(s):  
Phase Transitions ◽  
Gravitational Waves ◽  
Cosmic Strings ◽  
Big Bang ◽  
Cosmological Redshift ◽  
Pulsar Timing ◽  
The Standard Model ◽  
Binary Mergers ◽  
Stochastic Backgrounds ◽  
The Big Bang

This chapter discusses gravitational waves in the context of cosmology, starting from a summary of the standard model for cosmology—Lambda CDM. The cosmological redshift is introduced and different ways to measure distances in an expanding universe are considered, including the idea of using binary mergers as standard ‘sirens’. Different stochastic backgrounds are considered and the use of pulsar timing arrays to detect gravitational waves is introduced. The chapter ends with a discussion of cosmological backgrounds due to quantum fluctuations, phase transitions, and cosmic strings

scholarly journals Prospects of gravitational waves in the minimal left-right symmetric model

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Mingqiu Li ◽  
Qi-Shu Yan ◽  
Yongchao Zhang ◽  
Zhijie Zhao
Keyword(s):  
Phase Transition ◽  
Gravitational Waves ◽  
High Energy ◽  
Neutrino Masses ◽  
Symmetric Model ◽  
First Order ◽  
First Order Phase Transition ◽  
Signal Production ◽  
The Right ◽  
First Order Phase

Abstract The left-right symmetric model (LRSM) is a well-motivated framework to restore parity and implement seesaw mechanisms for the tiny neutrino masses at or above the TeV-scale, and has a very rich phenomenology at both the high-energy and high-precision frontiers. In this paper we examine the phase transition and resultant gravitational waves (GWs) in the minimal version of LRSM. Taking into account all the theoretical and experimental constraints on LRSM, we identify the parameter regions with strong first-order phase transition and detectable GWs in the future experiments. It turns out in a sizeable region of the parameter space, GWs can be generated in the phase transition with the strength of 10−17 to 10−12 at the frequency of 0.1 to 10 Hz, which can be detected by BBO and DECIGO. Furthermore, GWs in the LRSM favor a relatively light SU(2)R-breaking scalar $$ {H}_3^0 $$ H 3 0 , which is largely complementary to the direct searches of a long-lived neutral scalar at the high-energy colliders. It is found that the other heavy scalars and the right-handed neutrinos in the LRSM also play an important part for GW signal production in the phase transition.

Beyond the Schwarzschild Metric

2018 ◽  
Author(s):  
David M. Wittman
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Gravitational Waves ◽  
Test Particle ◽  
Direct Detection ◽  
Relativistic Effects ◽  
Big Bang ◽  
Clusters Of Galaxies ◽  
General Relativistic ◽  
The Universe

General relativity explains much more than the spacetime around static spherical masses.We briefly assess general relativity in the larger context of physical theories, then explore various general relativistic effects that have no Newtonian analog. First, source massmotion gives rise to gravitomagnetic effects on test particles.These effects also depend on the velocity of the test particle, which has substantial implications for orbits around black holes to be further explored in Chapter 20. Second, any changes in the sourcemass ripple outward as gravitational waves, and we tell the century‐long story from the prediction of gravitational waves to their first direct detection in 2015. Third, the deflection of light by galaxies and clusters of galaxies allows us to map the amount and distribution of mass in the universe in astonishing detail. Finally, general relativity enables modeling the universe as a whole, and we explore the resulting Big Bang cosmology.

SHOCK WAVE COSMOLOGY INSIDE A BLACK HOLE: THE CASE OF NON-CRITICAL EXPANSION

2004 ◽  
Vol 01 (03) ◽  
pp. 429-443
Author(s):  
JOEL SMOLLER ◽  
BLAKE TEMPLE
Keyword(s):  
Shock Wave ◽  
Black Hole ◽  
Equation Of State ◽  
Closed System ◽  
Big Bang ◽  
Speed Of Light ◽  
State Formula ◽  
The Big Bang

We derive and analyze the equations that extend the results in [20,21] to the case of non-critical expansion k≠0. By an asymptotic argument we show that the equation of state [Formula: see text] plays the same distinguished role in the analysis when k≠0 as it does when k=0: only for this equation of state does the shock emerge from the Big Bang at a finite nonzero speed — the speed of light. We also obtain a simple closed system that extends the case [Formula: see text] considered in [20,21] to the case of a general positive, increasing, convex equation of state p=p(ρ).

scholarly journals Minimal scoto-seesaw mechanism with spontaneous CP violation

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
D. M. Barreiros ◽  
F. R. Joaquim ◽  
R. Srivastava ◽  
J. W. F. Valle
Keyword(s):  
Dark Matter ◽  
Cp Violation ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Discrete Symmetry ◽  
Double Beta Decay ◽  
Neutrino Masses ◽  
Seesaw Mechanism ◽  
Cosmological Observations ◽  
Scalar Singlet

Abstract We propose simple scoto-seesaw models to account for dark matter and neutrino masses with spontaneous CP violation. This is achieved with a single horizontal $$ {\mathcal{Z}}_8 $$ Z 8 discrete symmetry, broken to a residual $$ {\mathcal{Z}}_2 $$ Z 2 subgroup responsible for stabilizing dark matter. CP is broken spontaneously via the complex vacuum expectation value of a scalar singlet, inducing leptonic CP-violating effects. We find that the imposed $$ {\mathcal{Z}}_8 $$ Z 8 symmetry pushes the values of the Dirac CP phase and the lightest neutrino mass to ranges already probed by ongoing experiments, so that normal-ordered neutrino masses can be cornered by cosmological observations and neutrinoless double beta decay experiments.

Gravitational waves: A probe to the physics in the early universe

2015 ◽  
Vol 30 (28n29) ◽  
pp. 1545005
Author(s):  
Qing-Guo Huang
Keyword(s):  
Quantum Theory ◽  
Gravitational Waves ◽  
Early Universe ◽  
Upper Bound ◽  
Planck Scale ◽  
Big Bang ◽  
Planck Data ◽  
Inflationary Scenario ◽  
Fundamental Scale ◽  
The Big Bang

Gravitational waves can escape from the big bang and can be taken as a probe to the physics, in particular the inflation, in the early universe. Planck scale is a fundamental scale for quantum theory of gravity. Requiring the excursion distance of inflaton in the field space during inflation yields an upper bound on the tensor-to-scalar ratio. For example, [Formula: see text] for [Formula: see text]. In the typical inflationary scenario, we predict [Formula: see text] and [Formula: see text] which are consistent with Planck data released in 2015 quite well. Subtracting the contribution of thermal dust measured by Planck, BICEP2 data implies [Formula: see text] which is the tightest bound on the tensor-to-scalar ratio from current experiments.

scholarly journals A Sterile Neutrino Scenario Constrained By Experiments and Cosmology

1997 ◽  
Vol 12 (21) ◽  
pp. 3669-3694 ◽  
Author(s):  
Nobuchika Okada ◽  
Osamu Yasuda
Keyword(s):  
Total Mass ◽  
Sterile Neutrino ◽  
Neutrinoless Double Beta Decay ◽  
Big Bang ◽  
Double Beta Decay ◽  
Big Bang Nucleosynthesis ◽  
Negative Results ◽  
Equivalent Number ◽  
Mixing Matrix ◽  
Model Independent

We analyze a scheme in which three active neutrinos and one sterile neutrino account for the solar, the atmospheric and the LSND neutrino anomalies in a model-independent way. It is shown that if the equivalent number, Nν, of the light neutrino species is less than 4, then the constraints from these anomalies, accelerator and reactor experiments and big bang nucleosynthesis force a general 4 × 4 mixing matrix to be effectively split into two 2 × 2 matrices. If these neutrinos are of the Majorana type, then negative results of neutrinoless double beta decay experiments imply that the total mass of neutrinos is not sufficient to account for all the hot dark matter components.

scholarly journals NEUTRINO MASSES, LEPTON FLAVOR MIXING AND LEPTOGENESIS IN THE MINIMAL SEESAW MODEL

2007 ◽  
Vol 16 (01) ◽  
pp. 1-50 ◽  
Author(s):  
WAN-LEI GUO ◽  
ZHI-ZHONG XING ◽  
SHUN ZHOU
Keyword(s):  
Beta Decay ◽  
Neutrino Mass ◽  
Mass Matrix ◽  
Majorana Neutrino ◽  
Double Beta Decay ◽  
Neutrino Mixing ◽  
Lepton Flavor ◽  
Seesaw Model ◽  
Flavor Mixing ◽  
Majorana Neutrinos

We present a review of neutrino phenomenology in the minimal seesaw model (MSM), an economical and intriguing extension of the Standard Model with only two heavy right-handed Majorana neutrinos. Given current neutrino oscillation data, the MSM can predict the neutrino mass spectrum and constrain the effective masses of the tritium beta decay and the neutrinoless double-beta decay. We outline five distinct schemes to parameterize the neutrino Yukawa-coupling matrix of the MSM. The lepton flavor mixing and baryogenesis via leptogenesis are investigated in some detail by taking account of possible texture zeros of the Dirac neutrino mass matrix. We derive an upper bound on the CP-violating asymmetry in the decay of the lighter right-handed Majorana neutrino. The effects of the renormalization-group evolution on the neutrino mixing parameters are analyzed, and the correlation between the CP-violating phenomena at low and high energies is highlighted. We show that the observed matter-antimatter asymmetry of the Universe can naturally be interpreted through the resonant leptogenesis mechanism at the TeV scale. The lepton-flavor-violating rare decays, such as μ→e+γ, are also discussed in the supersymmetric extension of the MSM.

scholarly journals The holographic spacetime model of cosmology

2018 ◽  
Vol 27 (14) ◽  
pp. 1846005 ◽  
Author(s):  
Tom Banks ◽  
W. Fischler
Keyword(s):  
Dark Matter ◽  
Gravitational Waves ◽  
Structure Formation ◽  
Big Bang ◽  
Baryon Asymmetry ◽  
Gaussian Fluctuations ◽  
Primordial Gravitational Waves ◽  
Conventional Models ◽  
Non Gaussian ◽  
The Big Bang

This essay outlines the Holographic Spacetime (HST) theory of cosmology and its relation to conventional theories of inflation. The predictions of the theory are compatible with observations, and one must hope for data on primordial gravitational waves or non-Gaussian fluctuations to distinguish it from conventional models. The model predicts an early era of structure formation, prior to the Big Bang. Understanding the fate of those structures requires complicated simulations that have not yet been done. The result of those calculations might falsify the model, or might provide a very economical framework for explaining dark matter and the generation of the baryon asymmetry.

New Limits on Neutrino Masses and Right-Handed Currents from Double Beta Decay

1986 ◽  
pp. 686-691
Author(s):  
D. O. Caldwell ◽  
R. M. Eisberg ◽  
D. M. Grumm ◽  
D. L. Hale ◽  
M. S. Witherell ◽  
...  
Keyword(s):  
Beta Decay ◽  
Double Beta Decay ◽  
Neutrino Masses
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