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Cosmological collider signals of primordial non-Gaussianity arise at tree level when an extra scalar has Hubble mass during inflation. We critically review the formalism finding that a large class of inflationary theories, based on…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-14 Shuntaro Aoki , Anish Ghoshal , Alessandro Strumia

In the early Universe above the weak scale, both baryon $B$ and lepton $L$ numbers are violated by nonperturabive effects in the Standard Model while $B-L$ remains conserved. Introducing new physics which violates perturbatively $L$ and/or…

High Energy Physics - Phenomenology · Physics 2022-02-09 Chee Sheng Fong

We discuss scalar triplet leptogenesis in a specific left-right symmetric seesaw model. We show that the Majorana phases that are present in the model can be effectively used to saturate the existing upper limit on the CP-asymmetry of the…

High Energy Physics - Phenomenology · Physics 2008-11-26 Tomas Hallgren , Thomas Konstandin , Tommy Ohlsson

We study the cosmological collider signatures in the Higgs-$R^2$ inflation model. We consider two distinct types of signals: one originating from the inflaton coupling to Standard Model fermions and gauge bosons, and another arising from…

High Energy Physics - Phenomenology · Physics 2024-02-27 Yohei Ema , Sarunas Verner

We argue that a non-thermal leptogenesis occurs spontaneously, without direct couplings of the inflaton with right-handed neutrinos, in a wide class of high-scale inflation models such as the chaotic and hybrid inflation. It is only a…

High Energy Physics - Phenomenology · Physics 2008-11-26 Motoi Endo , Fuminobu Takahashi , T. T. Yanagida

We relate leptogenesis in a class of theories to low-energy experimental observables: quark and lepton masses and mixings. With reasonable assumptions motivated by grand unification, one can show that the CP-asymmetry parameter takes a…

High Energy Physics - Phenomenology · Physics 2009-11-07 M. S. Berger , Kim Siyeon

We present a model with minimal assumptions for non-thermal leptogenesis with almost degenerate superheavy right-handed neutrinos in a supersymmetric set up. In this scenario a gauge singlet inflaton is directly coupled to the right-handed…

High Energy Physics - Phenomenology · Physics 2009-11-07 Rouzbeh Allahverdi , Anupam Mazumdar

We present a scenario of nonthermal leptogenesis following supersymmetric hybrid inflation, in the case where inflaton decay to both heavy right handed neutrino and SU(2)_L triplet superfields is kinematically disallowed. Lepton asymmetry…

High Energy Physics - Phenomenology · Physics 2009-11-10 Thomas Dent , George Lazarides , Roberto Ruiz de Austri

We study ``soft leptogenesis'', a new mechanism of leptogenesis which does not require flavour mixing among the right-handed neutrinos. Supersymmetry soft-breaking terms give a small mass splitting between the CP-even and CP-odd…

High Energy Physics - Phenomenology · Physics 2010-04-05 Giancarlo D'Ambrosio , Gian F. Giudice , Martti Raidal

Among the mechanisms which successfully explain the generation of the Baryon Asymmetry of the Universe, Leptogenesis through right-handed neutrino decays is especially attractive. Unfortunately, this theory suffers from a lack of…

High Energy Physics - Phenomenology · Physics 2009-05-25 G. Vertongen

Primordial non-Gaussianity generated by additional fields during inflation offers a compelling observational target. Heavy fields imprint characteristic oscillatory signals in non-Gaussian correlation functions of the inflaton, a process…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-13 Daniel Green , Jiashu Han , Benjamin Wallisch

Two of the important implications of the seesaw mechanism are: (i) a simple way to understand the small neutrino masses, and (ii) the origin of matter-anti-matter asymmetry in the universe via the leptogenesis mechanism. For TeV-scale…

High Energy Physics - Phenomenology · Physics 2020-01-29 P. S. Bhupal Dev , Rabindra N. Mohapatra , Yongchao Zhang

Future measurements of primordial non-Gaussianity can reveal cosmologically produced particles with masses of order the inflationary Hubble scale and their interactions with the inflaton, giving us crucial insights into the structure of…

High Energy Physics - Phenomenology · Physics 2018-05-15 Soubhik Kumar , Raman Sundrum

Leptogenesis can successfully explain the matter-antimatter asymmetry via out-of-equilibrium decays of heavy Majorana neutrinos in the early Universe. In this article, we focus on non-resonant thermal leptogenesis and the possibility of…

High Energy Physics - Phenomenology · Physics 2018-09-06 K. Moffat , S. Pascoli , S. T. Petcov , H. Schulz , J. Turner

No-scale supergravity provides a successful framework for Starobinsky-like inflation models. Two classes of models can be distinguished depending on the identification of the inflaton with the volume modulus, $T$ (C-models), or a…

High Energy Physics - Phenomenology · Physics 2020-01-15 Kunio Kaneta , Yann Mambrini , Keith A. Olive , Sarunas Verner

It is well-known that leptogenesis in low energy scale is difficult in the conventional Type-I seesaw mechanism with hierarchical right-handed neutrino masses. We show that in a class of two Higgs doublet model, where one Higgs doublet…

High Energy Physics - Phenomenology · Physics 2011-07-03 Naoyuki Haba , Osamu Seto

It is well known that the leptogenesis mechanism offers an attractive possibility to explain the baryon asymmetry of the universe. Its particular robustness however comes with one major difficulty: it will be very hard if not impossible to…

High Energy Physics - Phenomenology · Physics 2009-03-06 J. -M. Frère , T. Hambye , G. Vertongen

In this talk we present a mechanism for leptogenesis which is based on gravity waves produced during inflation. We show that when inflation is driven by a pseudo-scalar field the metric perturbations generated during inflation can become…

High Energy Physics - Phenomenology · Physics 2014-03-18 S. H. Alexander , M. Peskin , M. M. Sheikh-Jabbari

A decade ago, the first leptogenesis model based on inflation was proposed, where the complex phase of the inflaton field carries lepton number. If the inflaton field is an axion, it can couple to gravitational waves and gauge fields via.…

High Energy Physics - Theory · Physics 2016-11-23 Stephon H. S. Alexander

The extension of the Standard Model by heavy right-handed neutrinos can simultaneously explain the observed neutrino masses via the seesaw mechanism and the baryon asymmetry of the Universe via leptogenesis. If the mass of the heavy…

High Energy Physics - Phenomenology · Physics 2020-07-10 Marco Drewes , Bjorn Garbrecht , Dario Gueter , Juraj Klaric
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