Majorana dark matter through the Higgs portal under the vacuum stability lamppost

We present a renormalization group study of the scalar potential in a minimal U(1) B−L extension of the Standard Model involving one extra heavier Higgs and three heavy right-handed neutrinos with family universal B-L charge assignments. We implement a type-I seesaw for the masses of the light neutrinos of the Standard Model. In particular, compared to a previous study, we perform a two-loop extension of the evolution, showing that two-loop effects are essential for the study of the stability of the scalar potential up to the Planck scale. The analysis includes the contribution of the kinetic mixing between the two abelian gauge groups, which is radiatively generated by the evolution, and the one-loop matching conditions at the electroweak scale. By requiring the stability of the potential up to the Planck mass, significant constraints on the masses of the heavy neutrinos, on the gauge couplings and the mixing in the Higgs sector are identified.

Section: Stability and The Role Of The Yukawa Couplingsmentioning

confidence: 99%

Constraints on abelian extensions of the Standard Model from two-loop vacuum stability and U(1) B−L

Corianò

Rose

Marzo

2016

“…Clearly the goal is no longer to derive bounds on its mass, but rather to perform more refined analyses that should allow to discriminate between absolute stability or metastability for the EW vacuum [18][19][20][21], to study the cosmological impact of the vacuum stability condition during and after inflation [22][23][24][25][26][27][28][29][30][31][32], and to test the impact that different NP scenarios can have on the vacuum stability condition [18,[33][34][35][36][37][38][39][40][41][42][43][44]. This renewed interest also prompted a more careful treatment of issues as the gauge invariance of the vacuum decay rate and the contribution of zero modes to the quantum fluctuation determinant [45][46][47][48][49][50].…”

Section: Introductionmentioning

confidence: 99%

Impact of new physics on the EW vacuum stability in a curved spacetime background

Bentivegna

Branchina

Contino

et al. 2017

It has been recently shown that, contrary to an intuitive decoupling argument, the presence of new physics at very large energy scales (say around the Planck scale) can have a strong impact on the electroweak vacuum lifetime. In particular, the vacuum could be totally destabilized. This study was performed in a flat spacetime background, and it is important to extend the analysis to curved spacetime since these are Planckian-physics effects. It is generally expected that under these extreme conditions gravity should totally quench the formation of true vacuum bubbles, thus washing out the destabilizing effect of new physics. In this work we extend the analysis to curved spacetime and show that, although gravity pushes toward stabilization, the destabilizing effect of new physics is still (by far) the dominating one. In order to get model independent results, high energy new physics is parametrized in two different independent ways: as higher order operators in the Higgs field, or introducing new particles with very large masses. The destabilizing effect is observed in both cases, hinting at a general mechanism that does not depend on the parametrization details for new physics, thus maintaining the results obtained from the analysis performed in flat spacetime.

“…The portal couplings ( , α) and the mass of the mediators (m Z , m h d ) can be constrained from various experimental observations (see [51] for example). In this section we discuss the relevant constraints in m Z -and m h d -sin α planes.…”

Section: Constraints On the Portal Couplingsmentioning

confidence: 99%

When freeze-out occurs due to a non-Boltzmann suppression: a study of degenerate dark sector

Biswas

Ganguly

Roy

2021

Exponential suppression or commonly known as the Boltzmann suppression in the number density of dark matter is the key ingredient for creating chemical imbalance prior to the usual thermal freeze-out. A degenerate/quasi-degenerate dark sector can experience a different exponential suppression in the number density analogous to the radioactive decay law leading to a delayed freeze-out mechanism of dark matter known as the co-decaying dark matter. In this work, we study the dynamics of a multicomponent dark matter from thermally decoupled degenerate dark sector in a hidden U(1)X extension of the Standard Model. We compute the relic density of dark matter frozen-out through the co-decaying mechanism by solving four coupled Boltzmann equations. We demonstrate how temperature T′ of the dark sector changes due to all types of 3 → 2 and 2 → 2 interactions along with the eternal expansion of the Universe. We find that 3 → 2 interactions enhance T′ by producing energetic particles in the dark sector while the excess heat is transferred by 2 → 2 interactions to the entire dark sector. As the direct detection is possible only through the feeble portal couplings, we investigate the neutrino and γ-ray signals from dark matter annihilation via one step cascade processes and compare our results with the measured fluxes of atmospheric neutrinos by Super-Kamiokande and diffuse γ-rays by Fermi-LAT, EGRET, INTEGRAL collaborations. We find that the present scenario easily evades all the existing bounds from atmospheric neutrino and diffuse γ-ray observations for degenerate dark sector. However, the constraints are significant for quasi degenerate scenario.