Publications by Andrey Shkerin

Preheating in Palatini Higgs inflation on the lattice

Adrien Florio, Andrey Shkerin, Inar Timiryasov, Juraj Klaric

We study preheating following Higgs inflation in the Palatini formulation of gravity. We numerically evolve perturbations of the radial mode of the Higgs field and that of three scalars modeling the gauge bosons. We compare the two non-perturbative mechani ...

IOP Publishing Ltd2022

Einstein-Cartan Portal to Dark Matter

Mikhail Chapochnikov, Andrey Shkerin, Inar Timiryasov, Sebastian Zell

It is well known since the works of Utiyama and Kibble that the gravitational force can be obtained by gauging the Poincare group, which puts gravity on the same footing as the standard model fields. The resulting theory-Einstein-Cartan gravity-inevitably ...

AMER PHYSICAL SOC2021

Standard model meets gravity: Electroweak symmetry breaking and inflation

Mikhail Chapochnikov, Andrey Shkerin, Sebastian Zell

We propose a model for combining the Standard Model (SM) with gravity. It relies on a nonminimal coupling of the Higgs field to the Ricci scalar and on the Palatini formulation of gravity. Without introducing any new degrees of freedom in addition to those ...

American Physical Society2021

Einstein-Cartan gravity, matter, and scale-invariant generalization (vol 10, 177, 2020)

Mikhail Chapochnikov, Andrey Shkerin, Inar Timiryasov, Sebastian Zell

Springer Nature2021

Higgs inflation in Einstein-Cartan gravity

Mikhail Chapochnikov, Andrey Shkerin, Inar Timiryasov, Sebastian Zell

We study inflation driven by the Higgs field in the Einstein-Cartan formulation of gravity. In this theory, the presence of the Holst and Nieh-Yan terms with the Higgs field non-minimally coupled to them leads to three additional coupling constants. For a ...

IOP PUBLISHING LTD2021

Higgs inflation in Einstein-Cartan gravity (vol 02, 008, 2021)

Mikhail Chapochnikov, Andrey Shkerin, Inar Timiryasov, Sebastian Zell

IOP Publishing Ltd2021

Matter matters in Einstein-Cartan gravity

Mikhail Chapochnikov, Georgios Karananas, Andrey Shkerin, Sebastian Zell

We study scalar, fermionic and gauge fields coupled nonminimally to gravity in the Einstein-Cartan formulation. We construct a wide class of models with nondynamical torsion whose gravitational spectra comprise only themassless graviton. Eliminating nonpro ...

American Physical Society2021

Quantum effects in Palatini Higgs inflation

Mikhail Chapochnikov, Andrey Shkerin, Sebastian Zell

We study quantum effects in Higgs inflation in the Palatini formulation of gravity, in which the metric and connection are treated as independent variables. We exploit the fact that the cutoff, above which perturbation theory breaks down, is higher than th ...

IOP PUBLISHING LTD2020

Review of Nontopological Solitons in Theories with U(1)-Symmetry

Andrey Shkerin

We provide a review of nontopological solitonic solutions arising in theories with a complex scalar field and global or gauge U(1)-symmetry. It covers Q-balls, homogeneous charged scalar condensates, and nonlinear localized holes and bulges in a classicall ...

2020

Einstein-Cartan gravity, matter, and scale-invariant generalization

Mikhail Chapochnikov, Andrey Shkerin, Inar Timiryasov, Sebastian Zell

We study gravity coupled to scalar and fermion fields in the Einstein-Cartan framework. We discuss the most general form of the action that contains terms of mass dimension not bigger than four, leaving out only contributions quadratic in curvature. By res ...

Springer Nature2020

Dilaton-assisted generation of the Fermi scale from the Planck scale

Andrey Shkerin

In scale-invariant theories of gravity the Planck mass M-p, which appears due to spontaneous symmetry breaking, can be the only scale at the classical level. It was argued that the second scale can be generated by a quantum nonperturbative gravitational ef ...

American Physical Society2019

Vibrational modes of Q-balls

Andrey Shkerin

We study linear perturbations of classically stable Q-balls in theories admitting analytic solutions. Although the corresponding boundary value problem is non-Hermitian, the analysis of perturbations can also be performed analytically in certain regimes. W ...

American Physical Society2018

On massive Nambu-Goldstone fields

Andrey Shkerin

We consider two theories undergoing the same spontaneous symmetry breaking pattern but with different representations of an order parameter under the Lorentz group. The effective description of the first theory includes a massive Nambu-Goldstone field, whi ...

EDP SCIENCES2018

Euclidean classical solutions in quantum field theory and gravity: Higgs vacuum metastability and the hierarchy problem

Andrey Shkerin

The thesis is dedicated to two groups of questions arising in modern particle physics and cosmology. The first group concerns with the problem of stability of the electroweak (EW) vacuum in different environments. Due to its phenomenological significance, ...

EPFL2018

Towards a non-perturbative approach to the Hierarchy problem

Andrey Shkerin

In this report, based on [1], we suggest that the hierarchy between the Electroweak (EW) and the Planck scales can emerge due to a nonperturbative effect that relates low-energy and strong-gravity physics. In this mechanism, the EW scale results from an ex ...

EDP SCIENCES2018

Conformal symmetry: Towards the link between the Fermi and the Planck scales

Mikhail Chapochnikov, Andrey Shkerin

If the mass of the Higgs boson is put to zero, the classical Lagrangian of the Standard Model (SM) becomes conformally invariant (CI). Taking into account quantum non-perturbative QCD effects violating CI leads to electroweak symmetry breaking with the sca ...

ELSEVIER SCIENCE BV2018

Gravity, scale invariance and the hierarchy problem

Mikhail Chapochnikov, Andrey Shkerin

Combining the quantum scale invariance with the absence of new degrees of freedom above the electroweak scale leads to stability of the latter against perturbative quantum corrections. Nevertheless, the hierarchy between the weak and the Planck scales rema ...

Springer Nature2018

Solving puzzles of spontaneously broken spacetime symmetries

Andrey Shkerin

We establish a classical analog of the Nambu-Goldstone theorem for spontaneous breaking of spacetime symmetries. It provides a counting rule for independent Nambu-Goldstone fields and states which of them are gapped. We demonstrate that only those symmetry ...

American Physical Society2018

Characteristic modes of vibration of Q-balls

Andrey Shkerin

In this report, based on [1], we study analytically small perturbations of classically stable Q-balls in 3+1 dimensions. Models with flat and polynomial potentials are considered. We find that large Q-balls in the model with the flat potential possess soft ...

EDP SCIENCES2018

Electroweak vacuum stability in the Higgs-Dilaton theory

Andrey Shkerin

We study the stability of the Electroweak (EW) vacuum in a scale-invariant extension of the Standard Model and General Relativity, known as a Higgs-Dilaton theory. The safety of the EW vacuum against possible transition towards another vacuum is a necessar ...

Springer Nature2017