Mikhail Chapochnikov

Chat with Graph Search

Ask any question about EPFL courses, lectures, exercises, research, news, etc. or try the example questions below.

DISCLAIMER: The Graph Chatbot is not programmed to provide explicit or categorical answers to your questions. Rather, it transforms your questions into API requests that are distributed across the various IT services officially administered by EPFL. Its purpose is solely to collect and recommend relevant references to content that you can explore to help you answer your questions.

In the present paper, we revisit gravitational theories which are invariant under TDiffs-transverse (volume-preserving) diffeomorphisms and global scale transformations. It is known that these theories can be rewritten in an equivalent diffeomorphism-invar ...

We show how Einstein-Cartan gravity can accommodate both global scale and local scale (Weyl) invariance. To this end, we construct a wide class of models with nonpropagating torsion and a nonminimally coupled scalar field. In phenomenological applications ...

The correlators of currents {Mathematical expression}Q, γvγ5Q, q and Q being correspondingly light and heavy quark fields, in hot hadronic matter are investigated by means of finite temperature QCD sum rules. At T≳ 100 MeV the modification of the effective spectrum parameters takes place, similar to that found earlier in the correlators of light quark currents. At T≳150 MeV the form of the spectrum is obtained, which indicates an appearance in hadronic matter of quasifree quarks with nonzero mass being fixe

We review briefly the different constraints on the three right-handed neutrinos of the nu MSM, an extension of the Standard Model that can explain baryon asymmetry, dark matter and neutrino masses. We include in the discussion the proposed experiments on m ...

We find the conditions under which scale-invariant Einstein-Cartan gravity with scalar matter fields leads to an approximate conformal invariance of the flat space particle theory up to energies of the order of the Planck mass. In the minimal setup, these ...

We consider the effects of sphaleronlike transitions in the high-temperature QCD plasma. Because of the chiral anomaly, these imply rapid chirality change, and strongly influence the dynamics of any axionic fields that may couple to the topological winding number of QCD. We derive a coupled set of equations describing the evolution of the axion field and chiral fermion density at high temperatures. The unsuppressed sphaleronlike transitions result in the damping of coherent axionic oscillations. The implica

I will discuss a proposal for a unified solution of the problems of neutrino masses, dark matter, baryon asymmetry of the Universe and inflation, which does not require introduction of any new energy scale besides already known, namely the electroweak and the Planck scales. This point of view, supplemented by a requirement of simplicity, has a number of experimental predictions which can be tested, at least partially, with the use of existing accelerators and the LHC, with current and future X-ray telescope

In an extension of the Standard Model by three relatively light right-handed neutrinos (the νMSM model) the role of the dark matter particle is played by the lightest sterile neutrino. We demonstrate that the observations of the extragalactic x-ray backgro ...

We present a comprehensive overview of an extension of the Standard Model that contains three right-handed (sterile) neutrinos with masses below the electroweak scale [the Neutrino Minimal Standard Model (vMSM)]. We consider the history of the Universe fro ...

The SHiP-charm project was proposed to measure the associated charm production induced by 400 GeV/c protons in a thick target, including the contribution from cascade production. An optimisation run was performed in July 2018 at CERN SPS using a hybrid set ...

Coloured scalar quarks which are present in some theories (e.g. SUSY QCD) produce a new family of hadrons. Some of these new hadrons could be absolutely stable and could be produced and preserved up to now in the course of cosmological expansion. We derive constraints on the properties of such hadrons imposed by the results of the searches for various exotic particles in the terrestrial matter and discuss an alternative experimental approach to such searches which might be more successful. © 1984 Società It

We initiate the analysis of the inflationary dynamics in Weyl-invariant Einstein–Cartan gravity nonminimally coupled to the Standard Model of particle physics. We take the axion-like particle of gravitational origin to be heavy and show that inflation with the Higgs field can be accommodated in this framework.

We consider the possibility of localizing gravity on a Nielsen-Olesen vortex in the context of the Abelian Higgs model. The vortex lives in a six-dimensional space-time with negative bulk cosmological constant. In this model we find a region of the parameter space leading, simultaneously, to warped compactification and to regular space-time geometry. A thin defect limit is studied. Regular solutions describing warped compactifications in the case of higher winding number are also presented. © 2001 Elsevier

Our Universe is charge-asymmetric: it contains no antimatter in amounts comparable to matter. This fact provides cosmological evidence for the nonconservation of baryon number as well as for C and CP breaking. We review the problem of the matter-antimatter ...

The connection is discussed between the phase transitions in the hot hadronic matter and characteristic mass parameters of the non-perturbative QCD. The spectrum of the hot hadronic matter containing light coloured scalar fields in addition to ordinary quarks and gluons is investigated by means of the finite-temperature QCD sum rules. A qualitative rearrangement of the spectrum is shown to occur at some temperature T cr, which is entirely fixed by the value of the scalar field condensate 〈φ † φ〉. A variety

Gravity can give rise to (pseudo)scalar fields—for instance due to torsion. In particular, axions of gravitational origin have been proposed as a minimal and compelling solution to the strong CP problem. In this Letter, we critically examine the feasibility of this proposal. We demonstrate that models in which the scalar field couples to fermionic currents only through derivatives do not yield a satisfactory axion. Moreover, we identify the necessary conditions for generating a gravitational axion through q

The classical Lagrangian of the Standard Model enjoys the symmetry of the full conformal group if the mass of the Higgs boson is put to zero. This is a hint that conformal symmetry may play a fundamental role in the ultimate theory describing nature. The o ...

The Scattering and Neutrino Detector at the LHC (SND@LHC) started taking data at the beginning of Run 3 of the LHC. The experiment is designed to perform measurements with neutrinos produced in proton-proton collisions at the LHC in an energy range between ...

We show that the extension of the standard model by three right-handed neutrinos with masses smaller than the electroweak scale (the νMSM) can explain simultaneously dark matter and baryon asymmetry of the universe and be consistent with the experiments on ...

We address the question whether a scale invariant theory can contain interacting minimal fields of canonical dimensionality. It is known that the answer to this question is negative provided the scale symmetry is respected by the ground state. We present a ...

Mikhail Chapochnikov

Chat with Graph Search

Scale-invariant alternatives to general relativity. II. Dilaton properties

Scale and Weyl invariance in Einstein-Cartan gravity

BOUND STATES OF LIGHT AND HEAVY QUARKS IN HOT HADRONIC MATTER

The nu MSM and muon to electron conversion experiments

Scale invariant Einstein-Cartan gravity and flat space conformal symmetry

SPHALERONS AND AXION DYNAMICS IN HIGH TEMPERATURE QCD

Cosmology versus standard model

The masses of active neutrinos in the nuMSM from X-ray astronomy

The role of sterile neutrinos in cosmology and astrophysics

Reconstruction of 400 GeV/c proton interactions with the SHiP-charm project

COLORED SCALARS AND COSMOLOGY

Weyl-invariant Einstein–Cartan gravity with a heavy ALP: Higgs inflation and α-attractors

Warped compactification on Abelian vortex in six dimensions

Baryon asymmetry of the universe and neutrinos

HADRONIC MASS SCALES AND PHASE TRANSITIONS IN QCD

Gravitational Origin of the QCD Axion

Exact quantum conformal symmetry, its spontaneous breakdown, and gravitational Weyl anomaly

Measurement of the muon flux at the SND@LHC experiment

The nuMSM, dark matter and baryon asymmetry of the universe

Spontaneously broken scale invariance and minimal fields of canonical dimensionality