Publications by Oleg Ruchayskiy

The present and future status of heavy neutral leptons

Alexey Boyarsky, Oleg Ruchayskiy, Lesya Shchutska, Marco Drewes, Jean-Loup Tastet, Inar Timiryasov, Juraj Klaric

The existence of nonzero neutrino masses points to the likely existence of multiple Standard Model neutral fermions. When such states are heavy enough that they cannot be produced in oscillations, they are referred to as heavy neutral leptons (HNLs). In th ...

2022

An allowed window for heavy neutral leptons below the kaon mass

Alexey Boyarsky, Oleg Ruchayskiy, Inar Timiryasov, Juraj Klaric, Kyrylo Bondarenko

The extension of the Standard Model with two gauge-singlet Majorana fermions can simultaneously explain two beyond-the-Standard-model phenomena: neutrino masses and oscillations, as well as the origin of the matter-antimatter asymmetry in the Universe. The ...

Springer Nature2021

Feebly-Interacting Particles:FIPs 2020 Workshop Report

Martin Bauer, Alexey Boyarsky, Oleg Ruchayskiy, Lesya Shchutska, Marco Drewes

With the establishment and maturation of the experimental programs searching for new physics with sizeable couplings at the LHC, there is an increasing interest in the broader particle and astrophysics community for exploring the physics of light and feebl ...

2021

Sensitivity of the SHiP experiment to dark photons decaying to a pair of charged particles

Aurelio Bay, Mikhail Chapochnikov, Guido Haefeli, Alexey Boyarsky, Hans Dijkstra, Alexandre Emmanuel Grandchamp, Oleg Ruchayskiy, Lesya Shchutska, Nikolaos Charitonidis, Jean-Loup Tastet, Sergei Smirnov, Anton Petrov, Inar Timiryasov, Maria Elena Stramaglia, Ana Bárbara Rodrigues Cavalcante, Federico Leo Redi, Elena Graverini, Ekaterina Kuznetsova

Dark photons are hypothetical massive vector particles that could mix with ordinary photons. The simplest theoretical model is fully characterised by only two parameters: the mass of the dark photon m(gamma)D and its mixing parameter with the photon, epsil ...

2021

Measurement of the muon flux from 400 GeV/c protons interacting in a thick molybdenum/tungsten target

Aurelio Bay, Mikhail Chapochnikov, Guido Haefeli, Alexey Boyarsky, Hans Dijkstra, Alexandre Emmanuel Grandchamp, Oleg Ruchayskiy, Lesya Shchutska, Nikolaos Charitonidis, Jean-Loup Tastet, Sergei Smirnov, Anton Petrov, Inar Timiryasov, Maria Elena Stramaglia, Ana Bárbara Rodrigues Cavalcante, Federico Leo Redi, Elena Graverini, Ekaterina Kuznetsova

The SHiP experiment is proposed to search for very weakly interacting particles beyond the Standard Model which are produced in a 400 GeV/c proton beam dump at the CERN SPS. About 1011muons per spill will be produced in the dump. To design the experiment s ...

2020

The magnet of the scattering and neutrino detector for the SHiP experiment at CERN

Sebastian Gerlach, Aurelio Bay, Mikhail Chapochnikov, Guido Haefeli, Alexey Boyarsky, Hans Dijkstra, Sun Hee Kim, Alexandre Emmanuel Grandchamp, Oleg Ruchayskiy, Lesya Shchutska, Nikolaos Charitonidis, Jean-Loup Tastet, Sergei Smirnov, Anton Petrov, Inar Timiryasov, Maria Elena Stramaglia, Ana Bárbara Rodrigues Cavalcante, Federico Leo Redi, Elena Graverini, Ekaterina Kuznetsova

The Search for Hidden Particles (SHiP) experiment proposal at CERN demands a dedicated dipole magnet for its scattering and neutrino detector. This requires a very large volume to be uniformly magnetized at B > 1.2 T, with constraints regarding the inner i ...

2020

Fast simulation of muons produced at the SHiP experiment using Generative Adversarial Networks

Sebastian Gerlach, Aurelio Bay, Mikhail Chapochnikov, Guido Haefeli, Alexey Boyarsky, Hans Dijkstra, Sun Hee Kim, Alexandre Emmanuel Grandchamp, Oleg Ruchayskiy, Lesya Shchutska, Nikolaos Charitonidis, Jean-Loup Tastet, Sergei Smirnov, Anton Petrov, Inar Timiryasov, Maria Elena Stramaglia, Ana Bárbara Rodrigues Cavalcante, Federico Leo Redi, Elena Graverini, Ekaterina Kuznetsova

This paper presents a fast approach to simulating muons produced in interactions of the SPS proton beams with the target of the SHiP experiment. The SHIP experiment will be able to search for new long-lived particles produced in a 400 GeV/c SPS proton beam ...

2019

21-cm observations and warm dark matter models

Alexey Boyarsky, Oleg Ruchayskiy, Wessel Valkenburg

Observations of the redshifted 21-cm signal (in absorption or emission) allow us to peek into the epoch of the "Dark Ages" and the onset of reionization. These data can provide a novel way to learn about the nature of dark matter, in particular, about the ...

American Physical Society2019

The experimental facility for the Search for Hidden Particles at the CERN SPS

Aurelio Bay, Mikhail Chapochnikov, Guido Haefeli, Alexey Boyarsky, Hans Dijkstra, Sun Hee Kim, Alexandre Emmanuel Grandchamp, Oleg Ruchayskiy, Lesya Shchutska, Nikolaos Charitonidis, Jean-Loup Tastet, Sergei Smirnov, Anton Petrov, Inar Timiryasov, Maria Elena Stramaglia, Ana Bárbara Rodrigues Cavalcante, Federico Leo Redi, Elena Graverini, Ekaterina Kuznetsova

The Search for Hidden Particles (SHiP) Collaboration has shown that the CERN SPS accelerator with its 400 GeV/c proton beam offers a unique opportunity to explore the Hidden Sector [1-3]. The proposed experiment is an intensity frontier experiment which is ...

2019

Probing new physics with displaced vertices: Muon tracker at CMS

Alexey Boyarsky, Oleg Ruchayskiy, Lesya Shchutska, Kyrylo Bondarenko

Long-lived particles can manifest themselves at the LHC via "displaced vertices"-several charged tracks originating from a position separated from the proton interaction point by a macroscopic distance. Here we demonstrate the potential of the muon tracker ...

American Physical Society2019

Sensitivity of the SHiP experiment to Heavy Neutral Leptons

Florian Maria Wurm, Aurelio Bay, Mikhail Chapochnikov, Guido Haefeli, Alexey Boyarsky, Hans Dijkstra, Sun Hee Kim, Oleg Ruchayskiy, Nathalie Sophie Adeline Serra, Lesya Shchutska, Adriano Pastore, Nikolaos Charitonidis, Johannes Richard Cornelis Geerit Kruis, Erica Manfredi, Sargis Hakobyan, Eirini Koukovini Platia, Jean-Loup Tastet, Sergei Smirnov, Anton Petrov, Inar Timiryasov, Maria Elena Stramaglia, Federico Leo Redi, Elena Graverini, Ekaterina Kuznetsova

Heavy Neutral Leptons (HNLs) are hypothetical particles predicted by many extensions of the Standard Model. These particles can, among other things, explain the origin of neutrino masses, generate the observed matter-antimatter asymmetry in the Universe an ...

Springer Nature2019

A White Paper on keV sterile neutrino Dark Matter

Laurent Gastaldo, Igor Tkachev, Alexey Boyarsky, Oleg Ruchayskiy, Julien Lesgourgues, Marco Drewes, Antoine Pierre Emmanuel Alexis Merle, Jan Hamann, Jonathan Leon Wolf

We present a comprehensive review of keV-scale sterile neutrino Dark Matter, collecting views and insights from all disciplines involved - cosmology, astrophysics, nuclear, and particle physics - in each case viewed from both theoretical and experimental/o ...

Iop Publishing Ltd2017

The active muon shield in the SHiP experiment

Sebastian Gerlach, Aurelio Bay, Mikhail Chapochnikov, Alexey Boyarsky, Hans Dijkstra, Sun Hee Kim, Oleg Ruchayskiy, Lesya Shchutska, Sergei Smirnov, Inar Timiryasov, Federico Leo Redi, Elena Graverini, Ekaterina Kuznetsova

The SHiP experiment is designed to search for very weakly interacting particles beyond the Standard Model which are produced in a 400 GeV/c proton beam dump at the CERN SPS. An essential task for the experiment is to keep the Standard Model background leve ...

2017

Searching for decaying dark matter in deep XMM-Newton observation of the Draco dwarf spheroidal

Alexey Boyarsky, Andrii Neronov, Oleg Ruchayskiy

We present results of a search for the 3.5 keV emission line in our recent very long (similar to 1.4 Ms) XMM-Newton observation of the Draco dwarf spheroidal galaxy. The astrophysical X-ray emission from such dark matter-dominated galaxies is faint, thus t ...

Wiley-Blackwell2016

Satellite galaxies in semi-analytic models of galaxy formation with sterile neutrino dark matter

Alexey Boyarsky, Oleg Ruchayskiy

The sterile neutrino is a viable darkmatter candidate that can be produced in the early Universe via non-equilibrium processes, and would therefore possess a highly non-thermal spectrum of primordial velocities. In this paper we analyse the process of stru ...

Wiley-Blackwell2016

A facility to search for hidden particles at the CERN SPS: the SHiP physics case

Mikhail Chapochnikov, Anurag Tripathi, Alexey Boyarsky, Oleg Ruchayskiy, Lesya Shchutska, Marco Drewes, Shintaro Eijima, Kyrylo Bondarenko

This paper describes the physics case for a new fixed target facility at CERN SPS. The SHiP (search for hidden particles) experiment is intended to hunt for new physics in the largely unexplored domain of very weakly interacting particles with masses below ...

Institute of Physics2016

Decaying dark matter: the case for a deep X-ray observation of Draco

Alexey Boyarsky, Oleg Ruchayskiy

Recent studies of M31, the Galactic Centre (GC), and galaxy clusters have made tentative detections of an X-ray line at similar to 3.5 keV that could be produced by decaying dark matter. We use high-resolution simulations of the Aquarius project to predict ...

Oxford University Press2015

Checking the Dark Matter Origin of a 3.53 keV Line with the Milky Way Center

Alexey Boyarsky, Oleg Ruchayskiy

We detect a line at 3.539 +/- 0.011 keV in the deep exposure data set of the Galactic center region, observed with the x-ray multi-mirror mission Newton. The dark matter interpretation of the signal observed in the Perseus galaxy cluster, the Andromeda gal ...

Amer Physical Soc2015

Magnetohydrodynamics of chiral relativistic fluids

Alexey Boyarsky, Oleg Ruchayskiy

We study the dynamics of a plasma of charged relativistic fermions at very high temperature T >> m, where m is the fermion mass, coupled to the electromagnetic field. In particular, we derive a magnetohydrodynamical description of the evolution of such a p ...

American Physical Society2015

A new framework for numerical simulations of structure formation

Mikhail Chapochnikov, Claude Becker, Alexey Boyarsky, Oleg Ruchayskiy, Matthieu Schaller

The diversity of structures in the Universe (from the smallest galaxies to the largest superclusters) has formed under the pull of gravity from the tiny primordial perturbations that we see imprinted in the cosmic microwave background. A quantitative descr ...

Oxford Univ Press2014