Publications by Mikhail Chapochnikov

Installation and performance of the 3rd Veto plane at the SND@LHC detector

Aurelio Bay, Mikhail Chapochnikov, Olivier Schneider, Lesya Shchutska, Anna Mascellani, Carina Trippl, Elena Graverini, Ettore Zaffaroni, Jan Steggemann, Konstantin Androsov

During 2022/2023 the optimal inefficiency of the Veto system of the SND@LHC detector was measured to be (7.8 ± 2.8) × 10−8. To reduce this inefficiency, a third Veto plane was installed during the 2023-2024 Year End Technical Stop. In addition, the Veto sy ...

2025

Nonrenormalizable theories and finite formulation of QFT

Mikhail Chapochnikov

In this paper, we show how the finite formulation of quantum field theory based on Callan-Symanzik equations can be generalized to the case of nonrenormalizable theories. We derive an equation for effective action for an arbitrary single scalar field theor ...

AMER PHYSICAL SOC2025

Observation of Collider Neutrinos without Final State Muons with the SND@LHC Experiment

Aurelio Bay, Mikhail Chapochnikov, Olivier Schneider, Lesya Shchutska, Anna Mascellani, Carina Trippl, Serhii Cholak, Elena Graverini, Ettore Zaffaroni, Jan Steggemann, Konstantin Androsov, Zhenyu Yang

We report the observation of neutrino interactions without final state muons at the LHC, with a significance of 6.4σ. A dataset of proton-proton collisions at s=13.6 TeV collected by SND@LHC in 2022 and 2023 is used, corresponding to an integrated luminosi ...

American Physical Society (APS)2025

Sterile neutrinos as dark matter

Mikhail Chapochnikov

I describe the sterile neutrino dark matter candidate and discuss how it may fit into the overall picture of physics beyond the Standard Model. ...

Elsevier2024

Cosmic Matter-Antimatter Separation and Sterile Neutrino Dark Matter

Mikhail Chapochnikov

The lattice studies provided evidence of a smooth crossover between the hadronic and quark-gluon phases at high temperatures and zero chemical potential for baryonic number. We argue that these simulations may not rule out relatively weekly first-order pha ...

Sissa Medialab Srl2024

Sterile neutrino dark matter, matter-antimatter separation, and the QCD phase transition

Mikhail Chapochnikov

The Universe may contain sufficiently small size matter-antimatter domains at temperatures of a few hundred MeV, without violating the success of big bang nucleosynthesis. We demonstrate that this possibility enhances the keV scale sterile neutrino product ...

American Physical Society2024

Measurement of the muon flux at the SND@LHC experiment

Aurelio Bay, Mikhail Chapochnikov, Guido Haefeli, Olivier Schneider, Lesya Shchutska, Anna Mascellani, Carina Trippl, Serhii Cholak, Elena Graverini, Ettore Zaffaroni

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 ...

2024

Results and Perspectives from the First Two Years of Neutrino Physics at the LHC by the SND@LHC Experiment

Aurelio Bay, Mikhail Chapochnikov, Guido Haefeli, Olivier Schneider, Sun Hee Kim, Lesya Shchutska, Inar Timiryasov, Anna Mascellani, Carina Trippl, Serhii Cholak, Elena Graverini, Ettore Zaffaroni, Jan Steggemann, Konstantin Androsov

After rapid approval and installation, the SND@LHC Collaboration was able to gather data successfully in 2022 and 2023. Neutrino interactions from nu(mu)s originating at the LHC IP1 were observed. Since muons constitute the major background for neutrino in ...

MDPI2024

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

Mikhail Chapochnikov, Alexandre Emmanuel Grandchamp, Lesya Shchutska, Inar Timiryasov, Maria Elena Stramaglia, Ana Bárbara Rodrigues Cavalcante, Federico Leo Redi, Elena Graverini

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 ...

2024

Weyl-invariant Einstein-Cartan gravity: unifying the strong CP and hierarchy puzzles

Mikhail Chapochnikov

We show that the minimal Weyl-invariant Einstein-Cartan gravity in combination with the Standard Model of particle physics contains just one extra scalar degree of freedom (in addition to the graviton and the Standard Model fields) with the properties of a ...

Springer Nature2024

Non-polynomial interactions as a path towards a non-renormalizable UV-completion

Mikhail Chapochnikov

We propose a new class of single-field scalar quantum field theories with non-polynomial interactions leading to a two-point Green's function that can be naturally continued beyond the naive cutoff scale. This provides a new prospect for self-completing th ...

2024

Effective potential in finite formulation of QFT

Mikhail Chapochnikov, Sander Johannes Nicolaas Mooij

In recent works [1,2], we have shown how n-point correlation functions in perturbative QFT can be computed without running into intermediate divergences. Here we want to illustrate explicitly that one can calculate the quantum effective potential by the sa ...

2024

QFT without infinities and hierarchy problem

Mikhail Chapochnikov, Sander Johannes Nicolaas Mooij

The standard way to do computations in Quantum Field Theory (QFT) often results in the requirement of dramatic cancellations between contributions induced by a "heavy" sector into the physical observables of the "light" (or low energy) sector - the phenome ...

ELSEVIER2023

Scale invariant Einstein-Cartan gravity and flat space conformal symmetry

Mikhail Chapochnikov, Georgios Karananas, Sebastian Zell

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 ...

Springer Nature2023

Anomaly-free scale symmetry and gravity

Mikhail Chapochnikov, Anna Tokareva

In this Letter, we address the question of whether the conformal invariance can be considered as a global symmetry of a theory of fundamental interactions. To describe Nature, this theory must contain a mechanism of spontaneous breaking of the scale symmet ...

ELSEVIER2023

Finite Callan-Symanzik renormalisation for multiple scalar fields

Mikhail Chapochnikov, Sander Johannes Nicolaas Mooij

We study a finite, divergence-free approach to renormalisation originally proposed in the early '70s by Blaer and Young, and Callan. It is based on equations similar to the Callan-Symanzik equations and introduced in the context of the & lambda;& phi;4 the ...

ELSEVIER2023

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

Mikhail Chapochnikov, Anna Tokareva

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 ...

American Physical Society2023

Track reconstruction and matching between emulsion and silicon pixel detectors for the SHiP-charm experiment

Aurelio Bay, Mikhail Chapochnikov, Guido Haefeli, Alexandre Emmanuel Grandchamp, Lesya Shchutska, Inar Timiryasov, Maria Elena Stramaglia, Ana Bárbara Rodrigues Cavalcante, Federico Leo Redi, Elena Graverini

In July 2018 an optimization run for the proposed charm cross section measurement for SHiP was performed at the CERN SPS. A heavy, moving target instrumented with nuclear emulsion films followed by a silicon pixel tracker was installed in front of the Goli ...

2022

Field redefinitions, perturbative unitarity and Higgs inflation

Mikhail Chapochnikov, Sebastian Zell

For inflation driven by the Higgs field coupled non-minimally to gravity, we study the cutoff energy scale above which perturbation theory breaks down. Employing the metric formulation, we first give an overview of known results and then provide a new way ...

Springer Nature2022

Freeze-in and freeze-out generation of lepton asymmetries after baryogenesis in the nu MSM

Mikhail Chapochnikov, Shintaro Eijima, Inar Timiryasov

The nu MSM an extension of the Standard Model by three relatively light singlet Majorana fermions N-1,N-2,N-3 allows for the generation of lepton asymmetry which is several orders of magnitude larger than the observed baryon asymmetry of the Universe. The ...

IOP Publishing Ltd2022