# Moscow International School of Physics 2020

Europe/Moscow
HSE Study Center “Voronovo”

#### HSE Study Center “Voronovo”

Voronovskoe, Moscow Russian Federation
Description

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Organizing Committee
• Tuesday, 3 March
• 11:00 11:30
Arrival 30m
• 11:30 12:30
Registration 1h
• 12:30 13:30
Lunch 1h
• 14:00 15:00
Flavor Physics: part 1 1h
Speaker: Monica Pepe Altarelli (CERN)
• 15:00 16:00
Machine Learning for Physicists: part 1 1h
Speaker: Andrey Ustyuzhanin (NRU HSE)
• 16:00 16:30
Coffee Break 30m
• 16:30 17:30
Machine Learning for Physicists: part 2 1h
Speaker: Andrey Ustyuzhanin (NRU HSE)
• 17:30 18:30
Young Scientist Forum
• 17:30
Studying the CP nature of the Top-Yukawa coupling 12m

The analysis presented studies the production of a Higgs boson via gluon fusion in association with 2 jets with the aim of setting constraints on the CP properties of the top-Yukawa coupling. According to the SM, the Higgs boson must to be a CP even scalar, however some Beyond Standard Model theories predict the existence of the superposition of CP eigenstates, resulting in a CP mixed state. The distribution of the azimuthal angle between the two jets produced in association with the Higgs boson in the gluon fusion process is directly correlated with its CP properties and is therefore used to investigate the top-Yukawa coupling. Results based on the analysis of the Run-2 dataset collected with the ATLAS experiment at a center-of-mass of 13 TeV will be presented.

Speaker: Federica Pasquali (Nikhef)
• 17:42
Measurement of the CP violation in Bs->Jpsi+Phi decays in ATLAS at 13 TeV 12m

A measurement of the $B_{s} \to J/\psi\phi$ decay parameters using 80.5 fb$^{-1}$  of integrated luminosity collected with the ATLAS detector from 13 TeV pp collisions at the LHC is presented. The measured parameters include the CP-violating phase $ϕ_{s}$.

Speaker: Oleg Meshkov (Lomonosov MSU, P.N. Lebedev Physical Institute)
• 17:54
Observation of the Lambda_b -> J/psi Lambda phi decay 12m

The observation of the $\Lambda_b^0\rightarrow J/\psi\Lambda\phi$ decay is reported using proton-proton collision data collected at $\sqrt{s} = 13$ TeV by the CMS experiment at the LHC in 2018, corresponding to an integrated luminosity of 60 $fb^{-1}$. The ratio of branching fractions $B(\Lambda_b^0\rightarrow J/\psi\Lambda\phi)/B(\Lambda_b^0\rightarrow \psi(2S)\Lambda)$ is measured to be $(8.26 \pm 0.90(stat) \pm 0.68(syst) \pm 0.11(B)) \times 10^{-2}$, where the first uncertainty is statistical, the second is systematic, and the last uncertainty reflects the uncertainties in the world-average branching fractions of $\phi$ and $\psi(2S)$ decays to the reconstructed final states.

Speaker: Nikita Petrov
• 18:06
Numerical study of multiparticle probabilities in the λϕ4 theory 12m

The talk is aimed at giving insights from the ongoing research into multiparticle scattering in the real scalar field theory. The object of the research is the unbroken $\lambda \phi^4$ theory in the case of weak coupling. The research aims are to obtain semiclassical suppression exponents for the processes few $\to N$, where $N$ is a semiclassically large ($\sim 1/\lambda$) final number of particles, and "few" is a few-particle initial state.

Since in the semiclassical limit solutions of the saddle-point equations (which replace classical field equations in semiclassics) become singular for considered boundary value problem (they have a discontinuity in the energy), this singular behaviour can be represented through the term with a delta-like source $j$ in the action. In this approach, properties of the saddle-point solutions are recovered in the limit $j\to 0$. In our research, we start from source-dominated solutions which we can describe analytically and then take the limit $j\to 0$ by solving lattice saddle-point equations with Newton-Raphson method for every new smaller amplitude of the source, step by step.

During the talk, I would like to describe our research and show the first obtained results.

Speaker: Mr Bulat Farkhtdinov (MIPT(SU), INR)
• 18:18
Study of excited Lambda_b baryons at the CMS experiment 12m

The study of excited $\Lambda_{\mathrm{b}}^0$ baryons is reported, based on a data sample of $140$\,fb$^{-1}$ collected with the CMS detector in proton-proton collision at centre-of-mass energy of 13 TeV. Existence of four baryon states $\Lambda_{\mathrm{b}}^*(5912)^0$, $\Lambda_{\mathrm{b}}^*(5920)^0$, $\Lambda_{\mathrm{b}}^*(6146)^0$, and $\Lambda_{\mathrm{b}}^*(6152)^0$ is confirmed and their masses are measured.

Speaker: Sergey Polikarpov (NRNU MEPhI, LPI RAS)
• 19:00 20:00
Dinner 1h
• 20:00 22:00
Seminar

A laptop able to run Python notebooks (Python + Jupyter Notebook + PyTorch) is required.

Convener: Andrey Ustyuzhanin (NRU HSE)
• Wednesday, 4 March
• 08:00 09:00
Breakfast 1h
• 09:00 10:00
Black Holes and Gravitational Waves: part 1 1h
Speaker: Konstantin Postnov (Sternberg Astronomical Institute)
• 10:00 11:00
Flavor Physics: part 2 1h
Speaker: Monica Pepe Altarelli (CERN)
• 11:00 13:30
Ski & Outdoors 2h 30m
• 13:30 14:30
Lunch 1h
• 16:00 16:30
Coffee Break 30m
• 17:30 18:30
Machine Learning for Physicists: part 3 1h
Speaker: Andrey Ustyuzhanin (NRU HSE)
• 19:00 20:00
Dinner 1h
• 20:00 22:00
Seminar

A laptop able to run Python notebooks (Python + Jupyter Notebook + PyTorch) is required.

Convener: Andrey Ustyuzhanin (NRU HSE)
• Thursday, 5 March
• 08:00 09:00
Breakfast 1h
• 09:00 10:00
Black Holes and Gravitational Waves: part 2 1h
Speaker: Konstantin Postnov (Sternberg Astronomical Institute)
• 10:00 11:00
Flavor Physics: part 3 1h
Speaker: Monica Pepe Altarelli (CERN)
• 11:00 13:30
Ski & Outdoors 2h 30m
• 13:30 14:30
Lunch 1h
• 16:00 16:30
Coffee Break 30m
• 17:30 18:30
Young Scientist Forum
• 17:30
Light scalar dark matter coupled to a trace of energy-momentum tensor 12m

We consider dark matter represented by the light scalar field whose coupling to the ordinary matter is extremely suppressed. We assume that this interaction can be described as the coupling of the square of the field to the energy-momentum tensor. We study the effect of this interaction on the evolution of dark matter scalar, as well as bounds on the model parameters that come from the variation of fundamental constants at the BBN.

Speaker: Mr Aleksandr Belokon (Institute for Nuclear Research of Russian Academy of Science)
• 17:42
Partial Wave Analysis of pbarp->phiphi at PANDA 12m

The $\overline{\text{P}}\text{ANDA}$ experiment at FAIR in Darmstadt (Germany), which is currently under construction, will provide excellent opportunities to search for exotic states in anitproton-proton annihilations. Various experiments observed tensor resonances in the $\phi\phi$ system in the same mass region where Lattice QCD calculations predict the tensor glueball. The determined magnitude of the reaction exceeds expectations from a simple application of the OZI rule by two orders of magnitude, which was interpreted as a hint for a possible intermediate glueball state. Therefore, the reaction $\overline{p}p\rightarrow\phi\phi$ is considered to offer a gluonrich environment and will be studied at ${\overline{\text{P}}}\text{ANDA}$ by performing an energy scan at center of mass energies between about 2.25 GeV and 2.6 GeV. Contributing resonances in the $\phi\phi$ system can then be identified by means of a mass independent partial wave analysis. In this contribution, studies will be presented that have been carried out in order to address the feasibility to identify contributing resonances produced in this formation process, utilizing the partial wave analysis software PAWIAN.

Speaker: Iman Keshk
• 17:54
Light sgoldstinos and Higgs sector in the supersymmetric extension of the Standard Model 12m

We consider a supersymmetric extension of the Standard Model with a broken supersymmetry. Our model contains the fields of the Minimal Supersymmetric Standard Model and goldstino multiplet, which is present due to the supersymmetric version of the Goldstone theorem. Scalar component of this multiplet is traditionally called sgoldstino. We consider the interval of sgoldstino masses from 260 GeV to 1 TeV.
We investigate the possibility of increase in resonant di-Higgs production cross section at the LHC energies due to processes with sgoldstino. Sgoldstino is an R-even particle and thus it can be produced by the gluon fusion and then decay into the pairs of the Standard Model particles, for instance, the pairs of light neutral Higgs bosons.
We show that there are two typical behaviors of sgoldstino branching ratio: gluon domination and the major decay to pairs of light neutral Higgses, W-bosons and Z-bosons. We estimate the borders of the corresponding regions in the parameter space. For particular values of sgoldstino-Higgs mixing angles we obtain an upper limit for the ratio $M_3/F$ from experimental searches for heavy scalar resonances made by the ATLAS and the CMS collaborations.

Speaker: Ekaterina Kriukova (MSU, INR RAS)
• 18:06
Search for electroweak production of charginos and sleptons decaying into final states with two leptons and missing transverse momentum at Run 2 with the ATLAS detector 12m

Recent results from a search for the electroweak production of charginos and sleptons decaying into final states with two leptons (electrons and/or muons) are presented on 139 $\text{fb}^{-1}$ proton-proton collision data recorded by the ATLAS detector at the Large Hadron Collider at $\sqrt{s} = 13$ TeV. Three different R-parity conserving scenarios, based on simplified models, are considered: the direct production of lightest chargino pairs, followed by their decays into final states with leptons and the lightest neutralino via either W bosons or sleptons/sneutrinos; the direct production of slepton pairs, where each slepton decays into the lightest neutralino and a lepton. No significant deviations from the Standard Model expectations are observed and limits at 95% confidence level are set on the masses of the relevant supersymmetric particles in each of these scenarios.

Speaker: Francesco Giuseppe Gravili (INFN Lecce e Universita del Salento (IT))
• 19:00 20:00
Dinner 1h
• 20:00 22:00
Poster Session
• 20:00
Development of a method for reweighting distributions to search for new physics using effective field theory 12m

It is conveniently to use a model-independent approach of effective field theory for indirect search of new physics. This approach consists of parametrization of the lagrangian with operators of higher dimensons with some coefficients. If we compare experimental data with Monte Carlo results, it becomes possible to impose an upper limit of the value of coefficients. However, the real value of any coefficient belongs to a continuous spectrum, whereas Monte Carlo modeling can be performed for discrete set of the values of coefficients. In this work the problem of reweighting of kinematic distributions was considered. There was developed a method to get distributions for any value of coefficient using initial distributions, obtained with fixed coefficient value. This method will be employed to get constraints on the values of coefficients.

Speaker: Artur Semushin
• 20:12
Using of neural network technology for improvement of energy resolution of highly granular hadron calorimeter 12m

The technology of highly granular calorimeters is one of the innovations that will be implemented in the planned accelerator experiments, for example in the future linear collider. The work is devoted to the study of hadronic showers in the highly granular hadron calorimeter of the ILD detector and the application of machine learning to the improvement of the energy resolution. The artificial neural network was built, the dependencies between the selected input variables were studied. The study was performed using the simulation of single hadrons with energies from 5 to 60 GeV in the ILD detector.

Speaker: Sergey Korpachev
• 20:24
On quantization in background scalar fields 12m

We consider (0+1) and (1+1) dimensional Yukawa theory in various scalar field backgrounds, which are solving classical equations of motion. The (0+1)–dimensional theory we solve exactly. In (1+1)–dimensions we consider background fields of the form $\phi_{cl} = Et$ and $\phi_{cl} = Ex$, which are inspired by the constant electric field. Here E is a constant. We study the backreaction problem by various methods, including the dynamics of a coherent state. We also calculate loop corrections to the correlation functions in the theory using the Schwinger–Keldysh diagrammatic technique.

Speaker: Dmitrii Trunin (MIPT & ITEP)
• 20:36
Neutron from cosmic muons background simulation in DANSS experiment 12m

The DANSS experiment aims to search for sterile neutrinos. It is a compact neutrino spectrometer located at the Kalinin Nuclear Power Plant close to the core of the industrial power reactor. The detector records about 3000-4000 events per day after subtracting the background depending on the position. The significant contribution to background events is made by neutrons from the interaction of cosmic muons formed in the materials surrounding the detector volume. In this work preliminary results of neutron signal spectra are presented.

Speaker: Mrs Anna Ershova (MIPT, ITEP)
• 20:48
DsTau (NA65): Study of tau neutrino production at the CERN-SPS 12m

The uncertainty in tau neutrino production in high energy proton interactions has been the largest uncertainty in current and future tau neutrino measurements, preventing a precise test of lepton universality in neutrino scattering. DsTau (NA65) at the CERN-SPS is a recently approved experiment, which aims to study the problematic tau neutrino production. The main source of tau neutrino production is through the decay of Ds mesons, namely $D_s \rightarrow \tau \nu_\tau$ and then $\tau \rightarrow \nu_\tau X$. There is no data on the differential production cross section of Ds in proton-nucleus interactions, which leads to a large uncertainty of tau neutrino cross section measurements. DsTau addresses this issue and will provide essential inputs for future tau neutrino experiments. A large amount of charmed particles decay events ($\sim 10^5$) is expected to be detected as well, providing a possibility for interesting by-product studies, in particular a search for intrinsic charm in a proton. The experimental method is based on a use of high resolution emulsion detectors for effective registration of events with short lived particle decays. Here I present the motivation of the study, details of the experimental technique and the first results of the analysis of the data collected during test runs.

Speaker: Ms Elizaveta Sitnikova (JINR)
• 21:00
Geant4 simulation as part of luminometer development for CMS at HL-LHC 12m

Luminosity is one of the main characteristics of an accelerator. It determines the number of colliding particle (e.g. protons) interactions in a bunch crossing. The task of luminosity measurements in two-beam experiments is challenging. It becomes harder with the LHC upgrade – High-Luminosity LHC – with even higher energies, luminosity and a complex time structure of the beam. The proposed luminometer is being designed to perform online bunch-by-bunch luminosity measurements with the frequency of 25 ns, the accuracy of 1% and the ability to withstand high radiation. The proposed for this task radiation hard quartz fibers are simulated using Geant4: the physics, geometry and optical parameters are varied to optimize the accuracy of the processes of emission, capturing and transportation of Cherenkov light.

Speaker: Daria Selivanova
• 21:12
Radiative recoil corrections to the hyperfine splitting of light muonic atoms 12m

Nuclear radiative recoil corrections of order \alpha(Z*\alpha)^5 to the hyperfine structure of S-states in light muonic atoms are calculated in the framework of quasipotential method in quantum electrodynamics. Separate expressions for the contributions of the muon self-energy, muon vertex operator and the amplitude with spanning photon are obtained. For the radiative photon, we use the Fried-Yennie gauge. Numerical values of these corrections improve the accuracy of previous calculations and should be taken into account when comparing with experimental data.

Speaker: Fedor Martynenko (Samara university)
• 21:24
Calibration of SiPM-based Neutron Monitors for CMS Experiment 12m

Development of a distributed system of the neutron monitors is required to estimate the neutron spectra and monitor the neutron fields in the CMS experimental cavern. The proposed neutron monitor is based on the 6Li-enriched scintillator coupled to SiPM. During LHC Run 2, several monitor samples were successfully commissioned at the CERN laboratory and tested in CMS environment with the set of Bonner spheres. To rescale collected data to the absolute value of the neutron flux the same SiPM-based monitor samples with the set of Bonner spheres were calibrated at the CERN Radiation Protection calibration facility using Am-Be source. Afterwards, monitor readings measured in the CMS radiation field can be deconvoluted to the neutron spectrum by means of the unfolding procedure.

Speaker: Oksana Bychkova (NRNU MEPhI)
• 21:36
Superfield realization of hidden R-symmetry in extended supersymmetric gauge theories and its applications 12m

An object of the crucial importance in quantum field theory is the effective action. By definition, it is a generating functional for one-particle irreducible Green's functions, which contains complete information about the quantum properties of this model. To find an effective action, it is convenient to use the technique of harmonic superspace.

Superspace[1] is a generalization of Minkowski space and allows explicitly and in a simple form to implement supersymmetry transformations. In theories with extended supersymmetry, the concept of harmonic superspace[2] plays an important role, which allows one to realize the symmetries of the theory off shell. Its important property is the presence of an analytic subspace invariant with respect to supersymmetry.

When studying $4D, \mathcal N = 4$, and $5D, \mathcal N = 2$ of supersymmetric Yang-Mills theories in harmonic superspace, some of the transformations of supersymmetry and, accordingly, $R$-symmetry are realized hiddenly[3,4]. The standard approach for obtaining low-energy effective action is as follows[4,5]. First, the leading one-loop quantum corrections for to the effective actions of $4D, \mathcal N = 2$ and $5D, \mathcal N = 1$ SYM theories are calculated. Then, by calculating the expansion of this contribution with respect to hidden supersymmetry, expression is obtained for the effective action for $4D, \mathcal N = 4$, and $5D, \mathcal N = 2$ theories, respectively.

In this paper, a different approach is used. The hidden $R$-symmetry transformations was found. Then, by calculating the expansion of the leading term with respect to $R$-symmetry, the expression for the effective action was obtained. This procedure was applied for $4D, \mathcal N = 4$ and $5D, \mathcal N = 2$ SYM theories. The nontrivial result is that the effective action is not only $R$-symmetric invariant, but can also be obtained from the requirement of the presence of $R$-symmetry.

It is expected that this approach may be useful in the study of other supersymmetric theories, for example, $6D, \mathcal N=(2,0)$ SYM theory.

This reseerch based on the parer[6].

References
1. I. L. Buchbinder, S. M. Kuzenko. Ideas and Methods of Supersymmetry and Supergravity or a Walk
through Superspace// (IOP, Bristol, UK, 1995).
2. A.S. Galperin, E.A. Ivanov, V.I. Ogievetsky, E.S. Sokatchev. Harmonic superspace//Cambridge, UK: Univ. Pr. (2001)
3. I.L. Buchbinder, E.A. Ivanov , I.B. Samsonov. Low-energy effective action in 5D, N=2
supersymmetric gauge theory//Nucl. Phys. B 940 (2019) 54–62
4. I. L. Buchbinder, E. A. Ivanov, I. B. Samsonov. The Low-Energy N=4 SYM Effective Action in Diverse Harmonic Superspaces// Phys. Part. Nucl. 48 (3) (2017) 333
5. I. L. Buchbinder and E. A. Ivanov. Complete N = 4 structure of low-energy effective action in N = 4 super Yang-Mills theories// Phys. Lett. B 524, 208 (2002)
6. I.L. Buchbinder, E.A. Ivanov, V.A. Ivanovskiy. Superfield realization of hidden R-symmetry in extended supersymmetric gauge theories and its applications. arXiv:2001.01649 [hep-th]

Speaker: Viacheslav Ivanovskiy (MIPT)
• 21:48
A new QFT description of finite duration processes 12m

Currently the phenomena of neutrino and neutral kaon oscillations, which take place at finite space-time intervals, are usually described in the framework of approaches that are inconsistent or not convenient for describing such processes. We develop a new QFT approach, adjusting the standard S-matrix formalism for the case. One applies the usual Feynman rules in the coordinate representation to construct the amplitude of the process and then passes to the momentum representation in a way which reflects the experimental setting. Effectively, it leads to the Feynman propagator in the momentum representation being modified, while all the other Feynman rules in this representation are kept intact. Wave packets are not employed, we work in the plane wave approximation, which simplifies the calculations considerably. The novel approach allows one to consistently describe unstable particle displaced decay and particle oscillation processes and to successfully reproduce the well-known results.

• 21:48
Electromagnetic Stress-Energy tensor in a dispersive medium 12m

The main purpose of this work is to obtain the Electromagnetic Stress-Energy Tensor in a medium for a nonlocal theory. In order to get it, we generalise Minkowski electrodynamics to dispersive media. As a consequence of this generalisation, the Lagrangian density becomes non-local due to the non-local dependencies of the magnetic permeability and electric permittivity. This leads a convolution product in the Lagrangian where the field at point 'x' depends on the values of the field at any point in spacetime. Then, we derive the field equations and, applying the Noether's theorem, the conserved energy-momentum tensor. Because non-local Lagrangians are seldom found in textbooks, we devote a non-local formalism to outline the derivation of the field equations and Noether's theorem. For that, the procedure is the following: First, the non-local Lagrangian is converted into an infinite order Lagrangian (that depends on derivatives of the field of any order). Then, the equations of motion and Noether's theorem are derived as though it was an order-n Lagrangian. Finally, we extend n to infinite and the outcomes that appear contain formal series that can be summed by the techniques that we have developed. To conclude, we study the obtained Belinfante Stress-Energy Tensor for plane wave solutions for a dispersive medium.

Speaker: Mr Carlos Heredia Pimienta (University of Barcelona)
• 21:48
Generalized unimodular gravity: cospological applications and renormalizeability 12m

The recently suggested generalized unimodular gravity theory, which was originally put forward as a model of dark energy, can serve as a model of cosmological inflation driven by the effective perfect fluid—the dark purely gravitational sector of the theory. Its excitations are scalar gravitons that can generate, in the domain free from ghost and gradient instabilities, the red tilted primordial power spectrum of cosmic microwave background (CMB) perturbations matching with observations. The reconstruction of the parametric dependence of the action of the theory in the early inflationary universe is qualitatively sketched from the cosmological data and satisfies the naturalness criterion—the O(1) magnitude of all its parameters. In particular, the only phenomenological exponentially big parameter—the e-folding factor with N∼60, leads in this model to a specific expression for tensor-to-scalar ratio r ≃ 0.004, matching with the existing observational bounds on r and the CMB spectral index. The alternative possibilities of generating the cosmological acceleration and possibility of generalized renormalizeability of the theory are also discussed.

Speaker: Nikita Kolganov (MIPT and BLTP JINR)
• 21:48
Loop corrections in Schwarzschild black hole background 12m

When quantizing theory in curved space-time, one can define vacuum state with respect to different timelike Killing vectors. In case of Schwarzschild space-time one usually considers Boulware, Unruh and Hartle-Hawking vacua, where the latter two use Kruskal null coordinates to define positive-frequency modes. Loop corrections to the occupation numbers and anomalous quantum averages are considered for scalar particles and it is shown that there are no corrections up to second order in coupling constant for Boulware and Hartle-Hawking vacua, but there are non-zero contributions in case of Unruh vacuum.

Speaker: Prokopy Anempodistov (ITEP, NRNU MEPhI)
• 21:48
Notes on quantum fields in Static patch of de Sitter space 12m

We show the explicit mode expansion of tree-level propagators in Static (or Compact) Patch of de Sitter space. We construct propagator for thermal state corresponding to arbitrary temperature $T$. We show that the propagator that respects the de Sitter isometry corresponds to the thermal state with $T = (2 \pi)^{-1}$ in the units of de Sitter curvature. Which confirms the old and well known result, making it a bit more explicit. Propagators with $T\ne(2\pi)^{-1}$ do not respect the isometry. Moreover, we show that propagators with $T \neq (2 \pi)^{-1}$ have extra singularities on the boundary of the Static Patch, as opposed to the case of $T = (2 \pi)^{-1}$. We discuss physical meaning of these observations.
We also discuss loop corrections to the propagators in the Static patch and their physical meaning both for $T = (2 \pi)^{-1}$ and $T \neq (2 \pi)^{-1}$.

Speaker: Kirill Bazarov (MIPT)
• 21:48
Quantum decoherence during inflation 12m

During inflation the universe rapidly expands and the observed classical distribution of inhomogeneities originates from the substantially non-classical state. The problem of transition from quantum to classical behavior is also important outside the cosmological context in connection with the study of mesoscopic systems. And this problem can be viewed in the context of the theory of decoherence induced by environment. In short, this phenomenon lies in the fact that the quantum degrees of freedom of the system are entangled with the degrees of freedom of the environment, which leads to the suppression of interference effects and the classicalisation of the system.
In cosmological context, the transition to classical behavior is studied within the Wheeler-DeWitt approach with small inhomogeneous perturbations considered over quantized homogeneous background. The Wheeler-DeWitt equation is solved in the Born-Oppenheimer approximation. Using this approximation, one can represent the wave function as a product of homogeneous and inhomogeneous parts. Inhomogeneous wave function is associated with QFT approach on a clas-sical curved background and homogeneous part provides probability amplitude for different backgrounds. The decoherence process itself is observed by studying the corresponding density matrix.
In this paper we discuss the decoherence of background degrees of freedom due to the loss of information about modes going beyond the cosmological horizon while mantaining the full information about the short wavelength perturbations. We demonstrate the classicalization process of the quantum state of inhomogeneities of the universe by observing reduced density matrix of the short wavelength fluctuations.

Speaker: Arina Shtennikova
• 21:48

The lead tungstate crystal (PbWO4, PWO) is one of the widely used scintillation materials for electromagnetic calorimeters in high energy physics experiments. The degradation of the optical transmittance in the range of the luminescence spectrum under ionizing radiation leads to losses of the light output resulting in the deterioration of the energy resolution and limiting the life time of the calorimeter. A possible way to restore radiation damage is the in-situ illumination of visible or near infrared light of the whole crystal volume. It allows to recover the transmittance losses due to the depopulation of the color centers. Such kind of stimulated recovery subsystem based on a blue light emitting diode is considered for the electromagnetic calorimeter of the PANDA detector at FAIR (Darmstadt, Germany). Here we report on the stimulated recovery studies of the lead tungstate radiation damage induced by external light from laser diodes at different wavelengths. The level of technological development of laser diodes allows to increase the efficiency of the stimulated recovery.

Speaker: Pavel Orsich (Justus Liebig University)
• 21:48
The status of the large-scale coordinate-tracking detector TREK 12m

The new large-scale coordinate-tracking detector TREK is being developed at National Research University MEPhI. The aim of the project is the solution of so-called “muon puzzle”: the unpredicted by any theory excess of high multiplicity muon bundles generated by ultra-high energy primary cosmic rays. The joint operation with Cherenkov water detector NEVOD will allow investigation specific energy deposit of quasi-parallel inclined muon bundles generated by high energy cosmic rays in 2000 m3 water volume.

The detector TREK has an area of 250 m2 and it is based on 264 multi-wire drift chambers developed at Institute of High Energy Physics for neutrino experiment at accelerator U-70. The drift chamber has size 4000×508×112 mm3. TREK will consist of 2 planes (vertical and horizontal) with 132 chambers for each. The total area of installation is about 250 m2.

The drift chambers were tested with a joint operation with muon hodoscope URAGAN. Two prototypes of TREK were constructed, their operation demonstrated high efficiency of application of such gaseous detectors for cosmic ray investigations. The experiments on URAGAN has allowed us to investigate drift chamber work in different positions, CTUDC has allowed to test joint work of chambers with NEVOD and prototype of TREK has allowed to test multiparticle event reconstruction taking into account the relative location of chambers as in TREK installation.

Three reconstruction methods of multiparticle events have been developed. The methods have been tested on experimental data of CTUDC and prototype of TREK. A new reconstruction method based on deep learning is being developed. Also a time-digital converter based on FPGA Altera Cyclone V is being developed for TREK installation. The report describes the current status of detector TREK.

• Friday, 6 March
• 08:00 09:00
Breakfast 1h
• 09:00 10:00
Black Holes and Gravitational Waves: part 3 1h
Speaker: Konstantin Postnov (Sternberg Astronomical Institute)
• 10:00 11:00
Physics beyond the Standard Model: part 1 1h
Speaker: Riccardo Rattazzi (EPFL)
• 11:00 13:30
Ski & Outdoors 2h 30m
• 13:30 14:30
Lunch 1h
• 15:00 16:00
Neutrino Physics: part 1 1h
Speaker: Prof. Evgeny Akhmedov (Max-Planck-Insitiut fuer Kernphysik, Heidelberg)
• 16:00 16:30
Coffee Break 30m
• 16:30 17:30
The Standard Cosmological Model: part 1 1h
Speaker: Alexander Vikman
• 17:30 18:30
Young Scientist Forum
• 17:30
Decays-in-flight muon polarization measurement to extract the Michel parameter $\xi'$ in $\tau$-decays at the Future Super charm-tau Factory. 12m

We present a feasibility study of the muon polarization measurement to extract the Michel parameter $\xi'$ in $\tau$-decays. We suggest as a method using the angular distribution of an electron in the rest frame of a decayed in the drift chamber muon, as electron momentum correlates with muon polarization. The Monte Carlo simulation of the Belle detector with parameters of the Future Super charm-tau Factory beams was used to generate signal events. The possible background was studied and methods of its suppression were suggested. The most contribution is expected from the light mesons decays-in-flight and particles scattering. The reconstruction efficiency and statistical uncertainties were estimated.

Speaker: Denis Bodrov (Moscow Institute of Physics and Technology (MIPT))
• 17:42
Study of Xi_b^- signal and its excitations on LHC data 12m

$\text{A study of }\Xi_b^- \text{ baryon and its excited state }\Xi_b^{*0} \text{ is reported using proton-proton collisions}$ data sample collected at $\sqrt{s} = 13$ TeV by the CMS experiment at the LHC in 2016-2018, corresponding to an integrated luminosity of $140 \; fb^{-1}$. $\Xi_b^-$ is reconstructed in $J/\psi \Xi^-$ channel $(J/\psi \longrightarrow \mu^+ \mu^-, \Xi^- \longrightarrow \Lambda \pi^-, \Lambda \longrightarrow p \pi^-$), and its excited state studied through decay to $\Xi_b^- \pi^+$, where pion is taken from primary vertex. More than 1000 signal events of $\Xi_b^-$ and up to 90 of $\Xi_b*^0$ are obtained, that are planned to be used for further search of new $\Xi_b$ states in $\Xi_b^- \pi^+$ and $\Xi_b^- \pi^+ \pi^-$ systems.

Speaker: Mr Kirill Ivanov (MIPT)
• 17:54
Measurement of charged-particle multiplicities in jets and gluon jet fractions for jet samples selected in dijet channel produced in pp-collisions at √𝑠 = 13 TeV with the CMS detector (Run-II) 12m

The subject of the study is the measurement of the properties of the jets selected by the CMS detector in 2016 at a collision energy of 13 TeV with an integrated luminosity of 36 fb^-1. The jets were selected in events with two oppositely directed jets (dijet channel). Three samples of jets were used in the study: from events without additional jets, from events with one or two additional jets, and from events with more than two additional jets. The samples are divided into subsamples of the jets in bins according to the transverse momentum of the jet in the range from 30 to 1000 GeV. The bin size is 30 GeV.
The goal of the study is to measure the average charged-particle multiplicity and the fraction of gluon jets in the samples, depending on the average transverse momentum of the jet.
In the work, the average charged-particle multiplicity was measured for jets with cutting off low-energy tracks (less than 500 MeV). The corrections were made: (1) the contribution of the pile up jets was subtracted, (2) the correction for low-energy tracks and tracks outside the tracker, (3) jet energy correction, (4) the correction for lost and fake tracks.
The second measurement performed in the work is the measurement of the gluon jet fractions in the same samples. The quark-gluon discriminator (QGL) developed for CMS is used for this measurement. The measurement was performed by fitting the QGL distribution of jets in the data by a linear combination of QGL distributions for quark and gluon jets with one parameter — the gluon jet fraction. For fitting, the method of weighted least squares is used. Quark and gluon QGL distributions were obtained using a combination of MadGraph5 + Pythia8 generators. In this study, it was shown that independent measurements of the average charged-particle multiplicities in the jet and the gluon jet fractions are in qualitative agreement with each other for the studied jet samples.

Speaker: dzmitry budkouski
• 18:06
Title of the talk : General Treatment of Reflection of Spherical Electromagnetic Waves from the Spherical, Uneven Antarctic Surface and its Implications for the Mystery Events detected by ANITA detector. 12m

The NASA sponsored balloon-borne ANITA detector in Antarctica is designed to detect ultra high energy cosmic rays (UHECR) with energies exceeding 1 EeV ($10^{18}$ eV) by collecting the radio pulse generated through the interaction of the primary particle with Earth’s atmosphere. The radio pulse is detected after reflection from the Antarctic ice surface. For calibration and measurement of surface reflectivity, the balloon-borne HiCal radio-frequency (RF) transmitter is used. Here we are interested in determining the mean value of reflection coefficient over the range of frequencies which are of interest in HiCal observations.
We have developed a general formalism to treat reflection of spherical electromagnetic waves from a spherical surface. Our main objective is interpretation of radio wave signals produced by cosmic ray interactions with Earth’s atmosphere which are observed by the Antarctica based ANITA detector after reflection off the ice surface. The incident wave is decomposed into plane waves and each plane wave is reflected off the surface using the standard Fresnel formalism. For each plane wave the reflected wave is assumed to be locally a plane wave. This is a very reasonable assumption and there are no uncontrolled approximations in our treatment of the reflection phenomenon. The surface roughness effects are also included by using a simple model. We apply our formalism to the radiation produced by the balloon-borne HiCal radio-frequency (RF) transmitter. The final results for the reflected power are found to be in good agreement with data for all elevation angles. our framework can also handle the in-ice interaction of neutrino-induced radio signals, applicable to various neutrino detection experiments that employ the Askaryan effect. We also study the properties of reflected radio pulses in order to study their phase relationship with direct pulses. We find that for some roughness models the pulse shape can be some what distorted and may be misidentified as a direct pulse. The effect of various surface roughness models on the pulse shape will also be discussed. In this talk, I will also explain that our proposed roughness model, suitable for actual Antarctic surface topography is able to provide an explanation for the observed mystery events by ANITA.

Speaker: Ms Paramita Dasgupta (Senior Research Scholar, Department of Physics at IIT Kanpur India and Visiting Researcher in the Dept. of Physics and Astronomy at University of Kansas, Lawrence)
• 19:00 20:00
Dinner 1h
• 20:00 21:00
Seminar
Convener: Evgeny Akhmedov (Max-Planck-Insitiut fuer Kernphysik, Heidelberg)
• 21:00 22:00
Concert 1h
• Saturday, 7 March
• 08:00 09:00
Breakfast 1h
• 09:00 13:30
Excursion 4h 30m

There are two excursion options:
• guided bus tour to the Kremlin, the Saint Basil’s Cathedral and the Red Square
• guided bus tour to the Pafnutiev Abbey and the Ethnographic park-museum “Ethnomir”

• 13:30 14:30
Lunch 1h
• 14:30 19:00
Excursion 4h 30m

There are two excursion options:
• guided bus tour to the Kremlin, the Saint Basil’s Cathedral and the Red Square
• guided bus tour to the Pafnutiev Abbey and the Ethnographic park-museum “Ethnomir”

• 19:00 20:00
School Dinner 1h
• 20:00 22:00
Bonfire 2h
• Sunday, 8 March
• 08:00 09:00
Breakfast 1h
• 09:00 10:00
Black Holes and Gravitational Waves: part 4 1h
Speaker: Konstantin Postnov (Sternberg Astronomical Institute)
• 10:00 11:00
Physics beyond the Standard Model: part 2 1h
Speaker: Riccardo Rattazzi (EPFL)
• 11:00 13:30
Ski & Outdoors 2h 30m
• 13:30 14:30
Lunch 1h
• 15:00 16:00
Neutrino Physics: part 2 1h
Speaker: Evgeny Akhmedov (Max-Planck-Insitiut fuer Kernphysik, Heidelberg)
• 16:00 16:30
Coffee Break 30m
• 16:30 17:30
The Standard Cosmological Model: part 2 1h
Speaker: Alexander Vikman
• 17:30 18:30
Young Scientist Forum
• 17:30
Statistical data analysis in the DANSS experiment 12m

DANSS is a one cubic meter highly segmented solid scintillator detector. It consists of 2500 scintillator strips, covered with gadolinium loaded reflective coating and read out with SiPMs via wavelength shifting fibers. DANSS is placed under a 3 GW industrial reactor at the Kalinin NPP (Russia) on a movable platform. The distance from the reactor core center is varied from 10.7 m to 12.7 m on-line. The inverse beta decay (IBD) process is used to detect antineutrinos. DANSS detects about 4000 IBD events per day with the background from cosmic muons at the level of few percent.
Sterile neutrinos are searched for assuming a 4 neutrino model (3 active and 1 sterile neutrino). The exclusion area in the sterile neutrino parameter plane is obtained using a ratio of positron energy spectra collected at different distances. We compare the most robust analysis based on a comparison of antineutrino energy spectra shapes at different distances with the analysis that uses information about the counting rates as well. The talk will cover the analysis of systematic uncertainties and the statistical methods used to obtain exclusion areas.

Speaker: Nataliya Skrobova (LPI)
• 17:42
Studying of processes caused by stopped muons for the energy scale determination in the DANSS experiment 12m

DANSS is a one cubic meter highly segmented solid scintillator detector. It consists of 2500 scintillator strips, covered with gadolinium loaded reflective coating and read out with SiPMs and PMTs via wavelength shifting fibers. DANSS is placed under a 3 GW industrial reactor at the Kalinin NPP (Russia) on a movable platform. The inverse beta decay (IBD) process is used to detect antineutrinos. DANSS detects about 5000 IBD events per day with the background from cosmic muons at the level of a few percent. Antineutrino energies are determined from the IBD reaction by measuring energies of produced positrons, therefore the energy scale accuracy is a key parameter for the data analysis. We use two processes caused by stopped muons in order to determine the energy scale. Muon and anti-muon decays at rest provide electrons and positrons with energies up to 53 MeV. The second process is a beta decay of borum produced in stopped muon's capture on carbon: $\mu^- + \ ^{12}C \ \rightarrow \ ^{12}B + \nu_\mu$. The borum beta decay electron energy spectrum ranges up to 14 MeV. In the talk we describe a method of identification of muons stopped inside the central cube of the detector and present selection criteria for studied reactions. The measured electron and positron energy spectra from the two studied processes are compared with the results of the Monte Carlo simulations in order to determine the corrections to the energy scale and the additional blurring coefficient, required to describe the experimental data.

Speaker: Alexandra Yakovleva (Moscow Institute of Physics and Technology (State University))
• 17:54
Hadronic molecular binding of $Z_b(10610)$ and $Z_b(10650)$ 12m

Starting with the discovery of the $X(3872)$ in 2003, evidence for many exotic states beyond explanations within the quark model have been found in experiments worldwide. Many of those states are close to thresholds of two combined open-flavor states with convenient quantum numbers, such that the data suggests a treatment as a composite system, namely a hadronic molecule. In the talk, research for the case of $Z_b(10610)$ and $Z_b(10650)$ will be examined. Calculations using HQET and $\chi$PT that might disclose the molecular nature of a composite $B^{(*)}$-$\bar{B}^{(*)}$ system will be presented. The obtained matrix elements could be used for the computation of a possible molecular binding energy and the shape of the corresponding potential well which hopefully gives insight into the internal mechanism of Z-states.

Speaker: Simon Leon Krug
• 18:06
Belle II Status and Prospects 12m

At the end of 2018 the inner subdetectors, SVD (Silicon Vertex Detector) and PXD (Pixel
Detector) were installed in Belle II. By the end of 2019 Belle II has collected a total of 10 fb$^{−1}$. With
the early data taken the charged-particles tracking performance of the detector was characterized,
reconstruction of known resonances and the capability of identifying displaced vertices decays.
0
One of the first benchmarks for B physics was the measurement of the B 0 −B mixing frequency.
First results are based on the B mesons semileptonic decay mode. The rediscovery of the “golden
mode” $B^0 \rightarrow J/\psi K_{S}^{0}$, a CP eigenstate, is shown along other $B \rightarrow [c\bar{c}]X_s$ decay modes.
Prospects for dark sector searches, CPV in Charm physics and other motivations for B physics
are discussed.

Speaker: Dr Thomas Czank (IPMU)
• 19:00 20:00
Dinner 1h
• 20:00 22:00
Young Scientist Forum
• 20:00
Measurement of γ*ωπ0 form factor using SND detector on VEPP-2000 12m

The cross section $e^+e^- \to \omega\pi^0 \to \pi^+\pi^-2\pi^0$ is measured in 1 - 2 GeV c. m. energy range using statistics collected by SND detector installed on VEPP-2000 collider in experiments MHAD2011 and MHAD2012 with integrated luminosity $35\text{ pb}^{-1}$. The measured cross section is in the agreement with previous measurements but has better accuracy. $\gamma^*\omega\pi^0$ form factor is calculated from the obtained cross section and approximated using several variants of the vector meson dominance model. It is found that the model is not able to describe the form factor with sufficient accuracy in the studied energy range. The data of NA60 experiment show a noticeably faster growth of the form factor as the c. m. energy approaches the $\rho$-meson in comparison with model predictions.

Speaker: Mr V. N. Zhabin (BINP)
• 20:12
Extension of the N/D-method for $\text{K}\pi$ scattering using unitarity, $\chi$PT and resonance exchanges (consistent with chiral symmetry) to energies above 1.4 GeV 12m

The ongoing improvement of data of processes such as $B \rightarrow J/\psi ~ \text{K} ~ \pi$ containing $\text{K}\pi$ final state interactions, measured by LHCb or COMPASS, require a theoretically sound description consistent with unitarity and analyticity. The understanding of such meson-meson strong interactions is still unclear and controversial in some energy regions. In particular a lot of resonances are very broad or difficult to distinguish from background. Hence a parametrisation using standard Breit-Wigner resonances is inept. In contrast the N/D-method gives the right branch cut structure consistent with unitarity and analyticity relying on $\chi$PT and resonance exchanges consistent with chiral symmetry.
We want to present our ongoing process of expanding the area of validity for the description of $\text{K}\pi\rightarrow\text{K}\pi$ scattering amplitudes beyond 1.4 GeV using the N/D-method (as done up to 1.4 GeV [1]). The present model is enhanced by taking additionally to the $\text{K}\eta$ coupled channel the $\text{K}\eta^\prime$ into account as well as adding higher energetic resonances. Our main focus will be on $I(J^P)=\frac{1}{2}(0^+)$ s-wave amplitudes, where the $\text{K}^*_0 (700)$ (prior $\kappa$) as well as $\text{K}^*_0 (1430)$ and $\text{K}^*_0 (1950)$ are present. In the future the framework should be expanded to incorporate higher partial waves as well.

[1] J. A. Oller and E. Oset, "N/D description of two meson amplitudes and chiral
symmetry" in Phys. Rev. D60, 1999

Speakers: Frederic Noel, Leon Alexander von Detten (IAS-4 Forschungszentrum Jülich)
• 20:24
Study of the e+e- -> eta gamma process with SND detector on VEPP-2000 e+e- collider 12m

We report preliminary results for the cross section of the $e^+e^- → \eta \gamma$ process measured in the center-of-mass energy range below 1.04 GeV. The data used for the analysis were collected by the SND detector at the VEPP-2000 $e^+e^-$ collider in 2013 and 2018 with the integrated luminosity of 82 pb$^{-1}$. Kinematic reconstruction of events was performed to select the signal process. Integrated luminosity at each energy point was measured using the process $e^+e^- → \gamma \gamma$ .

Speaker: Yana Savchenko
• 20:36
Optimization of the Hyper-Kamiokande detector to increase sensitivity to low-energy neutrinos. 12m

To increase the sensitivity for detection of solar neutrinos and
Supernova relic neutrinos by the Cherenkov radiation in the
Hyper-Kamiokande detector it is proposed to use light collectors (mirrors)
surrounding PMTs. The simulation of the light collectors was done. An
increase in the efficiency of neutrino registration for different mirror
shapes and sizes was investigated, as well as negative effects associated
with the reflection of Cherenkov light.

Speaker: Anastasia Shaykina (INR RAS)
• 20:48
Monte Carlo event generators for neutrino-nucleus scattering in the few-GeV region 12m

Accelerator-based neutrino oscillation experiments rely on the description of neutrino interactions with bound nucleons inside atomic nuclei. Neutrino fluxes used in modern experiments (T2K, NOvA) are peaked in the 0.5–5 GeV energy region where one can identify contributions from multiple interaction channels and various nuclear effects. The neutrino-nucleus cross sections in this region are known with a precision not exceeding 20% and have to be investigated further in pursue to reduce systematic errors in oscillation measurements.
The concept of Monte Carlo neutrino event generators, which provide essential cross section expectations for oscillation experiments, is examplified by NuWro, the generator developed at the University of Wroclaw. I will discuss various implementations of nuclear effects on top of the factorization framework used to describe neutrino-nucleus scattering, focusing specifically on possible generator development using more sophisticated microscopic models.

Speaker: Kajetan Niewczas (University of Wrocław / Ghent University)
• 21:00
SIDIS Kaon Beam Spin Asymmetry Measurements with CLAS12 12m

In 2018 the CLAS12 detector started data taking with a polarized 10.6 GeV electron beam at Jefferson Laboratory (JLab). One of the quantities which can be extracted from the data is the moment $\mathrm{A_{LU}^{sin(\phi)}}$ corresponding to the polarized electron beam spin asymmetry in semi-inclusive deep inelastic scattering.

$\mathrm{A_{LU}^{sin(\phi)}}$ is a twist-3 quantity that provides information about the quark gluon correlations. It was studied with a 10.6 GeV longitudinally polarized electron beam and an unpolarized liquid hydrogen target.

The talk will present an analysis of meson channels over a large kinematic range with virtualities Q$^\mathrm{2}$ ranging from 1 GeV$^\mathrm{2}$ to 8 GeV$^\mathrm{2}$. The measurement in a large range of z, x$_\mathrm{B}$, p$_\mathrm{T}$ and Q$^\mathrm{2}$, including not yet measured kinematic regions, will allow a comparison with different reaction models.

Speaker: Mr Áron Kripkó (Justus Liebig Universität Gießen)
• Monday, 9 March
• 08:00 09:00
Breakfast 1h
• 09:00 10:00
Neutrino Physics: part 3 1h
Speaker: Evgeny Akhmedov (Max-Planck-Insitiut fuer Kernphysik, Heidelberg)
• 10:00 11:00
Physics beyond the Standard Model: part 3 1h
Speaker: Riccardo Rattazzi (EPFL)
• 11:00 11:30
Coffee Break 30m
• 11:30 12:30
Neutrino Physics: part 4 1h
Speaker: Evgeny Akhmedov (Max-Planck-Insitiut fuer Kernphysik, Heidelberg)
• 12:30 13:30
The Standard Cosmological Model: part 3 1h
Speaker: Alexander Vikman
• 13:30 14:30
Lunch 1h
• 15:00 15:30
Departure 30m
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