Semileptonic flavor changing neutral current transitions with a pair of neutrinos in the final state are very accurately determined in the standard model (SM) and thus provide an accurate and sensitive probe for physics beyond the SM. Until recently, the poor tagging efficiency for the B -> K(∗)νν modes made them less advantageous as a probe of new physics (NP) compared to the charged lepton...
Simulations play an important role in high energy physics. They help to optimize detectors for experiments. We present a neural-network-based algorithm for prediction of parameters of secondaries in a hadronic shower using calorimetric observables. The method proposed was tested for two hadronic models of the Geant4 package.
We investigate the free energy and entropy of the Gaussian massive scalar field theory in the static de Sitter space-time for arbitrary temperature. For the inverse temperatures of the form $\beta=2 \pi 2^k, \ \ k\in \mathbf{Z}$, in curvature units, we find the explicit form of the free energy and its derivatives with respect to the temperature. There are two types of contributions to the free...
The background induced by misidentification of a jet as a photon is usually estimated using two-dimensional sideband method (ABCD-method). This report is devoted to an alternative method of the estimation based on maximum likelihood method using RooFit toolkit. This method doesn't require optimisation of ABCD regions definition, which results in much faster estimation. One of the main...
One of conventional measures of chaotic behavior in classical Hamiltonian systems is the Lyapunov exponent. This quantity has a nonunique generalization to quantum case. Comparison of such a different generalization has a difficulty, namely, chaotic systems are nonintegrable, so that rare system can be analyzed analytically. We compute classical Lyapunov exponent numerically in the particular...
The second order phase transitions and critical phenomena are accompanied by anomalous increase of correlation radius and relaxation time. On the approach of a system to its critical point, these values are described by power law and characterized by critical exponents. These universal constants depend on the dimension of the space and the number of components of the order parameter, but...
The existence of gravitational waves is a consequence of the general theory of relativity.
Despite the fact that gravitational waves were predicted more than 50 years ago, they were measured relatively recently - in 2015 on the LIGO detector. The received signal came from the event of the merger of two black holes. The main problem in measuring such signals is their small amplitude. Therefore,...
The AdS/CFT correspondence formulated by Juan Maldacena has inspired the construction of numerous models in the theory of strong interactions, condensed matter physics and some other areas where the problem of strong coupling arises. The AdS/CFT correspondence hypothesis states, in particular, that 4-dimensional CFT in flat space in the strong-coupling regime can be described in terms of the...
The report will be devoted to the description of the N=2 theory of higher spins and their interactions with the hypermultiplet. To formulate the theory, the language of harmonic superspace is used. The structure of the corresponding N=2 supercurrents will also be discussed.
Present high energy physics experiments require specific materials and technologies. For example the LHC high luminosity phase implies significant changes for LHCb in the upcoming upgrade 2. For the calorimetry system our main activities are concentrated on the upcoming upgrade of the electromagnetic calorimeter (ECAL), with changing the inner part of the present shashlik type modules in favor...
We consider massive scalar field theory on static four-dimensional space-times with horizons. We study the near horizon behavior of the quantum expectation values of the stress--energy tensor operator for thermal state with generic temperatures. It turns out that the dependence of the expectation values on the temperature and tensor structure of the stress--energy tensor differs from the...
$\eta_c$-meson production and two-photon decay at the NICA energies was studied. Square of the amplitude of the above process was found and the signal-background ratio was constructed. The process of diphoton birth (direct and with fragmentation) was chosen as the background. Special attention was paid to the influence of experimental cut on transverse momentum on the calculation results.The...
One of the ways to detect a sterile neutrino, as well as to measure its mass and strength of connection with an ordinary neutrino, is to search for decays of heavy hadrons, in which the lepton number conservation law is violated. The report discusses the prospects for searching for a heavy sterile neutrino in the decay of a $D_s$ meson into two muons of the same sign and a pion of opposite...
We present a classification for relativistic Gaudin models on GL-bundles over elliptic curve. We describe the most general GL(NM) classical elliptic finite-dimensional integrable system, in which Lax matrix has n simple poles on elliptic curve. Also, we provide a description of this model through R-matrices satisfying associative Yang-Baxter equation. Finally, we describe the inhomogeneous...
The phenomenon of self-organized criticality (SOC) consists in the emergence of scaling in open nonequilibrium systems with dissipative transport. Unlike equilibrium systems that arrive at critical states when control parameters approach their critical values, systems with SOC evolve to critical states due to their intrinsic dynamics. Such systems are widespread in nature with SOC being...
We develop an inflationary model without small parameters on the basis of multidimensional $f(R)$ gravity with a minimally coupled scalar field. The model is described by two stages. The first one begins at energy scales about the D-dimensional Planck mass and ends with the de Sitter metric of our space and the maximally symmetric extra dimensions. In the following, the quantum fluctuations...
T violation in neutrino oscillations in vacuum is a well known fact. Due to the CPT theorem this fact is strictly connected with the CP violating phase in the neutrino mixing matrix. Since neutrino interaction with matter or external electromagnetic field violates Lorentz invariance, influence of external conditions can lead to T violation even in the model with real mixing matrix, e.g. in the...
The charm hadron production in high-energy $pp$ collisions into the forward
region ($2<\eta<5$) has been recently studied by LHCb experiment at
several centre-of-mass energies of 5, 7 and 13 TeV [1-3].
These studies were done mainly for charm mesons and there is a certain lack
of the data for baryons. Moreover, excited states were not investigated at all.
The ongoing research is devoted...
The diffuse supernova neutrino background (DSNB) is a powerful future tool to constrain core-collapse explosion mechanisms without observation of a nearby event, and the corresponding signal has been calculated for a variety of collapse models. For Supernova (SN) 1987A, a peculiar double neutrino burst was detected, but models for the double collapse have never been studied in the DSNB...
Ultra-high energy cosmic rays (UHECR) can be produced in active galaxies, and directional correlations between them were studied extensively. One puzzling result was the correlations of arrival directions of UHECR and a particular class of active galactic nuclei, BL Lacertae type objects, discovered in 2004 with the HiRes stereo data set [1,2]. If confirmed, this result would definitely mean...
The information about the fragmentation process is used to describe the dynamics of hard processes at the different parts of experimental high energy physics. The information about probability of production of a final state hadron from a parton of a specific type plays a key role in those studies. The fragmentation processes are difficult to simulate, but the information about them could be...
