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The vGeN experiment is aimed to study coherent elastic neutrino-nucleus scattering and search for neutrino electromagnetic properties. The vGeN experimental setup is located at a distance of 11 meters from the center of reactor core of Kalinin Nuclear Power Plant Unit#3. The data is taken with the high-purity germanium detector with a mass of 1.4 kg. The sensitivity of the vGeN experiment to neutrino magnetic moment and millicharge will be presented. The experimental constraints on these properties based on the comparison of 140.2 days reactor OFF and 69.2 days reactor ON data will be shown.
Dynamics of gravity interaction with matter at one-loop level of effective quantum field theory naturally sets the cut-off scale $\Lambda_E$ in a sub-Planckian region through incorporating the gauge coupling constant $\alpha(\Lambda_E)$ and the reduced Planckian mass $\tilde m_\textsc{pl}$ into relation $ \Lambda_E\sim \tilde m_\textsc{pl}\,\alpha(\Lambda_E)/(4\pi)$ numerically yielding $\Lambda_E\sim 10^{16}$ GeV. Such two scales are empirically inherent for an inflationary cosmology.
Dirac dark matter (DM) fermions $\chi$ can arise within the framework of Composite Higgs Models (CHMs). In such scenarios, the DM candidate is a composite neutral fermion emerging from a strongly-coupled sector. This strongly-coupled dynamics could also result in a light Higgs boson, which arises as a composite pseudo-Nambu-Goldstone boson (pNGB)—in direct analogy to pions in QCD.
We focus on an $E_6$-inspired Composite Higgs Model ($E_6$CHM), which can originate from $E_6$ supersymmetric Grand Unified Theories. In this model, the strongly-coupled sector is assumed to possess an approximate $SU(6) \subset E_6$ symmetry, which is spontaneously broken to an $SU(5)$ subgroup at a scale $f \simeq 5$–$10\,\text{TeV}$. Besides the Higgs doublet, $SU(6)$ breaking gives rise to a colored triplet $T$, which constitutes a distinctive feature of the model. The $E_6$CHM, with baryon number conservation and an additional $U(1)_E$ symmetry, can yield an $SU(5)$-singlet lightest Dirac composite particle (LDCP) $\chi$ with baryon charge $B = 1/3$ and a mass below $1\,\text{TeV}$. In this case, the LDCP is stable and can contribute to the dark matter density of the Universe.
Stringent constraints on the spin-independent dark matter-nucleon interaction limit the allowed LDCP density. For $f \sim 5\,\text{TeV}$ and an LDCP mass below $1\,\text{TeV}$, it can constitute only about $10–20\%$ of the total dark matter, while for $f \sim 10\,\text{TeV}$ the LDCP could account for the full observed DM density. We analyze the differential cross-section of LDCP-xenon nuclei scattering as a function of recoil energy, LDCP mass and magnetic moment within these constraints.
The determination of inclusive $|V_{cb}|$ from $b\to c \ell \nu$ decays relies on the Heavy Quark Expansion (HQE) involving coefficients and associated non-perturbative matrix elements, which can be expressed in terms of a number of expansion parameters. The moments of the kinematic distribution such as dilpeton mass $q^2$ or hadronic part mass $M_{X_c}$ of the decay can be computed in a similar manner and are dependent on the same HQE parameters. As a consequence measurements of $\langle q^2 \rangle$ and $\langle M_{X_c} \rangle$ is a powerful method for constraining the HQE expansion and constraining Cabibbo–Kobayashi–Maskawa matrix elements.
This analysis provides first study of inclusive semileptonic decays of $B_s$-mesons $B_s \to X_c \ell \nu$ with 121.4 $\text{fb}^{−1}$ Belle data collected at $\Upsilon(5S)$ resonance via hadronic tagging. Reconstruction of one of $B_s$-mesons allows to fix parameters of signal particle, which reconstruction is hampered due to undetected neutrino, and suppress background. The study includes modeling of signal and background events, estimation of backgrounds contribution, optimization of selection criteria and methods of kinematical parameters' resolution improvement.
T2K is a long-baseline neutrino oscillation experiment. Its primary goals are to test CP symmetry in the lepton sector and precisely measure oscillation parameters, such as $\theta_{23}$ and $\Delta m_{32}^{2}$. The experiment's near detector complex ND280 was recently upgraded and now includes a new highly-segmented scintillator detector, SuperFGD.
We present a study of the ND280 near detector's potential to search for hypothetical millicharged particles (mCPs) produced in proton-nucleus collisions at J-PARC. The analysis focuses on the signature of a pair of recoil electrons, aligned with the target, resulting from mCP double-scattering.
The latest results incorporates a more detailed simulation of the target and the entire beamline compared to previous studies, providing an refined model for the expected mCP flux. Furthermore, the analysis provides more relevant estimates of the recoil electron detection efficiencies, based on a full simulation of the detector response. Based on these results, we present updated sensitivity regions for the mCP search.
The presence of New Physics contribution to loop diagram-induced $b \to s \bar{s} s$ transitions can lead to a noticeable direct $CP$ violation in $B^+ \to K^+ K^+ K^-$ if not only the weak but also the strong phase of the New Physics are different from the Standard Model phase. We show that by using a resonance in the $K^+ K^-$ system from the tree diagram $b \to c \bar{c} s$, for example $\chi_{c0}(1P)$, we can significantly expand the possibilities of the method for NP searching in this final state. Due to the changing strong phase near the resonance pole, automatic scanning occurs over all possible values of the difference between the strong phases of the Standard Model and NP. In addition, the strongly changing resonance amplitude allows for the enhancement of the $CP$ violation effect in separate areas of the phase volume, due to the fact that the amplitudes of the SM and NP will be comparable.
The formfactors in 2d sine-Gordon (SG) model were studied using the free field representation in reflectionless points; based on the work of Lukyanov [1], we found the formfactors of the exponential operators $e^{ia\phi}$ and of their descendants $\partial^n \bar{\partial}^m e^{ia\phi}$ in the form of finite sums. We showed that the formfactors are factorized into thr product of universal transcendental part and operator-dependent rational part. We constructed a free field representation for the rational part of the formfactors. In this new representation we checked the merging of breathers, introduced screening operators to construct integrals of motion or derive equations of motion. We expect that this representation will connect the free field approach to formfactors developed by Lukyanov [1], to the other approach by Smirnov [2]
The SG model has the action
$$S[\varphi] = \int d^2x \left\{ \frac{1}{16\pi}(\partial_\mu\varphi)^2-2\mu\cos\beta\varphi \right\}$$
It is the integrable model of QFT as was shown by Zamolodchikov brothers [3]. The integrability of this model means the factorizing of any scattering into two particle scattering. It implies that one has to find the two-particle scattering matrix $S^{\sigma_1'\sigma_2'}_{\sigma_1\sigma_2} (|\theta_1-\theta_2|)$. Here $\sigma$ and $\theta$ respectively denote the topological charge and rapidity of the massive particles of the theory - kinks and antikinks. For kink $\sigma = 1$ and for antikink $\sigma = -1$. This matrix is known exactly [3] from the bootstrap approach and has the form
$$
S(\theta)=\left(\begin{array}{llll}
a(\theta) & & & \\
& b(\theta) & c(\theta) & \\
& c(\theta) & b(\theta) & \\
& & & a(\theta)
\end{array}\right)
$$
where the functions $a,b,c$ satisfy from the bootstrap
$$
b(\theta)=\frac{\operatorname{sh} \frac{\theta}{\xi}}{\operatorname{sh} \frac{i\pi-\theta}{\xi}} a(\theta), \quad
c(\theta)=\frac{\operatorname{sh} \frac{i\pi}{\xi}}{\operatorname{sh} \frac{i\pi-\theta}{\xi}} a(\theta)
$$
Here we introduced a new parameter $\xi = \frac{\beta^2}{1-\beta^2}$. The function $a(\theta)$ is obtained as the only solution by the assumptions of being meromorphic, having no poles on the physical sheet (except the imaginary axis) and satisfying $a(0) = -1$ (classical fact about kinks). This solution is then
$$
a(\theta) = \exp\left(2i\int_0^\infty \frac{dt}{t}\cdot \frac{\operatorname{sh}(\frac{\pi t}{2})\operatorname{sh}(\frac{\pi t}{2}(\xi+1))}{\operatorname{sh}(\pi t)\operatorname{sh}(\frac{\pi t}{2}\xi)} \sin(\theta t)\right)
$$
We see that this matrix is diagonal (i.e. there is no reflection) for the specific values of $\xi$, namely $\xi = \frac{1}{\nu}$, where $\nu \in \mathbb{Z}$. Those values are called reflectionless points. We study them in this work.
The formfactors are closely tied to the S-matrix. They differ from it in definition only by introducing some local operator $\mathcal{O}$. In this work we take $\mathcal{O} = e^{ia\phi}$. The formfactor is defined as
$$
F^{\mathcal{O}}_{\sigma_{2n}...\sigma_1}(\theta_{2n},...\theta_1) \equiv \langle{0}|\mathcal{O}(0)|{A_{\sigma_{2n}}(\theta_{2n})...A_{\sigma_1}(\theta_1)}\rangle_{\mathrm{in}}
$$
where $|{A_{\sigma_{2n}}(\theta_{2n})...A_{\sigma_1}(\theta_1)}\rangle$ is the multi soliton state. Knowing the formfactors allows one to calculate the correlation functions of the operator $\mathcal{O}$ which is of interest.
The S-matrix has first order poles for some values of $\theta$. In QFT a pole of S-matrix often means the presence of the bound state. For the SG model those bound states are called breathers, just like in the classical version of SG model.
Now, the governing function $a(\theta)$ in the S-matrix admits a free field representation by the bosonic field $\phi$ in such a way that $[\phi(\theta);\phi(\gamma)] = \ln a(\theta - \gamma)$. Expressing this field through oscillators as $\phi(\theta)= \int_{-\infty}^{+\infty}\frac{dt}{it}a_te^{i\theta t} $ we get the commutation relations for the generators $a_t$:
\eq$$
[a_t,a_{t'}] = t\cdot \frac{\operatorname{sh} \frac{\pi t}{2}\cdot\operatorname{sh} \frac{\pi t (\xi+1)}{2}}{\operatorname{sh} \pi t \cdot\operatorname{sh} \frac{\pi t \xi}{2}} \delta (t+t')
$$
Lukyanov's approach leads to the formula for the formfactor of exponential operator in terms of the new free bosonic field as
$$
F_{\sigma_{2n}...\sigma_1}(\theta_{2n},...\theta_1)= \mathcal{G}_a \langle\langle \mathcal{Z}_{\sigma_{2n}}(\theta_{2n})...\mathcal{Z}_{\sigma_{1}}(\theta_{1})\rangle \rangle
$$
Here $\mathcal{Z}_\pm (\theta)$ are the operators satisfying Faddeev-Zamolodchikov algebra and being expressed through field $\phi$.
We calculated the formfactors in case $\xi = \frac{1}{\nu}$ to be
$$
F_{+\ldots+-\ldots-}(\theta_{2n},...,\theta_1) =
\frac{\mathcal{G}_aC_+^{2n}}{\mathcal{N}^n}\cdot e^{\frac{a}{\beta}\sum_{k=1}^n \theta_{n+k}-\theta_k}e^{\frac{i\pi n}{2}\nu}
$$
$$
\prod_{k=1}^{n}\sum_{m_k=0}^\nu e^{-\left(\frac{2 a}{\beta}+\nu\right)\delta_{m_k}} w_{m_k} \prod_{l=1}^{n}c_-^{m_l}\prod_{j
$$
Y_+(z')Y^{(m)}_-(z)=\left(z'\over z\right)^{\nu+1\over4}h^{(m)}_{+-}\left(z\over z'\right): Y_+(z')Y^{(m)}_-(z):
$$
$$
Y^{(m')}_-(z')Y^{(m)}_-(z)=\left(z'\over z\right)^{\nu+1\over4}h^{(m'm)}_{--}\left(z\over z'\right): Y^{(m')}_-(z')Y^{(m)}_-(z):
$$
The formfactor in this representation is then
$$
F_\alpha(\theta_1,\ldots,\theta_{2N})_{\sigma_1\ldots\sigma_{2N}}
=\mathcal{G}_\alpha(\mathcal{N} C_+)^{2N}
$$
$$
\prod_{i
We studied breathers in this representation and introduced the screening currents to obtain the integrals of motion. The integral of motion of spin $s$ is
$$ I = _{31} \langle\mathbf{1}|\int du \cdot u^{s-(\nu+1)}\tilde{S}^{-1}(u)Y_+(z_{2n})...Y_+(z_{n+1})Y_-(z_n)...Y_-(z_1)\int dw \cdot w^{-\frac{2\nu+1}{\nu+1}} \cdot S(w) |\mathbf{1}\rangle_{13} $$
[1] S. L. Lukyanov, “Form factors of exponential fields in the sine-Gordon model,” Mod. Phys.
Lett. A12 (1997) 2543–2550, arXiv:hep-th/9703190.
[2] F. A. Smirnov, Form-factors in completely integrable models of quantum field theory, vol. 14.
1992.
[3] A. B. Zamolodchikov and Al. B. Zamolodchikov, “Factorized 𝑆 Matrices in Two-Dimensions
as the Exact Solutions of Certain Relativistic Quantum Field Models,” Annals Phys. 120
(1979) 253–291.
Associated multiple charmonia production in high energy proton collision has great significance for the research in QCD and the mechanism of charmonium production. In this study, data collected at CMS Run 2 in 2018 is utilized in measuring the integrated and differential cross-section and the fraction of DPS in $J/\psi-\psi(2S)$ associated production. Acceptance and efficiency corrections are applied to the selected experimental data based on MC samples. A 4-dimensional fit is carried out to exclude combinatorial and non-prompt backgrounds. The total cross-section is acquired in the fiducial volume $|y|<2.0$, $10\text{GeV/c}
This research measured, for the first time, the cross-section of $J/\psi-\psi(2S)$ associated production at $13\text{TeV}$ in central phase space, serving as a complement to the forward phase space. The results is expected to promote research in NRQCD and the mechanism of charmonium production.
The vGeN experiment located at the Kalinin Nuclear Power Plant aims to measure coherent elastic neutrino nucleus scattering (CEvNS) cross section off germanium nuclei and search for neutrino electromagnetic properties. The results of CEvNS search on part of the vGeN statistics are presented. The influence of reactor antineutrino energy spectrum and quenching-factor models uncertainties on the experiment's sensitivity to CEvNS is discussed.
Measurements of $\Delta A_{CP} = A_{CP} (D^{0} \to K^{+}K^{-})~ - ~ A_{CP} (D^{0} \to \pi^{+}\pi^{-})$ and $A_{CP} (D^{0} \to K^{0}_{S}K^{0}_{S})$ are reported. The analyses are made using pp collision data collected by the CMS experiment at the LHC in pp collisions with center-of-mass energy of 13 and 13.6 TeV. Robust trigger strategy along with novel semileptonic flavor tagging method enable a measurement precision competitive with that of the leading Heavy Flavor Physics experiments.
By solving Ward identities of matrix models one can obtain their representation as generating functions of matrix elements of two-dimensional conformal theories --- conformal matrix models. Ward identities of one-matrix model --- Virasoro constraints, are solved in terms of free boson correlators. Zamolodchikov' W-algebras appear as the main constituent of multi-matrix models Ward identities with peculiar interaction --- they are solved in terms of free higher spin fields correlators. But Ward identities of two-matrix models with naive coupling turn out to be built from something closely related, though different from W-algebras. These new algebras were discovered by A. Mironov and A. Morozov in the early 1990's and got the name \(\widetilde W\)-algebras. Corresponding conformal field theories are, again, of free higher spin fields, but with non-standard normal ordering. \(\beta\)-deformation of matrix models introduces background charge into such conformal theories, though it also have interested people per se since F. Dyson. In our work we've found Ward identities for \(\beta\)-deformed two-matrix models and described their building blocks --- \(\beta\)-deformed \(\widetilde W\) algebras.
In this work the study of the $e^+e^- → K^+K^-\pi^+\pi^-$ process in the center-of-mass energy range from 1.4 to 2 GeV is presented. The data collected with the CMD-3 detector at the VEPP-2000 collider at 82 center-of-mass energy points have been used. Their integrated luminosity has amounted to about 500 $pb^{-1}$. The $e^+e^- → K^+K^-\pi^+\pi^-$ cross section has been measured, and the results are compatible with the BaBar and the previous CMD-3 results. The intermediate states $K^*(892)^{0}K\pi$, $K^*(892)^{0}\bar{K}^*(892)^{0}$, $\rho(770)KK$, $\phi(1020)\rho(770)$, $\phi(1020)f_0(500)$ have been seen. This study results are preliminary.
In the report, the off-shell electromagnetic pion form factors in the Bethe-Salpeter formalism are considered. The separable kernel of the first rank quark-antiquark interaction is used to solve the equation analytically. The half-off-shell pion form factors $F_1$ and $F_2$, which are related to each other by the Ward-Takahashi identity, are calculated. The obtained off-shell form factors as well as static properties of the pion are compared with the results of other authors.
Short-Range Correlations (SRC) are specific type of local density fluctuations within nucleus formed by two nucleons coming as close to each other as a nucleon radius. At this moment the momenta of both paired nucleons are opposite and higher than the Fermi momentum. In JINR the second SRC experiment at BM@N took data in 2022. The hard quasi-free scattering reactions 12C(p, 2p)11B/10B/10Be were reconstructed in inverse kinematics implying a 37 GeV/c carbon beam and a liquid hydrogen target. The final state ions traveling along the beam direction pass through the magnetic spectrometer and were measured. The listed final state ions correspond to a knockout of a single proton or a pn- or pp-SRC pair from the 12C nucleus. After that the fragmentation pattern for quasi-elastic and SRC events will be studied. The analysis has been started with the improved calibration of the time-of-flight detector and reconstruction of the straight tracks upstream the magnet.
Data collected by the CMS experiment at the Large Hadron Collider have been analyzed to study the decays of the $\Omega_b^-$ baryon. More than 250 $\Omega_b^- \to \Omega^- J/\psi$ decay events were reconstructed using proton-proton collision data recorded during Run 2 (2016–2018) and Run 3 (2022–2024) at center-of-mass energies of √s = 13 TeV and √s = 13.6 TeV, with integrated luminosities of 140 fb⁻¹ and 174.2 fb⁻¹, respectively. For the first time, a signal corresponding to the new decay channel $\Omega_b^- \to \Omega^- \psi(2S)$ has been observed, and its branching ratio relative to the well-established $\Omega_b^- \to \Omega^- J/\psi$ decay has been measured.
$BB$ pairs from $\Upsilon(4S)\to BB$ decays are in $C$-odd state. However, there is a small admixture of the $C$-even state and it modifies the time dependent $CP$-asymmetry. The $C$-even component appears due to soft photon emission, breaking the pure $C$-odd nature of the initial state. Using the two-particle wave function formalism, we derive analytical expressions for $CP$-asymmetry in both pure and mixed $C$-parity states. We emphasize the strong energy dependence of the admixture magnitude.
The primary goal of the DANSS (Detector of AntiNeutrino based on Solid Scintillator) experiment is to search for neutrino oscillations into a hypothetical sterile state. Currently, the experiment provides the world's best model-independent limits for searching for sterile neutrinos in the range of $Δ𝑚^2_{14}$ ∼ 1 eV$^2$, $sin^2 2𝜃_{𝑒𝑒} < 0.01$. Achieving goals of the experiment requires high-precision energy calibration of the detector.
The talk investigates the nonlinearities of the DANSS photodetectors. The primary objective is to obtain values for the counters nonlinearity parameters, correction for which may subsequently improve the accuracy of the detector energy scale calibration. The study was conducted using data on muon events passing through the detector, accumulated over several years of experiment operation, as well as data from detailed Monte Carlo simulations of the detector. During analysis the trajectories of passing muons were reconstructed, allowing us to establish their energy release in the detector's sensitive volume. This work also examines the influence of possible detector geometric imperfections on the accuracy of muon trajectory reconstruction, proposes and implements methods for minimizing these effects.
The soloist of a period instrument orchestra and the winner of an international competition, violist Sergei Tishchenko will perform a program, which includes works by M. Reger, J. Bach, and I. von Biber.
Quasi-plane-wave beams of elementary particles are the simplest to produce and control. Therefore, calculating decay width and scattering cross-sections for particles with defined momenta remains a relevant and important task.
More complex types of beams can be constructed, such as twisted or vortex beams. In such beams the projection of the momentum onto the beam's propagation direction is well-defined and is typically the dominant component; they are monochromatic. A distinctive feature of these beams is a presence of a non-zero component of the system's orbital angular momentum projection onto the propagation direction. This leads to an azimuthal phase dependence in the plane transverse to the beam's propagation direction. Examples of such beams include Bessel and Laguerre-Gauss beams.
The width of muon weak decay has been calculated in Born approximation for different polarisation beam states of vortex muon and neutron. The analysis of the final electron energy distribution function and electron angular distribution function has been carried out.
The $\nu$GeN experiment searches for coherent elastic neutrino-nucleus scattering (CE$\nu$NS) at the Kalinin Nuclear Power Plant. To reduce background conditions, an upgrade in the form of an active anti-coincidence system based on NaI crystals is proposed. It will cover the low-threshold 1.41 kg high-purity germanium detector from all sides and suppress different backgrounds. This work presents a simulation of the main background sources (internal contamination of NaI by 40K, 238U, 232Th; surface contamination of the passive copper shield by 137Cs; 222Rn in nylon) for the new setup configuration using Geant4 with the Shielding_EMZ physics list. The simulated energy spectra for 40K, 238U, 232Th, 137Cs, and 222Rn, both with and without the application of the anti-coincidence veto, will be presented and discussed.
Photoelectron circular dichroism (PECD) [1] is a well-known phenomenon resulting in asymmetry in the angular distribution of photoelectrons produced in the ionization of randomly oriented chiral molecules in a gas by circularly polarized light relative to the direction of light propagation. Recent advances have extended this concept to vortex electrons, where the ejected photoelectron has a certain projection of its angular momentum on a given vortex axis [2].
We consider an elastic scattering of vortex electrons by chiral molecules. Using an exact theoretical framework implemented for the zero-range potential model [3] of a chiral D-glyceraldehyde molecule (C$_3$H$_6$O$_3$), we demonstrate that the angular distribution of scattered electrons depends on the handedness of both the incident electron vortex and the target molecule. This effect persists after averaging over molecular orientations and is absent in conventional plane-wave electron scattering. The predicted chiral asymmetry is quantitatively described by the coefficients $b_L^m(\theta_q)$, which determine the observable orientation-averaged angular distribution of the scattered electrons:
$$
\left
where $\theta_q$ is the vortex opening angle and $\theta_r$ is the scattering angle of the outgoing electron. Specifically, for a chiral molecule, the relation $\tilde{b}_L^m(\theta_q) = b_L^{-m}(\theta_q)$ holds, where $\tilde{b}_L^m$ denotes the coefficients for the enantiomer. This relation leads to a measurable difference in the distribution of scattered electrons for vortices with opposite orbital angular momentum projections. Our result suggests that scattering of vortex electrons could provide a new method for studying the electronic structure and properties of chiral materials.
This work was supported by the Russian Science Foundation (Grant No. 24-12-00055).
References:
[1] B. Ritchie, Theory of the angular distribution of photoelectrons ejected from optically active molecules and molecular negative ions, Phys. Rev. A 13, 1411 (1976).
[2] K. V. Bazarov and O. I. Tolstikhin, Chiral asymmetry in the photoeffect with vortex photoelectrons, Physics Letters A 556, 130818 (2025).
[3] Y. N. Demkov and V. N. Ostrovskii, Zero-Range Potentials and Their Applications in Atomic Physics (Plenum Press, New-York, 1988)
The Large Volume Detector (LVD) is located in the underground Gran Sasso Laboratory in Italy. The detector has a modular design and consists of 840 liquid-scintillation counters arranged in three towers, 280 counters per tower. Every eight counters form a “portatank” module, which is surrounded by a tracking system. This geometry, together with the underground location, enables studies of the high-energy muon component of extensive air showers (EAS), in particular muon bundles.
Muon bundles are the events in which multiple muons with parallel tracks pass through the detector simultaneously. Investigating the properties of muon bundles provides insights into the primary cosmic-ray composition and the characteristics of hadronic and nuclear interactions at high energies.
This work presents the experimental energy and spatial distributions of muons of different multiplicities: single muons, events with narrow muon pairs, and muon bundles (>5 parallel tracks). The contributions of each class of events to the total muon energy distribution were evaluated. The muon track length distribution in the scintillation counters was also studied. The corresponding energy loss distribution was reconstructed. The abovementioned characteristics do not contradict Geant4 simulations.
We present a numerical comparison between the Faddeev method—implemented via direct integration of homogeneous integral equations for the three-body T-matrix without partial-wave decomposition—and the hyperspherical harmonics (HH) method for computing binding energies of the three-nucleon systems (^3)H and (^3)He. Both approaches are applied using model nucleon–nucleon potentials. In the Faddeev method, the binding energy is determined by locating zeros of the Fredholm determinant of the discretized homogeneous system, while the HH method solves a set of coupled differential equations in the hyperradial coordinate. Our results confirm that both frameworks can reproduce experimental binding energies with comparable accuracy. Importantly, in both methods we observe similar grid-induced numerical artifacts—such as spurious roots or small shifts in binding energy—depending on the density and distribution of radial and angular grid points. These discretization effects highlight the necessity of careful convergence analysis and underscore the sensitivity of few-body calculations to numerical implementation details.
We present an implementation of the hyperspherical harmonics method for computing binding energies of three-body nuclear systems, specifically ³H and ³He. The approach is based on expanding the three-body wave function in a hyperspherical harmonics basis, which reduces the many-body Schrödinger equation to a system of coupled ordinary differential equations in the hyperradial coordinate. Using a finite-difference scheme, we solve these equations numerically for a model nucleon–nucleon potential and investigate the convergence of binding energies with respect to the number of included hypermomentum channels and the density of the radial grid. The Coulomb interaction between protons in the ³He system is incorporated via a screened potential, and its effect on the binding energy is systematically analyzed. Our results demonstrate good agreement with experimental binding energies and confirm the capability of the method to reproduce key physical features—such as the Coulomb energy shift—while remaining computationally tractable.
Supersymmetry is a promicing extention of the Standard Model. Since no superpartners have been found, it is tempting to explore the possibility that SUSY can manifest itself at low energy through a hidden sector which is responsible for the supersymmetry breaking. It is interesting that possible interactions of such a hidden sector with SM particles can be observed at relatively low energies.
In this work, we consider Minimal Supersymmetric Standard Model (MSSM) augmented with a goldstino chiral supermultiplet Φ = φ + sqrt{2}θψ + {θ}^{2} , where 𝜑 is sgoldstino field, 𝜓 is sgoldsino’s superpartner, goldstino, and 𝙵 is an auxiliary field. The vev of 𝙵, < 𝙵 >, is responsible for supersymmetry breaking. The considered values of < 𝙵 > are larger then several TeV. The sgoldstino field can be represented as 𝜑 = S + iP, where S and P are the scalar and pseudoscalar component, respectively. It is phenomenologically acceptable to have sgoldstinos as light as GeV scale. At the same time interactions of sgoldstino with the SM fields are suppressed by M/F, where M is a combination of soft supersymmetry breaking parameters.
If sgoldstinos masses are of order of several tens or hundreds MeV, the search for them is possible at the recently proposed Troitsk Meson Factory experimental facility (TiMoFey) at the Institute for Nuclear Research of Russian Academy of Sciences (Russia). It assumes use of a high intensity proton beam energy of 423 MeV and 1300 MeV at the first and second stages of operation, respectively. Collisions of protons may produce light hypothetical particles such as sgoldstinos.
Since the considered energies are sufficiently low, chiral perturbation theory (ChPT) was used. The effective interaction lagrangian for pseudoscalar sgoldstino interaction with mesons and nucleons was constructed, and cross-section of pseudoscalar sgoldstino production in proton collisions was obtained.
In this work, the model for calculating the dynamics of the energy spectrum of $\beta^-$ particles and $\bar{\nu}_e$ from nuclear fuel fission products is developed using the Monte Carlo method. The influence of the time dependence on the shape of the spectrum of fission products of $^{235}\text{U}$ and $^{239}\text{Pu}$ is investigated. The obtained spectra $\bar{\nu}_e$ of $^{235}\text{U}$ and $^{239}\text{Pu}$ are compared with similar spectra of the Huber-Müller model, and the $\beta^-$ particles spectra are compared with the spectra measured at the Kurchatov Institute (KI) and the Institut Laue-Langevin (ILL). Also there was done the research of the influence of the energy dependence of fission-inducing neutrons on the shape of the resulting spectrum of fission products
We present the results of a spectral and timing analysis of the X-ray emission from the actively accreting supermassive black hole in RX J1301.9+2747, which exhibits quasi-periodic X-ray burst-like eruptions. To investigate the features of the X-ray spectrum formation in this source during the bursts, data from ASCA, ROSAT, XMM-Newton, and NICER observations were used with a Comptonization model. We detected an increase of the photon index Γ with the mass accretion rate Ṁ, with the index saturating at Γsat = 2.7 ± 0.1 at high Ṁ values during the flare peaks. This Γ–Ṁ correlation was used to estimate the mass of the supermassive black hole in RX J1301.9+2747, M ~ 5×10^6 M⊙, using a scaling method with HLX-1 in ESO 243-49, OJ 287, and 1H 0707-495 as reference sources. We also estimated the black hole mass in RX J1301.9+2747 using an alternative method for the source's quiescent state, applying power spectral density method, in which we estimate the size of the Compton cloud (CC) as LCC$~ 5 × 10^{11} cm$. Assuming this LCC value is close to the Schwarzschild radius of the black hole, we confirmed that the mass of the supermassive black hole at the center of RX J1301.9+2747 is on the order of $2 × 10^6 M⊙$.
When calculating characteristics of various physical processes involving particle interactions, one must deal with the production and decay of unstable particles participating in these processes, such as W and Z bosons, the top quark, the Higgs boson, and others. Unlike stable particles, unstable particles are characterized not only by their mass but also by partial and total decay widths. The lifetime of an unstable particle is equal to the inverse of its total width.
To describe the contribution of an unstable particle to the amplitude of a physical process, the well-known Breit-Wigner formula is most commonly employed. The maximum of the scattering cross section, proportional to the square of the amplitude, corresponds to the resonance mass of the particle. Additionally, background processes involving the same initial and final state particles contribute to both the amplitude and the cross section of processes involving unstable particles. For example, in electron-positron annihilation into a muon pair, two Feynman diagrams contribute to the amplitude: one involving a virtual photon and another involving a Z boson. Consequently, in this case the cross section contains several terms: the background contribution (virtual photon), the signal contribution (Z boson production), and the interference between them.
The literature discusses that the Breit-Wigner formula can be refined by including the square of the particle's width in the denominator of the propagator—a refinement that may be important when achieving high experimental precision or when calculating processes involving hypothetical new particles with potentially large decay widths. The purpose of this note is to study the impact of such corrections on the integrated cross section and to compare it with the frequently used Breit-Wigner formula, in which this correction is neglected.
According to the modern physics, our Universe is baryo-asymmetric. That phenomenon can not be described in the frameworks of the Standard Model of particle physics. Globally, the Universe consists of baryon matter. However,some scenarios can lead to the existence of local antimatter domains. In the research chemical evolution of such domain is studied. The size of the domain is estimated according to the conditions of its existence. Processes of annihilation and diffusion at its border are described, taking into account ionization affect.
Coherent Elastic neutrino Nucleus Scattering (CEvNS) is the perspective technology for neutrino monitoring of nuclear reactors all over the world. Using the inorganic scintillators, as a target of detector opens the way to create simple constructions, in compare with liquid noble gases and HpGe detectors, as main target materials. In this work, were considered and modeled in Geant4 new configuration of the detector based on inorganic scintillators, and was quantified the effect of CEvNS in it. The modeled contribution of the internal radioactivity of the detector to the detector measurements is also presented.
We present a new iterative method for conversion photon energy scale calibration in the CMS experiment. The channel pi0—>gamma gamma is used for the calibration. The obtained calibration can be used in a wide variety of analyses at CMS.
The aim of this work is to determine the optimal chemical-etching exposure time required to produce an efficient reflective surface on scintillator strips. To achieve this goal, we investigated the light yield efficiency, optical transparency, and reflectivity of strips with varying reflective-layer thicknesses formed through controlled chemical etching. Light yield measurements were performed at a fixed distance between the trigger counters and the photomultiplier tube for strips exhibiting systematically varied reflective-surface thicknesses. Systems assembled from such strips are employed in high-energy physics experiments to detect charged particles. In particular, in the Mu2e and COMET experiments, events with cosmic muons registered by such systems are excluded from further data analysis.
The angular distributions of Drell-Yan lepton pairs allow to determine precisely the dynamics of vector boson production in quantum chromodynamics. The dependence of the angular coefficients $A_{i}$ on the transverse momentum of $J/\psi$ mesons was obtained at the energy of the first stage of the SPD experiment using the Pythia generator. The $J/\psi$ mesons produced in pp collisions at $\sqrt{s_{NN}} = 10$ GeV and decaying into a pair of muons were used in the analysis. The analysis is performed in the full phase space of decay muons.
Cherenkov detectors are pivotal for particle identification and velocity
measurement in high-energy physics, astrophysics, and neutrino experiments.
Their performance is critically dependent on the efficiency of the optical modules
used to detect Cherenkov photons. Modern Cherenkov detectors have an
incredible active volume like 258 kton of water in Hyper-Kamiokande. The veto
system of Hyper-Kamiokande will have an area of approximately 4800 square
meters and it leads to the need to optimise methods of photon registration. One
of these methods is the use of WLS plates, which allow increasing the light
collection area using an optimal number of 3-inch PMTs. This work presents the
development of optical modules based on a hybrid design integrating PMT and
wavelength-shifting plate. The modules are engineered to maximize photon
capture and collection efficiency and their design focuses on enhancing the
effective photosensitive area. Presented results include production and machining
of WLS plates, various testing methods for plate’s light yield, comparative
performance of WLS plates with different dopants and their concentrations,
studies of the dark rate and aging.
Black holes formed in the early Universe (primordial black holes, PBHs) may simultaneously explain several astrophysical anomalies. These include, for example, the existence of supermassive black holes in the young Universe ($z>6$, Mazzucchelli C. et al., (2017, ApJ)) and black holes with masses of $∼100\ M_\odot$ detected by gravitational-wave observatories (LVK Scientific Collaboration et al. 2025) that fall into the “forbidden” mass gap for remnants of stellar collapse Abbott R. et al. (2020b, Phys. Rev. Lett.). PBHs may also contribute a fraction of the dark matter (DM). According to P. Mroz et al. (2024, Nature), constraints derived from microlensing, astrophysical, and cosmological data suggest that compact objects in the mass ranges $~10^{-4}$`to $6\ M_\odot$ and $~10^{-5}$ to $860\ M_\odot$ can constitute no more than $1\%$ and $10\%$ of DM, respectively. However, these limits are model-dependent and typically neglect both the broad mass distribution predicted for PBHs and their possible clustering. Recent work Y. Eroshenko et al., Symmetry 15, 637 (2023) indicates that PBHs in the galactic halo may form dense clusters. If true, this clustering would significantly reduce the probability of microlensing of distant stars, effectively invalidating existing constraints. We present results of numerical simulation of dense PBH clusters evolution within the Galactic potential. The resulting PBH cluster models can be used to identify such objects through their microlensing signatures.
We derive recurrence relations for leading logarithmic all-loop quantum corrections in the case of $SO(N)$ symmetric scalar theory with arbitrary potential in a curved spacetime. On this basis, a system of renormalisation group (RG) equations in the general approach for the effective potential in the large $N$ limit and $N=1$ is obtained. As a simplest illustration, we analyse the case of power-like potentials in Jordan frame and discuss its application to the inflationary cosmology.
The interaction of primordial plasma, exemplified by scalar particles and fermions, with a closed domain wall during the radiation-dominated stage of the Universe is considered. Possible forms of the interaction Lagrangian are analyzed. Various scenarios are presented, including both conventional scattering and the “locking” effect of gas inside the wall: when the particle temperature drops below a threshold value dependent on the potential parameters, the wall becomes opaque to the particles. This effect can lead to a significant time delay in the collapse of domain walls and the formation of primordial black holes.
The optical modules will be used for the outer water Cherenkov detector of Hyper-Kamiokande. This solution increases light collection in the detector's volume. The aim of the study is to create an optical module made of a wavelength-shifting (WLS) plate (an acrylic plate with a wavelength-shifting dopant) and a photomultiplier tube (PMT) that meets the requirements for usage in water Cherenkov detectors.
Preliminary results of the characteristics of the PMT for usage as an element of a module with a WLS plate are presented, and the optimal design of the plate is developed. The choice of WLS dopants and their concentrations, as well as types of reflectors, is based on the tests performed. An assessment of the wavelength-shifting plates’ aging properties was also done.
We derive a system of generalized renormalization-group equations for the effective potential of an arbitrary scalar field theory with mass based on the Bogoliubov-Parasiuk theorem on locality of counterterms. These equations sum up the leading logarithmically divergent contributions and represent a system of nonlinear partial differential equations of the second order. We show that in some cases this system can be reduced to a system of ordinary differential equations and solved using numerical methods. In particular, for the renormalizable quartic potential, the solution can be obtained analytically recovering known well-known solutions.
We investigate the sensitivity of the Compact Linear Collider (CLIC) at √s = 3 TeV to heavy vector-like B quarks produced in pairs and decaying via B → bh and B → bZ in fully hadronic channels. A cut-based analysis is performed in both boosted Higgs and Z channels. We find that CLIC can achieve high statistical significance for VLQ-B masses in the TeV range and exclude masses up to about 1.5 TeV at 95% confidence level. Compared with current LHC and HL-LHC projections, a significant improvement in sensitivity is obtained.
The $\nu$GeN and RED-100 experimental setups deployed at Kalinin Nuclear Power Plant (KNPP) constitute sub-keV threshold detectors suitable for probing hypothetical beyond Standard Model particles known as millicharged particles ($\chi_{q}$). The setups leverage intense reactor antineutrino fluxes from a 3.1 GWth reactor with the aim to observe coherent elastic neutrino nucleus scattering (CE$\nu$NS). $\nu$GeN employs a 0.29 keV threshold point-contact Ge spectrometer situated 11m from the center of the reactor core, leveraging exceptional sensitivity to low-ionization signals. RED-100 is a 0.25 keV threshold two-phase Xe emission detector situated 19m away from the center of the reactor core, capable of detecting electron signals from low-energy interactions. Nuclear reactors are powerful sources of gamma-rays, and the proximity of these setups to a high-intensity reactor source allows for the probe of parameter space for $\chi_{q}$ mass and charge fraction ($m_{\chi_{q}},~\delta$) based on comparison of reactor ON and reactor OFF data.
The Multipurpose Detector of Muons (MDM) is being developed at the Experimental complex NEVOD (MEPhI). It is made up of 2 pairs of orthogonally oriented layers of drift chambers interleaved with 2 layers of steel absorbers. The MDM is designed to detect single and multi-particles events of cosmic ray muons up to 60º zenith angle.
The sequential model of the MDM consists of: the detector geometry and interactions with detector material modeled in Geant4; the EM fields and gas amplification within the drift chambers modeled in Garfield++; the front end electronics simulated in LTspice. The responses of this sequential model to EAS events simulated in CORSIKA are obtained and reconstructed in order to compare them with the reconstructed events of the real detector.
The poster will present the outputs of simulation at each stage of this sequence and discuss the results of reconstruction.
The goals of the νGeN experiment, carried out at the Kalinin NPP, include a measurement of coherent elastic neutrino-nucleus scattering and the search for electromagnetic properties of neutrinos, in particular its magnetic moment. The experiment relies on comparison of the spectra obtained with the reactor running and stopped to reveal the neutrino-induced signal. Thus, the components of backgrounds that can be correlated with the reactor status, such as the neutron background, are of great interest. The poster presents an analysis of the neutron background in the νGeN room, carried out using the BC-501A detector based on a liquid organic scintillator. In addition, evaluation of the thermal neutron fluxes inside the shielding of the setup is performed based on the (n, γ)-reaction peaks using a germanium spectrometer.
The results of a Monte Carlo simulation of the upgraded DANSS detector were used to construct a model of the detector signal. It was then analysed, a positron cluster was reconstructed for each IBD event. The simulation of the registration of monoenergetic neutrinos allowed to use the signal model to estimate the energy resolution of the detector.
This study investigates the stability of background conditions in the νGeN experiment at the Kalinin Nuclear Power Plant. It is demonstrated that fluctuations of the background count rate of the germanium detector inside the passive shielding are correlated with the intensity of photoabsorption peaks from radon-related gamma rays. Using data from periods with different intensity of these peaks, an energy spectrum of radon-related contribution to the experiment's region of interest is obtained.
The gauge symmetry is said unfree if the gauge transformation leaves the action functional invariant, provided that the gauge parameters are constrained by a system of partial differential equations. The most known example of this phenomenon is the volume-preserving diffeomorphism, being the gauge symmetry of unimodular gravity. Given the distinctions of the unfree gauge symmetry from the symmetry with unrestricted gauge parameters, the algebra of gauge transformations is essentially different. This affects all the key constituents of general gauge theory, including the second Noether theorem, Hamiltonian constrained formalism, BRST complex, etc. We summarize the modifications of general gauge theory worked out to cover the case of unfree gauge symmetry. The general formalism is exemplified by the higher spin models with unfree gauge symmetry.
We study hydrodynamic effects in the measurements of bulk properties of the matter produced in Au+Au collisions at $\sqrt{s_{NN}}=7.7$ GeV using identified hadrons ($\pi^{\pm}$, $K^{\pm}$ , $\bar{p}$ and $p$) with AMPT, EPOS4, SMASH and PYTHIA8 models. Midrapidity ($|y|<0.1$) results for invariant particle yield, average transverse momenta and particle ratios, in dependence of various collision centralities are presented and compared with the 2010 collected data from STAR experiment in the Beam Energy Scan (BES) Program at the Relativistic Heavy Ion Collider (RHIC).
The electromagnetic form factors (EMFFs) $G_E$ and $G_M$ of hadrons are fundamental quantities for probing the internal structure of hadrons and understanding the perturbative and nonperturbative quantum chromodynamics(QCD) effects encoded in hadrons. They contain the
information about the distribution of electric charge and magnetic moment of the hadron.
In the present work, we investigate the medium modifications of the EMFFs of the $\Sigma$ hyperons in nuclear matter using the vector meson dominance model. The in-medium effects are incorporated through density-dependent vector meson masses obtained from QCD sum rules and chiral SU(3) quark mean-field model, along with the medium modified $\Sigma$ effective mass. The sensitivity of EMFFs of $\Sigma$ with baryon density may help to probe the internal structure of baryons in extreme environments.
One of the main interests of high-energy physics is the study of the phase diagram and the localization of phase transitions from hadronic to quark–gluonic matter. There are different techniques to study the hot matter. One of them is femtoscopy, which uses two-particle correlations to extract spatiotemporal characteristics of the emission source. Another approach is based on the analysis of momentum spectra of produced particles and the extraction of thermodynamic parameters. In this work, we perform a comparative analysis of the system volume obtained using the Blast-Wave model with finite size and the cylindrical freeze-out volume calculated from femtoscopic correlation radii. We observe that the femtoscopic volume is systematically smaller than the one derived from the Blast-Wave model. In the future, these results can help to combine these two different methods and provide a more comprehensive picture of the fireball produced in heavy-ion collisions.
This study investigates the process of photon decay into an electron-positron pair in an external crossed electromagnetic field. The phenomenon is analyzed using the quasi-classical worldline instanton method.
The system of equations of motion has been solved for this field configuration.
The nature of the solutions has been analyzed depending on the relationship between the E and H fields, demonstrating the derivation of either trigonometric or hyperbolic solutions.
A formula for the effective action, S_eff, has been derived for this type of crossed field.
From the obtained equations of motion, particular cases previously described in Refs. [1] and [2] have been recovered. Furthermore, the case where the photon propagates perpendicularly to both the electric and magnetic field vectors—a configuration relevant to laser physics—has been derived.
A calculation and analysis of the electromagnetic field tensor invariants and their contractions with the photon momentum have been performed for crossed fields.
A qualitative and quantitative assessment has been provided regarding the astrophysical conditions under which the predicted effect could be observable.
Tetraquarks with two heavy flavors (charm $c$, bottom $b$) are studied within the relativistic quark model, based on the quasipotential approach and QCD. Tetraquark is treated as a diquark--antidiquark bound state. The interaction potential in the relativistic quasipotential equation contains all spin--dependent and spin--independent relativistic contributions. Finite size of the diquark is taken into account. The calculated masses of such tetraquarks are compared with the strong fall--apart decay thresholds into a pair of mesons. Results are compared with the available experimental data. The states that could be observed as narrow resonances in other decay modes are determined.
This work presents the implementation of a prototype compact reactor antineutrino detector. To detect antineutrinos via the inverse beta decay reaction, the detector combines the following components: a hydrogen-rich base, a high-atomic-number (Z) fluoride scintillator, a neutron-capturing additive, and light-collecting elements. The technology is based on several key principles: delayed coincidence technique, optical compatibility of the system, and high-Z materials enabling compact detection. More than 30 different component configurations were tested, demonstrating the system's high potential for more efficient antineutrino detection.
We perform numerical semiclassical calculations of the false vacuum decay probability for a scalar field in the Schwarzschild spacetime. The suppression $F$ of the decay probability $P \sim e^{-F}$ is given as a functional of a semiclassical solution. That solution is defined on a certain contour in complex time. We consider a model with potential $V(\phi)= m^2 \phi^2 / 2 + m \sqrt{\lambda} \phi^3 /2$. Semiclassical solutions were obtained numerically and used to calculate the decay probability around black holes of different masses. It was found that the decay probability remains exponentially suppressed in the limit of small black hole mass.
Recent data releases from the Dark Energy Spectroscopic Instrument (DESI) survey produce very strong upper constraints on the sum of neutrino masses ($\sum m_{\nu}$), putting cosmology in tension with ground-based experiments, especially in the case of inverse mass hierarchy. However, these constraints still heavily depend on the baseline CMB dataset used to calibrate DESI measurements. We explore this dependence in the case of two different data releases from the South Pole Telescope (SPT), covering the same sky field for different observational periods and analysis pipelines, producing and comparing alternative constraints on $\sum m_{\nu}$ using additional low-redshift observations.
The reconstruction of final state is studied for the process e+e-->ZH (Z->qqbar, H->bbbar) at the center of mass energy 240 GeV. The signal samples were simulated in the ILD detector model and reconstructed with particle flow technique. Several applicable jet clustering algorithms from the FastJet package have been tested. An approach based on complementarity of the recoil and direct reconstruction methods is investigated with the aim to improve Higgs mass resolution in the all-jet final states.
We evaluate the experimental sensitivity to the $CP$-odd admixture in the standard Higgs
boson for the process $e^+e^-\to HZ$. The analysis is performed assuming the future lepton collider CEPC reference
detector operating at $\sqrt{s}=240~\text{GeV}$ with statistics of $5.6~\text{ab}^{-1}$.
Using the \footnotesize WHIZARD \normalsize
generator with the Higgs Characterisation model and the \footnotesize DELPHES \normalsize detector simulation framework we obtain data samples for
different $CP$-odd Higgs admixture parameters $\tilde{c}_{ZZ}$. The initial state radiation (ISR) effects are taken into
account in \footnotesize WHIZARD \normalsize. Angular and ISR energy shift variables are used to distinguish the $CP$-odd and $CP$-even Higgs components.
The upper limit on the $CP$-odd Higgs admixture is improved by 20\% with this method compared to the standard analysis
with three angular variables.
The Multipurpose Detector of Muons (MDM) has been developed at MEPhI. The setup consists of four layers of multiwire drift chambers and two steel absorber layers with thickness of 100 mm and 200 mm each. This configuration enables registration and analysis of both single-particle and multi-particle events within a zenith-angle range of 0°– 60°.
The detector is designed to investigate the flux of muon bundles both on its own and in conjunction with other installations of the Experimental complex NEVOD. In addition, the MDM can serve as a precise test bench for studing of the spatial characteristics of charged-particle detectors.
To check the detector’s capabilities in studying muon bundles, a detailed model of the setup was developed using the Geant4 simulation toolkit. The simulations employed events generated by CORSIKA, where extensive air showers were modeled over a broad range of primary energies and zenith angles. The simulated data were processed using reconstruction methods adopted in experimental analysis. The report presents the main stages of simulation and reconstruction and discusses the obtained results.
It has been shown that the non-Abelian vortex string in 4D N=2 supersymmetric QCD (SQCD) with the U(2) gauge group and 4 flavors becomes a critical superstring. Its 10D target space is a product of the flat 4D space and an internal noncompact Calabi-Yau threefold, namely, the conifold. It was also shown that the Coulomb branch of the associated string sigma model, which opens up at strong coupling, can be described by Liouville theory. We continue the study of the recently proposed mass deformation of the U(2) theory with 4 flavors, interpolating to SQCD with the U(4) gauge group and 8 flavours of quarks, by analyzing the mass-deformed N=2 Liouville theory on the string world sheet, and show that it is always described by the trumpet geometry of the target space, which is T-dual to the 2D N=2 supersymmetric black hole. We use this correspondence to find the low-lying hadron spectrum in the deformed SQCD, and explain the expected increase in the number of hadronic states in the theory with more gauge fields and quarks by considering the near-Hagedorn behavior of the 2D black hole.
I will present an inclusive study of $B^+\!\to K^+ X_{c\bar c}$ and $B^+\!\to \bar D^{(*)0}\pi^+$ using $778~\mathrm{fb}^{-1}$ of Belle data and $362~\mathrm{fb}^{-1}$ of Belle~II data at $\sqrt{s}=10.58~\mathrm{GeV}$. The main goal is to measure the inclusive branching-fraction ratio $R_{X/J/\psi} = \mathcal{B}(B^+\!\to K^+ X(3872)) / \mathcal{B}(B^+\!\to K^+ J/\psi)$, where many systematics cancel, and to search for or constrain limit charmonium-like states such as $X(3915)$ and $X(3960)$ in the kaon recoil-mass spectrum. One $B$ meson is fully reconstructed in hadronic modes, while the signal $B$ is inferred from a single prompt kaon or pion and the known $e^+e^-$ initial state. Using the same framework, I also measure $R_{D^*/D} = \mathcal{B}(B^+\!\to\bar D^{*0}\pi^+)/\mathcal{B}(B^+\!\to\bar D^{0}\pi^+)$ and use the $B^+\!\to \bar D^{(*)0}\pi^+$ sample to provide data-driven constraints for the $B^+\!\to K^+ X_{c\bar c}$ fit.
We discuss the problem of discriminating between photon and hadron-induced extensive air showers (EAS), the difficulties of training a classifier on Monte-Carlo simulations and then applying it to the real world data. We propose to use domain adaptation techniques for aligning the feature distributions of Monte-Carlo and experimental data and thus increasing the reliability of classification.