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In this paper, we investigate the effect of repulsive interaction between hadrons on the susceptibilities of conserved charges, namely baryon number (B), electric charge (Q) and strangeness (S). We estimate second-, fourth- and sixth-order susceptibilities of conserved charges, their differences, ratios and correlations within ambit of mean-field hadron resonance gas (MFHRG) model. We consider repulsive mean-field interaction among meson pairs, baryon pairs and antibaryon pairs separately and constrain them by confronting the results of various susceptibilities with the recent lattice quantum chromodynamics (LQCD) data. We find that the repulsive interactions between baryon–baryon pairs and antibaryon–antibaryon pairs are sufficient to describe the baryon susceptibilities of hadronic matter at temperatures below QCD transition temperature. However, small but finite mesonic repulsive interaction is needed to describe electric charge and strangeness susceptibilities. We finally conclude that the repulsive interaction between hadrons play a very important role in describing the thermodynamic properties of hadronic matter, especially near the quark–hadron phase transition temperature (Tc). The mean-field parameter for baryons (KB) should be constrained in the range 0.40≤KB≤0.450GeVfm3 to get a good agreement of baryon susceptibilities with the LQCD results, whereas meson mean-field parameter KM∼0.05GeVfm3 must be included with KB to get a reasonable agreement of MFHRG model with the LQCD results for electric charge and strangeness susceptibilities. [ABSTRACT FROM AUTHOR]

Properties of the underlying-event in pp interactions are investigated primarily via the strange hadrons K S 0 , Λ and Λ ¯ , as reconstructed using the ATLAS detector at the LHC in minimum-bias pp collision data at s = 13 TeV. The hadrons are reconstructed via the identification of the displaced two-particle vertices corresponding to the decay modes , Λ → π - p and Λ ¯ → π + p ¯ . These are used in the construction of underlying-event observables in azimuthal regions computed relative to the leading charged-particle jet in the event. None of the hadronisation and underlying-event physics models considered can describe the data over the full kinematic range considered. Events with a leading charged-particle jet in the range of 10 < p T ≤ 40 GeV are studied using the number of prompt charged particles in the transverse region. The ratio N (Λ + Λ ¯) / N (K S 0) as a function of the number of such charged particles varies only slightly over this range. This disagrees with the expectations of some of the considered Monte Carlo models. [ABSTRACT FROM AUTHOR]

Numerical simulations of three and four top quark hadroproduction processes are carried out in the SMEFT model framework. The simulated data are used to derive expected theoretical constraints on Wilson coefficients of relevant SMEFT operators of dimension six. Obtained limits for both cases are discussed and compared in terms of processes' sensitivity to possible BSM contribution. Results show that operator O t t 1 is better constrained by the process of four top quark production, whereas other four operators O Q Q 1 , O Q t 1 , O Q t 8 and O Q Q 8 , are similarly constrained in three and four top quark production processes. In all cases, the expected limits taken from the simultaneous analysis of the production of three and four top quarks are strengthened. Analytical expressions for the partial amplitudes of the processes t t → t t and t t ̄ → t t ̄ caused by the operators O t t 1 , O Q Q 1 , O Q t 1 , O Q t 8 , O Q Q 8 were obtained for the first time. Based on the expressions of the obtained partial amplitudes, graphs of the perturbative unitarity boundary for the listed operators were drawn. The question of how kinematic cuts motivated by partial unitarity affect the resulting constraints on the Willson coefficients is addressed. It is shown that in all cases the limits are getting somewhat worse if such cuts are applied. [ABSTRACT FROM AUTHOR]

In this article we present an overview of the SMASH hadronic transport approach that is applied for non-equilibrium dynamics of hadrons in heavy-ion collisions. We will give an overview about the ingredients of the approach and the applications for the dynamical description of heavy-ion collisions and for calculations of fundamental properties of the hadron gas. The main emphasis of the article will be the infrastructure for sustainable software development that we have developed over the last 10 years including extensive unit tests and continuous integration. We will also provide one section about the performance of the code and how it can be analyzed and improved in the future. [ABSTRACT FROM AUTHOR]

The paper presents the results of long-term, continuous observations of the Cherenkov light at the Yakutsk array. The Cherenkov light measurements allow one to reconstruct the longitudinal development of the shower, which is associated with both the model of hadron interactions and the mass composition of cosmic rays. The paper also provides a review of the results that are important for the physics of air showers and the astrophysics of cosmic rays, obtained over a long period of time at the Yakutsk array. [ABSTRACT FROM AUTHOR]

In this paper, we estimate the number of event topologies that have the potential to be produced in p p collisions at the Large Hadron Collider (LHC) without violating kinematic and other constraints. We use numerical calculations and combinatorics, guided by large-scale Monte Carlo simulations of Standard Model (SM) processes. Then, we set the upper limit on the probability that new physics may escape detection, assuming a model-agnostic approach. The calculated probability is unexpectedly large, and the fact that LHC has not found new physics until now is not entirely surprising. Theoretical limitations and experimental challenges in observing new physics within the studied exclusive event classes are examined. [ABSTRACT FROM AUTHOR]

In this paper, we present our approach to the treatment of final-state interaction of hadrons. It is based on the assumption that quark–antiquark pairs are produced at small distances, while the interaction of hadrons takes place at larger distances. As a result, the effects of final-state interaction are determined by the wave function of produced hadronic system. The account for final-state interaction within this approach allows us to successfully describe the energy dependence of cross-sections of many processes, as well as electromagnetic form factors of hadrons. [ABSTRACT FROM AUTHOR]

With the explosion of data on jet-based observables in relativistic heavy-ion collisions at the Large Hadron Collider and the Relativistic Heavy-Ion Collider, perturbative Quantum Chromodynamics (pQCD)-based simulations of these processes, often interacting with an expanding viscous fluid dynamical background, have taken center stage. This review is meant to bridge the gap between theory, simulation and phenomenology of jet modification in a dense medium. We will demonstrate how the existence of such end-to-end event generators with semi-realistic or even fully realistic final states allows for the most rigorous comparisons between pQCD-based jet modification theory and experiment. State-of-the-art calculations of several jet-based observables are presented. Extensions of this theory to jets in the small systems of p–A and e–A collisions are discussed. [ABSTRACT FROM AUTHOR]

The status of -scaling theory is briefly reviewed. Basic physical principles of self-similarity, locality, and fractality are discussed. The microscopic scenario of interactions of hadrons and nuclei at a constituent level in terms of dimensionless variables is studied. Applicability of the -scaling approach for the description of polarization processes is justified. A conservation law for new quantity—fractal cumulativity—is formulated. The statistical properties and crossing symmetry of fractal dimensions are investigated. [ABSTRACT FROM AUTHOR]

Interest in studying multiparticle-production processes in lepton and hadron interactions has not faded to date. The development of strong-interaction theory in the form of quantum chromodynamics (QCD) permits describing these interactions at the level of quarks and gluons. The transition from partons to observed hadrons at the hadronization stage is very difficult. The gluon-dominance model describing multiparticle production of secondaries and including the hadronization stage is proposed in the present study. This model is applied to describing electron–positron annihilation. It confirms an active role of the gluon component in the formation of secondaries, is indicative of the fragmentation mechanism of hadronization occurring in a vacuum, and describes experimental data on multiplicity distributions. [ABSTRACT FROM AUTHOR]

We provide an update on our semi-classical transport approach for quarkonium production in high-energy heavy-ion collisions, focusing on J / ψ and ψ (2 S) mesons in 5.02 TeV Pb-Pb collisions at the Large Hadron Collider (LHC) at both forward and mid-rapidity. In particular, we employ the most recent charm-production cross sections reported in pp collisions, which are pivotal for the magnitude of the regeneration contribution, and their modifications due to cold-nuclear-matter (CNM) effects. Multi-differential observables are calculated in terms of nuclear modification factors as a function of centrality, transverse momentum, and rapidity, including the contributions from feeddown from bottom hadron decays. For our predictions for ψ (2 S) production, the mechanism of sequential regeneration relative to the more strongly bound J / ψ meson plays an important role in interpreting recent ALICE data. [ABSTRACT FROM AUTHOR]

We update the phenomenological parameters of the Transverse Momentum Dependent (TMD, or unintegrated) gluon density in a proton proposed in our previous studies. This analysis is based on the analytical expression for starting gluon distribution which provides a self-consistent simultaneous description of HERA data on proton structure function , reduced cross section for the electron-proton deep inelastic scattering at low and soft hadron production in collisions at the LHC conditions. We extend it to the whole kinematical region using the Catani–Ciafaloni–Fiorani–Marchesini (CCFM) evolution equation. Exploiting our previous results on a number of semihard QCD processes, we performed a combined fit to an extended set of LHC and HERA data, comprising a total of 509 points from 16 data sets. We illustrate our fit by applying the derived TMD gluon density in a proton to inclusive prompt photon photoproduction at HERA. [ABSTRACT FROM AUTHOR]

In models with large extra dimensions, "miniature" black holes (BHs) might be produced in high-energy proton–proton collisions at the Large Hadron Collider (LHC). In the semi-classical regime, those BHs thermally decay, giving rise to large-multiplicity final states with jets and leptons. On the other hand, similar final states are also expected in the production of electroweak sphaleron/instanton-induced processes. We investigate whether one can discriminate these scenarios when BH or sphaleron-like events are observed in the LHC using machine learning (ML) methods. Classification among several BH scenarios with different numbers of extra dimensions and the minimal BH masses is also examined. In this study we consider three ML models: XGBoost algorithms with (1) high- and (2) low-level inputs, and (3) a Residual Convolutional Neural Network. In the latter case, the low-level detector information is converted into an input format of three-layer binned event images, where the value of each bin corresponds to the energy deposited in various detector subsystems. We demonstrate that only a small number of detected events are sufficient to effectively discriminate between the sphaleron and BH processes. Separation between BH scenarios with different minimal masses is possible with an order of 10 events passing the preselection. A sufficient number of events could be observed in combined Run-2 and -3 data, if the production cross section is not much smaller than the present limit ∼ 0.1 fb. We find, however, that a large number of events is needed to discriminate between BH hypotheses with the same minimal BH mass, but different numbers of extra dimensions. [ABSTRACT FROM AUTHOR]

The charged-particle transverse momentum spectra ( p T -spectra) measured by the ALICE collaboration for pp collisions at s = 7 and 13 TeV have been studied using a thermodynamically consistent form of Tsallis non-extensive statistics. The Tsallis distribution function is fitted to the p T -spectra and the results are analyzed as a function of final state charged-particle multiplicity for various light flavor and strange particles, such as π ± , K ± , p + p ¯ , ϕ , Λ + Λ ¯ , Ξ + Ξ ¯ , Ω + Ω ¯ . At the LHC energies, particles and antiparticles are produced in equal numbers. However, the equality of particle and antiparticle yields at the kinetic freeze-out may imply that they have the same but opposite chemical potential which is not necessarily zero. We use an alternative procedure that makes use of parameter redundancy, by introducing a finite chemical potential at the kinetic freeze-out stage. This article emphasizes the importance of the chemical potential of the system produced in pp collisions at the LHC energies using the Tsallis distribution function which brings the system to a single freeze-out scenario. [ABSTRACT FROM AUTHOR]

The notion of cumulative activity for elastic events in hadron collision is introduced. The interrelation between centrality and cumulative activities of the elastic and inelastic events has been established for hadron scattering. Considerations on its application are presented. [ABSTRACT FROM AUTHOR]

A study of double‐charmed meson production in high‐energy proton–proton collisions at the Large Hadron Collider is presented. Considering the color dipole formalism developed in the transverse momentum representation along with the double parton scattering mechanism, predictions are made for the transverse momentum differential cross section for different pairs of D$$ D $$‐mesons. The theoretical results cover the center‐of‐mass energy and forward rapidities available by the LHCb experiment. The proton–proton results considering different unintegrated gluon distributions are compared to the respective data collected at the LHC. [ABSTRACT FROM AUTHOR]

We made the first attempt to understand the observed unusual t dependence of single-spin asymmetry observed in the HJET experiment at RHIC. Usually, the interaction of hadrons is presented as a long-range Coulomb interaction and a short-range strong interaction with Coulomb corrections. Such a division gives rise to a Coulomb phase of the hadronic term. Conversely, here we consider short-range hadronic interaction as a correction to the long-range electromagnetic term, i.e., we treat it as an absorptive correction. This significantly affects the Coulomb-nuclear interference, which is a source of single-spin azimuthal asymmetry at small angles. [ABSTRACT FROM AUTHOR]

Here we consider the results of direct measurements of muons in extensive air showers with zenith angles and energy above eV, obtained at the Pierre Auger Observatory and Yakutsk array. In both experiments muons were registered with underground scintillation detectors with GeV energy threshold. Measured density values were compared to theoretical predictions calculated within the framework of the qgsjet-ii.04 hadron interaction model. They differ by factor (stat). We demonstrate that this difference is due to overestimation of muon densities by 1.22 times and underestimation of primary energy by 1.25 times in the Auger experiment. [ABSTRACT FROM AUTHOR]

The Compact Muon Solenoid (CMS) experiment is a general-purpose detector for high-energy collision at the Large Hadron Collider (LHC) at CERN. It employs an online data quality monitoring (DQM) system to promptly spot and diagnose particle data acquisition problems to avoid data quality loss. In this study, we present a semi-supervised spatio-temporal anomaly detection (AD) monitoring system for the physics particle reading channels of the Hadron Calorimeter (HCAL) of the CMS using three-dimensional digi-occupancy map data of the DQM. We propose the GraphSTAD system, which employs convolutional and graph neural networks to learn local spatial characteristics induced by particles traversing the detector and the global behavior owing to shared backend circuit connections and housing boxes of the channels, respectively. Recurrent neural networks capture the temporal evolution of the extracted spatial features. We validate the accuracy of the proposed AD system in capturing diverse channel fault types using the LHC collision data sets. The GraphSTAD system achieves production-level accuracy and is being integrated into the CMS core production system for real-time monitoring of the HCAL. We provide a quantitative performance comparison with alternative benchmark models to demonstrate the promising leverage of the presented system. [ABSTRACT FROM AUTHOR]

The interactions of kaons (K) and antikaons ( K ¯ ) with few nucleons (N) were studied so far using kaonic atom data and measurements of kaon production and interaction yields in nuclei. Some details of the three-body KNN and K ¯ NN dynamics are still not well understood, mainly due to the overlap with multi-nucleon interactions in nuclei. An alternative method to probe the dynamics of three-body systems with kaons is to study the final state interaction within triplet of particles emitted in pp collisions at the Large Hadron Collider, which are free from effects due to the presence of bound nucleons. This Letter reports the first femtoscopic study of p–p–K + and p–p–K - correlations measured in high-multiplicity pp collisions at s = 13 TeV by the ALICE Collaboration. The analysis shows that the measured p–p–K + and p–p–K - correlation functions can be interpreted in terms of pairwise interactions in the triplets, indicating that the dynamics of such systems is dominated by the two-body interactions without significant contributions from three-body effects or bound states. [ABSTRACT FROM AUTHOR]

The coplanarity of subcores in -ray–hadron families of the so-called long-range near-side "ridge" effect discovered by the CMS Collaboration at the LHC can be described in terms of the FANSY 2.0 model, which reproduces the coplanar generation of the most energetic particles in hadron interactions at superhigh energies. Coplanar generation can be explained, in particular, by the hypothesis of change of the signature of the metric of the space–time continuum, namely, a fluctuation transformation of the basic three-dimensional state into two-dimensional one (3D 2D). A method is proposed for experimental verification of this hypothesis by studying the azimuthal correlations of different particles in hadron interactions. [ABSTRACT FROM AUTHOR]

Strange hadron transverse momentum spectra are analyzed in symmetric p p and P b P b and asymmetric p P b collision systems for their dependence on rapidity and event charged-particle multiplicity. The thermodynamically consistent Tsallis models with and without flow velocity are used to reproduce the experimental data, extracting the freeze-out parameters to gain insights into the underlying physics of the collision processes by looking into the parameters change with different multiplicities, particle types, and collision geometries. We found that with an increase in the event multiplicity, the average transverse flow velocity, effective, and kinetic freezeout temperatures increase, with heavier strange particle species exhibiting a more significant increase. The value of the non-extensivity parameter decreases with an increase in the multiplicity of the particles. For heavier particles, larger T e f f and T 0 and smaller q have been observed, confirming the quick thermalization and equilibrium for massive particles. Furthermore, the differences in parameter values for particle species are more significant in p p and p P b collisions than in P b P b collisions. In addition, in symmetric p p and P b P b collisions, parameter values ( q , T 0 , β T ) show more significant shifts for heavier particles compared to the lighter ones. In contrast, in asymmetric p P b collisions, both heavier and lighter particles display uniform linear progression. [ABSTRACT FROM AUTHOR]

The general-purpose Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC) at CERN incorporates a hadronic calorimeter to register the energies of the charged and neutral hadrons produced in proton–proton collisions at the LHC at a center-of-mass energy of 13.6 TeV. This calorimeter is located inside a superconducting solenoid that is 6 m in diameter and 12.5 m in length, generating a central magnetic flux density of 3.8 T. For operating optimally in the high pileup and high radiation environment of the High-Luminosity LHC, the existing CMS endcap calorimeters will be replaced with a new high granularity calorimeter (HGCal) with an electromagnetic section and a hadronic section in each of the two endcaps. The hadronic section of the HGCal will include 44 stainless-steel absorber plates with a relative permeability value well below 1.05. The volume occupied by 22 plates in each endcap is about 21 m3. The calculation of the axial electromagnetic forces acting on the absorber plates is a crucial element in designing the mechanical construction of the device. With a three-dimensional computer model of the CMS magnet, the axial forces on each absorber plate were calculated, and the dependence of forces on the central magnetic flux density value is presented. The method of calculation and the obtained results are discussed. [ABSTRACT FROM AUTHOR]

We introduce the notion of cumulative activity for inelastic events generated under hadron collisions, and discuss its energy dependence and connection with the reflective scattering mode. These issues are relevant for enlightening the asymptotic dynamics in view of the LHC measurements. [ABSTRACT FROM AUTHOR]

The high-energy atmospheric neutrino flux is dominated by neutrinos from the decays of charmed hadrons produced in the forward direction by cosmic ray interactions with air nuclei. We evaluate the charm contributions to the prompt atmospheric neutrino flux as a function of the center-of-mass energy s of the hadronic collision and of the center-of-mass rapidity y of the produced charm hadron. Uncertainties associated with parton distribution functions are also evaluated as a function of y. We find that the y coverage of LHCb for forward heavy-flavour production, complemented by the angular coverage of present and future forward neutrino experiments at the LHC, bracket the most interesting y regions for the prompt atmospheric neutrino flux. At s = 14 TeV foreseen for the HL-LHC phase, nucleon collisions in air contribute to the prompt neutrino flux prominently below Eν ~ 107 GeV. Measurements of forward charm and/or forward neutrinos produced in hadron collisions up to s = 100 TeV, which might become possible at the FCC, are relevant for the prompt atmospheric neutrino flux up to Eν = 108 GeV and beyond. [ABSTRACT FROM AUTHOR]

We estimate one-loop electroweak radiation corrections to the process of dilepton production in the photon fusion channel during hadron collisions for the Large Hadron Collider (LHC) experimental program of the study of the Drell–Yan process. We numerically and comprehensively analyze the effects of electroweak corrections to cross sections and the forward–backward asymmetry in a wide kinematic region, including for the CMS LHC experiment in the Run3/HL mode, which corresponds to superhigh energies and invariant masses of the lepton pair. [ABSTRACT FROM AUTHOR]

The analysis of the spatiotemporal picture of particle radiation in relativistic heavy-ion collisions in terms of correlation femtoscopy scales, emission, and source functions allows one to probe the character of the evolution of the system created in the collision. Realistic models, such as the integrated hydrokinetic model (iHKM), used in the present work, are able to simulate the entire evolution process of strongly interacting matter produced in high-energy nuclear collisions. The mentioned model describes all the stages of the system's evolution, including thermalisation and hydrodynamisation, which can help researchers figure out the specific details of the process and better understand the formation mechanisms of certain observables. In the current paper, we investigated the behaviour of the pion and kaon interferometry radii and their connection with emission functions in ultrarelativistic heavy-ion collisions at the Large Hadron Collider within iHKM. We focused on the study of the emission time scales at different energies for both particle species (pions and kaons) aiming to gain deeper insight into relation of these scales and the peculiarities of the mentioned system's collective expansion and decay with the experimentally observed femtoscopy radii. One of our main interests was the problem of the total system's lifetime estimation based on the femtoscopy analysis. [ABSTRACT FROM AUTHOR]

The ALICE experiment at the LHC is designed to explore the hot and dense medium produced in heavy-ion collisions, the so-called quark–gluon plasma (QGP). Antineutron production is a poorly explored domain of high energy physics, although it is interesting in the context of hadrons decaying into antineutrons, the interaction of antineutrons with hadrons, and searching for bound states of antineutrons. We present a method for measuring antineutrons by the electromagnetic calorimeter PHOS of the ALICE experiment. An antineutron can be identified by the cluster shape and the energy deposition in the calorimeter, and its momentum can be reconstructed using the time-of-flight information. The proposed method was verified via the reconstruction of through decays and with an antineutron identified in the PHOS. [ABSTRACT FROM AUTHOR]

We present a computational investigation of a problem of hadron collisions from recent years, that of baryon anticorrelations. This is an experimental dearth of baryons near other baryons in phase space, not seen upon examining numerical Monte Carlo simulations. We have addressed one of the best known Monte Carlo codes, PYTHIA, to see what baryon (anti)correlations it produces, where they are originated at the string-fragmentation level in the underlying Lund model, and what simple modifications could lead to better agreement with data. We propose two ad-hoc alterations of the fragmentation code, a "one-baryon" and an "always-baryon" policies that qualitatively reproduce the data behaviour, i.e anticorrelation, and suggest that lacking Pauli-principle induced corrections at the quark level could be the culprit behind the current disagreement between computations and experiment. [ABSTRACT FROM AUTHOR]

This communication is a follow-up on our previous study [Few Body Syst. 61, 49 (2020)] suggesting the use of femtoscopic measurements of J / ψ -proton correlation functions in high-energy hadron collisions to access information on the origin of the proton's mass. The QCD multipole expansion allows us to express the J / ψ -proton scattering amplitude in terms of the product of the J / ψ chromopolarizability and a scalar gluon gravitational (GFF) form factor. The scalar gluon GFF gives the gluonic contribution to the nucleon mass and determines the corresponding matter radius. We show that J / ψ -proton femtoscopic correlation function displays clear sensitivity to the scalar gluon GFF for a wide range of the J / ψ chromopolarizability. [ABSTRACT FROM AUTHOR]

We apply an equal-velocity quark combination model to study the Λ c + / D 0 ratio in the range p T ≲ 10 GeV/c in pp collisions at s = 13 TeV. We decompose the ratio into four parts which are related to quark numbers, light-flavor quark p T spectrum, charm quark p T spectrum, momentum correlation between light and charm quarks, respectively. Their influence on Λ c + / D 0 ratio is individually studied. The curvature property of light-flavor quark p T spectrum is the main reason of the non-monotonic p T dependence of Λ c + / D 0 ratio exhibited in high multiplicity events. Moreover, the multiplicity dependence of Λ c + / D 0 ratio as the function of p T is mainly because of the multiplicity dependence of light-flavor quark p T spectrum. Using the light-flavor quark p T spectrum obtained from experimental data of light-flavor hadrons and charm quark p T spectrum obtained from FONLL and/or PYTHIA calculations, the p T dependence of experimental data of Λ c + / D 0 ratio in high multiplicity events and that in low multiplicity events in pp collisions at s = 13 TeV are reasonably understood. [ABSTRACT FROM AUTHOR]