Narrow Results

The purpose of this paper is to focus on the possible effective role of two relatively less-known models in analyzing comprehensively the very up-to-date data on proton–air inelastic cross-sections at high and ultra high energies. The standard versions of all the familiar simulation-based multiparticle production models, which nowadays normally claim front-ranking positions, address on the contrary, only a small part of the cross-section data for a very limited or sectional range of energy values. Against this background, the relevance and impact of the present study have finally been highlighted.

The charged current neutrino–nucleon interaction cross-section is evaluated using Thermodynamical Bag Model (TBM) in the neutrino energy range 1 < E_ν < 200 GeV with the value of the four-momentum transfer squared 0.1 < Q² < 20 GeV² and the Bjorken variable 0.1 < x < 0.5. The hadronic current carries the linear moments of the reaction that depend on the Bjorken scaling variable x as well as the four-momentum transfer. The results obtained have been compared with the experimental values.

New technique is presented for modeling total cross-section of both pp and collisions from low to ultra high energy regions using an efficient artificial neural network (ANN). We have used the input (center-of-mass energy, , and type of particle P) and output (total cross-section σ_tot) data to build a prediction model by ANN. The neural network has been trained to produce a function that studies the dependence of σ_tot on and P. The trained ANN model shows a good performance in matching the trained distributions, predicts cross-sections that are not presented in the training set. The general trend of the predicted values shows a good agreement with the recent Large Hadron Collider (LHC) measurements, where the total cross-section at and 8 TeV are measured to be 98.6 mb and 101.7 mb, respectively. The predicted values of the total cross-section at and 14 TeV are found to be 105.8 mb and 111.7 mb, respectively. Those predictions are in good agreement with Block, Cudell and Nakamura.

In this paper, one presents a naive parametrization to $pp$ and $\bar{p}p$ total cross-sections. The main goal of this parametrization is to study the possible fractal structure present in the total cross-section. The result of the fitting procedure shows two different fractal dimensions: a negative (low-energies) and a positive (high-energies). The negative fractal dimension represents the emptiness of the total cross-section structure and the positive represents the filling up process with the energy increase. Hence, the total cross-section presents a multifractal behavior. At low-energies, the odderon exchange may be associated with the negative fractal dimension and at high-energies, the pomeron may be associated with the positive fractal dimension. Therefore, the exchange of odderons and pomerons may be viewed as a transition from a less well-defined to a more well-defined internal structure, depending on the energy.

In this paper, we investigate the effect of a circularly polarized laser field on the inverse muon decay process $(e^{-}{\nu }_{\mu }\to {\nu }_e{\mu }^{-})$ in electroweak theory with the exchange of a boson vector $W^{-}$. Our method accounts for the dressing of incident electron and scattered muon by introducing the first-order laser-matter interaction of perturbation theory and using the relativistic Dirac–Volkov formalism. We have analyzed the behavior of the total cross-section (TCS) with charged-current as a function of the center-of-mass energy and the laser field parameters, such as the number of photons exchanged, the laser field strength and frequency. We have found that the circularly polarized laser field significantly affects the inverse muon decay process by reducing the TCS. We have also shown that the photonic energy transfer envelopes are perfectly symmetric with respect to the number of photons exchanged and rapidly drop when the indices of the Bessel functions are close to their arguments.

Considering the Froissart–Martin bound, Jin–Martin–Cornille bound and the optical theorem, we propose a novel parametrization for the total cross-section of proton–proton and antiproton–proton elastic scattering data. Using derivative dispersion relations we obtain the real part of the elastic scattering amplitude and thus the ρ parameter. Simultaneous fits to σtot and ρ are performed allowing very good statistical descriptions of the available data. Furthermore, predictions to σtot and ρ at energies not used in the fit procedures are presented. For σtot we obtain predictions at RHIC, LHC and future hadron collider energies.

A simple model for elastic diffractive hadron scattering, reproducing the dip-bump structure is used to analyze pp and scattering. The main emphasis is on the delicate and nontrivial dynamics in the dip-bump region, near t = -1 GeV². The simplicity of the model and the expected smallness of the absorption corrections enables one the control of various contributions to the scattering amplitude, in particular the interplay between the C-even and C-odd components of the amplitude, as well as their relative contribution, changing with s and t. The role of the nonlinearity of the Regge trajectories is scrutinized. The ratio of the real to imaginary parts of the forward amplitude, the ratio of elastic to total cross-sections and the inelastic cross-section are calculated. Predictions for the LHC energy region, where most of the existing models will be either confirmed or ruled out, are presented.

After a short introduction on the importance of the soft and of the diffractive studies in the understanding of minimum bias events, the main results obtained at LHC are discussed. This overview includes identified particle and inclusive measurements, minimum bias and underlying events, all of them shedding light on the soft process production mechanisms. The results of the inelastic cross-section measurements obtained by the LHC experiments and their compatibility are discussed together with the models used to extrapolate the data at low diffractive masses. A review of the most recent diffraction results is presented, showing the different approaches used by the LHC experiments, relying on different experimental techniques. The combination of the results obtained by ALICE, ATLAS, CMS, LHCb and TOTEM provides a wide sample of informations, covering an unprecedented pseudorapidity range. A detailed comparison between the obtained results is shown, followed by a critical discussion on the still existing discrepancies between the experimental data and the Monte Carlo used at LHC to simulate soft and diffractive physics.

Final results of a detailed analysis of p+p elastic scattering data are presented, utilizing the quark–diquark model of protons in a form proposed by Bialas and Bzdak. The differential cross-section of elastic proton–proton collisions is analyzed in a detailed and systematic manner at small momentum transfers, starting from the energy range of CERN ISR at , including also recent TOTEM data at the present LHC energies at . These studies confirm the picture that the size of proton increases systematically with increasing energies, while the size of the constituent quarks and diquarks remains approximately independent of (or only increases slightly with) the colliding energy. The detailed analysis indicates correlations between model parameters and also indicates an increasing role of shadowing at LHC energies. Within the investigated class of models, a simple and model-independent phenomenological relation was discovered that connects the total p+p scattering cross-section to the effective quark, diquark size and their average separation. Our best fits indicate that the relative error of this phenomenological relation is 10–15% in the considered energy range.

The Bialas–Bzdak model of elastic proton–proton scattering is generalized to the case when the real part of the parton–parton level forward scattering amplitude is nonvanishing. Such a generalization enables the model to describe well the dip region of the differential cross-section of elastic scattering at the intersecting storage rings (ISR) energies, and improves significantly the ability of the model to describe also the recent TOTEM data at LHC energy. Within this framework, both the increase of the total cross-section, as well as the decrease of the location of the dip with increasing colliding energies, is related to the increase of the quark–diquark distance and to the increase of the "fragility" of the protons with increasing energies. In addition, we present and test the validity of two new phenomenological relations: one of them relates the total p+p cross-section to an effective, model-independent proton radius, while the other relates the position of the dip in the differential elastic cross-section to the measured value of the total cross-section.

This paper reviews measurements of the total proton–proton cross-section at 7 TeV and 8 TeV by the ATLAS and TOTEM collaboration at the LHC. Similarities and differences between the two experiments are discussed. Some results on soft diffraction are also reviewed. The paper ends with a discussion of prospects and future plans of both experiments.

The Bialas–Bzdak model of elastic proton–proton scattering assumes a purely imaginary forward scattering amplitude, which consequently vanishes at the diffractive minima. We extended the model to arbitrarily large real parts in a way that constraints from unitarity are satisfied. The resulting model is able to describe elastic pp scattering not only at the lower ISR energies but also at in a statistically acceptable manner, both in the diffractive cone and in the region of the first diffractive minimum. The total cross-section as well as the differential cross-section of elastic proton–proton scattering is predicted for the future LHC energies of , 14, 15 TeV and also to 28 TeV. A nontrivial, significantly nonexponential feature of the differential cross-section of elastic proton–proton scattering is analyzed and the excitation function of the nonexponential behavior is predicted. The excitation function of the shadow profiles is discussed and related to saturation at small impact parameters.

In a previous work a novel parametrization was proposed for the $pp$ and $\bar{p}p$ total cross-sections. Here, results are presented for the updated analysis with taking into account the recent data from accelerator experiments as well as from cosmic ray measurements. The analytic parametrizations suggested within axiomatic quantum field theory (AQFT) provide the quantitative description of energy dependence of global scattering observables with robust values of fit parameters. Based on the fit results the estimations are derived for the total cross-section and the $\rho$ parameter in elastic $pp$ scattering at various $\sqrt{s}$ up to energy frontier $\sqrt{s}=10$ PeV which can be useful for present and future hadron colliders as well as for cosmic ray measurements at ultra-high energies.

We discuss an apparent correlation between the onset of the rising regime for the total cross-sections and the slowdown of the rise of the forward slopes with energy. It is shown that even at highest energies achieved with the large hadron collider (LHC) the proper sizes of the colliding protons comprise the bulk of the interaction region. This seems to witness that the “asymptopia” — a hypothetical “truly asymptotic” regime — lies at energies no less than ${𝒪}$ (100 TeV). In the course of reasoning, we also discuss the question of the dependence of the effective sizes of hadrons in collision on the type of their interaction.

We suggest definition of effective interaction intensity for soft hadron collisions and discuss its energy dependence in the preasymptotic region. Practical importance of this quantity consists in separation of rising interaction radius from effective interaction intensity increase both contributing to the total cross-section growth. It would be helpful for understanding the origin of this growth at the accelerator energies. The essential feature is that the effective interaction intensity is an experimentally measurable quantity.

The total cross-sections of the radiative neutron capture processes on ⁹Be, ¹⁴C, ¹⁴N, ¹⁵N and ¹⁶O are described in the framework of the modified potential cluster model with the classification of orbital states according to Young tableaux. The continued interest in the study of these reactions is due, on the one hand, to the important role played by this process in the analysis of many fundamental properties of nuclei and nuclear reactions, and, on the other hand, to the wide use of the capture cross-section data in the various applications of nuclear physics and nuclear astrophysics, and, also, to the importance of the analysis of primordial nucleosynthesis in the Universe. This article is devoted to the description of results for the processes of the radiative neutron capture on certain light atomic nuclei at thermal and astrophysical energies. The considered capture reactions are not part of stellar thermonuclear cycles, but involve in the reaction chains of inhomogeneous Big Bang models.

We have studied the neutron-capture reactions ^10,11B(n, γ) and the role of the ¹¹B(n, γ) reaction in seeding r-process nucleosynthesis. The possibility of the description of the available experimental data for cross-sections of the neutron capture reaction on ¹⁰B at thermal and astrophysical energies, taking into account the resonance at 475 keV, was considered within the framework of the modified potential cluster model (MPCM) with forbidden states (FS) and accounting for the resonance behavior of the scattering phase shifts. In the framework of the same model, the possibility of describing the available experimental data for the total cross-sections of the neutron radiative capture on ¹¹B at thermal and astrophysical energies were considered with taking into account the 21 and 430 keV resonances. Description of the available experimental data on the total cross-sections and astrophysical S-factor of the radiative proton capture on ¹¹B to the GS of ¹²C was treated at astrophysical energies. The possibility of description of the experimental data for the astrophysical S-factor of the radiative proton capture on ¹⁴C to the GS of ¹⁵N at astrophysical energies, and the radiative proton capture on ¹⁵N at the energies from 50 to 1500 keV was considered in the framework of the MPCM with the classification of the orbital states according to Young tableaux. It was shown that, on the basis of the M1 and the E1 transitions from different states of the p¹⁵N scattering to the GS of ¹⁶O in the p¹⁵N channel, it is quite succeed to explain general behavior of the S-factor in the considered energy range in the presence of two resonances.

We have studied the neutron-capture reactions ⁸Li($n,\gamma {)}^9$Li and its role in the primordial nucleosynthesis. The $n{+}^8\mathrm{\text{Li}}{\to }^9\mathrm{\text{Li}}+\gamma$ reaction has a significant astrophysical interest because it includes one of the variants of chain of primordial nucleosynthesis processes of the Universe and thermonuclear reactions in type II supernovae. Furthermore, we consider the ${}^9\mathrm{\text{Be}}{(p,\gamma )}^{10}\mathrm{\text{B}}$ reaction in the astrophysical energy range in the modified potential cluster model (MPCM) with splitting of orbital states according to Young tableaux and, in some cases, with forbidden states (FS). The reaction ${}^9\mathrm{\text{Be}}{(p,\gamma )}^{10}\mathrm{\text{B}}$ plays an important role in primordial and stellar nucleosynthesis of light elements in the $p$ shell. Hydrogen burning in second-generation stars occurs via the proton–proton (pp) chain and CNO cycle, with the ${}^9\mathrm{\text{Be}}{(p,\gamma )}^{10}\mathrm{\text{B}}$ reaction serving as an intermediate link between these cycles. Furthermore, the possibility of describing available experimental data for the total reaction cross-sections of neutron radiative capture on ${}^{10}$Be at thermal and astrophysical energies has been shown. This reaction is a part of one of the variants of the chain of primordial nucleosynthesis of the Universe due to which the elements with a mass of $A>11\text{–}12$ may be formed. The results in the field of study of thermonuclear proton-capture reaction on ${}^{10}\mathrm{\text{B}}$ at ultralow, i.e., astrophysical energies will be presented further. The possibility of description of the experimental data for the astrophysical $S$-factor of the proton radiative capture on ${}^{16}$O to the ground state (GS) of ${}^{17}$F was considered in the frame of the MPCM with FS and classification of the states according to Young tableaux. It was shown that on the basis of the $E1$ transitions from the states of $p^{16}$O scattering to the GS of ${}^{17}$F in the $p^{16}$O channel generally succeed to explain the value of measured cross-sections at astrophysical energies.