Pion Production Cross Sections Research Articles

Pion photoproduction in chiral perturbation theory with explicit treatment of the Δ(1232) resonance

We study the reaction of pion photoproduction on the nucleon in the framework of chiral perturbation theory with explicit $\mathrm{\ensuremath{\Delta}}(1232)$ degrees of freedom. In the covariant approach, we give results up to order ${\ensuremath{\epsilon}}^{3}$ in the small scale expansion scheme. Furthermore, we provide $\mathrm{\ensuremath{\Delta}}$-less and $\mathrm{\ensuremath{\Delta}}$-full results obtained in the heavy-baryon scheme to analyze the differences from the covariant approach. Low-energy constants are fitted to multipole amplitudes using theoretical truncation errors estimated by a Bayesian approach. We also compare our findings to data of neutral pion production cross sections and polarization asymmetries. The description of the reaction is clearly improved by the explicit treatment of the $\mathrm{\ensuremath{\Delta}}(1232)$ resonance.

Neutrino-induced single pion production and the reanalyzed bubble chamber data

In this work we report the calculation of the charged current total and differential cross sections for weak pion production with neutrinos and antineutrinos, with the final pion-nucleon pair invariant mass ${W}_{\ensuremath{\pi}N}\ensuremath{\lesssim}2\text{ }\text{ }\mathrm{GeV}$. Our results are compared with the recent reanalyzed data from the old bubble chamber experiments, that solved the discrepancy between the Argonne National Laboratory and Brookhaven National Laboratory data. We implement a model previously tested for the cuts ${W}_{\ensuremath{\pi}N}<1.4$, 1.6 GeV, which explicitly includes resonances in the first and second resonance regions within different approaches for the resonances self-energy and $\frac{3}{2}$ vertexes and propagators, a fact not usually analyzed. Our model leans on consistently effective Lagrangians that generate resonant amplitudes together with nonresonant and resonant backgrounds. Effects of hadrons' finite extension and more energetic resonances correspond to the emitted pion-nucleon invariant mass in the $1.6<{W}_{\ensuremath{\pi}N}<2\text{ }\text{ }\mathrm{GeV}$ region are taking into account using appropriate form factors in consistency with previous results on neutral current pion production calculations. Our results reproduce well the reanalyzed data without cuts and are compared with other models.

Coherent pion production in neutrino (anti-neutrino)-nucleus interaction

We present a study of coherent pion production in neutrino-nucleus interactions using the formalism based on partially conserved axial current theorem which connects the neutrino-nucleus cross section to the pion-nucleus elastic scattering cross section. Pion-nucleus elastic scattering cross section is calculated using Glauber model which takes three inputs, nuclear densities, pion-nucleon cross section and απN which is the ratio of real to imaginary part of πN forward scattering amplitude, for which the parametrizations are obtained from measured data. We calculate the differential and integrated cross sections for charge and neutral current coherent pion production in neutrino (anti-neutrino)-nucleus scattering for a range of nuclear targets from light to heavy materials such as lithium, carbon, hydrocarbon, oxygen, silicon, argon, iron and lead. The results of these cross section calculations are compared with the measured data and with the calculations from the Berger-Sehgal model and GENIE package. There is an excellent agreement between the calculated and measured cross sections with Glauber model. While GENIE and Berger-Sehgal model give a good description of the data in the lower energy range the present calculations describe the data in all energy ranges. Predictions are also made for upcoming experiments like INO and DUNE in the coherent region of neutrino cross section.

Weak pion-production and the second resonance region

In this work we report the calculation of the total cross section for pion-production by the dispersion of neutrinos on nucleons. We use a consistent formalism for the intermediate resonance states of spin-$\frac{3}{2}$, taking care on the conditions imposed by the invariance on contact transformations and using the Sachs parametrization for the form factors. In addition, we incorporate states in the second resonance region up to 1.6 GeV and implement different approaches for all the dressed resonance propagators. In addition to the $\mathrm{\ensuremath{\Delta}}(1232)$, we include the ${N}^{*}(1440)$, ${N}^{*}(1535)$, and ${N}^{*}(1520)$ resonance contributions, and it is shown that this inclusion improves the description of the total cross section regarding a model where only the $\mathrm{\ensuremath{\Delta}}(1230)$ resonance is considered. Also, results for antineutrinos are properly described.

Resonance axial-vector mass from experiments on neutrino-hydrogen and neutrino-deuterium scattering

We analyze all available experimental data on the $\nu_\mu$ and $\overline{\nu}_\mu$ total and differential cross sections of charged-current single pion production through the decay of intermediate nucleon and baryon resonances measured on hydrogen and deuterium targets in the accelerator experiments at ANL, BNL, FNAL, and CERN. These data are used to determine the current "resonance" axial-vector mass of the nucleon and to fine-tune the nonresonance non-interfering background contribution which described within the Rein-Sehgal approach. For this analysis, we revise the phenomenological model and the experimental dataset for the fits, modify the method of likelihood analysis compared to the previous study. The obtained model parameters coming in combination with a revised strategy for the normalization of the BW distributions are slightly different from the values used by default.

Update of inclusive cross sections of single and pairs of identified light charged hadrons

We report new measurements of the production cross sections of pairs of charged pions and kaons as a function of their fractional energies using various fractional-energy definitions. Two different fractional-energy definitions were used and compared to the conventional fractional-energy definition reported previously. The new variables aim at either identifying dihadron cross sections in terms of single-hadron fragmentation functions, or to provide a means of characterizing the transverse momentum created in the fragmentation process. The results were obtained applying the updated initial-state radiation correction used in other recent Belle publications on light-hadron production cross sections. In addition, production cross sections of single charged pions, kaons, and protons were also updated using this initial-state radiation correction. The cross sections are obtained from a $558\,{\rm fb}^{-1}$ data sample collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider.

Transverse momentum dependent of charged pion, kaon, and proton/antiproton fragmentation functions from e+e− annihilation process

The main aim of this paper is a new determination of transverse momentum dependence of unpolarized fragmentation function (TMD FFs) in single inclusive hadron production in electron-positron annihilation (SIA) process. Motivated by the need for a reliable and consistent determination of TMD FFs, we use the most recent TMD production cross sections of charged pions ($\pi^\pm$), kaons ($K^\pm$) and protons/antiprotons ($p/\bar{p}$) measured in inclusive $e^+e^-$ collisions by Belle Collaboration. These datasets are the first transverse momentum dependence of identified light charged hadron measurements SIA process. In this analysis, referred to as {\tt SK19 TMD FFs}, the common Gaussian distribution is used for the $P_{hT}$ dependent of the cross section. The uncertainties in the extraction of {\tt SK19 TMD FFs} are estimated using the standard "Hessian" technique. We study the quality of the TMD FFs determined in this analysis by comparing with the available recent Belle cross sections measurement. For all hadron species, we found a very good agreement between this particular set of experimental data and the corresponding theory calculations over a relatively wide range of transverse momentum $P_{hT}$. As a result of this study, suggestions are identified for possible future research considering the theory improvements and other available experimental observables.

Improved photomeson model for interactions of cosmic ray nuclei

Photohadronic interactions are important for the sources and the transport of Ultra-High Energy Cosmic Rays (UHECRs). Current state-of-the-art cosmic ray transport simulations handle nuclear disintegration at energies of the Giant Dipole Resonance at a more sophisticated level, as well as the photohadronic interactions of nucleons in the high-energy regime above the pion production threshold. However, the interactions of nuclei above the pion production threshold are commonly modeled by treating the nucleus as a superposition of free nucleons—ignoring the effect of the nuclear medium. We construct an improved, inclusive model for the photomeson regime for nuclei with A ⩽ 56 by employing more accurate, data-driven parametrizations of the interaction cross section, the fragmentation of the primary nucleus and the inclusive pion production cross section that directly affects the production of astrophysical neutrinos. We apply our results to two multi-messenger scenarios (Tidal Disruption Events and Gamma-Ray Bursts) in which photonuclear interactions in the photomeson regime are the dominant cooling process for the highest energy cosmic rays. While we find moderate changes to the mass composition of UHECRs, the astrophysical neutrino fluxes exhibit a significant (factor of a few) reduction compared to the naive superposition of free nucleons for sources of UHECR nuclei with a populated cascade. The numerical code implementing the model has been made publicly available, which facilitates the integration of our results in similar frameworks.

Simulation of Deuteron Fragmentation into Pions Produced in the Twice-Cumulative Region

Special features of the behavior of the pion-production cross section as a function of the mass number of the target nucleus are discussed for incident-deuteron fragmentation to pions produced in the twice-cumulative kinematic region. The fact that, for such pions to be produced in deuteron-nucleus collisions, the target nucleus should be heavier than the proton is the most peculiar to them. They are produced owing to the high-momentum component in both colliding nuclei. The dependence of the production cross section for twice-cumulative pions on the target mass number is simulated, and the effect of various models used to describe the structure of the target nucleus at small nucleon-nucleon distances is examined.

Transverse momentum dependent production cross sections of charged pions, kaons and protons produced in inclusive e+e− annihilation at s=10.58 GeV

We report measurements of the production cross sections of charged pions, kaons, and protons as a function of fractional energy, the event-shape variable called thrust, and the transverse momentum with respect to the thrust axis. These measurements access the transverse momenta created in the fragmentation process, which are of critical importance to the understanding of any transverse-momentum-dependent distribution and fragmentation functions. The low transverse-momentum part of the cross sections can be well described by Gaussians in transverse momentum as is generally assumed but the fractional-energy dependence is nontrivial and different hadron types have varying Gaussian widths. The width of these Gaussians decreases with thrust and shows an initially rising, then decreasing fractional-energy dependence. The widths for pions and kaons are comparable within uncertainties, while those for protons are significantly narrower. These single-hadron cross sections and Gaussian widths are obtained from a 558 fb−1 data sample collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider.8 MoreReceived 5 February 2019DOI:https://doi.org/10.1103/PhysRevD.99.112006Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasFragmentation into hadronsParticle productionQuantum chromodynamicsPhysical SystemsLepton collidersParticles & FieldsNuclear Physics

Addendum to “Muon-neutrino-induced charged-current pion production on nuclei”

This short paper is an addendum to a recent publication on charged current neutrino-induced pion production (Phys.\ Rev.\ C96 (2017) no.1, 015503). It presents comparisons of pion production cross sections measured at the T2K near detector for a CH target.

Impact of final state interactions on neutrino-nucleon pion production cross sections extracted from neutrino-deuteron reaction data

The current and near-future neutrino oscillation experiments require significantly improved neutrino-nucleus reaction models. Neutrino-nucleon pion production data play a crucial role to validate corresponding elementary amplitudes that go into such neutrino-nucleus models. Thus the currently available data extracted from charged-current neutrino-deuteron reaction data ($\nu_\mu d\to \mu^-\pi NN$) must be corrected for nuclear effects such as the Fermi motion and final state interactions (FSI). We study $\nu_\mu d\to \mu^-\pi NN$ with a theoretical model including the impulse mechanism supplemented by FSI from $NN$ and $\pi N$ rescatterings. An analysis of the spectator momentum distributions reveals that the FSI effects significantly reduce the spectra over the quasi-free peak region, and leads to a useful recipe to extract information of elementary $\nu_\mu N\to \mu^-\pi N$ processes using $\nu_\mu d\to \mu^-\pi NN$ data, with the important FSI corrections taken into account. We provide $\nu_\mu N\to \mu^-\pi N$ total cross sections by correcting the deuterium bubble chamber data for the FSI and Fermi motion. The results will bring a significant improvement on neutrino-nucleus reaction models for the near-future neutrino-oscillation experiments.

Weak pion production off the nucleon in covariant chiral perturbation theory

Weak pion production off the nucleon at low energies has been systematically investigated in manifestly relativistic baryon chiral perturbation theory with explicit inclusion of the $\Delta$(1232) resonance. Most of the involved low-energy constants have been previously determined in other processes such as pion-nucleon elastic scattering and electromagnetic pion production off the nucleon. For numerical estimates, the few remaining constants are set to be of natural size. As a result, the total cross sections for single pion production on neutrons and protons, induced either by neutrino or antineutrino, are predicted. Our results are consistent with the scarce existing experimental data except in the $\nu_\mu n\to \mu^-n\pi^+$ channel, where higher-order contributions might still be significant. The $\Delta$ resonance mechanisms lead to sizeable contributions in all channels, especially in $\nu_\mu p\to \mu^- p\pi^+$, even though the considered energies are close to the production threshold. The present study provides a well founded low-energy benchmark for phenomenological models aimed at the description of weak pion production processes in the broad kinematic range of interest for current and future neutrino-oscillation experiments.

Energetic Gamma-Ray Emission from Solar Flares

Abstract Recent advances in the γ-ray observations of solar flares by the Fermi satellite demand revisions in the hadronic γ-ray flux computation below 1 GeV. In this work, we utilize recently updated pion production cross sections, along with an accurate description of low-energy nuclear interactions. Applying these new interaction descriptions to model the Fermi Large Area Telescope solar flare data, we infer primary particle spectral parameters. Application of this new cross section description leads to significantly different spectral parameters compared to those obtained previously. Furthermore, the inclusion of nuclei in these calculations leads to a primary spectrum that is generally harder than that required from proton-only considerations. Finally, the flare data at lower MeV energies, detected by the Fermi Gamma-ray Burst Monitor, are shown to provide additional low-energy spectral information.

Deep crustal heating by neutrinos from the surface of accreting neutron stars

We present a new mechanism for deep crustal heating in accreting neutron stars. Charged pions ($\pi^+$) are produced in nuclear collisions on the neutron star surface during active accretion and upon decay they provide a flux of neutrinos into the neutron star crust. For massive and/or compact neutron stars, neutrinos deposit $\approx 1\textrm{--} 2 \, \mathrm{MeV}$ of heat per accreted nucleon into the inner crust. The strength of neutrino heating is comparable to the previously known sources of deep crustal heating, such as from pycnonuclear fusion reactions, and is relevant for studies of cooling neutron stars. We model the thermal evolution of a transient neutron star in a low-mass X-ray binary, and in the particular case of the neutron star MXB~1659-29 we show that additional deep crustal heating requires a higher thermal conductivity for the neutron star inner crust. A better knowledge of pion production cross sections near threshold would improve the accuracy of our predictions.

Event selection for the measurement of the charged current muon antineutrino single pion production cross section in the T2K near detector

Event selection for the measurement of the charged current muon antineutrino single pion production cross section in the T2K near detector

SHIELD and HZETRN comparisons of pion production cross sections

A program of comparing American (NASA) and Russian (ROSCOSMOS) space radiation transport codes has recently begun, and the first paper directly comparing the NASA and ROSCOSMOS space radiation transport codes, HZETRN and SHIELD respectively has recently appeared. The present work represents the second time that NASA and ROSCOSMOS calculations have been directly compared, and the focus here is on models of pion production cross sections used in the two transport codes mentioned above. It was found that these models are in overall moderate agreement with each other and with experimental data. Disagreements that were found are discussed.

Model-Free Parametrization of Cross Sections for Cumulative Pion Production on Nuclei in Terms of Stavinsky’s Scale Variable x

A model-free parametrization of invariant differential cross sections for cumulative pion production on nuclei ofmass number in the range of A = 2–210 in the backward hemisphere is obtained in the representation of Stavinsky’s scale variable x on the basis of cross sections available in the literature that were measured for several nuclei and several values of the angle θ at proton-beam energies in the range of E0 = 9–10 GeV. The use of this parametrization in its applicability region makes it possible to calculate pion-production cross sections in the range of x = 0.25–3.5 to an acceptable degree of precision.

Non-equilibrium dilepton production in hadronic transport approaches

In this work the non-equilibrium dilepton production from a hadronic transport approach (SMASH) is presented. The dilepton emission from the hadronic stage is of interest for current HADES results measured at GSI in the beam energy range from 1.25 - 3.5 GeV. Also at high collision energies (RHIC/LHC) the later dilute stages of the reaction are dominated by hadronic dynamics. The newly developed hadronic transport approach called SMASH (=Simulating Many Accelerated Strongly-interacting Hadrons) is introduced first. After explaining the basic interaction mechanisms, a comparison of elementary cross sections for pion production to experimental data is shown. The dilepton production within SMASH is explained in detail. The main contribution to the dilepton spectra in the low energy regime of GSI/FAIR/RHIC-BES originates from resonance decays. Results of the dilepton production with SMASH such as invariant mass spectra are shown.

First measurement of the muon neutrino charged current single pion production cross section on water with the T2K near detector

The T2K off-axis near detector, ND280, is used to make the first differential cross section measurements of muon neutrino charged current single positive pion production on a water target at energies ${\sim}0.8$ GeV. The differential measurements are presented as a function of muon and pion kinematics, in the restricted phase-space defined by $p_{\pi^+}>200$MeV/c, $p_{\mu^-}>200$MeV/c, $\cos \theta_{\pi^+}>0.3$ and $\cos \theta_{\mu^-}>0.3$. The total flux integrated $\nu_\mu$ charged current single positive pion production cross section on water in the restricted phase-space is measured to be $\langle\sigma\rangle_\phi=4.25\pm0.48 (\mathrm{stat})\pm1.56 (\mathrm{syst})\times10^{-40} \mathrm{cm}^{2}/\mathrm{nucleon}$. The total cross section is consistent with the NEUT prediction ($5.03\times10^{-40} \mathrm{cm}^{2}/\mathrm{nucleon}$) and 2$\sigma$ lower than the GENIE prediction ($7.68\times10^{-40} \mathrm{cm}^{2}/\mathrm{nucleon}$). The differential cross sections are in good agreement with the NEUT generator. The GENIE simulation reproduces well the shapes of the distributions, but over-estimates the overall cross section normalization.