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The $\gamma\gamma\to\pi\pi$ reactions are discussed. To describe those processes, we include dipion continuum, resonances, high-energy pion-pion rescatterings, $\rho$ meson exchange and pQCD Brodsky-Lepage mechanisms. The cross section for…

High Energy Physics - Phenomenology · Physics 2017-08-23 Mariola Klusek-Gawenda , Antoni Szczurek

Experiments involving proton-proton collisions at energies $\sqrt{s_{NN}}$ = 0.9, 2.76 and 7 TeV in Large Hadron Collider (LHC) have produced a vast amount of high-precision data. Here, in this work, we have chosen to analyse the two…

High Energy Physics - Phenomenology · Physics 2014-07-11 P. Guptaroy , S. Guptaroy

We investigate the exclusive electroproduction of pi^+ mesons from nucleons. To leading twist, leading order alpha_s accuracy the corresponding production amplitude can be decomposed into pseudovector and pseudoscalar parts. Both can be…

High Energy Physics - Phenomenology · Physics 2008-11-26 L. Mankiewicz , G. Piller , A. Radyushkin

New results are reported from a measurement of $\pi^0$ electroproduction near threshold using the $p(e,e^{\prime} p)\pi^0$ reaction. The experiment was designed to determine precisely the energy dependence of $s-$ and $p-$wave…

In this work we report on the production of charged pions, kaons, and (anti) protons in pp and Pb-Pb collisions at sqrt{s_NN}= 2.76 TeV for 3 < pT < 20 GeV/c. The evolution of the nuclear modification factor, RAA, with collision centrality…

High Energy Physics - Experiment · Physics 2019-08-13 Antonio Ortiz Velasquez

The data on production of cumulative particles in the high transverse momenta domain (up to ~ 3.5 GeV/c) in proton-nucleus interactions are presented for the first time. An indication on the local character of particle production in the…

"Subthreshold pions" and so-called "hard photons" are two important channels for producing less than 1 GeV $\gamma$-rays and $e^\pm$ pairs from nuclear collisions with energy per nucleon below the $\pi$-meson production threshold. I use…

High Energy Astrophysical Phenomena · Physics 2016-12-21 Ervin Kafexhiu

The electron-positron pair production by an electron in a strong magnetic field near the process threshold is considered. The process is shown to be more probable if the spin of the initial electron is oriented along the field. In this…

High Energy Physics - Phenomenology · Physics 2011-02-21 O. P. Novak , R. I. Kholodov , P. I. Fomin

Pion production at threshold from nucleon-deuteron collisions is considered, with reference to the outgoing channel where the three-nucleon system is bound. The available experimental data are compared with calculations using accurate…

Nuclear Theory · Physics 2007-05-23 L. Canton , G. Pisent , W. Schadow , J. P. Svenne

We discuss exclusive $\phi$-meson electroproduction off the proton near threshold within the GPD factorization framework. We propose the `threshold approximation' in which only the leading term of the conformal partial wave expansion of the…

High Energy Physics - Phenomenology · Physics 2026-01-15 Yoshitaka Hatta , Henry T. Klest , Kornelija Passek-K. , Jakob Schoenleber

Data from KEK on subthreshold antiproton as well as on pi(+-) and K(+-) production in proton-nucleus reactions are described at projectile energies between 3.5 and 12.0 GeV. We use a model which considers a hadron-nucleus reaction as an…

Nuclear Theory · Physics 2008-11-26 V. I. Komarov , H. Mueller , A. Sibirtsev

We present particle spectra for charged hadrons $\pi^\pm, K^\pm, p$ and $\bar{p}$ from pp collisions at $\sqrt{s}=200$ GeV measured for the first time at forward rapidities (2.95 and 3.3). The kinematics of these measurements are skewed in…

High Energy Physics - Experiment · Physics 2008-11-26 BRAHMS Collaboration , I. Arsene

We evaluate the threshold matrix-element for the reaction $pp \to pp\pi^0$ in a fully relativistic Feynman diagrammatic approach. We employ a simple effective range approximation to take care of the S-wave $pp$ final-state interaction. The…

Nuclear Theory · Physics 2009-10-31 V. Bernard , N. Kaiser , Ulf-G. Meißner

The production of charged pion pairs via multiphoton absorption from an intense X-ray laser wave colliding with an ultrarelativistic proton beam is studied. Our calculations include the contributions from both the electromagnetic and…

High Energy Physics - Phenomenology · Physics 2011-02-15 Anis Dadi , Carsten Müller

Pion electro- and photoproduction off the nucleon close to threshold is studied in covariant baryon chiral perturbation theory at O($p^3$) in the extended-on-mass-shell scheme, with the explicit inclusion of the $\Delta(1232)$ resonance.…

High Energy Physics - Phenomenology · Physics 2021-01-04 Gustavo H. Guerrero Navarro , M. J. Vicente Vacas

The first data from MAX-lab in Lund, Sweden on pion production in photonuclear reactions at threshold energies, is presented. The decrease of the total yield of pi+ in gamma + 12C, 27Al reactions below 200 MeV as well as differential,…

We investigate photon, pion, and rho-meson production from proton synchrotron radiation in the presence of strong magnetic fields. The proton decay widths and the luminosities of the emitted particles are calculated within a relativistic…

High Energy Physics - Phenomenology · Physics 2025-12-12 Tomoyuki Maruyama , A. Baha Balantekin , Myung-Ki Cheoun , Akira Dohi , Ryo Higuch , Toshitaka Kajino , Grant J. Mathews

We assess the energy limit up to which Heavy Baryon Chiral Perturbation Theory (HBChPT) can be applied to the process of neutral pion photoproduction from the proton by analyzing the latest data collected by the MAMI/A2 collaboration at…

Nuclear Theory · Physics 2013-07-01 Cesar Fernandez-Ramirez

The positively charged pions produced in proton-proton collisions at a beam momentum of 1640 MeV/c were measured in the forward direction with a high resolution magnetic spectrograph. The missing mass distribution shows the bound state…

Nuclear Experiment · Physics 2008-11-26 GEM collaboration , M. Abdel-Bary

The single-pion production reactions $pp\to d\pi^+$, $pp\to np\pi^+$ and $pp\to pp\pi^0$ were measured at a beam momentum of 0.95 GeV/c ($T_p \approx$ 400 MeV) using the short version of the COSY-TOF spectrometer. The central calorimeter…