Related papers: Constraining the pion distribution amplitude using…
I study an aspect of chiral perturbation theory (\chi PT) which enables one to ``bridge'' different reactions. That is, an operator fixed in one of the reactions can then be used to predict the other. For this purpose, I calculate the…
The measurement of the angular distribution of leptons from the decay of a $W$, $Z$, $\gamma^{\ast}$, or $\Jpsi$ produced at high transverse momentum in hadronic collisions provides a detailed test of the production and decay mechanism of…
The pion multiplicity distribution is widely believed to reflect the statistical aspects of $\bar{p}p$ annihilation at rest. We try to reproduce it in a grand canonical picture with explicit conservation of electric charge, isospin, total…
The new BABAR data on the pion-photon transition form factor arouses people's new interests on the determination of pion distribution amplitude. To explain the data, we take both the leading valence quark state's and the non-valence quark…
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 evaluate differential distributions for the four-body $p p \to n n \pi^+ \pi^+$ reaction. The amplitude for the process is calculated in the Regge approach including many diagrams. We make predictions for possible future experiments at…
Resonance production and decay into pion pairs is simulated in a non-extensive quark matter with multi-particle interactions. Final state pion spectra are found to take the form of the Tsallis distribution, in accordance with measurements.…
We study the pion electromagnetic form factor in the modulus squared dispersion relation, and do the model independent extraction of the most important nonperturbative parameters in pion light-cone distribution amplitude. The motivation of…
Kinematically complete measurements of the $pp\to pp\pi^{0}$ reaction were performed for beam energies in the range $292 - 298 $MeV. By detecting both protons in coincidence with the large acceptance COSY-TOF spectrometer set up at an…
Inclusive cross sections for pion production in proton-proton collisions are calculated for the first time based on unintegrated parton (gluon, quark, antiquark) distributions (uPDF). We use Kwieci\'nski uPDF's and phenomenological…
Two-pion correlation functions, measured as a function of azimuthal emission angle with respect to the reaction plane, provide novel information on the anisotropic shape and orientation of the pion-emitting zone formed in heavy ion…
A resonance model for two-pion production in the pion-nucleon reaction is developed that includes information obtained in the analysis of pion-nucleon scattering in a meson-exchange model. The baryonic resonances Delta(1232), N*(1440),…
The factorization theorem for $q_T$ spectra in Drell-Yan processes, boson production and semi-inclusive deep inelastic scattering allows for the determination of the non-perturbative parts of transverse momentum dependent parton…
The study of pion production in nuclei is important for signal and background determinations in current and future neutrino oscillation experiments. The first step, however, is to understand the pion production reactions at the free nucleon…
We examine the role of the elementary isoscalar pion--nucleon scattering amplitude in the description of the processes $pp \to pp\pi^0$ and $pp\to d\pi^+$ at threshold. We argue that the presently used tree level dimension two approximation…
The reaction pi N -> pi pi N is studied at tree level up to next-to-leading order in the framework of manifestly covariant baryon chiral perturbation theory with explicit Delta(1232) degrees of freedom. Using total cross section data to…
The pion structure function is investigated in a simple model, where pion and constituent quark fields are coupled through the simplest pseudoscalar coupling. The imaginary part of the forward gamma* pi-> gamma* pi scattering amplitude is…
The general context of this work is the feedback control of an infinite-dimensional system so that the closed-loop system satisfies a fading-memory property and achieves the setpoint tracking of a given reference signal. More specifically,…
Accurate modeling of how high-energy proton-proton collisions produce gamma rays through the decays of pions and other secondaries is needed to correctly interpret astrophysical observations with the Fermi-LAT telescope. In the existing…
The forward-backward asymmetry of the Drell-Yan process in dilepton decays at high invariant masses can be used to probe the parton distribution functions at large x. The behavior of three modern PDF sets (CT18NNLO, MSHT20, and NNPDF4.0)…