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Measurements of the polarization of the final proton in elastic e-p scattering drastically changed our knowledge about the electromagnetic form factors of the proton. Here we present our results of the calculation of the polarization of the…

High Energy Physics - Phenomenology · Physics 2013-08-15 Samoil M. Bilenky , Ekaterina Christova

Using a symmetry-preserving truncation of the quantum field equations describing hadron properties, parameter-free predictions are delivered for pion and kaon elastic electromagnetic form factors, $F_{P=\pi,K}$, thereby unifying them with…

High Energy Physics - Phenomenology · Physics 2024-06-21 Zhao-Qian Yao , Daniele Binosi , Craig D. Roberts

The study delves into the production of (multi-)strange hadrons in proton-proton collisions at LHC. Novel observables are proposed to distinguish between EPOS4, based on core-corona separation between a thermalised QGP phase and a vacuum…

High Energy Physics - Phenomenology · Physics 2024-10-07 Christian Bierlich , Stefano Cannito , Valentina Zaccolo

Using the helicity amplitudes formalism, we study deeply virtual exclusive electron photo-production off an unpolarized nucleon target, $ep \rightarrow e' p' \gamma$, through a range of kinematics both in the fixed target setting with…

High Energy Physics - Phenomenology · Physics 2021-11-23 Brandon Kriesten , Simonetta Liuti

Using a relativistic effective Lagrangian at the hadronic level, near-threshold $\omega$ and $\phi$ meson productions in proton proton ($pp$) collisions, $p p \to p p \omega/\phi$, are studied within the distorted wave Born approximation.…

Nuclear Theory · Physics 2009-11-10 K. Tsushima , K. Nakayama

Recently, there has been considerable theoretical interest in determining strange quark contributions to hadronic matrix elements. Such matrix elements can be accessed through the nucleon's neutral weak form factors as determined in parity…

Nuclear Experiment · Physics 2019-08-14 E. J. Beise

The dependence of the differential cross section and polarization observables in the $\bar N+N\to \pi +e^++e^-$ reaction on the polarizations of the proton target and antiproton beam (the produced electron may be unpolarized or…

Nuclear Theory · Physics 2015-06-05 G. I. Gakh , E. Tomasi-Gustafsson , A. Dbeyssi , A. G. Gakh

Dalitz decays of $\omega$ and $\rho$ mesons, $\omega\to \pi^0\gamma^*\to\pi^0 e^+e^-$ and $\rho^0\to \pi^0\gamma^*\to\pi^0 e^+e^-$, produced in $pp$ collisions are calculated within a covariant effective meson-nucleon theory. We argue that…

Nuclear Theory · Physics 2008-11-26 L. P. Kaptari , B. Kampfer

We report on a measurement of the parity-violating asymmetry in the scattering of longitudinally polarized electrons on unpolarized protons at a $Q^2$ of 0.230 (GeV/c)^2 and a scattering angle of \theta_e = 30^o - 40^o. Using a large…

We argue that high-quality data on the reaction $e^+e^-\to \pi^+\pi^-\eta$ will allow one to determine the doubly-virtual form factor $\eta\to \gamma^*\gamma^*$ in a model-independent way with controlled accuracy. This is an important step…

High Energy Physics - Phenomenology · Physics 2021-11-17 S. Holz , J. Plenter , C. W. Xiao , T. Dato , C. Hanhart , B. Kubis , U. -G. Meißner , A. Wirzba

We analyse the isoscalar vector current form factors of the nucleon using dispersion relations. In addition to the usual vector meson poles, we account for the K\bar{K}-continuum contribution by drawing upon a recent analytic continuation…

High Energy Physics - Phenomenology · Physics 2014-11-17 H. -W. Hammer , M. J. Ramsey-Musolf

Using the CLEO~II detector, we have measured the differential cross sections for exclusive two-photon production of light pseudoscalar mesons $\pi^0$, $\eta$, and $\eta^{\prime}$. From our measurements we have obtained the form factors…

High Energy Physics - Experiment · Physics 2010-04-08 CLEO Collaboration , J. Gronberg et al

We estimate two-photon exchange contribution to the process $e^+ +e^- \to p + \bar{p}$. The two-photon exchange corrections to double spin polarization observables and form factors in the time-like region are calculated. The corrections are…

Nuclear Theory · Physics 2008-11-26 D. Y. Chen , H. Q. Zhou , Y. B. Dong

The production of pseudo scalar, Eeta, Eta-prime, and vector, Omega, Rho, Phi, mesons in NN collisions at threshold-near energies is analyzed within a covariant effective meson-nucleon theory. It is shown that a good description of cross…

High Energy Physics - Phenomenology · Physics 2014-11-20 L. P. Kaptari , B. Kampfer

We compute the electromagnetic form factors of the proton and neutron using lattice QCD with $N_f = 2 + 1 + 1$ twisted mass clover-improved fermions and quark masses tuned to their physical values. Three ensembles with lattice spacings of…

High Energy Physics - Lattice · Physics 2025-02-18 Constantia Alexandrou , Simone Bacchio , Giannis Koutsou , Bhavna Prasad , Gregoris Spanoudes

We present a parameterization of the non-collinear (virtual) Compton scattering tensor in terms of form factors, in which the Lorentz tensor associated with each form factor possesses manifest electromagnetic gauge invariance. The main…

High Energy Physics - Phenomenology · Physics 2008-02-03 Wei Lu

The electromagnetic polarizabilities of the nucleon are fundamental nucleon-structure observables that characterize its response to external electromagnetic fields. The neutron polarizabilities can be accessed from Compton-scattering data…

We discuss $(\pi^0,\eta,\eta')\to\gamma^*\gamma$ transition form factors using the light-front quark model. Our discussion includes the analysis of the mixing angles for $\eta-\eta'$. Our results for $Q^2…

High Energy Physics - Phenomenology · Physics 2016-03-23 Ho-Meoyng Choi , Chueng-Ryong Ji

The two-photon-exchange (TPE) effects in the process $e^+e^- \rightarrow \pi^+\pi^-$ at large momentum transfer are discussed within the perturbative QCD (pQCD). The contributions from the twist-2 and twist-3 distribution amplitudes (DAs)…

High Energy Physics - Phenomenology · Physics 2018-09-12 Hong-Yu Chen , Hai-Qing Zhou

The production of $\phi$ mesons in the reaction $e^{+}p \rightarrow e^{+} \phi p$ ($\phi \rightarrow K^{+}K^{-}$), for $7 < Q^2 < 25$ GeV$^2$ and for virtual photon-proton centre of mass energies ($W$) in the range 42-134 GeV, has been…

High Energy Physics - Experiment · Physics 2012-08-27 ZEUS Collaboration