scholarly journals On the Interplay between Q2 and t Dependences in Exclusive Diffractive Production of Real Photons and Vector Mesons in ep Collisions

2012 ◽  
Vol 57 (12) ◽  
pp. 1197
Author(s):  
R. Fiore ◽  
L.L. Jenkovszky ◽  
A. Lavorini ◽  
V.K. Magas
Keyword(s):  
Mass Shell ◽  
Scattering Amplitude ◽  
Meson Production ◽  
Deeply Virtual Compton Scattering ◽  
Virtual Compton Scattering ◽  
Photon Virtuality ◽  
Vector Meson Production ◽  
Diffractive Production ◽  
Mandelstam Analyticity ◽  
Free Parameters

We show how the familiar phenomenological way of combining the Q2 (photon virtuality) and t (squared momentum transfer) dependences of the scattering amplitude in Deeply Virtual Compton Scattering (DVCS) [1, 2] and Vector Meson Production (VMP) [2] processes can be understood in an off-mass-shell generalization of dual amplitudes with Mandelstam analyticity [3]. By comparingdifferent approaches, we managed also to constrain the numerical values of the free parameters.

scholarly journals VECTOR MESON PRODUCTION AT HERA

2005 ◽  
Vol 20 (02n03) ◽  
pp. 436-444
Author(s):  
◽  
DOROTA SZUBA
Keyword(s):  
Vector Meson ◽  
Meson Production ◽  
Strong Interactions ◽  
Centre Of Mass ◽  
Mass Energy ◽  
Photon Virtuality ◽  
Vector Meson Production ◽  
Diffractive Production ◽  
Low Mass ◽  
Hadronic System

The diffractive production of vector mesons ep→eVMY, with VM=ρ0, ω, ϕ, J/ψ, ψ′ or ϒ and with Y being either the scattered proton or a low mass hadronic system, has been extensively investigated at HERA. HERA offers a unique opportunity to study the dependences of diffractive processes on different scales: the mass of the vector meson, mVM, the centre-of-mass energy of the γp system, W, the photon virtuality, Q2 and the four-momentum transfer squared at the proton vertex, |t|. Strong interactions can be investigated in the transition from the hard to the soft regime, where the confinement of quarks and gluons occurs.

scholarly journals Studying neutron structure at Jefferson Lab through electron scattering off the deuteron, using CLAS12 and the Central Neutron Detector

2020 ◽  
Vol 1643 (1) ◽  
pp. 012191
Author(s):  
Paul Naidoo ◽  
Daria Sokhan ◽  
Pierre Chatagnon ◽  
Silvia Niccolai ◽  
Katheryne Price
Keyword(s):  
Neutron Detector ◽  
Meson Production ◽  
Deeply Virtual Compton Scattering ◽  
Virtual Compton Scattering ◽  
High Energy ◽  
Neutral Meson ◽  
Deuteron Target ◽  
Jefferson Lab ◽  
3D Tomography ◽  
Large Acceptance

Abstract Generalised Parton Distributions (GPDs) offer a way of imaging nucleons through 3D tomography. They can be accessed experimentally in processes such as Deeply Virtual Compton Scattering (DVCS) and Deeply Virtual Meson Production (DVMP), where a high energy electron scatters from a quark inside a nucleon and a high energy photon or meson is produced as a result. Jefferson Lab has recently completed its energy upgrade and Hall B houses the new, large-acceptance CLAS12 detector array optimised for measurements of DVCS and DVMP in the newly accessible kinematic regime. Measurements on the proton and neutron are complementary and both are necessary to facilitate access to the full set of GPDs and enable their flavour separation. Neutron DVCS and DVMP are possible with the use of a deuteron target – the first CLAS12 experiment with which has started taking data this year. To enable exclusive reconstruction of DVCS and neutral-meson DVMP, a dedicated detector for recoiling neutrons – the Central Neutron Detector (CND) – was integrated into CLAS12. We present the first CLAS12 deuteron-target experiment, with a focus on the performance of the CND.

scholarly journals Program of COMPASS-II at CERN

2015 ◽  
Vol 37 ◽  
pp. 1560063 ◽  
Author(s):  
A. Sandacz
Keyword(s):  
Compton Scattering ◽  
Charged Pion ◽  
Meson Production ◽  
Deeply Virtual Compton Scattering ◽  
Virtual Compton Scattering ◽  
Compass Collaboration ◽  
Liquid Hydrogen Target ◽  
Muon Scattering ◽  
Hydrogen Target ◽  
Polarized Protons

COMPASS collaboration has started in 2012 a five-year program of new measurements, which are outlined in the 'COMPASS-II' proposal. The two new major projects of the proposal are measurements of polarized Drell-Yan process in π- scattering off transversely polarized protons and studies of GPDs via measurements of Deeply Virtual Compton Scattering and Hard Exclusive Meson Production in muon scattering off a liquid hydrogen target. In addition, high statistics SIDSI measurements with muon beams and a study of charged pion and kaon polarizabilities via Primakoff reactions with hadron beams are also foreseen as a part of this program.

scholarly journals Deeply virtual Compton scattering amplitude in the parton model

2000 ◽  
Vol 491 (1-2) ◽  
pp. 96-100 ◽  
Author(s):  
M. Penttinen ◽  
M.V. Polyakov ◽  
A.G. Shuvaev ◽  
M. Strikman
Keyword(s):  
Compton Scattering ◽  
Scattering Amplitude ◽  
Deeply Virtual Compton Scattering ◽  
Virtual Compton Scattering ◽  
Parton Model

PARTONIC PICTURE OF GTMDS

2014 ◽  
Vol 25 ◽  
pp. 1460009 ◽  
Author(s):  
SIMONETTA LIUTI ◽  
ABHA RAJAN ◽  
AURORE COURTOY ◽  
GARY R. GOLDSTEIN ◽  
J. OSVALDO GONZALEZ HERNANDEZ
Keyword(s):  
Angular Momentum ◽  
Compton Scattering ◽  
Orbital Angular Momentum ◽  
Scattering Amplitude ◽  
Final State Interaction ◽  
Deeply Virtual Compton Scattering ◽  
Virtual Compton Scattering ◽  
Matrix Elements ◽  
Final State ◽  
Wigner Distributions

We argue that due to parity constraints, the helicity combination of the purely momentum space counterparts of the Wigner distributions — the generalized transverse momentum distributions — that describes the configuration of an unpolarized quark in a longitudinally polarized nucleon, can enter the deeply virtual Compton scattering amplitude only through matrix elements involving a final state interaction. The relevant matrix elements in turn involve light cone operators projections in the transverse direction, or they appear in the deeply virtual Compton scattering amplitude at twist three. Orbital angular momentum or the spin structure of the nucleon was a major reason for these various distributions and amplitudes to have been introduced. We show that twist three contributions to deeply virtual Compton scattering provide observables related to orbital angular momentum.

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