منابع مشابه
Hard Exclusive Electroproduction of Pions ∗
We investigate the exclusive electroproduction of π mesons from nucleons. To leading twist, leading order αs accuracy the corresponding production amplitude can be decomposed into pseudovector and pseudoscalar parts. Both can be expressed in terms of quark double distribution functions of the nucleon. While the pseudovector contribution is connected to ordinary polarized quark distributions, th...
متن کاملHard exclusive electroproduction of two pions and their resonances
We study the hard exclusive production of two pions in the virtual photon fragmentation region with various invariant masses including the resonance region. The amplitude is expressed in terms of two-pion light cone distribution amplitudes (2πDA’s). We derive dispersion relations for these amplitudes, which enables us to fix them completely in terms of ππ scattering phases and a few low-energy ...
متن کاملFactorization for Hard Exclusive Electroproduction
The processes discussed in this talk were ep → eMp, ep → eγp, and ep → eμμp, all in the deep-inelastic region where Q is large. The factorization theorems that I will discuss provide a sound basis for the phenomenology of these processes, which was discussed extensively at this workshop. They express the amplitudes for the processes in terms of operator matrix elements and perturbatively calcul...
متن کاملTransverse-Target Single-Spin Azimuthal Asymmetry in Hard Exclusive Electroproduction of Single Pions at HERMES
We present the analysis of data taken in the years 2002-2004 with the 27.56 GeV positron beam of the HERA storage ring at DESY and the internal transversely polarised hydrogen fixed target of the HERMES experiment. Events with a scattered positron and a produced pion are selected. Exclusive production of single pions, e+p → e+′nπ+, is ensured by requiring the missing mass in the event to be equ...
متن کاملHard Exclusive Electroproduction of Two Pions off Proton and Deuteron at HERMES
Exclusive electroproduction of π+π− pairs off hydrogen and deuterium targets has been studied with the HERMES experiment. The angular distribution of the π+ in the π+π− rest system has been studied in the invariant mass range 0.3 < mππ < 1.5 GeV. Theoretical models derived in the framework of the Generalized Parton Distributions show that this angular distribution receives only contributions fr...
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ژورنال
عنوان ژورنال: The European Physical Journal C
سال: 1999
ISSN: 1434-6044,1434-6052
DOI: 10.1007/s100529900045