1 99 7 DAMTP - 97 - 102 October 1997 Gauge Invariance and Factorisation in Exclusive Meson Production
نویسندگان
چکیده
The structure of the nonperturbative vector meson vertex function complicates the proof of the factorisation theorem for the reaction γ * p → V p. It leads to additional contributions but, in a simple model for the vertex function, gauge invariance ensures that they cancel and factorisation is preserved.
منابع مشابه
Elastic Meson Production – Factorisation and Gauge Invariance *
The factorisation of the hard amplitude for exclusive meson production in deep inelastic scattering is considered in the framework of a simple model. It is demonstrated explicitly how gauge invariance ensures the cancellation of non-factorising contributions.
متن کاملar X iv : h ep - p h / 97 11 22 7 v 1 4 N ov 1 99 7 TUM / T 39 - 97 - 28 Hard Exclusive Meson Production and Nonforward Parton Distributions ∗
We present an analysis of twist-2, leading order QCD amplitudes for hard exclusive leptoproduction of mesons in terms of double/nonforward parton distribution functions. After reviewing some general features of nonforward nucleon matrix elements of twist-2 QCD string operators, we propose a phenomenological model for quark and gluon nonforward distribution functions of nucleons. The correspondi...
متن کاملar X iv : h ep - t h / 97 05 21 6 v 1 2 8 M ay 1 99 7 On Gauge Invariance and Spontaneous Symmetry Breaking ∗
We show how the widely used concept of spontaneous symmetry breaking can be explained in causal perturbation theory by introducing a perturbative version of quantum gauge invariance. Perturbative gauge invariance, formulated exclusively by means of asymp-totic fields, is discussed for the simple example of Abelian U (1) gauge theory (Abelian Higgs model). Our findings are relevant for the elect...
متن کاملar X iv : h ep - t h / 97 12 17 5 v 1 1 7 D ec 1 99 7 GAUGE INVARIANCE FOR THE MASSIVE AXION
A massive gauge invariant formulation for scalar (φ) and antisymmetric (C mnp) fields with a topological coupling, which provides a mass for the axion field, is considered. The dual and local equivalence with the non-gauge invariant proposal is established, but on manifolds with non-trivial topological structure both formulations are not globally equivalent.
متن کاملar X iv : h ep - p h / 97 08 34 5 v 1 1 3 A ug 1 99 7 SLAC - PUB - 7604 July 1997 Exclusive Photon - Photon Processes ∗
Exclusive γγ → hadron pairs are among the most fundamental processes in QCD, providing a detailed examination of Compton scattering in the crossed channel. In the high momentum transfer domain (s, t, large, θ cm for t/s fixed), these processes can be computed from first principles in QCD, yielding important information on the nature of the QCD coupling α s and the form of hadron distribution am...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 1997