Target normal spin asymmetry and charge asymmetry foreμelastic scattering and the crossed processes

Abstract

Two kinds of asymmetry arise from the interference of the Born amplitude and the box-type amplitude corresponding to two virtual photons exchange, namely charge-odd and one spin asymmetries. In case of unpolarized particles the charge-odd correlation is calculated. It can be measured in combination of electron muon and positron muon scattering experiments. The forward-backward asymmetry is the corresponding quantity which can be measured for the crossed processes. In the case of polarized muon the one-spin asymmetry for annihilation and scattering channels has been calculated. The additional structure function arising from the interference is shown to suffer from infrared divergencies. The background due to electroweak interaction is discussed. PACS numbers:

Structure function method applied to polarized and unpolarized electron-proton scattering: A solution of theGE(p)/GM(pBystritskiy1, Kuraev2, Tomasi–Gustafsson3 2007Phys. Rev. CSelf Cite726590View full textAdd to dashboardCite

“…[16], where the process e + e − → µ + + µ − and the crossed process were calculated and shown to be of the order of 1%. The QED case can be considered as an upper limit for 2γ effects in electron proton scattering, due to two reasons, at least: the proton electromagnetic [25].…”

Two photon exchange for exclusive pion electroproduction

“…The three-point scalar integral C 0 ({k i , m i }, {k j , m j }) in Eq. (14) was evaluated both using an approximated expression (m i ≪ m j ) taken from [22], and exactly with the help of the package LoopTools [19]. The explicit expression for this integral reads as follows:…”

Structure function approach in QED for high energy processes

“…In our considerations we omit FD with two virtual exchanged photons due to the cancellation of such contributions when one includes the amplitude corresponding to soft-photon emission between electron and muon blocks. The details of this ®up-down cancellation¯, which holds in LLA, were discussed in [34] and refs. therein.…”