A precise extraction of R=σL/σT from a global analysis of the SLAC deep inelastic e-p and e-d scattering cross sections

Abstract

We report the extraction of R= uLIT from a global analysis of eight .* SLAC deep inelastic experiments on e-p and e-d scattering performed between 1970 and 1985. Values of RP, Rd, and Rd-Rp are determined over the entire SLAC kinematic range: 0.1 5 x 5 0.9 and 0.6 5 Q2 5 20.0 (GeV/c)2. We find that RP = Rd, as expected in &CD. Measured values of R(x, Q2) are larger than predictions based on perturbative QCD and on QCD with the inclusion of kinematic target mass terms, indicating that dynamical higher twist effects may be important in the SLAG kinematic range.

Finite-Q2corrections to parity-violating DIS

“…Including the R γ ratio from Ref. [19] reduces the effect down to ≈ 1 − 3% over the same range, with an uncertainty of ≈ ±0.5% for x < ∼ 0.8, and ≈ 1% at larger x. This R γZ .…”

“…While data and phenomenological parametrizations are available for R γ [19][20][21], currently no empirical information exists on R γZ . In our numerical estimates below, we shall consider a range of possible behaviors for R γZ and examine its effect on A PV .…”

“…For Y 3 , the Bjorken limit result (R γ = 0, r 2 = 1) is given by the dotted curve, the dashed curve has cases we use R γ from the parametrization of Ref. [19]. The results with the parametrization of Ref.…”

Determination of the longitudinal proton structure function FL(x,Q2) at low x

“…have been made by v arious xed target lepton-hadron scattering experiments at higher x values [4,5]. This paper presents the rst determination of F L (x; Q 2 ) at HERA in the deep inelastic region of 8:5 Q 2 35 GeV 2 and very small x values between 1:3 10 4 and 5:5 10 4 .…”

“…This method combines the positron with the hadronic measurement by de ning Q 2 = E 0 2 e sin 2 e 1 y y = y h 1 + y h y e ; (4) which avoids the resolution degradation of y e at low y. Here y h = P i (E i p z;i ) 2E e ; (5) where E i and p z;i are the energy and longitudinal momentum component of a particle i.…”