Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userMoments of the 3--loop corrections to the heavy flavor contribution to $F_2(x,Q^2)$ for $Q^2gg m^2$
139
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We calculate moments of the $O(alpha_s^3)$ heavy flavor contributions to the Wilson coefficients of the structure function $F_2(x,Q^2)$ in the region $Q^2gg m^2$. The massive Wilson coefficients are obtained as convolutions of massive operator matrix elements (OMEs) and the known light flavor Wilson coefficients. The calculation of moments of the massive OMEs involves a first independent recalculation of moments of the fermionic contributions to all 3--loop anomalous dimensions of the unpolarized twist--2 local composite operators stemming from the light--cone expansion cite{url}.
rate research
Read More
The twist--2 heavy flavor contributions to the polarized structure function $g_2(x,Q^2)$ are calculated. We show that this part of $g_2(x,Q^2)$ is related to the heavy flavor contribution to $g_1(x,Q^2)$ by the Wandzura--Wilczek relation to all orders in the strong coupling constant. Numerical results are presented.
The logarithmic contributions to the massive twist-2 operator matrix elements for deep-inelastic scattering are calculated to $O(alpha_s^3)$for general values of the Mellin variable $N$.
Light-front Hamiltonian dynamics is used to relate low-energy constituent quark models to deep inelastic unpolarized structure functions of the nucleon. The approach incorporates the correct Pauli principle prescription consistently and it allows a transparent investigation of the effects due to the spin-dependent SU(6)-breaking terms in the quark model Hamiltonian. Both Goldstone-boson-exchange interaction and hyperfine-potential models are discussed in a unified scheme and a detailed comparison, between the two(apparently) different potential prescriptions, is presented.
Parity-violating deep inelastic scattering (PVDIS) has been proposed as an important new tool to extract the flavor and isospin dependence of parton distributions in the nucleon. We discuss finite-Q^2 effects in PVDIS asymmetries arising from subleading kinematical corrections and longitudinal contributions to the photon-Z interference. For the proton, these need to be accounted for in order to accurately extract the d/u ratio at large x; for the deuteron they are important to consider when searching for evidence of charge symmetry violation in parton distributions or signals for physics beyond the standard model. We further explore the dependence of PVDIS asymmetries for polarized targets on the u and d helicity distributions at large x.
We derive a second-order linear differential equation for the leading order gluon distribution function G(x,Q^2) = xg(x,Q^2) which determines G(x,Q^2) directly from the proton structure function F_2^p(x,Q^2). This equation is derived from the leading order DGLAP evolution equation for F_2^p(x,Q^2), and does not require knowledge of either the individual quark distributions or the gluon evolution equation. Given an analytic expression that successfully reproduces the known experimental data for F_2^p(x,Q^2) in a domain x_min<=x<=x_max, Q_min^2<=Q^2<=Q_max^2 of the Bjorken variable x and the virtuality Q^2 in deep inelastic scattering, G(x,Q^2) is uniquely determined in the same domain. We give the general solution and illustrate the method using the recently proposed Froissart bound type parametrization of F_2^p(x,Q^2) of E. L. Berger, M. M. Block and C-I. Tan, PRL 98, 242001, (2007). Existing leading-order gluon distributions based on power-law description of individual parton distributions agree roughly with the new distributions for x>~10^-3 as they should, but are much larger for x<~10^-3.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
