Related papers: Virtual photon structure functions and positivity …
We investigate the positivity constraints for the structure functions of both virtual and real photon. From the Cauchy-Schwarz inequality we derive three positivity conditions for the general virtual photon case, which reduce, in the real…
Photon structure functions in supersymmetric QCD are investigated in terms of the parton model where squark contributions are evaluated. We calculate the eight virtual photon structure functions by taking the discontinuity of the squark…
We discuss the perturbatively calculable virtual photon structure functions. First we present the framework for analyzing the structure functions of the virtual photon and derive a first moment of $g_1^\gamma$ of the virtual photon. We then…
The implications of the positivity constraint, $|g_1^{\gamma(P^2)}(x,Q^2)| \leq F_1^{\gamma(P^2)}(x,Q^2)$, on the presently unknown spin--dependent structure function $g_1^{\gamma(P^2)}(x,Q^2)$ of real and virtual photons are studied at…
We investigate the one-gluon-exchange ($\alpha \alpha_s$) corrections to the real photon structure functions $W_{TT} $, $W_{LT}$, $W_{TT}^{a} $ and $W_{TT}^\tau$ in the massive parton model. We employ a technique based on the Cutkosky rules…
The implications of the positivity constraint on the presently unknown polarized structure function of the photon, $g_1^{\gamma}(x,Q^2)$, are studied in detail. In particular the non-trivial consequences of this constraint,…
The unpolarized virtual photon structure functions $F_2^\gamma(x,Q^2,P^2)$ and $F_L^\gamma(x,Q^2,P^2)$ are investigated in perturbative QCD for the kinematical region $\Lambda^2 \ll P^2 \ll Q^2$, where $-Q^2(-P^2)$ is the mass squared of…
The structure functions F_2 and F_1 of real photon at low virtualities are calculated in the framework of chiral perturbation theory (ChPT) in the zero and first order of ChPT. It is assumed that the virtuality of hard projectile photon Q^2…
The photon structure function is a useful testing ground for QCD. It is perturbatively computable apart from a contribution from what is usually called the hadronic component of the photon. There have been many proposals for this…
We present a systematic analysis of the polarised and unpolarised processes $e^+ ~e^- \rightarrow e^+ ~e^- X$ in the deep inelastic limit and study the effects of target photon mass (virtuality) on the photon structure functions. The effect…
We evolve virtual photon parton densities up to the SUSY threshold and higher using coupled inhomogeneous DGLAP differential equations. Reliable input parameterizations were available from the c-quark threshold. Limited $P^2$ ( target…
The virtual photon structure function $g_1^{\gamma}(x,Q^2,P^2)$, which can be obtained in polarized $e^{+}e^{-}$ colliding-beam experiments, is investigated for $\Lambda^2 \ll P^2 \ll Q^2$, where $-Q^2$ ($-P^2$) is the mass squared of the…
We study the virtual photon structure functions from gauge/string duality. If the Bjorken variable x is not small, supergravity approximation becomes good in dual string theory. We calculate the virtual photon structure functions at large…
Polarized photon structure can be studied in the future polarized $e^{+}e^{-}$ colliding-beam experiments. We investigate the spin-dependent structure function of the virtual photon $g_1^{\gamma}(x,Q^2,P^2)$, in perturbative QCD for…
In the framework of the perturbative QCD we investigate heavy particle mass effects on the unpolarized and polarized photon structure functions, $F_2^\gamma$ and $g_1^\gamma$, respectively. We present our basic formalism to treat heavy…
We discuss the structure functions and the parton distributions in the virtual photon target, both polarized and unpolarized, beyond the leading order in QCD. We study the factorization-scheme dependence of the parton distributions.
We investigate the heavy quark mass effects in the virtual photon structure functions $F_{2}^{\gamma}(x, Q^2, P^2)$ and $F_{L}^{\gamma}(x, Q^2, P^2)$ in the framework of the mass-independent renormalization group equation (RGE). We study a…
We investigate the twist-3 effects in the polarized virtual photon structure. The structure functions $g_1^\gamma$ and $g_2^\gamma$ of polarized photon could be experimentally studied in the future polarized $ep$ or $e^+e^-$ colliders. The…
We investigated top quark effects on virtual photon structure functions by pQCD. We include the top quark mass effects on the virtual photon structure function with the quark parton model and with the operator product expansion up to the…
We investigate twist-3 effects in the polarized virtual photon. The structure function $g_2^\gamma$, which exists only for the virtual photon target and can be measured in future polarized $e^+ e^-$ collider experiments, receives both…