Related papers: Physical Anomalous Dimensions at Small $x$
Measurements involving the gluon spin density, Delta G=G++ - G+-, can play an important role in the quantitative understanding of proton structure. To demonstrate this, we show that the shape of the gluon asymmetry, A(x,t)=Delta…
The deuteron deep inelastic unpolarized structure function F_2^D is calculated using the Wilson operator product expansion method. The long distance behaviour, related to the deuteron bound state properties, is evaluated using the…
We present a physical model for polarized and unpolarized structure functions and parton density functions (PDFs) of the proton and the neutron. It reproduces the data on F_2^p(x,Q^2) for 0.00001<x<1 and 2.5<Q^2<5000 GeV^2,…
We study the anomalous dimensions and coefficient functions generated by the BFKL equation in 4+2 epsilon dimensions, by investigating both running coupling effects, and the inclusion of the full next-to-leading kernel. After generalising…
We calculate the gluon gravitational form factors (GFFs) of the proton using a light-front spectator model based on soft-wall AdS/QCD, where the active parton is a gluon. The model parameters are determined by fitting the unpolarized gluon…
The perturbative QCD predictions concerning deep inelastic scattering at low $x$ are summarized. The theoretical framework based on the leading log $1/x$ resummation and $k_t$ factorization theorem is described and some recent developments…
In this paper we re-analyse the situation with the shadowing corrections (SC) in QCD for the proton deep inelastic structure functions. We reconsider the Glauber - Mueller approach for the SC in deep inelastic scattering (DIS) and suggest a…
We obtain the gluon parton distribution functions (PDFs) in the proton within the extended light-front holographic QCD framework, where the proton couples with the spin-two Pomeron in Anti-de Sitter space, together with constraints imposed…
We present parametrizations for the proton structure function $F_2$ in the next to leading order in perturbative QCD. The calculations show that the dominant term to $F_2(x,Q^2)$ should grow as $x^{-\ls}$ for small $x$ values, with the…
The spin-averaged structure function of the neutron, F_2^n, is extracted from recent deuteron data, taking into account the small but significant corrections due to nuclear effects in the deuteron. At small x, the F_2D/F_2p ratio measured…
The use of extra dimensional scenarios as models for neutrino mass affects many low energy observables. We consider the implications of virtual bulk neutrinos in precision experiments of the anomalous magnetic moments of the muon and the…
We construct a simple two-phase model of the nucleon structure functions valid for both small and large Q^2 and in the broad range of Bjorken x. The model incorporates hadron dominance at small x and Q^2 and parton model at large Q^2. The…
In a companion paper we studied field theory in the presence of a physical observer with quantum dynamics. Here we describe the most striking consequence of this assumption: new gauge and diff anomalies arise. The relevant cocycles depend…
Understanding the infrared sensitivity of perturbative predictions in QCD is important for assessing the magnitude of possible non-perturbative power corrections to processes with large momentum transfer. In renormalon models, this…
It is shown that the previously noted extreme perturbative instability of the longitudinal structure function F_L(x,Q^2) in the small Bjorken-$x$ region, is a mere artefact of the commonly utilized `standard' gluon distributions. In…
We present an updated extraction of the proton electromagnetic form factor ratio, mu_p G_E/G_M, at low Q^2. The form factors are sensitive to the spatial distribution of the proton, and precise measurements can be used to constrain models…
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 differences are discussed between various next-to-leading order prescriptions for the QCD evolution of parton densities and structure functions. Their quantitative impact is understood to an accuracy of 0.02\%. The uncertainties due to…
Quark-hadron duality is studied in a systematic way for both the unpolarized and polarized structure functions, by taking into account all the available data in the resonance region.In both cases, a detailed perturbative QCD based analysis…
The anomalous dimensions of the gluon and ghost fields as well as the ghost-ghost-gluon and quark-quark-gluon vertexes are analytically computed in pQCD. Taken together with already available anomalous dimensions of the coupling constant,…