The challenge of smallx

Abstract

We review the current understanding of the behaviour of inclusive cross sections at small x and large Q2 in terms of Altarelli-Parisi evolution, the BFKL equation, and Regge theory, asking in particular to what extent they are mutually consistent.

Klein-Nishina effects in the spectra of non-thermal sources immersed in external radiation fields

“…Additionally, PSR B1259-63 was recently identified as a TeV source . Ball & Kirk (2000) envisaged two scenarios for production of high-energy radiation in such systems: Comptonization of the radiation field of the companion luminous star directly by the pulsar ultrarelativistic wind (i.e. a bulk Compton scenario) or by particles accelerated in the terminal wind shock formed due to the confinement of the pulsar wind by the wind from the companion star.…”

A phenomenological solution small x to the longitudinal structure function dynamical behavior

“…In this limit, the gluon distribution will become large, so its contribution to the evolution of the parton distribution becomes dominant. Therefore the gluon distribution has a rapid rise behavior small x, that is xg(x, Q 2 ) = f g x −λ , where λ is corresponding to the hard-Pomeron intercept [30][31][32][33]62]. Exploiting the small-x asymptotic behavior for the gluon distribution and charm structure functions to the evolution equations of the gluonic longitudinal structure function and charm longitudinal structure function respectively (Eqs.23, 27), evolution of the longitudinal structure function at small-x can be found as…”

“…In Figs.1-3, we present the small x behavior of the F L structure function according to the evolution equation (28) (heavy + gluonic) of longitudinal structure function with results of DL [30][31][32][33]62] and CD models [63]. In the right hand side, F…”

“…1−z and µ is the mass factorization scale, which has been put equal to the renormalization scales µ 2 = 4m [30][31][32][33]62] and CD [63] models respectively. right: The total FL compared with kT factorization [64] and H1 data [54] with total error.…”

Introduction to diffractive photoprocesses

“…In leading order this approach predicted the hard pomeron intercept with apparent success, but it runs into serious difficulties beyond leading order. This topic will be discussed by Ross [19] while a succinct comparison of the Regge, BFKL and DGLAP approaches and their relation to each other may be found in the recent review of Ball and Landshoff [20].…”