The deep Compton scattering: Single photon spectrum and photon-hadron correlations beyond leading logarithms

Largep T double photon production in hadronic collisions-beyond leading logarithm QCD calculation

“…The technique of such calculations is inspired from the method we have already developed in calculating BLL corrections to the double inclusive cross-section da(~P-~hX)/dprdydx h for observing a large Pr photon together with a hadron h in the opposite hemisphere with fraction Xn of the trigger transverse momentum [7].…”

“…where x~ and x2 are given by (12) In order to extract the genuine higher order corrections K~r and K'o, from the perturbative expressions of k~ and k'0,, one has to use the implications of factorization and as explained at length in [12,7], introduce a choice of definitions for the distribution functions.…”

“…It follows closely [7]. The invariants a~, b~ in terms of which the squared matrix element I M~ol 2 is calculated are defined as usual:…”

“…As early as 1971, Berman et al [3] discussed the QED annihilation subprocess qq~? 7 which has the remarkable feature of being proportional to the 4th power of the quark charge. This observation stimulated further interest in studying and measuring 2-7 production in hadronic collisions.…”

“…Calculations are performed along the same line as for the corrections to the double inclusive cross-section a(?p~Thx) [7]. We shall consider the cross-section da/dpr, dyl dz where Pr,, Yl label the transverse momentum and rapidity of the trigger 7 in the hadron hadron CMS z is defined as: z = -PTdPrfPr?, PT2…”