Electroweak boson production in double parton scattering

Abstract

We study the W + W − and Z 0 Z 0 electroweak boson production in double parton scattering using QCD evolution equations for double parton distributions. In particular, we analyze the impact of splitting terms in the evolution equations on the double parton scattering cross sections. Unlike the standard terms, the splitting terms are not suppressed for large values of the relative momentum of two partons in the double parton scattering. Thus, they play an important role which we discuss in detail for the single splitting contribution to the cross sections under the study.

Heavy--Light Mesons in Minkowski Space

“…The mixing parameter y allows to dial continuously between a scalar-plus-pseudoscalar structure, suggested recently in [7] due to chiral-symmetry constraints, and a vector structure, while preserving the same nonrelativistic limit. The precise Lorentz structure of the confining interaction is not known, and by fitting the y parameter from the mesonic spectra, some further information can be gained.…”

“…In the CST formalism, the requirements of chiral symmetry can also be satisfied, which is imperative for a realistic description of the pion. In particular, reference [7] shows how confining forces with a Lorentz scalar component, which have been suggested to dominate [8][9][10], are made consistent with spontaneous chiral symmetry breaking (SχSB).…”

How to impose initial conditions for QCD evolution of double parton distributions?

“…A phenomenological discussion of the case q = 0 in the context of evolution equations, discussed below, can be found in [13,41].…”

Perturbative and nonperturbative correlations in double parton distributions

“…The problem of specifying the initial correlation conditions for the evolution equations, which would obey exactly these sum rules and have the correct asymptotic behavior near the kinematical boundaries, has been extensively studied in Refs. [53,[58][59][60][61][62]. Fortunately, the explicit form of evolution equation solutions allows us to answer the question: which correlations (perturbative (10) or nonperturbative (9)) are more significant at sufficiently large hard scale.…”