TY - JOUR

T1 - Resummation of large endpoint corrections to color-octet J/ψ photoproduction

AU - Fleming, Sean

AU - Leibovich, Adam K.

AU - Mehen, Thomas

PY - 2006

Y1 - 2006

N2 - An unresolved problem in J/ψ phenomenology is a systematic understanding of the differential photoproduction cross section, dσ/dz[γ+p→J/ψ+X], where z=Eψ/Eγ in the proton rest frame. In the nonrelativistic QCD (NRQCD) factorization formalism, fixed-order perturbative calculations of color-octet mechanisms suffer from large perturbative and nonperturbative corrections that grow rapidly in the endpoint region, z→1. In this paper, NRQCD and soft collinear effective theory are combined to resum these large corrections to the color-octet photoproduction cross section. We derive a factorization theorem for the endpoint differential cross section involving the parton distribution function and the color-octet J/ψ shape functions. A one-loop matching calculation explicitly confirms our factorization theorem at next-to-leading order. Large perturbative corrections are resummed using the renormalization group. The calculation of the color-octet contribution to dσ/dz is in qualitative agreement with data. Quantitative tests of the universality of color-octet matrix elements require improved knowledge of shape functions entering these calculations as well as resummation of the color-singlet contribution which accounts for much of the total cross section and also peaks near the endpoint.

AB - An unresolved problem in J/ψ phenomenology is a systematic understanding of the differential photoproduction cross section, dσ/dz[γ+p→J/ψ+X], where z=Eψ/Eγ in the proton rest frame. In the nonrelativistic QCD (NRQCD) factorization formalism, fixed-order perturbative calculations of color-octet mechanisms suffer from large perturbative and nonperturbative corrections that grow rapidly in the endpoint region, z→1. In this paper, NRQCD and soft collinear effective theory are combined to resum these large corrections to the color-octet photoproduction cross section. We derive a factorization theorem for the endpoint differential cross section involving the parton distribution function and the color-octet J/ψ shape functions. A one-loop matching calculation explicitly confirms our factorization theorem at next-to-leading order. Large perturbative corrections are resummed using the renormalization group. The calculation of the color-octet contribution to dσ/dz is in qualitative agreement with data. Quantitative tests of the universality of color-octet matrix elements require improved knowledge of shape functions entering these calculations as well as resummation of the color-singlet contribution which accounts for much of the total cross section and also peaks near the endpoint.

UR - http://www.scopus.com/inward/record.url?scp=33845359409&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33845359409&partnerID=8YFLogxK

U2 - 10.1103/PhysRevD.74.114004

DO - 10.1103/PhysRevD.74.114004

M3 - Article

AN - SCOPUS:33845359409

SN - 1550-7998

VL - 74

JO - Physical Review D - Particles, Fields, Gravitation and Cosmology

JF - Physical Review D - Particles, Fields, Gravitation and Cosmology

IS - 11

M1 - 114004

ER -