Quark fragmentation within an identified jet
Author(s)Stewart, Iain; Procura, Massimiliano
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We derive a factorization theorem that describes an energetic hadron h fragmenting from a jet produced by a parton i, where the jet invariant mass is measured. The analysis yields a “fragmenting jet function” Gih(s,z) that depends on the jet invariant mass s, and on the energy fraction z of the fragmentation hadron. We show that Gih can be computed in terms of perturbatively calculable coefficients, Jij(s,z/x), integrated against standard nonperturbative fragmentation functions, Djh(x). We also show that Sigmah∫dzGih(s,z) is given by the standard inclusive jet function Ji(s) which is perturbatively calculable in QCD. We use soft collinear effective theory and for simplicity carry out our derivation for a process with a single jet, B̅ -->Xhℓν̅ , with invariant mass mXh2≫ΛQCD2. Our analysis yields a simple replacement rule that allows any factorization theorem depending on an inclusive jet function Ji to be converted to a semi-inclusive process with a fragmenting hadron h. We apply this rule to derive factorization theorems for B̅ -->XKγ which is the fragmentation to a Kaon in b→sγ, and for e+e- -->(dijets)+h with measured hemisphere dijet invariant masses.
DepartmentMassachusetts Institute of Technology. Center for Theoretical Physics; Massachusetts Institute of Technology. Department of Physics; Massachusetts Institute of Technology. Laboratory for Nuclear Science
Physical Review D
American Physical Society
Procura, Massimiliano, and Iain W. Stewart. “Quark fragmentation within an identified jet.” Physical Review D 81.7 (2010): 074009. © 2010 The American Physical Society.
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