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Title: QCD constituent counting rules for neutral vector mesons

QCD constituent counting rules define the scaling behavior of exclusive hadronic scattering and electromagnetic scattering amplitudes at high momentum transfer in terms of the total number of fundamental constituents in the initial and final states participating in the hard subprocess. The scaling laws reflect the twist of the leading Fock state for each hadron and hence the leading operator that creates the composite state from the vacuum. Thus, the constituent counting scaling laws can be used to identify the twist of exotic hadronic candidates such as tetraquarks and pentaquarks. Effective field theories must consistently implement the scaling rules in order to be consistent with the fundamental theory. Here in this paper, we examine how one can apply constituent counting rules for the exclusive production of one or two neutral vector mesons V 0 in e + e - annihilation, processes in which the V 0 can couple via intermediate photons. In the case of a (narrow) real V 0, the photon virtuality is fixed to a precise value s 1 = m2V 0, thus treating the V 0 as a single fundamental particle. Each real V 0 thus contributes to the constituent counting rules with NV0 = 1 . Inmore » effect, the leading operator underlying the V 0 has twist 1. Thus, in the specific physical case of single or double on-shell V 0 production via intermediate photons, the predicted scaling from counting rules coincides with vector-meson dominance (VMD), an effective theory that treats V 0 as an elementary field. However, the VMD prediction fails in the general case where the V 0 is not coupled through an elementary photon field, and then the leading-twist interpolating operator has twist NV 0 = 2 . Analogous effects appear in pp scattering processes.« less
 [1] ;  [2] ;  [3]
  1. SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., CA (United States)
  2. Arizona State Univ., Tempe, AZ (United States). Dept. of Physics
  3. Univ. Tubingen, Tubingen (Germany). Kepler Center for Astro and Particle Physics, Inst. fur Theoretische Physik; Univ. Tecnica Federico Santa María, Valparaiso, (Chile); Tomsk State Univ., Tomsk (Russia). Dept. of Physics
Publication Date:
Grant/Contract Number:
AC02-76SF00515; PHY-1403891; BMBF-FSP 202; 0.1764.GZB.2017; VIU-FTI-72/2017
Accepted Manuscript
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 97; Journal Issue: 3; Journal ID: ISSN 2470-0010
American Physical Society (APS)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE; National Science Foundation (NSF)
Country of Publication:
United States
OSTI Identifier: