Title: QCD constituent counting rules for neutral vector mesons

Abstract

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 V⁰ in e ⁺ e ^- annihilation, processes in which the V⁰ can couple via intermediate photons. In the case of a (narrow) real V⁰, the photon virtuality is fixed to a precise value s₁ = m2V₀, thus treating the V⁰ as a single fundamental particle. Each real V⁰ thus contributes to the constituent counting rules with NV0 = 1 . In effect, the leading operator underlying the Vmore » 0 has twist 1. Thus, in the specific physical case of single or double on-shell V⁰ 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 V⁰ is not coupled through an elementary photon field, and then the leading-twist interpolating operator has twist NV₀ = 2 . Analogous effects appear in pp scattering processes.« less

Authors:

Brodsky, Stanley J.; Lebed, Richard F.; Lyubovitskij, Valery E.

Publication Date:

Thu Feb 08 00:00:00 EST 2018

Research Org.:

SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)

Sponsoring Org.:

USDOE; National Science Foundation (NSF)

OSTI Identifier:

1419912

Alternate Identifier(s):

OSTI ID: 1424719

Grant/Contract Number:  

DE–AC02–76SF00515; AC02-76SF00515; PHY-1403891; BMBF-FSP 202; 0.1764.GZB.2017; VIU-FTI-72/2017

Resource Type:

Published Article

Journal Name:

Physical Review D

Additional Journal Information:

Journal Name: Physical Review D Journal Volume: 97 Journal Issue: 3; Journal ID: ISSN 2470-0010

Publisher:

American Physical Society

Country of Publication:

United States

Language:

English

Subject:

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS