TY - JOUR
T1 - QCD constituent counting rules for neutral vector mesons
AU - Brodsky, Stanley J.
AU - Lebed, Richard
AU - Lyubovitskij, Valery E.
N1 - Funding Information:
This research was supported by the U.S. Department of Energy, Contract No.DE-AC02-76SF00515 (S.J.B.), by the U.S. National Science Foundation under Grant No.PHY-1403891 (R.F.L.), by the German Bundesministerium fur Bildung und Forschung (BMBF) under Project 05P2015-ALICE at High Rate (BMBF-FSP 202): Jet and fragmentation processes at ALICE and the parton structure of nuclei and structure of heavy hadrons, by CONICYT (Chile) PIA/Basal FB0821, by Tomsk State University Competitiveness Improvement Program, by the Russian Federation program Nauka (Contract No.0.1764.GZB.2017), and by Tomsk Polytechnic University Competitiveness Enhancement Program (Grant No.VIU-FTI-72/2017) (V.E.L.). SLAC-PUB-17184.
Funding Information:
We thank Feng-Kun Guo for suggesting the examination of the process . This research was supported by the U.S. Department of Energy, Contract No. DE–AC02–76SF00515 (S. J. B.), by the U.S. National Science Foundation under Grant No. PHY-1403891 (R. F. L.), by the German Bundesministerium für Bildung und Forschung (BMBF) under Project 05P2015—ALICE at High Rate (BMBF-FSP 202): “Jet and fragmentation processes at ALICE and the parton structure of nuclei and structure of heavy hadrons,” by CONICYT (Chile) PIA/Basal FB0821, by Tomsk State University Competitiveness Improvement Program, by the Russian Federation program “Nauka” (Contract No. 0.1764.GZB.2017), and by Tomsk Polytechnic University Competitiveness Enhancement Program (Grant No. VIU-FTI-72/2017) (V. E. L.). SLAC-PUB-17184.
Publisher Copyright:
© 2018 authors.
PY - 2018/2/1
Y1 - 2018/2/1
N2 - 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, 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=mV02, 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 V0 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 V0 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.
AB - 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, 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=mV02, 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 V0 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 V0 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.
UR - http://www.scopus.com/inward/record.url?scp=85043361007&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85043361007&partnerID=8YFLogxK
U2 - 10.1103/PhysRevD.97.034009
DO - 10.1103/PhysRevD.97.034009
M3 - Article
AN - SCOPUS:85043361007
SN - 2470-0010
VL - 97
JO - Physical Review D
JF - Physical Review D
IS - 3
M1 - 034009
ER -