On the interface between perturbative and nonperturbative QCD
The QCD running coupling $$\alpha_s(Q^2)$$ sets the strength of the interactions of quarks and gluons as a function of the momentum transfer $Q$. The $Q^2$ dependence of the coupling is required to describe hadronic interactions at both large and short distances. In this article we adopt the light-front holographic approach to strongly-coupled QCD, a formalism which incorporates confinement, predicts the spectroscopy of hadrons composed of light quarks, and describes the low-$Q^2$ analytic behavior of the strong coupling $$\alpha_s(Q^2)$$. The high-$Q^2$ dependence of the coupling $$\alpha_s(Q^2)$$ is specified by perturbative QCD and its renormalization group equation. The matching of the high and low $Q^2$ regimes of $$\alpha_s(Q^2)$$ then determines the scale $$Q_0$$ which sets the interface between perturbative and nonperturbative hadron dynamics. The value of $$Q_0$$ can be used to set the factorization scale for DGLAP evolution of hadronic structure functions and the ERBL evolution of distribution amplitudes. We discuss the scheme-dependence of the value of $$Q_0$$ and the infrared fixed-point of the QCD coupling. Our analysis is carried out for the $$\bar{MS}$$, $$g_1$$, $MOM$ and $V$ renormalization schemes. Our results show that the discrepancies on the value of $$\alpha_s$$ at large distance seen in the literature can be explained by different choices of renormalization schemes. Lastly, we also provide the formulae to compute $$\alpha_s(Q^2)$$ over the entire range of space-like momentum transfer for the different renormalization schemes discussed in this article.
- Authors:
-
[1]
; [2]
; [3]
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- SLAC National Accelerator Lab., Menlo Park, CA (United States)
- Univ. of Costa Rica, San Pedro (Costa Rica)
- Publication Date:
- Report Number(s):
- JLAB-PHY-16-2198; SLAC-PUB-16449; DOE/OR/23177-3646; arXiv:1601.06568
Journal ID: ISSN 0370-2693; PII: S037026931630048X
- Grant/Contract Number:
- AC05-06OR23177; AC02-76SF00515; SLAC-PUB-16449
- Type:
- Published Article
- Journal Name:
- Physics Letters. Section B
- Additional Journal Information:
- Journal Name: Physics Letters. Section B; Journal ID: ISSN 0370-2693
- Publisher:
- Elsevier
- Research Org:
- Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
- Sponsoring Org:
- USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
- OSTI Identifier:
- 1245477
- Alternate Identifier(s):
- OSTI ID: 1245546; OSTI ID: 1249326