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Title: New Methods in Non-Perturbative QCD

Abstract

In this work, we investigate the properties of quantum chromodynamics (QCD), by using newly developing mathematics and physics formalisms. Almost all of the mass in the visible universe emerges from a quantum chromodynamics (QCD), which has a completely negligible microscopic mass content. An intimately related issue in QCD is the quark confinement problem. Answers to non-perturbative questions in QCD remained largely elusive despite much effort over the years. It is also believed that the usual perturbation theory is inadequate to address these kinds of problems. Perturbation theory gives a divergent asymptotic series (even when the theory is properly renormalized), and there are non-perturbative phenomena which never appear at any order in perturbation theory. Recently, a fascinating bridge between perturbation theory and non-perturbative effects has been found: a formalism called resurgence theory in mathematics tells us that perturbative data and non-perturbative data are intimately related. Translating this to the language of quantum field theory, it turns out that non-perturbative information is present in a coded form in perturbation theory and it can be decoded. We take advantage of this feature, which is particularly useful to understand some unresolved mysteries of QCD from first principles. In particular, we use: a) Circle compactificationsmore » which provide a semi-classical window to study confinement and mass gap problems, and calculable prototypes of the deconfinement phase transition; b) Resurgence theory and transseries which provide a unified framework for perturbative and non-perturbative expansion; c) Analytic continuation of path integrals and Lefschetz thimbles which may be useful to address sign problem in QCD at finite density.« less

Authors:
ORCiD logo [1]
  1. North Carolina State Univ., Raleigh, NC (United States)
Publication Date:
Research Org.:
North Carolina State Univ., Raleigh, NC (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
OSTI Identifier:
1360218
Report Number(s):
DOE-NCSU-13036
DOE Contract Number:
SC0013036
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

Citation Formats

Unsal, Mithat. New Methods in Non-Perturbative QCD. United States: N. p., 2017. Web. doi:10.2172/1360218.
Unsal, Mithat. New Methods in Non-Perturbative QCD. United States. doi:10.2172/1360218.
Unsal, Mithat. Tue . "New Methods in Non-Perturbative QCD". United States. doi:10.2172/1360218. https://www.osti.gov/servlets/purl/1360218.
@article{osti_1360218,
title = {New Methods in Non-Perturbative QCD},
author = {Unsal, Mithat},
abstractNote = {In this work, we investigate the properties of quantum chromodynamics (QCD), by using newly developing mathematics and physics formalisms. Almost all of the mass in the visible universe emerges from a quantum chromodynamics (QCD), which has a completely negligible microscopic mass content. An intimately related issue in QCD is the quark confinement problem. Answers to non-perturbative questions in QCD remained largely elusive despite much effort over the years. It is also believed that the usual perturbation theory is inadequate to address these kinds of problems. Perturbation theory gives a divergent asymptotic series (even when the theory is properly renormalized), and there are non-perturbative phenomena which never appear at any order in perturbation theory. Recently, a fascinating bridge between perturbation theory and non-perturbative effects has been found: a formalism called resurgence theory in mathematics tells us that perturbative data and non-perturbative data are intimately related. Translating this to the language of quantum field theory, it turns out that non-perturbative information is present in a coded form in perturbation theory and it can be decoded. We take advantage of this feature, which is particularly useful to understand some unresolved mysteries of QCD from first principles. In particular, we use: a) Circle compactifications which provide a semi-classical window to study confinement and mass gap problems, and calculable prototypes of the deconfinement phase transition; b) Resurgence theory and transseries which provide a unified framework for perturbative and non-perturbative expansion; c) Analytic continuation of path integrals and Lefschetz thimbles which may be useful to address sign problem in QCD at finite density.},
doi = {10.2172/1360218},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Jan 31 00:00:00 EST 2017},
month = {Tue Jan 31 00:00:00 EST 2017}
}

Technical Report:

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  • In this talk I will briefly discuss some features of light-front quantization methods for nonperturbative QCD in comparison with traditional lattice methods. Some of the novel features and new directions are illustrated in the transparency file: http://www.slac.stanford.edu/grp/th/lectures/BNLlattice.pdf.
  • New sets of spin observables and relations/sum rules were developed that could be tested in a class of experiments including exclusive deeply virtual electron and neutrino proton/nucleus scattering. Advancements in the phenomenology for the following outstanding problems at the next QCD frontier of nuclear physics were obtained: (1) the origin of the proton spin and its decomposition into quark and gluon spin and orbital angular momentum components; (2) the size of the hadronic matrix elements entering processes at the Intensity Frontier, from neutron and nuclear beta decay, to the experimental extraction of the neutron Electric Dipole Moment; (3) Monitoring themore » transition of quarks and gluons into protons, neutrons and pions to form the atomic nucleus.« less
  • Improved understanding of non-perturbative QCD dynamics can be obtained in terms of soft color exchange models. Their essence is the variation of color string-field topologies giving a unified description of final states in high energy interactions. In particular, both events with and without large rapidity gaps are obtained in agreement with data from ep at HERA and p{anti p} at the Tevatron, where also the surprisingly large production rate of high-p{sub perp} charmonium and bottomonium is reproduced.
  • The FLUKA Monte Carlo code, presently used in cosmic ray physics, contains packages to sample soft hadronic processes which are built according to the Dual Parton Model. This is a phenomenological model capable of reproducing many of the features of hadronic collisions in the non perturbative QCD regime. The basic principles of the model are summarized and, as an example, the associated Lambda-K production is discussed. This is a process which has some relevance for the calculation of atmospheric neutrino fluxes.
  • This report summarizes research in theoretical high energy physics carried out under grant support by Mithat Unsal, Jeff Greensite and Maarten Golterman, together with a list of publications generated under this grant.