Nuclear Theory·nucl-th

Monday·August 21, 2017

9 papers—5 primary·4 cross-listed

06
[Submitted on 17 Aug 2017] (cross-list from hep-ph)
Quantifying finite-momentum effects in meson quasi-PDFs
T. J. Hobbs🇺🇸
The recently proposed large momentum effective theory (LaMET) of Ji has led to a burst of activity among lattice practitioners to perform and control the first pioneering calculations of the quasi-PDFs of the nucleon. These calculations represent approximations to the standard PDFs defined as correlation functions of fields with lightlike separation, being instead correlations along a longitudinal direction of the operator $γ^{z}$ ; as such, they differ from standard PDFs by power-suppressed $1 / p_{z}^{2}$ corrections, becoming exact in the limit $p_{z} \to \infty$ . Investigating the systematics of this behavior thus becomes crucial to understanding the validity of LaMET calculations. While this has been done using models for the nucleon, an analogous dedicated study has not been carried out for the $π$ and $ρ$ quark distribution functions. Using a constituent quark model, a systematic calculation is performed to estimate the size and $x$ dependence of the finite- $p_{z}$ effects in these quasi-PDFs, finding them to be potentially tamer for lighter mesons than for the collinear quasi-PDFs of the nucleon.
Comments:
10 pages, 4 two-panel figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1708.05463 [pdf]
PRD(2018)·38 citations
07
[Submitted on 12 Jul 2017] (cross-list from cond-mat.stat-mech)
Nonequilibrium thermodynamics with binary quantum correlations
Klaus Morawetz
The balance equations for thermodynamic quantities are derived from the nonlocal quantum kinetic equation. The nonlocal collisions lead to molecular contributions to the observables and currents. The corresponding correlated part of the observables is found to be given by the rate to form a molecule multiplied with its lifetime which can be considered as collision duration. Explicit expressions of these molecular contributions are given in terms of the scattering phase shifts. The two-particle form of the entropy is derived. This extends the Landau quasiparticle picture by two-particle molecular contributions. There is a continuous exchange of correlations into kinetic parts condensing into the rate of correlated variables for energy and momentum. For the entropy, an explicit gain remains and Boltzmann's H-theorem is proved including the molecular parts of the entropy.
Comments:
corrected formulae
Subjects:
Statistical Mechanics (cond-mat.stat-mech); Strongly Correlated Electrons (cond-mat.str-el); Nuclear Theory (nucl-th); Plasma Physics (physics.plasm-ph)
arXiv:
1708.05602 [pdf]
PRE(2017)·9 citations
08
[Submitted on 18 Aug 2017] (cross-list from nucl-ex)
Nuclear Structure Functions at a Future Electron-Ion Collider
E. C. Aschenauer (1)🇺🇸 · S. Fazio (1)🇺🇸 · M. A. C. Lamont (1)🇺🇸 · H. Paukkunen (2 and 3)🇫🇮 · Pia Zurita (1) ((1) Brookhaven National Laboratory, (2) University of Jyvaskyla, (3) Helsinki Institute of Physics)🇺🇸
The quantitative knowledge of heavy nuclei's partonic structure is currently limited to rather large values of momentum fraction $x$ -- robust experimental constraints below $x \sim 1 0^{- 2}$ at low resolution scale $Q^{2}$ are particularly scarce. This is in sharp contrast to the free proton's structure which has been probed in deep inelastic scattering (DIS) measurements down to $x \sim 1 0^{- 5}$ at perturbative resolution scales. The construction of an Electron-Ion Collider (EIC) with a possibility to operate with a wide variety of nuclei, will allow one to explore the low- $x$ region in much greater detail. In the present paper we simulate the extraction of the nuclear structure functions from measurements of inclusive and charm reduced cross sections at an EIC. The potential constraints are studied by analyzing simulated data directly in a next-to-leading order global fit of nuclear parton distribution functions based on the recent EPPS16 analysis. A special emphasis is placed on studying the impact an EIC would have on extracting the nuclear gluon PDF, the partonic component most prone to non-linear effects at low $Q^{2}$ . In comparison to the current knowledge, we find that the gluon PDF can be measured at an EIC with significantly reduced uncertainties.
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1708.05654 [pdf]
PRD(2017)·77 citations
09
[Submitted on 18 Aug 2017] (cross-list from hep-th)
Strongly-coupled anisotropic gauge theories and holography
Dimitrios Giataganas🇹🇼 · Umut Gürsoy🇳🇱 · Juan F. Pedraza🇳🇱
We initiate a non-perturbative study of anisotropic, non-conformal and confining gauge theories that are holographically realized in gravity by generic Einstein-Axion-Dilaton systems. In the vacuum our solutions describe RG flows from a conformal field theory in the UV to generic scaling solutions in the IR with generic hyperscaling violation and dynamical exponents $θ$ and $z$ . We formulate a generalization of the holographic c-theorem to the anisotropic case. At finite temperature, we discover that the anisotropic deformation reduces the confinement-deconfinement phase transition temperature suggesting a possible alternative explanation of inverse magnetic catalysis solely based on anisotropy. We also study transport and diffusion properties in anisotropic theories and observe in particular that the butterfly velocity that characterizes both diffusion and growth of chaos transverse to the anisotropic direction, saturates a constant value in the IR which can exceed the bound given by the conformal value.
Comments:
6 pages, 4 figures; v2: minor improvements, references added, version accepted for publication in PRL
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1708.05691 [pdf]
PRL(2018)·143 citations

Affiliations

first authorsco-authorsvia INSPIRE

Quantifying finite-momentum effects in meson quasi-PDFs

Nonequilibrium thermodynamics with binary quantum correlations

Nuclear Structure Functions at a Future Electron-Ion Collider

Strongly-coupled anisotropic gauge theories and holography

Affiliations