Nuclear Theory·nucl-th

Monday·April 16, 2018

14 papers—8 primary·6 cross-listed

09
[Submitted on 12 Apr 2018] (cross-list from hep-th)
Partonic quasidistributions in two-dimensional QCD
Yu Jia🇨🇳 · Shuangran Liang🇨🇳 · Xiaonu Xiong🇩🇪 · Rui Yu🇨🇳
As a sequel of our preceding work [1] we carry out a comprehensive comparative study between the quasi parton distribution functions (PDFs), distribution amplitudes (DAs) and their light-cone counterparts for various flavor-neutral mesons, in the context of the 't Hooft model, that is, the two-dimensional QCD in the large $N$ limit. In contrast to the original derivation via diagrammatic techniques exemplified by Dyson-Schwinger and Bethe-Salpeter equations, here we employ the Hamiltonian operator approach to reconstruct the celebrated 't Hooft equation in light-front quantization, and Bars-Green equations in equal-time quantization. The novelty of our derivation is to employ the soft momentum cutoff as the IR regulator. As a virtue of this operator approach, the functional form of the quasi distributions can be transparently built out of the Bars-Green wave functions and the Bogoliubov angle with the aid of bosonization technique. Equipped with various bound-state wave functions numerically inferred in [1], we then investigate how rapidly the quasi distributions approach their light-cone counterparts with the increasing meson momentum. We observe that, light mesons' quasi distributions approach the light-cone distributions in a slower pace than the heavy quarkonia. Curiously, lattice simulations of quasi distributions in four-dimensional QCD also discover this feature. Furthermore, we also compute the partonic light-cone PDF and quasi-PDF to one-loop order in perturbation theory, again employing the momentum cutoff as the IR regulator. We explicitly verify one of the backbones underlying the large momentum effective field theory (LaMET), namely, both quasi-PDFs and light-cone PDFs in $QCD_{2}$ indeed possess the same IR behavior at leading order in $1/ P^{z}$
Comments:
45 pages, 9 figures, 1 table
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1804.04644 [pdf]
PRD(2018)·44 citations
10
[Submitted on 12 Apr 2018] (cross-list from hep-ph)
First Subleading Power Resummation for Event Shapes
Ian Moult🇺🇸 · Iain W. Stewart🇺🇸 · Gherardo Vita🇺🇸 · Hua Xing Zhu🇨🇳
We derive and analytically solve renormalization group (RG) equations of gauge invariant non-local Wilson line operators which resum logarithms for event shape observables $τ$ at subleading power in the $τ ≪ 1$ expansion. These equations involve a class of universal jet and soft functions arising through operator mixing, which we call $θ$ -jet and $θ$ -soft functions. An illustrative example involving these operators is introduced which captures the generic features of subleading power resummation, allowing us to derive the structure of the RG to all orders in $α_{s}$ , and provide field theory definitions of all ingredients. As a simple application, we use this to obtain an analytic leading logarithmic result for the subleading power resummed thrust spectrum for $H \to g g$ in pure glue QCD. This resummation determines the nature of the double logarithmic series at subleading power, which we find is still governed by the cusp anomalous dimension. We check our result by performing an analytic calculation up to $O (α_{s}^{3})$ . Consistency of the subleading power RG relates subleading power anomalous dimensions, constrains the form of the $θ$ -soft and $θ$ -jet functions, and implies an exponentiation of higher order loop corrections in the subleading power collinear limit. Our results provide a path for carrying out systematic resummation at subleading power for collider observables.
Comments:
39 pages + 2 Appendices, 2 figures. v2: journal version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1804.04665 [pdf]
JHEP(2018)·120 citations
11
[Submitted on 13 Apr 2018] (cross-list from hep-ph)
Analysis of $Λ_{c} (2595)$ , $Λ_{c} (2625)$ , $Λ_{b} (5912)$ , $Λ_{b} (5920)$ based on a chiral partner structure
Yohei Kawakami🇯🇵 · Masayasu Harada🇯🇵
We construct an effective hadronic model including $Λ_{c} (2595)$ , $Λ_{c} (2625)$ , $Λ_{b} (5912)$ and $Λ_{b} (5920)$ regarding them as chiral partners to $Σ_{c} (2455)$ , $Σ_{c} (2520)$ , $Σ_{b}$ and $Σ_{b}^{*}$ , respectively, with respecting the chiral symmetry and heavy-quark spin-flavor symmetry. We determine the model parameters from the experimental data for relevant masses and decay widths of $Σ_{c}^{(*)}$ and $Λ_{c} (2595)$ . Then, we study the decay widths of $Λ_{c} (2625)$ , $Λ_{b} (5912)$ and $Λ_{b} (5920)$ . We find that, although the decay of $Λ_{c} (2595)$ is dominated by the resonant contribution through $Σ_{c} (2455)$ , non-resonant contributions are important for $Λ_{c} (2625)$ , $Λ_{b} (5912)$ and $Λ_{b} (5920)$ , which reflects the chiral partner structure. We also study the radiative decays of the baryons, and show that each of their widths is determined from the radiative decay width of their chiral partners.
Comments:
2 figures, 11 pages
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1804.04872 [pdf]
PRD(2018)·32 citations
12
[Submitted on 10 Apr 2018] (cross-list from astro-ph.HE)
Crust breaking and the limiting rotational frequency of neutron stars
F. J. Fattoyev · C. J. Horowitz · Hao Lu
The limiting rotational frequency of neutron stars may be determined by the strength of their crusts. As a star spins up from accretion, centrifugal forces will cause the crust to fail. If the crust breaks unevenly, a rotating mass quadrupole moment will radiate gravitational waves (GW). This radiation can prevent further spin up and may be a promising source for continuous GW searches. We calculate that for a breaking strain (strength) of neutron star crust that is consistent with molecular dynamics simulations, the crust may fail at rotational frequencies in agreement with observations.
Comments:
5 pages, 4 figures, 2 tables
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
1804.04952 [pdf]
26 citations
13
[Submitted on 13 Apr 2018] (cross-list from hep-ph)
TMD gluon distributions at small x in the CGC theory
Elena Petreska🇳🇱
We review recent progress in the description of unpolarized transverse-momentum-dependent (TMD) gluon distributions at small $x$ in the color glass condensate (CGC) effective theory. We discuss the origin of the non-universality of TMD gluon distributions in the TMD factorization framework and in the CGC theory and the equivalence of the two approaches in their overlapping domain of validity. We show some applications of this equivalence, including recent results on the behavior of TMD gluon distributions at small $x$ , and on the study of gluon saturation. We discuss recent advances in the unification of the TMD evolution and the non-linear small- $x$ evolution of gluon distributions.
Comments:
Invited review article for the International Journal of Modern Physics E (Nuclear Physics). Version accepted for publication. 28 pages, 9 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1804.04981 [pdf]
IJMPE(2018)·47 citations
14
[Submitted on 13 Apr 2018] (cross-list from hep-ph)
Deconfinement Transition Effects on Cosmological Parameters and Primordial Gravitational Wave Spectrum
P. Castorina🇮🇹 · D. Lanteri🇮🇹 · S. Mancani🇮🇹
The cosmological evolution can be described in terms of directly measurable cosmological scalar parameters (deceleration $q$ , jerk $j$ , snap $s$ , etc...) constructed out of high order derivatives of the scale factor. Their behavior at the critical temperature of the Quantum Chromodynamics (QCD) phase transition in early universe could be a specific tool to study the transition, analogously to the fluctuations of conserved charges in QCD. We analyze the effect of the crossover transition from quarks and gluons to hadrons in early universe on the cosmological scalars and on the gravitational wave spectrum, by using the recent lattice QCD equation of state and including the electroweak degrees of freedom and different models of dark matter. Near the transition the cosmological parameters follow the behavior of QCD trace anomaly and of the speed of sound of the entire system. The effects of deconfinement turn out to be more relevant for the modification of the primordial spectrum of gravitational waves and our complete analysis, based on lattice QCD simulations and on the hadron resonance gas below the critical temperature, refines previous results.
Comments:
13 pages,13 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1804.04989 [pdf]
PRD(2018)·7 citations

Affiliations

first authorsco-authorsvia INSPIRE

Partonic quasidistributions in two-dimensional QCD

First Subleading Power Resummation for Event Shapes

Analysis of Λc​(2595), Λc​(2625), Λb​(5912), Λb​(5920) based on a chiral partner structure

Crust breaking and the limiting rotational frequency of neutron stars

TMD gluon distributions at small x in the CGC theory

Deconfinement Transition Effects on Cosmological Parameters and Primordial Gravitational Wave Spectrum

Affiliations

Analysis of $Λ_{c} (2595)$ , $Λ_{c} (2625)$ , $Λ_{b} (5912)$ , $Λ_{b} (5920)$ based on a chiral partner structure