Nuclear Theory·nucl-th

Tuesday·March 2, 2021

17 papers—10 primary·7 cross-listed

11
Recent progresses on QCD phases in a strong magnetic field -- views from Nambu--Jona-Lasinio model
Gaoqing Cao🇨🇳
In this review, we summarize recent progress on the possible phases of quantum chromodynamics (QCD) in the presence of a strong magnetic field, mainly from the views of the chiral effective Nambu--Jona-Lasinio model. Four kinds of phase transitions are explored in detail: chiral symmetry breaking and restoration, neutral pseudoscalar superfluidity, charged pion superfluidity and charged rho superconductivity. In particular, we revisit the unsolved problems of inverse magnetic catalysis effect and competition between the chiral density wave and solitonic modulation phases. It is shown that useful results can be obtained by adopting self-consistent schemes.
↳ hep-phnucl-thEPJA(2021)·59 citations
12
Multi-particle systems on the lattice and chiral extrapolations: a brief review
Maxim Mai🇺🇸 · Michael Döring🇺🇸 · Akaki Rusetsky🇩🇪
The extraction of two- and three-body hadronic scattering amplitudes and the properties of the low-lying hadronic resonances from the finite-volume energy levels in lattice QCD represents a rapidly developing field of research. The use of various modifications of the Lüscher finite-volume method has opened a path to calculate infinite-volume scattering amplitudes on the lattice. Many new results have been obtained recently for different two- and three-body scattering processes, including the extraction of resonance poles and their properties from lattice data. Such studies, however, require robust parametrizations of the infinite-volume scattering amplitudes, which rely on basic properties of $S$ -matrix theory and -- preferably -- encompass systems with quark masses at and away from the physical point. Parametrizations of this kind, provided by unitarized Chiral Perturbation Theory, are discussed in this review. Special attention is paid to three-body systems on the lattice, owing to the rapidly growing interest in the field. Here, we briefly survey the formalism, chiral extrapolation, as well as finite-volume analyses of lattice data.
↳ hep-lathep-phnucl-thEur.Phys.J.ST(2021)·92 citations
13
Rosenbluth separation of $d σ_{L} / dt$ and $d σ_{T} / dt$ in $π^{0}$ deeply virtual electroproduction from the proton
I. Korover🇺🇸 · R.G. Milner🇺🇸
We report on a Rosenbluth separation using previously published data by the CLAS collaboration in Hall B, Jefferson Lab for exclusive $π^{0}$ deeply virtual electroproduction (DVEP) from the proton at a mean $Q^{2}$ of $\approx$ 2 (GeV/c) $^{2}$ . The central question we address is the applicability of factorization in $π^{0}$ DVEP at these kinematics. The results of our Rosenbluth separation clearly demonstrate the dominance of the longitudinal contribution to the cross section. The extracted longitudinal and transverse contributions are in agreement with previous data from Hall A at Jefferson Lab, but over a much wider $- t$ range (0.12 - 1.8 (GeV/c) $^{2}$ ). The measured dominance of the longitudinal contribution at $Q^{2} \approx$ 2 (GeV/c) $^{2}$ is consistent with the expectation of the handbag factorization theorem. We find that $σ_{L} (t) \sim 1/ (- t)$ for $- t >$ 0.5 (GeV/c) $^{2}$ . Determination of both longitudinal and transverse contributions to the deeply virtual $π^{0}$ electroproduction cross section allows extraction of additional GPDs.
↳ hep-phnucl-exnucl-th2 citations
14
High-precision determination of the $K_{e 3}$ radiative corrections
Chien-Yeah Seng🇩🇪 · Daniel Galviz🇩🇪 · Mikhail Gorchtein🇩🇪 · Ulf-G. Meißner🇩🇪
We report a high-precision calculation of the Standard Model electroweak radiative corrections in the $K \to π e^{+} ν (γ)$ decay as a part of the combined theory effort to understand the existing anomaly in the determinations of $V_{u s}$ . Our new analysis features a chiral resummation of the large infrared-singular terms in the radiative corrections and a well-under-control strong interaction uncertainty based on the most recent lattice QCD inputs. While being consistent with the current state-of-the-art results obtained from chiral perturbation theory, we reduce the existing theory uncertainty from $1 0^{- 3}$ to $1 0^{- 4}$ . Our result suggests that the Standard Model electroweak effects cannot account for the $V_{u s}$ anomaly.
↳ hep-phhep-exhep-latnucl-ex+1PLB(2021)·35 citations
15
Weakly bound $H$ dibaryon from SU(3)-flavor-symmetric QCD
Jeremy R. Green🇨🇭 · Andrew D. Hanlon🇩🇪 · Parikshit M. Junnarkar🇩🇪 · Hartmut Wittig🇩🇪
We present the first study of baryon-baryon interactions in the continuum limit of lattice QCD, finding unexpectedly large lattice artifacts. Specifically, we determine the binding energy of the $H$ dibaryon at a single quark-mass point. The calculation is performed at six values of the lattice spacing $a$ , using O( $a$ )-improved Wilson fermions at the SU(3)-symmetric point with $m_{π} = m_{K} \approx 420$ MeV. Energy levels are extracted by applying a variational method to correlation matrices of bilocal two-baryon interpolating operators computed using the distillation technique. Our analysis employs Lüscher's finite-volume quantization condition to determine the scattering phase shifts from the spectrum and vice versa, both above and below the two-baryon threshold. We perform global fits to the lattice spectra using parametrizations of the phase shift, supplemented by terms describing discretization effects, then extrapolate the lattice spacing to zero. The phase shift and the binding energy determined from it are found to be strongly affected by lattice artifacts. Our estimate of the binding energy in the continuum limit of three-flavor QCD is $B_{H}^{SU(3)_{f}} = 4.56 \pm 1.1 3_{stat} \pm 0.6 3_{syst}$ MeV.
↳ hep-lathep-phnucl-thPRL(2021)·139 citations
16
Transition distribution amplitudes and hard exclusive reactions with baryon number transfer
B. Pire🇫🇷 · K. Semenov-Tian-Shansky🇷🇺 · L. Szymanowski🇵🇱
Baryon-to-meson and baryon-to-photon transition distribution amplitudes (TDAs) arise in the collinear factorized description of a class of hard exclusive reactions characterized by the exchange of a non-zero baryon number in the cross channel. These TDAs extend the concepts of generalized parton distributions (GPDs) and baryon distribution amplitudes (DAs). In this review, we discuss the general properties and physical interpretation of baryon-to-meson and baryon-to-photon TDAs. We argue that these non-perturbative objects are a convenient complementary tool to explore the structure of baryons at the partonic level. We present an overview of hard exclusive reactions admitting a description in terms of TDAs. We discuss the first signals from hard exclusive backward meson electroproduction at JLab with the 6 GeV electron beam and explore further experimental opportunities to access TDAs at JLab@12 GeV, PANDA, J-PARC and EIC.
↳ hep-phhep-exnucl-thPhys.Rept.(2021)·37 citations
17
Emergent Hadrons and Diquarks
Kenji Fukushima🇯🇵 · Jan M. Pawlowski🇩🇪 · Nils Strodthoff🇩🇪
We discuss the emergence of a low-energy effective theory with quarks, mesons, diquarks and baryons at vanishing and finite baryon density from first principle QCD. The present work also includes an overview on diquarks at vanishing and finite density, and elucidates the physics of transitional changes from baryonic matter to quark matter including diquarks. This set-up is discussed within the functional renormalisation group approach with dynamical hadronisation. In this framework it is detailed how mesons, diquarks, and baryons emerge dynamically from the renormalisation flow of the QCD effective action. Moreover, the fundamental degrees of freedom of QCD, quarks and gluons, decouple from the dynamics of QCD below the respective mass gaps. The resulting global picture unifies the different low energy effective theories used for low and high densities within QCD, and allows for a determination of the respective low energy constants directly from QCD.
↳ hep-phhep-thnucl-thAnnals Phys.(2022)·42 citations

Affiliations

first authorsco-authorsvia INSPIRE

Recent progresses on QCD phases in a strong magnetic field -- views from Nambu--Jona-Lasinio model

Multi-particle systems on the lattice and chiral extrapolations: a brief review

Rosenbluth separation of dσL​/dt and dσT​/dt in π0 deeply virtual electroproduction from the proton

High-precision determination of the Ke3​ radiative corrections

Weakly bound H dibaryon from SU(3)-flavor-symmetric QCD

Transition distribution amplitudes and hard exclusive reactions with baryon number transfer

Emergent Hadrons and Diquarks

Affiliations

Rosenbluth separation of $d σ_{L} / dt$ and $d σ_{T} / dt$ in $π^{0}$ deeply virtual electroproduction from the proton

High-precision determination of the $K_{e 3}$ radiative corrections

Weakly bound $H$ dibaryon from SU(3)-flavor-symmetric QCD