Nuclear Theory·nucl-th

Thursday·November 21, 2019

13 papers—8 primary·5 cross-listed

09
[Submitted on 19 Nov 2019] (cross-list from hep-th)
New Flavor-Kinematics Dualities and Extensions of Nonlinear Sigma Models
Ian Low🇺🇸 · Zhewei Yin🇺🇸
Nonlinear sigma model (NLSM) based on the coset $SU (N) \times SU (N) / SU (N)$ exhibits several intriguing features at the leading $O (p^{2})$ in the derivative expansion, such as the flavor-kinematics duality and an extended theory controlling the single and triple soft limits. In both cases the cubic biadjoint scalar theory plays a prominent role. We extend these features in two directions. First we uncover a new extended theory for $SO (N + 1) / SO (N)$ NLSM at $O (p^{2})$ , which is a cubic bifundamental/biadjoint scalar theory. Next we provide evidence for flavor-kinematics dualities up to $O (p^{4})$ for both $SU (N)$ and $SO (N)$ NLSM's. In particular, we introduce a new duality building block based on the symmetric tensor $δ^{ab}$ and demonstrate several flavor-kinematics dualities for 4-point amplitudes, which precisely match the soft blocks employed to soft-bootstrap the NLSM's up to $O (p^{4})$ .
Comments:
5 pages, 1 figure; matched to the published version in v2
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1911.08490 [pdf]
PLB(2020)·37 citations
10
[Submitted on 20 Nov 2019] (cross-list from hep-ph)
Refined analysis on the parton distribution functions of the proton
X. G. Wang🇦🇺 · A. W. Thomas🇦🇺
We explore the application of a two-component model of proton structure functions in the analysis of deep-inelastic scattering (DIS) data at low $Q^{2}$ and small $x$ . This model incorporates both vector meson dominance and the correct photo-production limit. The CJ15 parameterization is applied to the QCD component, in order to take into account effects of order $1/ Q^{2}$ effects, such as target mass corrections and higher twist contributions. The parameters of the leading twist parton distribution functions and higher twist coefficient functions are determined by fitting deep inelastic scattering data. The second moments of the parton distribution functions are extracted and compared with other global fits and lattice determinations.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1911.08695 [pdf]
J.Phys.G(2020)·4 citations
11
[Submitted on 20 Nov 2019] (cross-list from hep-ph)
The $ϕ$ meson with finite momentum in a dense medium
HyungJoo Kim🇰🇷 · Philipp Gubler🇯🇵
The dispersion relation of the $ϕ$ meson in nuclear matter is studied in a QCD sum rule approach. In a dense medium, longitudinal and transverse modes of vector particles can have independently modified dispersion relations due to broken Lorentz invariance. Employing the full set of independent operators and corresponding Wilson coefficients up to operator dimension 6, the $ϕ$ meson QCD sum rules are analyzed with changing densities and momenta. The non-trivial momentum dependence of the $ϕ$ meson mass is found to have opposite signs for the longitudinal and transverse modes. Specifically, the mass is reduced by 5 MeV for the longitudinal mode, while its increase amounts to 7 Mev for the transverse mode, both at a momentum scale of 1 GeV. In an experiment which does not distinguish between longitudinal and transverse polarizations, this could in principle be seen as two separated peaks at large momenta. Taking however broadening effects into account, the momentum dependence will most likely be seen as a small but positive effective mass shift and an increased effective width for non-zero momenta.
Comments:
8 pages, 4 figures; version accepted for publication on PLB
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1911.08737 [pdf]
PLB(2020)·44 citations
12
[Submitted on 20 Nov 2019] (cross-list from nucl-ex)
Measurement and microscopic description of odd-even staggering of charge radii of exotic copper isotopes
R. P. de Groote🇧🇪 · J. Billowes🇬🇧 · C. L. Binnersley🇬🇧 · M. L. Bissell🇬🇧 · T. E. Cocolios🇧🇪 · T. Day Goodacre🇨🇭 · G. J. Farooq-Smith · D. V. Fedorov🇷🇺 · K. T. Flanagan🇬🇧 · S. Franchoo🇫🇷 · R. F. Garcia Ruiz🇬🇧 · W. Gins🇧🇪 and 14 other authors
The mesoscopic nature of the atomic nucleus gives rise to a wide array of macroscopic and microscopic phenomena. The size of the nucleus is a window into this duality: while the charge radii globally scale as $A^{1/3}$ , their evolution across isotopic chains reveals unanticipated structural phenomena [1-3]. The most ubiquitous of these is perhaps the Odd-Even Staggering (OES) [4]: isotopes with an odd number of neutrons are usually smaller in size than the trend of their even-neutron neighbours suggests. This OES effect varies with the number of protons and neutrons and poses a significant challenge for nuclear theory [5-7]. Here, we examine this problem with new measurements of the charge radii of short-lived copper isotopes up to the very exotic $^{78}$ Cu $(Z = 29, N = 49)$ , produced at only 20 ions/s, using the highly-sensitive Collinear Resonance Ionisation Spectroscopy (CRIS) method at ISOLDE-CERN. Due to the presence of a single proton outside of the closed Z=28 shell, these measurements provide crucial insights into the single-particle proton structure and how this affects the charge radii. We observe an unexpected reduction in the OES for isotopes approaching the $N = 50$ shell gap. To describe the data, we applied models based on nuclear Density Functional Theory [2,8] (DFT) and ab-initio Valence-Space In-Medium Similarity Renormalization Group (VS-IMSRG) theory [9,10]. Through these comparisons, we demonstrate a relation between the global behavior of charge radii and the saturation density of nuclear matter, and show that the local charge radii variations, which reflect the many-body polarization effects due to the odd neutron, naturally emerge from the VS-IMSRG calculations.
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1911.08765 [pdf]
Nat.Phys.(2020)·131 citations
13
[Submitted on 20 Nov 2019] (cross-list from hep-lat)
Three pion spectrum in the $I = 3$ channel from lattice QCD
Chris Culver🇺🇸 · Maxim Mai🇺🇸 · Ruairí Brett🇺🇸 · Andrei Alexandru🇺🇸 · Michael Döring🇺🇸
Three-body states are critical to the dynamics of many hadronic resonances. We show that lattice QCD calculations have reached a stage where these states can be accurately resolved. We perform a calculation over a wide range of parameters and find all states below inelastic threshold agree with predictions from a state-of-the-art phenomenological formalism. This also illustrates the reliability of the formalism used to connect lattice QCD results to infinite volume physics. Our calculation is performed using three positively charged pions, with different lattice geometries and quark masses.
Subjects:
High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1911.09047 [pdf]
PRD(2020)·106 citations

Affiliations

first authorsco-authorsvia INSPIRE

New Flavor-Kinematics Dualities and Extensions of Nonlinear Sigma Models

Refined analysis on the parton distribution functions of the proton

The ϕ meson with finite momentum in a dense medium

Measurement and microscopic description of odd-even staggering of charge radii of exotic copper isotopes

Three pion spectrum in the I=3 channel from lattice QCD

Affiliations

The $ϕ$ meson with finite momentum in a dense medium

Three pion spectrum in the $I = 3$ channel from lattice QCD