Nuclear Theory·nucl-th

Wednesday·April 20, 2022

11 papers—5 primary·6 cross-listed

06
Constraining the equation of state of neutron stars using multimessenger observations
Bhaskar Biswas🇮🇳
Neutron stars are the densest objects known in our visible universe. Properties of matter inside a neutron star are encoded in its equation of state, which has wide-ranging uncertainty from a theoretical perspective. With the current understanding of quantum chromodynamics, it is hard to determine the interactions of neutron star matter at such high densities. Also performing many body calculations is computationally intractable. Besides the constitution of the neutron star core is highly speculative -- it is not ruled out that it contains exotic matter like strange baryons, meson condensates, quark matter, etc. Although the matter inside the neutron star is extremely dense, but the temperature of this object is very cold in most of its life span. We cannot produce such dense but rather cold material in our laboratory. Since probing the physics of neutron star matter is inaccessible by our earth based experiments, we look for astrophysical observations of neutron stars. This thesis deals with the theoretical and computational techniques required to translate neutron star observables from astrophysical observations to its equation of state.
↳ astro-ph.HEgr-qcnucl-th0 citations
07
Bottomonium-like tetraquarks in a chiral quark model
Gang Yang🇨🇳 · Jialun Ping🇨🇳 · Jorge Segovia🇪🇸
The low-lying bottomonium-like tetraquarks $b b ˉ q q ˉ$ $(q = u, d, s)$ with spin-parity $J^{P} = 0^{+}$ , $1^{+}$ and $2^{+}$ , and isospin $I = 0, 1$ or $\frac{1}{2}$ , are systematically investigated within the theoretical framework of real- and complex-scaling range of a chiral quark model, which has already been successfully applied in analysis of several multiquark systems. A complete four-body $S$ -wave function, which includes meson-meson, diquark-antidiquark and K-type arrangements of quarks, along with all possible color configurations are considered. In the $b b ˉ q q ˉ$ $(q = u, d)$ tetraquark system, we found resonance states of $B^{(*)} B ˉ^{(*)}$ , $Υ ω$ , $Υ ρ$ and $η_{b} ρ$ nature with all possible $I (J^{P})$ quantum numbers. Their masses are generally located in the energy range $11.0 - 11.3$ GeV and their widths are less than $10$ MeV. In addition, extremely narrow resonances, with two-meson strong decay widths less than $1.5$ MeV, are obtained in both $b b ˉ u s ˉ$ and $b b ˉ s s ˉ$ tetraquark systems. Particularly, four radial excitations of $Υ K^{*}$ and $η_{b} K^{*}$ are found at $\sim 11.1$ GeV in $J^{P} = 0^{+}$ , $1^{+}$ and $2^{+}$ channels of $b b ˉ u s ˉ$ system. One $Υ (1 S) ϕ (2 S)$ resonance state is obtained at $11.28$ GeV in the $J^{P} = 1^{+}$ sector.
↳ hep-phhep-exhep-latnucl-ex+1PRD(2022)·8 citations
08
Chiral perturbation theory for heavy hadrons and chiral effective field theory for heavy hadronic molecules
Lu Meng🇩🇪 · Bo Wang🇨🇳 · Guang-Juan Wang🇯🇵 · Shi-Lin Zhu🇨🇳
Chiral symmetry and its spontaneous breaking play an important role both in the light hadron and heavy hadron systems. The chiral perturbation theory ( $χ$ PT) is the low energy effective field theory of the QCD. In this work, we shall review the investigations on the chiral corrections to the properties of the heavy mesons and baryons within the framework of $χ$ PT. We will also review the scatterings of the light pseudoscalar mesons and heavy hadrons, through which many new resonances such as the $D_{s 0}^{*} (2317)$ could be understood. Moreover, many new hadron states were observed experimentally in the past decades. A large group of these states is near-threshold resonances, such as the charged charmoniumlike $Z_{c}$ and $Z_{cs}$ states, bottomoniumlike $Z_{b}$ states, hidden-charm pentaquark $P_{c}$ and $P_{cs}$ states and the doubly charmed $T_{cc}$ state, etc. They are very good candidates of the loosely bound molecular states composed of a pair of charmed (bottom) hadrons, which are very similar to the loosely bound deuteron. The modern nuclear force was built upon the chiral effective field theory ( $χ$ EFT), which is the extension of the $χ$ PT to the systems with two matter fields. The long-range and medium-long-range interactions between two nucleons arise from the single- and double-pion exchange respectively, which are well constrained by the chiral symmetry and its spontaneous breaking. The short-distance interactions can be described by the low energy constants. Such a framework works very well for the nucleon-nucleon scattering and nuclei. In this work, we will perform an extensive review of the progress on the heavy hadronic molecular states within the framework of $χ$ EFT. We shall emphasize that the same chiral dynamics not only govern the nuclei and forms the deuteron, but also dictates the shallow bound states or resonances composed of two heavy hadrons.
↳ hep-phhep-exhep-latnucl-thPhys.Rept.(2023)·347 citations
09
Velocity-like maximum polarization: irreversibility and quantum measurements
Oleg Teryaev🇷🇺
The polarization emerging in the subsequent scattering processes can never exceed $1$ which corresponds to the fully polarized pure state. This property is shown to be provided by the addition rule similar to that for relativistic velocities never exceeding the speed of light. The cases of spin $1/2$ and $1$ are considered. The photon linear polarization in Thomson scattering is monotonically increasing. This directness is shown to be a consequence of spin measurement procedure and may be the particular example of ithe anticipated relation between quantum measurement and time irreversibility. The emergent polarization may be considered as a case of opposing time's arrows corresponding to microscopic (spin) and macroscopic (momentum) degrees of freedom, respectively.
↳ quant-phgr-qchep-phnucl-thPRC(2022)·3 citations
10
Evolution of the $γ$ -ray strength function in neodymium isotopes
M. Guttormsen · K. O. Ay · M. Ozgur · E. Algin · A. C. Larsen · F. L. Bello Garrote · H. C. Berg · L. Crespo Campo · T. Dahl-Jacobsen · F. W. Furmyr · D. Gjestvang · A. Görgen and 15 other authors
The experimental gamma-ray strength functions (gamma-SFs) of 142,144-151Nd have been studied for gamma-ray energies up to the neutron separation energy. The results represent a unique set of gamma-SFs for an isotopic chain with increasing nuclear deformation. The data reveal how the low-energy enhancement, the scissors mode and the pygmy dipole resonance evolve with nuclear deformation and mass number. The data indicate that the mechanisms behind the low-energy enhancement and the scissors mode are decoupled from each other.
↳ nucl-exnucl-thPRC(2022)·27 citations
11
$J / ψ$ near threshold in holographic QCD: A and D gravitational form factors
Kiminad A. Mamo🇺🇸 · Ismail Zahed🇺🇸
The diffractive photoproduction of $J /Ψ$ on a nucleon, is mostly due to gluonic exchanges at all $s$ . In holographic QCD (large number of colors and strong $^{'}$ t Hooft coupling), these exchanges are captured by gravitons near threshold, and their Reggeized Pomeron form asymptotically. We revisit our holographic analysis of the A and D gravitational form factors in light of the new lattice data, and use them to refine our predictions for the photoproduction of $J /Ψ$ near threshold, and the comparison to the GlueX data. We use these results to estimate the scalar and mass radii of the nucleon, and describe the gravitational pressure and shear across a nucleon.
↳ hep-phhep-exhep-thnucl-ex+1PRD(2022)·94 citations

Affiliations

first authorsco-authorsvia INSPIRE

Constraining the equation of state of neutron stars using multimessenger observations

Bottomonium-like tetraquarks in a chiral quark model

Chiral perturbation theory for heavy hadrons and chiral effective field theory for heavy hadronic molecules

Velocity-like maximum polarization: irreversibility and quantum measurements

Evolution of the γ-ray strength function in neodymium isotopes

J/ψ near threshold in holographic QCD: A and D gravitational form factors

Affiliations

Evolution of the $γ$ -ray strength function in neodymium isotopes

$J / ψ$ near threshold in holographic QCD: A and D gravitational form factors