Nuclear Theory·nucl-th

Monday·August 3, 2020

10 papers—4 primary·6 cross-listed

01
Possible molecular states from the $N Δ$ interaction
Zhi-Tao Lu🇨🇳 · Han-Yu Jiang🇨🇳 · Jun He🇨🇳
Recently, a hint for dibaryon $N Δ (D_{21})$ was observed at WASA-AT-COSY with a mass about $30 \pm 10$ MeV below the $N Δ$ threshold. It has a relatively small binding energy compared with the $d^{*} (2380)$ and a width close to the width of the $Δ$ baryon, which suggests that it may be a dibaryon in a molecular state picture. In this work, we study the possible $S$ -wave molecular states from the $N Δ$ interaction within the quasipotential Bethe-Salpeter equation approach. The interaction is described by exchanging $π$ , $ρ$ , and $ω$ mesons. With reasonable parameters, a $D_{21}$ bound state can be produced from the interaction. The results also suggest that there may exist two more possible $D_{12}$ and $D_{22}$ states with smaller binding energies. The $π$ exchange is found to play the most important role to bind two baryons to form the molecular states. An experimental search for possible $N Δ (D_{12})$ and $N Δ (D_{22})$ states will be helpful for understanding the hint of the dibaryon $N Δ (D_{21})$ .
nucl-thhep-phPRC(2020)·15 citations
02
Low mass strange stars and the compact star 1E1207.4-5209 in the Field Correlator Method
F. I. M Pereira🇧🇷
We investigate the possible existence of anomalous mass defects in the low mass region of stellar sequences of strange stars. We employ the nonperturbative equation of state derived in the framework of the Field Correlator Method to describe the hydrostatic equilibrium of the strange matter. The large distance static $Q Q ˉ$ potential $V_{1}$ and the gluon condensate $G_{2}$ are the main parameters of the model. We use the surface gravitational redshift measurements as a probe to determine the ratio $(P / E)_{C}$ at the center of strange stars. For $V_{1} = 0$ and $G_{2} \gappr 0.035 GeV^{4}$ \,, we show that $(P / E)_{C} ≃ 0.262$ and the corresponding redshift $z_{S} ≃ 0.47$ are limiting values, at the maximum mass of the highest mass stellar sequence. As a direct application of our study, we try to determine the values of $V_{1}$ and $G_{2}$ from astrophysical observations of the compact star 1E\,1207.4-5209. Due to the uncertainties in the surface redshift determination, we made two attempts to obtain the model parameters. Our findings show that $(P / E)_{C} = 0.07 3_{+ 0.024}^{+ 0.029}$ \, at 68\% confidence, $V_{1} = 0.44 \pm 0.10$ \,GeV at 90\% confidence and $G_{2} = 0.008 \pm 0.001 GeV^{4}$ at 95\% confidence \, in the first attempt; and $(P / E)_{C} = 0.07 3_{+ 0.024}^{+ 0.029} = 0.087 \pm 0.028$ \, at 71\% confidence, $V_{1} = 0.43 \pm 0.085$ \,GeV at 94\% confidence and $G_{2} = 0.0093 \pm 0.00092 GeV^{4}$ at 94\% confidence in the second attempt. These values of $V_{1}$ and $G_{2}$ are in reasonable agreement with the lattice and QCD sum rules calculations. As a consequence of the high values of $V_{1}$ and $G_{2}$ , the anomalous mass defects of 1E\,1207.4-5209 are $∣ Δ_{2} M ∣ ≃ 2.56 \times 1 0^{53}$ \,erg\, in the first attempt and $∣ Δ_{2} M ∣ ≃ 2.94 \times 1 0^{53}$ \,erg\, in the second attempt.
nucl-thastro-ph.SRhep-lathep-phPRD(2021)·0 citations
03
Linear stability of Israel-Stewart theory in the presence of net-charge diffusion
C. V. Brito🇧🇷 · G. S. Denicol🇧🇷
In this paper, we perform a linear stability analysis of Israel-Stewart theory around a global equilibrium state, including the effects of shear-stress tensor, net-baryon diffusion current and diffusion-viscous coupling. We find all the relevant modes of this theory and derive necessary conditions that these modes must satisfy in order to be stable and subluminal. With these conditions, we then derive constraints for the shear and diffusion relaxation times and the transport coefficients related to diffusion-viscous coupling.
nucl-thhep-thPRD(2020)·46 citations
04
Evidence for the general dominance of proton shells in low-energy fission
K. Mahata🇮🇳 · C. Schmitt🇫🇷 · Shilpi Gupta🇮🇳 · A. Shrivastava🇮🇳 · G. Scamps🇧🇪 · K.-H. Schmidt
A regular pattern, revealing the leading role of the light-fragment nuclear charge, is found to emerge from a consistent analysis of the experimental information collected recently on low-energy asymmetric fission of neutron-deficient nuclei around lead. The observation is corroborated by a theoretical investigation within a microscopic framework, suggesting the importance of proton configurations driven by quadrupole-octupole correlations. This is in contrast to the earlier theoretical interpretations in terms of dominant neutron shells. The survey of a wider area of the nuclear chart by a semi-empirical approach points to the lack of understanding of the competition between the different underlying macroscopic and microscopic forces in a quantitative manner. Combined with previously identified stabilizing forces, the present finding shows a striking connection between the "old" (actinide) and "new" (pre-actinide) islands of asymmetric fission which could steer the strive for an unified theory of fission.
nucl-thnucl-exPLB(2022)·56 citations
05
Higgs-confinement phase transitions with fundamental representation matter
Aleksey Cherman🇺🇸 · Theodore Jacobson🇺🇸 · Srimoyee Sen🇺🇸 · Laurence G. Yaffe🇺🇸
We discuss the conditions under which Higgs and confining regimes in gauge theories with fundamental representation matter fields can be sharply distinguished. It is widely believed that these regimes are smoothly connected unless they are distinguished by the realization of global symmetries. However, we show that when a $U (1)$ global symmetry is spontaneously broken in \emph{both} the confining and Higgs regimes, the two phases can be separated by a phase boundary. The phase transition between the two regimes may be detected by a novel topological vortex order parameter. We first illustrate these ideas by explicit calculations in gauge theories in three spacetime dimensions. Then we show how our analysis generalizes to four dimensions, where it implies that nuclear matter and quark matter are sharply distinct phases of QCD with an approximate $S U (3)$ flavor symmetry.
↳ hep-thhep-phnucl-thPRD(2020)·38 citations
06
Three identical bosons: Properties in non-integer dimensions and in external fields
E. Garrido · A.S. Jensen
Three-body systems that are continuously squeezed from a three-dimensional (3D) space into a two-dimensional (2D) space are investigated. Such a squeezing can be obtained by means of an external confining potential acting along a single axis. However, this procedure can be numerically demanding, or even undoable, especially for large squeezed scenarios. An alternative is provided by use of the dimension $d$ as a parameter that changes continuously within the range $2 \leq d \leq 3$ . The simplicity of the $d$ -calculations is exploited to investigate the evolution of three-body states after progressive confinement. The case of three identical spinless bosons with relative $s$ -waves in 3D, and a harmonic oscillator squeezing potential is considered. We compare results from the two methods and provide a translation between them, relating dimension, squeezing length, and wave functions from both methods. All calculations are then possible entirely within the simpler $d$ -method, but simultaneously providing the equivalent geometry with the external potential.
↳ cond-mat.quant-gasnucl-thphysics.atm-clusquant-phPRResearch(2020)·10 citations
07
Counting Nambu-Goldstone modes of higher-form global symmetries
Yoshimasa Hidaka🇯🇵 · Yuji Hirono🇰🇷 · Ryo Yokokura🇯🇵
We discuss the counting of Nambu-Goldstone (NG) modes associated with the spontaneous breaking of higher-form global symmetries. Effective field theories of NG modes are developed based on symmetry breaking patterns, using a generalized coset construction for higher-form symmetries. We derive a formula of the number of gapless NG modes, which involves expectation values of the commutators of conserved charges, possibly of different degrees.
↳ hep-thcond-mat.str-elhep-phnucl-thPRL(2021)·37 citations
08
Nucleon Gluon Distribution Function from 2+1+1-Flavor Lattice QCD
Zhouyou Fan🇺🇸 · Rui Zhang🇺🇸 · Huey-Wen Lin🇺🇸
The parton distribution functions (PDFs) provide process-independent information about the quarks and gluons inside hadrons. Although the gluon PDF can be obtained from a global fit to experimental data, it is not constrained well in the large- $x$ region. Theoretical gluon-PDF studies are much fewer than those of the quark PDFs. In this work, we present the first lattice-QCD results that access the $x$ -dependence of the gluon unpolarized PDF of the nucleon. The lattice calculation is carried out with nucleon momenta up to 2.16 GeV, lattice spacing $a \approx 0.12$ fm, with valence pion masses of 310 and 690 MeV. We use reduced Ioffe-time distributions to cancel the renormalization and implement a one-loop perturbative pseudo-PDF matching to the lightcone distribution. Our matrix element results in coordinate space are consistent with those obtained from the global PDF fits of CT18 NNLO and NNPDF3.1 NNLO. Our fitted gluon PDF extrapolated to the physical pion mass gives consistent results in the $x > 0.3$ region.
↳ hep-lathep-phnucl-thInt.J.Mod.Phys.A(2021)·73 citations
09
Alternative derivation of the relativistic three-particle quantization condition
Tyler D. Blanton🇺🇸 · Stephen R. Sharpe🇺🇸
We present a simplified derivation of the relativistic three-particle quantization condition for identical, spinless particles described by a generic relativistic field theory satisfying a $Z_{2}$ symmetry. The simplification is afforded by using a three-particle quasilocal K matrix that is not fully symmetrized, $K_{df, 3}^{(u, u)}$ , and makes extensive use of time-ordered perturbation theory (TOPT). We obtain a new form of the quantization condition. This new form can then be related algebraically to the standard quantization condition, which depends on a fully symmetric three-particle K matrix, $K_{df, 3}$ . The new derivation is fully explicit, allowing, for example, a closed-form expression for $K_{df, 3}$ to be given in terms of TOPT amplitudes. The new form of the quantization condition is similar in structure to that obtained in the "finite-volume unitarity" approach, and in a companion paper we make this connection concrete. Our simplified approach should also allow a more straightforward generalization of the quantization condition to nondegenerate particles, and perhaps also to more than three particles.
↳ hep-lathep-phnucl-thPRD(2020)·78 citations
10
Equivalence of relativistic three-particle quantization conditions
Tyler D. Blanton🇺🇸 · Stephen R. Sharpe🇺🇸
We show that a recently derived alternative form of the relativistic three-particle quantization condition for identical particles can be rewritten in terms of the R matrix introduced to give a unitary representation of the infinite-volume three-particle scattering amplitude. Combined with earlier work, this shows the equivalence of the relativistic effective field theory approach of Hansen and Sharpe (Refs.[1,2]) and the "finite-volume unitarity" approach of Mai and Döring (Refs.[3,4]). It also provides a generalization of the latter approach to arbitrary angular momenta of two-particle subsystems.
↳ hep-lathep-phnucl-thPRD(2020)·76 citations

Affiliations

first authorsco-authorsvia INSPIRE