Nuclear Theory·nucl-th

Wednesday·September 27, 2023

12 papers—7 primary·5 cross-listed

08
Near-threshold hadron scattering with effective field theory
Katsuyoshi Sone🇯🇵 · Tetsuo Hyodo🇯🇵
When an exotic hadron locates near the threshold with the channel couplings, the internal structure of the exotic hadron is related to the scattering length. To incorporate the threshold effect, the Flatté amplitude has been often used to determine the scattering length. It is however known that an additional constraint is imposed on the Flatte amplitude near the threshold. We discuss this problem by using the effective field theory for the coupled-channel scattering.
↳ hep-phnucl-thEPJ Web Conf.(2024)·1 citation
09
Threshold-cusp explanation for $X$ and $Z_{cs}$ in $B^{+} \to J / ψ ϕ K^{+}$
S.X. Nakamura (Shandong Univ.)🇨🇳 · X. Luo (Anhui Univ.)🇨🇳
Several $X$ and $Z_{cs}$ exotic hadrons were claimed in the LHCb's amplitude analysis on $B^{+} \to J / ψ ϕ K^{+}$ . The data shows that all the peaks and also dips in the spectra are located at thresholds of seemingly relevant meson-meson channels. While the LHCb analysis fitted the peaks with Breit-Wigner resonances, threshold kinematical cusps might be the cause of such structures. We thus analyze the LHCb data considering the threshold cusps. Our model is simultaneously fitted to $J / ψ ϕ$ , $J / ψ K^{+}$ , and $K^{+} ϕ$ invariant mass distributions. The threshold cusps fit well all the $X$ , $Z_{cs}$ , and dip structures. Our analysis indicates that spin-parity of the $X (4274)$ and $X (4500)$ structures are $0^{-}$ and $1^{-}$ , respectively. This is different from the LHCb's spin-parity assignments ( $1^{+}$ and $0^{+}$ ). The number of fitting parameters can be significantly reduced by considering the relevant threshold cusps. Our analysis shows that $D_{s}^{(*)} D ˉ^{*}$ scattering lengths are consistent with zero. This disfavors an explanation of $Z_{cs} (4000)$ and $Z_{cs} (4220)$ as $D_{s}^{(*)} D ˉ^{*}$ molecules, which is consistent with lattice QCD via the SU(3) relation.
↳ hep-phhep-exnucl-thNuovo Cim.C(2024)·2 citations
10
Relativistic hydrodynamics with phase transition
F. Taghinavaz🇮🇷
Assessing the applicability of hydrodynamic expansions close to phase transition points is crucial from either theoretical or phenomenological points of view. We explore this within the gauge/gravity duality, using the Einstein-Klein-Gordon model, a bottom-up string theory construction. This model incorporates a parameter, $B_{4}$ , that simulates different types of phase transitions in the strongly coupled field theory existing at the boundary. We thoroughly examine the thermodynamics and dynamics of time-dependent, linearized perturbations in the spin-2, spin-1, and spin-0 sectors. Our findings suggest that "hydrodynamic series breakdown near transition points" is valid exclusively for second-order phase transitions, not for crossovers or first-order phase transitions. Additionally, we observe that the high-temperature and low-temperature limits of the radius of convergence for the hydrodynamic series ( $q_{c}^{2}$ ) are equal. We also discover that the relationship $(Max ∣ q_{c}^{2} ∣)_{spin-2} < (Max ∣ q_{c}^{2} ∣)_{spin-0} < (Max ∣ q_{c}^{2} ∣)_{spin-1}$ is consistent for different spin sectors, regardless of the phase transition type. At the chaos point, we observe the emergence of pole-skipping behavior for both gravity and scalar perturbations at $ω_{n} = - 2 π T ni$ . Lastly, comparing the chaos momentum with $q_{c}^{2}$ , we find that $q_{p s}^{2} < q_{c}^{2}$ , except for extremely high temperatures.
↳ hep-thhep-phnucl-thEPJC(2024)·3 citations
11
Hyperonic uncertainties in neutron stars, mergers and supernovae
Hristijan Kochankovski · Angels Ramos · Laura Tolos
In this work we delve into the temperature-dependent Equation of State (EoS) of baryonic matter within the framework of the FSU2H $^{*}$ hadronic model, which comprehensively incorporates hyperons and is suitable for relativistic simulations of neutron star mergers and supernovae. To assess the impact of the uncertainties in the hyperonic sector on astrophysical observables, we introduce two additional models, namely FSU2H $^{*}$ L and FSU2H $^{*}$ U. These models cover the entire spectrum of variability of hyperonic potentials, as derived from experimental data. Our investigations reveal that these uncertainties extend their influence not only to the relative abundances of various particle species but also to the EoS itself and, consequently, have an impact on the global properties of both cold and hot neutron stars. Notably, their effects become more pronounced at large temperatures, owing to the increased presence of hyperons. These findings have direct implications for the outcomes of relativistic simulations of neutron star mergers and supernovae, emphasizing the need of accounting for hyperonic uncertainties to ensure the accuracy and reliability of such simulations in astrophysical contexts.
↳ astro-ph.HEnucl-thMNRAS(2024)·13 citations
12
Coupled oscillator model of a trapped Fermi gas at the BEC-BCS crossover
Sergueï V. Andreev
We address theoretically the puzzling discontinuity of the radial quadrupole mode frequency observed in a trapped Fermi gas across the BEC-BCS crossover. We apply the scaling transformation to a two-channel model of a resonant Fermi superfluid and argue that the frequency downshift in the crossover region is due to Feshbach coupling of the molecular Bose-Einstein condensate (BEC) to the surrounding Fermi sea. The Bose and Fermi components of the gas act as coupled macroscopic oscillators. The frequency jump corresponds to the point where the closed-channel molecules are entirely converted into the Fermi sea. This implies linear scaling of the "critical" detuning between the scattering channels with the Fermi energy, which can be readily verified in an experiment.
↳ cond-mat.quant-gascond-mat.mes-hallcond-mat.str-elcond-mat.supr-con+1Physica A(2025)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE

Near-threshold hadron scattering with effective field theory

Threshold-cusp explanation for X and Zcs​ in B+→J/ψϕK+

Relativistic hydrodynamics with phase transition

Hyperonic uncertainties in neutron stars, mergers and supernovae

Coupled oscillator model of a trapped Fermi gas at the BEC-BCS crossover

Affiliations

Threshold-cusp explanation for $X$ and $Z_{cs}$ in $B^{+} \to J / ψ ϕ K^{+}$