Analysis of Pcs(4338) and related pentaquark molecular states via QCD sum rules

In this study, we tentatively identify \begin{document}$ P_{cs}(4338) $\end{document} as the \begin{document}$ \bar{D}\Xi_c $\end{document}molecular state and distinguish the isospins of current operators to explore in detail the\begin{document}$ \bar{D}\Xi_c $\end{document}, \begin{document}$ \bar{D}\Lambda_c $\end{document}, \begin{document}$ \bar{D}_s\Xi_c $\end{document}, \begin{document}$ \bar{D}_s\Lambda_c $\end{document}, \begin{document}$ \bar{D}^*\Xi_c $\end{document}, \begin{document}$ \bar{D}^*\Lambda_c $\end{document}, \begin{document}$ \bar{D}^*_s\Xi_c $\end{document}, and \begin{document}$ \bar{D}^*_s\Lambda_c $\end{document} molecular states without strange, with strange, and with double strange in the framework of QCD sum rules. The present exploration favors identifying \begin{document}$ P_{cs}(4338) $\end{document} (\begin{document}$ P_{cs}(4459) $\end{document}) as the \begin{document}$ \bar{D}\Xi_c $\end{document} (\begin{document}$ \bar{D}^*\Xi_c $\end{document}) molecular state with the spin-parity \begin{document}$ J^P={\dfrac{1}{2}}^- $\end{document} (\begin{document}$ {\dfrac{3}{2}}^- $\end{document}) and isospin \begin{document}$ (I,I_3)=(0,0) $\end{document}, and the observation of their cousins with the isospin \begin{document}$ (I,I_3)=(1,0) $\end{document} in the \begin{document}$ J/\psi\Sigma^0/\eta_c\Sigma^0 $\end{document} invariant mass distributions would decipher their inner structures.     

Z0 boson associated b-jet production in high-energy nuclear collisions

The production of vector boson tagged heavy quark jets potentially provides new tools to probe the jet quenching effect. In this paper, we present the first theoretical study on the angular correlations (\begin{document}$ \Delta\phi_{bZ} $\end{document}), transverse momentum imbalance (\begin{document}$ x_{bZ} $\end{document}), and nuclear modification factor (\begin{document}$ I_{AA} $\end{document}) of \begin{document}$ Z^0 $\end{document} boson tagged b-jets in heavy-ion collisions, which was performed using a Monte Carlo transport model. We find that the medium modification of the \begin{document}$ \Delta\phi_{bZ} $\end{document} for \begin{document}$ Z^0$\end{document} + b-jet has a weaker dependence on \begin{document}$ \Delta\phi_{bZ} $\end{document} than that for \begin{document}$ Z^0$\end{document} + jet, and the modification patterns are sensitive to the initial jet \begin{document}$ p_T $\end{document} distribution. Additionally, with the high purity of the quark jet in \begin{document}$ Z^0$\end{document} + (b-) jet production, we calculate the momentum imbalance \begin{document}$ x_{bZ} $\end{document} and the nuclear modification factor \begin{document}$ I_{AA} $\end{document} of \begin{document}$ Z^0$\end{document} + b-jet in Pb+Pb collisions. We observe a smaller \begin{document}$ \Delta \langle x_{jZ} \rangle $\end{document} and larger \begin{document}$ I_{AA} $\end{document} of \begin{document}$ Z^0$\end{document} + b-jet in Pb+Pb collisions relative to those of \begin{document}$ Z^0$\end{document} + jet, which may be an indication of the mass effect of jet quenching and can be tested in future measurements.     

Direct CP violation of three body decay processes from the resonance effect

The physical state of \begin{document}$ \rho-\omega-\phi $\end{document} mesons can be mixed using the unitary matrix. The decay processes \begin{document}$ \omega \rightarrow \pi^{+}\pi^{-} $\end{document} and \begin{document}$ \phi \rightarrow \pi^{+}\pi^{-} $\end{document} originate from isospin symmetry breaking. The \begin{document}$ \rho-\omega $\end{document}, \begin{document}$ \rho-\phi $\end{document}, and \begin{document}$ \omega-\phi $\end{document} interferences lead to a resonance contribution to produce strong phases. \begin{document}$ CP $\end{document} violation is considered from isospin symmetry breaking due to the new strong phase of the first order. \begin{document}$ CP $\end{document} violation can be enhanced greatly for the decay process \begin{document}$ B^{0}\rightarrow \pi^+\pi^{-}\eta^{(')} $\end{document} when the invariant masses of \begin{document}$ \pi^+\pi^{-} $\end{document} pairs are in the area around the \begin{document}$ \omega $\end{document} resonance range and \begin{document}$ \phi $\end{document} resonance range in perturbative QCD. We also discuss the possibility of searching for the predicted \begin{document}$ CP $\end{document} violation at the LHC.     

Investigating S-wave bound states composed of two pseudoscalar mesons

In this study, we systematically investigated two-pseudoscalar meson systems with the Bethe-Salpeter equation in the ladder and instantaneous approximations. By solving the Bethe-Salpeter equation numerically with the kernel containing the one-particle exchange diagrams, we found that the \begin{document}$ K\bar{K} $\end{document}, \begin{document}$ DK $\end{document}, \begin{document}$ B\bar{K} $\end{document}, \begin{document}$ D\bar{D} $\end{document}, \begin{document}$ B\bar{B} $\end{document}, \begin{document}$ BD $\end{document}, \begin{document}$ D\bar{K} $\end{document}, \begin{document}$ BK $\end{document}, and \begin{document}$ B\bar{D} $\end{document} systems with \begin{document}$ I=0 $\end{document} can exist as bound states. We also studied the contributions from heavy meson (\begin{document}$ J/\psi $\end{document} and \begin{document}$\Upsilon $\end{document}) exchanges and found that the contributions from heavy meson exchanges cannot be ignored.     

QCD sum rule study for hidden-strange pentaquarks

Inspired by the LHCb observations of hidden-charm \begin{document}$ P_{c(s)} $\end{document} states, we study their hidden-strange analog\begin{document}$ P_s $\end{document} states in both the \begin{document}$ [udu][\bar ss] $\end{document} and \begin{document}$ [uds][\bar su] $\end{document} configurations. We investigate \begin{document}$ P_s $\end{document} pentaquark states in the \begin{document}$ p\eta^\prime $\end{document}, \begin{document}$ p\phi $\end{document}, \begin{document}$ \Lambda K $\end{document}, \begin{document}$ \Sigma K $\end{document}, and \begin{document}$ \Sigma^\ast K^\ast $\end{document} structures with \begin{document}$J^P ={1}/{2}^-$\end{document} and \begin{document}$ \Sigma ^\ast K $\end{document} and \begin{document}$ \Sigma K^\ast $\end{document} with \begin{document}$J^P = {3}/{2}^-$\end{document} and calculate their masses in the framework of QCD sum rules. Our numerical results show that the extracted hadron masses for all the \begin{document}$ p\eta^\prime $\end{document}, \begin{document}$ p\phi $\end{document}, \begin{document}$ \Lambda K $\end{document}, \begin{document}$ \Sigma K $\end{document}, and \begin{document}$ \Sigma^\ast K^\ast $\end{document} structures are significantly higher than the \begin{document}$ \Sigma K $\end{document} mass threshold, and the masses for \begin{document}$ \Sigma ^\ast K $\end{document} and \begin{document}$ \Sigma K^\ast $\end{document}are also higher than the threshold of the corresponding hadron; hence, no bound state exists in such channels, which is consistent with the current experimental status.     

Exploring HVV amplitudes with CP violation using decomposition and the on-shell scattering amplitude method

\begin{document}$ CP $\end{document} violation may play an important role in baryogenesis in the early universe and should be examined comprehensively at colliders. We study the \begin{document}$ CP $\end{document} properties of \begin{document}$ HVV $\end{document} vertexes between Higgs and gauge boson pairs by defining a \begin{document}$ CP $\end{document} violation phase angle ξ, which indicates the mixture of \begin{document}$ CP $\end{document}-even and \begin{document}$ CP $\end{document}-odd Higgs states in \begin{document}$ HVV $\end{document} in new physics. A series of \begin{document}$ HVV $\end{document} amplitudes, \begin{document}$ H\to\gamma\gamma, H\to\gamma V\to \gamma \ell\ell $\end{document}, and \begin{document}$ H\to VV\to 4\ell $\end{document}, with a \begin{document}$ CP $\end{document} phase angle are studied systematically to explicitly explain why \begin{document}$ CP $\end{document} violation can only be probed independently in the \begin{document}$ 4\ell $\end{document} process. We obtain a novel amplitude decomposition relation that illustrates that if two preconditions (multilinear momentum dependent vertexes, and the current \begin{document}$ J_\mu $\end{document} of \begin{document}$ V\to \ell^+ \ell^- $\end{document} is formally proportional to a photon's polarization vector) are satisfied, a higher-point amplitude can be decomposed into a summation of a series of lower-point amplitudes. As a practical example, the amplitude of the \begin{document}$ H\to\gamma V\to \gamma \ell\ell $\end{document} and \begin{document}$ H\to VV\to 4\ell $\end{document} processes can be decomposed into a summation of many \begin{document}$ H\to\gamma\gamma $\end{document} amplitudes. We calculate these amplitudes in the framework of the on-shell scattering amplitude method, considering both massless and massive vector gauge bosons with the \begin{document}$ CP $\end{document} violation phase angle. The above two approaches provide consistent results and clearly reveal the \begin{document}$ CP $\end{document} violation ξ dependence in the amplitudes.     

Λb → Λc form factors from QCD light-cone sum rules

In this study, we calculate the transition form factors of \begin{document}$ \Lambda_b $\end{document} decaying into \begin{document}$ \Lambda_c $\end{document} within the framework of light-cone sum rules with the distribution amplitudes (DAs) of the \begin{document}$ \Lambda_b $\end{document}-baryon. In the hadronic representation of the correlation function, we isolate both the \begin{document}$ \Lambda_c $\end{document} and \begin{document}$ \Lambda_c^* $\end{document} states so that the \begin{document}$ \Lambda_b \rightarrow \Lambda_c $\end{document}form factors can be obtained without ambiguity. We investigate the P-type and A-type currents to interpolate light baryons for comparison because the interpolation current for the baryon state is not unique. We also employ three parametrization models for the DAs of \begin{document}$ \Lambda_b $\end{document} in the numerical calculation. We present the numerical predictions for the \begin{document}$ \Lambda_b \rightarrow \Lambda_c $\end{document} form factors and branching fractions, averaged forward-backward asymmetry, averaged final hadron polarization, and averaged lepton polarization of the \begin{document}$ \Lambda_b \to \Lambda_c \ell\mu $\end{document} decays, as well as the ratio of the branching ratios \begin{document}$ R_{\Lambda_c} $\end{document}. The predicted \begin{document}$ R_{\Lambda_c} $\end{document} is consistent with LHCb data.     

Open charm mesons and charmonia in magnetized strange hadronic matter

We investigate the in-medium masses of open charm mesons (D(\begin{document}$ D^0 $\end{document}, \begin{document}$ D^+ $\end{document}), \begin{document}$ \bar{D} $\end{document}(\begin{document}$ \bar{D^0} $\end{document}, \begin{document}$ D^- $\end{document}), \begin{document}$ D_s $\end{document}(\begin{document}$ {D_{s}}^+ $\end{document}, \begin{document}$ {D_{s}}^- $\end{document})) and charmonium states (\begin{document}$ J/\psi $\end{document}, \begin{document}$ \psi(3686) $\end{document}, \begin{document}$ \psi(3770) $\end{document}, \begin{document}$ \chi_{c0} $\end{document}, \begin{document}$ \chi_{c2} $\end{document}) in strongly magnetized isospin asymmetric strange hadronic matter using a chiral effective model. In the presence of a magnetic field, the number and scalar densities of charged baryons have contributions from Landau energy levels. The mass modifications of open charm mesons result from their interactions with nucleons, hyperons, and the scalar fields (the non-strange field σ, strange field ζ, and isovector field δ) in the presence of a magnetic field. The mass modifications of the charmonium states result from the modification of gluon condensates in a medium simulated by the variation in the dilaton field (χ) in the chiral effective model. The effects of finite quark masses are also incorporated in the trace of the energy-momentum tensor in quantum chromodynamics to investigate the mass shifts of charmonium states. The in-medium masses of open charm mesons and charmonia are observed to decrease with an increase in baryon density. The charged \begin{document}$ D^+ $\end{document}, \begin{document}$ D^- $\end{document}, \begin{document}$ {D_{s}}^+ $\end{document}, and \begin{document}$ {D_{s}}^- $\end{document} mesons have additional positive mass shifts due to Landau quantization in the presence of a magnetic field. The effects of the strangeness fraction are observed to be more dominant for \begin{document}$ \bar{D} $\end{document} mesons compared with D mesons. The mass shifts of charmonia are observed to be larger in hyperonic media compared with nuclear media when the effect of the finite quark mass term is neglected. These medium mass modifications can have observable consequences on the production of the open charm mesons and charmonia in high-energy asymmetric heavy-ion collision experiments.     

Double-heavy tetraquarks with strangeness in the chiral quark model

Recently, some progress has been made in the experiments on double-heavy tetraquarks, such as \begin{document}$ T_{cc} $\end{document} reported by the LHCb Collaboration and \begin{document}$ X_{cc\bar{s}\bar{s}} $\end{document} reported by the Belle Collaboration. Coming on the heels of our previous work about \begin{document}$ T_{cc} $\end{document} and \begin{document}$ T_{bb} $\end{document}, we present a study on the bound and resonance states of their companions, \begin{document}$ QQ\bar{q}\bar{s} $\end{document} (\begin{document}$ Q=c,b; q=u, s $\end{document}) tetraquarks with strange flavor in the chiral quark model. Two pictures, meson-meson and diquark-antidiquark ones, and their couplings were considered in our calculations. Isospin violation was neglected herein. Our numerical analysis indicated that the states \begin{document}$ cc\bar{u}\bar{s} $\end{document} with \begin{document}$ \dfrac{1}{2}(1^+) $\end{document} and \begin{document}$ bb\bar{u}\bar{s} $\end{document} with \begin{document}$ \dfrac{1}{2}(1^+) $\end{document} are the most promising stable states against strong interactions. Besides, we found several resonance states for the double-heavy strange tetraquarks with the real scaling method.     

Charged-current non-standard neutrino interactions at the LHC and HL-LHC

A series of new physics scenarios predict the existence of the extra charged gauge boson \begin{document}$ W' $\end{document}, which can induce charged-current (CC) non-standard neutrino interactions (NSIs). The theoretical constraints on the simplified \begin{document}$ W' $\end{document} model and further on the CC NSI parameters \begin{document}$ \widetilde{\epsilon}^{ qq'Y}_{\alpha\beta} $\end{document} from partial wave unitarity and \begin{document}$ W' $\end{document} decays are considered. The sensitivity of the process \begin{document}$ p p \rightarrow W'\rightarrow \ell\nu $\end{document} to the \begin{document}$ W' $\end{document} model at the LHC and high-luminosity (HL) LHC experiments is investigated by estimating the expected constraints on \begin{document}$ \widetilde{\epsilon}^{qq'Y}_{\alpha\beta} $\end{document} (\begin{document}$ \alpha = \beta = e $\end{document} or μ) using a Monte-Carlo (MC) simulation. We find that the interference effect plays an important role, and the LHC can strongly constrain \begin{document}$ \widetilde{\epsilon}^{qq'L}_{\alpha\beta} $\end{document}. Compared with those at the \begin{document}$ 13 \;{\rm TeV} $\end{document} LHC with \begin{document}$ {\cal{L}}=139\;{\rm fb}^{-1} $\end{document}, the expected constraints at the \begin{document}$ 14 \;{\rm TeV} $\end{document} LHC with \begin{document}$ {\cal{L}}=3\;{\rm ab}^{-1} $\end{document} can be strengthened to approximately one order of magnitude.     

Color-flavor dependence of the Nambu-Jona-Lasinio model and QCD phase diagram

We study the dynamical chiral symmetry breaking/restoration for various numbers of light quarks flavors \begin{document}$ N_f $\end{document} and colors \begin{document}$ N_c $\end{document} using the Nambu-Jona-Lasinio (NJL) model of quarks in the Schwinger-Dyson equation framework, dressed with a color-flavor dependence of effective coupling. For fixed \begin{document}$ N_f = 2 $\end{document} and varying \begin{document}$ N_c $\end{document}, we observe that the dynamical chiral symmetry is broken when \begin{document}$ N_c $\end{document} exceeds its critical value \begin{document}$ N^{c}_{c}\approx2.2 $\end{document}. For a fixed \begin{document}$ N_c = 3 $\end{document} and varying \begin{document}$ N_f $\end{document}, we observe that the dynamical chiral symmetry is restored when \begin{document}$ N_f $\end{document} reaches its critical value \begin{document}$ N^{c}_{f}\approx8 $\end{document}. Strong interplay is observed between \begin{document}$ N_c $\end{document} and \begin{document}$ N_f $\end{document}, i.e., larger values of \begin{document}$ N_c $\end{document} tend to strengthen the dynamical generated quark mass and quark-antiquark condensate, while higher values of \begin{document}$ N_f $\end{document} suppress both parameters. We further sketch the quantum chromodynamics (QCD) phase diagram at a finite temperature T and quark chemical potential μ for various \begin{document}$ N_c $\end{document} and \begin{document}$ N_f $\end{document}. At finite T and μ, we observe that the critical number of colors \begin{document}$ N^{c}_c $\end{document} is enhanced, whereas the critical number of flavors \begin{document}$ N^{c}_f $\end{document} is suppressed as T and μ increase. Consequently, the critical temperature \begin{document}$ T_c $\end{document}, \begin{document}$ \mu_c $\end{document}, and co-ordinates of the critical endpoint \begin{document}$ (T^{E}_c,\mu^{E}_c) $\end{document} in the QCD phase diagram are enhanced as \begin{document}$ N_c $\end{document} increases and suppressed when \begin{document}$ N_f $\end{document} increases. Our findings agree with the lattice QCD and Schwinger-Dyson equations predictions.     

Determining the nuclear temperature dependence on source neutron-proton asymmetry in heavy-ion reactions at intermediate energy

In this article, we investigate the dependence of nuclear temperature on emitting source neutron-proton (\begin{document}$ N/Z $\end{document}) asymmetry with light charged particles (LCPs) and intermediate mass fragments (IMFs) generated from intermediate-velocity sources in thirteen reaction systems with different \begin{document}$ N/Z $\end{document} asymmetries, \begin{document}$ ^{64} \rm{Zn} $\end{document} on \begin{document}$ ^{112} \rm{Sn} $\end{document}, and \begin{document}$ ^{70} \rm{Zn} $\end{document}, \begin{document}$ ^{64} \rm{Ni} $\end{document} on \begin{document}$ ^{112,124} \rm{Sn} $\end{document}, \begin{document}$ ^{58,64} \rm{Ni} $\end{document}, \begin{document}$ ^{197} \rm{Au} $\end{document}, and \begin{document}$ ^{232} \rm{Th} $\end{document} at 40 MeV/nucleon. The apparent temperature values of LCPs and IMFs from different systems are deduced from the measured yields using two helium-related and eight carbon-related double isotope ratio thermometers, respectively. Then, the sequential decay effect on the experimental apparent temperature deduction with the double isotope ratio thermometers is quantitatively corrected explicitly with the aid of the quantum statistical model. The present treatment is an improvement compared to our previous studies in which an indirect method was adopted to qualitatively consider the sequential decay effect. A negligible \begin{document}$ N/Z $\end{document} asymmetry dependence of the real temperature after the correction is quantitatively addressed in heavy-ion reactions at the present intermediate energy, where a change of 0.1 units in source \begin{document}$ N/Z $\end{document} asymmetry corresponds to an absolute change in temperature of an order of 0.03 to 0.29 MeV on average for LCPs and IMFs. This conclusion is in close agreement with that inferred qualitatively via the indirect method in our previous studies.     

Neutron skin thickness of 90Zr and symmetry energy constrained by charge exchange spin-dipole excitations

The charge exchange spin-dipole (SD) excitations of \begin{document}$ ^{90} $\end{document}Zr are studied using the Skyrme Hartee-Fock plus proton-neutron random phase approximation with SAMi-J interactions. The experimental value of the model-independent sum rule obtained from the SD strength distributions of \begin{document}$ ^{90} $\end{document}Zr(p, n)\begin{document}$ ^{90} $\end{document}Nb and \begin{document}$ ^{90} $\end{document}Zr(n, p)\begin{document}$ ^{90} $\end{document}Y is used to deduce the neutron skin thickness. The neutron skin thickness \begin{document}$ \Delta r_{np} $\end{document} of \begin{document}$ ^{90} $\end{document}Zr is extracted as \begin{document}$ 0.083\pm0.032 $\end{document} fm, which is similar to the results of other studies. Based on the correlation analysis of the neutron skin thickness \begin{document}$ \Delta r_{np} $\end{document} and the nuclear symmetry energy J as well as its slope parameter L, a constraint from the extracted \begin{document}$ \Delta r_{np} $\end{document} leads to the limitation of J to \begin{document}$ 29.2 \pm 2.6 $\end{document} MeV and L to \begin{document}$ 53.3 \pm 28.2 $\end{document} MeV.     

Electromagnetic field produced in high-energy small collision systems within charge density models of nucleons

Recent experiments show that \begin{document}$ \Delta\gamma $\end{document}, an observable designed to detect the chiral magnetic effect (CME), in small collision systems (\begin{document}$ p+A $\end{document}) is similar to that in heavy ion collisions (\begin{document}$ A+A $\end{document}). This introduces a challenge to the existence of the CME because it is believed that no azimuthal correlation exists between the orientation of the magnetic field (\begin{document}$ \Phi_B $\end{document}) and participant plane (\begin{document}$ \Phi_2 $\end{document}) in small collision systems. In this work, we introduce three charge density models to describe the inner charge distributions of protons and neutrons and calculate the electric and magnetic fields produced in small \begin{document}$ p+A $\end{document} collisions at both RHIC and LHC energies. Our results show that the contribution of the single projectile proton is the main contributor to the magnetic field after averaging over all participants. The azimuthal correlation between \begin{document}$ \Phi_B $\end{document} and \begin{document}$ \Phi_2 $\end{document} is small but not vanished. Additionally, owing to the large fluctuation in field strength, the magnetic-field contribution to \begin{document}$ \Delta\gamma $\end{document} may be large.     

Reaction 55Mn + 159Tb : preparation for the synthesis of new elements

The complete fusion reaction of \begin{document}$^{55}$\end{document}Mn + \begin{document}$^{159}$\end{document}Tb was studied on the gas-filled recoil separator SHANS2. Nineteen ER - α\begin{document}$_{1}$\end{document} - α\begin{document}$_{2}$\end{document} decay chains from \begin{document}$^{210}$\end{document}Th produced from the 4n evaporation channel were observed. The α-particle energy and half-life of \begin{document}$^{210}$\end{document}Th were determined as 7922(14) keV and 14(4) ms, respectively. In addition, the decay properties of \begin{document}$E_{\alpha}$\end{document} = 7788(14) keV and \begin{document}$T_{1/2}$\end{document} = 36\begin{document}$^{+15}_{-8}$\end{document} ms were obtained for \begin{document}$^{211}$\end{document}Th. The measured α decay properties of \begin{document}$^{210}$\end{document}Th and \begin{document}$^{211}$\end{document}Th were consistent with literature data. The cross sections were measured to be 0.59\begin{document}$^{+0.25}_{-0.23}$\end{document} nb and 0.19\begin{document}$^{+0.12}_{-0.09}$\end{document} nb for \begin{document}$^{210}$\end{document}Th and \begin{document}$^{211}$\end{document}Th, respectively. The equilibrium charge state of the recoiled nucleus \begin{document}$^{210}$\end{document}Th was determined experimentally. The new data were helpful for estimating the equilibrium charge states of elements 119 and 120, which could be produced via the \begin{document}$^{240}$\end{document}Pu(\begin{document}$^{55}$\end{document}Mn, 3n)\begin{document}$^{292}$\end{document}119 and \begin{document}$^{243}$\end{document}Am(\begin{document}$^{55}$\end{document}Mn, 3n)\begin{document}$^{295}$\end{document}120 reactions, respectively.     

Effects of Λ hyperons on the deformations of even–even nuclei

The deformations of multi-\begin{document}$ {\Lambda} $\end{document} hypernuclei corresponding to even–even core nuclei ranging from \begin{document}$ ^8 $\end{document}Be to \begin{document}$ ^{40} $\end{document}Ca with 2, 4, 6, and 8 hyperons are studied using the deformed Skyrme–Hartree–Fock approach. It is found that the deformations are reduced when adding 2 or 8 \begin{document}$ {\Lambda} $\end{document} hyperons, but enhanced when adding 4 or 6 \begin{document}$ {\Lambda} $\end{document} hyperons. These differences are attributed to the fact that \begin{document}$ {\Lambda} $\end{document} hyperons are filled gradually into the three deformed \begin{document}$ p $\end{document} orbits, of which the [110]1/2\begin{document}$ ^- $\end{document} orbit is prolately deformed and the degenerate [101]1/2\begin{document}$ ^- $\end{document} and [101]3/2\begin{document}$ ^- $\end{document} orbits are oblately deformed.     

Using simulated Tianqin gravitational wave data and electromagnetic wave data to study the coincidence problem and Hubble tension problem

In this study, we used electromagnetic wave data (H0LiCOW, \begin{document}$ H(z) $\end{document}, SNe) and gravitational wave data (Tianqin) to constrain the interacting dark energy (IDE) model and investigate the Hubble tension and coincidence problems. By combining these four types of data (Tianqin+H0LiCOW+SNe+\begin{document}$ H(z) $\end{document}), we obtained the following parameter values with a confidence interval of \begin{document}$ 1\sigma $\end{document}: \begin{document}$ \Omega_m=0.36\pm0.18 $\end{document}, \begin{document}$ \omega_x=-1.29^{+0.61}_{-0.23} $\end{document}, \begin{document}$ \xi=3.15^{+0.36}_{-1.1} $\end{document}, and \begin{document}$H_0=70.04\pm $\end{document}\begin{document}$ 0.42~ {\rm kms}^{-1}{\rm Mpc}^{-1}$\end{document}. According to our results, the best value of \begin{document}$ H_0 $\end{document} shows that the Hubble tension problem can be alleviated to some extent. In addition, the center value of \begin{document}$ \xi+3\omega_x = -0.72^{+2.19}_{-1.19}(1\sigma) $\end{document} indicates that the coincidence problem is slightly alleviated. However, \begin{document}$ \xi+3\omega_x = 0 $\end{document} is still within the \begin{document}$ 1\sigma $\end{document} error range, which indicates that the ΛCDM model is still the model in best agreement with the observational data at present. Finally, we compared the constraint results of the electromagnetic and gravitational waves on the model parameters and found that the constraint effect of electromagnetic wave data on model parameters is better than that of simulated Tianqin gravitational wave data.     

Sequential single pion production explaining the dibaryon "d*(2380)" peak

In this study, we investigate the two step sequential one pion production mechanism, that is, \begin{document}$ np(I=0)\to $\end{document}\begin{document}$ \pi^-pp $\end{document} followed by the fusion reaction \begin{document}$ pp\to \pi^+d $\end{document}, to describe the \begin{document}$ np\to \pi^+\pi^-d $\end{document} reaction with \begin{document}$ \pi^+\pi^- $\end{document} in state \begin{document}$ I=0 $\end{document}. In this reaction, a narrow peak identified with a "\begin{document}$ d(2380) $\end{document}" dibaryon has been previously observed. We discover that the second reaction step \begin{document}$ pp\to \pi^+d $\end{document} is driven by a triangle singularity that determines the position of the peak of the reaction and the high strength of the cross section. The combined cross section of these two mechanisms produces a narrow peak with a position, width, and strength, that are compatible with experimental observations within the applied approximations made. This novel interpretation of the peak accomplished without invoking a dibaryon explains why this peak has remained undetected in other reactions.     

Dependence of the tidal deformability of neutron stars on the nuclear equation of state

Within the Bayesian framework, using an explicitly isospin-dependent parametric equation of state (EOS) for the core of neutron stars (NSs), we studied how the NS EOS behaves when we confront it with the tidal deformabilities \begin{document}$ \Lambda_{1.4} $\end{document} of canonical NSs with different error and different lower boundaries, and with the tidal deformabilities of massive NSs. We found that it does not significantly improve the constraints on the NS EOS but has a weak effect on narrowing down the slope parameter of the symmetry energy by decreasing the measurement errors of \begin{document}$ \Lambda_{1.4} $\end{document}. Both the isospin-dependent and isospin-independent parts of the NS EOS were significantly constrained and raised as the tidal deformabilities of massive NSs were adopted in the calculations, especially in high-density regions. We also found that \begin{document}$ \Lambda_{1.4} $\end{document} is more competent to limit the curvature parameter than the slope parameter of the symmetry energy, whereas the opposite occurs for the radius of canonical NSs \begin{document}$ R_{1.4} $\end{document}. The tidal deformability of an NS with two times the solar mass \begin{document}$ \Lambda_{2.0} $\end{document} is more sensitive to skewness than the curvature parameter of the symmetry energy, and \begin{document}$ \Lambda_{1.4} $\end{document} and \begin{document}$ R_{1.4} $\end{document} have no correlation with the former.