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Published:
, doi: 10.1088/1674-1137/ac878b
Abstract:
We study the dynamical properties of the thermodynamic phase transition (PT) of a charged AdS black hole (BH) with a global monopole via the Gibbs free energy landscape and reveal the effects of the global monopole on the kinetics of thermodynamic PTs. First, we briefly review the thermodynamics of a charged AdS BH with a global monopole. Then, we introduce the Gibbs free energy landscape to investigate the thermodynamic stability of the BH states. Because of thermal fluctuations, the small black hole (SBH) state can transit to a large black hole (LBH) state, and vice versa. Further, we use the Fokker-Planck equation with the reflecting boundary condition to study the probability evolution of the BH state with and without a global monopole separately. It is found that for both the SBH and LBH states, the global monopole could slow down the evolution of the BH state. In addition, we obtain the relationship between the first passage time and the monopole parameter η. The result shows that as the monopole parameter η increases, the mean first passage time becomes longer for both the SBH and LBH states.
We study the dynamical properties of the thermodynamic phase transition (PT) of a charged AdS black hole (BH) with a global monopole via the Gibbs free energy landscape and reveal the effects of the global monopole on the kinetics of thermodynamic PTs. First, we briefly review the thermodynamics of a charged AdS BH with a global monopole. Then, we introduce the Gibbs free energy landscape to investigate the thermodynamic stability of the BH states. Because of thermal fluctuations, the small black hole (SBH) state can transit to a large black hole (LBH) state, and vice versa. Further, we use the Fokker-Planck equation with the reflecting boundary condition to study the probability evolution of the BH state with and without a global monopole separately. It is found that for both the SBH and LBH states, the global monopole could slow down the evolution of the BH state. In addition, we obtain the relationship between the first passage time and the monopole parameter η. The result shows that as the monopole parameter η increases, the mean first passage time becomes longer for both the SBH and LBH states.
Published:
, doi: 10.1088/1674-1137/ac82e1
Abstract:
In the standard model effective field theory, operators involving the top quark are generally difficult to probe and can generate sizable loop contributions to electroweak precision observables measured by past and future lepton colliders. Could the high precision of electroweak measurements compensate for loop suppression and provide competitive reaches on these operators? Would the inclusion of these contributions introduce too many additional parameters for a meaningful global electroweak analysis to be performed? In this paper, we perform a detailed phenomenological study to address these two important questions. Focusing on eight dimension-6 operators that generate anomalous couplings between electroweak gauge bosons and third-generation quarks, we calculate their one loop contributions to$ e^+e^- \to f\bar{f} $ processes, both on and off the Z-pole, and the $ e^-e^+ \to WW $ process. A global analysis is performed with these eight operators and those that contribute to the above processes at tree level using measurements at the LEP, SLC, and several low energy experiments. We find that although current electroweak precision measurements are sensitive to the one-loop effects of top-quark operators, it is difficult to separate them from the operators that contribute at tree level, making a global analysis rather challenging. Under further assumptions (for instance, new physics contributes to only third generation quark operators and the S and T parameters), competitive reaches may be obtained in a global fit. Another important finding of our study is that the two operators that generate the dipole interactions of the bottom quark have a significant impact on the Z-pole measurements and should not be omitted. We also discuss the implications of the recently reported W-boson mass measurement at the CDF for our results. Finally, we estimate the reaches of future lepton colliders in probing top-quark operators with precision electroweak measurements.
In the standard model effective field theory, operators involving the top quark are generally difficult to probe and can generate sizable loop contributions to electroweak precision observables measured by past and future lepton colliders. Could the high precision of electroweak measurements compensate for loop suppression and provide competitive reaches on these operators? Would the inclusion of these contributions introduce too many additional parameters for a meaningful global electroweak analysis to be performed? In this paper, we perform a detailed phenomenological study to address these two important questions. Focusing on eight dimension-6 operators that generate anomalous couplings between electroweak gauge bosons and third-generation quarks, we calculate their one loop contributions to
Published:
, doi: 10.1088/1674-1137/ac87f1
Abstract:
It is well known that when vacuum polarization emerges in quantum electrodynamics, the non-linear interaction between electromagnetic fields should be considered. Moreover, the corresponding field of non-linear electrodynamics can have important effects on black hole physics. In this work, we focus on the relationship between an observable quantity, that is, the shadow radius, and the first-order phase transition of non-linear charged AdS black holes in the framework of Einstein-power-Yang-Mills gravity. The results show that, under a certain condition, there exists a first-order phase transition from the viewpoint of both the shadow radius and horizon radius, which depend on temperature (or pressure). From the viewpoint of the shadow radius, the phase transition temperature is higher than that from the viewpoint of the horizon radius under the same condition. This may be due to the non-linear Yang Mills charge and the gravitational effect. This indicates that the shadow radius can be regarded as a probe to reveal the thermodynamic phase transition information of black holes. The thermal profiles of coexistent large and small black hole phases when the system is undergoing the phase transition are presented for two different values of the non-linear Yang Mills charge parameter:$ \gamma=1,\; 1.5 $ . Furthermore, the effects of the non-linear Yang Mills charge parameter on the shadow radius and thermal profile are investigated.
It is well known that when vacuum polarization emerges in quantum electrodynamics, the non-linear interaction between electromagnetic fields should be considered. Moreover, the corresponding field of non-linear electrodynamics can have important effects on black hole physics. In this work, we focus on the relationship between an observable quantity, that is, the shadow radius, and the first-order phase transition of non-linear charged AdS black holes in the framework of Einstein-power-Yang-Mills gravity. The results show that, under a certain condition, there exists a first-order phase transition from the viewpoint of both the shadow radius and horizon radius, which depend on temperature (or pressure). From the viewpoint of the shadow radius, the phase transition temperature is higher than that from the viewpoint of the horizon radius under the same condition. This may be due to the non-linear Yang Mills charge and the gravitational effect. This indicates that the shadow radius can be regarded as a probe to reveal the thermodynamic phase transition information of black holes. The thermal profiles of coexistent large and small black hole phases when the system is undergoing the phase transition are presented for two different values of the non-linear Yang Mills charge parameter:
Published:
, doi: 10.1088/1674-1137/ac8539
Abstract:
Neutron-induced nuclear recoil background is critical to dark matter searches in the PandaX-4T liquid xenon experiment. In this study, we investigate the features of neutron background in liquid xenon and evaluate its contribution in single scattering nuclear recoil events using three methods. The first method is fully based on Monte Carlo simulations. The last two are data-driven methods that also use multiple scattering signals and high energy signals in the data. In the PandaX-4T commissioning data with an exposure of 0.63 tonne-year, all these methods give a consistent result, i.e., there are$ 1.15\pm0.57 $ neutron-induced backgrounds in the dark matter signal region within an approximated nuclear recoil energy window between 5 and 100 keV.
Neutron-induced nuclear recoil background is critical to dark matter searches in the PandaX-4T liquid xenon experiment. In this study, we investigate the features of neutron background in liquid xenon and evaluate its contribution in single scattering nuclear recoil events using three methods. The first method is fully based on Monte Carlo simulations. The last two are data-driven methods that also use multiple scattering signals and high energy signals in the data. In the PandaX-4T commissioning data with an exposure of 0.63 tonne-year, all these methods give a consistent result, i.e., there are
Published:
, doi: 10.1088/1674-1137/ac89d0
Abstract:
Conceptually, radii are amongst the simplest Poincaré-invariant properties that can be associated with hadrons and light nuclei. Accurate values of these quantities are necessary so that one may judge the character of putative solutions to the strong interaction problem within the Standard Model. However, limiting their ability to serve in this role, recent measurements and new analyses of older data have revealed uncertainties and imprecisions in the radii of the proton, pion, kaon, and deuteron. In the context of radius measurement using electron+hadron elastic scattering, the past decade has shown that reliable extraction requires minimisation of bias associated with practitioner-dependent choices of data fitting functions. Different answers to that challenge have been offered; and this perspective describes the statistical Schlessinger point method (SPM), in unifying applications to proton, pion, kaon, and deuteron radii. Grounded in analytic function theory, independent of assumptions about underlying dynamics, free from practitioner-induced bias, and applicable in the same form to diverse systems and observables, the SPM returns an objective expression of the information contained in any data under consideration. Its robust nature and versatility make it suitable for use in many branches of experiment and theory.
Conceptually, radii are amongst the simplest Poincaré-invariant properties that can be associated with hadrons and light nuclei. Accurate values of these quantities are necessary so that one may judge the character of putative solutions to the strong interaction problem within the Standard Model. However, limiting their ability to serve in this role, recent measurements and new analyses of older data have revealed uncertainties and imprecisions in the radii of the proton, pion, kaon, and deuteron. In the context of radius measurement using electron+hadron elastic scattering, the past decade has shown that reliable extraction requires minimisation of bias associated with practitioner-dependent choices of data fitting functions. Different answers to that challenge have been offered; and this perspective describes the statistical Schlessinger point method (SPM), in unifying applications to proton, pion, kaon, and deuteron radii. Grounded in analytic function theory, independent of assumptions about underlying dynamics, free from practitioner-induced bias, and applicable in the same form to diverse systems and observables, the SPM returns an objective expression of the information contained in any data under consideration. Its robust nature and versatility make it suitable for use in many branches of experiment and theory.
Published:
, doi: 10.1088/1674-1137/ac8a8c
Abstract:
The level structure of the double-magic nucleus 34Si (Z = 14, N = 20) was investigated by evaluating the available data. On the basis of experimental results from the beta-decay and fusion-evaporation reactions, we established the level scheme by assigning spin-parities up to 61+ at 6233 keV. The high energy positions of the excited states are consistent with the magicity at 34Si, such as the 22+ state of the spherical ground band at 4.519 MeV and the 3-, 4-, and 5- states of the one-particle one-hole cross-shell states at approximately 4.5 MeV. This nucleus, for a long time, has attracted much attention because of, on one side, a proton bubble structure in the ground state and, on the other side, a deformation in the second 0+ state, 02+. By a comparison of the constructed level scheme with the shell model calculations, we describe the emerging structures in the ground and second 0+ states and the negative-parity 3- states within the framework of the shell model context. We propose a deformed rotational band with the cascading 62+ − 41+ − 21+ transitions built on the 02+ state.
The level structure of the double-magic nucleus 34Si (Z = 14, N = 20) was investigated by evaluating the available data. On the basis of experimental results from the beta-decay and fusion-evaporation reactions, we established the level scheme by assigning spin-parities up to 61+ at 6233 keV. The high energy positions of the excited states are consistent with the magicity at 34Si, such as the 22+ state of the spherical ground band at 4.519 MeV and the 3-, 4-, and 5- states of the one-particle one-hole cross-shell states at approximately 4.5 MeV. This nucleus, for a long time, has attracted much attention because of, on one side, a proton bubble structure in the ground state and, on the other side, a deformation in the second 0+ state, 02+. By a comparison of the constructed level scheme with the shell model calculations, we describe the emerging structures in the ground and second 0+ states and the negative-parity 3- states within the framework of the shell model context. We propose a deformed rotational band with the cascading 62+ − 41+ − 21+ transitions built on the 02+ state.
Published:
, doi: 10.1088/1674-1137/ac8bc9
Abstract:
JUNO is a multi-purpose neutrino observatory under construction in the south of China. This publication presents new sensitivity estimates for the measurement of the$ \Delta m^2_{31} $ , $ \Delta m^2_{21} $ , $ \sin^2 \theta_{12} $ , and $ \sin^2 \theta_{13} $ oscillation parameters using reactor antineutrinos, which is one of the primary physics goals of the experiment. The sensitivities are obtained using the best knowledge available to date on the location and overburden of the experimental site, the nuclear reactors in the surrounding area and beyond, the detector response uncertainties, and the reactor antineutrino spectral shape constraints expected from the TAO satellite detector. It is found that the $ \Delta m^2_{21} $ and $ \sin^2 \theta_{12} $ oscillation parameters will be determined to better than 0.5% precision in six years of data collection. In the same period, the $ \Delta m^2_{31} $ parameter will be determined to about $ 0.2\ $ % precision for each mass ordering hypothesis. The new precision represents approximately an order of magnitude improvement over existing constraints for these three parameters.
JUNO is a multi-purpose neutrino observatory under construction in the south of China. This publication presents new sensitivity estimates for the measurement of the
Published:
, doi: 10.1088/1674-1137/ac878c
Abstract:
Exclusive$ \pi^0 $ electroproduction is analyzed within the handbag approach based on Generalized Parton Distribution (GPDs) factorization. We consider the leading-twist contribution together with the transversity effects. It is shown that the transversity GPDs $ H_{\rm T} $ and $ \bar E_{\rm T} $ are essential in the description of the $ \pi^0 $ cross section. Predictions for the future Electron-Ion Collider of China (EicC) energy range are provided. It is found that transversity dominance $ \sigma_{\rm T}\gg\sigma_{\rm L} $ , observed at low energies, is valid up to the EicC energy range.
Exclusive
Published:
, doi: 10.1088/1674-1137/ac80ee
Abstract:
In this study, we adopt the self-consistent Hartree-Fock-Bogoliubov (HFB) theory with the proton-neutron quasi-particle random phase approximation (pnQRPA) based on the Skyrme force for calculation of the β− decay half-lives for nuclei with N ~ 82 and 126 on possible r-process paths. In the calculations, the Skyrme interaction (e.g., SKO') is adopted, and the tensor interaction is added self-consistently in both HFB and QRPA calculations. We systematically study how the half-life is changed by varying the strength of the triplet-even (TE) and triplet-odd (TO) components as well as the IS pairing. We find that a variation in strength of the IS pairing of approximately 20% does not produce a substantial effect on β-decay rates with or without the tensor force, while a strength variation of the TO tensor force considerably affects the change in the β-decay half-lives for the very neutron rich N ~ 82 and 126 isotonic chains. In addition, with the inclusion of the tensor force, the GT decay becomes dominant for very neutron-rich nuclei.
In this study, we adopt the self-consistent Hartree-Fock-Bogoliubov (HFB) theory with the proton-neutron quasi-particle random phase approximation (pnQRPA) based on the Skyrme force for calculation of the β− decay half-lives for nuclei with N ~ 82 and 126 on possible r-process paths. In the calculations, the Skyrme interaction (e.g., SKO') is adopted, and the tensor interaction is added self-consistently in both HFB and QRPA calculations. We systematically study how the half-life is changed by varying the strength of the triplet-even (TE) and triplet-odd (TO) components as well as the IS pairing. We find that a variation in strength of the IS pairing of approximately 20% does not produce a substantial effect on β-decay rates with or without the tensor force, while a strength variation of the TO tensor force considerably affects the change in the β-decay half-lives for the very neutron rich N ~ 82 and 126 isotonic chains. In addition, with the inclusion of the tensor force, the GT decay becomes dominant for very neutron-rich nuclei.
Published:
, doi: 10.1088/1674-1137/ac7fe6
Abstract:
Color screening and parton inelastic scattering modify the heavy-quark antiquark potential in mediums consisting of particles from quantum chromodynamics (QCD), leading to the suppression of quarkonium production in relativistic heavy-ion collisions. Owing to the small charm/anti-charm ($ c\bar{c} $ ) pair production number in proton-nucleus (pA) collisions, the correlation between different $ c\bar{c} $ pairs is negligible, which makes the Schrödinger equation viable for tracking the evolution of only one $ c\bar{c} $ pair. We employ the time-dependent Schrödinger equation with an in-medium $ c\bar{c} $ potential to study the evolution of charmonium wave functions in a hydrodynamic-like QCD medium produced in pA collisions. We explore different parametrizations of real and imaginary parts of the $ c\bar{c} $ potential and calculate the nuclear modification factors ($R_{pA}$ ) of $ J/\psi $ and $ \psi(2S) $ in $ \sqrt{s_{NN}}=5.02 $ TeV energy p-Pb collisions at the Large Hadron Collider (LHC). Comparing strong and weak screening scenarios with experimental data in this approach, we arrive at the conclusion that color screening is weak at temperatures close to the deconfined phase transition. Moreover, the imaginary part of the potential is crucial in describing the experimental data, which is consistent with widely studied semi-classical approaches, where dissociation rates are essential.
Color screening and parton inelastic scattering modify the heavy-quark antiquark potential in mediums consisting of particles from quantum chromodynamics (QCD), leading to the suppression of quarkonium production in relativistic heavy-ion collisions. Owing to the small charm/anti-charm (
Published:
, doi: 10.1088/1674-1137/ac88bb
Abstract:
In the framework of the 3-3-1 model with neutral leptons, we investigate lepton-flavor-violating sources based on the Higgs mass spectrum, which has two neutral Higgs identified with the corresponding ones of the two-Higgs-doublet model. We note that at the$ 13\; {\rm{TeV}} $ scale of the LHC, the parameter space regions satisfy the experimental limits of $ e_i \rightarrow e_j\gamma $ decays. These regions depend heavily on the mixing of exotic leptons but are predicted to have large $ h^0_1\rightarrow \mu \tau $ signals. We also show that $ {\rm{Br}}(h^0_1\rightarrow \mu \tau) $ can reach a value of $ 10^{-4} $ .
In the framework of the 3-3-1 model with neutral leptons, we investigate lepton-flavor-violating sources based on the Higgs mass spectrum, which has two neutral Higgs identified with the corresponding ones of the two-Higgs-doublet model. We note that at the
Published:
, doi: 10.1088/1674-1137/ac8868
Abstract:
In this study, we investigate the collapsing scenario for the k-essence emergent Vaidya spacetime in the context of massive gravity's rainbow. For this study, we consider that the background metric is Vaidya spacetime in massive gravity's rainbow. We show that the k-essence emergent gravity metric closely resembles the new type of generalized Vaidya massive gravity metric with the rainbow deformations for null fluid collapse, where we consider the k-essence scalar field as a function solely of the advanced or the retarded time. The k-essence emergent Vaidya massive gravity rainbow mass function is also different. This new type k-essence emergent Vaidya massive gravity rainbow metric satisfies the required energy conditions. The existence of a locally naked central singularity and the strength and strongness of the singularities for the rainbow deformations of the k-essence emergent Vaidya massive gravity metric are the interesting outcomes of the present work.
In this study, we investigate the collapsing scenario for the k-essence emergent Vaidya spacetime in the context of massive gravity's rainbow. For this study, we consider that the background metric is Vaidya spacetime in massive gravity's rainbow. We show that the k-essence emergent gravity metric closely resembles the new type of generalized Vaidya massive gravity metric with the rainbow deformations for null fluid collapse, where we consider the k-essence scalar field as a function solely of the advanced or the retarded time. The k-essence emergent Vaidya massive gravity rainbow mass function is also different. This new type k-essence emergent Vaidya massive gravity rainbow metric satisfies the required energy conditions. The existence of a locally naked central singularity and the strength and strongness of the singularities for the rainbow deformations of the k-essence emergent Vaidya massive gravity metric are the interesting outcomes of the present work.
Published:
, doi: 10.1088/1674-1137/ac84ca
Abstract:
It is currently widely accepted that gluons, while massless at the level of the fundamental QCD Lagrangian, acquire an effective mass through the non-Abelian implementation of the classic Schwinger mechanism. The key dynamical ingredient that triggers the onset of this mechanism is the formation of composite massless poles inside the fundamental vertices of the theory. These poles enter the evolution equation of the gluon propagator and nontrivially affect the way the Slavnov-Taylor identities of the vertices are resolved, inducing a smoking-gun displacement in the corresponding Ward identities. In this article, we present a comprehensive review of the pivotal concepts associated with this dynamical scenario, emphasizing the synergy between functional methods and lattice simulations and highlighting recent advances that corroborate the action of the Schwinger mechanism in QCD.
It is currently widely accepted that gluons, while massless at the level of the fundamental QCD Lagrangian, acquire an effective mass through the non-Abelian implementation of the classic Schwinger mechanism. The key dynamical ingredient that triggers the onset of this mechanism is the formation of composite massless poles inside the fundamental vertices of the theory. These poles enter the evolution equation of the gluon propagator and nontrivially affect the way the Slavnov-Taylor identities of the vertices are resolved, inducing a smoking-gun displacement in the corresponding Ward identities. In this article, we present a comprehensive review of the pivotal concepts associated with this dynamical scenario, emphasizing the synergy between functional methods and lattice simulations and highlighting recent advances that corroborate the action of the Schwinger mechanism in QCD.
Published:
, doi: 10.1088/1674-1137/ac8653
Abstract:
We systematically study the magnetic dipole moments of multiquark states. In this study, the magnetic dipole moments of possible$ B^- B^{*-} $ , $ B^0 B^{*-} $ , $ B^- B^{*0} $ , $ B^0 B^{*0} $ , $ B_s^0 B^{*-} $ , $ B^- B_s^{*0} $ , $ B_s^{0} B^{*0} $ , $ B^0 B_s^{*0} $ , and $ B^0_s B_s^{*0} $ states are extracted using light-cone sum rules. We explore the magnetic dipole moments of these states in a molecular picture with spin-parity $ J^P = 1^+ $ . The magnetic dipole moments of hadrons include useful information on the distributions of internal charge and magnetization, which can be used to understand their geometrical shapes and quark-gluon organization. The results of the present study along with the spectroscopic parameters may help future theoretical and experimental research on the characteristics of doubly-bottom tetraquark states.
We systematically study the magnetic dipole moments of multiquark states. In this study, the magnetic dipole moments of possible
Published:
, doi: 10.1088/1674-1137/ac8867
Abstract:
The influence of the neck parameter on the fission dynamics at low excitation energy is studied based on the three-dimensional Langevin approach, in which the nuclear shape is described with the two-center shell model (TCSM) parametrization, and the elongation, mass asymmetry, and fragment deformation are set to be the generalized coordinates of the Langevin equation. We first study the influence of the neck parameter on the scission configuration. We find that there is almost no obvious correlation between the neck parameter$ \epsilon $ and mass asymmetry η at the scission point, indicating that $ \epsilon $ has no evident impact on the fragment mass distribution. The elongation $ Z_0/R_0 $ and its correlation with the mass asymmetry η at the scission point are clearly influenced by the neck parameter $ \epsilon $ , which has a strong effect on the total kinetic energy (TKE) distribution of the fragments. The pre-neutron emission fragment mass distributions for 14 MeV n+ $ ^{233,235,238} $ U and $ ^{239} $ Pu are calculated, and then, based on these results, the post-neutron emission fragment mass distributions are obtained by using the experimental data of prompt neutron emission. The calculated post-neutron emission fragment mass distributions can reproduce the experimental data well. The TKE distributions for 14 MeV n+ $ ^{235} $ U fission are calculated for $ \epsilon $ =0.25, 0.35, and 0.45, and the results show that the TKE distribution cannot be described very well for the three cases. However, the trend of the calculated TKE distribution with $ \epsilon $ is just as expected from the scission configuration calculations. The results with $ \epsilon $ =0.35 present a better agreement with the experiment data compared with the other two cases.
The influence of the neck parameter on the fission dynamics at low excitation energy is studied based on the three-dimensional Langevin approach, in which the nuclear shape is described with the two-center shell model (TCSM) parametrization, and the elongation, mass asymmetry, and fragment deformation are set to be the generalized coordinates of the Langevin equation. We first study the influence of the neck parameter on the scission configuration. We find that there is almost no obvious correlation between the neck parameter
Published:
, doi: 10.1088/1674-1137/ac80b4
Abstract:
The integrated luminosities of data samples collected in the BESIII experiment in 2016–2017 at center-of-mass energies between 4.19 and 4.28 GeV are measured with a precision better than 1% by analyzing large-angle Bhabha scattering events. The integrated luminosities of old datasets collected in 2010–2014 are updated by considering corrections related to detector performance, offsetting the effect of newly discovered readout errors in the electromagnetic calorimeter, which can haphazardly occur.
The integrated luminosities of data samples collected in the BESIII experiment in 2016–2017 at center-of-mass energies between 4.19 and 4.28 GeV are measured with a precision better than 1% by analyzing large-angle Bhabha scattering events. The integrated luminosities of old datasets collected in 2010–2014 are updated by considering corrections related to detector performance, offsetting the effect of newly discovered readout errors in the electromagnetic calorimeter, which can haphazardly occur.
Published:
, doi: 10.1088/1674-1137/ac84cc
Abstract:
From December 2019 to June 2021, the BESIII experiment collected approximately 5.85 fb−1 of data at center-of-mass energies between 4.61 and 4.95 GeV. This is the highest collision energy BEPCII has reached to date. The accumulated$e^+e^-$ annihilation data samples are useful for studying charmonium(-like) states and charmed-hadron decays. By adopting a novel method of analyzing the production of $\Lambda_{c}^{+}\bar{\Lambda}_{c}^{-}$ pairs in $e^+e^-$ annihilation, the center-of-mass energies are measured with a precision of $\sim$ 0.6 MeV. Integrated luminosities are measured with a precision of better than 1% by analyzing the events of large-angle Bhabha scattering. These measurements provide important inputs to analyses based on these data samples.
From December 2019 to June 2021, the BESIII experiment collected approximately 5.85 fb−1 of data at center-of-mass energies between 4.61 and 4.95 GeV. This is the highest collision energy BEPCII has reached to date. The accumulated
Published:
, doi: 10.1088/1674-1137/ac827b
Abstract:
The associated production of a dark particle and photon, represented as a mono-γ event, is a promising channel to probe particle content and dynamics in the dark sector. In this study, we investigate the properties of the mono-γ production of vector dark matter at future$ e^+e^- $ colliders. Photon-like and Pauli operators as well as triple gauge boson interactions involving dark matter are considered in the framework of effective field theory. We show that, in comparison with the Pauli operator, the triple gauge boson couplings are significantly more interesting in high energy colliders. Beam polarization effects are also analyzed, and we show that the experimental sensitivities cannot be significantly enhanced because of the smaller luminosity.
The associated production of a dark particle and photon, represented as a mono-γ event, is a promising channel to probe particle content and dynamics in the dark sector. In this study, we investigate the properties of the mono-γ production of vector dark matter at future
Published:
, doi: 10.1088/1674-1137/ac7eb3
Abstract:
In this study, we investigate formulas of the number of states with a given total spin I and isospin T for n nucleons in a single-j shell denoted by$ D_{IT} (j, n) $ . Talmi's recursion formulas for the number of states with a given z-axis projection of total spin are generalized by further considering the isospin couplings and are applied to derive explicit formulas of $ D_{IT} (j, n) $ .
In this study, we investigate formulas of the number of states with a given total spin I and isospin T for n nucleons in a single-j shell denoted by
Published:
, doi: 10.1088/1674-1137/ac80ef
Abstract:
The physical state of$ \rho-\omega-\phi $ mesons can be mixed using the unitary matrix. The decay processes $ \omega \rightarrow \pi^{+}\pi^{-} $ and $ \phi \rightarrow \pi^{+}\pi^{-} $ originate from isospin symmetry breaking. The $ \rho-\omega $ , $ \rho-\phi $ , and $ \omega-\phi $ interferences lead to a resonance contribution to produce strong phases. $ CP $ violation is considered from isospin symmetry breaking due to the new strong phase of the first order. $ CP $ violation can be enhanced greatly for the decay process $ B^{0}\rightarrow \pi^+\pi^{-}\eta^{(')} $ when the invariant masses of $ \pi^+\pi^{-} $ pairs are in the area around the $ \omega $ resonance range and $ \phi $ resonance range in perturbative QCD. We also discuss the possibility of searching for the predicted $ CP $ violation at the LHC.
The physical state of
Published:
, doi: 10.1088/1674-1137/ac878a
Abstract:
The flux-averaged cross-sections$\langle{\sigma(E_{\rm{\gamma max}})}\rangle$ for the reactions ${^{65}{\rm{Cu}}}(\gamma,n)^{64}{\rm{Cu}}$ , ${^{63}{\rm{Cu}}}(\gamma,n)^{62}{\rm{Cu}}$ , ${^{63}{\rm{Cu}}}(\gamma,2n)^{61}{\rm{Cu}}$ , and ${^{63}{\rm{Cu}}}(\gamma,3n)^{60}{\rm{Cu}}$ have been measured within the bremsstrahlung end-point energy $E_{\rm{\gamma max}}$ range of 35–94 MeV. The experiments were performed with the electron beam from the NSC KIPT linear accelerator LUE-40 with the use of the activation and off-line γ-ray spectrometric techniques. Theoretical calculation of the flux-average cross-sections $\langle{\sigma(E_{\rm{\gamma max}})}\rangle_{\rm{th}}$ was conducted using the cross-section $\sigma(E)$ values from the TALYS1.95 code, run with default options. It is shown that the experimental average cross-sections for the reactions ${^{65}{\rm{Cu}}}(\gamma,n)^{64}{\rm{Cu}}$ , ${^{63}{\rm{Cu}}}(\gamma,n)^{62}{\rm{Cu}}$ , and ${^{63}{\rm{Cu}}}(\gamma,2n)^{61}{\rm{Cu}}$ are systematically higher than the theoretical estimates based on the TALYS1.95 code. The obtained $\langle{\sigma(E_{\rm{\gamma max}})}\rangle$ values supplement the data of different laboratories for the $(\gamma,n)$ and $(\gamma,2n)$ reactions of ${^{63}{\rm{Cu}}}$ and ${^{65}{\rm{Cu}}}$ . For the reaction ${^{63}{\rm{Cu}}}(\gamma,3n)^{60}{\rm{Cu}}$ , the values of $\langle{\sigma(E_{\rm{\gamma max}})}\rangle$ were measured for the first time.
The flux-averaged cross-sections
Published:
, doi: 10.1088/1674-1137/ac8652
Abstract:
In this study, we calculate the transition form factors of$ \Lambda_b $ decaying into $ \Lambda_c $ within the framework of light-cone sum rules with the distribution amplitudes (DAs) of the $ \Lambda_b $ -baryon. In the hadronic representation of the correlation function, we isolate both the $ \Lambda_c $ and $ \Lambda_c^* $ states so that the $ \Lambda_b \rightarrow \Lambda_c $ 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 $ \Lambda_b $ in the numerical calculation. We present the numerical predictions for the $ \Lambda_b \rightarrow \Lambda_c $ form factors and branching fractions, averaged forward-backward asymmetry, averaged final hadron polarization, and averaged lepton polarization of the $ \Lambda_b \to \Lambda_c \ell\mu $ decays, as well as the ratio of the branching ratios $ R_{\Lambda_c} $ . The predicted $ R_{\Lambda_c} $ is consistent with LHCb data.
In this study, we calculate the transition form factors of
Published:
, doi: 10.1088/1674-1137/ac80f0
Abstract:
Although$ d^*(2380) $ was first observed by WASA@COSY, its existence has yet to be further confirmed in different types of processes at other facilities. In this work, the possible production of the single dibaryon state $ d^*(2380) $ in the process of $ p{\bar{p}}\to d^*(2380){\bar{p}}{\bar{n}} $ in a future experiment at the $ {\bar{{\rm{P}}}} $ anda facility is estimated. Following the method used in our previous study (Chin. Phys. C 46, 023105), a phenomenological Lagrangian approach is employed to study the single $ {d^*} $ production. Based on the conclusions obtained by the non-relativistic constituent quark model, the cross section of the $ p{\bar{p}}\to d^*(2380){\bar{p}}{\bar{n}} $ reaction via the $ \Delta{\bar{\Delta}} $ intermediate state is estimated, which is in the order of $ nb $ . It is shown that the dominant contribution comes from the diagram with the $ {\bar{\Delta}}{\bar{\Delta}}\to {\bar{p}}{\bar{n}} $ subprocess. However, it is difficult to measure owing to the large background. Further, although the cross section of the diagram with the $ {\bar{d^*}}\to {\bar{p}}{\bar{n}} $ subprocess is small, i.e., only approximately $ 3\%\sim 4\% $ of the total cross section or even smaller, the corresponding number of events is still sufficiently large and can be measured at $ {\bar{{\rm{P}}}} $ anda because the outgoing $ {\bar{p}} $ and $ {\bar{n}} $ come from the same source $ {\bar{d^*}} $ .
Although
Published:
, doi: 10.1088/1674-1137/ac84cb
Abstract:
Recent advances in nuclear theory and new astrophysical observations have led to the need for specific theoretical models applicable to dense-matter physics phenomena. Quantum chromodynamics (QCD) predicts the existence of non-nucleonic degrees of freedom at high densities in neutron-star matter, such as quark matter. Within a confining quark matter model, which consists of homogeneous, neutral 3-flavor interacting quark matter with$ \mathcal{O}(m_s^4) $ corrections, we examine the structure of compact stars composed of a charged perfect fluid in the context of $ f(R,T) $ gravity. The system of differential equations describing the structure of charged compact stars has been derived and numerically solved for a gravity model with $ f(R,T)= R+ 2\beta T $ . For simplicity, we assumed that the charge density is proportional to the energy density, namely, $ \rho_{\rm ch} = \alpha \rho $ . It is demonstrated that the matter-geometry coupling constant β and charge parameter α affect the total gravitational mass and the radius of the star.
Recent advances in nuclear theory and new astrophysical observations have led to the need for specific theoretical models applicable to dense-matter physics phenomena. Quantum chromodynamics (QCD) predicts the existence of non-nucleonic degrees of freedom at high densities in neutron-star matter, such as quark matter. Within a confining quark matter model, which consists of homogeneous, neutral 3-flavor interacting quark matter with
Published:
, doi: 10.1088/1674-1137/ac814d
Abstract:
Considering the quantum electrodynamics (QED) effect, we study the phase transition and Ruppeiner geometry of Euler-Heisenberg anti-de Sitter black holes in the extended phase space. For negative and small positive QED parameters, we observe a small/large black hole phase transition and reentrant phase transition, respectively, whereas a large positive value of the QED parameter ruins the phase transition. Phase diagrams for each case are explicitly shown. Then, we construct the Ruppeiner geometry in thermodynamic parameter space. Different features of the corresponding scalar curvature are shown for both the small/large black hole phase transition and reentrant phase transition cases. Of particular interest is the additional region of positive scalar curvature, indicating a dominant repulsive interaction among black hole microstructures, for the black hole with a small positive QED parameter. Furthermore, universal critical phenomena are observed for the scalar curvature of Ruppeiner geometry. These results indicate that the QED parameter has a crucial influence on the black hole phase transition and microstructure.
Considering the quantum electrodynamics (QED) effect, we study the phase transition and Ruppeiner geometry of Euler-Heisenberg anti-de Sitter black holes in the extended phase space. For negative and small positive QED parameters, we observe a small/large black hole phase transition and reentrant phase transition, respectively, whereas a large positive value of the QED parameter ruins the phase transition. Phase diagrams for each case are explicitly shown. Then, we construct the Ruppeiner geometry in thermodynamic parameter space. Different features of the corresponding scalar curvature are shown for both the small/large black hole phase transition and reentrant phase transition cases. Of particular interest is the additional region of positive scalar curvature, indicating a dominant repulsive interaction among black hole microstructures, for the black hole with a small positive QED parameter. Furthermore, universal critical phenomena are observed for the scalar curvature of Ruppeiner geometry. These results indicate that the QED parameter has a crucial influence on the black hole phase transition and microstructure.
Published:
, doi: 10.1088/1674-1137/ac7f21
Abstract:
Various Higgs factories are proposed to study the Higgs boson precisely and systematically in a model- independent way. In this study, the Particle Flow Network and ParticleNet techniques are used to classify the Higgs decays into multicategories, and the ultimate goal is to realize an "end-to-end" analysis. A Monte Carlo simulation study is performed to demonstrate the feasibility, and the performance looks rather promising. This result could be the basis of a "one-stop" analysis to measure all the branching fractions of the Higgs decays simultaneously.
Various Higgs factories are proposed to study the Higgs boson precisely and systematically in a model- independent way. In this study, the Particle Flow Network and ParticleNet techniques are used to classify the Higgs decays into multicategories, and the ultimate goal is to realize an "end-to-end" analysis. A Monte Carlo simulation study is performed to demonstrate the feasibility, and the performance looks rather promising. This result could be the basis of a "one-stop" analysis to measure all the branching fractions of the Higgs decays simultaneously.
Published:
, doi: 10.1088/1674-1137/ac7fe8
Abstract:
In the present work, we systematically study the α-decay half-lives of uranium (Z=92) isotopes based on the Gamow model with a screened electrostatic barrier. There are only two adjustable parameters in our model i.e. the parameter g and the screening parameter t in the Hulthen potential for considering the screened electrostatic effect of the Coulomb potential. The calculated results are in good agreement with experimental data, and the corresponding root-mean-square (rms) deviations of uranium isotopes with α transition orbital angular momentum l=0 and l=2 are 0.141 and 0.340, respectively. Moreover, we extend this model to predict α-decay half-lives of uranium isotopes whose α decay is energetically allowed or observed but not yet quantified in NUBASE2020. For comparison, the modified Hatsukawa formula (XLZ), the unified Royer formula (DZR), the universal decay law (UDL) and the Viola–Seaborg–Sobiczewski formula (VSS) are also used. The predictions are basically consistent with each other. Meanwhile, the results also indicate that N=126 shell closure is still robust at Z=92 and the spectroscopic factor$ S_{\alpha} $ is almost the same for uranium isotopes with the same l.
In the present work, we systematically study the α-decay half-lives of uranium (Z=92) isotopes based on the Gamow model with a screened electrostatic barrier. There are only two adjustable parameters in our model i.e. the parameter g and the screening parameter t in the Hulthen potential for considering the screened electrostatic effect of the Coulomb potential. The calculated results are in good agreement with experimental data, and the corresponding root-mean-square (rms) deviations of uranium isotopes with α transition orbital angular momentum l=0 and l=2 are 0.141 and 0.340, respectively. Moreover, we extend this model to predict α-decay half-lives of uranium isotopes whose α decay is energetically allowed or observed but not yet quantified in NUBASE2020. For comparison, the modified Hatsukawa formula (XLZ), the unified Royer formula (DZR), the universal decay law (UDL) and the Viola–Seaborg–Sobiczewski formula (VSS) are also used. The predictions are basically consistent with each other. Meanwhile, the results also indicate that N=126 shell closure is still robust at Z=92 and the spectroscopic factor
Published:
, doi: 10.1088/1674-1137/ac82e2
Abstract:
The critical parameters of the liquid-gas phase transition of symmetric nuclear matter are computed using the Brueckner-Hartree-Fock method at finite temperature by employing different realistic nucleon-nucleon potentials. Temperature effects on single-particle potentials, defect functions, and three-body forces are discussed in detail. Results obtained from the full procedure and frozen-correlations approximation are compared. We find critical temperatures of approximately 14 to 19 MeV and critical densities in the range of$ 0.05 $ to $ 0.08{\;\mathrm{fm}^{-3}} $ , depending on the interactions employed.
The critical parameters of the liquid-gas phase transition of symmetric nuclear matter are computed using the Brueckner-Hartree-Fock method at finite temperature by employing different realistic nucleon-nucleon potentials. Temperature effects on single-particle potentials, defect functions, and three-body forces are discussed in detail. Results obtained from the full procedure and frozen-correlations approximation are compared. We find critical temperatures of approximately 14 to 19 MeV and critical densities in the range of
Published:
, doi: 10.1088/1674-1137/ac827c
Abstract:
The isotopic cross sections of residual nuclei produced in fragmentation reactions of 18O projectiles impinging on a carbon target at energies near 260 MeV/nucleon were measured at the HIRFL facility in Lanzhou (China). A full identification of atomic and mass numbers of fragments was achieved from the determination of their magnetic rigidity, energy loss, and time of flight. The production cross sections for a dozen of nitrogen, carbon, and boron isotopes were determined with uncertainties below 30% for most of the cases. The obtained cross sections for N and B isotopes show a rather good agreement with previous experimental data obtained with different projectile energies. The cross sections for some C isotopes seem to exhibit a dependence on the projectile energy. A comparison of the data and several theoretical model calculations are presented.
The isotopic cross sections of residual nuclei produced in fragmentation reactions of 18O projectiles impinging on a carbon target at energies near 260 MeV/nucleon were measured at the HIRFL facility in Lanzhou (China). A full identification of atomic and mass numbers of fragments was achieved from the determination of their magnetic rigidity, energy loss, and time of flight. The production cross sections for a dozen of nitrogen, carbon, and boron isotopes were determined with uncertainties below 30% for most of the cases. The obtained cross sections for N and B isotopes show a rather good agreement with previous experimental data obtained with different projectile energies. The cross sections for some C isotopes seem to exhibit a dependence on the projectile energy. A comparison of the data and several theoretical model calculations are presented.
Published:
, doi: 10.1088/1674-1137/ac8227
Abstract:
The results of experiments on measuring the energy spectra of alpha particles in reactions with heavy ions are presented. The measurements were performed using the high-resolution magnetic analyzer MAVR with beams of 48Ca (280 MeV) and 56Fe (320 and 400 MeV) on 181Ta and 238U targets at an angle of 0°. A strong dependence of the double differential cross sections for production of alpha particles on the atomic number of the target nucleus was observed, which indicates that fast alpha particles are mainly emitted from the target nucleus; this conclusion was also confirmed by calculations within the time-dependent Schrödinger equation approach. An analysis of the obtained experimental data was carried out within the model of moving sources modified to consider the kinematic limits for two-body and three-body exit channels.
The results of experiments on measuring the energy spectra of alpha particles in reactions with heavy ions are presented. The measurements were performed using the high-resolution magnetic analyzer MAVR with beams of 48Ca (280 MeV) and 56Fe (320 and 400 MeV) on 181Ta and 238U targets at an angle of 0°. A strong dependence of the double differential cross sections for production of alpha particles on the atomic number of the target nucleus was observed, which indicates that fast alpha particles are mainly emitted from the target nucleus; this conclusion was also confirmed by calculations within the time-dependent Schrödinger equation approach. An analysis of the obtained experimental data was carried out within the model of moving sources modified to consider the kinematic limits for two-body and three-body exit channels.
Published:
, doi: 10.1088/1674-1137/ac7f22
Abstract:
In this study, we obtain wormhole solutions in the recently proposed extension of symmetric teleparallel gravity, known as$ f(Q,T) $ gravity. Here, the gravitational Lagrangian L is defined by an arbitrary function f of Q and T, where Q is a non-metricity scalar, and T is the trace of the energy-momentum tensor. In this study, we obtain field equations for a static spherically symmetric wormhole metric in the context of general $ f(Q,T) $ gravity. We study the wormhole solutions using (i) a linear equation of state and (ii) an anisotropy relation. We adopt two different forms of $ f(Q,T) $ , (a) linear $ f(Q,T)=\alpha Q+\beta T $ and (b) non-linear $ f(Q,T)=Q+\lambda Q^2+\eta T $ , to investigate these solutions. We investigate various energy conditions to search for preservation and violation among the obtained solutions and find that the null energy condition is violated in both cases of our assumed forms of $ f(Q,T) $ . Finally, we perform a stability analysis using the Tolman-Oppenheimer-Volkov equation.
In this study, we obtain wormhole solutions in the recently proposed extension of symmetric teleparallel gravity, known as
Published:
, doi: 10.1088/1674-1137/ac814e
Abstract:
Previous studies have indicated that the peak of the quarkonium entropy at the deconfinement transition can be related to the entropic force, which would induce the dissociation of heavy quarkonium. In this study, we investigated the entropic force in a rotating hot and dense medium using AdS/CFT correspondence. It was found that the inclusion of angular velocity increases the entropic force, thus enhancing quarkonium dissociation, while chemical potential has the same effect. The results imply that the quarkonium dissociates easier in rotating medium compared with the static case.
Previous studies have indicated that the peak of the quarkonium entropy at the deconfinement transition can be related to the entropic force, which would induce the dissociation of heavy quarkonium. In this study, we investigated the entropic force in a rotating hot and dense medium using AdS/CFT correspondence. It was found that the inclusion of angular velocity increases the entropic force, thus enhancing quarkonium dissociation, while chemical potential has the same effect. The results imply that the quarkonium dissociates easier in rotating medium compared with the static case.
Determination of the half-life of 184gRe and the isomeric ratio of 184m, gRe induced by D-T neutrons
Published:
, doi: 10.1088/1674-1137/ac7f88
Abstract:
The isomeric ratio of 184m, gRe and the half-life of 184gRe were measured in the 185Re (n, 2n) 184Re reaction at 14.8 MeV, and the uncertainty was discussed in detail. The measurements were performed using the activation method implemented for a rhenium sample using the K-400 neutron generator at the Chinese Academy of Engineering Physics (CAEP). Isomeric state and ground state nuclei of 184Re were identified by their γ-ray spectra. To eliminate the effect of the γ-ray emitted from the isomer on the counting of the ground state characteristic peaks, the isomeric ratio of 184m, gRe was calculated to be 0.29 ± 0.11 according to the neutron activation cross-section formula. This result is consistent with previous data within the uncertainty and can be used to determine parameters that characterize the dependence of the level density on the excitation energy and angular momentum. Through exponential function fitting and a detailed discussion of the uncertainty evaluation, the half-life of 184gRe was determined as 35.43 ± 0.16 d, which is consistent with the currently recommended value; however, the uncertainty assessment of the latter was barely documented. In addition, this study indicates that the half-life of the ground state can be obtained by eliminating the contamination of γ-rays emitted from the isomer, which provides the possibility of determining the half-lives of nuclides containing isomers.
The isomeric ratio of 184m, gRe and the half-life of 184gRe were measured in the 185Re (n, 2n) 184Re reaction at 14.8 MeV, and the uncertainty was discussed in detail. The measurements were performed using the activation method implemented for a rhenium sample using the K-400 neutron generator at the Chinese Academy of Engineering Physics (CAEP). Isomeric state and ground state nuclei of 184Re were identified by their γ-ray spectra. To eliminate the effect of the γ-ray emitted from the isomer on the counting of the ground state characteristic peaks, the isomeric ratio of 184m, gRe was calculated to be 0.29 ± 0.11 according to the neutron activation cross-section formula. This result is consistent with previous data within the uncertainty and can be used to determine parameters that characterize the dependence of the level density on the excitation energy and angular momentum. Through exponential function fitting and a detailed discussion of the uncertainty evaluation, the half-life of 184gRe was determined as 35.43 ± 0.16 d, which is consistent with the currently recommended value; however, the uncertainty assessment of the latter was barely documented. In addition, this study indicates that the half-life of the ground state can be obtained by eliminating the contamination of γ-rays emitted from the isomer, which provides the possibility of determining the half-lives of nuclides containing isomers.
Published:
Abstract:
A flavor-dependent kernel is constructed based on the rainbow-ladder truncation of the Dyson-Schwinger and Bethe-Salpeter equation approach of quantum chromodynamics. The quark-antiquark interaction is composed of a flavor-dependent infrared part and a flavor-independent ultraviolet part. Our model gives a successful and unified description of the light, heavy, and heavy-light ground pseudoscalar and vector mesons. For the first time, our model shows that the infrared-enhanced quark-antiquark interaction is stronger and wider for lighter quarks.
A flavor-dependent kernel is constructed based on the rainbow-ladder truncation of the Dyson-Schwinger and Bethe-Salpeter equation approach of quantum chromodynamics. The quark-antiquark interaction is composed of a flavor-dependent infrared part and a flavor-independent ultraviolet part. Our model gives a successful and unified description of the light, heavy, and heavy-light ground pseudoscalar and vector mesons. For the first time, our model shows that the infrared-enhanced quark-antiquark interaction is stronger and wider for lighter quarks.
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