Lanzhou Center for Theoretical Physics
We constrain the parameter space of Bumblebee model within a cosmological background and investigate the properties of gravitational waves under the constrained parameter set. Specifically, we derive the conditions for the absence of ghost, Laplacian, and Tachyon instabilities for perturbations in a cosmological background. By incorporating the observed accelerated expansion of the universe and the observational constraints on tensor gravitational waves, we derive bounds on the parameter space of Bumblebee model. We then examine the polarization modes, propagation speeds, and amplitude relations of gravitational waves within this constrained framework. Our results indicate that the non-minimal coupling parameter ξ\xi must be non-positive, and the lower bound on the Lorentz-violating parameter ξb2\xi b^2 is constrained to be on the order of 101510^{-15}. Gravitational waves in Bumblebee model are found to propagate in two tensor modes, two vector modes, and one mixed scalar mode. Notably, the tensor gravitational waves travel at subluminal speeds, whereas the vector and scalar gravitational waves propagate at superluminal speeds. These results provide a concrete theoretical framework and specific observational signatures for testing Lorentz invariance in the gravitational sector with future gravitational-wave detectors.
Environmental feedback mechanisms are ubiquitous in real-world complex systems. In this study, we incorporate a homogeneous environment into the evolutionary dynamics of a three-state system comprising cooperators, defectors, and empty nodes. Both coherence resonance and equilibrium states, resulting from the tightly clustering of cooperator agglomerates, enhance population survival and environmental quality. The resonance phenomenon arises at the transition between cooperative and defective payoff parameters in the prisoner's dilemma game.
This work aims to understand how quantum mechanics affects heat transport at low temperatures. In the classical setting, by considering a simple paradigmatic model, our simulations reveal the emergence of Negative Differential Thermal Resistance (NDTR): paradoxically, increasing the temperature bias by lowering the cold bath temperature reduces the steady-state heat current. In sharp contrast, the quantum version of the model, treated via a Lindblad master equation, exhibits no NDTR: the heat current increases monotonically with thermal bias. This marked divergence highlights the fundamental role of quantum effects in low-temperature thermal transport and underscores the need to reconsider classical predictions when designing and optimizing nanoscale thermal devices.
In a generalized parameter space, regular black holes can be regarded as non-singular solutions under specific parameters in Einstein gravity theory coupled with non-linear electromagnetic fields. Following this concept, we investigate the thermodynamic states and phase transitions of Bardeen-AdS-class black holes, revealing that the system can be classified into two categories, Type I and Type II, based on whether it adopts a pure Bardeen-AdS spacetime without event horizons or a Bardeen-AdS black hole as its phase state, each exhibiting distinct thermodynamic properties. If one includes the Bardeen-AdS black holes in the system (Type I), there will be three distinct black hole states and the phase transitions between them are analogous to the Reissner-Nordstrom-AdS black holes. On the other hand, if the pure Bardeen-AdS spacetime is included (Type II), an additional tiny black hole state emerges. A phase transition reminiscent of the Hawking-Page transition was found. Significantly, in this scenario, thermodynamical characteristic curves exhibit discontinuous behavior, which attributes to the multiple horizons. The presence of a Bardeen-AdS black hole within the phase structure of the Bardeen-AdS-class black hole profoundly modifies the thermodynamical properties of the system, highlighting the novel aspects of regular black holes.
We report on an experimental investigation of the transition of a quantum system with integrable classical dynamics to one with violated time-reversal (T) invariance and chaotic classical counterpart. High-precision experiments are performed with a flat superconducting microwave resonator with circular shape in which T-invariance violation and chaoticity are induced by magnetizing a ferrite disk placed at its center, which above the cutoff frequency of the first transverse-electric mode acts as a random potential. We determine a complete sequence of approx. 1000 eigenfrequencies and find good agreement with analytical predictions for the spectral properties of the Rosenzweig-Porter (RP) model, which interpolates between Poisson statistics expected for typical integrable systems and Gaussian unitary ensemble statistics predicted for chaotic systems with violated T invariance. Furthermore, we combine the RP model and the Heidelberg approach for quantum-chaotic scattering to construct a random-matrix model for the scattering (S) matrix of the corresponding open quantum system and show that it perfectly reproduces the fluctuation properties of the measured S matrix of the microwave resonator.
Inspired by the recent discovery of an pseudoscalar enhancement structure near the ttˉt\bar{t} threshold reported by the CMS and ATLAS collaborations, this work investigates the mass spectra of single topped hadrons-including both topped mesons and topped baryons-based on a relativistic potential model. Our results show that, using the same parameters obtained from the fit to mesons and baryons, the calculated mass of pseudoscalar topponium is in excellent agreement with the observed enhancement structure, demonstrating the consistency and unifying power of the model. Accordingly, we provide predictions for the mass spectra of ground and low-lying orbitally excited single topped mesons and baryons, which may serve as a reference for future experimental searches for these possible new hadronic matter.
This work aims to understand how quantum mechanics affects heat transport at low temperatures. In the classical setting, by considering a simple paradigmatic model, our simulations reveal the emergence of Negative Differential Thermal Resistance (NDTR): paradoxically, increasing the temperature bias by lowering the cold bath temperature reduces the steady-state heat current. In sharp contrast, the quantum version of the model, treated via a Lindblad master equation, exhibits no NDTR: the heat current increases monotonically with thermal bias. This marked divergence highlights the fundamental role of quantum effects in low-temperature thermal transport and underscores the need to reconsider classical predictions when designing and optimizing nanoscale thermal devices.
As a key component of quantum networks, quantum router distributes quantum information among different quantum nodes. Silicon-vacancy (SiV) center in diamond offers a promising platform for quantum technology due to its strong strain-induced coupling with phonons. However, the development of practical quantum router faces challenges of achieving long-range entanglement and suppressing decoherence. Here, we propose a non-Markovian quantum router based on a diamond waveguide embedded with an array of SiV centers as the quantum nodes. Unlike conventional channel-switching methods, our design enables parallel quantum-state transfer from a single input node to multiple target nodes, analogous to a classical WiFi router. We demonstrate that persistent entanglement and suppressed decoherence of the SiV centers over long distances are achievable when bound states are present in the energy spectrum of the total system formed by the SiV centers and the phonon waveguide. Our scheme enriches the implementation of quantum routing and prompts the development of solid-state quantum networks.
This study explores the ground-state phase diagram and topological properties of the spinless 1D Su-Schrieffer-Heeger (SSH) model with nearest-neighbor (NN) interactions at quarter filling. We analyze key physical quantities such as the local electron density distribution, correlation functions for bond-order-wave (BOW) and charge-density-wave (CDW) -- by integrating twisted boundary conditions with the Lanczos technique and employing high-precision numerical diagonalization methods, complemented by a mean-field approximation (MFA) based on bond-order and charge-density modulation analysis. This approach enables precise identification of phase transition critical points. Our results indicate that the system exhibits a topologically trivial band insulating (BI) phase for strong attractive interactions, with its upper boundary forming a downward-opening curve peaking at V/t2.3V/t\simeq-2.3 and extending to V/t2.6V/t\simeq-2.6. Within 2.6V/t0.5-2.6 \leq V/t \leq -0.5, a BOW phase emerges for δt/t>0.45\left|\delta t/t\right| > 0.45, with its boundaries converging as δt/t\left|\delta t/t\right| decreases, terminating at a single point at δt/t0.45\left|\delta t/t\right|\simeq0.45. In other parameter regions, a CDW phase is realized. Through this analysis, we elucidate the topological properties of the interacting spinless SSH model at quarter filling, highlighting the competition among CDW, BOW, and BI phases. By tuning VV and δt\delta t, the system exhibits diverse correlated phenomena, offering new insights into one-dimensional quantum phase transitions and the interplay between topology and order.
Motivated by the recent observation of the open-charm tetraquark Tcsˉ0a(2327)T_{c\bar{s}0}^{a}(2327) by the LHCb Collaboration, as well as results from Lattice QCD calculations, we consider the Tcsˉ0a(2327)T_{c\bar{s}0}^{a}(2327) and the Ds0(2317)D_{s0}^{*}(2317) as DKDK molecular states, with I(JP)I(J^{P}) equal to 1(0+)1(0^{+}) and 0(0+)0(0^{+}), respectively, and we investigate their strong decay behavior in an effective Lagrangian approach. Within the model parameter range, we can reproduce the Tcsˉ0a(2327)T_{c\bar{s}0}^{a}(2327) experimental decay width, with the assumption that the Ds+π0D_{s}^{+}\pi^{0} is the dominant decay channel of the Tcsˉ0a+(2327)T_{c\bar{s}0}^{a+}(2327). In the same parameter range, we can establish a stringent limitation for the decay width of the Ds0(2317)D_{s0}^{*}(2317), which is (63.0209) keV(63.0-209)~\mathrm{keV} being significantly smaller than the PDG upper limit value.
We embark on a systematical analysis of the quark and gluon gravitational form factors (GFFs) of the proton, by connecting energy-momentum tensor (EMT) and the near-threshold vector meson photoproduction (NTVMP). Concretely, the quark contributions of GFFs are determined by global fitting the cross section of the lightest vector meson ρ0\rho^0 photoproduction. Combined with the gluon GFFs achieved from heavy quarkonium J/ψJ/\psi photoproduction data, the complete GFFs are obtained and compared with the experimental results and Lattice QCD determinations. In addition, we use the Resonances Via Padé (RVP) method based on the Schlessinger Point Method (SPM) to obtain a model-independent quark DD-term distribution by direct analytical continuation of Deep Virtual Compton Scattering (DVCS) experimental data. If errors are considered, the results obtained by RVP are basically consistent with those obtained by NTVMP. Moreover, the comprehensive information on GFFs helps us to uncover the mass distribution and mechanical properties inside the proton. This work is not only an important basis for delving the proton enigmatic properties, unraveling the secrets of the proton internal nature but also have significance theoretical guiding for future JLab and EICs experimental measurements.
Whole-brain models offer a promising method of predicting seizure spread, which is critical for successful surgery treatment of focal epilepsy. Existing methods are largely based on structural connectome, which ignores the effects of heterogeneity in regional excitability of brains. In this study, we used a whole-brain model to show that heterogeneity in nodal excitability had a significant impact on seizure propagation in the networks, and compromised the prediction accuracy with structural connections. We then addressed this problem with an algorithm based on random walk with restart on graphs. We demonstrated that by establishing a relationship between the restarting probability and the excitability for each node, this algorithm could significantly improve the seizure spread prediction accuracy in heterogeneous networks, and was more robust against the extent of heterogeneity. We also strategized surgical seizure control as a process to identify and remove the key nodes (connections) responsible for the early spread of seizures from the focal region. Compared to strategies based on structural connections, virtual surgery with a strategy based on mRWER generated outcomes with a high success rate while maintaining low damage to the brain by removing fewer anatomical connections. These findings may have potential applications in developing personalized surgery strategies for epilepsy.
The Kitaev magnets with bond-dependent interactions have garnered considerable attention in recent years for their ability to harbor exotic phases and nontrivial excitations. The topological magnons, which are indicated by nonzero Chern number that can enhance the thermal Hall conductivity, are proposed to partially explain thermal Hall measurements in real materials. Hitherto, topological magnons have been extensively explored when the magnetic field is normal to the honeycomb plane, but their topological characteristics are less studied in the presence of in-plane magnetic field. Here, we study two distinct in-plane field induced spin-flop phases in the Γ\Gamma-Γ\Gamma' model, both of which are off-diagonal couplings that have intimate relation to the Kitaev interaction. The two spin-flop phases are distinguished by their out-of-plane spin components which can be either antiparallel or parallel, thus dubbing antiferromagnetic (AFM) or ferromagnetic (FM) spin-flop phases, respectively. We map out topological phase diagrams for both phases, revealing a rich pattern of the Chern number over exchange parameters and magnetic field. We analytically calculate the boundaries of topological phase transitions when the magnetic field is along the aa and bb directions. We find that the thermal Hall conductivity and its derivative display contrasting behaviors when crossing different topological phase transitions. The striking difference of the two phases lies in that when the magnetic field is along the bb direction, topological magnons are totally absent in the AFM spin-flop phase, while they can survive in the FM analogue in certain parameter regions.
Motivated by the non-Fermi liquid (NFL) phase in solvable Hatsugai-Kohmoto (HK) model and ubiquitous quantum oscillation (QO) phenomena observed in strongly correlated electron systems, e.g. cuprate high-Tc superconductor and topological Kondo insulator SmB6_{6}, we have studied the QO in HK model in terms of a combination of analytical and numerical calculation. In the continuum limit, the analytical results indicate the existence of QO in NFL state and its properties can be described by Lifshitz-Kosevich-like formula. Furthermore, numerical calculations with Luttinger's approximation on magnetic-field-dependent density of state, magnetization and particle's density agree with the findings of analytical treatment. Although numerical simulation from exact diagonalization exhibits certain oscillation behavior, it is hard to extract its oscillation period and amplitude. Therefore, more work (particularly the large-scale numerical simulation) on this interesting issue is highly desirable and we expect the current study on HK model will be helpful to understand generic QO in correlated electron materials.
The Kitaev-type spin chains have been demonstrated to be fertile playgrounds in which exotic phases and unconventional phase transitions are ready to appear. In this work, we use the density-matrix renormalization group method to study the quantum phase diagram of a spin-1 Kitaev chain with a tunable negative single-ion anisotropy (SIA). When the strength of the SIA is small, the ground state is revealed to be a spin-nematic phase which escapes conventional magnetic order but is characterized by a finite spin-nematic correlation because of the breaking spin-rotational symmetry. As the SIA increases, the spin-nematic phase is taken over by either a dimerized phase or an antiferromagnetic phase through an Ising-type phase transition, depending on the direction of the easy axis. For large enough SIA, the dimerized phase and the antiferromagnetic phase undergo a ``Landau-forbidden" continuous phase transition, suggesting new platform of deconfined quantum critical point in spin-1 Kitaev chain.
For a distorted black hole (BH), its ringdown waveform is a superposition of quasi-normal modes (QNMs). In general relativity (GR), the lower order QNM frequencies and damping rates can be well approximated by a polynomial of BH's dimensionless spin and overall scaled by BH's mass. That is to say, we can test the no-hair theorem of BH in GR model-independently by allowing not only an overall fractional deviation (as M. Isi {\it et al.} did) but also a set of fractional deviation for every coefficient. In the paper, we will apply the latter method to retest the no-hair theorem with GW150914 and probe hairs' behaviors if hairs exist. Eventually, we find the data favors GR.
This poster presents recent experimental findings from the BESIII experiment, including two categories of studies. Firstly, it reports the studies on the hyperon pair production in the processes e+eΛΛˉe^+e^- \to \Lambda\bar\Lambda, Σ+Σˉ\Sigma^+\bar\Sigma^-, Σ0Σˉ0\Sigma^0\bar\Sigma^0, Ξ0Ξˉ0\Xi^0\bar\Xi^0 and ΞΞˉ+\Xi^-\bar\Xi^+. The Born cross sections for these processes are measured at center-of-mass energies ranging from 3.53.5 to 4.94.9 GeV. For the first time, evidence for the decays ψ(3770)ΛΛˉ\psi(3770)\to\Lambda\bar\Lambda and ΞΞˉ+\Xi^-\bar\Xi^+ is found. Secondly, it reports the measurements of the Born cross sections of multi-body decays involving hyperon final states. The evidence of ψ(4160)KΞˉ+Λ+c.c.\psi(4160)\to K^-\bar\Xi^+\Lambda+c.c. is found. These results offer new perspectives on hyperon production in e+ee^+e^- annihilation and the decay mechanism of vector charmonium(-like) states, contributing to our understanding of hadron dynamics.
In this paper, we study the circular orbit of the spinning test particle in the background of a rotating boson star. Using the pole-dipole approximation and neglecting the back-reaction of the spinning test particle on the spacetime, the equation of motion of the spinning test particle is described by the Mathisson-Papapetrou-Dixon equation. We solve this equation under the Tulczyjew spin-supplementary condition and obtain the four-momentum and four-velocity of the spinning test particle. Quite different from the spinless particle, the effective potential of the spinning particle with zero orbital angular momentum goes to infinite at the center of the rotating boson star. This will lead to the fact that the spinning particle can not pass through the center of the boson star. However, when the spin angular momentum and orbital angular momentum satisfy 2sˉ+lˉ=02\bar{s}+\bar{l}=0, the effective potential is not divergent anymore and the spinning particle can pass through the center of the rotating boson star. {We still investigate how the spin affects the structure of the circular orbits and we find that the spin will induce the larger or smaller regions of no circular orbits, unstable circular orbits, and stable circular orbits.} Moreover, the radius and energy of the circular orbit will be decreased or increased by the particle spin. These results will have an important application in testing the gravitational waves in the boson star background.
Despite of simplicity of the transverse antiferromagnetic Ising model with a uniform longitudinal field, its phases and involved quntum phase transitions (QPTs) are nontrivial in comparison to its ferromagnetic counterpart. For example, what is the nature of the mixed-order in such a model and does there exist a disorder phase? Here we use a pattern picture to explore the competitions between the antiferromagnetic Ising interaction, the transverse and longitudinal fields and uncover what kind of pattern takes responsibility of these three competing energy scales, thus determine the possible phases and their QPTs or crossovers. Our results not only unveil rich physics of this paradigmatic model, but also further stimulate quantum simulation by using current available experimental platforms.
The discoveries of the PψsΛ(4459)P_{\psi s}^\Lambda(4459) and $P_{\psi s}^\Lambda(4338)asthepotential as the potential \Xi_c\bar D^{(*)}$ molecules have sparked our curiosity in exploring a novel class of molecular $P_{\psi s}^{\Lambda/\Sigma}$ pentaquarks. In this study, we carry out an investigation into the higher molecular pentaquarks, specifically focusing on the $P_{\psi s}^{\Lambda/\Sigma}statesarisingfromthe states arising from the \Xi_c^{(\prime,*)}\bar D_1/\Xi_c^{(\prime,*)}\bar D_2^*$ interactions. Our approach employs the one-boson-exchange model, incorporating both the SS-DD wave mixing effect and the coupled channel effect. Our numerical results suggest that the $\Xi_c\bar D_1stateswith states with I(J^P)=0({1}/{2}^+,\,{3}/{2}^+),the, the \Xi_c\bar D_2^*$ states with I(JP)=0(3/2+,5/2+)I(J^P)=0({3}/{2}^+,\,{5}/{2}^+), the ΞcDˉ1\Xi_c^{\prime}\bar D_1 states with I(JP)=0(1/2+,3/2+)I(J^P)=0({1}/{2}^+,\,{3}/{2}^+), the ΞcDˉ2\Xi_c^{\prime}\bar D_2^* states with I(JP)=0(3/2+,5/2+)I(J^P)=0({3}/{2}^+,\,{5}/{2}^+), the ΞcDˉ1\Xi_c^{*}\bar D_1 states with I(JP)=0(1/2+,3/2+,5/2+)I(J^P)=0({1}/{2}^+,\,{3}/{2}^+,\,{5}/{2}^+), and the $\Xi_c^{*}\bar D_2^*stateswith states with I(J^P)=0({1}/{2}^+,\,{3}/{2}^+,\,{5}/{2}^+,\,{7}/{2}^+)$ can be recommended as the most promising molecular PψsΛP_{\psi s}^\Lambda pentaquark candidates, and there may exist the potential molecular $P_{\psi s}^\Sigmapentaquarkcandidatesforseveralisovector pentaquark candidates for several isovector \Xi_c^{(\prime,*)}\bar D_1/\Xi_c^{(\prime,*)}\bar D_2^*$ states. With the higher statistical data accumulation at the LHCb's Run II and Run III status, there is the possibility that our predicted PψsΛ/ΣP_{\psi s}^{\Lambda/\Sigma} states can be detected through the weak decay of the Ξb\Xi_b baryon, especially in hunting for the predicted PψsΛP_{\psi s}^\Lambda states.
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