Abstract We present a comprehensive analysis of the recently discovered TeV gamma-ray source, LHAASO J2238+5900. Based on data collected from the LHAASO, our fitting results suggest that the source is significantly extended with an angular extension of 0.54° ± 0.01° and is spatially coincident with the pulsar PSR J2238+5903. Its spectrum is characterized by a power-law with a cutoff at 41.0 ± 3.5 TeV. Additionally, the source exhibits a significant signal of 7.9σ above 100 TeV, implying that it is a PeVatron candidate. While the gamma-ray emission is consistent with a pulsar wind nebula (PWN) scenario, the relatively large extension size also allows for a halo interpretation, potentially caused by electron-positron pairs escaping from the PWN.
Abstract The equation of state of hot and dense strongly interacting quark matter plays a fundamental role in many areas. However, owing to the nonperturbative nature of strong interactions, a reliable treatment is still under debate. We use a symmetry-preserving treatment of a vector\,$\otimes$\,vector contact interaction to study related issues at nonzero temperature or quark chemical potential, and carefully compare a three-momentum cutoff and a proper time regularization scheme. The numerical results show that the character of the phase transition in the present model depends sensitively on the regularization scheme and parameter choices.
Abstract We investigate the discovery potential of a singly produced vector-like top quark $T$ via the $T\to tZ$ decay channel at future muon-proton ($\mu p$) colliders, considering three benchmark center-of-mass energies: $\sqrt{s}=5.29$, $6.48$, and $9.16$~TeV. The baseline signal final state consists of a semileptonic top decay $t\to bW\to b\ell\nu$ and a hadronic $Z\to q\bar{q}$ decay, where the collimated quark pair from the $Z$ boson is reconstructed as a single large-radius fat jet $J$. Full detector-level Monte Carlo simulations are performed for both the signal process and the dominant Standard Model backgrounds. We derive the $5\sigma$ discovery contours and the $95\%$ confidence level exclusion limits in the two-dimensional parameter space spanned by the VLQ mass $m_T$ and the effective coupling $g^*$. A comparison with the $T\to Wb$ channel and with searches at other collider facilities reveals that the $T\to tZ$ decay mode provides complementary sensitivity and offers unique advantages for probing high-mass vector-like $T$ quarks in the boosted jet topology. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Article funded by SCOAP3 and published under licence by Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Science and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd.
Abstract Describing the proton structure function $F_2(x,Q^2)$ across the nonperturbative and transition regimes of quantum chromodynamics remains a significant theoretical challenge. We construct a physics-guided phenomenological representation that combines fermion-resonance and Pomeron-like AdS/QCD basis functions with a neural parametrization. The fermion-resonance sector is constrained by the AdS eigenvalue problem and the physical proton mass, while the neural parametrization describes the effective kinematic mixing, the Pomeron normalization, and a regularized log-space correction. For 187 selected SLAC measurements, a fixed training--test partition containing 153 and 34 points, respectively, gives the point-normalized diagnostics $\chi^2/N_{\rm train}=0.542$, $\chi^2/N_{\rm test}=1.990$, and $\chi^2/N_{\rm all}=0.805$. Conditional on the chosen holographic basis, the fitted channel fractions exhibit a continuous change from Pomeron-like dominance at the lower end of the measured $x$ range to fermion-resonance dominance at larger $x$. The midpoint of the mixing function occurs at $x\simeq0.187$, whereas equality of the final channel fractions occurs at $x\simeq0.226$. These two definitions identify a transition region of approximately $x\simeq0.19$--$0.23$, rather than a unique physical boundary. Although $\alpha_0\simeq1.08$ is compatible with the data, fixed-$\alpha_0$ refits show that it is not separately identifiable from the flexible Pomeron normalization. The $x$-dependent holographic coordinates and associated effective excited scales should therefore be interpreted as basis-dependent effective quantities rather than direct measurements of an $x$-dependent proton spectrum. A comparison with a data-only neural baseline does not establish a predictive advantage for the holographic basis on the present dataset. The resulting framework thus provides a basis-conditioned phenomenological decomposition of the data, rather than a model-independent extraction of the underlying proton dynamics. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Article funded by SCOAP3 and published under licence by Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Science and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd.
Abstract Phenomenological vibrational prescriptions are widely used in microscopic combinatorial nuclear level-density (NLD) calculations, but they introduce empirical phonon-energy systematics that are not generated by the underlying nuclear-structure model. This empirical input limits the predictive consistency of the model, especially for nuclei where low-lying collective spectra are unavailable. To reduce this empirical component, we construct self-consistent phonon inputs for vibrationally corrected combinatorial NLDs by calculating the low-lying \(2_1^+\), \(3_1^-\), and \(4_1^+\) collective modes with the relativistic quasiparticle random-phase approximation (RQRPA) built on the relativistic Hartree--Bogoliubov ground state. These RQRPA phonon energies are used in place of the phenomenological phonon energies, while the intrinsic combinatorial density and the vibrational-coupling prescription are kept unchanged. The method is benchmarked in selected even-even Sn isotopes against the phenomenological prescription and Oslo-normalized level densities. The RQRPA-based calculation approximately preserves the average vibrational enhancement of the phenomenological prescription and gives a level of agreement with the Oslo-normalized data comparable to that of the phenomenological calculation. These results demonstrate, in the selected semi-magic Sn isotopes, that self-consistent microscopic phonon energies can serve as collective inputs for vibrationally corrected combinatorial NLDs without using experimental low-lying spectra as model inputs.
Abstract Signature splitting in the $\nu h_{11/2}$ rotational bands of the odd-$N$, neutron-deficient isotopes $^{117\text{--}127}$Ba is investigated systematically. Band crossings and shape evolution are studied using pairing- and deformation-self-consistent Woods-Saxon-Strutinsky calculations within the total-Routhian-surface (TRS) method in the $(\beta_2,\gamma,\beta_4)$ deformation space. Calculated alignments and deformation-dependent Routhians indicate that proton-pair alignment is favored in $^{117\text{--}123}$Ba, whereas proton and neutron alignments compete in $^{125,127}$Ba. The signature splitting of the lowest $h_{11/2}$ quasineutron Routhians is examined as a function of $\beta_2$ and $\gamma$ both below and above the first band crossing. The observed reduction and occasional inversion of the splitting are interpreted qualitatively in terms of competing $\gamma$-driving tendencies of the strongly coupled odd neutron and the aligned proton pair. For the heavier isotopes, the calculations associate a large splitting with an aligned, oblate $\nu h_{11/2}$ configuration; this association may help to explain why only one member of a partner pair has been identified experimentally at high spin.
Abstract The recent Belle II evidence for $B^+ \to K^+ \nu \bar{\nu}$, combined with a suppressed branching fraction ratio $R \equiv \mathcal{B}(B^0 \to K^{*0} \nu \bar{\nu}) / \mathcal{B}(B^+ \to K^+ \nu \bar{\nu})$, necessitates new physics contributing to both left- and right-handed vector operators. We perform a systematic topological classification of one-loop completions that radiatively generate both operators without tree-level mediation, and construct two minimal benchmark scenarios: a scalar-rich model and a fermion-rich model. Evaluating these frameworks under specific benchmark mass schemes and four distinct flavor structures, we find a generic anti-correlation where enhancing one decay channel typically suppresses the other. A notable exception is a decoupled flavor configuration within the scalar-rich model, which yields simultaneous constructive interference, reducing $R$ by $4.22\%$ while satisfying all complementary flavor bounds. Under a universal coupling assumption, the scalar-rich model yields exact cancellation in the charged mode, highlighting the non-trivial interplay between flavor structure and loop-generated Wilson coefficients. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Article funded by SCOAP3 and published under licence by Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Science and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd.
Abstract Based on events collected with the BESIII detector, the and processes are studied. The is observed in both the and invariant mass spectra, with statistical significances greater than and , respectively. By combining measurements from these processes with those from the previously reported process, the mass and width of the are determined to be and , respectively. In addition, the decay with is observed with a statistical significance exceeding . The properties of the —decay pattern similarities to that of , are consistent with those of a pseudoscalar glueball.
We investigate the QCD corrections to the loop-induced decays of the heavy CP-even Higgs boson, H → Vγ (V = Z, γ), within the framework of the Type-I Two-Higgs-Doublet Model (THDM). Owing to the similarity of the underlying loop topologies, the two decay channels exhibit closely correlated behaviour. After imposing relevant phenomenological constraints, we evaluate the decay widths for 5000 viable parameter points at next-to-leading order (NLO) in QCD under the alignment limit. The H width exceeds that of H→ Zγ by roughly a factor of four. Both are dominated by the top-quark loop: the W contribution vanishes in the alignment limit, and the charged-Higgs loop is suppressed throughout most of the viable parameter region. The corrections exhibit a pronounced dependence on the heavy Higgs boson mass m_H, attaining a maximum in the vicinity of the tt̅ production threshold. To elucidate the individual parameter dependences, dedicated benchmark scenarios are analysed, revealing that the decay widths diminish monotonically with increasing while growing with m_H. The QCD corrections for both decay modes typically span approximately -20% to +20%, with larger corrections in the non-alignment scenario: in the H channel they reach up to +38% at large , and in the H→ Zγ channel they cross zero to become positive. The CP selection rule forces the tt̅ pair into a P-wave configuration at threshold, which strongly suppresses the Coulomb corrections and secures the perturbative stability of the fixed-order prediction. A comparison with ATLAS limits shows that current data do not yet constrain the parameter space, whereas the 𝒪(15%) NLO corrections may become relevant for interpreting exclusion bounds at the HL-LHC.
Abstract In this work, we investigate Lyapunov exponents characterizing the chaotic dynamics of neutral spinning particles around a Kerr black hole, and perform a stringent test of the chaos bound in this framework. A systematic analysis is carried out of the dependence of these exponents on the black hole angular momentum, the particle spin, and its total angular momentum. For a non-extremal Kerr black hole with rotational parameter a = ±0.90, no violation of the chaos bound is observed when the black hole rotational direction is aligned with the z-axis. In the anti-aligned configuration, violations occur only when the spin magnitude or the total angular momentum of the particle exceeds a critical threshold. In the extremal case, which corresponds to a zero-temperature thermal state, the surface gravity vanishes. For the parameter ranges where unstable equilibrium orbits exist, the exponents are found to be positive. These results provide clear evidence for the violation of the bound by a spinning particle in Kerr spacetime.
Abstract {\color{blue} We are intended to evaluate the complexity of self-gravitational matter composition having anisotropic pressure and the electric field.} The modified field equations associated with the $f(R, G)$ gravity having the effect of electric charge and the expressions for the mass function are derived, where {\color{blue} $R$ is Ricci scalar and $G$ represents the Gauss-Bonnet invariant.} The concept of complexity suggested by Herrera and his collaborators in 2018 which is further elaborated within the context of a charged cylindrically symmetric system after considering the framework of $f(R, G)$ theory and carrying out a comprehensive evaluation on the orthogonal splitting of the Riemann curvature tensor. Among the derived scalars $Y_{TF}$ is referred as the complexity factor, that includes the impacts of specific intrinsic features of the fluid, such as variations in energy density, anisotropic pressure, and the electric charge. Furthermore, the results obtained in the presence of additional curvature terms corresponding to $f(R, G)$ gravity are studied through the establishment of a relationship between Tolman mass, Weyl scalar, and the complexity factor. This analysis is relevant from a astrophysical perspective, since compact stellar interiors are expected to involve dense matter, pressure anisotropy, electromagnetic effects and strong-field relativistic corrections, while in this context, the complexity factor \(Y_{TF}\) provides a geometric diagnostic for measuring how density inhomogeneity, local anisotropy, charge distribution and modified Gauss-Bonnet corrections influence the internal organization and stability of neutron-star-like compact configurations. The consideration of polytropic equation of state further connects the proposed scenario with effective modeling of dense compact-star matter.
Abstract We present a lattice QCD spectroscopy study of the conjectured H-dibaryon for five channels at nine temperatures ranging from $T/T_c =0.24$ to $T/T_c = 1.90$. The five channels are flavor singlet, flavor 27-plet, $\Lambda \Lambda$, $N \Xi$, and $\Sigma \Sigma$. Five interpolating operators are employed, one for each channel. The simulations are performed on anisotropic lattices with $N_f=2+1$ flavours of clover fermions at a quark mass which corresponds to $m_\pi=384(4)\, {\rm MeV} $. The thermal ensembles were provided by the FASTSUM collaboration and the zero-temperature ensembles by the Hadspec collaboration. The simulations show that the H-dibaryon mass in the 27-plet channel is the largest at the nine temperatures, while the mass in the $\Sigma \Sigma $ channel is the lightest. We also calculate the spectral density of the correlation function of H-dibaryon for the five channels. The spectral density distributions of the five channels exhibit similar behavior. The mass differences $\Delta m = m_H - 2\,m_{\Lambda} $ of H-dibaryon and $\Lambda$ pair at $T/T_c =0.24 $ for the five channels are also estimated. The results show that $\Delta m $ is positive for the 27-plet and $\Lambda \Lambda$ channels, while $\Delta m $ is negative for the singlet, $N \Xi$ and $\Sigma \Sigma$ channels. These findings are limited, however, by the use of a single spatial volume and a relatively large quark mass. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Article funded by SCOAP3 and published under licence by Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Science and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd.
Abstract We investigate the transverse momentum broadening~(TMB) of particle production in upcoming electron–ion collision experiments, an important manifestation of jet transport in cold nuclear matter. By considering the effects of parton multiple scattering in nuclear medium within the high-twist expansion framework in perturbative QCD, we calculate the TMB of single hadron production in semi-inclusive measurements, as well as the nuclear enhancement of the transverse momentum imbalance for di-hadron and heavy-meson pair productions. A central input to our calculations is the effective jet transport coefficient $\hat{q} = \hat{q}(x,Q^2)$, which depends on the parton momentum fraction $x$ and the probing scale $Q^2$. This quantity is obtained from an improved global analysis of existing data, with uncertainties quantified using the Hessian method. Our predictions show a clear kinematic and color‑state dependence of the nuclear‑induced broadening and imbalance. These results demonstrate that future measurements of TMB will provide valuable insights into the kinematic dependence of jet transport properties, thereby substantially advancing the jet tomography of cold nuclear matter.
Abstract Starting from the first law of black hole thermodynamics, we establish an explicit correspondence between the corrected entropy and the metric function under the condition of fixed black hole energy and horizon position. Using the corrected metric, we further compute the photon sphere radius and shadow size, demonstrating that different entropy corrections lead to characteristic optical shifts. By comparing with the Event Horizon Telescope observations of Sgr A*, we constrain the parameter range introduced in the corrected entropy. This provides a feasible approach for testing generalized entropy frameworks and probing deviations from the Bekenstein-Hawking area law.
Abstract We present a joint factorization and resummation study of the energy-energy correlator (EEC) and thrust in $e^+e^-$ collisions. Analyzing the joint kinematic distribution reveals five relevant regimes that dictate how the global event shape restricts local energy correlations. In the collinear limit ($z \to 0$), we show that the global thrust boundary strongly constrains the jet substructure, requiring a sub-jet refactorization. In the back-to-back limit ($z \to 1$), the coexistence of $\mathrm{SCET}_{\mathrm{I}}$ and $\mathrm{SCET}_{\mathrm{II}}$ soft scales demands the $\mathrm{SCET}_{+}$ framework. We derive the factorization theorems for all five regimes and calculate the corresponding differential jet functions at one-loop order. By cleanly separating the overlapping soft and collinear modes, our framework provides a systematic factorization description of the EEC under global thrust constraints in the singular limits.
Abstract We report a systematic generator-level study of identified-hadron production in minimum-bias Au+Au collisions at √sN N = 6, 7, and 8 GeV using EPOS-LHC, EPOS-4, and SMASH. These frameworks represent different microscopic descriptions, ranging from string/core-corona and hydrodynamic dynamics to purely hadronic transport. We compare rapidity distributions, transverse-momentum spectra, two-dimensional pT − y density maps, particle-yield ratios, and number-of-constituent-quark-scaled elliptic flow. Charged and neutral pions provide a relatively model-insensitive baseline associated mainly with bulk production and resonance feed-down, whereas K±, protons, and Λ baryons exhibit stronger model dependence. The pT − y maps identify the longitudinal and transverse phase-space regions in which the model predictions separate, although conclusions for rare strange particles are restricted to statistically populated regions. Elliptic flow is presented as v2/nq versus transverse kinetic energy per constituent quark, (mT −m0)/nq . All three models show an approximate common trend at low and intermediate transverse kinetic energy, with the closest visual grouping in EPOS-LHC; deviations and statistical uncertainties increase at larger (mT − m0)/nq. Because each sample contains 50,000 events, no quantitative conclusions are drawn from sparsely populated forward-rapidity or high-pT regions. The results provide exploratory model baselines and identify strange-particle spectra, K−/K+, Λ/π+, double-differential pT − y measurements, and identified-particle elliptic flow as priority observables in the NICA energy range. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Article funded by SCOAP3 and published under licence by Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Science and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd.
Based on the fractional entropy from fractional quantum mechanics, fractional holographic dark energy (FHDE) has been proposed with the Hubble horizon as the IR cutoff (FHDEH). We extend this framework by adopting the future event horizon and the particle horizon as the IR cutoff, proposing the FHDEF and FHDEP models. Using the SN+OHD+DESI DR2 dataset to constrain these models, we find that all three models provide a marginally lower χ^2_min compared to ΛCDM but without significant preference according to AIC and BIC. When CMB distance priors are included, the FHDEH and FHDEP models are strongly ruled out. We further analyze the cosmological evolution for these models, and find that only the FHDEF model predicts nearly identical evolutions of Ω_m and Ω_de to those of the ΛCDM model across cosmic history, but its deceleration parameter q deviate from the ΛCDM model in the future, indicating richer late time dynamics beyond the standard ΛCDM cosmology.
This work examines the observational signatures of rotating black holes with tidal charge in the Randall–Sundrum braneworld scenario. Combining an elliptic-integral-based analytical treatment with numerical ray tracing, we characterize photon motion around braneworld black holes in detail. For small observer inclinations, secondary images remain embedded inside the primary emission rings. As the inclination becomes larger, the primary and secondary images gradually separate and produce a strongly asymmetric image morphology. We show that the image asymmetry and the deformation of the inner shadow are jointly controlled by the black hole spin, the tidal charge, and the observer inclination. To analyze the frequency shifts across the accretion disk, we extend the emitting region from the ISCO down to the event horizon by including the plunging flow. The results indicate that the observer inclination is the dominant factor governing the frequency-shift distribution. In addition, we reconstruct braneworld black hole images using a fisheye-lens ray-tracing model. The optical morphology and brightness distribution show a clear dependence on the observing frequency, especially when comparing 230 GHz with 86 GHz. We also contrast the brightness distributions of prograde and retrograde disks, finding that both the total intensity and the peak intensity at 86 GHz are higher than those at 230 GHz. For negative values of the tidal charge, we further investigate the corresponding frequency-shift behavior and 230 GHz intensity profiles, which may provide useful theoretical guidance for future studies of extra-dimensional gravity models.
Abstract Experiments with 48 Ca and 54 Cr induced reactions were performed at the gas-filled recoil separator named Spectrometer for Heavy Atoms and Nuclear Structure-2 (SHANS2) of the China Accelerator Facility for superheavy Elements (CAFE2). The isotopic distributions of nuclei produced in the reactions of 48 Ca+ 243 Am, 54 Cr+ 243 Am, and 54 Cr+ 238 U were investigated. Bombardments were conducted at energies near the respective Coulomb barriers, with the SHANS2 magnetic rigidities set to collect fusion-evaporation residues. α -decay spectroscopy was employed to identify products, revealing 58 different isotopes in these experiments. The analysis indicates that the distribution of nuclides produced in different reactions exhibits clear systematic trends. Based on their mass distributions, these nuclei were attributed to the products from the quasi-fission (QF) process. Additionally, several short-lived fission events were identified and attributed to the fission isomers near the target.
Since the Event Horizon Telescope (EHT) collaboration released horizon-scale images of the supermassive black holes Sgr A* and M87*, a new observational window for probing black hole spacetimes in the strong-gravity regime has opened. As an important class of Kerr black hole mimickers, rotating Simpson-Visser (SV) black holes exhibit a degeneracy with Kerr black holes in terms of shadow size, making them difficult to distinguish using shadow observations alone. Motivated by this issue, we present a systematic investigation of the radiative properties and optical appearance of rotating SV black holes surrounded by a thin accretion disk, focusing on the influence of the regularization parameter g on the relevant observables. The results show that although the kinematic quantities and the location of the innermost stable circular orbit (ISCO) depend on the regularization parameter g, the radiative efficiency of the rotating SV black hole is the same as that of its Kerr counterpart. Within the Novikov-Thorne thin-disk model, we study the radiative flux, effective temperature, and spectral luminosity; adopting observational parameters relevant to Sgr A* and M87*, we compute concrete examples for rotating SV black holes and compare them with those for Kerr black holes. The results show that the parameter g suppresses the maximum values of these quantities. In addition, using a backward ray-tracing technique, we numerically simulate the optical appearance of rotating SV black holes and analyze the corresponding intensity images, redshift, and observed flux distributions. Our results indicate that these quantities are sensitive to g. In particular, as g increases, the observed intensity is significantly suppressed, and the photon ring region exhibits a remarkable increase in width. Our findings suggest that accretion-disk-related observables may provide important avenues to distinguish between rotating SV black holes and Kerr black holes, and offer theoretical guidance for future high-resolution observations.
