Abstract We investigate how lattice distortions reshape the magnetic correlations and muon-spin relaxation (μSR) response of the frustrated pyrochlore Nd2Ru2O7. Because implanted muons occupy minima of the electrostatic potential, temperature-dependent modifications of the RuO6 network alter both the muon stopping-site landscape and the quasistatic internal fields sensed by the muons. To capture this magneto-structural coupling, we develop a mixed static–dynamic depolarization framework in which an ordered internal field is convoluted with an exponential random field associated with domain-wall or cluster-like magnetic textures and averaged over a Lorentzian distribution representing structural inhomogeneity, while a phenomenological exponential term describes dynamic Ru-moment fluctuations. Simulations further show that, within the strong-collision scheme, the dynamical narrowing effect depends sensitively on the degree of static disorder and can disappear completely for sufficiently broad random-field distributions. The model demonstrates that broad quasistatic disorder can strongly suppress oscillatory and Kubo–Toyabe-like features, producing relaxation spectra often attributed solely to rapid spin dynamics. Application to zero-field- and longitudinal-field-μSR spectra reveals anomalies near 145, 31, and 21 K associated with spatially inhomogeneous antiferromagnetic correlations and low-temperature magnetic restructuring. Although LF measurements under 3850 G show predominantly dynamic long-time relaxation, a residual short-time relaxation below $t\sim 1$–$2~\mu$s indicates surviving quasistatic magnetic regions consistent with cluster-like spin-glass behavior stabilized by structural disorder.
Abstract A generalized theory of beam impedance for ceramic breaks has been developed by introducing two types of effective impedance that account for accelerator environments and the capacitors attached to the ceramic break. For a ceramic break with a titanium nitride (TiN) coating installed in an accelerator, the setup conditions are characterized by the effective impedance determined from scattering matrices, for which a theoretical basis is also provided to calibrate the beam-induced voltage on the ceramic break. Using the calibration scheme, the beam distribution with high-frequency components can be recovered from the beam-induced voltage modulated by the surrounding conditions. For a TiN-coated ceramic break covered by capacitors-whose direct numerical simulation requires an excessively fine mesh-the capacitor effect is incorporated by the other effective impedance. For the radiation fields, analytical results for a floated ceramic break in an open space can be obtained independently of capacitors or TiN coating. A benchmark test between analytical results and simulations is conducted using a ceramic break with neither TiN coating nor capacitors to cement the foundation of the theory.
Abstract Analyzing the post-merger phase of gravitational waves from observed binary neutron star coalescences is expected to provide constraints on the neutron star equation of state (EOS), which remains theoretically uncertain. Achieving this objective requires a method capable of simultaneously attaining high temporal and frequency resolutions at a local level. The Hilbert–Huang transform (HHT) has been proposed as a suitable approach for this purpose. Previous studies demonstrated that replacing the conventional cubic spline interpolation of extrema in the HHT with the Akima spline suppresses interpolation-induced overshoot and improves analytical accuracy. In this study, we investigate whether the accuracy can be further improved by employing the Steffen interpolation, an interpolation scheme that inherently prevents overshoot. The results confirm that the HHT implemented with the Steffen interpolation achieves the highest performance.
Abstract The gauge theory bootstrap computes the strongly coupled pion dynamics by considering the most general scattering matrix, form factors, and spectral densities and matching them with perturbative QCD at high energy and with weakly coupled pions at low energy. In this work, we show that further constraints on the spectral densities significantly reduce the possible solutions to a small set of qualitatively similar ones. Quantitatively, the precise solution is controlled by the asymptotic value of the form factors and Shifman–Vainshtein–Zakharov sum rules. We also introduce an iterative procedure that, starting from a generic feasible point, converges to a unique solution parameterized by the UV input. For the converged solution we compute the masses and widths of resonances that appear, scattering lengths and effective ranges of partial waves, and low-energy coefficients in the effective action. Additionally, we use these results to discuss the thermodynamics of a pion gas including pair correlations of pions with the same and opposite charge.
Warped orbifold compactifications generically admit a warp-anisotropy parameter $\alpha$ characterizing the ratio of internal to external warp exponents. In a recent work, this parameter was shown to be topologically discretized and fixed for a specific 9D model whose boundary sector supports self-dual Yang-Mills configurations with fractional instanton numbers quantized by a finite torsion exponent. Here we investigate the structure of this discretization mechanism across $(d{+}1{+}q)$-dimensional warped orbifold compactifications within the same boundary-sector class, where $d$ is the number of external dimensions, 1 is the orbifold direction, and $q$ is the dimension of a Ricci-flat internal space. We derive the general junction relation $\alpha =(1+dx)/(1-(q{-}1)x)$ with $x= ho /\sigma$, and show that boundary topological consistency with torsion exponent $N$ restricts $x$ to the discrete set $\lbrace m/(N{-}m) brace$. The number of physically allowed anisotropy sectors is $\lfloor (N{-}1)/q floor$ and decreases monotonically with increasing internal dimension $q$. A sharp uniqueness criterion emerges: when $\lceil N/2 ceil \le q\lt N$, the anisotropy is uniquely determined within this class without any selection principle. When $q\ge N$, no physical solution exists. The previously studied case $d{=}q{=}4$, $N{=}18$ is recovered as one entry in the classification, and the criterion explains why a selection principle was necessary in that case while identifying the regime where it becomes unnecessary.
Abstract Terrestrial double-$\Lambda$ hypernuclear data and astronomical observations of neutron stars provide complementary constraints on the $\Lambda \Lambda$ interaction. In this work, we investigate the $\Lambda \Lambda$ interaction within a Skyrme energy density functional framework based on the Korea–IBS–Daegu–SKKU models. We employ a Skyrme-type $\Lambda \Lambda$ interaction that includes the standard s- and p-wave terms, as well as a density-dependent term that effectively represents an $N\Lambda \Lambda$ three-body force. The s-wave terms are constrained using data on double-$\Lambda$ hypernuclei supplemented by pseudodata obtained from core + $2\Lambda$ three-body model calculations including heavier hypernuclei. We show that the data on heavier systems are essential to simultaneously constrain the two s-wave parameters. We further explore the impact of the p-wave and $N\Lambda \Lambda$ components on the neutron-star properties and find that appropriate repulsive contributions of these terms yield consistency with current neutron-star mass–radius observations. These results indicate that the present framework provides phenomenologically acceptable equations of state for dense $(N,\Lambda )$ matter over a wide range of densities and highlight the importance of future experimental data on heavier double-$\Lambda$ hypernuclei.
Abstract An analysis of the $B_s\rightarrow \phi \ell ^+ \ell ^-$ rare decay within the covariant confined quark model (CCQM) is performed in this paper. The $B_s\rightarrow \phi$ transition form factors are calculated and then used to compute the branching fractions and angular observables in various $q^2$ bins, including the forward–backward asymmetry $A_{FB}$, the longitudinal polarization $F_L$, and the optimized observables $A_i$ and $S_i$. Angular observables and branchings were calculated for the bins that were presented by the LHCb collaboration. Generally, CCQM predictions are consistent with data from the LHCb collaboration within the error bars. However, the largest discrepancy is observed in the forward–backward asymmetry of $A_{FB}$ for the bin [6,8] GeV$^2$ owing to the reverse signs. Discrepancies are also observed in the observed values of $A_{FB}$ and $A_5$ for the bins [11,12.5] and [15,18.9] GeV$^2$.
Abstract In this paper, as an application of the “Complexity = Volume” proposal, we calculate the growth of the interior of a black hole at late times for finite cutoff Jackiw–Teitelboim (JT) gravity. Due to this integrable irrelevant deformation, the spectral properties are modified nontrivially. The Einstein–Rosen bridge (ERB) length saturates faster than in pure JT gravity. We comment on the possible connection between Krylov complexity and ERB length for the deformed theory. Apart from this, we compute the emission probability of baby universes in the deformed theory and find that it changes due to the deformation parameter only if we turn on Lorentzian evolution. We also find that the saturation time of the deformed theory relative to the undeformed one depends on the inverse temperature. We also highlight the subtleties involved in the dual matrix model and comment on the possible one-cut universality. Finally, we comment on the possible correction to the volume of the moduli space arising from the nonperturbative correction of the spectral curve induced by the finite boundary cutoff.
In particle accelerators, broad characterization of the 6D beam phase space is crucial but difficult to obtain with conventional beam diagnostics. We develop a two-stage convolutional neural network that reconstructs the 6D phase space from only 16 transverse $x ext{-}y$ screen images taken at a place with dispersion by different phase-space rotation angles. The model is trained with simulation data for the KEK-Accelerator Test Facility (ATF) injector with ASTRA. The real-space images in the chicane orbit at the KEK-ATF injector were acquired by varying the RF phase of the RF electron gun and the solenoid magnetic field. From these data, we reconstructed a pseudo-6D phase-space distribution at the cathode surface, expressed through 15 2D distributions covering all pairwise coordinate combinations. The time width and spatial spread of the electron beam at the cathode showed values consistent with the measured values at KEK-ATF. Compared to existing 6D beam imaging measurement techniques such as tomography, it significantly reduces measurement time and necessary computational resources, enabling the provision of a more practical 6D phase-space measurement method.
Abstract In this work, we investigate the accretion process for several spherically symmetric black hole geometries within the framework of Bondi accretion by employing specific fluid models. Firstly, we consider a dark fluid configuration in which the ratio of pressure to energy density is assumed to be constant. In addition, we analyze an exponential dark matter distribution to characterize the ambient environment during the accretion process. The black hole spacetimes considered in this study include the global monopole solution, the ModMax black hole, and the 4D Einstein–Gauss–Bonnet gravity model. For the dark fluid model, we derive the corresponding expressions for the radial velocity, density profile, and mass accretion rate. In the case of the exponential density distribution, we obtain the associated pressure, mass accretion rate and luminosity. The behavior of these physical quantities is illustrated through a detailed graphical analysis as a function of the dimensionless radial coordinate $r/M$. It is interesting to mention here that our results show consistency for each choice of black hole.
The potential diversity in atmospheric compositions of extrasolar planets with water oceans is investigated in light of the increasing number of observed transiting exoplanets. This study explores several atmospheric configurations, including those dominated by H2, He, N2 and mixed backgrounds containing water vapor. A critical aspect of these atmospheres is the Komabayashi-Ingersoll (KI) limit, which constrains the outgoing longwave radiation (OLR) from the stratosphere and establishes an upper boundary influenced by atmospheric pressure and molecular weight. Using a one-dimensional radiative-convective equilibrium model for a gray atmosphere, we examine the relationship between OLR and surface temperature Ts. We find that the OLR initially increases with Ts, reaches a plateau, subsequently decreases, and then rises to a secondary threshold for H2 and He atmospheres. Our analysis reveals that this distinct OLR behavior, observed across varying atmospheric compositions, is governed by two key limits: the KI limit and the Simpson-Nakajima (SN) limit. While the KI limit depends on atmospheric pressure and molecular weight, the SN limit is primarily determined by water vapor concentration and is independent of other atmospheric components. Notably, the KI limit for He-dominated atmospheres is lower than the SN limit which is applicable to H2-dominated atmospheres. We have derived the limiting value formulas for the KI limit and SN limit, respectively. This study underscores the critical role of atmospheric composition and stratospheric OLR in determining the habitability of exoplanets.
The extension of the Standard Model Higgs doublet with three nonzero hypercharge triplets is examineled in this article. The triplets are charged under additional $U(1)_{L_{\mu }-L_{\tau }}$ symmetry. We investigate the stability of the electroweak vacuum at both the tree level and the two-loop level. It is observed that the vacuum stability can be satisfied up to the Planck scale using two-loop $\beta$-functions. In contrast, due to the increase in the positive effect from triplet degrees of freedom, the perturbative unitarity can be satisfied only up to $10^{12}$ GeV. The parameter space allowed from the Planck scale stability is checked for the strongly electroweak first-order phase transition. The model satisfies the strongly first-order phase transition for the triplet bare mass parameters up to the TeV scale due to the sufficient contribution to the cubic term from the triplet degrees of freedom. It is observed that this model foresees a strongly first-order phase transition for all mass ranges until the degrees of freedom become heavy enough to decouple from the thermal bath. The benchmark points satisfying the strongly first-order phase transition are tested for gravitational-wave signatures. The benchmark points that are allowed from the Planck scale stability, strongly first-order phase transition also comes out to lie in the detectable frequency range of the LISA and BBO experiments.
The scientific objective of the Reactor Experiment for Neutrino and Exotics (RENE) is to investigate sterile neutrino oscillations, particularly within the $\Delta m_{41}^{2} \sim 2$ eV2 region, through precision measurements of antineutrinos emitted by the Hanbit nuclear power plant in Yeonggwang, Korea. To support stable, long-term data acquisition for this experiment, an integrated monitoring system was developed. This system was designed for real-time monitoring of key physical parameters, including photomultiplier tube high voltage, temperature, liquid scintillator level, ambient magnetic field, radon concentration, laboratory temperature, humidity, volatile organic compounds, and thermal anomalies. Because the experiment is performed in a limited and restricted underground space called the tendon gallery, unlike existing conventional commercial-based systems, a key feature of the RENE monitoring system is its asynchronous multi-threaded architecture based on an open-source framework and the producer-consumer design pattern. In particular, this architecture completely decouples hardware communication and database operations from the main graphical user interface thread. Consequently, the responsiveness of the user interface is ensured, and overall system stability is maximized, even during the processing of large data volumes or in case of emergency. The reliability and robustness of the RENE monitoring system have been demonstrated through successful long-term operation. In this paper, the design philosophy, hardware configuration, software architecture, implementation of key features, performance evaluation, and future development plans of the RENE monitoring system are described in detail.
Recently, Fujimoto, Fukushima Weise (2019) have proposed a new colour-superconductive state, 2SC+ phase, which can be smoothly connected to the low-density baryon superfluidity in contrast to the 2SC phase. In this scenario, the neutron ^3P_2 superfluidity on the low-density side of the phase transition is inherited by unpaired d-quarks in the 2SC phase on the high-density side. Since this could be realized in hybrid stars (neutron stars containing hadronic and quark matter), the 2SC+ phase may change the properties of neutron stars compared to the traditional 2SC phase. In this work, we study the thermal evolution of hybrid stars with the 2SC+ phase for the first time. We find that NSs with the 2SC+ phase become hotter than those with the 2SC phase, and are close to the CFL phase. The ^3P_2 superfluidity plays an important role in cooling curves with not the 2SC but 2SC+ phases due to the suppression of quark β decay. We therefore point out that, if the scenario of 2SC+ phase is true, it could be specified through low-temperature observations such as Vela, 3C58, Vela Jr., and Vela-like pulsar.
Lepton-number violation (LNV) is required in leptogenesis to explain why the observable universe has more matter than antimatter. There exist two theoretical predictions about nuclear $\beta$ decay with LNV: one is neutrinoless double $\beta$ decay ($0 u 2\beta$) and the other neutrinoless quadruple $\beta$ decay ($0 u 4\beta$). In order to search for these events, we have been developing a magnetic drift chamber beta-ray analyzer (DCBA) at KEK. It consists of self-triggered drift chambers for $\beta$-ray tracking, nuclear decay source plates, and a superconducting solenoid magnet. The $\beta$-ray momentum is obtained by measuring the helical radius, the pitch angle, and the magnetic field density, and then its kinetic energy is calculated from the momentum. The test facility DCBA-T2.5 has measured the half-life of the two-neutrino double beta decay ($2 u 2\beta$) of $<^>{100}$Mo to the ground state of $<^>{100}$Ru as $T<^>{2 u 2\beta }_{1/2}=[7.23<^>{+0.99}_{-0.77}(\mathrm{stat})\pm 0.76(\mathrm{syst})] imes 10<^>{18}\, \mathrm{yr}$. The DCBA-T3 has been proposed to search for LNV events, especially for $0 u 4\beta$ of the $<^>{150}$Nd transition to $<^>{150}$Gd. It is essential to detect four $\beta$-rays with a sum energy of 2.08 MeV (Q-value) from a common start point in the source plate. This article describes the present status and the future prospects of DCBA.
We report a measurement of the gamma-gamma angular correlation in the $<^>{60}$Co cascade using a compact coincidence setup based on two unsegmented liquid-scintillator (LS) detector modules read out by photomultiplier tubes. The beta-minus decay of $<^>{60}$Co produces two prompt gamma rays of 1173 keV and 1332 keV in the well-known $4<^>+\! ightarrow \!2<^>+\! ightarrow \!0<^>+$ cascade, whose angular correlation can be described by an even-order Legendre expansion. Although unsegmented LS detectors do not provide event-by-event interaction-point information as segmented crystal scintillators or high-purity germanium arrays do, the correlation can be recovered statistically from coincidence timing in a fixed detector geometry. We fit the measured angular-correlation distribution with $W( heta )=1+A_2P_2(\cos heta )+A_4P_4(\cos heta )$, yielding $A_2=0.1018\pm 0.0146$ and $A_4=0.0116\pm 0.0183$. These values are consistent with the theoretical coefficients $A_2<^>{ m th}=0.102\,041$ and $A_4<^>{ m th}=0.009\,070$ for a pure $E2$-$E2$ cascade. This work indicates that gamma-gamma angular-correlation coefficients can be quantitatively extracted with a compact, unsegmented LS system. It provides an initial benchmark for large homogeneous scintillation geometries in which event-by-event angular tagging is unavailable, and supports the feasibility of future coincidence applications with doped LS or water-based liquid-scintillator media.
The presence of hyperons in neutron stars allows the star to cool via the hyperon direct Urca process, which can release energy from the star faster than the standard modified Urca process. Previous cooling calculations verified that hyperons can exist in the core of neutron stars and facilitate direct Urca cooling. In the current article, we first update the observational data on the thermal evolution of neutron stars. Then, adopting the latest realistic equation of state for hyperon-mixed neutron stars, the cooling of these stars is calculated, and the results are compared with the most recently updated observational data. The results confirm that the hyperon scenario can explain the thermal evolution of all observed stars, including the faster cooling of some of these stars if their fast cooling is substantially suppressed due to the presence of hyperon superfluidity in moderately massive stars.
We present an analytic phase-space and spectral framework for single-particle dynamics near the third-integer resonance in circular accelerators, emphasizing amplitude-dependent nonlinear effects. Starting from a resonant Hamiltonian in action-angle variables, we obtain elliptic-function solutions that give closed-form relations between island action, separatrix geometry, and amplitude-dependent tune for both the primary orbit and the resonance islands. Mapping this parameterization into the frequency domain yields analytic predictions for the main spectral line and higher-order sidebands, providing a quantitative interpretation of structures such as the devil's staircase. Multiturn tracking with ELEGANT shows good agreement in both phase space and spectra, establishing a rigorous, interpretable basis for analyzing nonlinear resonance effects in transverse resonance-island buckets, RF knock-out, and other resonance-island-based beam operations.
