We explore the spontaneous breaking of global baryon number for baryogenesis. We introduce a model with three majorana fermions and a complex scalar carrying baryon number charge. After symmetry breaking, the baryon asymmetry is generated below the electroweak scale via the decays of one of the majorana fermions. The main focus of the paper is the phenomenology of the Nambu-Goldstone boson of $U(1{)}_B$, which we call the bajoron. With small sources of explicit baryon number violation, the bajoron acquires a small mass and is generally very long-lived. The model avoids proton decay, satisfies cosmological constraints, and offers interesting collider phenomenology for the Large Hadron Collider. These long-lived particles tied to baryogenesis strongly support the development of far-detector experiments such as MATHUSLA, FASER, SHiP, and others.

In this work, we provide a comprehensive study of fermion-portal dark matter models in the freeze-in regime at a future muon collider. For different possible nonsinglet fermion portals, we calculate the upper bound on the mediator’s mass arising from the relic abundance calculation and discuss the reach of a future muon collider in probing their viable parameter space in prompt and long-lived particle search strategies. In particular, we develop rudimentary search strategies in the prompt region and show that cuts on the invariant dilepton or dijet masses, the missing transverse mass $M_{T2}$, pseudorapidity and energy of leptons or jets, and the opening angle between the lepton or the jet pair can be employed to subtract the Standard Model background. In the long-lived particle regime, we discuss the signals of each model and calculate their event counts. In this region, the lepton-(quark-)portal model signal consists of charged tracks ($R$-hadrons) that either decay in the detector to give rise to a displaced lepton (jet) signature, or are detector stable and give rise to heavy stable charged track signals. As a byproduct, a pipeline is developed for including the nontrivial parton distribution function of a muon component inside a muon beam; it is shown that this leads to nontrivial effects on the kinematic distributions and attainable significances. We also highlight phenomenological features of all models unique to a muon collider and hope our results, for this motivated and broad class of dark matter models, inform the design of a future muon collider detector. We also speculate on suggestions for improving the sensitivity of a muon collider detector to long-lived particle signals in fermion-portal models.

Worldwide efforts are underway to detect neutrinoless double beta ($0\nu \beta \beta$) decay using experiments based on various technologies and target isotopes. Future experiments in this regard aim to exclude the inverted order (IO) condition or explore the normal order (NO) band. Consequently, comparing the sensitivities of proposed $0\nu \beta \beta$ decay experiments with promising prospects is essential. The current study adopts sensitivity metrics, including exclusion and discovery sensitivities, half-life sensitivities, and $m_{\beta \beta }$ sensitivities, to provide a comprehensive evaluation of ten typical promising experiments: LEGEND, CDEX, nEXO, XLZD, PandaX, NEXT, KamLAND-Zen, JUNO, $\mathrm{SNO}+$, and CUPID, and highlight their unique features. Based on reported experimental parameters, the concept of a “technical line” is introduced to determine the location that each experiment may realize in the $\xi$ and ${\lambda }_b$ space, where $\xi$ represents the sensitive exposure per year, and ${\lambda }_b$ denotes the expected annual rate of background events. Half-life sensitivities for the selected experiments are calculated, some of them in multiple phases and others in conservative or aggressive condition. The results indicate that increasing the operation time is more beneficial for zero-background experiments, which also demonstrate greater competitiveness in discovery sensitivity. $m_{\beta \beta }$ sensitivities are presented as uncertainty bands arising from the nuclear matrix element uncertainties. Additionally, half-life and $m_{\beta \beta }$ sensitivities are estimated under ideal conditions also in the form of uncertainty bands, where only irreducible $2\nu \beta \beta$ and solar B-8 neutrino induced background remain.

In light of current constraints from supersymmetry (SUSY) searches within the LHC as well as findings from direct dark matter detection experiments such as LUX-ZEPLIN (LZ), we revisit the three-family Pati-Salam model derived from intersecting D6-branes in type IIA string theory compactified on the $T^6/({\mathbb{Z}}_2\times {\mathbb{Z}}_2)$ orientifold, known for its realistic low-energy phenomenology. Because the muon anomalous magnetic moment might be in accordance with the Standard Model prediction, we conduct a comprehensive scan over the model’s parameter space for each sign of the Higgsino mass parameter, $\mu <0$ and $\mu >0$. We found that a gravitino mass is typically greater than 1.5 TeV in both scenarios while simultaneously satisfying the LHC SUSY bounds, B-physics observables, along with the Higgs mass constraint. Within the experimentally viable region of the parameter space, the mass spectra of sparticles are found to fall within the following ranges: Gluinos lie in the range of 2–18 TeV, the first- and second-generation squarks and sleptons span 3–16 TeV and 1–6 TeV, respectively. For third-generation sfermions, the lightest stop, which can satisfy the dark matter relic density through neutralino-stop coannihilation consistent with the Planck $5\sigma$ bounds, has a mass in the range of 0.5–1.2 TeV. Note that the lightest neutralino will be as heavy as 2.9 TeV. Additionally, the lightest stau could be as light as 200 GeV, as well as heavy up to 5.2 TeV. We further identify several viable mechanisms, including multiple coannihilation channels and resonance mechanisms, and the observed dark matter relic abundance is successfully realized.

Quantum simulations of lattice gauge theories offer the potential to directly study the nonperturbative dynamics of quantum chromodynamics, but naive analyses suggest that they require large computational resources. Large $N_c$ expansions are performed to order $1/N_c$ to simplify the Hamiltonian of pure $\mathrm{SU}(N_c)$ lattice gauge theories. A reformulation of the electric basis is introduced with a truncation strategy based on the construction of local Krylov subspaces with plaquette operators. Numerical simulations show that these truncated Hamiltonians are consistent with traditional lattice calculations at relatively small couplings. It is shown that the computational resources required for quantum simulation of time evolution generated by these Hamiltonians is 17–19 orders of magnitude smaller than previous approaches, provided that the truncations in this work can reach lattice spacings in three-dimensional simulations comparable to the two-dimensional simulations performed.

We present the first lattice quantum chromodynamics (QCD) determination of coupled $D{D}_s^{*}$ and $D^{*}{D}_s$ scattering amplitudes in the $J^P=1^{+}$ channel and elastic $D{D}_s$ scattering amplitude in the $J^P=0^{+}$ channel. The aim is to investigate whether tetraquarks with flavor $cc\overline{u}\overline{s}$ exist in the region near threshold. Lattice QCD ensembles from the CLS consortium with $m_{\pi }\sim 280\mathrm{MeV}$, $a\sim 0.09\mathrm{fm}$ and $L/a=24$, 32 are utilized. Finite-volume spectra are determined via variational analysis of two-point correlation matrices, computed using large bases of operators resembling bilocal two-meson structures within the distillation framework. The scattering matrix for partial wave $l=0$ is determined using lattice eigenenergies from multiple inertial frames following Lüscher’s formalism as well as following the solutions of Lippmann-Schwinger equation in the finite-volume on a plane-wave basis. We observe small nonzero energy shifts in the simulated spectra from the noninteracting scenario in both the channels studied, which points to rather weak nontrivial interactions between the mesons involved. Despite the nonzero energy shifts, the lattice-extracted $S$-wave amplitudes do not carry signatures of any hadron pole features in the physical amplitudes in the energy region near the threshold.

Tritium, predominantly produced through spallation reactions caused by cosmic ray interactions, is a significant radioactive background for silicon-based rare event detection experiments, such as dark matter searches. We have investigated the feasibility of removing cosmogenic tritium from high-purity silicon intended for use in low-background experiments. We demonstrate that significant tritium removal is possible through diffusion by subjecting silicon to high-temperature ($>400°\mathrm{C}$) baking. Using an analytical model for the detrapping and diffusion of tritium in silicon, our measurements indicate that cosmogenic tritium diffusion constants are comparable to previous measurements of thermally introduced tritium, with complete detrapping and removal achievable above $750°\mathrm{C}$. This approach has the potential to alleviate the stringent constraints of cosmic ray exposure prior to device fabrication and significantly reduce the cosmogenic tritium backgrounds of silicon-based detectors for next-generation rare event searches.

In this paper, we investigate the transport coefficients of a strongly coupled plasma in the context of holographic QCD models based on Einstein-dilaton gravity that are compatible with linear confinement at zero temperature. At finite temperature, the holographic model is characterized by an asymptotically anti–de Sitter black hole coupled to a scalar field, the dilaton, which is quadratic in the radial direction. The inclusion of the scalar field results in an explicit breaking of the conformal symmetry in the dual field theory. In such systems, the Hawking temperature of the black hole corresponds to the plasma temperature in the dual field theory. We confirm the existence of a minimum temperature $T_{\min }$, above which two distinct classes of black hole solutions emerge: one corresponding to large black holes and the other to small black holes. We calculate some thermodynamic quantities—such as entropy, specific heat, and speed of sound—and find results that are consistent with similar holographic models. We calculate the quasinormal modes of the tensor and vector sectors using the pseudospectral method. In the hydrodynamic regime, we derive the dispersion relation for the vector sector, from which we extract the shear viscosity and the ratio $\eta /s=1/4\pi$. The bulk viscosity is calculated using the Kubo formula in the scalar sector. Finally, our results for the speed of sound are compared with the lattice QCD predictions, and our results for the bulk viscosity are compared with those reported by the JETSCAPE collaboration.

We develop the method adjusting the Faddeev-Popov factorization procedure for the quantization of generic reducible gauge theories with linearly dependent generators and apply it to the first stage reducible model of second rank antisymmetric fermion in $d$-dimensional anti–de Sitter (AdS) spacetime. The method consists of nested factorizations of the gauge group volume for the determination of the consistently defined delta function of reduced gauge conditions, group integration measure, and gauge-fixed contribution of ghosts. It is compared to the Batalin-Vilkovisky (BV) formalism of quantizing theories with linearly dependent generators and shown to be equivalent to it for first stage reducible theories. Nevertheless, the method under consideration, unlike the BV formalism, from the very beginning leads to the functional integral with fewer number of ghosts. Using this method, we quantized the variant of fermionic totally antisymmetric tensor-spinor theory in AdS space and derived its effective action in terms of the functional determinants of special Dirac-type operators. Limitations of the method are also discussed along with the prospects of its extension to higher reducibility stages and higher rank models of antisymmetric fermions.

We study the entanglement entropy of a massive scalar field in the background of the Einstein universe. We determine numerically the structure of the UV-divergent terms. We study analytically the IR term that originates in the long-range correlations arising from the field zero mode on the sphere. We compare with previous results for a scalar field in a de Sitter or an anti–de Sitter background.

This paper investigates the power and efficiency of energy extraction via magnetic reconnection in the Kerr-Sen-${\mathrm{AdS}}_4$ black hole, focusing primarily on the circular orbit region and the plunging region. After introducing the black hole event horizon, boundary of the ergosphere, and photon sphere radius, we first study the energy extraction via magnetic reconnection in circular orbit region. We plot the allowed regions for energy extraction and present the energy extraction power and efficiency, comparing them with the Blandford-Znajek (BZ) mechanism. It was found that energy extraction is still possible even at a spin parameter of 0.5, which is lower than previous results, and the power can be higher than the BZ process in certain regions. In addition, we find the dilatonic scalar charge $b$ and the anti-de Sitter (AdS) radius $l$ contribute to lowering the spin threshold required for energy extraction. We also study the energy extraction in the plunging region by analyzing the allowed regions for energy extraction, and the power as well as efficiency. It was found that the energy extraction is possible even at a spin as low as 0.25. Especially, we find that parameter $b$ promotes lowering the energy extraction spin threshold while $l$ suppresses it, which is different from the circular orbit case. Moreover, the power and efficiency of energy extraction in the plunging region are higher than in the circular orbit region, indicating a stronger energy extraction capability in the plunging region.

In the near-horizon region, black holes exhibit an infinite-dimensional symmetry reminiscent of the Bondi-Metzner-Sachs supertranslations. The conserved charges associated with this symmetry can be computed in gravitational theories of arbitrary spacetime dimension and involving curvature terms of any order. In Lovelock theory, for instance, these charges take the form of nested Lagrangian densities corresponding to topological invariants, each weighted by the supertranslation function—thus providing a natural generalization of the Wald entropy formula. In four dimensions, the computation of the supertranslation charge reduces to the evaluation of the Jackiw-Teitelboim action on the two-dimensional spacelike sections of the event horizon.

We show that enhancement of the axion relic abundance compared to the standard misalignment contribution generically leads to the production of nonzero-momentum axion modes, resulting in warm dark matter behavior and enhanced isocurvature perturbations. It leads to universal constraints on the axion parameter space that are independent of detailed model assumptions and cosmological history. For models enhancing relic abundance with gradient axion modes, observations of the Lyman-$\alpha$ forest impose a lower bound on the axion decay constant, $f_a\gtrsim {10}^{15}\mathrm{GeV}({10}^{-18}\mathrm{eV}/m_a)$, from the free streaming effect. For models relying on the delay of coherent axion oscillations, we obtain a slightly weaker bound, $f_a\gtrsim {10}^{14}\mathrm{GeV}({10}^{-18}\mathrm{eV}/m_a)$. We make relatively conservative choices to establish these universal bounds but also provide scaling parameters that can be calibrated for stronger constraints in concrete models and updated as observations improve.

Recently the Dark Energy Spectroscopic Instrument (DESI) provided constraints on the expansion history from their Data Release 2. The DESI baryon acoustic oscillation measurements are well described by a flat $\mathrm{\Lambda }\mathrm{CDM}$ model, but the preferred parameters are in mild ($2.3\sigma$) tension with those determined from the cosmic microwave background. The DESI Collaboration has already explored a variety of solutions to this tension relying on variations in the late-time evolution of dark energy. Here we test an alternative—the introduction of an “early dark energy” (EDE) component. We find that EDE models can alleviate the tension, though they lead to differences in other cosmological parameters that have observational implications. Particularly the EDE models that fit the acoustic datasets prefer lower ${\mathrm{\Omega }}_m$, higher $H_0$, $n_s$ and ${\sigma }_8$ in contrast to the late-time solutions. We discuss the current status and near-future prospects for distinguishing amongst these solutions.

Detecting orbital eccentricity in a stellar-mass black-hole merger would point to a nonisolated formation channel. Eccentric binaries can form in dense stellar environments such as globular clusters or active galactic nuclei or from triple stellar systems in the Galactic field. However, confidently measuring eccentricity is challenging—short signals from high-mass eccentric mergers can mimic spin-induced precession, making the two effects hard to disentangle. This degeneracy weakens considerably for longer-duration signals. Here, GW200208_222617 provides a rare opportunity. Originating from a relatively low-mass binary with source-frame chirp mass $\sim 20M_{\odot }$, its gravitational-wave signal spanned $\sim 14$ orbital cycles in band, with no indication of data quality issues. Previous analyses for quasicircular binaries found no evidence for spin precession, and multiple subsequent studies found the data to favor an eccentric merger despite notable technical differences. All in all, we believe GW200208_222617 is the black-hole merger event from Gravitational-Wave Transient Catalog-3 with the least ambiguous detection of eccentricity. We present a critical discussion of properties and astrophysical interpretation of GW200208_222617 as an eccentric black-hole merger using models of field triples, globular clusters, and active galactic nuclei. We find that if GW200208_222617 was indeed eccentric, its origin is consistent with a field triple or globular cluster. Formation in the inner regions of an active galactic nucleus is disfavored. The outer regions of such a disk remain a viable origin for GW200208_222617; we demonstrate how future detections of eccentric mergers formed in such environments could be powerful tools for constraining the disk geometry.

A method for investigating the sensitivity of the tip of the red giant branch (TRGB) I band magnitude $M_I$ to stellar input physics is presented. We compute a grid of $\sim 125,000$ theoretical stellar models with varying mass, initial helium abundance, and initial metallicity, and train a machine learning emulator to predict $M_I$ as a function of these parameters. First, our emulator can be used to theoretically predict $M_I$ in a given galaxy using Monte Carlo sampling. As an example, we predict $M_I=-3.87_{-0.08}^{+0.11}$ in the Large Magellanic Cloud (F20). Second, our emulator enables a direct comparison of theoretical predictions for $M_I$ with empirical calibrations to constrain stellar modeling parameters using Bayesian Markov chain Monte Carlo methods. We demonstrate this by using empirical TRGB calibrations to obtain new independent measurements of the metallicity in three galaxies. We find ${\log }_{10}(Z)=-2.167_{-0.492}^{+0.404}$ and ${\log }_{10}(Z)=-2.098_{-0.528}^{+0.388}$ in the Large Magellanic Cloud (LMC, F20 and Y19, respectively), ${\log }_{10}(Z)=-2.146_{-0.505}^{+0.400}$ in NGC 4258, and ${\log }_{10}(Z)=-2.143_{-0.508}^{+0.401}$ in $\omega$-Centauri. The LMC and NGC 4258 measurements are consistent with other measurements within $<1\sigma$ errors, and the $\omega$-Centauri measurements are within $<2\sigma$ errors.

Fragmentation functions (FFs) are crucial nonperturbative components in quantum chromodynamics (QCD), playing a vital role in predictions and understanding of the hadronization process. In this paper, we present the FFs for $K_S^0$, $\eta$, ${\pi }^0$ mesons, and $\mathrm{\Lambda }$ baryons in the context of global QCD analysis. The data included in the fit are from single inclusive $e^{+}{e}^{-}$ annihilation (SIA), semi-inclusive deep-inelastic scattering (SIDIS) and proton-proton collisions, with kinematic cuts carefully applied to ensure validity of collinear factorization and perturbative QCD expansion. For the first time, data from SIDIS and hadron-in-jet production in SIA have been incorporated into the extraction of FFs for light-flavor neutral hadrons. Our analysis reveals that these data play a critical role in constraining the gluon distribution, and in distinguishing between different quark flavors. Pulls from different datasets are also studied by performing alternative fits with systematically subtracting groups of data from the nominal fit. For the quality of the fit, good ${\chi }^2$ values are achieved for most of the datasets, and FFs are generally well constrained within the momentum fraction region (0.1,0.5). The extracted $K_S^0$ fragmentation functions, together with the $K_S^0$ FFs constructed from $K^{\pm }$ FFs via isospin symmetry, are used to test isospin symmetry in kaon fragmentation. Although a definitive conclusion cannot be reached yet, these studies have identified several potential measurements that can be performed at existing facilities, which may ultimately help us to arrive at a conclusive answer. With the comprehensive species of FFs extracted within the NPC framework, we are able to perform a test on the momentum sum rule with the light-flavor charged and neutral hadrons. These neutral hadrons are found to carry a relatively smaller fraction of the fragmenting parton’s momentum compared to the charged ones. The central and Hessian error sets of the fitted FFs, denoted as NPC23, are publicly available in the form of LHAPDF6 grids.

Using data samples of $(10087\pm 44)\times {10}^6$ $J/\psi$ events and $(2712.4\pm 14.3)\times {10}^6$ $\psi (3686)$ events collected with the BESIII detector at the BEPCII collider, we search for the $CP$ violating decays $J/\psi \to K_S^0{K}_S^0$ and $\psi (3686)\to K_S^0{K}_S^0$. No significant signals are observed over the expected background yields. The upper limits on their branching fractions are set as $\mathcal{B}(J/\psi \to K_S^0{K}_S^0)<4.7\times {10}^{-9}$ and $\mathcal{B}(\psi (3686)\to K_S^0{K}_S^0)<1.1\times {10}^{-8}$ at the 90% confidence level. These results improve the previous limits by a factor of three for $J/\psi \to K_S^0{K}_S^0$ and two orders of magnitude for $\psi (3686)\to K_S^0{K}_S^0$.

We propose to use interpolating operators for lattice quantum chromodynamics calculations of highly boosted pions and nucleons with kinematically enhanced ground-state overlap factors at large momentum. Because this kinematic enhancement applies to the signal but not the variance of the correlation function, these interpolating operators can achieve better signal-to-noise ratios at large momentum. We perform proof-of-principle calculations with boosted pions and nucleons using close-to-physical and larger quark masses to explore the utility of our proposal. Results for effective energies and matrix elements, as well as Lanczos ground-state energy estimators, are consistent with theoretical expectations for signal-to-noise improvement at large momenta.

Using a data sample of $e^{+}{e}^{-}$ collision data corresponding to an integrated luminosity of $20.3{\mathrm{fb}}^{-1}$ collected by the BESIII detector at the BEPCII collider, we present an observation of transverse polarization and a complete determination of the psionic form factors of the $\mathrm{\Lambda }$ hyperon in $e^{+}{e}^{-}\to \mathrm{\Lambda }\overline{\mathrm{\Lambda }}$ decay with the entangled $\mathrm{\Lambda }-\overline{\mathrm{\Lambda }}$ pair at $\sqrt{s}=3.773\mathrm{GeV}$. The relative phase between the psionic form factors is determined to be $\mathrm{\Delta }\mathrm{\Phi }=(1.53\pm 0.36\pm 0.03)\mathrm{rad}$ with a significance of 5.5 $\sigma$ taking into account systematic uncertainty. This result indicates a nonzero phase between the transition amplitudes of the $\mathrm{\Lambda }\overline{\mathrm{\Lambda }}$ helicity states. Additionally, we measure the angular distribution parameter and the modulus of the ratio between the psionic form factors to be $\eta =0.86\pm 0.05\pm 0.03$ and $R(s)=|G_E(s)/G_M(s)|=0.47\pm 0.08\pm 0.05$, where the first uncertainty is statistical and the second systematic.