We introduce an in-depth study of an unprobed phenomenological minimal supersymmetric Standard Model region offering a natural solution to dark matter. Since the 1980s this region has been referred to as the “bulk,” consisting of sub 200 GeV neutralinos and right-handed smuons. The bulk satisfies recent muon $g_{\mu }-2$ measurements and sustains consistency with all presently operating SUSY experiments and LHC constraints. Initial ingress into the bulk will arrive soon via the LUX-ZEPLIN 1000-day experiment. The ATLAS Collaboration at the LHC has confirmed that observation of these light right-handed smuon events can occur at the ongoing LHC Run 3 and forthcoming High-Luminosity LHC. Moreover, the future FCC-ee and CEPC circular colliders should handily observe the events.

Motivated by the recent Belle II result indicating a $2.7\sigma$ excess of $B^{+}\to K^{+}+E_{\mathrm{miss}}$ events compared to the Standard Model (SM) prediction for $B^{+}\to K^{+}\nu \overline{\nu }$, we explore an explanation to this anomaly based on a Kim-Shifman-Vainshtein-Zakharov-type QCD axion model featuring a Peccei-Quinn (PQ) symmetry breaking at high scale, which can provide a solution to the strong $CP$ problem with dark matter relic abundance. The model contains a PQ-charged scalar leptoquark which can interact with the SM quarks only via mass mixing of the latter with vectorlike quarks. The mixing between SM and vectorlike quarks is determined by the PQ mass scales and can explain the excess $B^{+}\to K^{+}+E_{\mathrm{miss}}$ events while respecting other flavor constraints. The same PQ-charged scalar leptoquarks and vectorlike quarks also mediate the two-loop radiative neutrino masses.

An accurate calculation of the leading-order hadronic vacuum polarization (LOHVP) contribution to the anomalous magnetic moment of the muon ($a_{\mu }$) is key to determining whether a discrepancy, suggesting new physics, exists between the Standard Model and experimental results. This calculation can be expressed as an integral over Euclidean time of a current-current correlator $G(t)$, where $G(t)$ can be calculated using lattice QCD or, with dispersion relations, from experimental data for $e^{+}{e}^{-}\to \text{hadrons}$. The BMW/DMZ collaboration recently presented a hybrid approach in which $G(t)$ is calculated using lattice QCD for most of the contributing $t$ range, but using experimental data for the largest $t$ (lowest energy) region. Here we study the advantages of varying the position $t=t_1$ separating lattice QCD from data-driven contributions. The total LOHVP contribution should be independent of $t_1$, providing both a test of the experimental input and the robustness of the hybrid approach. We use this criterion and a correlated fit to show that Fermilab/HPQCD/MILC lattice QCD results from 2019 strongly favor the CMD-3 cross section data for $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}$ over a combination of earlier experimental results for this channel. Further, the resulting total LOHVP contribution obtained is consistent with the result obtained by BMW/DMZ, and supports the scenario in which there is no significant discrepancy between the experimental value for $a_{\mu }$ and that expected in the Standard Model. We then discuss how improved lattice results in this hybrid approach could provide a more accurate total LOHVP across a wider range of $t_1$ values with an uncertainty that is smaller than that from either lattice QCD or data-driven approaches on their own.

We present the ground state energy spectra of two-flavored heavy dibaryons in the spin-singlet channel. In particular, the ground state masses of ${\mathrm{\Omega }}_{llQ}{\mathrm{\Omega }}_{llQ},{\mathrm{\Omega }}_{QlQ}{\mathrm{\Omega }}_{llQ}$, and ${\mathrm{\Omega }}_{QlQ}{\mathrm{\Omega }}_{QlQ}$ states are computed and compared with their respective lowest noninteracting energy levels, where the flavor $Q\in (c,b)$ denotes charm and bottom quarks, and the other flavor $l\in s,c,b$ represents strange, charm and bottom, respectively. Considering their valence quark structures, these hadrons could be thought of as the heavy flavor analogs of spin-singlet nucleon-nucleon states. The gauge configurations employed in this study are highly improved staggered quark ensembles with $N_f=2+1+1$ flavors, generated by the MILC collaboration, at four lattice spacings, namely $a=0.1207$, 0.0888, 0.0582, and 0.0448 fm. The aforementioned states are also computed at different quark masses, between $m_s\le m_l\le m_b$, including at unphysical heavy quark masses, to explore the quark mass dependence of any possible binding. For the dibaryon states ${\mathrm{\Omega }}_{bbc}{\mathrm{\Omega }}_{bbc},{\mathrm{\Omega }}_{ccb}{\mathrm{\Omega }}_{ccb}$, and ${\mathrm{\Omega }}_{ccb}{\mathrm{\Omega }}_{bbc}$, we find a clear evidence of an energy level below their respective noninteracting energy levels. In addition, for these dibaryons at quark masses $m_c<m_l\le m_b$, a trend is found where the gap, between the lowest energy levels and the respective lowest noninteracting levels, increases as the quark mass $m_l$ increases. We also study the heavy quark spin-symmetry and its breaking for these heavy dibaryons.

In two spacetime dimensions staggered fermions are minimally doubled, like Karsten-Wilczek and Boriçi-Creutz fermions. A continuum eigenvalue is thus represented by a pair of near-degenerate eigenvalues, with the splitting $\delta$ quantifying the cutoff induced taste symmetry breaking. We use the quenched Schwinger model to determine the low-lying fermionic eigenvalues (with 0, 1 or 3 steps of stout smearing) and analyze them in view of the global topological charge $q\in \mathbb{Z}$ of the gauge background. For taste splittings pertinent to would-be zero modes, we find asymptotic Symanzik scaling of the form ${\delta }_{\mathrm{wzm}}\propto a^2$ with link smearing, and ${\delta }_{\mathrm{wzm}}\propto a$ without, for each action. For taste splittings pertinent to nontopological modes, staggered splittings scale as ${\delta }_{\mathrm{ntm}}\propto a^p$ (where $p\simeq 2$ with smearing and $p=1$ without), while Karsten-Wilczek and Boriçi-Creutz fermions scale as ${\delta }_{\mathrm{ntm}}\propto a$ (regardless of the smearing level). Large corrections are seen with smearing.

In the present work, we investigate the production of $X(4630)$ and $Y(4626)$ in $B^{+}$ and $B_s^0$ decays, where $X(4630)$ and $Y(4626)$ are considered as the $C$- parity pigeon pair in the $D_s^{*+}{D}_{s1}(2536{)}^{-}$ molecular frame. The branching fractions of $B^{+}\to K^{+}X(4630)/Y(4626)$ and $B_s^0\to \eta X(4630)/Y(4626)$ have been evaluated using an effective Lagrangian approach, which are of the order of ${10}^{-5}$ and the ratios of these branching fractions are almost independent on the model parameter. Based on the present estimations, we propose to search $Y(4626)$ in the process $B^{+}\to K^{+}J/\psi {\eta }^{(\prime )}$, which should be accessible by the LHCb and Belle II Collaborations.

We develop a framework combining the higher-twist formalism of exclusive processes in the $s$ channel with the semiclassical effective description of small-$x$ physics in the $t$ channel. We apply it to transversely polarized light vector meson production, ${\gamma }^{*}p\to V(\rho ,\phi ,\omega )p$, which starts at the next-to-leading power and for which a purely collinear treatment leads to end-point singularities. The result is obtained in the most general kinematics, including both forward and nonforward cases by preserving the full impact parameter dependence in the nonperturbative correlators, in both momentum and coordinate space representations. A systematic expansion of the Wilson lines in terms of Reggeized gluon fields is performed in order to obtain the results in the weak-field BFKL approximation. These new results will allow for investigating the dilute-to-dense regime transition of quantum chromodynamics for a wide class of observables.

We analyze the latest LHCb data on the ${\pi }^{+}{\pi }^{-}$ spectrum in the isospin-violating $X(3872)\to J/\psi {\pi }^{+}{\pi }^{-}$ decay, based on dispersion theory to deal with the $\pi \pi$ final state interactions. Additionally, the isospin breaking effects are properly introduced, allowing for a reliable and accurate extraction of the ratio, $R_X$, between the $X(3872)$ couplings to the $J/\psi \rho$ and $J/\psi \omega$ channels from the data. We find very good agreement with the LHCb data for the whole range of the ${\pi }^{+}{\pi }^{-}$ invariant mass, and $R_X$ is determined to be $0.26\pm 0.03$. Using this value, we make predictions for the ${\pi }^{+}{\pi }^0{\pi }^{-}$ mass distribution in the $X(3872)\to J/\psi {\pi }^{+}{\pi }^0{\pi }^{-}$ process, which is currently accessible by the BESIII Collaboration, and update a prediction for the pole positions of the isovector partner states of the $X(3872)$, $W_{c1}$, with $I(J^{PC})=1(1^{++})$.

In this work a comprehensive analysis of the mass spectrum and decay properties of charmonium states within a relativistic framework is carried out. The present experimental status of charmonium states is reviewed. Utilizing a screened potential model, we compute the spectra and various decay widths for the $c\overline{c}$ bound system, comparing our results with experimental data and existing theoretical models. We calculate the decay constants, $E1$ and $M1$ transitions, and annihilation decay widths, confirming the consistency of our model with experimental observations for well-established charmonium states. The interpretation of charmoniumlike states $X(4140)$, $X(4274)$, and $X(4500)$ as $P$-wave charmonium states and $\psi (4040)$, $\psi (3770)$, $\psi (4160)$, $\psi (4230)$, $\psi (4360)$, $\psi (4415)$, $Y(4500)$, and $Y(4360)$ as $S-D$ mixed charmonium states is carried out.

We measure the time-integrated $CP$ asymmetry in $D^0\to K_S^0{K}_S^0$ decays reconstructed in $e^{+}{e}^{-}\to c\overline{c}$ events collected by the Belle and Belle II experiments. The corresponding data samples have integrated luminosities of 980 and $428{\mathrm{fb}}^{-1}$, respectively. The $D^0$ decays are required to originate from the $D^{*+}\to D^0{\pi }^{+}$ decay, which determines the charm flavor at production time. A control sample of $D^0\to K^{+}{K}^{-}$ decays is used to correct for production and detection asymmetries. The result, $(-1.4\pm 1.3(\mathrm{stat})\pm 0.1(\mathrm{syst}))\%$, is consistent with previous determinations and with $CP$ symmetry.

In the duality of 3-dimensional anti de-Sitter (AdS) spacetime and 2-dimensional conformal field theory (CFT), it was argued that the holographic entanglement entropy between two timelike separated events needs both timelike and spacelike geodesics. This paper studies the possibility of using smooth spacelike geodesics to connect two timelike separated events of boundary. We find that in a spherically symmetry Schwarzschild anti-de Sitter spacetime black hole, smooth spacelike geodesics can connect timelike-separated points by winding around the horizon multiple times. A similar result will also happen in a three-dimensional asymptotically AdS black hole that contains a photon ring in the bulk. Our result suggests that, if there is a photon ring, then the timelike entanglement entropy in the ${\mathrm{AdS}}_3/{\mathrm{CFT}}_2$ duality may not have an imaginary part. The result implies that the bulk photon ring may play an important role in understanding analytical behaviors of the entanglement spectrum for ${\mathrm{AdS}}_3/{\mathrm{CFT}}_2$ duality.

Precise measurements of neutron star observables (such as mass and radius) allow one to constrain the equations of state for supranuclear matter and develop a stronger understanding of nuclear physics. The Neutron star Interior Composition ExploreR (NICER) tracks x-ray hotspots on rotating NSs and is able to infer precise information about the compactness of the star. Gravitational waves carry information about the tidal deformability (related to the tidal Love number) of neutron stars, which has been measured by the LIGO/Virgo/KAGRA collaboration. These two observables enjoy an approximately universal property between each other that is insensitive to the equations of state (the “universal Love-C relation”). In this paper, we focus on deriving two analytic expressions for the Love-C relations that are ready to use and improve upon previous analytic expressions. The first model is inspired by a Newtonian polytrope, whose perturbation to the gravitational potential can be found analytically. We extend this Newtonian model to the relativistic regime by providing a quadratic fit to the gravitational potential perturbation against stellar compactness. The second model makes use of the Tolman VII model and adopts a spectral expansion with Chebyshev polynomials, which converges faster than the Taylor expansions used in previous work. We find that the first model provides a more accurate description of the Love-C relation for realistic neutron stars than the second model, and it provides the best expression among all other analytic relations studied here in terms of describing the averaged numerical Love-C relation. These new models are not only useful in practice, but they also show the power and importance of analytic modeling of neutron stars.

We study initially unbound systems of two black holes using numerical relativity (NR) simulations performed with gr-athena++. We focus on regions of the parameter space close to the transition from scatterings to dynamical captures, considering equal mass and spin-aligned configurations, as well as unequal mass and nonspinning ones. The numerical results are then used to validate the effective-one-body (EOB) model teobresums-dalí for dynamical captures and scatterings. We find good agreement for the waveform phenomenologies, scattering angles, mismatches, and energetics in the low energy regime ($E_0\lesssim 1.02M$). In particular, mismatches weighted with the zero-detuned, high-power noise spectral density of Advanced LIGO are typically below or around the 1% level, with only a few cases—corresponding to spinning binaries—slightly above the 3% threshold, thus suggesting the usability of teobresums-dalí for current data analysis of low-energy scatterings and dynamical captures. We also discuss dynamical captures in the test-mass limit by solving numerically the Zerilli equation with the time domain code rwzhyp. The latter analysis provides valuable insights into both the analytical noncircular corrections of the EOB waveform and the integration of NR Weyl scalars.

The interplay between cosmology and strongly coupled dynamics can yield transient spectral features that vanish at late times, but which may leave behind phenomenological signatures in the spectrum of primordial fluctuations. Of particular interest are strongly coupled extensions of the standard model featuring approximate conformal invariance. In flat space, the spectral density for a scalar operator in a conformal field theory is characterized by a continuum with scaling law governed by the dimension of the operator, and is otherwise featureless. Anti–de Sitter/conformal field theory arguments suggest that for large $N$, in an inflationary background with Hubble rate $H$, this continuum is gapped. We demonstrate that there can be additional peak structures that become sharp and particlelike at phenomenologically interesting regions in parameter space, and we estimate their contribution to cosmological observables. We find phenomena that are potentially observable in future experiments that are unique to these models, including displaced oscillatory features in the squeezed limit of the bispectrum. These particles can be either fundamental, and localized to a UV brane, or composite at the Hubble scale, $H$, and bound to a horizon in the bulk of the 5D geometry. We comment on how stabilization of conformal symmetry breaking vacua can be correlated with these spectral features and their phenomenology.

The cosmological event horizons are observer dependent, which might result in a paradox. As an example, in a ${\mathrm{dS}}_2$ multiverse model, there are entanglement islands in crunching regions encoding the information of regions near future infinity of inflating or Minkowski bubbles; however, for two observers in different bubbles, since their island regions overlap, both observers will be able to get access to the information encoded in the overlapping region, indicating a violation of the no-cloning theorem. In this paper, we present a different resolution to this paradox. Based on the Petz Rényi mutual information, we show that besides the quantum extremal surfaces, there might be another boundary for the island in corresponding spacetime so that the island regions are bounded by “division points” rather than extending to the rest of the entire spacetime. We also discuss the implications of our result.

A space-dependent mean for cosmological perturbations negates the ansatz of statistical homogeneity and isotropy, and hence ergodicity. In this work, we construct such a primordial mean of scalar perturbations from an alternative quantum initial state (coherent state) and examine the associated power and bispectra. A multitude of cosmological tests based on these spectra are discussed. We find that current cosmological data do not favor a primordial mean over large scales and strong constraints arise from the limit on bispectrum from Planck data. At small scales, this hypothesis can be tested by future observables such as $\mu$ distortion of cosmic microwave background.

Burst searches identify gravitational-wave signals in the detector data without use of a specific signal model, unlike the matched-filter searches that correlate data with simulated signal waveforms (templates). While matched filters are optimal for detection of known signals in the Gaussian noise, the burst searches can be more efficient in finding unusual events not covered by templates or those affected by non-Gaussian noise artifacts. Here, we report the detection of 3 gravitational wave signals that are uncovered by a burst search coherent WaveBurst (cWB) optimized for the detection of binary black hole mergers. They were found in the data from the LIGO/Virgo’s third observing run (O3) with a combined significance of $3.6\sigma$. Each event appears to be a binary black hole merger not previously reported by the LIGO/Virgo’s matched-filter searches. The most significant event has a reconstructed primary component in the upper mass gap ($m_1=70_{-18}^{+36}{M}_{\odot }$), and unusually low mass ratio ($m_2/m_1\sim 0.3$), implying a dynamical or active galactic nucleus origin. The three new events are consistent with the expected number of cWB-only detections in the O3 run, and belong to the stellar-mass binary population with the total masses in the $70–100M_{\odot }$ range.

The successful detection of continuous gravitational waves from spinning neutron stars (NSs) will shape our understanding of the physical properties of dense matter under extreme conditions. Binary population synthesis simulations show that forthcoming space-borne gravitational wave detectors may be capable of detecting some tight Galactic double NSs with 10-min orbital periods. Successfully searching for continuous waves from the individual NS in such a close binary demands extremely precise waveform templates considering the interaction between the NS and its companion. Unlike the isolated formation channel, double NS systems from the dynamical formation channel have moderate to high orbital eccentricities. To accommodate these systems, we generalize the analytical waveforms from triaxial nonaligned NSs under spin-orbit coupling derived by Feng et al. [Phys. Rev. D 108, 063035 (2023)] to incorporate the effects of the orbital eccentricity. Our findings suggest that, for binaries formed through isolated binary evolution, the impact of eccentricity on the continuous waves of their NSs can be neglected. In contrast, for those formed through dynamical processes, it is necessary to consider eccentricity, as high-eccentricity orbits can result in a fitting factor of $\lesssim 0.97$ (0.9) within approximately 0.5 (1) to 2 (5) yr of a coherent search (at wave frequencies of 100 and 200 Hz). Once the continuous waves from spinning NSs in tight binaries are detected, the relative measurement accuracy of eccentricity can reach $\mathrm{\Delta }e/e\sim O({10}^{-7})$ for a signal-to-noise ratio of $O(100)$ based on the Fisher information matrix, bearing significant implications for understanding the formation mechanisms of double NS systems.

We investigate the gravitational wave spectrum induced by first-order quantum chromodynamics (QCD) phase transitions, e.g., the confinement-deconfinement phase transition of the pure gluon system and the chiral phase transitions in the quark-meson model and Polyakov quark-meson model. The gravitational wave power spectra are sensitive to the phase transition rate $\beta /H$. All QCD models predict a relatively large phase transition rate in the order of $\beta /H\sim {10}^4$ at high temperature region, and the produced gravitational waves lie in the peak frequency region of ${10}^{-4}–0.01\mathrm{Hz}$, corresponding to an energy spectrum in the range of ${10}^{-8}–{10}^{-7}$, which can be detected by LISA and Taiji. If a high baryon density region is generated through Affleck-Dine baryogenesis or other mechanisms, the baryon chemical potential significantly reduces the phase transition rate, which will drop to the order of $\beta /H\sim {10}^1$, thus leading to the production of nanohertz gravitational waves. Furthermore, there exists a critical quark chemical potential with zero phase transition rate $\beta /H=0$, indicating that the false vacuum will not decay, which supports the formation of primordial quark nuggets in the early Universe.

We investigate the effect of a first-order electroweak phase transition (FOEWPT), which is one of the prerequisites for electroweak baryogenesis, on the thermal relic abundance of the dark matter (DM) that freezes out before the occurrence of the phase transition in the complex singlet scalar extended $Z_3$-invariant type-II seesaw model that can simultaneously provide a DM candidate, explain the nonvanishing neutrino masses and the baryon asymmetry of the Universe. Such a phase transition around the electroweak scale leaves an impact on the relic density due to the release of entropy, particularly for a TeV-scale DM. We thus concentrate on the region of parameter space of the said model, which favors an FOEWPT in the early Universe and for which the DM is heavy such that its freeze-out temperature turns out to be larger than the phase transition temperature. We further study the dependencies of the dilution factor of the DM relic density on the model parameters, the nucleation temperature, the strength and the duration of the phase transition. Such a dilution might retrieve some of the regions of parameter space that were previously ruled out by the measured value of the DM relic density and/or the latest constraints from the DM direct-detection experiments. Furthermore, a direct connection is drawn between the dilution factor and the generation of stochastic gravitational waves as a result of an FOEWPT.