The latest binary black hole population estimates argue for a subpopulation of unequal component mass binaries with spins that are likely small but isotropically distributed. This implies a nonzero probability of detecting spin-induced orbital precession and higher order multipole moments in the observed gravitational-wave signals. In this work we directly calculate the probability for precession and higher-order multipoles in each significant gravitational-wave candidate observed by the LIGO-Virgo-KAGRA collaborations. We find that only one event shows substantial evidence for precession: GW200129_065458, and two events show substantial evidence for higher-order multipoles: GW190412 and GW190814; any evidence for precession and higher-order multipole moments in other gravitational-wave signals is consistent with random fluctuations caused by noise. We then compare our observations with expectations from population models, and confirm that current population estimates from the LIGO-Virgo-KAGRA collaborations accurately predict the number of observed events with significant evidence for precession and higher-order multipoles. In particular, we find that this population model predicts that a binary with significant evidence for precession will occur once in every $\sim 50$ detections, and a binary with significant evidence for higher-order multipoles will occur once in every $\sim 70$ observations. However, we emphasize that since substantial evidence for precession and higher-order multipoles have only been observed in three events, any population model that includes a subpopulation of binaries yielding $\sim 2\%$ of events with detectable precession and higher-order multipole moments will likely be consistent with the data.

Ground-based gravitational wave detectors use laser interferometry to detect the minuscule distance change between test masses caused by gravitational waves. Stray light that scatters back into the interferometer causes transient signals that can cover the same frequency range as a potential gravitational wave signal. This scattered light noise is a potentially limiting factor in current and future detectors thus making it relevant to find new ways to mitigate it. Here, we demonstrate experimentally a technique for the subtraction of scattered light noise from the displacement readout of a Michelson interferometer. It is based on using a balanced homodyne detector at both the symmetric and the antisymmetric port. While we have been able to demonstrate a noise reduction of 13.2 dB, the readout scheme seems to be only limited by the associated noise couplings, i.e., shot noise and the coupling of laser noise. We also discuss challenges for using the dual balanced homodyne detection scheme in more complex interferometer topologies, which could lead to improvements in scattered light noise mitigation of gravitational wave detectors.

We explore the two-body nonleptonic weak decays of ${\mathrm{\Omega }}_c^0$ into final states ${\mathbf{B}}^{(*)}M$ and ${\mathbf{B}}^{(*)}V$, where ${\mathbf{B}}^{(*)}$ denotes an octet (a decuplet) baryon and $M(V)$ represents a pseudoscalar (vector) meson. We employ the topological $SU(3{)}_f$ approach to depict and parametrize the $W$-emission and $W$-exchange processes. We find that the topological parameters can be associated and combined, making them extractable for calculation. Consequently, we explain the partially measured branching fractions relative to $\mathcal{B}({\mathrm{\Omega }}_c^0\to {\mathrm{\Omega }}^{-}{\pi }^{+})$, recombined or kept as the following ratios: $\mathcal{B}({\mathrm{\Omega }}_c^0\to {\mathrm{\Xi }}^{*0}{\overline{K}}^{*0})/\mathcal{B}({\mathrm{\Omega }}_c^0\to {\mathrm{\Omega }}^{-}{\rho }^{+})=0.28\pm 0.11$, $\mathcal{B}({\mathrm{\Omega }}_c^0\to {\mathrm{\Xi }}^{-}{\pi }^{+})/\mathcal{B}({\mathrm{\Omega }}_c^0\to {\mathrm{\Xi }}^0{\overline{K}}^0)=0.10\pm 0.02$, and $\mathcal{B}({\mathrm{\Omega }}_c^0\to {\mathrm{\Omega }}^{-}{K}^{+})/\mathcal{B}({\mathrm{\Omega }}_c^0\to {\mathrm{\Omega }}^{-}{\pi }^{+})=0.06\pm 0.01$. In particular, we present $\mathcal{B}({\mathrm{\Omega }}_c^0\to {\mathrm{\Xi }}^0{\pi }^0)=(2.3\pm 0.2)\times {10}^{-4}$ as half the value of $\mathcal{B}({\mathrm{\Omega }}_c^0\to {\mathrm{\Xi }}^{-}{\pi }^{+})$ in the approximate isospin relation, and highlight potential candidates for testing $SU(3{)}_f$ symmetry breaking.

We uncover two precise interpretations of traditional electroweak fine-tuning (FT) measures that were historically missed. (i) a statistical interpretation: the traditional FT measure shows the change in plausibility of a model in which a parameter was exchanged for the $Z$ boson mass relative to an untuned model in light of the $Z$ boson mass measurement. (ii) an information-theoretic interpretation: the traditional FT measure shows the exponential of the extra information, measured in nats, relative to an untuned model that you must supply about a parameter in order to fit the $Z$ mass. We derive the mathematical results underlying these interpretations, and explain them using examples from weak scale supersymmetry. These new interpretations allow us to rigorously define FT in particle physics and beyond, shed fresh light on the status of extensions to the Standard Model and, lastly, allow us to precisely reinterpret historical and recent studies using traditional FT measures.

We perform the first global QCD analysis of electron-nucleon deep-inelastic scattering and related high-energy data including the beyond the Standard Model $U(1{)}_{B-L}$ gauge boson, $Z^{\prime }$. Contrary to the dark photon case, we find no improvement in the ${\chi }^2$ relative to the baseline result. The finding allows us to place exclusion limits on the coupling constant of the $Z^{\prime }$ with mass in the range $M_{Z^{\prime }}=2$ to 160 GeV.

Nucleophobic axion models, wherein axion couplings to both protons and neutrons are simultaneously suppressed, can relax the stringent constraints from SN 1987A. However, it remains uncertain whether these models maintain their nucleophobic property under the influence of finite baryon density effects. These are especially relevant in astrophysical environments near saturation density, such as supernovae (SNe). In this study, we demonstrate that the nucleophobic solution remains viable also at finite density. Furthermore, we show that the SN axion bound relaxes significantly in nucleophobic models, even when accounting for the integration over the nonhomogeneous environment of the SN core.

Heavy neutral leptons (HNLs), depending on their mass and mixing, can be efficiently produced in meson decays from the target or absorber in short- to medium-baseline accelerator neutrino experiments, leaving detectable signals through their decays inside the neutrino detectors. We show that the currently running ICARUS experiment at Fermilab can reconstruct the HNL mass and explore new HNL parameter space in the mass range of 70–190 MeV. The mass reconstruction is enabled by two ingredients: (i) simple two-body kinematics of HNL production from stopped kaon decays at the NuMI absorber, followed by HNL decay into a charged-lepton pair and neutrino at the detector, and (ii) high resolution of Liquid Argon Time Projection Chamber (LArTPC) detectors in reconstructing final state particles. Our mass reconstruction method is robust under realistic energy resolution and angular smearing of the charged leptons, and is applicable to any LArTPC detector. We also discuss the synergy between ICARUS and future facilities like DUNE near detector and PIP-II beam dump in probing the HNL parameter space.

Some of the most precise measurements of Higgs boson couplings are from the Higgs decays to 4 leptons, where deviations from the Standard Model predictions can be quantified in the framework of the Standard Model effective field theory (SMEFT). In this work, we present a complete next-to-leading order (NLO) SMEFT electroweak calculation of the rate for $H\to {\ell }^{+}{\ell }^{-}Z$ which we combine with the NLO SMEFT result for $Z\to {\ell }^{+}{\ell }^{-}$ to obtain the NLO rate for the $H\to 4$ lepton process in the narrow width approximation. The NLO calculation provides sensitivity to a wide range of SMEFT operators that do not contribute to the rate at lowest order and demonstrates the importance of including correlations between the effects of different operators when extracting limits on SMEFT parameters. We show that the extraction of the Higgs trilinear coupling from the decay $H\to {\ell }^{+}{\ell }^{-}Z,Z\to {\ell }^{+}{\ell }^{-}$ in the narrow width approximation strongly depends on the contributions of other operators that first occur at NLO.

We present a model-independent method to calculate the radiative transition without the momentum extrapolation for the off shell transition factors. The on shell transition factor is directly obtained from the lattice hadronic function. We apply the method to calculate the charmonium radiative transition $J/\psi \to \gamma {\eta }_c$. After a continuous extrapolation under three lattice spacings, we obtain the on shell transition factor as $V(0)=1.90(4)$, where the error is the statistical error that already takes into account the $a^2$ error in the continuous extrapolation. Finally, we determine the branching fraction of $J/\psi \to \gamma {\eta }_c$ as $\mathrm{Br}(J/\psi \to \gamma {\eta }_c)=2.49(11{)}_{\mathrm{lat}}(5{)}_{\exp }\%$, where the second error comes from the uncertainty of $J/\psi$ total decay width 92.6(1.7) keV.

Individual quarks and gluons at small $x$ inside an unpolarized hadron can be regarded as Bell states in which qubits in the spin and orbital angular momentum spaces are maximally entangled. Using the machinery of quantum information science, we generalize this observation to all values $0<x<1$ and describe gluons (but not quarks) as maximally entangled states between a qubit and a qudit. We introduce the conditional probability distribution $P(l^z|s^z)$ of a gluon’s orbital angular momentum $l^z$ given its helicity $s^z$. Restricting to the three states $l^z=0,\pm 1$, which constitute a qutrit, we explicitly compute $P$ as a function of $x$.

Quantum chromodynamics (QCD) with pure imaginary baryon number chemical potential $\mu =i\theta T$, where $T$ is temperature and $\theta$ is a real number, has the Roberge-Weiss periodicity. We study the $\theta$-dependence of the baryon number density and the pressure in the hadron resonance gas model with excluded volume effects of baryons. It is shown that the baryon number density and the pressure are smooth periodic functions of $\theta$ at low or high temperature. However, they have singular behavior at $\theta =(2k+1)\pi$ where $k$ is an integer, when $T\sim 211\mathrm{MeV}$. This temperature is consistent with the Roberge-Weiss transition temperature $T_{\mathrm{RW}}$ obtained by lattice QCD simulations. This singularity can be explained by the dual excluded volume effects in which the roles of pointlike and nonpointlike particles are exchanged each other in the ordinary excluded volume effects. It is also indicated that the excluded volume effect is visible just below $T_{\mathrm{RW}}$ and is directly detectable by the lattice QCD simulation at finite $\theta$. We compare the results with the one obtained by the Polyakov-loop extended Nambu–Jona-Lasinio model.

We present a simple approach to the study of semileptonic $B\to D^{*}\ell {\nu }_{\ell }$ decays based on the angular distributions of the final state particles only. Our approach is model independent and never requires the knowledge of $|V_{cb}|$. By studying such distributions in the case of light leptons, a comparison between results from different datasets from the Belle and BelleII Collaborations and between data and Standard Model calculations is also given for several interesting quantities. A good consistency is observed between some of the experimental results and the theoretical predictions.

Quasinormal modes of rapidly rotating black holes are crucial in understanding the ringdown phase after a merger. While for Kerr black holes these modes have been known for a long time, their calculation has remained a challenge in alternative theories of gravity. We obtain the spectrum of quasinormal modes of rapidly rotating black holes in Einstein-Gauss-Bonnet-dilaton theory without resorting to perturbation theory in the coupling constant. Our approach is based on a spectral decomposition of the linear perturbations of the metric and the scalar field. The quasinormal modes agree excellently with the perturbatively known slow rotation and weak coupling limits. For large coupling, though, the spectrum changes significantly.

Loop quantum cosmology has achieved great successes, in which the polymerization plays a crucial role. In particular, the phase-space-variable-dependent polymerization turns out to be the unique one that leads to consistent quantization of the homogeneous and isotropic universe. However, when applying the same scheme to the quantization of black holes, it meets resistances when the Kantowski-Sachs (KS) gauge is adopted. In this paper, we continue to study the quantum effects of the polymerization near the location that a classical black hole horizon used to be, from the point of view of effective loop quantum gravity in the KS gauge. In particular, we find a phase-space-variable-dependent polymerization scheme that leads to negligible quantum effects near the location of the classical black hole horizon, but it significantly alters the spacetime structure near the origin, so that the classical singularity is finally replaced by a finite and regular transition surface. The final geodesically complete spacetime consists of the regular transition surface that connects a black hole on one side and an antitrapped region on the other side. In the antitrapped region, no white hole horizons are found, and the spacetime is extended to infinity, at which the geometric radius of the two-spheres becomes infinitely large.

We apply machine learning to understand fundamental aspects of holographic duality, specifically the entropies obtained from the apparent and event horizon areas. We show that simple features of only the time series of the pressure anisotropy, namely the values and half-widths of the maxima and minima, the times these are attained, and the times of the first zeroes can predict the areas of the apparent and event horizons in the dual bulk geometry at all times with a fixed maximum length (10) of the input vector. We also argue that the entropy functions are the measures of information that need to be extracted from simple one-point functions to reconstruct specific aspects of correlation functions of the dual state with the best possible approximations.

We investigate, in the framework of linearized quantum gravity, the quantum gravitational interaction between a gravitoelectrically polarizable object and a gravitomagnetically polarizable object. This interaction originates from the coupling between the instantaneous mass quadrupole moment and the mass-current quadrupole moment of the objects, induced by fluctuating gravitoelectric and gravitomagnetic fields in a vacuum. Using leading-order perturbation theory, we derive the explicit expression of the quantum gravitoelectric-gravitomagnetic interaction energy, which shows a distance dependence of $r^{-8}$ in the near regime and $r^{-11}$ in the far regime, where $r$ is the distance between the two objects. Remarkably, this interaction energy is positive, indicating that the force is repulsive. Since interactions between objects polarizable in the same gravitoelectric or gravitomagnetic manner are inherently attractive, for objects which are both gravitoelectrically and gravitomagnetically polarizable, the overall quantum gravitational interaction potential is reduced when the repulsive quantum gravitoelectric-gravitomagnetic interaction is taken into account. However, for two isotropically polarizable objects with identical gravitoelectric and gravitomagnetic polarizabilities and energy level spacing, the repulsive quantum interaction cannot surpass the attractive interactions.

We propose a new method to calculate perturbatively the isospectral Hermitian theory for the $\mathcal{P}\mathcal{T}$-symmetric $i{\varphi }^3$ quantum field theory in $d$ dimensions, whose result is local. The result of the new method in 1 dimension reproduces our previous result in the $i{x}^3$ quantum mechanics, and the new method can be seen as a generalization of our previous method to quantum field theory. We also find the isospectral local Hermitian theory has the same form in all dimensions and differs in coefficients only, and our previous results in quantum mechanics can be used directly to determine the form of the isospectral local Hermitian quantum field theory.

Emergent modified gravity is a post-Einsteinian gravitational theory where spacetime geometry is not fundamental but rather emerges from the gravitational degrees of freedom in a nontrivial way. The specific relationship between geometry and these degrees of freedom is unique for each theory, but it is not predetermined. Instead, it is derived from constraints and equations of motion, relying on key aspects of the canonical formulation of gravity, such as structure functions in Poisson brackets of constraints and covariance conditions. As shown in previous work, these new theories allow for two types of scalar matter coupling: (1) minimal coupling, where the matter equations of motion mirror the Klein-Gordon equation on a curved emergent spacetime, and (2) nonminimal coupling, where the equations deviate from the Klein-Gordon form but still respect covariance. Observable features, such as the quasinormal mode spectrum, can help distinguish between different couplings based on how well their predictions match the data. In this work, the spectra of scalar quasinormal modes for both minimal and nonminimal couplings are derived using the third-order WKB approximation. Significant differences are found between the two cases. Notably, the nonminimal coupling allows for vanishing real and imaginary frequency components, and even opposite-sign values for the imaginary part at sufficiently small mass scales, pointing to potential new physical implications. Finally, the high-frequency QNM spectra in emergent modified gravity are identical to the classical result, up to an overall constant, suggesting that the horizon area spectrum remains equispaced.

Many current models for the gravitational-wave signal from precessing black-hole binaries neglect an asymmetry in the $\pm m$ multipoles. The asymmetry is weak, but is responsible for out-of-plane recoil, which for the final black hole can be several thousand $\mathrm{km}/\mathrm{s}$. In this work we show that the multipole asymmetry is also necessary to accurately measure the black-hole spins. We consider synthetic signals calculated from the numerical relativity surrogate model nrsur7dq4, which includes the multipole asymmetry, and measure the signal parameters using two versions of the same model, one with and one without the multipole asymmetry included. We find that in high signal-to-noise-ratio observations where the spin magnitude and direction can in principle be measured accurately, neglecting the multipole asymmetry can result in biased measurements of these quantities. Measurements of the black-hole masses and the standard aligned-spin combination ${\chi }_{\mathrm{eff}}$ are not in general strongly affected. As an illustration of the impact of the multipole asymmetry on a real signal we consider the LIGO-Virgo-KAGRA observation GW200129_065458, and find that the inclusion of the multipole asymmetry is necessary to identify the binary as unequal mass and a high in-plane spin in the primary.

We report the detection of six new candidate binary black hole (BBH) merger signals in the publicly released data from the second half of the third observing run (O3b) of advanced LIGO and advanced Virgo. The LIGO–Virgo–KAGRA (LVK) Collaboration reported 35 compact binary coalescences in their analysis of the O3b data [Phys. Rev. X 13, 041039 (2023).], with 30 BBH mergers having coincidence in the Hanford and Livingston detectors. We confirm 17 of these for a total of 23 detections in our analysis of the Hanford–Livingston coincident O3b data. We identify candidates using a search pipeline employing aligned-spin quadrupole-only waveforms. Our pipeline is similar to the one used in our O3a coincident analysis [Phys. Rev. D 106, 043009 (2022).], except for a few improvements in the veto procedure and the ranking statistic, and we continue to use an astrophysical probability of one half as our detection threshold, following the approach of the LVK catalogs. Most of the new candidates reported in this work are placed in the upper/lower-mass gap of the black hole mass distribution. We also identify a possible neutron star-black hole merger. We expect these events to help inform the black hole mass and spin distributions inferred in a full population analysis.