Ultralight dark matter (ULDM) is proposed as a theoretical candidate of dark matter particles with masses of approximately ${10}^{-22}\mathrm{eV}$. The interactions between ULDM particles and standard model particles would cause variations in pulse arrival times of millisecond pulsars, which means that the pulsar timing array (PTA) can be used to indirectly detect ULDM. In this Letter, we use the gamma-ray PTA composed of 29 millisecond pulsars observed by the Fermi Large Area Telescope (Fermi-LAT) to test four ULDM effects, including gravitational effects for generalized ULDM with different spin-$0/1$, the fifth-force coupling effect of dark photons, and the modified gravitational effect of the spin-2 ULDM. The gamma-ray pulsar timing is not affected by the ionized interstellar medium and suffers relatively simple noises, unlike that of the radio band. Our work is the first time that the gamma-ray PTA has been used to search for the ULDM. No significant signals of ULDM are found based on the Fermi-LAT PTA for all four kinds of ULDM models. Constraints on ULDM parameters are set with the 95% confidence level, which provides a complementary check of the nondetection of ULDM for radio PTAs and direct detection experiments.

Chiral bosons, or self-dual $p$-form fields, are ubiquitous in string theoretic contexts but are challenging to treat. Lagrangian constructions invariably introduce a complexity be it auxiliary fields or sacrificing Lorentz invariance. In this paper we show how to pass between such different approaches to chiral bosons starting from a Chern Simons point of view to recover formulations of Pasti, Sorokin and Tonin and of Mkrtchyan. This leads to a novel generalization of the latter to include non-Abelian chiral bosons in 2-dimensions, and generalizations to include twisted self-duality which are relevant in T-duality symmetric approaches to string theory. Our approach also shows how global affine symmetries of two- and higher-dimensional chiral bosons emerge from broken Chern-Simons gauge transformations on the boundary.

Using the numerical modular bootstrap, we constrain the space of $1+1\mathrm{d}$ conformal field theories (CFTs) with a finite noninvertible global symmetry described by a fusion category $\mathcal{C}$. We derive universal and rigorous upper bounds on the lightest $\mathcal{C}$-preserving scalar local operator for fusion categories such as the Ising and Fibonacci categories. These numerical bounds constrain the possible robust gapless phases protected by a noninvertible global symmetry, which commonly arise from microscopic lattice models such as the anyonic chains. We also derive bounds on the lightest $\mathcal{C}$-violating local operator. Our bootstrap equations naturally arise from a “slab construction,” where the CFT is coupled to the $2+1\mathrm{d}$ Turaev-Viro topological quantum field theory , also known as the symmetry TFT.

We investigate how the speed of gravitational waves, $c_{\mathrm{GW}}$, can be tested by upcoming black hole ringdown observations. We do so in the context of hairy black hole solutions, where the hair is associated with a new scalar degree of freedom, forecasting that LISA and TianQin will be able to constrain deviations of $c_{\mathrm{GW}}$ from the speed of light at the $\mathcal{O}({10}^{-4})$ level from a single supermassive black hole merger. We discuss how these constraints depend on the nature of the scalar hair, what different aspects of the underlying physics they are sensitive to in comparison with constraints derived from gravitational wave propagation effects, which observable systems will place the most stringent bounds, and that constraints are expected to improve by up to two orders of magnitude with multiple observations. This is especially interesting for dark energy-related theories, where existing bounds from GW170817 need not apply at lower frequencies and where upcoming bounds from lower-frequency missions will therefore be especially powerful. As such, we also forecast analogous bounds for the intermediate-frequency AEDGE and DECIGO missions. Finally, we discuss and forecast analogous black hole ringdown constraints at higher frequencies (so from LVK, the Einstein Telescope and Cosmic Explorer) and in what circumstances they can yield new information on top of existing constraints on $c_{\mathrm{GW}}$. All calculations performed in this paper are reproducible via a companion Mathematica notebook [1].

The scrambling time and its delay are calculated using holography in an asymptotically AdS black hole solution of the gauged Einstein-Maxwell dilaton-axion (EMDA) theory, the dyonic Kerr-Sen-${\mathrm{AdS}}_4$ black hole, perturbed by rotating and charged shock waves along the equator. The leading term of the scrambling time for a black hole with large entropy is logarithmic in the entropy and hence supports the fast scrambling conjecture for this black hole solution, which implies that the system under consideration is chaotic. We also find that the instantaneous minimal Lyapunov index is bounded by $\kappa =2\pi T_H/(1-\mu \mathcal{L})$, which is analogous to the surface gravity but for the rotating shock waves, and becomes closer to equality for the near extremal black hole. For a small value of the AdS scale, we found that the Lyapunov exponent can exceed the bound for a large value of $\mathcal{L}$. Due to the presence of the electric and magnetic charge of the shock waves, we also show that the scrambling process of this holographic system is delayed by a time scale that depends on the charges of the shock waves. The calculations also hold for the ultraspinning version of this black hole. The result of this paper generalizes the holographic calculations of chaotic systems which are described by an EMDA theory in the bulk.

In this paper, we analyze the light rays around a static hairy black hole in Horndeski gravity with the use of ray-tracing procedure. We find that a stronger Horndeski hairy parameter corresponds to larger photon sphere as well as critical impact parameter, and wider ranges of photon ring and lensed ring emissions. These influences can be robustly interpreted from the shape of the effective potential of the photon’s radial motion. Based on the distribution of the light rays, we then investigate the optical appearances of the Horndeski hairy black hole surrounded by various thin accretions. First, we consider that the Horndeski hairy black hole is illuminated by the optically and geometrically thin accretion disk. We carefully clarify the contributions from the direct, lensed ring and photon ring intensities to the total observed intensity via the transfer function, which is rarely discussed in this scenario. We find that the Horndeski hair has significant influences on both shadow size and distributions of direct, lensed ring and photon ring brightness in three standard emission profiles. As a result, the rings and images of Horndeski hairy black hole and the origination of their brightness differentiate from those of Schwarzschild black hole (SBH) when viewed in face-on orientation. Then, when the Horndeski hairy black hole is illuminated by thin spherical accretions, the hairy black hole’s shadow surrounded by a bright ring is larger than that of SBH, but the brightness of ring is fainter. Similar to that of SBH, the size of hairy black hole shadow does not change as the radial moving of the spherical accretion, and the brightness for the infalling accretion is fainter than that for the static accretion due to the Doppler effect. Therefore, we argue that the black hole image consisting of the shadow and accretion construction could, in theory, reflect the observational differences between the Horndeski hairy black hole and SBH.

We present a numerical-relativity simulation of a black hole-neutron star merger in scalar-tensor (ST) gravity with binary parameters consistent with the gravitational wave event GW200115. In this exploratory simulation, we consider the Damour-Esposito-Farèse extension to Brans-Dicke theory, and maximize the effect of spontaneous scalarization by choosing a soft equation of state and ST theory parameters at the edge of known constraints. We extrapolate the gravitational waves, including tensor and scalar (breathing) modes, to future null-infinity. The numerical waveforms undergo $\sim 22$ wave cycles before the merger, and are in good agreement with predictions from post-Newtonian theory during the inspiral. We find the ST system evolves faster than its general-relativity (GR) counterpart due to dipole radiation, merging a full gravitational-wave cycle before the GR counterpart. This enables easy differentiation between the ST waveforms and GR in the context of parameter estimation. However, we find that dipole radiation’s effect may be partially degenerate with the NS tidal deformability during the late inspiral stage, and a full Bayesian analysis is necessary to fully understand the degeneracies between ST and binary parameters in GR.

Scalar fields coupled to dark matter by conformal or disformal transformations give rise to a general class of scalar-tensor theories which leads to a rich phenomenology in a cosmological setting. While this possibility has been studied comprehensively in the literature for scalar fields, the vector case has hardly been treated. Hence, we build models based on vector fields which are conformally and disformally coupled to dark matter and explicitly derive the general covariant form of the interaction term in an independent way of the gravity theory, whereby this result can be applied to general vector-tensor theories. For concreteness, the standard Proca theory with a vector exponential potential is taken to describe the vector-tensor sector, and some specific coupling functions are assumed to study the cosmological background dynamics using dynamical system techniques. As a first examination about instabilities issues, we derive general conditions to avoid classical instabilities in a more general setup of the theory. Interestingly, despite choosing such a minimalist form for the underlying theory, the parameter space is considerably enriched compared to the uncoupled case due to the novel interactions, leading to new branches of solutions for the vector equation of motion. Thus, different trajectories can exist in phase space depending on the coupling parameters associated to the conformal and disformal functions. From here, new emerging vector-dark matter scaling solutions, and renewed stable attractor points are found to drive the late-time accelerated expansion of the Universe. Additionally, numerical calculations are performed to investigate more quantitatively the impact of the conformal and disformal couplings on the cosmological background evolution. These effects depend essentially on the strength of the coupling parameters and, in some specific cases, on their associated signs. In all the cases studied we find that the coupling of the vector field to dark matter can significantly affect the cosmological dynamics during different stages of the evolution of the Universe.

We explore the effect magnetic fields have on self-gravitating accretion disks around spinning black holes via numerical evolutions in full dynamical magnetohydrodynamic spacetimes. The configurations we study are unstable to the Papaloizou-Pringle instability (PPI). PPI-saturated accretion tori have been shown to produce gravitational waves, detectable to cosmological distances by third-generation gravitational wave (GW) observatories. While the PPI operates strongly for purely hydrodynamic disks, the situation can be different for disks hosting initially small magnetic fields. Evolutions of disks without self-gravity in fixed black hole (BH) spacetimes have shown that small seed fields can initiate the rapid growth of the magneto-rotational instability (MRI), which then strongly suppresses the PPI. Since realistic astrophysical disks are expected to be magnetized, PPI-generated GW signals may be suppressed as well. However, it is unclear what happens when the disk self-gravity is restored. Here, we study the impact of magnetic fields on the PPI-saturated state of a self-gravitating accretion disk around a spinning BH ($\chi =0.7$) aligned with the disk angular momentum, as well as one around a nonspinning BH. We find the MRI is effective at reducing the amplitude of PPI modes and their associated GWs, but the systems still generate GWs. Estimating the detectability of these systems across a wide range of masses, we show that magnetic fields reduce the maximum detection distance by Cosmic Explorer from 300 Mpc (in the pure hydrodynamic case) to 45 Mpc for a $10M_{\odot }$ system, by LISA from 11500 to 2700 Mpc for a $2\times {10}^5{M}_{\odot }$ system, and by DECIGO from $z\approx 5$ down to $z\approx 2$ for a $1000M_{\odot }$ system.

The discrepancy between the value of Hubble constant measured by cosmic microwave background observations and local low-redshift based observations has proposed many solutions that require the existence of physics beyond the Standard Model (SM). One of the interesting solutions is based on considering the strong self-interaction between SM neutrinos through an additional scalar/vector mediator. Interestingly, the strong self-interaction between SM neutrinos also play an important role in obtaining KeV-sterile neutrino as a viable dark matter candidate through the famous Dodelson-Widrow mechanism. In this work, we have tried to find the synergy between the parameter space of active-sterile neutrino mixing vs mass of sterile neutrino allowed by Hubble tension solution and the requirement of getting KeV-sterile neutrino as DM candidate. Interestingly, we get a large amount of parameter space that is consistent with both the requirements and also free from x-ray constraints. Finally, we have embedded this scenario in a consistent supersymmetric model of particle physics. In this framework, we have shown that the value of sterile neutrino mass, SM neutrino mass, and the required mixing angle can be naturally obtained by considering the supersymmetry breaking scale to be around $\mathcal{O}(10)\mathrm{TeV}$. Thus, it would give an interesting testing ground for supersymmetry as well as signatures of warm dark matter.

Resolving individual gravitational waves from tens of millions of double white dwarf (DWD) binaries in the Milky Way is a challenge for future space-based gravitational wave detection programs. By using previous data to define the priors for the next search, we propose an accelerated approach of searching the DWD binaries, and demonstrate its efficiency based on the GBSIEVER detection pipeline. Compared to the traditional GBSIEVER method, our method can obtain $\sim 50\%$ of sources with 2.5% of the searching time for LDC1-4 data. In addition, we find that both methods have a similar ability to detect the Milky Way structure by their confirmed sources. The relative error of distance and chirp mass is about 20% for DWD binaries whose gravitational wave frequency is higher than $4\times {10}^{-3}\mathrm{Hz}$, even if they are close to the Galactic Center. Finally, we propose a signal-to-noise ratio (SNR) threshold for LISA to confirm the detection of DWD binaries. The threshold should be 16 when the gravitational wave frequency is lower than $4\times {10}^{-3}\mathrm{Hz}$ and 9 when the frequency range is from $4\times {10}^{-3}$ to $1.5\times {10}^{-2}\mathrm{Hz}$.

We analyze quasi-two-body charmless $B$ decays $B_{(s)}\to P_{1}V\to P_1{P}_2{P}_3$ with $V$ representing a vector resonant, and $P_{1,2,3}$ as a light pseudoscalar meson, pion, kaon, or ${\eta }^{(\prime )}$. The intermediate processes $B_{(s)}\to P_{1}V$ are calculated in the factorization-assisted topological-amplitude approach and the vector resonant effects are described by the Breit-Wigner propagator, which successively decay to $P_1{P}_2$ via strong interaction. Taking into account of all vector resonances in ground state, $\rho ,K^{*},\omega ,\varphi$, we present the related branching fractions, and calculate the virtual effects for $B_{(s)}\to \pi ,K(\rho ,\omega \to )KK$. We also predict direct $CP$ asymmetries of three-body $B$ decay modes with $\rho ,K^{*}$ resonances as intermediate states. Our predicted branching fractions of decay modes dominated by the color-favored tree diagram or the color-favored penguin diagram are consistent with the perturbative QCD approach’s predictions as well as the QCD factorization approach. While for those nonperturbative contribution dominated decay modes, the branching ratios in this work are in better agreement with current experimental data than the perturbative QCD (PQCD) predictions and the QCD factorization results due to their shortage of the nonperturbative contributions or $1/m_b$ power corrections. Many of the decays channels, especially for direct $CP$ asymmetries, are waiting for the future experiments.

We perform a study of the new physics effects in semileptonic flavour changing neutral current (FCNC) processes within a low-energy approximation of the anomaly-free supersymmetic extension of the standard model (SM) with additional $Z^{\prime }$ vector field. The key feature of the model is the nondiagonal structure of $Z^{\prime }$ couplings to fermions, which is parametrized by few new-physics parameters in addition to well-known mixing matrices for quarks and leptons in the SM. We not only consider $CP$-conserving scenarios with real parameters, but also account for possible $CP$ violation due to new physical weak phases. We analyze the dependence of the $b\to s$ observables on the parameters together with correlations between the observables predicted in the model. Special attention is paid to possible enhancement of $B\to K^{(*)}\nu \overline{\nu }$ rates and to $CP$-odd angular observables in $B\to K^{*}ll$ decays.

In this paper, we have presented a comprehensive study of Lorentz invariance violation (LIV) in the context of the atmospheric neutrino experiment ICAL and the long-baseline experiments T2HK and DUNE. Our study consists of the full parameter space of the LIV parameters, i.e., six $CPT$-violating LIV parameters ($a_{\alpha \beta }$) and six $CPT$-conserving LIV parameters ($c_{\alpha \beta }$). In this study, our objective is to calculate the upper bound on all the LIV parameters with respect to the individual experiments as well as their combination. Our results show that DUNE gives the best sensitivity for the parameters $a_{ee}$, $a_{e\mu }$, $a_{e\tau }$, and $a_{\mu \tau }$ in its 7 years of running, whereas ICAL gives the best sensitivity on $a_{\mu \mu }$, $a_{\mu \tau }$, $c_{ee}$, $c_{\mu \mu }$, $c_{\tau \tau }$, and $c_{\mu \tau }$ in its 10 years of running. For $a_{\tau \tau }$, the sensitivities of DUNE and ICAL are almost same. The combination of T2HK, DUNE, and ICAL gives the best sensitivity for $a_{e\mu }$ and $a_{ee}$ with respect to all the existing bounds in the literature. For the $CPT$-even diagonal parameters $c_{ee}$ and $c_{\mu \mu }$, our work provides the first-ever bounds.

In this work, we extend the resummation for the thrust distribution in Higgs decays up to the fifth logarithmic order. We show that one needs the accurate values of the three-loop soft functions for reliable predictions in the back-to-back region. This is especially true in the gluon channel, where the soft function exhibits poor perturbative convergence.

Recently, we introduced caloflow, a high-fidelity generative model for geant4 calorimeter shower emulation based on normalizing flows. Here, we present caloflow v2, an improvement on our original framework that speeds up shower generation by a further factor of 500 relative to the original. The improvement is based on a technique called probability density distillation, originally developed for speech synthesis in the machine learning literature, and which we develop further by introducing a set of powerful new loss terms. We demonstrate that caloflow v2 preserves the same high fidelity as the original using qualitative (average images, histograms of high-level features) and quantitative (classifier metric between geant4 and generated samples) measures. The result is a generative model for calorimeter showers that matches the state of the art in speed (a factor of ${10}^4$ faster than geant4) and greatly surpasses the previous state of the art in fidelity.

We introduce caloflow, a fast detector simulation framework based on normalizing flows. For the first time, we demonstrate that normalizing flows can reproduce many-channel calorimeter showers with extremely high fidelity, providing a fresh alternative to computationally expensive geant4 simulations, as well as other state-of-the-art fast simulation frameworks based on generative adversarial networks (GANs) or variational autoencoders (VAEs). In addition to the usual histograms of physical features and images of calorimeter showers, we introduce a new metric for judging the quality of generative modeling: the performance of a classifier trained to differentiate real from generated images. We show that GAN-generated images can be identified by the classifier with nearly 100% accuracy, while images generated from caloflow are better able to fool the classifier. More broadly, normalizing flows offer several advantages compared to other state-of-the-art approaches (GANs and VAEs), including tractable likelihoods, stable and convergent training, and principled model selection. Normalizing flows also provide a bijective mapping between data and the latent space, which could have other applications beyond simulation, for example, to detector unfolding.

We present a study of the $X(3872)$ lineshape in the decay $B\to X(3872)K\to D^0{\overline{D}}^{*0}K$ using a data sample of $772\times {10}^{6}B\overline{B}$ pairs collected at the $\mathrm{\Upsilon }(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. The peak near the threshold in the $D^0{\overline{D}}^{*0}$ invariant mass spectrum is fitted using a relativistic Breit-Wigner lineshape. We determine the mass and width parameters to be $m_{\mathrm{BW}}=3873.71_{-0.50}^{+0.56}(\mathrm{stat})\pm 0.13(\mathrm{syst})\mathrm{MeV}/c^2$ and ${\mathrm{\Gamma }}_{\mathrm{BW}}={5.2}_{-1.5}^{+2.2}(\mathrm{stat})\pm 0.4(\mathrm{syst})\mathrm{MeV}$, respectively. The branching fraction is found to be $\mathcal{B}(B^{+}\to X(3872)K^{+})\times \mathcal{B}(X(3872)\to D^0{\overline{D}}^{*0})=(0.97_{-0.18}^{+0.21}(\mathrm{stat})\pm 0.10(\mathrm{syst}))\times {10}^{-4}$. The signal from $B^0$ decays is observed for the first time with $5.2\sigma$ significance, and the ratio of branching fractions between charged and neutral $B$ decays is measured to be $\mathcal{B}(B^0\to X(3872)K^0)/\mathcal{B}(B^{+}\to X(3872)K^{+})={1.34}_{-0.40}^{+0.47}(\mathrm{stat}{)}_{-0.12}^{+0.10}(\mathrm{syst})$. The peak is also studied using a Flatté lineshape. We determine the lower limit on the $D{\overline{D}}^{*}$ coupling constant $g$ to be 0.075 at 95% credibility in the parameter region where the ratio of $g$ to the mass difference from the $D^0{\overline{D}}^{*0}$ threshold is equal to $-15.11{\mathrm{GeV}}^{-1}$, as measured by LHCb.

We report measurements of the branching fraction and $CP$ asymmetry in $B^0\to {\pi }^0{\pi }^0$ decays reconstructed at Belle II in an electron-positron collision sample containing $198\times {10}^{6}B\overline{B}$ pairs. We measure a branching fraction $\mathcal{B}(B^0\to {\pi }^0{\pi }^0)=(1.38\pm 0.27\pm 0.22)\times {10}^{-6}$ and a $CP$ asymmetry ${\mathcal{A}}_{CP}(B^0\to {\pi }^0{\pi }^0)=-0.14\pm 0.46\pm 0.07$, where the first uncertainty is statistical and the second is systematic.

We propose a theory to systematically construct a complete set of on-shell effective operator bases involving massive particles with any spins. The amplitude bases involving massive fields can be factorized into two charged and neutral parts under the little groups of massive particles, respectively. The complete bases of these two parts can be constructed by the Young diagrams of Lorentz subgroup $SU(2{)}_r$ and global symmetry $U(N)$ ($N$ is the number of external particles), respectively, without any redundancies. The corresponding effective field theory bases with the lowest dimension can be obtained by eliminating the linear correlation bases from a complete but redundant set of bases with all possible polarization tensors. Based on this theory, the amplitude bases involving identical particles can be constructed by a matrix projection method. A generic massive effective field theory can thus be constructed automatically by computer programs.