The effective Hamiltonians for chiral supersymmetric gauge theories at small spatial volume are generalizations of the Hamiltonians describing the motion of a scalar or a spinor particle in a field of Dirac monopoles (we are dealing in fact with a certain lattice of monopoles supplemented with a periodic singular potential). The gauge fields in such Hamiltonians belong to the Cartan subalgebras of the corresponding gauge algebras. Such a construction exists for all groups admitting complex representations, i.e., for $SU(N\ge 3)$, $Spin(4n+2)$ with $n\ge 1$ and $E_6$. We give explicit expressions for these Hamiltonians for $SU(3)$, $SU(4)\simeq Spin(6)$ and for $SU(5)$. The simplified version of such a Hamiltonian, deprived of fermion terms, of the extra scalar potential and when only one node of the lattice is taken into consideration, describe a $3r$-dimensional motion ($r$ being the rank of the group) in the field what we call a “Cartan monopole.” As is the case for the ordinary monopole, the Lagrangian of this system enjoys gauge symmetry, rotational symmetry, and the parameter, generalizing the notion of magnetic charge for Cartan monopoles, is quantized.

Nearly all template-based gravitational wave (GW) searches only include the quasicircular quadrupolar modes of the signals in their templates. Including additional degrees of freedom in the GW templates corresponding to higher-order harmonics, orbital precession, or eccentricity is challenging because: (i) the size of template banks and the matched-filtering cost increases significantly with the number of degrees of freedom, (ii) if these additional degrees are not included properly, the search can lose sensitivity overall (due to an increase in the rate of background triggers). Here, we focus on including aligned-spin higher harmonics in GW search templates. We use a new mode-by-mode filtering approach, where we separately filter GW strain data with three harmonics [namely $(\ell ,|m|)=(2,2)$, (3, 3) and (4, 4)]. This results in an increase in the matched-filtering cost by only a factor of 3 compared to that of a (2, 2)-only search. We develop computationally cheap trigger-ranking statistics to optimally combine the different signal-to-noise ratios (SNR) time series from different harmonics, which ensure only physically allowed combinations of the different harmonics are triggered on. We use an empirical template-dependent background model in our ranking statistic to account for non-Gaussian transients. In addition, we develop a tool called band eraser which specifically excises narrow time-varying noisy bands in time-frequency space (without having to excise entire time chunks in the data). New GW candidate events that we detect using our IAS-HM search pipeline and the details of our template banks are discussed in accompanying papers [D. Wadekar et al., arXiv:2312.06631] and [D. Wadekar et al., arXiv:2310.15233], respectively. Apart from higher harmonics, we expect our methodology to also be useful for cheap and optimal searches including orbital precession and eccentricity in GW waveforms.

We investigate the use of harmonic analysis techniques to perform measurements of the angular power spectrum on mock pulsar timing data for an isotropic stochastic gravitational-wave background (SGWB) with a dimensionless strain amplitude $A_{\mathrm{gw}}=2\times {10}^{-15}$ and spectral index ${\gamma }_{\mathrm{gw}}=13/3$. We examine the sensitivity of our harmonic analysis to the number of pulsars (50, 100, and 150) and length of pulsar observation time (10, 20, and 30 years) for an isotropic distribution of pulsars. We account for intrinsic pulsar red noise and use an average value of white noise of $\sim 100\mathrm{ns}$. We are able to detect the quadrupole for all our mock harmonic analyses, and for 150 pulsars observed for 30 years we are able to detect up to the $\ell =5$ multipole. We provide linear scaling relationships for the SGWB amplitude, the quadrupole, and $\ell =3$ as a function of pulsar observation time and number of pulsars. We estimate the sensitivity of our harmonic approach to deviations of general relativity that produce subluminal GW propagation speeds.

Choptuik’s critical phenomena in general relativity is revisited in the affine-null metric formulation of Einstein’s equations for a massless scalar field in spherical symmetry. Numerical solutions are obtained by evolution of initial data using pseudospectral methods. The underlying system consists of differential equations along the outgoing null rays which can be solved in sequential form. A new two-parameter family of initial data is presented for which these equations can be integrated analytically. Specific choices of the initial data parameters correspond to either an asymptotically flat null cone, a black hole event horizon or the singular interior of a black hole. Our main focus is on the interior features of a black hole, for which the affine-null system is especially well adapted. We present both analytic and numerical results describing the geometric properties of the apparent horizon and final singularity. Using a regridding technique for the affine parameter, numerical evolution of initially asymptotically flat supercritical data can be continued inside the event horizon and track the apparent horizon up to the formation of the final singularity.

Using numerical methods, we examine, under a Gowdy symmetry assumption, the dynamics of nonlinearly perturbed Friedmann-Lemaître-Robertson-Walker (FLRW) fluid solutions of the Einstein-Euler-scalar field equations in the contracting direction for linear equations of state $p=K\rho$ and sound speeds $0\le K<1/3$. This article builds upon the numerical work from Beyer et al. [Phys. Rev. D 107, 104030 (2023)] in which perturbations of FLRW solutions to the Einstein-Euler equations with positive cosmological constant in the expanding time direction were studied. The numerical results presented here confirm that the instabilities observed in previous work [Phys. Rev. D 107, 104030 (2023), Lett. Math. Phys. 113, 102 (2023).] for $1/3<K<1$, first conjectured to occur in the expanding direction by Rendall [Ann. Henri Poincaré 5, 1041 (2004)], are also present in the contracting direction over the complementary parameter range $0\le K<1/3$. Our numerical solutions show that the fractional density gradient of the nonlinear perturbations develop steep gradients near a finite number of spatial points and become unbounded toward the big bang. This behavior, and in particular the characteristic profile of the fractional density gradient near the big bang, is strikingly similar to what was observed in the expanding direction near timelike infinity by Beyer et al. [Phys. Rev. D 107, 104030 (2023)].

In this paper, we establish that a four-dimensional static vacuum asymptotically flat spacetime containing a massive particle sphere is isometric to the Schwarzschild spacetime. Our results expand upon existing uniqueness theorems for static vacuum asymptotically flat spacetimes, which focus on scenarios featuring event horizons or photon spheres. Similarly to the uniqueness theorems concerning photon spheres or event horizons, only a single massive particle sphere is sufficient to obtain a unique solution. However, in contrast to previous theorems, our result leads to the existence of an entire spacetime foliation sliced by a set of massive particle spheres spanning various energies.

We construct a general class of modified Ellis-Bronnikov wormholes, where one asymptotic Minkowski region is replaced by a bounded 2-sphere core, characterized by an asymptotic finite areal radius. We pursue an in-depth analysis of the resulting geometry, outlining that geodesic completeness is also guaranteed when the area function asymptotically shrinks to zero. Moreover, we perform an analysis of the circular orbits present in our model and conclude that stable circular orbits are allowed in the bounded region. As a consequence, a stable light ring may exist in the inner region and trapped orbits may appear within this bounded region. Such internal structure suggests that the bounded region can trap perturbations. Then, we study the evolution of scalar perturbations, bringing out how these geometric configurations can in principle affect the time-domain profiles of quasinormal modes, pointing out the distinctive features with respect to other black hole or wormhole geometries.

Inspired by the recent discovery of a violation of strong cosmic censorship (SCC) for the near-extremal Reissner-Nordström black holes in de Sitter space (RN-dS), we investigate if the weak cosmic censorship conjecture (WCCC) can also be violated in RN-dS with a fixed cosmological constant. Our method is based on the recent formulation of examining WCCC by the constraint of the second law, which in this case requires the sum of areas of the event and cosmic horizons cannot decrease during the infall process of Wald’s gedanken experiment. We find that the WCCC can be violated for the near-extremal RN-dS in some regimes of second-order perturbation of field configurations. Given the charge parameter of RN-dS, we can find the lowest value of the subextremality parameter, beyond which the WCCC holds. Our results imply that there might be possible correlations between the violation of SCC and WCC. Because of a lack of an unambiguous relation between the gravitational mass and matter’s kinematic mass in asymptotically de Sitter space, we cannot compare the corresponding regimes of parameter space for the violations of SCC and WCCC. We also discuss the subtlety in formulating the first- and second-law approaches to examine WCCC.

Recent discoveries of large halos of stars and dark matter around some of the lowest mass galaxies defy expectations that dwarf galaxies should be small and dense. Here we find large halos are a general feature of the well known dwarfs orbiting the Milky Way and also for the isolated dwarfs in the Local Group. Furthermore, these halos are seen to surround a dense core within each dwarf, with a clear density transition visible between the core and the halo at a radius of $\simeq 1.0\mathrm{kpc}$. This common core-halo structure is hard to understand for standard heavy particle dark matter where featureless, concentrated profiles are predicted, whereas dark matter as a Bose-Einstein condensate, $\psi \mathrm{DM}$, naturally accounts for the observed profiles, predicting a dense soliton core in every galaxy surrounded by a tenuous halo of interfering waves. We show that the stellar profiles are accurately fitted by the core-halo structure of $\psi \mathrm{DM}$, with only one fixed parameter, the boson mass. We also find independent consistency with the stellar velocity dispersions measured in these dwarf galaxies, which peak at the core radius and fall in the halo, at a level consistent with a boson mass of $\simeq 1.5\times {10}^{-22}\mathrm{eV}$, based on independent dynamical work. Hence, dark matter comprised of light bosons, such as the axions generic in string theory, provides a compelling solution for the structure of dwarf galaxies with stars that simply trace the dark matter profile of a Bose-Einstein condensate.

We study how Abelian-gauge-field production during inflation affects scalar perturbations in the case when the gauge field interacts with the inflaton directly (by means of generic kinetic and axial couplings) and via gravity. The homogeneous background solution is defined by self-consistently taking into account the backreaction of the gauge field on the evolution of the inflaton and the scale factor. For the perturbations on top of this background, all possible scalar contributions coming from the inflaton, the metric, and the gauge field are considered. We derive a second-order differential equation for the curvature perturbation, $\zeta$, capturing the impact of the gauge field, both on the background dynamics and on the evolution of scalar perturbations. The latter is described by a source term in the $\zeta$ equation, which is quadratic in the gauge-field operators and leads to non-Gaussianities in the curvature perturbations. We derive general expressions for the induced scalar power spectrum and bispectrum. Finally, we apply our formalism to the well-known case of axion inflation without backreaction. Numerical results show that, in this example, the effect of including metric perturbations is small for values of the gauge-field production parameter $\xi >3$. This is in agreement with the previous results in the literature. However, in the region of smaller values, $\xi \lesssim 2$, our new results exhibit order-of-unity deviations when compared to previous results.

The Simons Observatory (SO), due to start full science operations in early 2025, aims to set tight constraints on inflationary physics by inferring the tensor-to-scalar ratio $r$ from measurements of cosmic microwave background (CMB) polarization $B$-modes. Its nominal design including three small-aperture telescopes (SATs) targets a precision $\sigma (r=0)\le 0.003$ without delensing. Achieving this goal and further reducing uncertainties requires a thorough understanding and mitigation of other large-scale $B$-mode sources such as Galactic foregrounds and weak gravitational lensing. We present an analysis pipeline aiming to estimate $r$ by including delensing within a cross-spectral likelihood, and demonstrate it for the first time on SO-like simulations accounting for various levels of foreground complexity, inhomogeneous noise and partial sky coverage. As introduced in an earlier SO delensing paper, lensing $B$-modes are synthesized using internal CMB lensing reconstructions as well as Planck-like cosmic infrared background maps and LSST-like galaxy density maps. We then extend SO’s power-spectrum-based foreground-cleaning algorithm to include all auto- and cross-spectra between the lensing template and the SAT $B$-modes in the likelihood function. This allows us to constrain $r$ and the parameters of our foreground model simultaneously. Within this framework, we demonstrate the equivalence of map-based and cross-spectral delensing and use it to motivate an optimized pixel-weighting scheme for power spectrum estimation. We start by validating our pipeline in the simplistic case of uniform foreground spectral energy distributions. In the absence of primordial $B$-modes, we find that the $1\sigma$ statistical uncertainty on $r$, $\sigma (r)$, decreases by 37% as a result of delensing. Tensor modes at the level of $r=0.01$ are successfully detected by our pipeline. Even when using more realistic foreground models including spatial variations in the dust and synchrotron spectral properties, we obtain unbiased estimates of $r$ both with and without delensing by employing the moment-expansion method. In this case, uncertainties are increased due to the higher number of model parameters, and delensing-related improvements range between 27% and 31%. These results constitute the first realistic assessment of the delensing performance at SO’s nominal sensitivity level.

We explore the 21-cm signal in our Universe containing inhomogeneous matter distribution at considerably large scales. Employing Buchert’s averaging procedure in the context of a model of spacetime with multiple inhomogeneous domains, we evaluate the effect of our model parameters on the observable 21-cm signal brightness temperature. Our model parameters are constrained through the Markov chain Monte Carlo method using the Union 2.1 supernova Ia observational data. We find that a significant dip in the brightness temperature compared to the $\mathrm{\Lambda }$ cold dark matter prediction could arise as an effect of the inhomogeneities present in the Universe.

Gravitational waves (GWs) induce correlated perturbations to the arrival times of pulses from an array of galactic millisecond pulsars. The expected correlations, obtained by averaging over many pairs of pulsars having the same angular separation (pulsar averaging) and over an ensemble of model universes (ensemble averaging), are described by the Hellings and Downs curve. As shown by Allen [Phys. Rev. D 107, 043018 (2023)], the pulsar-averaged correlation will not agree exactly with the expected Hellings and Downs prediction if the gravitational-wave sources interfere with one another, differing instead by a “cosmic variance” contribution. The precise shape and size of the cosmic variance depends on the statistical properties of the ensemble of universes used to model the background. Here, we extend the calculations of the cosmic variance for the standard Gaussian ensemble to an ensemble of model universes which collectively has rotationally invariant correlations in the GW power on different angular scales (described by an angular power spectrum, $C_l$ for $l=0,1,\dots$.). We obtain an analytic form for the cosmic variance in terms of the $C_l$’s and show that for realistic values $C_l/C_0\lesssim {10}^{-3}$, there is virtually no difference in the cosmic variance compared to that for the standard Gaussian ensemble (which has a zero angular power spectrum).

Gravitational waves (GWs) influence the arrival times of radio signals coming from pulsars. Here, we investigate the harmonic space approach to describing a pulsar’s response to GWs. We derive and discuss the “diagonalized form” of the response, which is a sum of spin-2-weighted spherical harmonics of the GW direction multiplied by normal (spin-weight 0) spherical harmonics of the pulsar direction. We show how this allows many useful objects, for example, the Hellings and Downs two-point function, to be easily calculated. The approach also provides a clear description of the gauge dependence. We then employ this harmonic approach to model the effects of angular correlations in the sky locations of GW sources (sometimes called “statistical isotropy”). To do this, we construct ensembles made up of many Gaussian subensembles. While each of the individual subsensembles breaks rotational invariance, the full ensemble is rotationally invariant. Using harmonic techniques, we compute the cosmic covariance and the total covariance of the Hellings and Downs correlation in these models. The results may be used to assess the impact of angular source correlations on the Hellings and Downs correlation, and for optimal reconstruction of the Hellings and Downs curve in models where GW sources have correlated sky locations.

We study the possibility of generating dark matter (DM) and baryon asymmetry of the Universe (BAU) simultaneously in an asymmetric DM framework, which also alleviates the small-scale structure issues of cold DM. While the thermal relic of such self-interacting DM remains underabundant due to efficient annihilation into light mediators, a nonzero asymmetry in the dark sector can lead to the survival of the required DM in the Universe. The existence of a light mediator leads to the required self-interactions of DM at small scales while keeping DM properties similar to cold DM at large scales. It also ensures that the symmetric DM component annihilates away, leaving the asymmetric part in the spirit of cogenesis. The particle physics implementation is done in canonical seesaw models of light neutrino mass, connecting it to the origin of DM and BAU. In particular, we consider type-I and type-III seesaw origin of neutrino mass for simplicity and minimality of the field content. We show that the desired self-interactions and relic of DM together with BAU while satisfying relevant constraints lead to strict limits on DM mass $\mathcal{O}(\mathrm{GeV})\lesssim M_{\mathrm{DM}}\lesssim 460\mathrm{GeV}$. In spite of being a high-scale seesaw, the models remain verifiable in different experiments, including direct and indirect DM searches as well as colliders.

We consider a $U(1)$ gauge theory on $M^4\times T^4$ with background magnetic fluxes. We show that a theory including arbitrary fluxes can always be studied in a theory involving only diagonal fluxes by appropriate coordinate transformations. It is found that the number of independent magnetic fluxes is equal to the rank of the classical value of the field strength matrix, $\mathrm{rank}⟨F⟩$. The number of massless zero modes induced from extra components of higher-dimensional gauge field (Wilson-line scalar field) is also determined by $\mathrm{rank}⟨F⟩$. We explicitly confirm that the quantum corrections due to the matter fermion to the squared mass of the Wilson-line scalar field cancel out at the one-loop level. For this purpose, we derive the fermion mass spectrum on $M^4\times T^4$ with arbitrary fluxes. By taking the flux diagonal basis, creation and annihilation operators for Kaluza-Klein quantum numbers are defined appropriately. Our results are easily generalized to the case of $M^4\times T^{2n}(n\ge 3)$.

We investigate the possibility of using the Short-Baseline Near Detector (SBND) at Fermilab to constrain lepton flavor violating decays of pions and kaons. We study how to leverage SBND-PRISM, the use of the neutrino beam angular spread to mitigate systematic uncertainties, to enhance this analysis. We show that SBND-PRISM can put stringent limits on the flavor violating branching ratios $\mathrm{BR}({\pi }^{+}\to {\mu }^{+}{\nu }_e)=8.9\times {10}^{-4}$, $\mathrm{BR}({\mathrm{K}}^{+}\to {\mu }^{+}{\nu }_e)=3.2\times {10}^{-3}$, improving previous constraints by factors 9 and 1.25, respectively. We also estimate the SBND-PRISM sensitivity to lepton number violating decays, $\mathrm{BR}({\pi }^{+}\to {\mu }^{+}{\overline{\nu }}_e)=2.1\times {10}^{-3}$ and $\mathrm{BR}({\mathrm{K}}^{+}\to {\mu }^{+}{\overline{\nu }}_e)=7.4\times {10}^{-3}$, though not reaching previous Big European Bubble Chamber limits. Last, we identify several ways how the SBND collaboration could improve this analysis.

We demonstrate that gauge-equivariant pooling and unpooling layers can perform as well as traditional restriction and prolongation layers in multigrid preconditioner models for lattice QCD. These layers introduce a gauge degree of freedom on the coarse grid, allowing for the use of explicitly gauge-equivariant layers on the coarse grid. We investigate the construction of coarse-grid gauge fields and study their efficiency in the preconditioner model. We show that a combined multigrid neural network using a Galerkin construction for the coarse-grid gauge field eliminates critical slowing down.

We develop a systematic approach to analyze polarization correlations of two baryons $B_1{\overline{B}}_2$ produced in the electron-positron annihilation process. With spin density matrices for arbitrary spin particles established in the standard, the Cartesian, and the helicity forms, we provide analyses of polarization correlations for two baryons with various spin combinations. This framework can be applied to determine the spin and the parity of excited baryons, and therefore offers opportunities for the investigation of baryon spectrum and transition form factors in present and future electron-positron annihilation experiments.

Based on $(2712.4\pm 14.3)\times {10}^6\psi (3686)$ events, we investigate four hadronic decay modes of the $P$-wave charmonium spin-singlet state $h_c{(}^1{P}_1)\to h^{+}{h}^{-}{\pi }^0/\eta$ ($h=\pi$ or $K$) via the process $\psi (3686)\to {\pi }^0{h}_c$ at BESIII. The $h_c\to {\pi }^{+}{\pi }^{-}{\pi }^0$ decay is observed with a significance of $9.6\sigma$ after taking into account systematic uncertainties. Evidences for $h_c\to K^{+}{K}^{-}{\pi }^0$ and $h_c\to K^{+}{K}^{-}\eta$ are found with significances of $3.5\sigma$ and $3.3\sigma$, respectively, after considering the systematic uncertainties. The branching fractions of these decays are measured to be $\mathcal{B}(h_c\to {\pi }^{+}{\pi }^{-}{\pi }^0)=(1.36\pm 0.16\pm 0.14)\times {10}^{-3}$, $\mathcal{B}(h_c\to K^{+}{K}^{-}{\pi }^0)=(3.26\pm 0.84\pm 0.36)\times {10}^{-4}$, and $\mathcal{B}(h_c\to K^{+}{K}^{-}\eta )=(3.13\pm 1.08\pm 0.38)\times {10}^{-4}$, where the first uncertainties are statistical and the second are systematic. No significant signal of $h_c\to {\pi }^{+}{\pi }^{-}\eta$ is found, and the upper limit of its decay branching fraction is determined to be $\mathcal{B}(h_c\to {\pi }^{+}{\pi }^{-}\eta )<4.0\times {10}^{-4}$ at the 90% confidence level.