We explore the impact of choosing different sets of time-delay interferometry (TDI) variables for detecting and reconstructing stochastic gravitational wave background (SGWB) signals and estimating the instrumental noise in LISA. Most works in the literature build their data analysis pipelines relying on a particular set of TDI channels, the so-called AET variables, which are orthogonal under idealized conditions. By relaxing the assumption of a perfectly equilateral LISA configuration, we investigate to which degree these channels remain orthogonal and compare them to other TDI channels. We show that different sets of TDI variables are more robust under perturbations of the perfect equilateral configuration, better preserving their orthogonality and, thus, leading to a more accurate estimate of the instrumental noise. Moreover, we investigate the impact of considering the noise levels associated with each instrumental noise source to be independent of one another, generalizing the analysis from two to twelve noise parameters. We find that, in this scenario, the assumption of orthogonality is broken for all the TDI variables, leading to a misestimation of measurement error for some of the noise parameters. Remarkably, we find that for a flat power-law signal, the reconstruction of the signal parameters is nearly unaffected in these various configurations.

Two major challenges of contemporary cosmology are the Hubble tension and the cosmic dipole tension. At the crossroads of these, we investigate the impact of peculiar velocities on estimations of the Hubble constant from time-delay cosmography. We quantify the bias on the inference of the Hubble constant due to peculiar velocities of the lens, the source and of the observer. The former two, which may cancel from one system to another, affect the determination of the angular diameter distances in the time-delay formula, and reconstructed quantities like the angle to the source, via a lens model. On the other hand, the peculiar velocity of the observer, which is a debated quantity in the context of the cosmic dipole tension, systematically affects observed angles through aberration, redshifts, angular diameter distance and reconstructed quantities. We compute in detail the effect of these peculiar velocities on the inference of the Hubble constant to linear order in the peculiar velocities for the seven lenses of the H0LiCOW/TDCOSMO collaboration. The bias generated by the observer’s peculiar velocity alone can reach 1.15% for the lenses which are well aligned with it. This results in a 0.25% bias for the seven combined lenses. Assuming a typical peculiar velocity of $300\mathrm{km}{\mathrm{s}}^{-1}$ for the lens and the source galaxies, these add an additional random uncertainty, which can reach 1% for an individual lens, but reduces to 0.24% for the full TDCOSMO sample. The picture may change if peculiar velocities turn out to be larger than expected. Any time-delay cosmography program which aims for percent precision on the Hubble constant may need to take this source of systematic bias into account. This is especially so for future ground-based surveys which cover a fraction of the celestial sphere that is well aligned with the observer’s peculiar velocity.

We use $n_f=2+1$ Wilson-clover gauge-field ensembles from the Coordinated Lattice Simulations (CLS) Consortium in a lattice nonrelativistic QCD (NRQCD) setup to predict the binding energy of an $I(J^P)=0(1^{+})$ $ud\overline{b}\overline{b}$ tetraquark and a $\frac{1}{2}(1^{+})\ell s\overline{b}\overline{b}$ tetraquark. We determine the binding energies with respect to the relevant $B{B}^{*}$ and $B_s{B}^{*}$ thresholds, respectively, to be 112.0(13.2) MeV for the $ud\overline{b}\overline{b}$, and 46.4(12.3) MeV for the $\ell s\overline{b}\overline{b}$. We also determine the ground-state $J^P=0^{+}$ $B_{s0}^{*}$ and $1^{+}$ $B_{s1}$ mesons to lie 75.4(14.0) and 78.7(13.9) MeV below the $BK$ and $B^{*}K$ thresholds, respectively. Our errors are entirely dominated by systematics due to discretization effects. To achieve these measurements, we performed a neural network based nonperturbative tuning of the lattice NRQCD Hamiltonian’s parameters against the basic bottomonium spectrum. For all lattice spacings considered we can reproduce the continuum splittings of low-lying bottomonia. It is worth remarking that our nonperturbative tuning parameters deviate from 1 by significant amounts, particularly the term $c_2$.

Cosmic rays are the only agent able to penetrate into the interior of dense molecular clouds. Depositing (part of) their energy through ionization, cosmic rays play an essential role in determining the physical and chemical evolution of star-forming regions. To a first approximation their effect can be quantified by the cosmic-ray induced ionization rate. Interestingly, theoretical estimates of the ionization rate assuming the cosmic-ray spectra observed in the local interstellar medium result in an ionization rate that is one to two orders of magnitude below the values inferred from observations. However, due to the discrete nature of sources, the local spectra of MeV cosmic rays are in general not representative for the spectra elsewhere in the Galaxy. Such stochasticity effects have the potential of reconciling modeled ionization rates with measured ones. Here, we model the distribution of low-energy cosmic-ray spectra expected from a statistical population of supernova remnants in the Milky Way. The corresponding distribution for the ionization rate is derived and confronted with data. We find that the stochastic uncertainty helps with explaining the surprisingly high ionization rates observed in many molecular clouds.

We present lattice-QCD calculations of the hadronic form factors for the semileptonic decays $D\to \pi \ell \nu$, $D\to K\ell \nu$, and $D_s\to K\ell \nu$. Our calculation uses the highly improved staggered quark (HISQ) action for all valence and sea quarks and includes $N_f=2+1+1$ MILC ensembles with lattice spacings ranging from $a\approx 0.12\mathrm{fm}$ down to 0.042 fm. At most lattice spacings, an ensemble with physical-mass light quarks is included. The HISQ action allows all the quarks to be treated with the same relativistic light-quark action, allowing for nonperturbative renormalization using partial conservation of the vector current. We combine our results with experimental measurements of the differential decay rates to determine ${|V_{cd}|}^{D\to \pi }=0.2238(11{)}^{\text{Expt}}(15{)}^{\mathrm{QCD}}(04{)}^{\mathrm{EW}}(02{)}^{\mathrm{SIB}}[22{]}^{\mathrm{QED}}$ and ${|V_{cs}|}^{D\to K}=0.9589(23{)}^{\text{Expt}}(40{)}^{\mathrm{QCD}}(15{)}^{\mathrm{EW}}(05{)}^{\mathrm{SIB}}[95{]}^{\mathrm{QED}}$. This result for $|V_{cd}|$ is the most precise to date, with a lattice-QCD error that is, for the first time for the semileptonic extraction, at the same level as the experimental error. Using recent measurements from BES III, we also give the first-ever determination of ${|V_{cd}|}^{D_s\to K}=0.258(15{)}^{\text{Expt}}(01{)}^{\mathrm{QCD}}[03{]}^{\mathrm{QED}}$ from $D_s\to Kl\nu$. Our results also furnish new Standard Model calculations of the lepton flavor universality ratios $R_{\mu /e}^{D\to \pi }=0.98671(17{)}^{\mathrm{QCD}}[500{]}^{\mathrm{QED}}$, $R_{\mu /e}^{D\to K}=0.97606(16{)}^{\mathrm{QCD}}[500{]}^{\mathrm{QED}}$, and $R_{\mu /e}^{D_s\to K}=0.98099(10{)}^{\mathrm{QCD}}[500{]}^{\mathrm{QED}}$, which are consistent within $2\sigma$ with experimental measurements. Our extractions of $|V_{cd}|$ and $|V_{cs}|$, when combined with a value for $|V_{cb}|$, provide the most precise test of second-row Cabibbo-Kobayashi-Maskawa unitarity, finding agreement with unitarity at the level of one standard deviation.

In many models, the sources of ultrahigh-energy cosmic rays (UHECRs) are assumed to accelerate particles to the same maximum energy. Motivated by the fact that candidate astrophysical accelerators exhibit a vast diversity in terms of their relevant properties such as luminosity, Lorentz factor, and magnetic field strength, we study the compatibility of a population of sources with nonidentical maximum cosmic-ray energies with the observed energy spectrum and composition of UHECRs at Earth. For this purpose, we compute the UHECR spectrum emerging from a population of sources with a power-law, or broken-power-law, distribution of maximum energies, applicable to a broad range of astrophysical scenarios. We find that the allowed source-to-source variance of the maximum energy must be small to describe the data if a power-law distribution is considered. Even in the most extreme scenario, with a very sharp cutoff of individual source spectra and negative redshift evolution of the accelerators, the maximum energies of 90% of sources must be identical within a factor of 3—in contrast to the variance expected for astrophysical sources. Substantial variance of the maximum energy in the source population is only possible if the maximum energies follow a broken-power-law distribution with a very steep spectrum above the break. However, in this scenario, the individual source energy spectra are required to be unusually hard with increasing energy output as a function of energy.

Large-field inflation is a major class of inflation models featuring a near- or super-Planckian excursion of the inflaton field. We point out that the large excursion generically introduces significant scale dependence to spectator fields through inflaton couplings, which in turn induces characteristic distortions to the oscillatory shape dependence in the primordial bispectrum mediated by a spectator field. This so-called cosmological collider signal can thus be a useful indicator of large field excursions. We show an explicit example with signals from the “tower states” motivated by the swampland distance conjecture.

We explore the impact of small-scale flavor conversions of neutrinos, the so-called fast flavor conversions (FFCs), on the dynamical evolution and neutrino emission of core-collapse supernovae (CCSNe). In order to do that, we implement FFCs in the spherically symmetric (1D) CCSN simulations of a $20M_{\odot }$ progenitor model parametrically, assuming that FFCs happen at densities lower than a systematically varied threshold value and lead to an immediate flavor equilibrium consistent with lepton number conservation. We find that besides hardening the ${\nu }_e$ and ${\overline{\nu }}_e$ spectra, which helps the expansion of the shock by enhanced postshock heating, FFCs can cause significant, nontrivial modifications of the energy transport in the SN environment via increasing the ${\nu }_{\mu ,\tau }$ luminosities. In our nonexploding models this results in extra cooling of the layers around the neutrinospheres, which triggers a faster contraction of the protoneutron star and hence, in our 1D models, hampers the CCSN explosion. Although our study is limited by the 1D nature of our simulations, it provides valuable insights into how neutrino flavor conversions in the deepest CCSN regions can impact the neutrino release and the corresponding response of the stellar medium.

New feebly interacting particles would emerge from a supernova core with 100-MeV-range energies and produce $\gamma$ rays by subsequent decays. These would contribute to the diffuse cosmic $\gamma$-ray background or would have shown up in the Solar Maximum Mission satellite from SN 1987A. However, we show for the example of axionlike particles that, even at distances beyond the progenitor star, the decay photons may not escape and can instead form a fireball, a plasma shell with $T\lesssim 1\mathrm{MeV}$. Thus, existing arguments do not exclude axionlike particles with few 10 MeV masses and a two-photon coupling of a few ${10}^{-10}{\mathrm{GeV}}^{-1}$. However, the energy would have showed up in sub-MeV photons, which were not seen from SN 1987A in the Pioneer Venus Orbiter, closing again this new window. A careful reassessment is required for other particles that were constrained in similar ways.

There exist 4D $\mathcal{N}=2$ superconformal field theories (SCFTs) in class $\mathcal{S}$ that have different constructions as punctured Riemann surfaces, but which nevertheless appear to describe the same physics. Some of these class $\mathcal{S}$ theories have an alternative construction as torus-compactifications of 6D (1, 0) SCFTs. We demonstrate that the 6D SCFTs are isomorphic. Each 6D SCFT in question can be obtained from a parent 6D SCFT by Higgs branch renormalization group flow, and the parent theory possesses a discrete symmetry under which the relevant Higgs branch flows are exchanged. The existence of this discrete symmetry, which may be embedded in an enhanced continuous symmetry, proves that the original pair of class $\mathcal{S}$ theories are, in fact, isomorphic.

The swampland cobordism conjecture successfully predicts the supersymmetric spectrum of 7-branes of IIB/F-theory. Including reflections on the F-theory torus, it also predicts the existence of new nonsupersymmetric objects, which we dub reflection 7-branes (R7-branes). We present evidence that these R7-branes only exist at strong coupling. R7-branes serve as end of the world branes for 9D theories obtained from type IIB asymmetric orbifold and Dabholkar-Park orientifold backgrounds, and an anomaly inflow analysis suggests the existence of a gapless Weyl fermion, which would have the quantum numbers of a goldstino. Using general arguments, we conclude that different kinds of branes are able to end on the R7, and accounting for their charge requires exotic localized degrees of freedom, for which the simplest possibility is a massless 3-form field on the R7-brane worldvolume. We also show how to generalize the standard F-theory formalism to account for reflections.

We study photon geodesics in topological solitons that have the same asymptotic properties as Schwarzschild black holes. These are coherent states in string theory corresponding to pure deformations of spacetime through the dynamics of compact extra dimensions. We compare these solutions with Schwarzschild black holes by computing null geodesics, deriving Lyapunov exponents, and imaging their geometries as seen by a distant observer. We show that topological solitons are remarkably similar to black holes in apparent size and scattering properties, while being smooth and horizonless. Incoming photons experience very high redshift, inducing phenomenological horizonlike behaviors from the point of view of photon scattering. Thus, they provide a compelling case for real-world gravitational solitons and topological alternatives to black holes from string theory.

Clusters of galaxies are the largest gravitationally bound systems in the Universe. Their dynamics are dominated by dark matter (DM), which makes them among the best targets for indirect DM searches. We analyze 12 years of data collected by the Fermi Large Area Telescope (Fermi-LAT) in the direction of 49 clusters of galaxies selected for their proximity to the Earth and their high x-ray flux, which makes them the most promising targets. We first create physically motivated models for the DM density around each cluster considering different assumptions for the substructure distribution. Then we perform a combined search for a $\gamma$-ray signal in the Fermi-LAT data between 500 MeV and 1 TeV. We find a signal of $\gamma$ rays potentially associated with DM that is at a statistical significance of $2.5\sigma -3.0\sigma$ when considering a slope for the subhalo mass distribution $\alpha =1.9$ and minimum mass of $M_{\min }={10}^{-6}{M}_{\odot }$. The best-fit DM mass and annihilation cross sections for a $b\overline{b}$ annihilation channel are $m_{\chi }=40–60\mathrm{GeV}$ and $⟨\sigma v⟩=(2–4)\times {10}^{-25}{\mathrm{cm}}^3/\mathrm{s}$. When we consider $\alpha =2.0$ and $M_{\min }={10}^{-9}{M}_{\odot }$, the best fit of the cross section reduces to $⟨\sigma v⟩=(4–10)\times {10}^{-26}{\mathrm{cm}}^3/\mathrm{s}$. For both DM substructure models there is a tension between the values of $⟨\sigma v⟩$ that we find and the upper limits obtained with the nondetection of a $\gamma$-ray flux from Milky Way dwarf spheroidal galaxies. This signal is thus more likely associated with $\gamma$ rays produced in the intracluster region by cosmic rays colliding with gas and photon fields.

Using lattice simulations we calculate the rate of baryon number violating processes, the sphaleron rate, in the Standard Model with an external (hyper)magnetic field for temperatures across the electroweak crossover, focusing on the broken phase. Additionally, we compute the Higgs expectation value and the pseudocritical temperature. The electroweak crossover shifts to lower temperatures with an increasing external magnetic field, bringing the onset of the suppression of the baryon number violation with it. When the hypermagnetic field reaches the magitude $B_Y\approx 2T^2$ the crossover temperature is reduced from 160 to 145 GeV. In the broken phase for small magnetic fields the rate behaves quadratically as a function of the magnetic flux. For stronger magnetic fields the rate reaches a linear regime which lasts until the field gets strong enough to restore the electroweak symmetry where the symmetric phase rate is reached.

We perform a novel multimessenger analysis for the identification and parameter estimation of the standing accretion shock instability (SASI) in a core-collapse supernova with neutrino and gravitational-wave (GW) signals. In the neutrino channel, this method performs a likelihood ratio test for the presence of SASI in the frequency domain. For gravitational-wave signals we process an event with a modified constrained likelihood method. Using simulated supernova signals, the properties of the Hyper-Kamiokande neutrino detector, and O3 LIGO interferometric data, we produce the two-dimensional probability density function (PDF) of the SASI activity indicator and calculate the probability of detection $P_{\mathrm{D}}$ as well as the false identification probability $P_{\mathrm{FI}}$. We discuss the probability to establish the presence of the SASI as a function of the source distance in each observational channel, as well as jointly. Compared to a single-messenger approach, the joint analysis results in a $P_{\mathrm{D}}$ (at $P_{\mathrm{FI}}=0.1$) of SASI activities that is larger by up to $\approx 40\%$ for a distance to the supernova of 5 kpc. We also discuss how accurately the frequency and duration of the SASI activity can be estimated in each channel separately. Our methodology is suitable for implementation in a realistic data analysis and a multimessenger setting.

We constrain six possible extensions to the $\mathrm{\Lambda }$ cold dark matter (CDM) model using measurements from the Dark Energy Survey’s first three years of observations, alone and in combination with external cosmological probes. The DES data are the two-point correlation functions of weak gravitational lensing, galaxy clustering, and their cross-correlation. We use simulated data vectors and blind analyses of real data to validate the robustness of our results to astrophysical and modeling systematic errors. In many cases, constraining power is limited by the absence of theoretical predictions beyond the linear regime that are reliable at our required precision. The $\mathrm{\Lambda }\mathrm{CDM}$ extensions are dark energy with a time-dependent equation of state, nonzero spatial curvature, additional relativistic degrees of freedom, sterile neutrinos with eV-scale mass, modifications of gravitational physics, and a binned ${\sigma }_8(z)$ model which serves as a phenomenological probe of structure growth. For the time-varying dark energy equation of state evaluated at the pivot redshift we find $(w_{\mathrm{p}},w_a)=(-0.99_{-0.17}^{+0.28},-0.9\pm 1.2)$ at 68% confidence with $z_{\mathrm{p}}=0.24$ from the DES measurements alone, and $(w_{\mathrm{p}},w_a)=(-1.03_{-0.03}^{+0.04},-0.4_{-0.3}^{+0.4})$ with $z_{\mathrm{p}}=0.21$ for the combination of all data considered. Curvature constraints of ${\mathrm{\Omega }}_k=0.0009\pm 0.0017$ and effective relativistic species $N_{\mathrm{eff}}=3.10_{-0.16}^{+0.15}$ are dominated by external data, though adding DES information to external low-redshift probes tightens the ${\mathrm{\Omega }}_k$ constraints that can be made without cosmic microwave background observables by 20%. For massive sterile neutrinos, DES combined with external data improves the upper bound on the mass $m_{\mathrm{eff}}$ by a factor of 3 compared to previous analyses, giving 95% limits of $(\mathrm{\Delta }{N}_{\mathrm{eff}},m_{\mathrm{eff}})\le (0.28,0.20\mathrm{eV})$ when using priors matching a comparable Planck analysis. For modified gravity, we constrain changes to the lensing and Poisson equations controlled by functions $\mathrm{\Sigma }(k,z)={\mathrm{\Sigma }}_0{\mathrm{\Omega }}_{\mathrm{\Lambda }}(z)/{\mathrm{\Omega }}_{\mathrm{\Lambda },0}$ and $\mu (k,z)={\mu }_0{\mathrm{\Omega }}_{\mathrm{\Lambda }}(z)/{\mathrm{\Omega }}_{\mathrm{\Lambda },0}$, respectively, to ${\mathrm{\Sigma }}_0=0.6_{-0.5}^{+0.4}$ from DES alone and $({\mathrm{\Sigma }}_0,{\mu }_0)=(0.04\pm 0.05,0.08_{-0.19}^{+0.21})$ for the combination of all data, both at 68% confidence. Overall, we find no significant evidence for physics beyond $\mathrm{\Lambda }\mathrm{CDM}$.

We test the hypothesis of starburst galaxies as sources of ultrahigh energy cosmic rays and high energy neutrinos. The computation of interactions of ultrahigh energy cosmic rays in the starburst environment as well as in the propagation to Earth is made using a modified version of the Monte Carlo code SimProp, where hadronic processes in the environment of sources are implemented for the first time. Taking into account a star-formation-rate distribution of sources, the fluxes of ultrahigh energy cosmic rays and high energy neutrinos are computed and compared with observations, and the explored parameter space for the source characteristics is discussed. We find that, depending on the density of the gas in the source environment, spallation reactions could exceed the outcome in neutrinos from photohadronic interactions in the source environment and in the extragalactic space.

Motivated by properties of tensor networks, we conjecture that an arbitrary gravitating region $a$ can be assigned a generalized entanglement wedge $E\supset a$, such that quasilocal operators in $E$ have a holographic representation in the full algebra generated by quasilocal operators in $a$. The Universe need not be asymptotically flat or anti–de Sitter (AdS), and $a$ need not be asymptotic or weakly gravitating. On a static Cauchy surface $\mathrm{\Sigma }$, we propose that $E$ is the superset of $a$ that minimizes the generalized entropy. We prove that $E$ satisfies a no-cloning theorem and appropriate forms of strong subadditivity and nesting. If $a$ lies near a portion $A$ of the conformal boundary of AdS space, our proposal reduces to the quantum minimal surface prescription applied to $A$. We also discuss possible covariant extensions of this proposal, although none prove completely satisfactory. Our results are consistent with the conjecture that information in $E$ that is spacelike to $a$ in the semiclassical description can nevertheless be recovered from $a$, by microscopic operators that break that description. We thus propose that $E$ quantifies the range of holographic encoding, an important nonlocal feature of quantum gravity, in general spacetimes.

We present nonlinear solutions of Vlasov perturbation theory (VPT), describing gravitational clustering of collisionless dark matter with dispersion and higher cumulants induced by orbit crossing. We show that VPT can be cast into a form that is formally analogous to standard perturbation theory (SPT), but including additional perturbation variables, nonlinear interactions, and a more complex propagation. VPT nonlinear kernels have a crucial decoupling property: for fixed total momentum, the kernels become strongly suppressed when any of the individual momenta cross the dispersion scale into the nonlinear regime. This screening of UV modes allows us to compute nonlinear corrections to power spectra even for cosmologies with very blue power-law input spectra, for which SPT diverges. We compare predictions for the density and velocity divergence power spectra as well as the bispectrum at one-loop order to $N$-body results in a scaling universe with spectral indices $-1\le n_s\le +2$. We find a good agreement up to the nonlinear scale for all cases, with a reach that increases with the spectral index $n_s$. We discuss the generation of vorticity as well as vector and tensor modes of the velocity dispersion, showing that neglecting vorticity when including dispersion would lead to a violation of momentum conservation. We verify momentum conservation when including vorticity, and compute the vorticity power spectrum at two-loop order, necessary to recover the correct large-scale limit with slope $n_w=2$. Comparing to our $N$-body measurements confirms the cross-over from $k^4$ to $k^2$ scaling at large scales. Our results provide a proof-of-principle that perturbative techniques for dark matter clustering can be systematically improved based on the known underlying collisionless dynamics.

The standard perturbation theory (SPT) approach to gravitational clustering is based on a fluid approximation of the underlying Vlasov-Poisson dynamics, taking only the zeroth and first cumulant of the phase-space distribution function into account (density and velocity fields). This assumption breaks down when dark matter particle orbits cross and leads to well-known problems, e.g., an anomalously large backreaction of small-scale modes onto larger scales that compromises predictivity. We extend SPT by incorporating second and higher cumulants generated by orbit crossing. For collisionless matter, their equations of motion are completely fixed by the Vlasov-Poisson system, and thus we refer to this approach as Vlasov Perturbation Theory (VPT). Even cumulants develop a background value, and they enter the hierarchy of coupled equations for the fluctuations. The background values are in turn sourced by power spectra of the fluctuations. The latter can be brought into a form that is formally analogous to SPT, but with an extended set of variables and linear as well as nonlinear terms, that we derive explicitly. In this paper, we focus on linear solutions, which are far richer than in SPT, showing that modes that cross the dispersion scale set by the second cumulant are highly suppressed. We derive stability conditions on the background values of even cumulants from the requirement that exponential instabilities be absent. We also compute the expected magnitude of averaged higher cumulants for various halo models and show that they satisfy the stability conditions. Finally, we derive self-consistent solutions of perturbations and background values for a scaling universe and study the convergence of the cumulant expansion. The VPT framework provides a conceptually straightforward and deterministic extension of SPT that accounts for the decoupling of small-scale modes.