Creating accurate and low-noise covariance matrices represents a formidable challenge in modern-day cosmology. We present a formalism to compress arbitrary observables into a small number of bins by projection into a model-specific subspace that minimizes the prior-averaged log-likelihood error. The lower dimensionality leads to a dramatic reduction in covariance matrix noise, significantly reducing the number of mocks that need to be computed. Given a theory model, a set of priors, and a simple model of the covariance, our method works by using singular value decompositions to construct a basis for the observable that is close to Euclidean; by restricting to the first few basis vectors, we can capture almost all the constraining power in a lower-dimensional subspace. Unlike conventional approaches, the method can be tailored for specific analyses and captures nonlinearities that are not present in the Fisher matrix, ensuring that the full likelihood can be reproduced. The procedure is validated with full-shape analyses of power spectra from Baryon Oscillation Spectroscopic Survey (BOSS) DR12 mock catalogs, showing that the 96-bin power spectra can be replaced by 12 subspace coefficients without biasing the output cosmology; this allows for accurate parameter inference using only $\sim 100$ mocks. Such decompositions facilitate accurate testing of power spectrum covariances; for the largest BOSS data chunk, we find the following: (a) analytic covariances provide accurate models (with or without trispectrum terms); and (b) using the sample covariance from the MultiDark-Patchy mocks incurs a $\sim 0.5\sigma$ shift in ${\mathrm{\Omega }}_m$, unless the subspace projection is applied. The method is easily extended to higher order statistics; the $\sim 2000$-bin bispectrum can be compressed into only $\sim 10$ coefficients, allowing for accurate analyses using few mocks and without having to increase the bin sizes.

In a simplified model including a singlet vectorlike top partner $T$ with charge $2/3$, we investigate the single production of $T$ decaying into $Wb$ in the four flavor scheme at the 14 TeV LHC, high luminosity LHC, and future high energy $pp$ colliders, such as high energy (HE)-LHC with $\sqrt{s}=27\mathrm{TeV}$ and FCC-hh with $\sqrt{s}=100\mathrm{TeV}$. By performing a detailed detector simulation and the background analysis, we display the excluding capability on the top partner $T$ at different colliders with a different integrated luminosity at 95% confidence level. We find that the excluding capability is enhanced obviously with the increase of the collision energy and the HE-LHC and FCC-hh have a greater advantage in high $m_T$ regions. If the colliders reach their high integrated luminosity, (1) the high luminosity LHC can exclude the region $g^{*}\in [0.19,0.50]$ with $m_T\in [1300\mathrm{GeV},2420\mathrm{GeV}]$ with $3{\mathrm{ab}}^{-1}$, (2) the HE-LHC can exclude the regions $g^{*}\in [0.07,0.50]$ with $m_T\in [1300\mathrm{GeV},4500\mathrm{GeV}]$ with $15{\mathrm{ab}}^{-1}$, and (3)the FCC-hh can exclude the regions $g^{*}\in [0.02,0.50]$ with $m_T\in [1300\mathrm{GeV},11250\mathrm{GeV}]$ with $30{\mathrm{ab}}^{-1}$. For these typical integrated luminosities, we also display the discovering capability on the top partner $T$ at different colliders. Besides, if the narrow width approximation limit is considered, we find that the excluding and discovering parameter space will be reduced.

We investigate the leading-twist transverse-momentum-dependent distribution functions (TMDs) for a physical electron, a spin-$1/2$ composite system consisting of a bare electron and a photon, using the basis light-front quantization (BLFQ) framework. The light-front wave functions of the physical electron are obtained from the eigenvectors of the light-front QED Hamiltonian. We evaluate the TMDs using the overlaps of the light-front wave functions. The BLFQ results are found to be in excellent agreement with those TMDs calculated using lowest-order perturbation theory.

There is a newly emerging tension between determinations of $V_{us}$ from different sources (known as the Cabibbo anomaly), clearly demonstrated by the new $R(V_{us})$ observable which is highly sensitive to lepton flavor universality violating effects. We explore this observable from the perspective of the Standard Model Effective Field Theory and show there is a discrepancy between $R(V_{us})$ and existing electroweak precision observables (EWPO) in a simple single operator dominated scenario. We explore all possible single particle extensions of the Standard Model that can generate the Cabibbo anomaly effect and show how they cannot simply reconcile the current data. We further examine the future of EWPO at the ILC or FCC-ee experiments and discuss the effect on the tension of a change in specific EW observables.

We discuss an enhancement of the Brown-Henneaux boundary conditions in three-dimensional AdS general relativity to encompass Weyl transformations of the boundary metric. The resulting asymptotic symmetry algebra, after a field-dependent redefinition of the generators, is a direct sum of two copies of the Witt algebra and the Weyl Abelian sector. The charges associated with Weyl transformations are nonvanishing, integrable but not conserved due to a flux driven by the Weyl anomaly coefficient. The charge algebra admits an additional nontrivial central extension in the Weyl sector, related to the well-known Weyl anomaly. We then construct the holographic Weyl current and show that it satisfies an anomalous Ward-Takahashi identity of the boundary theory.

We investigate exotic supergravity theories in 6D with maximal (4,0) and (3,1) supersymmetry, which were conjectured by Hull to exist and to describe strong coupling limits of $\mathcal{N}=8$ theories in 5D. These theories involve exotic gauge fields with nonstandard Young tableaux representations, subject to (self-)duality constraints. We give novel actions in a $5+1$ split of coordinates whose field equations reproduce those of the free bosonic (4,0) and (3,1) theory, respectively, including the (self-)duality relations. Evidence is presented for a master exceptional field theory formulation with an extended section constraint that, depending on the solution, produces the (4,0), (3,1) or the conventional (2,2) theory. We comment on the possible construction of a fully nonlinear master exceptional field theory.

We find that scattering amplitudes in massive scalar QCD can manifest the duality between color and kinematics at loop-level. Specifically we construct the one-loop integrands for four-point scattering between two distinct massive scalars, and the five-point process encoding the first correction to massive scalar scattering with gluonic radiation. We find that factorization and the color-kinematics duality are sufficient principles to entirely bootstrap these calculations, allowing us to construct all contributions ultimately from the three-point tree-level amplitudes which are themselves entirely constrained by symmetry. Double-copy construction immediately provides the associated predictions for massive scalars scattering in the so called $\mathcal{N}=0$ supergravity theory.

Boosted and rotated tetrad backgrounds for the Minkowski space are studied in $f(\mathbb{T})$ gravity. We perform Lorentzian perturbations at first order around nontrivial backgrounds and show that some Lorentz modes can exhibit nontrivial dynamics and can propagate in time. This remarkable feature gives evidence of additional mode(s) in the Lorentzian sector which have no precedent in Lorentz-violating modified gravities; however, they can cast doubts onto even theoretical viability of these models.

We study motions of photons in an unmagnetized cold homogeneous plasma medium in the five-dimensional charged static squashed Kaluza-Klein black hole spacetime. In this case, a photon behaves as a massive particle in a four-dimensional spherically symmetric spacetime. We consider the light deflection by the squashed Kaluza-Klein black hole surrounded by the plasma in a weak-field limit. We derive corrections of the deflection angle to general relativity, which are related to the size of the extra dimension, the charge of the black hole and the ratio between the plasma and the photon frequencies.

Using the third quantization formalism we study the quantum entanglement of universes created in pairs within the framework of standard homogeneous and isotropic cosmology. In particular, we investigate entanglement quantities (entropy, temperature) around the maxima, minima and inflection points of the classical evolution. The novelty from previous works is that we show how the entanglement changes in an extended minisuperspace parametrized by the scale factor and additionally, by the massless scalar field. We study the entanglement quantities for the universes which classically exhibit big bang and other than big bang (exotic) singularities such as big brake, big freeze, big separation, and little rip. While taking into account the scalar field, we find that the entanglement entropy is finite at the big bang singularity and diverges at the maxima or minima of expansion. As for the exotic singularity models we find that the entanglement entropy or the temperature in all the critical points and singularities is either finite or infinite, but it never vanishes. This shows that each of the universes of a pair is entangled to a degree parametrized by the entanglement quantities which measure the quantumness of the system. Apart from the von Neumann entanglement entropy, we also check the behavior of the Tsallis and the Renyi entanglement entropies, and find that they behave similarly to the meters of the quantumness. Finally, we find that the best-fit relation between the entanglement entropy and the Hubble parameter (which classically marks special points of universe evolution) is of the logarithmic shape, and not polynomial, as one could initially expect.

The main aim of this paper is to analyze minimally coupled scalar fields—quintessence and phantom—as the main candidates to explain the accelerated expansion of the Universe and compare its observables to current cosmological observations; as a byproduct we present its python module. This work includes a parameter $\epsilon$ which allows to incorporate both quintessence and phantom fields within the same analysis. Examples of the potentials, so far included, are $V(\varphi )=V_0{\varphi }^{\mu }{e}^{\beta {\varphi }^{\alpha }}$ and $V(\varphi )=V_0(\cosh (\alpha \varphi )+\beta )$ with $\alpha$, $\mu$, and $\beta$ being free parameters, but the analysis can be easily extended to any other scalar field potential. Additional to the field component and the standard content of matter, the study also incorporates the contribution from spatial curvature (${\mathrm{\Omega }}_k$), as it has been the focus in recent studies. The analysis contains the most up-to-date data sets along with a nested sampler to produce posterior distributions along with the Bayesian evidence, that allows to perform a model selection. In this work, we constrain the parameter space describing the two generic potentials, and among several combinations, we found that the best fit to current data sets is given by a model slightly favoring the quintessence field with potential $V(\varphi )=V_0{\varphi }^{\mu }{e}^{\beta \varphi }$ with $\beta =0.22\pm 1.56$, $\mu =-0.41\pm 1.90$, and slightly negative curvature ${\mathrm{\Omega }}_{k,0}=-0.0016\pm 0.0018$, which presents deviations of $1.6\sigma$ from the standard lambda cold dark matter ($\mathrm{\Lambda }\mathrm{CDM}$) model. Even though this potential contains three extra parameters, the Bayesian evidence ${\mathcal{B}}_{\mathrm{\Lambda },\varphi }=2.0$ is unable to distinguish this model compared to the $\mathrm{\Lambda }\mathrm{CDM}$ with curvature (${\mathrm{\Omega }}_{k,0}=0.0013\pm 0.0018$). The potential that provides the minimal Bayesian evidence corresponds to $V(\varphi )=V_0\cosh (\alpha \varphi )$ with $\alpha =-0.61\pm 1.36$.

We consider the framework of quintessential inflation in the warm background which is caused by the dissipation of the scalar field energy density into relativistic degrees of freedom. The dissipation process has important consequences for the evolution both at the levels of background as well as perturbation and allows us to easily satisfy the observational constraints. Our numerical analysis confirms that the model conforms to observational constraints even if the field-radiation coupling strength is weak. In the warm background, we investigate the postinflationary evolution of relic gravity waves produced during inflation whose amplitude is constrained by the big bang nucleosynthesis constraint. Further, we investigate the effect of coupling on the amplitude of gravity waves and obtain the allowed phase space between the model parameters. The mechanism of quintessential inflation gives rise to blue spectrum of gravitational wave background at high frequencies. We discuss the perspectives of detection of the signal of relic gravity waves by future proposed missions. Improvements of their sensitivities in the high frequency regime, in future, might allow us to probe the blue tilt of the spectrum caused by the presence of kinetic regime in the underlying framework of inflation.

Gravitational wave memory is an important prediction of general relativity. The detection of the gravitational wave memory can be used to test general relativity and deduce the property of the gravitational wave source. A quantitative model is important for such detection and signal interpretation. Previous works on gravitational wave memory have always used the energy flux of the gravitational wave to calculate the memory. Accurately calculating the memory is highly demanded. Here we apply the Bondi-Metzner-Sachs method to calculate the gravitational wave memory. Our method does not need slow motion and weak field conditions for the gravitational wave source. This method can accurately calculate the memory if the nonmemory waveform is known. As an example, we combine our method with the matured numerical relativity result of a nonmemory waveform for binary black hole coalescence. We calculate the waveform for the memory which can be used to aid memory detection and help us understand the gravitational wave source. Our calculation result is consistent with the numerical relativity result of memory. We determine the dependence of the memory amplitude on the mass ratio and the spins of the two spin-aligned black holes.

To approximately compute the nonrelativistic ground state of an electrically nonneutral star, an exactly solvable model was recently introduced, and partly solved, in Krivoruchenko et al. [Phys. Rev. D 97, 083016 (2018)]. The model generalizes the well-known Lane-Emden equation of a polytropic gas ball of index $n=1$ to a two-fluid setting. Here its complete solution is presented in terms of simple elementary functions; it is also generalized to a more-than-two-fluid setting where it remains exactly solvable. It is shown that, given the number of nuclei, a maximal negatively charged solution and a maximal positively charged solution exist, plus a continuous family of solutions which interpolates between these extremes. Numerical comparisons show that this exactly solvable model captures the qualitative behavior of the more physical model it is supposed to approximate. Furthermore, it correctly answers the question: how nonneutral can the star be? The answer is independent of the speed of light $c$ and the Planck quantum $h$. It supports Penrose’s weak cosmic censorship hypothesis, in the sense that the bounds on the excess charge are compatible with the bound on the charge of a Reissner-Weyl-Nordström black hole.

Schwinger pair production is analyzed in a Belavin, Polyakov, Schwarz and Tyupkin (BPST) instanton background and in its $\mathrm{SL}(2,\mathbb{C})$ complex extension for complex scalar particles. A non-Abelian extension of the worldline instanton method is utilized, wherein Wong’s equations in a coherent state picture adopted for $\mathrm{SL}(2,\mathbb{C})$ are solved in Euclidean spacetime. While pair production is not predicted in the BPST instanton, a complex extension of the BPST instanton, existing as parallel fields in Minkowski spacetime, is shown to decay via the Schwinger effect.

The consecutive steps of cascade decay initiated by $H\to \tau \tau$ can be useful for the measurement of Higgs couplings and in particular of the Higgs boson parity. In the previous papers we have found that multidimensional signatures of the ${\tau }^{\pm }\to {\pi }^{\pm }{\pi }^0\nu$ and ${\tau }^{\pm }\to 3{\pi }^{\pm }\nu$ decays can be used to distinguish between scalar and pseudoscalar Higgs state. The machine learning techniques (ML) of binary classification, offered break-through opportunities to manage such complex multidimensional signatures. The classification between two possible $CP$ states: scalar and pseudoscalar, is now extended to the measurement of the hypothetical mixing angle of Higgs boson parity states. The functional dependence of $H\to \tau \tau$ matrix element on the mixing angle is predicted by theory. The potential to determine preferred mixing angle of the Higgs boson events sample including $\tau$-decays is studied using deep neural network. The problem is addressed as classification or regression with the aim to determine the per-event: (a) probability distribution (spin weight) of the mixing angle; (b) parameters of the functional form of the spin weight; (c) the most preferred mixing angle. Performance of proposed methods is evaluated and compared.

We study the time evolution of the chirality imbalance $n_5$ and the chiral magnetic effect (CME) under the external parallel electromagnetic (EM) fields without assuming the artificial chiral asymmetric source. We adopt the time-dependent Sauter-type electric and constant magnetic field, and obtain analytical solutions of the Dirac equation for a massive fermion. We use the point-split regularization to calculate the vacuum contribution in the gauge invariant way. As a result, we find that $n_5$ and CME current increase substantially as the electric field increases, and stay finite after the electric field is switched off. The chirality imbalance and CME current are shown to consist of a dominant contribution, which is essentially proportional to relativistic velocity, and a small oscillating part. We find a simple analytical relation between $n_5$ and the fermion pair-production rate from the vacuum. We also discuss the dynamical origin of the chirality imbalance in detail.

We explore the 1-loop renormalization group flow of two models coming from a generalization of the Connes-Lott version of noncommutative geometry in Lorentzian signature: the noncommutative Standard Model and its $B-L$ extension. Both make predictions on coupling constants at high energy, but only the latter is found to be compatible with the top quark and Higgs boson masses at the electroweak scale. We took into account corrections introduced by threshold effects and the relative positions of the Dirac and Majorana neutrino mass matrices and found them to be important. Some effects of 2-loop corrections are briefly discussed. The model is consistent with experiments only for a very small part of its parameter space and is thus predictive. The masses of the $Z^{\prime }$ and $B-L$ breaking scalar are found to be of the order ${10}^{14}\mathrm{GeV}$.

We investigate the prospect of detecting the dark matter (DM) candidate in the three-loop radiative neutrino mass generation model extended with large electroweak multiplets of the Standard Model (SM) gauge group, at the future imaging atmospheric Cherenkov telescope known as the Cherenkov Telescope Array (CTA). We find that the addition of such large electroweak multiplets leads to a sizable Sommerfeld enhanced annihilation of the DM with an $O(\mathrm{TeV})$ mass, into the SM gauge bosons, which results in continuum- and line-like spectra of very high-energy (VHE) gamma rays, and therefore becomes observable for the CTA. We determine the viable models by setting the upper limit on the $SU(2{)}_L$ isospin of the multiplets from the partial-wave unitarity constraints and the appearance of a low-scale Landau pole in the gauge coupling. Afterwards, by considering the continuum VHE gamma rays produced from the DM annihilation at the Galactic Center, we probe the parameter space of the model using the sensitivity reach of the CTA.

Extraction of hadronic observables at finite momenta from lattice QCD (LQCD) is constrained by the well-known signal-to-noise problems afflicting all such LQCD calculations. Traditional quark smearing algorithms are commonly used tools to improve the statistical quality of hadronic $n$-point functions, provided operator momenta are small. The momentum smearing algorithm of Bali et al. extends the range of momenta that are cleanly accessible and has facilitated countless novel lattice calculations. Momentum smearing has, however, not been explicitly demonstrated within the framework of distillation. In this work we extend the momentum-smearing idea by exploring a few modifications to the distillation framework. Together with enhanced time slice sampling and expanded operator bases engendered by distillation, we find ground-state nucleon energies can be extracted reliably for $|\overrightarrow{p}|\lesssim 3\mathrm{GeV}$ and matrix elements featuring a large momentum dependence can be resolved.