ShantanuT01/DACTYL-Pretraining huggingface dataset:
The standard relation between the cosmological redshift and cosmic scale factor underlies cosmological inference from virtually all kinds of cosmological observations, leading to the emergence of the LambdaCDM cosmological model. This relation is not a fundamental theory and thus observational determination of this function (redshift remapping) should be regarded as an insightful alternative to holding its standard form in analyses of cosmological data. Here we present non-parametric reconstructions of redshift remapping in dark-matter-dominated models and constraints on cosmological parameters from a joint analysis of all primary cosmological probes including the local measurement of the Hubble constant, Type Ia supernovae, baryonic acoustic oscillations (BAO), Planck observations of the cosmic microwave background (CMB) radiation (temperature power spectrum) and cosmic chronometers. The reconstructed redshift remapping points to an additional boost of redshift operating in late epoch of cosmic evolution, but affecting both low-redshift observations and the CMB. The model predicts a significant difference between the actual Hubble constant, h=0.48+/-0.02, and its local determination, h_obs=0.73+/-0.02. The ratio of these two values coincides closely with the maximum expansion rate inside voids formed in the corresponding open cosmological model with Omega_m=0.87+/-0.03, whereas the actual value of the Hubble constant implies the age of the Universe that is compatible with the Planck LambdaCDM cosmology. The new dark-matter-dominated model with redshift remapping provides excellent fits to all data and eliminates recently reported tensions between the Planck LambdaCDM cosmology, the local determination of the Hubble constant and the BAO measurements from the Ly-alpha forest of high-redshift quasars.
We employ density functional theory using the modified Becke-Johnson (mBJ) approach to investigate the electronic and magneto-optical properties of N-doped NaTaO$_3$. The mBJ results reveal a half metallic nature of NaTaO$_2$N, in contrast to results obtained by the generalized gradient approximation. We find a giant polar Kerr rotation of 2.16$^{\circ}$ at 725 nm wave length (visible region), which is high as compared to other half metallic perovskites as well as to the prototypical half metal PtMnSb.
Cavity-based noise detection schemes are combined with ultrafast pulse shaping as a means to diagnose the spectral correlations of both the amplitude and phase noise of an ultrafast frequency comb. The comb is divided into ten spectral regions, and the distribution of noise as well as the correlations between all pairs of spectral regions are measured against the quantum limit. These correlations are then represented in the form of classical noise matrices, which furnish a complete description of the underlying comb dynamics. Their eigendecomposition reveals a set of theoretically predicted, decoupled noise modes that govern the dynamics of the comb. Finally, the matrices contain the information necessary to deduce macroscopic noise properties of the comb.
Bayesian model selection methods provide a self-consistent probabilistic framework to test the validity of competing scenarios given a set of data. We present a case study application to strong gravitational lens parametric models. Our goal is to select a homogeneous lens subsample suitable for cosmological parameter inference. To this end we apply a Bayes factor analysis to a synthetic catalog of 500 lenses with power-law potential and external shear. For simplicity we focus on double-image lenses (the largest fraction of lens in the simulated sample) and select a subsample for which astrometry and time-delays provide strong evidence for a simple power-law model description. Through a likelihood analysis we recover the input value of the Hubble constant to within 3\sigma statistical uncertainty. We apply this methodology to a sample of double image lensed quasars. In the case of B1600+434, SBS 1520+530 and SDSS J1650+4251 the Bayes' factor analysis favors a simple power-law model description with high statistical significance. Assuming a flat \LambdaCDM cosmology, the combined likelihood data analysis of such systems gives the Hubble constant H_0=76+15-5 km/s/Mpc having marginalized over the lens model parameters, the cosmic matter density and consistently propagated the observational errors on the angular position of the images. The next generation of cosmic structure surveys will provide larger lens datasets and the method described here can be particularly useful to select homogeneous lens subsamples adapted to perform unbiased cosmological parameter inference
The frequencies of three separate Cs fountain clocks and one Rb fountain clock have been compared to various hydrogen masers to search for periodic changes correlated with the changing solar gravitational potential at the Earth and boost with respect to the Cosmic Microwave Background (CMB) rest frame. The data sets span over more than eight years. The main sources of long-term noise in such experiments are the offsets and linear drifts associated with the various H-masers. The drift can vary from nearly immeasurable to as high as 1.3*10^-15 per day. To circumvent these effects we apply a numerical derivative to the data, which significantly reduces the standard error when searching for periodic signals. We determine a standard error for the putative Local Position Invariance (LPI) coefficient with respect to gravity for a Cs-Fountain H-maser comparison of 4.8*10^-6 and 10^-5 for a Rb-Fountain H-maser comparison. From the same data the putative boost LPI coefficients were measured to a precision of up to parts in 10^11 with respect to the CMB rest frame. By combining these boost invariance experiments to a Cryogenic Sapphire Oscillator versus H-maser comparison, independent limits on all nine coefficients of the boost violation vector with respect to fundamental constant invariance (fine structure constant, electron mass and quark mass respectively), were determined to a precision of parts up to 10^10.
We introduce Kadanoff-Ceva order-disorder operators in the quantum Ising model. This approach was first used for the classical planar Ising model and recently put back to the stage. This representation turns out to be equivalent to the loop expansion of Sminorv's fermionic observables and is particularly interesting due to its simple and compact formulation. Using this approach, we are able to extend different results known in the classical planar Ising model, such as the conformal invariance/covariance of correlations and the energy-density, to the spin-representation of the (1+1) dimensional quantum Ising model.
Multiferroic materials, in which ferroelectric and magnetic ordering coexist, are of fundamental interest for the development of novel memory devices that allow for electrical writing and non-destructive magnetic readout operation. The great challenge is to create room temperature multiferroic materials with strongly coupled ferroelectric and ferromagnetic (or ferrimagnetic) orderings. BiFeO3 has been the most heavily investigated single-phase multiferroic to date due to the coexistence of its magnetic order and ferroelectric order at room temperature. However, there is no net magnetic moment in the cycloidal (antiferromagnetic-like) magnetic state of bulk BiFeO3, which severely limits its realistic applications in electric field controlled spintronic devices. Here, we predict that double perovskite Zn2FeOsO6 is a new multiferroic with properties superior to BiFeO3. First, there are strong ferroelectricity and strong ferrimagnetism at room temperature in Zn2FeOsO6. Second, the easy-plane of the spontaneous magnetization can be switched by an external electric field, evidencing the strong magnetoelectric coupling existing in this system. Our results suggest that ferrimagnetic 3d-5d double perovskite may therefore be used to achieve voltage control of magnetism in future spintronic devices.
${\cal E}$ denotes the family of all finite nonempty $S\subseteq{\mathbb N}:=\{1,2,\ldots\}$, and ${\cal E}(X):={\cal E}\cap\{S:S\subseteq X\}$ when $X\subseteq{\mathbb N}$. Similarly, ${\cal F}$ denotes the family of all finite nonempty $T\subseteq{\mathbb Q}^+$, and ${\cal F}(Y) := {\cal F}\cap\{T:T\subseteq Y\}$ where ${\mathbb Q}^+$ is the set of all positive rationals and $Y\subseteq{\mathbb Q}^+$.   This paper treats the functions $\sigma:{\cal E}\rightarrow{\mathbb Q}^+$ given by $\sigma:S\mapsto\sigma S :=\sum\{1/x:x\in S\}$, the function $\delta:{\cal E}\rightarrow{\mathbb N}$ defined by $\sigma S = \nu S/\delta S$ where the integers $\nu S$ and $\delta S$ are coprime, and the more general function $\Sigma:{\cal F}\rightarrow{\mathbb Q}^+$ where $\Sigma T$ denotes the sum of the elements in $T$ for $T\in{\cal F}$.   Theorem 1.1. For each $r\in{\mathbb Q}^+$, there exists an infinite pairwise disjoint subfamily ${\cal H}_r\subseteq{\cal E}$ such that $r=\sigma S$ for all $S\in{\cal H}_r$.   Theorem 1.2. Let $X$ be a pairwise coprime set of positive integers. Then $\sigma$ restricted to ${\cal E}(X)$ and $\delta$ restricted to ${\cal E}(X)$ are injective. Also, $\sigma C\in{\mathbb N}$ for $C\in{\cal E}(X)$ only if $C=\{1\}$.   Theorem 6.5. There is a set $X$ of positive rational numbers for which $\Sigma:{\cal F}(X)\rightarrow{\mathbb Q}^+$ is a surjection, but for which $1\in X$ and   the only $S\in{\cal F}(X)$ with $\Sigma S = 1$ is $S = \{1\}$.
We emphasise the relation between the spin structure of the proton and the axial U(1) problem. New experiments motivated by the proton spin problem which could shed light on the nature of U(1) symmetry breaking in QCD are discussed.
We write down and solve equations describing steady state, optically thin, advection-dominated accretion onto a Kerr black hole. The mean flow, described by the relativistic fluid equations, is axisymmetric and vertically averaged. The effect of turbulence in the flow is represented by a viscous shear stress. Our treatment differs in several important ways from earlier work: we use a causal prescription for the shear stress, we do not assume the relativistic enthalpy is unity (this is important for rapidly rotating holes), and we use a relativistic equation of state. We present several representative solutions and use them to evaluate the importance of relativistic effects, to check our approximations, and to evaluate the robustness of the input physics. Detailed properties of the solutions are described in an accompanying paper.
We explore the implications for the high redshift universe of ``state-of-the-art'' models for the chemical and spectrophotometric evolution of spiral galaxies. The models are based on simple ``scaling relations'' for discs, obtained in the framework of Cold Dark Matter models for galaxy formation, and were ``calibrated'' as to reproduce the properties of the Milky Way and of nearby discs (at redshift z~0). In this paper, we compare the predictions of our ``hybrid'' approach to galaxy evolution to observations at moderate and high redshift. We find that the models are in fairly good agreement with observations up to z~1, while some problems appear at higher redshift (provided there is no selection bias in the data); these discrepancies may suggest that galaxy mergers (not considered in this work) played a non negligible role at z>1. We also predict the existence of a ``universal'' correlation between abundance gradients and disc scalelengths, independent of redshift.
(Abridged) We use Subaru data to conduct a detailed weak-lensing study of the dark matter distribution in a sample of 30 X-ray luminous galaxy clusters at 0.15<z<0.3. A weak-lensing signal is detected at high statistical significance in each cluster, the total detection S/N ranging from 5 to 13. In this paper we concentrate on fitting spherical models to the tangential distortion profiles of the clusters. When the models are fitted to the clusters individually, we are unable to discriminate statistically between SIS and NFW models. However when the tangential distortion profiles of the individual clusters are combined, and models fitted to the stacked profile, the SIS model is rejected at 6- and 11-sigma, respectively, for low- and high-mass bins. We also use the individual cluster NFW model fits to investigate the relationship between cluster mass (M_vir) and concentration (c_vir), finding an anti-correlation of c_vir and M_vir. The best-fit c_vir-M_vir relation is: c_vir(M_vir) propto M_vir^{-alpha} with alpha=0.41+/-0.19 -- i.e. a non-zero slope is detected at 2sigma significance. We then investigate the optimal radius within which to measure cluster mass, finding that the typical fractional errors are improved to sigma(M_Delta)/M_Delta ~ 0.1-0.2 for cluster masses at higher over-densities Delta=500-2000, from 0.2-0.3 for the virial over-density (~110). Further comparisons between mass measurements based on spherical model fitting and the model-independent aperture mass method reveal that the 2D aperture mass enclosed within a cylinder of a given aperture radius is systematically greater than the 3D spherical mass obtained from NFW model fitting: M_2D/M_3D= 1.34 and 1.40 for Delta=500 and 110, respectively. The amplitude of this effect agrees well with that predicted by integrating the NFW model along the line-of-sight.
Recent solar spectroscopic observations have shown that coronal spectral lines can exhibit asymmetric profiles, with enhanced emissions at their blue wings. These asymmetries correspond to rapidly upflowing plasmas at speeds exceeding ~ 50 km/s. Here, we perform a study of the density of the rapidly upflowing material and compare it to that of the line core which corresponds to the bulk of the plasma. For this task we use spectroscopic observations of several active regions taken by the Extreme Ultraviolet Imaging Spectrometer of the Hinode mission. The density sensitive ratio of the Fe XIV lines at 264.78 and 274.20 A is used to determine wing and core densities. We compute the ratio of the blue wing density to the core density and find that most values are of order unity. This is consistent with the predictions for coronal nanoflares if most of the observed coronal mass is supplied by chromospheric evaporation driven by the nanoflares. However, much larger blue wing-to-core density ratios are predicted if most of the coronal mass is supplied by heated material ejected with type II spicules. Our measurements do not rule out a spicule origin for the blue wing emission, but they argue against spicules being a primary source of the hot plasma in the corona. We note that only about 40% of the pixels where line blends could be safely ignored have blue wing asymmetries in both Fe XIV lines. Anticipated sub-arcsecond spatial resolution spectroscopic observations in future missions could shed more light on the origin of blue, red, and mixed asymmetries.
Dynamic properties of a one-dimensional probabilistic cellular automaton are studied by monte-carlo simulation near a critical point which marks a second-order phase transition from a active state to a effectively unique absorbing state. Values obtained for the dynamic critical exponents indicate that the transition belongs to the universality class of directed percolation. Finally the model is compared with a previously studied one to show that a difference in the nature of the absorbing states places them in different universality classes.
Existing video prediction methods mainly rely on observing multiple historical frames or focus on predicting the next one-frame. In this work, we study the problem of generating consecutive multiple future frames by observing one single still image only. We formulate the multi-frame prediction task as a multiple time step flow (multi-flow) prediction phase followed by a flow-to-frame synthesis phase. The multi-flow prediction is modeled in a variational probabilistic manner with spatial-temporal relationships learned through 3D convolutions. The flow-to-frame synthesis is modeled as a generative process in order to keep the predicted results lying closer to the manifold shape of real video sequence. Such a two-phase design prevents the model from directly looking at the high-dimensional pixel space of the frame sequence and is demonstrated to be more effective in predicting better and diverse results. Extensive experimental results on videos with different types of motion show that the proposed algorithm performs favorably against existing methods in terms of quality, diversity and human perceptual evaluation.
We develop a framework to modify the Bogomolov-Gieseker type inequality conjecture introduced by Bayer-Macri-Toda, in order to construct a family of geometric Bridgeland stability conditions on any smooth projective 3-fold. We show that it is enough to check these modified inequalities on a small class of tilt stable objects. We extend some of the techniques in the works by Li and Bernardara-Macri-Schmidt-Zhao to formulate a strong form of Bogomolov-Gieseker inequality for tilt stable objects on Fano 3-folds. Consequently, we establish our modified Bogomolov-Gieseker type inequality conjecture for general Fano 3-folds, including an optimal inequality for the blow-up of $P^3$ at a point.
We explore the implications of a single observer's viewpoint on measurements of galaxy clustering statistics. We focus on the Bardeen potentials, which imprint characteristic scale-dependent signatures in the observed galaxy power spectrum. The existence of an observer breaks homogeneity as it singles out particular field values at her/his position, like a spontaneous symmetry breaking. As a result, spatial averaging of the data must be performed while holding the Bardeen potentials fixed at the observer's position. In practice, this can be implemented with the formalism of constrained random fields. In the traditional Cartesian Fourier decomposition, this constraint imprints a signature in the observed galaxy power spectrum at wavenumber comparable to the fundamental mode of the survey. This effect, which is well within the cosmic variance, is the same for all observers regardless of their local environment because differences of potential solely are observable. In a spherical Bessel Fourier decomposition, this constraint affects the monopole of the observed galaxy distribution solely, like in CMB data. As a corollary, the scale-dependence of the non-Gaussian bias induced by a local primordial non-Gaussianity is not significantly affected by the observer's viewpoint.
Magnetic translation groups are considered as central extensions of the translation group T=Z^n by the group of factors (a~gauge group) U(1). The obtained general formulae allow to consider a magnetic field as an~antisymmetric tensor (of rank 2) and factor systems are determined by a transvection of this tensor with a tensor product t \otimes t'.
Affine varieties of dimension greater than two can be explored their structures with the help of fibrations by the affine line or plane and quotient morphisms by $\mathbb{G}_a$-actions. We consider $\mathbb{G}_a$-actions on affine threefolds and discuss the structure and the singularities of the quotient surface as well as the singular fibers of the quotient morphism. Relative $\mathbb{G}_a$ and $\mathbb{G}_m$-actions on $\mathbb{A}^4$ or on an affine 4-fold having $\mathbb{A}^3$-fibrations over $\mathbb{A}^1$ are discussed when the actions leave one variable invariant or the fibration invariant.
We report a detailed theoretical study of the electronic structure, spectral properties, and lattice parameters of bulk FeSe under pressure using a fully charge self-consistent implementation of the density functional theory plus dynamical mean-field theory method (DFT+DMFT). In particular, we perform a structural optimization and compute the evolution of the lattice parameters (volume, $c/a$ ratio, and the internal $z$ position of Se) and the electronic structure of the tetragonal (space group $P4/nmm$) paramagnetic FeSe. Our results for the lattice parameters are in good quantitative agreement with experiment. The $c/a$ ratio is slightly overestimated by about $3$~\%, presumably due to the absence of the van der Waals interactions between the FeSe layers in our calculations. The lattice parameters determined within DFT are off the experimental values by a remarkable $\sim$$6$-$15$~\%, implying a crucial importance of electron correlations. Upon compression to $10$~GPa, the $c/a$ ratio and the lattice volume show a decrease by $2$ and $10$~\%, respectively, while the Se $z$ coordinate weakly increases by $\sim$$2$~\%. Most importantly, our results reveal a topological change of the Fermi surface (Lifshitz transition) which is accompanied by a two- to three-dimensional crossover. Our results indicate a small reduction of the quasiparticle mass renormalization $m^*/m$ by about $5$~\% for the $e$ and less than $1$~\% for the $t_2$ states, as compared to ambient pressure. The behavior of the momentum-resolved magnetic susceptibility $\chi({\bf q})$ shows no topological changes of magnetic correlations under pressure, but demonstrates a reduction of the degree of the in-plane $(\pi,\pi)$ stripe-type nesting. Our results for the electronic structure and lattice parameters of FeSe are in good qualitative agreement with recent experiments on its isoelectronic counterpart FeSe$_{1-x}$S$_x$.
The Weisberger relation, an exact statement of the parton model, elegantly relates a high-energy physics observable, the 1/x moment of parton distribution functions, to a nonperturbative low-energy observable: the dependence of the nucleon mass on the value of the quark mass or its corresponding quark condensate. We show that contemporary fits to nucleon structure functions fail to determine this 1/x moment; however, deeply virtual Compton scattering can be described in terms of a novel F_{1/x}(t) form factor which illuminates this physics. An analysis of exclusive photon-induced processes in terms of the parton-nucleon scattering amplitude with Regge behavior reveals a failure of the high Q^2 factorization of exclusive processes at low t in terms of the Generalized Parton-Distribution Functions which has been widely believed to hold in the past. We emphasize the need for more data for the DVCS process at large t in future or upgraded facilities.
The Reissner-Nordstr\"om black hole solution in a generic cosmological constant background in the the context of Rastall gravity is obtained. It is shown that the cosmological constant arises naturally from the consistency of the non-vacuum field equations of the Rastall theory for a spherical symmetric spacetime, rather than its {\it ad-hoc} introduction in the usual Einstein and Einstein-Maxwell field equations. The usual Reissner-Nordstr\"om, Schwarzschild and Schwarzschild-(anti)de Sitter black hole solutions in the framework of this theory are also addressed as the special independent subclasses of the obtained general solution.
We have investigated the atomically-resolved substrate and homoepitaxial thin film surfaces of SrTiO3(001) using low-temperature scanning tunneling microscopy/spectroscopy (STM/STS) combined with pulsed laser deposition (PLD). It was found that annealing at 1000 oC in an oxygen partial pressure of 1*10-6 Torr, which is a typical annealing treatment for the preparation of SrTiO3 substrates, unexpectedly resulted in a disordered surface on an atomic scale. In contrast, homoepitaxial SrTiO3 thin films grown on this disordered substrate exhibited (2*2) surface reconstructions. The differential conductance spectra, dI/dV in STS measurements, revealed a number of surface defects in a 10-unit-cell-thick SrTiO3 film, but much fewer in a 50-unit-cell-thick film. These results indicate that the defect density in the film strongly depends on the film thickness, suggesting non-uniform stoichiometry along the growth direction.