ShantanuT01/DACTYL-Pretraining huggingface dataset:
We study how to generate captions that are not only accurate in describing an image but also discriminative across different images. The problem is both fundamental and interesting, as most machine-generated captions, despite phenomenal research progresses in the past several years, are expressed in a very monotonic and featureless format. While such captions are normally accurate, they often lack important characteristics in human languages - distinctiveness for each caption and diversity for different images. To address this problem, we propose a novel conditional generative adversarial network for generating diverse captions across images. Instead of estimating the quality of a caption solely on one image, the proposed comparative adversarial learning framework better assesses the quality of captions by comparing a set of captions within the image-caption joint space. By contrasting with human-written captions and image-mismatched captions, the caption generator effectively exploits the inherent characteristics of human languages, and generates more discriminative captions. We show that our proposed network is capable of producing accurate and diverse captions across images.
In this paper we investigate the Bose-Einstein condensation of massive spin-1 particles in an Einstein universe. The system is considered under relativistic conditions taking into consideration the possibility of particle-antiparticle pair production. An exact expression for the charge density is obtained, then certain approximations are employed in order to obtain the solutions in closed form. A discussion of the approximations employed in this and other work is given. The effects of finite-size and spin-curvature coupling are emphasized.
Recently, a new approach for solving the three-body problem for (d,p) reactions in the Coulomb-distorted basis in momentum space was proposed. Important input quantities for such calculations are the scattering matrix elements for proton- and neutron-nucleus scattering. We present a generalization of the Ernst-Shakin-Thaler scheme in which a momentum space separable representation of proton-nucleus scattering matrix elements can be calculated in the Coulomb basis. The viability of this method is demonstrated by comparing S-matrix elements obtained for p$+^{48}$Ca and p$+^{208}$Pb for a phenomenological optical potential with corresponding coordinate space calculations.
As a planet transits the face of a star, it accelerates along the line-of-sight. The changing delay in the propagation of photons produces an apparent deceleration of the planet across the sky throughout the transit. This persistent transverse deceleration breaks the time-reversal symmetry in the transit lightcurve of a spherical planet in a circular orbit around a perfectly symmetric star. For `hot Jupiter' systems, ingress advances at a higher rate than egress by a fraction of 10^{-4}-10^{-3}. Forthcoming space telescopes such as Kepler or COROT will reach the sensitivity required to detect this asymmetry. The scaling of the fractional asymmetry with stellar mass M and planetary orbital radius R as M/R^2 is different from the scaling of the orbital period as (M/R^3)^{-1/2}. Therefore, this effect constitutes a new method for a purely dynamical determination of the mass of the star, which is currently inferred indirectly with theoretical uncertainties based on spectral modeling. Radial velocity data for the reflex motion of the star can then be used to determine the planet's mass. Although orbital eccentricity could introduce a larger asymmetry than the light propagation delay, the eccentricity is expected to decay by tidal dissipation to negligible values for a close-in planet with no perturbing third body. Future detection of the eclipse of a planet's emission by its star could be used to measure the light propagation delay across the orbital diameter, 46.7(R/7x10^{11}cm) seconds, and also determine the stellar mass from the orbital period.
Existing quantum cryptography is resistant against secrecy-breaking quantum computers but suffers fast decay of the signal at long distances. The various types of repeaters of propagating quantum states have been developed to meet the challenge, but the problem is far from being solved. We step in the breach and put forth long-distance high secrecy optical cryptography, creating the fast quantum key distribution over distances up to 40,000 kilometers. The key element of the proposed protocol is the physical control over the transmission line.
The MeerKAT Exploration of Relics, Giant Halos, and Extragalactic Radio Sources (MERGHERS) survey is a planned project to study a large statistical sample of galaxy clusters with the MeerKAT observatory. Here we present the results of a 16--hour pilot project, observed in response to the 2019 MeerKAT Shared Risk proposal call, to test the feasibility of using MeerKAT for a large cluster study using short (0.2--2.1\,hour) integration times. The pilot focuses on 1.28\,GHz observations of 13 massive, low-to-intermediate redshift ($0.22 < z < 0.65$) clusters from the Sunyaev-Zel'dovich-selected Atacama Cosmology Telescope (ACT) DR5 catalogue that show multiwavelength indications of dynamical disturbance. With a 70 per cent detection rate (9/13 clusters), this pilot study validates our proposed MERGHERS observing strategy and provides twelve detections of diffuse emission, eleven of them new, indicating the strength of MeerKAT for such types of studies. The detections (signal-to-noise ratio $\gtrsim6$) are summarised as follows: two systems host both relic(s) and a giant radio halo, five systems host radio halos, and two have candidate radio halos. Power values, $k$-corrected to 1.4 GHz assuming a fiducial spectral index of $\alpha = -1.3 \pm 0.4$, are consistent with known radio halo and relic scaling relations.
The neutrino-nucleon --> lepton pion QE reaction on the A-target is used as a signal event or/and to reconstruct the neutrino energy, using two-body kinematics. Competition of another processes could lead to misidentification of the arriving neutrinos, being important the fake events coming from the CC1-pion background. A precise knowledge of cross sections is a prerequisite in order to make simulations in event generators to substract the fake ones from the QE countings, and in this contribution we analyze the different nuclear effects on the CC1-pion channel. Our calculations also can be extended for the NC case.
Although we have yet to determine whether the DAMA data represents a true discovery of new physics, among such interpretations inelastic dark matter (IDM) can match the energy spectrum of DAMA very well while not contradicting the results of other direct detection searches. In this paper we investigate the general properties that a viable IDM candidate must have and search for simple models that realize these properties in natural ways. We begin by determining the regions of IDM parameter space that are allowed by direct detection searches including DAMA, paying special attention to larger IDM masses. We observe that an inelastic dark matter candidate with electroweak interactions can naturally satisfy observational constraints while simultaneously yielding the correct thermal relic abundance. We comment on several other proposed dark matter explanations for the DAMA signal and demonstrate that one of the proposed alternatives -- elastic scattering of dark matter off electrons -- is strongly disfavored when the modulated and unmodulated DAMA spectral data are taken into account. We then outline the general essential features of IDM models in which inelastic scattering off nuclei is mediated by the exchange of a massive gauge boson, and construct natural models in the context of a warped extra dimension and supersymmetry.
A widely adopted theoretical scheme to account for the neutrino oscillation phenomena is the see-saw mechanism together with the ``lopsided'' mass matrices, which is generally realized in the framework of supersymmetric grand unification. We will show that this scheme leads to large lepton flavor violation at low energy if supersymmetry is broken at the GUT or Plank scale. Especially, the branching ratio of $\mu\to e\gamma$ already exceeds the present experimental limit. We then propose a phenomenological model, which can account for the LMA solution to the solar neutrino problem and at the same time predict branching ratio of $\mu\to e\gamma$ below the present limit.
Electric field dynamics at a positive ion imbedded in an electron gas is considered using a semiclassical description. The dependence of the field autocorrelation function on charge number is studied for strong ion-electron coupling via MD simulation. The qualitative features for larger charge numbers are a decreasing correlation time followed by an increasing anticorrelation. Stopping power and related transport coefficients determined by the time integral of this correlation function result from the competing effects of increasing initial correlations and decreasing dynamical correlations. An interpretation of the MD results is obtained from an effective single particle model showing good agreement with the simulation results.
We derive the quantum stochastic master equation for bosonic systems without measurement theory but control theory. It is shown that the quantum effect of the measurement can be represented as the correlation between dynamical and measurement noise. The transfer function representation allows us to analyze a dynamical uncertainty relation which imposes strong constraints on the dynamics of the linear quantum systems. In particular, quantum systems preserving the minimum uncertainty are uniquely determined. For large spin systems, it is shown that local dynamics are equivalent to bosonic systems. Considering global behavior, we find quantum effects to which there is no classical counterparts. A control problem of producing maximal entanglement is discussed as the stabilization of a filtering process.
We consider boundary value problems for semilinear hyperbolic systems of the type $$ \partial_tu_j + a_j(x,\la)\partial_xu_j + b_j(x,\la,u) = 0, \; x\in(0,1), \;j=1,\dots,n $$ with smooth coefficient functions $a_j$ and $b_j$ such that $b_j(x,\la,0) = 0$ for all $x \in [0,1]$, $\la \in \R$, and $j=1,\ldots,n$. We state conditions for Hopf bifurcation, i.e., for existence, local uniqueness (up to phase shifts), smoothness and smooth dependence on $\la$ of time-periodic solutions bifurcating from the zero stationary solution. Furthermore, we derive a formula which determines the bifurcation direction.   The proof is done by means of a Liapunov-Schmidt reduction procedure. For this purpose, Fredholm properties of the linearized system and implicit function theorem techniques are used.   There are at least two distinguishing features of Hopf bifurcation theorems for hyperbolic PDEs in comparison with those for parabolic PDEs or for ODEs: First, the question if a non-degenerate time-periodic solution depends smoothly on the system parameters is much more delicate. And second, a sufficient amount of dissipativity is needed in the system, and a priori it is not clear how to verify this in terms of the data of the PDEs and of the boundary conditions.
We extend the Golec-Biernat-W\"usthoff model for virtual photon - proton scattering to include the resolved photon component explicitly. The parameters of the resolved photon component are taken from the literature, while the parameters of the dipole-nucleon interaction are fitted to the HERA data in a selected limited range of $x$ and $Q^2$. A good agreement with experimental data is obtained far beyond the region of the fit.
We investigate non-locality distillation using measures of non-locality based on the Elitzur-Popescu-Rohrlich decomposition. For a certain number of copies of a given non-local correlation, we define two quantities of interest: (i) the non-local cost, and (ii) the distillable non-locality. We find that there exist correlations whose distillable non-locality is strictly smaller than their non-local cost. Thus non-locality displays a form of irreversibility which we term bound non-locality. Finally we show that non-local distillability can be activated.
We study the effect of oxygen vacancies on the electronic structure of the model strongly correlated metal SrVO$_3$. By means of angle-resolved photoemission (ARPES) synchrotron experiments, we investigate the systematic effect of the UV dose on the measured spectra. We observe the onset of a spurious dose-dependent prominent peak at an energy range were the lower Hubbard band has been previously reported in this compound, raising questions on its previous interpretation. By a careful analysis of the dose dependent effects we succeed in disentangling the contributions coming from the oxygen vacancy states and from the lower Hubbard band. We obtain the intrinsic ARPES spectrum for the zero-vacancy limit, where a clear signal of a lower Hubbard band remains. We support our study by means of state-of-the-art ab initio calculations that include correlation effects and the presence of oxygen vacancies. Our results underscore the relevance of potential spurious states affecting ARPES experiments in correlated metals, which are associated to the ubiquitous oxygen vacancies as extensively reported in the context of a two-dimensional electron gas (2DEG) at the surface of insulating $d^0$ transition metal oxides.
We present radial velocities and [Fe/H] abundances for 340 stars in the Fornax dwarf spheroidal from R~16,000 spectra. The targets have been obtained in the outer parts of the galaxy, a region which has been poorly studied before. Our sample shows a wide range in [Fe/H], between -0.5 and -3.0 dex, in which we detect three subgroups. Removal of stars belonging to the most metal-rich population produces a truncated metallicity distribution function that is identical to Sculptor, indicating that these systems have shared a similar early evolution, only that Fornax experienced a late, intense period of star formation (SF). The derived age-metallicity relation shows a fast increase in [Fe/H] at early ages, after which the enrichment flattens significantly for stars younger than ~8 Gyr. Additionally, the data indicate a strong population of stars around 4 Gyr, followed by a second rapid enrichment in [Fe/H]. A leaky-box chemical enrichment model generally matches the observed relation but does not predict a significant population of young stars nor the strong enrichment at late times. The young population in Fornax may therefore originate from an externally triggered SF event. Our dynamical analysis reveals an increasing velocity dispersion with decreasing [Fe/H] from sigma_sys 7.5 km/s to >14 km/s, indicating an outside-in star formation history in a dark matter dominated halo. The large velocity dispersion at low metallicities is possibly the result of a non-Gaussian velocity distribution amongst stars older than ~8 Gyr. Our sample also includes members from the Fornax GCs H2 and H5. In agreement with past studies we find [Fe/H]=-2.04+-0.04 and a mean radial velocity RV=59.36+-0.31 km/s for H2 and [Fe/H]=-2.02+-0.11 and RV=59.39+-0.44 km/s for H5. Overall, we find large complexity in the chemical and dynamical properties, with signatures that additionally vary with galactocentric distance.
While scale-invariant modeling has substantially boosted the performance of visual recognition tasks, it remains largely under-explored in deep networks based image restoration. Naively applying those scale-invariant techniques (e.g. multi-scale testing, random-scale data augmentation) to image restoration tasks usually leads to inferior performance. In this paper, we show that properly modeling scale-invariance into neural networks can bring significant benefits to image restoration performance. Inspired from spatial-wise convolution for shift-invariance, "scale-wise convolution" is proposed to convolve across multiple scales for scale-invariance. In our scale-wise convolutional network (SCN), we first map the input image to the feature space and then build a feature pyramid representation via bi-linear down-scaling progressively. The feature pyramid is then passed to a residual network with scale-wise convolutions. The proposed scale-wise convolution learns to dynamically activate and aggregate features from different input scales in each residual building block, in order to exploit contextual information on multiple scales. In experiments, we compare the restoration accuracy and parameter efficiency among our model and many different variants of multi-scale neural networks. The proposed network with scale-wise convolution achieves superior performance in multiple image restoration tasks including image super-resolution, image denoising and image compression artifacts removal. Code and models are available at: https://github.com/ychfan/scn_sr
In this article, we present the application of the weighted horizontal gradient of magnetic field (WGM) flare prediction method to 3-dimensional (3D) extrapolated magnetic configurations of 13 flaring solar active regions (ARs). The main aim is to identify an optimal height range, if any, in the interface region between the photosphere and lower corona, where the flare onset time prediction capability of WGM is best exploited. The optimal height is where flare prediction, by means of the WGM method, is achieved earlier than at the photospheric level. 3D magnetic structures, based on potential and non-linear force-free field extrapolations, are constructed to study a vertical range from the photosphere up to the low corona with a 45 km step size. The WGM method is applied as a function of height to all 13 flaring AR cases that are subject to certain selection criteria. We found that applying the WGM method between 1000 and 1800 km above the solar surface would improve the prediction of the flare onset time by around 2-8 hours.Certain caveats and an outlook for future work along these lines are also discussed.
I consider the uncertainties in parton distributions and the consequences for hadronic cross-sections. There is ever-increasing sophistication in the relationship between the uncertainties of the distributions and the errors on the experimental data used to extract them. However, I demonstrate that this uncertainty is frequently subsumed by that due to the choice of data used in fits, and more surprisingly by the precise details of the theoretical framework used. Variations in heavy flavour prescriptions provide striking examples.
These notes summarize lectures given at the 2019 Les Houches summer school on Quantum Information Machines. They describe and review an application of quantum metrology concepts to searches for ultralight dark matter. In particular, for ultralight dark matter that couples as a weak classical force to a laboratory harmonic oscillator, quantum squeezing benefits experiments in which the mass of the dark matter particle is unknown. This benefit is present even if the oscillatory dark matter signal is much more coherent than the harmonic oscillator that it couples to, as is the case for microwave frequency searches for dark matter axion particles.
The magnetic moments of the negative parity octet resonances with spin {1/2}: $N^*$(1535), $N^*$(1650), $\Sigma^*$(1620), and $\Xi^*$(1690) have been calculated within the framework of the chiral constituent quark model. In this approach, the presence of the polarized $q\bar{q}$ pairs (or the meson cloud, in other words) is considered by using the Lagrangian for Goldstone boson emission from the constituent quarks. Further, the explicit contributions coming from the spin and orbital angular momentum, including the effects of the configurations mixing between the states with different spins, are obtained. The motivation for these calculations comes from the recent interest in experimental measurement of the magnetic moment of the ${S_{11}(1535)}$ resonance and of similar calculations being done within lattice quantum chromodynamics approaches. Our results can be compared with those expected to come from these sources.
Deep inelastic structure functions for the nucleon are obtained in a constituent quark model on the light cone. In the Bjorken limit the parton model is derived. Structure functions from the hadronic tensor at the scale $\mu \sim 0.25$ GeV are evolved from (0.6 GeV$)^{2}$ to $-q^{2}\sim 15$ GeV$^{2}$. The model incorporates the quark boosts, is designed to describe form factors and structure functions, and to provide a link between the parton and constituent quark models. The main effect of the spin force between quarks is described in terms of smaller (and lighter) scalar $u-d$ quark pairs in the nucleon. To account for the negative slope of $F^{n}_{2}(x)/F^{p}_{2}(x)$, attraction between scalar $u-d$ quark pairs and incorporation of boosts are required. The two-body spin force between quarks from color magnetism also leads to a negative slope. The polarization asymmetry $A^{p}_{1}$ is in fair agreement with the EMC data in the valence quark region. Revised hep-ph/9401342, Phys. Rev. D.
Recent observations show that the Milky Way's metallicity distribution function (MDF) changes its shape as a function of radius. This new evidence of radial migration within the stellar disc sets additional constraints on Galactic models. By performing controlled test particle simulations in a very detailed, observationally motivated model of the Milky Way, we demonstrate that, in the inner region of the disc, the MDF is shaped by the joint action of the bar and spiral arms, while at outer radii the MDF is mainly shaped by the spiral arms. We show that the spiral arms are able to imprint their signature in the radial migration, shaping the MDF in the outskirts of the Galactic disc with a minimal participation of the bar. Conversely, this work has the potential to characterise some structural and dynamical parameters of the spiral arms based on radial migration and the shape of the MDF. Finally, the resemblance obtained with this approximation to the MDF curves of the Galaxy as seen by APOGEE, show that a fundamental factor influencing their shape is the Galactic potential.
We investigate holographic s-wave superconductors with nonlinear arcsin-electrodynamics in the background of Schwarzschild anti-de Sitter black holes. The analytical Sturm-Liouville eigenvalue problem is explored and we assume that the scalar and electromagnetic fields do not influence on the background metric (the probe limit). The critical temperatures of phase transitions depending on the parameter of the model is obtained. We show that in our case the condensation formation becomes easier compared to Born-Infeld nonlinear electrodynamics. The critical exponent near the critical temperature is calculated which is 1/2. With the help of the matching method we derive analytic expressions for the condensation value and the critical temperature. The real and imaginary parts of the conductivity in our model, making use of an analytical method, are computed.