ShantanuT01/DACTYL-Pretraining huggingface dataset:
The energies as a function of the magnetic field ($H$) and the pressure are studied theoretically in the tight-binding model for the two-dimensional organic conductor,   $\alpha$-(BEDT-TTF)$_2$I$_3$, in which massless Dirac fermions are realized. The effects of the uniaxial pressure ($P$) are studied by using the pressure-dependent hopping parameters. The system is semi-metallic with the same area of an electron pocket and a hole pocket at $P < 3.0$~kbar, where the energies $(\varepsilon_{\rm D}^0$) at the Dirac points locate below the Fermi energy $(\varepsilon_{\rm F}^0$) when $H=0$. We find that at $P=2.3$~kbar the Dirac cones are critically tilted. In that case a new type of band crossing occurs at "three-quarter"-Dirac points, i.e., the dispersion is quadratic in one direction and linear in the other three directions. We obtain new magnetic-field-dependences of the Landau levels $(\varepsilon_n)$; $\varepsilon_n-\varepsilon^0_{\textrm{D}} \propto (n H)^{4/5}$ at $P=2.3$~kbar ("three-quarter"-Dirac points) and $|\varepsilon_n-\varepsilon_{\rm F}^0| \propto (n H)^2$ at $P=3.0$~kbar (the critical pressure for the semi-metallic state). We also study the magnetization as a function of the inverse magnetic field. We obtain two types of quantum oscillations. One is the usual de Haas van Alphen (dHvA) oscillation, and the other is the unusual dHvA-like oscillation which is seen even in the system without the Fermi surface.
We present two rotating black hole solutions with axion $\xi$, dilaton $\phi$ and two U(1) vector fields. By applying the "Newman-Janis trick" to a metric with 3 arbitrary parameters we find a rotating metric $g_{\mu\nu}$ with 4 such parameters $(M, a, Q_E, Q_M)$, and then a solution with this $g_{\mu\nu}$ as metric. Our solution is asymptotically flat and has angular momentum $J=M a$, gyromagnetic ratio $g=2$, two horizons, the singularities of Kerr's solution, axion and dilaton singular only for $r=a\cos\theta=0$. Applying to the solution we have found the $S-$duality transformation we get a new solution, whose axion, dilaton and vector fields have one more parameter. The metric, each vector field and the $\lambda=\xi+ie^{-2\phi}$ of our solutions and the solution of : Sen for $Q_E$, Sen for $Q_E$ and $Q_M$, Kerr-Newman for $Q_E$ and $Q_M$, Kerr, Ref. 9, STW, GM-GHS, Reissner-Nordstr\"{o}m,Schwarzschild are the same function of $a$, and two functions $\rho^2=r(r+b)+a^2\cos^2\theta$ and $\Delta=\rho^2-2Mr+c$, of $a$, $b$ and two functions, and of $a$, $b$ and $d$ respectively, where $a$, $b$, $c$ and $d$ are constants. It is shown that from our solutions a number of known solutions can be obtained, which together with our solutions are listed in an Appendix. Also it is shown that all solutions which are mentioned in the paper satisfy all energy conditions, and mass formulae are obtained for them.
The role of neutron-proton pairing correlations on the structure of nuclei along the $N=Z$ line is reviewed. Particular emphasis is placed on the competition between isovector ($T=1$) and isoscalar $(T=0$) pair fields. The expected properties of these systems, in terms of pairing collective motion, are assessed by different theoretical frameworks including schematic models, realistic Shell Model and mean field approaches. The results are contrasted with experimental data with the goal of establishing clear signals for the existence of neutron-proton ($np$) condensates. We will show that there is clear evidence for an isovector $np$ condensate as expected from isospin invariance. However, and contrary to early expectations, a condensate of deuteron-like pairs appears quite elusive and pairing collectivity in the $T=0$ channel may only show in the form of a phonon. Arguments are presented for the use of direct reactions, adding or removing an $np$ pair, as the most promising tool to provide a definite answer to this intriguing question.
We study a novel type of extensions of the Standard Model which include a hard mass term for the U(1) gauge field and, optionally, the additional scalar multiplets spontaneously violating the electric charge conservation. Contrary to the case of abelian massive electrodynamics, in these theories the massiveness of photon necessarily implies non-conservation (and also dequantization) of the electric charge (even in the absence of spontaneous breakdown of the electromagnetic symmetry). On the other hand, unexpectedly, there exist models with charge non-conservation where it is possible to keep the photon mass zero (at least, at the tree level).
Context. Multi-wavelength observations of gamma-ray burst (GRB) afterglows provide important information about the activity of their central engines and their environments. In particular, the short timescale variability, such as bumps and/or rebrightening features visible in the multi-wavelength light curves, is still poorly understood.   Aims. We analyze the multi-wavelength observations of the GRB100219A afterglow at redshift 4.7. In particular, we attempt to identify the physical origin of the late achromatic flares/bumps detected in the X-ray and optical bands.   Methods. We present ground-based optical photometric data and Swift X-ray observations on GRB100219A. We analyzed the temporal behavior of the X-ray and optical light curves, as well as the X-ray spectra.   Results. The early flares in the X-ray and optical light curves peak simultaneously at about 1000 s after the burst trigger, while late achromatic bumps in the X-ray and optical bands appear at about 20000 s after the burst trigger. These are uncommon features in the afterglow phenomenology. Considering the temporal and spectral properties, we argue that both optical and X-ray emissions come from the same mechanism. The late flares/bumps may be produced by late internal shocks from long-lasting activity of the central engine. An off-axis origin for a structured jet model is also discussed to interpret the bump shapes. The early optical bump can be interpreted as the afterglow onset, while the early X-ray flare could be caused by the internal activity. GRB 100219A exploded in a dense environment as revealed by the strong attenuation of X-ray emission and the optical-to-X-ray spectral energy distribution.
Twenty-one new optical light curves, including five curves obtained in 2009 and sixteen curves detected from the AAVSO International Database spanning from 1977 to 2011, demonstrate 16 new primary minimum light times in the high state. Furthermore, seven newly found low-state transient events from 2006 to 2009 were discovered, consisting of five Gaussian-shaped events and two events with an exponential form with decay timescales of $<$0.005 days; these timescales are one order of magnitude shorter than those of previous X-ray flare events. In the state transition, two special events were detected: a "disrupted event" with an amplitude of $\sim$ 2 mag and a duration of $\sim$ 72 minutes and continuing R-band twin events larger than all known R-band flares detected in M-type red dwarfs. All 45 available high-state data points spanning over 35 yr were used to construct an updated O-C diagram of \objectname{AM Herculis}, which clearly shows a significant sine-like variation with a period of 12-15 yr and an amplitude of 6-9 minutes. Using the inspected physical parameters of the donor star, the secular variation in the O-C diagram cannot be interpreted by any decided angular momentum loss mechanism, but can satisfy the condition $\tau_{\dot{\rm M}_{2}}\simeq\tau_{\rm KH}>>\tau_{\dot{\rm R}_{\rm 2}}$, which is required by numerical calculations of the secular evolution of cataclysmic variables. In order to explain the prominent periodic modulation, three plausible mechanisms - spot motion, the light travel-time effect, and magnetic active cycles - are discussed in detail.
The renormalization group approach and the operator product expansion technique are applied to the model of a tracer field advected by the Navier-Stokes velocity ensemble for a compressible fluid. The model is considered in the vicinity of the specific space dimension $d=4$. The properties of the equal-time structure functions are investigated. The multifractal behaviour of various correlation functions is established. All calculations are performed in the leading one-loop approximation.
Multi-band near-infrared images of twelve BL Lacertae objects were obtained with the 2.5m telescope at the Las Campanas Observatory in order to determine the properties of their underlying host galaxies. Resolved emission was clearly detected in eight of the lowest redshift targets (up to z~0.3), and was modeled with a de Vaucouleurs r^{1/4} surface brightness law. We find that the morphologies match the elliptical galaxy profiles well, and that the BL Lac objects reside in large and luminous, but otherwise normal hosts -- consistent with previous studies done predominantly at optical wavelengths. The median absolute K-band magnitude of the galaxies in this study is -26.2, the average half-light radius is 4.2 +/- 2.3 kpc, and their average integrated R-K color is 2.7 +/- 0.3 mag. These are well within the range of values measured previously in the H-band by Kotilainen et al. and Scarpa et al. in a comparable number of targets. Taking their data together with our results, we find a best-fit K-band Kormendy relation of \mu_{e} = 4.3 log_{10} (r_{e}/kpc) + 14.2 mag arcsec^{-2}, virtually identical to that obtained for normal ellipticals. Finally, the near-infrared colors determined for five galaxies (average J-K = 0.8 +/- 0.3 mag) are the first such measurements for BL Lac hosts, and match those expected from old stellar populations at the BL Lac redshifts.
Understanding how the orbital motion of electrons is coupled to the spin degree of freedom in nanoscale systems is central for applications in spin-based electronics and quantum computation. We demonstrate this coupling of spin and orbit in a carbon nanotube quantum dot in the general multi-electron regime in presence of finite disorder. Further, we find a strong systematic dependence of the spin-orbit coupling on the electron occupation of the quantum dot. This dependence, which even includes a sign change is not demonstrated in any other system and follows from the curvature-induced spin-orbit split Dirac-spectrum of the underlying graphene lattice. Our findings unambiguously show that the spin-orbit coupling is a general property of nanotube quantum dots which provide a unique platform for the study of spin-orbit effects and their applications.
The long short-term memory (LSTM) neural network is capable of processing complex sequential information since it utilizes special gating schemes for learning representations from long input sequences. It has the potential to model any sequential time-series data, where the current hidden state has to be considered in the context of the past hidden states. This property makes LSTM an ideal choice to learn the complex dynamics of various actions. Unfortunately, the conventional LSTMs do not consider the impact of spatio-temporal dynamics corresponding to the given salient motion patterns, when they gate the information that ought to be memorized through time. To address this problem, we propose a differential gating scheme for the LSTM neural network, which emphasizes on the change in information gain caused by the salient motions between the successive frames. This change in information gain is quantified by Derivative of States (DoS), and thus the proposed LSTM model is termed as differential Recurrent Neural Network (dRNN). We demonstrate the effectiveness of the proposed model by automatically recognizing actions from the real-world 2D and 3D human action datasets. Our study is one of the first works towards demonstrating the potential of learning complex time-series representations via high-order derivatives of states.
We present new observations with the Atacama Large Millimeter/submillimeter Array for a gravitationally-lensed galaxy at $z=9.1$, MACS1149-JD1. [O III] 88-$\mu$m emission is detected at 10$\sigma$ with a spatial resolution of $\sim0.3$ kpc in the source plane, enabling the most distant morpho-kinematic study of a galaxy. The [O III] emission is distributed smoothly without any resolved clumps and shows a clear velocity gradient with $\Delta V_{\rm obs}/2\sigma_{\rm tot}=0.84\pm0.23$, where $\Delta V_{\rm obs}$ is the observed maximum velocity difference and $\sigma_{\rm tot}$ is the velocity dispersion measured in the spatially-integrated line profile, suggesting a rotating system. Assuming a geometrically thin self-gravitating rotation disk model, we obtain $V_{\rm rot}/\sigma_V=0.67_{-0.26}^{+0.73}$, where $V_{\rm rot}$ and $\sigma_V$ are the rotation velocity and velocity dispersion, respectively, still consistent with rotation. The resulting disk mass of $0.65_{-0.40}^{+1.37}\times10^{9}$ M$_\odot$ is consistent with being associated with the stellar mass identified with a 300 Myr-old stellar population independently indicated by a Balmer break in the spectral energy distribution. We conclude that the most of the dynamical mass is associated with the previously-identified mature stellar population that formed at $z\sim15$.
A detailed investigation of the scaling properties of the fully finite ${\cal O}(n)$ systems with long-range interaction, decaying algebraically with the interparticle distance $r$ like $r^{-d-\sigma}$, below their upper critical dimension is presented. The computation of the scaling functions is done to one loop order in the non-zero modes. The results are obtained in an expansion of powers of $\sqrt\epsilon$, where $\epsilon=2\sigma-d$ up to ${\cal O}(\epsilon^{3/2})$. The thermodynamic functions are found to be functions the scaling variable $z=RL^{2-\eta-\epsilon/2}U^{-1/2}$, where $R$ and $U$ are the coupling constants of the constructed effective theory, and $L$ is the linear size of the system. Some simple universal results are obtained.
We obtain a new estimate for Kloosterman sum with primes $p\leqslant X$ to composite modulo $q$, that is, for the exponential sum of the type \[ \sum\limits_{p\leqslant X,\;p\,\nmid q}\exp{\biggl(\frac{2\pi i}{q}\bigl(a\overline{p}+bp\bigr)\,\biggr)},\quad (ab,q)=1,\quad p\overline{p}\equiv 1\pmod{q}, \] which is non-trivial in the case when $q^{\,3/4+\varepsilon}\leqslant X\ll q^{\,3/2}$. We also apply this estimate to the proof of solvability of some congruences with inverse prime residues $\pmod{q}$.
Following our previous work, which related generic features in the sky-averaged (global) 21-cm signal to properties of the intergalactic medium, we now investigate the prospects for constraining a simple galaxy formation model with current and near-future experiments. Markov-Chain Monte Carlo fits to our synthetic dataset, which includes a realistic galactic foreground, a plausible model for the signal, and noise consistent with 100 hours of integration by an ideal instrument, suggest that a simple four-parameter model that links the production rate of Lyman-$\alpha$, Lyman-continuum, and X-ray photons to the growth rate of dark matter halos can be well-constrained (to $\sim 0.1$ dex in each dimension) so long as all three spectral features expected to occur between $40 \lesssim \nu / \mathrm{MHz} \lesssim 120$ are detected. Several important conclusions follow naturally from this basic numerical result, namely that measurements of the global 21-cm signal can in principle (i) identify the characteristic halo mass threshold for star formation at all redshifts $z \gtrsim 15$, (ii) extend $z \lesssim 4$ upper limits on the normalization of the X-ray luminosity star-formation rate ($L_X$-SFR) relation out to $z \sim 20$, and (iii) provide joint constraints on stellar spectra and the escape fraction of ionizing radiation at $z \sim 12$. Though our approach is general, the importance of a broad-band measurement renders our findings most relevant to the proposed Dark Ages Radio Explorer, which will have a clean view of the global 21-cm signal from $\sim 40-120$ MHz from its vantage point above the radio-quiet, ionosphere-free lunar far-side.
A recently developed continuous time solver based on an expansion in hybridization about an exactly solved local limit is reformulated in a manner appropriate for general classes of quantum impurity models including spin exchange and pair hopping terms. The utility of the approach is demonstrated via applications to the dynamical mean field theory of the Kondo lattice and two-orbital models. The algorithm can handle low temperatures and strong couplings without encountering a sign problem.
We have observed P-Cygni and asymmetric, blue-shifted absorption profiles in the He I 10830 lines of twelve R Coronae Borealis (RCB) stars over short (1 month) and long (3 year) timescales to look for variations linked to their dust-formation episodes. In almost all cases, the strengths and terminal velocities of the line vary significantly and are correlated with dust formation events. Strong absorption features with blue-shifted velocities ~400 km/s appear during declines in visible brightness and persist for about 100 days after recovery to maximum brightness. Small residual winds of somewhat lower velocity are present outside of the decline and recovery periods. The correlations support models in which recently formed dust near the star is propelled outward at high speed by radiation pressure and drags the gas along with it.
A locking protocol between two parties is as follows: Alice gives an encrypted classical message to Bob which she does not want Bob to be able to read until she gives him the key. If Alice is using classical resources, and she wants to approach unconditional security, then the key and the message must have comparable sizes. But if Alice prepares a quantum state, the size of the key can be comparatively negligible. This effect is called quantum locking. Entanglement does not play a role in this quantum advantage. We show that, in this scenario, the quantum discord quantifies the advantage of the quantum protocol over the corresponding classical one for any classical-quantum state.
We consider the end state of collapsing null radiation with a string fluid. It is shown that, if diffusive transport is assumed for the string, that a naked singularity can form (at least locally). The model has the advantage of not being asymptotically flat. We also analyse the case of a radiation-string two-fluid and show that a locally naked singularity can result in the collapse of such matter. We contrast this model with that of strange quark matter.
Deep Metric Learning (DML) proposes to learn metric spaces which encode semantic similarities as embedding space distances. These spaces should be transferable to classes beyond those seen during training. Commonly, DML methods task networks to solve contrastive ranking tasks defined over binary class assignments. However, such approaches ignore higher-level semantic relations between the actual classes. This causes learned embedding spaces to encode incomplete semantic context and misrepresent the semantic relation between classes, impacting the generalizability of the learned metric space. To tackle this issue, we propose a language guidance objective for visual similarity learning. Leveraging language embeddings of expert- and pseudo-classnames, we contextualize and realign visual representation spaces corresponding to meaningful language semantics for better semantic consistency. Extensive experiments and ablations provide a strong motivation for our proposed approach and show language guidance offering significant, model-agnostic improvements for DML, achieving competitive and state-of-the-art results on all benchmarks. Code available at https://github.com/ExplainableML/LanguageGuidance_for_DML.
We present a new ${\it{gating}}$ method to remove non-Gaussian noise transients in gravitational wave data. The method does not rely on any a-priori knowledge on the amplitude or duration of the transient events. In light of the character of the newly released LIGO O3a data, glitch-identification is particularly relevant for searches using this data. Our method preserves more data than previously achieved, while obtaining the same, if not higher, noise reduction. We achieve a $\approx$ 2-fold reduction in zeroed-out data with respect to the gates released by LIGO on the O3a data. We describe the method and characterise its performance. While developed in the context of searches for continuous signals, this method can be used to prepare gravitational wave data for any search. As the cadence of compact binary inspiral detections increases and the lower noise level of the instruments unveils new glitches, excising disturbances effectively, precisely, and in a timely manner, becomes more important. Our method does this. We release the source code associated with this new technique and the gates for the newly released O3 data.
We give a unified formulation of a mass for arbitrary abelian varieties with PEL-structures and show that it equals a weighted class number of a reductive $\Q$-group $G$ relative to an open compact subgroup $U$ of $G(\A_f)$, or simply called an {\it arithmetic mass}. We classify the special objects for which our formulation remains valid over algebraic closed fields. As a result, we show that the set of basic points in a mod $p$ moduli space of PEL-type with a local condition (and a mild condition subject to the Hasse principle) can be expressed as a double coset space and its mass equals an arithmetic mass. The moduli space does not need to have good reduction at $p$. This generalizes a well-known result for superspecial abelian varieties.
A quasistatic model due to Ericksen and Leslie describing incompressible liquid crystals is studied for a general class of free energies. Global existence of weak solutions is proven via a Galerkin approximation with eigenfunctions of a strongly elliptic operator. A novelty is that the principal part of the differential operator appearing in the director equation can be nonlinear.
We study a single server queue under a processor-sharing type of scheduling policy, where the weights for determining the sharing are given by functions of each job's remaining service(processing) amount, and obtain a fluid limit for the scaled measure-valued system descriptors.
We present new data on Cherenkov light observations obtained during the period 1994-2009, after a modernization of the Yakutsk EAS array. A complex analysis of $\xmax$ and its fluctuations $\sigma(\xmax)$ was performed over a wide energy range. With the new data, according to QGSJet II model, an estimation was made of the cosmic ray mass composition for $\E \sim 10^{17} - 3 \times 10^{19}$ eV. The result points towards a mixed composition with a large portion of heavy nuclei at $\E \sim 10^{17}$ eV and the dominance of light nuclei at $\E \sim 10^{19}$ eV. The analysis of $\sigma(\xmax)$ energy dependence for the same energies qualitatively confirms this result. The shape of the $\xmax$ distribution at fixed energy $10^{18}$ eV is analysed to make more precise conclusions on cosmic ray mass composition.
A single four-level atom interacting with two-mode cavities is investigated. Under large detuning condition, we obtain the effective Hamiltonian which is unitary squeezing operator of two-mode fields. Employing the input-output theory, we find that the entanglement and squeezing of the output fields can be achieved. By analyzing the squeezing spectrum, we show that asymmetric detuning and asymmetric atomic initial state split the squeezing spectrum from one valley into two minimum values, and appropriate leakage of the cavity is needed for obtaining output entangled fields.
The dynamics of a Markov process are often specified by its infinitesimal generator or, equivalently, its symbol. This paper contains examples of analytic symbols which do not determine the law of the corresponding Markov process uniquely. These examples also show that the law of a polynomial process is not necessarily determined by its generator. On the other hand, we show that a combination of smoothness of the symbol and ellipticity warrants uniqueness in law. The proof of this result is based on proving stability of univariate marginals relative to some properly chosen distance.