ShantanuT01/DACTYL-Pretraining huggingface dataset:
Rotation equivariance has recently become a strongly desired property in the 3D deep learning community. Yet most existing methods focus on equivariance regarding a global input rotation while ignoring the fact that rotation symmetry has its own spatial support. Specifically, we consider the object detection problem in 3D scenes, where an object bounding box should be equivariant regarding the object pose, independent of the scene motion. This suggests a new desired property we call object-level rotation equivariance. To incorporate object-level rotation equivariance into 3D object detectors, we need a mechanism to extract equivariant features with local object-level spatial support while being able to model cross-object context information. To this end, we propose Equivariant Object detection Network (EON) with a rotation equivariance suspension design to achieve object-level equivariance. EON can be applied to modern point cloud object detectors, such as VoteNet and PointRCNN, enabling them to exploit object rotation symmetry in scene-scale inputs. Our experiments on both indoor scene and autonomous driving datasets show that significant improvements are obtained by plugging our EON design into existing state-of-the-art 3D object detectors.
The $\Lambda N$ and $\Sigma N$ interactions are considered at next-to-leading order in SU(3) chiral effective field theory. Different options for the low-energy constants that determine the strength of the contact interactions are explored. Two variants are analysed in detail which yield equivalent results for $\Lambda N$ and $\Sigma N$ scattering observables but differ in the strength of the $\Lambda N \to \Sigma N$ transition potential. The influence of this difference on predictions for light hypernuclei and on the properties of the $\Lambda$ and $\Sigma$ hyperons in nuclear matter is investigated and discussed. The effect of the variation in the potential strength of the $\Lambda N$-$\Sigma N$ coupling (also called $\Lambda -\Sigma$ conversion) is found to be moderate for the considered $^3_\Lambda \rm H$ and $^4_\Lambda \rm He$ hypernuclei but sizable in case of the matter properties. Further, the size of three-body forces and their relation to different approaches to hypernuclear interactions is discussed.
Two-dimensional (2D) massive Dirac electrons possess a finite Berry curvature, with Chern number $\pm 1/2$, that entails both a quantized dc Hall response and a subgap full-quarter Kerr rotation. The observation of these effects in 2D massive Dirac materials such as gapped graphene, hexagonal boron nitride or transition metal dichalcogenides (TMDs) is obscured by the fact that Dirac cones come in pairs with opposite sign Berry curvatures, leading to a vanishing Chern number. Here, we show that the presence of spin-orbit interactions, combined with an exchange spin splitting induced either by diluted magnetic impurities or by proximity to a ferromagnetic insulator, gives origin to a net magneto-optical Kerr effect in such systems. We focus on the case of TMD monolayers and study the dependence of Kerr rotation on frequency and exchange spin splitting. The role of the substrate is included in the theory and found to critically affect the results. Our calculations indicate that state-of-the-art magneto-optical Kerr spectroscopy can detect a single magnetic impurity in diluted magnetic TMDs.
We construct a manifestly N=3 supersymmetric low-energy effective action of N=3 super Yang-Mills theory. The effective action is written in the N=3 harmonic superspace and respects the full N=3 superconformal symmetry. On mass shell this action is responsible for the four-derivative terms in the N=4 SYM effective action, such as F^4/X^4 and its supersymmetric completions, while off shell it involves also higher-derivative terms. For constant Maxwell and scalar fields its bosonic part coincides, up to the F^6/X^8 order, with the bosonic part of the D3 brane action in the AdS_5 x S^5 background. We also argue that in the sector of scalar fields it involves the correctly normalized Wess-Zumino term with the implicit SU(3) symmetry.
In this paper, we investigate the problem of text-to-pedestrian synthesis, which has many potential applications in art, design, and video surveillance. Existing methods for text-to-bird/flower synthesis are still far from solving this fine-grained image generation problem, due to the complex structure and heterogeneous appearance that the pedestrians naturally take on. To this end, we propose the Multi-Grained Discrimination enhanced Generative Adversarial Network, that capitalizes a human-part-based Discriminator (HPD) and a self-cross-attended (SCA) global Discriminator in order to capture the coherence of the complex body structure. A fined-grained word-level attention mechanism is employed in the HPD module to enforce diversified appearance and vivid details. In addition, two pedestrian generation metrics, named Pose Score and Pose Variance, are devised to evaluate the generation quality and diversity, respectively. We conduct extensive experiments and ablation studies on the caption-annotated pedestrian dataset, CUHK Person Description Dataset. The substantial improvement over the various metrics demonstrates the efficacy of MGD-GAN on the text-to-pedestrian synthesis scenario.
The Cox ring of a so-called Mori Dream Space (MDS) is finitely generated and it is graded over the divisor class group. Hence the spectrum of the Cox ring comes with an action of an algebraic torus whose GIT quotient is the variety in question. We present the associated description of this Cox ring as a polyhedral divisor. Via the shape of its polyhedral coefficients, it connects the equivariant structure of the Cox ring with the world of stable loci and stable multiplicities of linear systems.
Based on a kinetic description of J/psi dissociation and production in an expanding quark-gluon plasma that is described by a 2+1 dimensional ideal hydrodynamics, we have studied the hot medium effects on J/psi production in p+Pb collisions at sqrt{s_{NN}}=5.02 TeV. Including also the cold nuclear matter effects, we are able to reproduce recent experimental results on the nuclear modification factor R_{pPb}(J/psi) measured by the ALICE Collaboration. We have also made predictions for the R_{pPb} of J/psi and the double ratio R_{pPb}^{pro}(psi')/R_{pPb}^{pro}(J/psi) of prompt quarkonia produced in the most central 10% p+Pb collisions. We find that different from the cold nuclear matter effects, the R_{pPb}(J/psi) is slightly smaller than that in the minimum bias collisions, and the double ratio is significantly less than one at backward rapidity.
Part-based models with restrictive tree-structured interactions for the Human Pose Estimation problem, leaves many part interactions unhandled. Two of the most common and strong manifestations of such unhandled interactions are self-occlusion among the parts and the confusion in the localization of the non-adjacent symmetric parts. By handling the self-occlusion in a data efficient manner, we improve the performance of the basic Mixture of Parts model by a large margin, especially on uncommon poses. Through addressing the confusion in the symmetric limb localization using a combination of two complementing trees, we improve the performance on all the parts by atmost doubling the running time. Finally, we show that the combination of the two solutions improves the results. We report results that are equivalent to the state-of-the-art on two standard datasets. Because of maintaining the tree-structured interactions and only part-level modeling of the base Mixture of Parts model, this is achieved in time that is much less than the best performing part-based model.
We consider N=1 supersymmetric gauge theories in which the couplings are allowed to be space-time dependent functions. Both the gauge and the superpotential couplings become chiral superfields. As has recently been shown, a new topological anomaly appears in models with space-time dependent gauge coupling. Here we show how this anomaly may be used to derive the NSVZ beta function in a particular, well-determined renormalisation scheme, both without and with chiral matter. Moreover we extend the topological anomaly analysis to theories coupled to a classical curved superspace background, and use it to derive an all-order expression for the central charge c, the coefficient of the Weyl tensor squared contribution to the conformal anomaly. We also comment on the implications of our results for the central charge a expected to be of relevance for a four-dimensional C-theorem.
The Rashba Hamiltonian describes the splitting of the conduction band as a result of spin-orbit coupling in the presence of an asymmetric confinement potential and is commonly used to model the electronic structure of confined narrow-gap semiconductors. Due to the mixing of spin states some care has to be exercised in the calculation of transport properties. We derive the diffusive conductance tensor for a disordered two-dimensional electron gas with spin-orbit interaction and show that the applied bias induces a spin accumulation, but that the electric current is not spin-polarized.
Let $J$ be the Jacobian of a smooth projective curve. We define a natural action of the Lie algebra of polynomial Hamiltonian vector fields on the plane, vanishing at the origin, on the Chow group of $J$ with rational coefficients. Using this action we obtain some relations between tautological cycles on $J$.
Supermassive black holes can launch powerful jets which can be some of the most luminous multi-wavelength sources; decades after their discovery their physics and energetics are still poorly understood. The past decade has seen a dramatic improvement in the quality of available data, but despite this improvement the semi-analytical modelling of jets has advanced slowly: simple one-zone models are still the most commonly employed method of interpreting data, in particular for AGN jets. These models can roughly constrain the properties of jets but they cannot unambiguously couple their emission to the launching regions and internal dynamics, which can be probed with simulations. However, simulations are not easily comparable to observations because they cannot yet self-consistently predict spectra. We present an advanced semi-analytical model which accounts for the dynamics of the whole jet, starting from a simplified parametrization of Relativistic Magnetohydrodynamics in which the magnetic flux is converted into bulk kinetic energy. To benchmark the model we fit six quasisimultaneous, multi-wavelength spectral energy distributions of the BL Lac PKS 2155-304 obtained by the TANAMI program, and we address the degeneracies inherent to such a complex model by employing a state-of-the-art exploration of parameter space, which so far has been mostly neglected in the study of AGN jets. We find that this new approach is much more effective than a single-epoch fit in providing meaningful constraints on model parameters.
Monte Carlo simulation has been performed in one-dimensional Lebwohl-Lasher model and two dimensional XY-model using the Wang-Landau and the Wang-Landau-Transition-Matrix Monte Carlo methods. Random walk has been performed in the two-dimensional space comprising of energy-order parameter and energy-correlation function and the joint density of states (JDOS) were obtained. From the JDOS the order parameter, susceptibility and correlation function are calculated. Agreement between the results obtained from the two algorithms is very good.
The calculations of electronic transport coefficients and optical properties require a very dense interpolation of the electronic band structure in reciprocal space that is computationally expensive and may have issues with band crossing and degeneracies. Capitalizing on a recently developed pseudo-atomic orbital projection technique, we exploit the exact tight-binding representation of the first principles electronic structure for the purposes of (1) providing an efficient strategy to explore the full band structure $E_n({\bf k})$, (2) computing the momentum operator differentiating directly the Hamiltonian, and (3) calculating the imaginary part of the dielectric function. This enables us to determine the Boltzmann transport coefficients and the optical properties within the independent particle approximation. In addition, the local nature of the tight-binding representation facilitates the calculation of the ballistic transport within the Landauer theory for systems with hundreds of atoms. In order to validate our approach we study the multi-valley band structure of CoSb$_3$ and a large core-shell nanowire using the ACBN0 functional. In CoSb$_3$ we point the many band minima contributing to the electronic transport that enhance the thermoelectric properties; for the core-shell nanowire we identify possible mechanisms for photo-current generation and justify the presence of protected transport channels in the wire.
Weak lensing convergence peaks are a promising tool to probe nonlinear structure evolution at late times, providing additional cosmological information beyond second-order statistics. Previous theoretical and observational studies have shown that the cosmological constraints on $\Omega_m$ and $\sigma_8$ are improved by a factor of up to ~ 2 when peak counts and second-order statistics are combined, compared to using the latter alone. We study the origin of lensing peaks using observational data from the 154 deg$^2$ Canada-France-Hawaii Telescope Lensing Survey. We found that while high peaks (with height $\kappa$ >3.5 $\sigma_\kappa$, where $\sigma_\kappa$ is the r.m.s. of the convergence $\kappa$) are typically due to one single massive halo of ~$10^{15}M_\odot$, low peaks ($\kappa$ <~ $\sigma_\kappa$) are associated with constellations of 2-8 smaller halos (<~$10^{13}M_\odot$). In addition, halos responsible for forming low peaks are found to be significantly offset from the line-of-sight towards the peak center (impact parameter >~ their virial radii), compared with ~0.25 virial radii for halos linked with high peaks, hinting that low peaks are more immune to baryonic processes whose impact is confined to the inner regions of the dark matter halos. Our findings are in good agreement with results from the simulation work by Yang el al. (2011).
We compare recently proposed methods to compute the electronic state energies of the water molecule on a quantum computer. The methods include the phase estimation algorithm based on Trotter decomposition, the phase estimation algorithm based on the direct implementation of the Hamiltonian, direct measurement based on the implementation of the Hamiltonian and a specific variational quantum eigensolver, Pairwise VQE. After deriving the Hamiltonian using STO-3G basis, we first explain how each method works and then compare the simulation results in terms of gate complexity and the number of measurements for the ground state of the water molecule with different O-H bond lengths. Moreover, we present the analytical analyses of the error and the gate-complexity for each method. While the required number of qubits for each method is almost the same, the number of gates and the error vary a lot. In conclusion, among methods based on the phase estimation algorithm, the second order direct method provides the most efficient circuit implementations in terms of the gate complexity. With large scale quantum computation, the second order direct method seems to be better for large molecule systems. Moreover, Pairwise VQE serves the most practical method for near-term applications on the current available quantum computers. Finally the possibility of extending the calculation to excited states and resonances is discussed.
We present an improved version of Diaconis' upper bound lemma, which is used to compute the limiting value of the distance to stationarity. We then apply it to random transpositions studied by Diaconis and Shahshahani.
A Toffoli gate ($C^{n}$-NOT gate) is regarded as an important unitary gate in quantum computation, and is simulated by a quantum circuit composed of $C^{2}$-NOT gates. This paper presents a quantum circuit with a new configuration of $C^{2}$-NOT gates simulating a $C^{2m+1}$-NOT operation under the condition $m=2^{n}$ ($n=1,2,...$). The circuit is composed of units called multi-qubits gates (MQGs), each of which performs $m$ $C^{2}$-NOT operations simultaneously on $3m$ qubits. Simultaneous operations eliminate the need to manipulate qubits individually, as required in conventional quantum circuits. The proposed circuit thus represents a more realistic mode of operation for practical computing systems. A nuclear magnetic resonance implementation of the circuit is presented as a demonstration of the feasibility of MQG operations for practical systems.
Numerical evidence for a cosmological version of the Bartnik-McKinnon family of particle-like solutions of the Einstein-Yang-Mills system is presented. Our solutions are also static, but space has the topology of a three-sphere. By adjusting the cosmological constant we found numerically a spherically symmetric solution which can be regarded as an excitation of the unique SO(4)-invariant solution. We expect that for each node number there exists such a solution without a cosmological horizon.
Let Gamma be a Q-polynomial distance-regular graph with vertex set X, diameter D geq 3 and adjacency matrix A. Fix x in X and let A*=A*(x) be the corresponding dual adjacency matrix. Recall that the Terwilliger algebra T=T(x) is the subalgebra of Mat_X(C) generated by A and A*. Let W denote a thin irreducible T-module. It is known that the action of A and A* on W induces a linear algebraic object known as a Leonard pair. Over the past decade, many results have been obtained concerning Leonard pairs. In this paper, these results will be applied to obtain a detailed description of W. In particular, we give a description of W in terms of its intersection numbers, dual intersection numbers and parameter array. Finally, we apply our results to the case in which Gamma has q-Racah type or classical parameters.
Photon number resolving detectors are the ultimate measurement of quantum optics, which is the reason why developing the technology is getting significant attention in recent years. With this arises the question of how to evaluate the performance of the detectors. We suggest that performance of a photon number detector can be evaluated by comparing it to a multiplex of on-off detectors in a practical scenario: conditional preparation of a photon number state. Here, both the quality of the prepared state and the probability of the preparation are limited by the number of on-off detectors in the multiplex, which allows us to set benchmarks that can be achieved or surpassed by the photon number resolving detectors.
We discuss the possibility of studying diffuse baryon distributions with kinematic Sunyaev-Zel'dovich (kSZ) effect by correlating cosmic microwave background (CMB) temperature fluctuations with density fluctuations from 21\,cm intensity mapping (IM). The biggest challenge for the cross-correlation is the loss of large-scale information in IM, due to foregrounds and the zero spacing problem of interferometers. We apply the tidal reconstruction algorithm to restore the lost large-scale modes, which increases the correlation by more than a factor of three. With the predicted foreground level, we expect a $\sim20\,\sigma$ detection of kSZ signal for $0.8\lesssim z\lesssim2.5$ with CHIME and Planck, and a $\sim40\, \sigma$ detection with HIRAX and Planck. The significance can be greatly increased with next-generation facilities of higher spatial resolutions.
We present a comparison between the spectroscopic catalog of the HDF recently published by Cohen et al and the redshifts measured by our group for those objects using photometric techniques. We perform this comparison in order to characterize the errors associated to the photometric redshift technique. The spectroscopic sample includes over 140 objects in the HDF proper, representing the deepest, cleanest, most complete spectroscopic catalog ever compiled. We study each object for which our redshift and the one measured by Cohen et al disagree. In most cases the photometric evidence is strong enough to call for a careful review of the spectroscopic values, as they seem to be in error. It is possible to characterize the systematic errors associated to our technique, which when combined with the photometric errors allow us to obtain complete information on the redshift of each galaxy and its associated confidence interval, regardless of apparent magnitude. One of the main conclusions of this study is that, to date, all the redshifts from our published catalog that have been checked have been shown to be correct (within the stated confidence limits). This implies that our galaxy template set is a fair representation of the galaxy population at all redshifts (0<z<6) and magnitudes (R<24) explored to date. On the other hand, spectroscopy of faint sources is subject to unknown and uncharacterized systematic errors, that will in turn be transmitted to any photometric redshift technique which uses spectroscopic samples as calibration. Our analysis proves that photometric redshift techniques can and must be used to extend the range of applicability of the spectroscopic redshift measurements. (Abridged)
In this paper, we discuss the effects of nonlinear electrodynamics (NED) on non-rotating black holes, parametrized by the field coupling parameter $\beta$ and magnetic charge parameter $P$ in detail. Particularly, we survey physical properties of the magnetically charged black hole, thermodynamic properties, observational appearance, quasinormal modes and absorption cross sections. We then show that the black hole gets colder with increasing charge. Investigating the heat capacity, we see that the black hole is thermally stable, which is amplified by introduction of a generalized uncertainty principle (GUP) with a quantum gravity parameter $\lambda$. Then we compute the deflection angle at the weak field limit, by the Gauss-Bonnet theorem and the geodesic equation, showing that the magnetic charge has a contribution at the first order. By ray-tracing we simulate the observational appearance of a NED black hole with thin disk and spherical accretion. We find that the parameter $P$ has a very strong effect on the shadow radius. We consider quasinormal modes under massless scalar perturbations of the black hole and the greybody factor. We find that the charge introduces a slight difference in the fundamental frequency and that the greybody factor of the NED black hole is strongly steepened by the introduction of increasing charge. To present observational constrains, we show that the magnetic charge of the M87* black hole is between $0\leq P\leq0.024$ in units of M, in agreement with the idea that real astrophysical black holes are mostly neutral. We also find that LIGO/VIRGO and LISA could detect NED black hole perturbations from BHs with masses between $5M_\odot$ and $8.0\cdot 10^8\,M_\odot$. We finally show that for black holes with masses detected with LIGO so far, charged NED black holes would deviate from Schwarzschild by $5\sim 10$ Hz in their fundamental frequencies.
Explicit field theory computations are carried out of the joint probabilities associated with spin correlations of $\mu^{-}\mu^{+}$ produced in $e^{-}e^{+}$ collision in the standard electroweak model to the leading order. The derived expressions are found to depend not only on the speed of the $e^{-}e^{+}$ pair but also on the underlying couplings. These expressions are unlike the ones obtained from simply combining the spins of the relevant particles which are of kinematical nature. It is remarkable that these explicit results obtained from quantum field theory show a clear violation of Bell's inequality.