ShantanuT01/DACTYL-Pretraining huggingface dataset:
We present phase-resolved spectroscopy of two new short period low accretion rate magnetic binaries, SDSSJ125044.42+154957.3 (Porb = 86 min) and SDSSJ151415.65+074446.5 (Porb = 89 min). Both systems were previously identified as magnetic white dwarfs from the Zeeman splitting of the Balmer absorption lines in their optical spectra. Their spectral energy distributions exhibit a large near-infrared excess, which we interpret as a combination of cyclotron emission and possibly a late type companion star. No absorption features from the companion are seen in our optical spectra. We derive the orbital periods from a narrow, variable H_alpha emission line which we show to originate on the companion star. The high radial velocity amplitude measured in both systems suggests a high orbital inclination, but we find no evidence for eclipses in our data. The two new systems resemble the polar EF Eri in its prolonged low state and also SDSSJ121209.31+013627.7, a known magnetic white dwarf plus possible brown dwarf binary, which was also recovered by our method.
We calculate the renormalized parameters for the quasiparticles and their interactions for the Hubbard model in the paramagnetic phase as deduced from the low energy Fermi liquid fixed point using the results of a numerical renormalization group calculation (NRG) and dynamical mean-field theory (DMFT). Even in the low density limit there is significant renormalization of the local quasiparticle interaction $\tilde U$, in agreement with estimates based on the two-particle scattering theory of Kanamori (1963). On the approach to the Mott transition we find a finite ratio for $\tilde U/\tilde D$, where $2\tilde D$ is the renormalized bandwidth, which is independent of whether the transition is approached by increasing the on-site interaction $U$ or on increasing the density to half-filling.The leading $\omega^2$ term in the self-energy and the local dynamical spin and charge susceptibilities are calculated within the renormalized perturbation theory (RPT) and compared with the results calculated directly from the NRG-DMFT. The dynamic ${\bf q},\omega$ spin susceptibility $\chi({\bf q},\omega)$ is also estimated from repeated quasiparticle scattering with a local renormalized scattering vertex.
Do spatial distributions of dust grains in galaxies have typical forms, as do spatial distributions of stars? We investigate whether or not the distributions resemble uniform foreground screens, as commonly assumed by the high-redshift galaxy community. We use rest-frame infrared, ultraviolet, and H$\alpha$ line luminosities of dust-poor and dusty galaxies at z ~ 0 and z ~ 1 to compare measured H$\alpha$ escape fractions with those predicted by the Calzetti attenuation formula. The predictions, based on UV escape fractions, overestimate the measured H$\alpha$ escape fractions for all samples. The interpretation of this result for dust-poor z ~ 0 galaxies is that regions with ionizing stars have more dust than regions with nonionizing UV-emitting stars. Dust distributions for these galaxies are nonuniform. The interpretation of the overestimates for dusty galaxies at both redshifts is less clear. If the attenuation formula is inapplicable to these galaxies, perhaps the disagreements are unphysical; perhaps dust distributions in these galaxies are uniform. If the attenuation formula does apply, then dusty galaxies have nonuniform dust distributions; the distributions are more uniform than they are in dust-poor galaxies. A broad range of H$\alpha$ escape fractions at a given UV escape fraction for z ~ 1 dusty galaxies, if real, indicates diverse dust morphologies and the implausibility of the screen assumption.
A scenario is presented for the formation of first life in the universe based on hydro-gravitational-dynamics (HGD) cosmology. From HGD, the dark matter of galaxies is H-He gas dominated planets (primordial-fog-particle PFPs) in million solar mass clumps (protoglobularstarcluster PGCs), which formed at the plasma to gas transition temperature 3000 K. Stars result from mergers of the hot-gas-planets. Over-accretion causes stars to explode as supernovae that scatter life-chemicals (C, N, O, P, S, Ca, Fe etc.) to other planets in PGC clumps and beyond. These chemicals were first collected gravitationally by merging PFPs to form H-saturated, high-pressure, dense oceans of critical-temperature 647 K water over iron-nickel cores at ~ 2 Myr. Stardust fertilizes the formation of first life in a cosmic hot-ocean soup kitchen comprised of all planets and their moons in meteoric communication, > 10^100 kg in total. Ocean freezing slows this biological big bang at ~ 8 Myr. HGD cosmology confirms that the evolving seeds of life are scattered on intergalactic scales by Hoyle-Wickramasinghe cometary panspermia. Thus, life flourishes on planets like Earth that would otherwise be sterile.
As previously discussed in (D. Sudarsky, Int.J.Mod.Phys.D20:509-552, (2011); [arXiv:0906.0315]), the inflationary account for the emergence of the seeds of cosmic structure falls short of actually explaining the generation of primordial anisotropies and inhomogeneities. This description starts from a symmetric background, and invokes symmetric dynamics, so it cannot explain asymmetries. To generate asymmetries, we present an application of the Continuous Spontaneous Localization (CSL) model of wave function collapse (P. Pearle, Phys. Rev. A 39, 2277, (1989); G. C. Ghirardi, P. Pearle and A. Rimini, Phys. Rev. A42, 78 (1990)) in the context of inflation. This modification of quantum dynamics introduces a stochastic non-unitary component to the evolution of the inflaton field perturbations. This leads to passage from a homogeneous and isotropic stage to another, where the quantum uncertainties in the initial state of inflation transmute into the primordial inhomogeneities and anisotropies. We examine requirements for, and show how to achieve, compatibility with the precise observations of the cosmic microwave background (CMB) radiation.
We consider the Cauchy-problem for a parabolic equation of the following type:   \begin{equation*}   \frac{\partial u}{\partial t}= \Delta u+ f(u,|x|),   \end{equation*} where $f=f(u,|x|)$ is supercritical. We supply this equation by the initial condition $u(x,0)=\phi$, and we allow $\phi$ to be either bounded or unbounded in the origin but smaller than stationary singular solutions. We discuss local existence and long time behaviour for the solutions $u(t,x;\phi)$ for a wide class of non-homogeneous non-linearities $f$. We show that in the supercritical case, Ground States with slow decay lie on the threshold between blowing up initial data and the basin of attraction of the null solution. Our results extend previous ones allowing Matukuma-type potential and more generic dependence on $u$.   Then, we further explore such a threshold in the subcritical case too. We find two families of initial data $\zeta(x)$ and $\psi(x)$ which are respectively above and below the threshold, and have arbitrarily small distance in $L^{\infty}$ norm, whose existence is new even for $f(u,r)=u^{q-1}$. Quite surprisingly both $\zeta(x)$ and $\psi(x)$ have fast decay (i.e. $\sim |x|^{2-n}$), while the expected critical asymptotic behavior is slow decay (i.e. $\sim |x|^{2/q-2}$).
Let $X$ be a compact connected Riemann surface of genus at least two. The Abel-Jacobi map $\varphi: {\rm Sym}^d(X) \rightarrow {\rm Pic}^d(X)$ is an embedding if $d$ is less than the gonality of $X$. We investigate the curvature of the pull-back, by $\varphi$, of the flat metric on ${\rm Pic}^d(X)$. In particular, we show that when $d=1$, the curvature is strictly negative everywhere if $X$ is not hyperelliptic, and when $X$ is hyperelliptic, the curvature is nonpositive with vanishing exactly on the points of $X$ fixed by the hyperelliptic involution.
Most iris recognition pipelines involve three stages: segmenting into iris/non-iris pixels, normalization the iris region to a fixed area, and extracting relevant features for comparison. Given recent advances in deep learning it is prudent to ask which stages are required for accurate iris recognition. Lojez et al. (IWBF 2019) recently concluded that the segmentation stage is still crucial for good accuracy.We ask if normalization is beneficial? Towards answering this question, we develop a new iris recognition system called ThirdEye based on triplet convolutional neural networks (Schroff et al., ICCV 2015). ThirdEye directly uses segmented images without normalization. We observe equal error rates of 1.32%, 9.20%, and 0.59% on the ND-0405, UbirisV2, and IITD datasets respectively. For IITD, the most constrained dataset, this improves on the best prior work. However, for ND-0405 and UbirisV2,our equal error rate is slightly worse than prior systems. Our concluding hypothesis is that normalization is more important for less constrained environments.
We obtain a simple relationship between the change in the Brown-York energy inside of a closed two-surface just outside of a horizon of spacetime, and the change in the area of that two-surface.
The magnetic phase diagrams of RMnO3 (R = Er, Yb, Tm, Ho) are investigated up to 14 Tesla via magnetic and dielectric measurements. The stability range of the AFM order below the Neel temperature of the studied RMnO3 extends to far higher magnetic fields than previously assumed. Magnetic irreversibility indicating the presence of a spontaneous magnetic moment is found near 50 K for R=Er, Yb, and Tm. At very low temperatures and low magnetic fields the phase boundary defined by the ordering of the rare earth moments is resolved. The sizable dielectric anomalies observed along all phase boundaries are evidence for strong spin-lattice coupling in the hexagonal RMnO3. In HoMnO3 the strong magnetoelastic distortions are investigated in more detail via magnetostriction experiments up to 14 Tesla. The results are discussed based on existing data on magnetic symmetries and the interactions between the Mn-spins, the rare earth moments, and the lattice.
We give a method for producing explicit bounds on $g(p)$, the least primitive root modulo $p$. Using our method we show that $g(p)<2r\,2^{r\omega(p-1)}\,p^{\frac{1}{4}+\frac{1}{4r}}$ for $p>10^{56}$ where $r\geq 2$ is an integer parameter. This result beats existing bounds that rely on explicit versions of the Burgess inequality. Our main result allows one to derive bounds of differing shapes for various ranges of $p$. For example, our method also allows us to show that $g(p)<p^{5/8}$ for all $p\geq 10^{22}$ and $g(p)<p^{1/2}$ for $p\geq 10^{56}$.
It is becoming increasingly important to understand the uncertainties of nuclear mass model calculations and their limitations when extrapolating to driplines. In this paper we evaluate the parameter uncertainties the Duflo-Zuker (DZ) shell model mass formulae by fitting to the latest experimental mass compilation AME2012 and analyze the propagation of the uncertainties in binding energy calculations when extrapolated to driplines. The parameter uncertainties and uncertain propagations are evaluated with the help of the covariance matrix thus derived. Large deviations from the extrapolations of AME2012 are seen in superheavy nuclei. A simplified version of the DZ model (DZ19) with much smaller uncertainties than that of DZ33 is proposed. Calculations are compared with results from other mass formulae. Systematics on the uncertainty propagation as well as the positions of the driplines are also presented. The DZ mass formulae are shown to be well defined with good extrapolation properties and rather small uncertainties, even though some of the parameters of the full DZ33 model cannot be fully determined by fitting to available experimental data.
In this paper we show the existence of global minimizers for the geometrically exact, non-linear equations of elastic plates, in the framework of the general 6-parametric shell theory. A characteristic feature of this model for shells is the appearance of two independent kinematic fields: the translation vector field and the rotation tensor field (representing in total 6 independent scalar kinematic variables). For isotropic plates, we prove the existence theorem by applying the direct methods of the calculus of variations. Then, we generalize our existence result to the case of anisotropic plates. We also present a detailed comparison with a previously established Cosserat plate model.
Given a star-shaped domain $K\subseteq \mathbb R^d$, $n$ vectors $v_1,\dots,v_n \in \mathbb R^d$, a number $R>0$, and i.i.d. random variables $\eta_1,\dots,\eta_n$, we study the geometric and arithmetic structure of the set of vectors $V = \{v_1,\dots,v_n\}$ under the assumption that the small ball probability \[\sup_{x\in \mathbb R^d}~\mathbb P\Bigg(\sum_{j=1}^n\eta_jv_j\in x+RK\Bigg)\] does not decay too fast as $n\to \infty$. This generalises the case where $K$ is the Euclidean ball, which was previously studied by Nguyen-Vu and Tao-Vu.
In this paper, we prove a general theorem concerning the analyticity of the closure of a subspace defined by a family of variations of mixed Hodge structures, which includes the analyticity of the zero loci of degenerating normal functions. For the proof, we use a moduli of the valuative version of log mixed Hodge structures.
Let $p>3$ be a prime, and let $q_p(2)=(2^{p-1}-1)/p$ be the Fermat quotient of $p$ to base 2. Recently, Z. H. Sun proved that \sum_{k=1}^{p-1}\frac{1}{k\cdot 2^k}\equiv q_p(2)-\frac{p}{2}q_p(2)^2 \pmod{p^2} which is a generalization of a congruence due to W. Kohnen. In this note we give an elementary proof of the above congruence which is based on several combinatorial identities and congruences involving the Fermat quotient $q_p(2)$, harmonic or alternating harmonic sums.
Based on the fact that the entanglement can not be created locally, we proposed a quantum bit commitment protocol, in which entangled states and quantum algorithms is used. The bit is not encoded with the form of the quantum states, and delaying the measurement is required. Therefore the protocol will not be denied by the Mayers-Lo-Chau no-go theorem, and unconditional security is achieved.
The statistics of the heat exchanged between two quantum XX spin chains prepared at different temperatures is studied within the assumption of weak coupling. This provides simple formulas for the average heat and its corresponding characteristic function, from which the probability distribu- tion may be computed numerically. These formulas are valid for arbitrary sizes and therefore allow us to analyze the role of the thermodynamic limit in this non-equilibrium setting. It is found that all thermodynamic quantities are extremely sensitive to the quantum phase transition of the XX chain.
Defects intentionally introduced into magnetic materials often have a profound effect on the physical properties. Specifically tailored neutron spectroscopic experiments can provide detailed information on both the local exchange interactions and the local distances between the magnetic atoms around the defects. This is demonstrated for manganese dimer excitations observed for the magnetically diluted three-, two- and one-dimensional compounds KMnxZn1-xF3, K2MnxZn1-xF4 and CsMnxMg1-xBr3, respectively, with x=0.10. The resulting local exchange interactions deviate up to 10% from the average, and the local Mn-Mn distances are found to vary stepwise with increasing internal chemical pressure due to the Mn/Zn or Mn/Mg substitution. Our analysis qualitatively supports the theoretically predicted decay of atomic displacements according to 1/r**2, 1/r and constant (for three-, two- and one-dimensional compounds, respectively) where r denotes the distance of the displaced atoms from the defect.
We study the concepts of compatibility and separability and their implications for quantum and classical systems. These concepts are illustrated on a macroscopic model for the singlet state of a quantum system of two entangled spin 1/2 with a parameter reflecting indeterminism in the measurement procedure. By varying this parameter we describe situations from quantum, intermediate to classical and study which tests are compatible or separated. We prove that for classical deterministic systems the concepts of separability and compatibility coincide, but for quantum systems and intermediate systems these concepts are generally different.
Recent scattering experiments in the 3D Kitaev magnet $\beta$-Li$_2$IrO$_3$ have shown that a relatively weak magnetic field along the crystallographic ${\bf b}$-axis drives the system from its incommensurate counter-rotating order to a correlated paramagnet, with a significant uniform `zigzag' component superimposing the magnetization along the field. Here it is shown that the zigzag order is not emerging from its linear coupling to the field (via a staggered, off-diagonal element of the ${\bf g}$-tensor), but from its intertwining with the incommensurate order and the longitudinal magnetization. The emerging picture explains all qualitative experimental findings at zero and finite fields, including the rapid decline of the incommensurate order with field and the so-called intensity sum rule. The latter are shown to be independent signatures of the smallness of the Heisenberg exchange $J$, compared to the Kitaev coupling $K$ and the off-diagonal anisotropy $\Gamma$. Remarkably, in the regime of interest, the field $H^\ast$ at which the incommensurate component vanishes, depends essentially only on $J$, which allows to extract an estimate of $J\!\simeq\!4K$ from reported measurements of $H^\ast$. We also comment on recent experiments in pressurized $\beta$-Li$_2$IrO$_3$ and conclude that $J$ decreases with pressure.
High-fidelity and robust quantum manipulation is the key for scalable quantum computation. Therefore, due to the intrinsic operational robustness, quantum manipulation induced by geometric phases is one of the promising candidates. However, the longer gate time for geometric operations and more physical-implementation difficulties hinder its practical and wide applications. Here, we propose a simplified implementation of universal holonomic quantum gates on superconducting circuits with experimentally demonstrated techniques, which can remove the two main challenges by introducing the time-optimal control into the construction of quantum gates. Remarkably, our scheme is also based on a decoherence-free subspace encoding, with minimal physical qubit resource, which can further immune to error caused by qubit-frequency drift, which is regarded as the main error source for large scale superconducting circuits. Meanwhile, we deliberately design the quantum evolution to eliminate gate error caused by unwanted leakage sources. Therefore, our scheme is more robust than the conventional ones, and thus provides a promising alternative strategy for scalable fault-tolerant quantum computation.
Let $\lambda$ denote the Liouville function. Assuming the Riemann Hypothesis, we prove that $$\int_X^{2X}\Big|\sum_{x\leq n \leq x+h}\lambda(n) \Big|^2 dx \ll Xh(\log X)^6,$$ as $X\rightarrow \infty$, provided $h=h(X)\leq \exp\left(\sqrt{\left(\frac{1}{2}-o(1)\right)\log X \log\log X}\right).$ The proof uses a simple variation of the methods developed by Matom{\"a}ki and Radziwi{\l}{\l} in their work on multiplicative functions in short intervals, as well as some standard results concerning smooth numbers.
We study the effects of time uncertainty in the interaction of atoms with a standing light wave. We discuss its physical origin and the possibility to observe intrinsic decoherence effects by measuring the atomic momentum distribution.
We use a Pohlmeyer type reduction to generate classical string solutions in AdS spacetime. In this framework we describe a correspondence between spikes in AdS_3 and soliton profiles of the sinh-Gordon equation. The null cusp string solution and its closed spinning string counterpart are related to the sinh-Gordon vacuum. We construct classical string solutions corresponding to sinh-Gordon solitons, antisolitons and breathers by the inverse scattering technique. The breather solutions can also be reproduced by the sigma model dressing method.
The space mission CoRoT provides us with a large amount of high-duty cycle long-duration observations. Mode fitting has proven to be efficient for the complete and detailed analysis of the oscillation pattern, but remains time consuming. Furthermore, the photometric background due to granulation severely complicates the analysis. Therefore, we attempt to provide an alternative to mode fitting, for the determination of large separations. With the envelope autocorrelation function and a dedicated filter, it is possible to measure the variation of the large separation independently for the ridges with even and odd degrees. The method appears to be as accurate as the mode fitting. It can be very easily implemented and is very rapid.
We first present an intersection theory of partial differential varieties with quasi-generic differential hypersurfaces. Then based on the generic intersection theory, we define the partial differential Chow form for an irreducible partial differential variety $V$ of Kolchin polynomial $\omega_V(t)=(d+1){t+m\choose m}-{t+m-s\choose m}$. And we establish for the partial differential Chow form most of the basic properties of the ordinary differential Chow form. Furthermore, we prove the existence of a type of partial differential Chow varieties.
The third Fermi-LAT catalog (3FGL) presented the data of the first four years of observations from the Fermi Gamma-ray Space Telescope mission. There are 3034 sources, 1010 of which still remain unidentified. Identifying and classifying gamma-ray emitters is of high significance with regard to studying high-energy astrophysics. We demonstrate that optical polarimetry can be an advantageous and practical tool in the hunt for counterparts of the unidentified gamma-ray sources (UGSs). Using data from the RoboPol project, we validated that a significant fraction of active galactic nuclei (AGN) associated with 3FGL sources can be identified due to their high optical polarization exceeding that of the field stars. We performed an optical polarimetric survey within $3\sigma$ uncertainties of four unidentified 3FGL sources. We discovered a previously unknown extragalactic object within the positional uncertainty of 3FGL J0221.2+2518. We obtained its spectrum and measured a redshift of $z=0.0609\pm0.0004$. Using these measurements and archival data we demonstrate that this source is a candidate counterpart for 3FGL J0221.2+2518 and most probably is a composite object: a star-forming galaxy accompanied by AGN. We conclude that polarimetry can be a powerful asset in the search for AGN candidate counterparts for unidentified Fermi sources. Future extensive polarimetric surveys at high galactic latitudes (e.g., PASIPHAE) will allow the association of a significant fraction of currently unidentified gamma-ray sources.
Let G be a compact connected Lie group which is equipped with a bi-invariant Riemannian metric. Let m(x,y)=xy be the multiplication operator. We show the associated fibration m mapping GxG to G is a Riemannian submersion with totally geodesic fibers and we study the spectral geometry of this submersion. We show the pull back of eigenforms on the base have finite Fourier series on the total space and we give examples where arbitrarily many Fourier coefficients can be non-zero. We give necessary and sufficient conditions that the pull back of a form on the base is harmonic on the total space.
Monte Carlo simulations based on an integration scheme for free energy differences is used to compute critical Casimir forces for three-dimensional Ising films with various boundary fields. We study the scaling behavior of the critical Casimir force, including the scaling variable related to the boundary fields. Finite size corrections to scaling are taken into account. We pay special attention to that range of surface field strengths within which the force changes from repulsive to attractive upon increasing the temperature. Our data are compared with other results available in the literature.