ShantanuT01/DACTYL-Pretraining huggingface dataset:
Bound states of the power-law and logarithmic potentials are calculated using a generalized pseudospectral method. The solution of the single-particle Schr\"odinger equation in a nonuniform and optimal spatial discretization offers accurate eigenvalues, densities and expectation values. The calculations are carried out for states with arbitrary $n$ and $\ell$ quantum numbers. Comparisons are made with the available literature data and excellent agreement is observed. In all the cases, the present method yields considerably improved results over the other existing calculations. Some new states are reported.
We present new results for a sample of 33 narrow-lined UV-selected active galactic nuclei (AGNs), identified in the course of a spectroscopic survey for star-forming galaxies at z ~ 2-3. The rest-frame UV composite spectrum for our AGN sample shows several emission lines characteristic of AGNs, as well as interstellar absorption features seen in star-forming Lyman Break Galaxies (LBGs). We report a detection of NIV]1486, which has been observed in high-redshift radio galaxies, as well as in rare optically-selected quasars. The UV continuum slope of the composite spectrum is significantly redder than that of a sample of non-AGN UV-selected star forming galaxies. Blueshifted SiIV absorption provides evidence for outflowing highly-ionized gas in these objects at speeds of ~ 10^(3) km/s, quantitatively different from what is seen in the outflows of non-AGN LBGs. Grouping the individual AGNs by parameters such as Ly-alpha equivalent width, redshift, and UV continuum magnitude allows for an analysis of the major spectroscopic trends within the sample. Stronger Ly-alpha emission is coupled with weaker low-ionization absorption, which is similar to what is seen in the non-AGN LBGs, and highlights the role that cool interstellar gas plays in the escape of Ly-alpha photons. However, the AGN composite does not show the same trends between Ly-alpha strength and extinction seen in the non-AGN LBGs. These results represent the first such comparison at high-redshift between star-forming galaxies and similar galaxies that host AGN activity.
In this paper, we tackle the problem of incrementally learning a classifier, one example at a time, directly on chip. To this end, we propose an efficient hardware implementation of a recently introduced incremental learning procedure that achieves state-of-the-art performance by combining transfer learning with majority votes and quantization techniques. The proposed design is able to accommodate for both new examples and new classes directly on the chip. We detail the hardware implementation of the method (implemented on FPGA target) and show it requires limited resources while providing a significant acceleration compared to using a CPU.
Understanding the domain wall (DW) dynamics in magnetic nanowires (NW) is crucial for spintronic-based applications demanding the use of DWs as information carriers. This work focuses on the dynamics of a DW displacing along a bent NW with an elliptical shape under the action of spin-polarized electric currents and external magnetic fields. Our results evidence that a curvature gradient induces an exchange-driven effective tangential field responsible for pinning a DW near the maximum curvature point in a NW. The DW equilibrium position depends on the competition between the torques produced by the external stimuli and the curvature-induced effective fields. When the external stimuli are below a certain threshold, the DW follows a damped harmonic oscillation around the equilibrium position. Above this threshold, DW displaces along the NW under an oscillatory translational motion.
The introduced earlier projection method for boost-invariant and cylindrically symmetric systems is used to introduce a new formulation of anisotropic hydrodynamics that allows for three substantially different values of pressure acting locally in three different directions. Our considerations are based on the Boltzmann kinetic equation with the collision term treated in the relaxation time approximation and the momentum anisotropy is included explicitly in the leading term of the distribution function. A novel feature of our work is the complete analysis of the second moment of the Boltzmann equation, in addition to the zeroth and first moments that have been analyzed in earlier studies. We define the final equations of anisotropic hydrodynamics in the leading order as a subset of the analyzed moment equations (and their linear combinations) which agree with the Israel-Stewart theory in the case of small pressure anisotropies.
We report the investigations of crystal structure, electrical resistivity, magnetization, specific heat, thermal conductivity, and thermoelectric power (TEP) on La0.7Sr0.3(Mn1-xRux)O3 (LSMRO) compounds with x = 0 to 0.90. From the analyses of crystal structure and magnetization measurements, it is inferred that Ru should have a mixed valence of Ru3+ and Ru4+ for LSMRO with low level of Ru substitution, and an additional mixed valence of Ru4+ and Ru5+ with higher Ru substitution. It is found that all measured physical properties undergo pronounced anomalies due to the ferromagnetic-paramagnetic phase transition, and the observed transport properties of LSMRO can be reasonably understood from the viewpoint of polaronic transport. The Curie temperatures TC determined from the magnetization measurements are consistently higher than those of the metal-insulator transitions TMI determined from the transport measurements. By replacing Mn with Ru, both TC and TMI decrease concurrently and the studied materials are driven toward the insulating phase with larger value of x. It is also found that the entropy change during the phase transition is reduced with more Ru substitution. These observations indicate that the existence of Ru has the effect of weakening the ferromagnetism and metallicity of the LSMRO perovskites.
In order to understand the cosmic ray propagation mechanism in galaxies, and its correlation with the sites of star formation, we compare the spatially resolved radio spectral index of three spiral galaxies with their IR distribution. We present new low-frequency radio continuum observations of the galaxies NGC 0628, NGC 3627, and NGC 7331, taken at 327 MHz with the Very Large Array. We complemented our data set with sensitive archival observations at 1.4 GHz and we studied the variations of the radio spectral index within the disks of these spiral galaxies. We also compared the spectral index distribution and the IR distribution, using 70 $\mu$m Spitzer observations. We found that in these galaxies the non-thermal spectral index is anticorrelated with the radio brightness. Bright regions, like the bar in NGC 3627 or the circumnuclear region in NGC 7331, are characterized by a flatter spectrum with respect to the underlying disk. Therefore, a systematic steepening of the spectral index with the increasing distance from the center of these galaxies is observed. Furthermore, by comparing the radio images with the 70 $\mu$m images of the Spitzer satellite we found that a similar anticorrelation exists between the radio spectral index and the infrared brightness, as expected on the basis of the local correlation between the radio continuum and the infrared emission. Our results support the idea that in regions of intense star formation the electron diffusion must be efficient. The observed anticorrelation between radio brightness and spectral index, may imply that the cosmic ray density and the magnetic field strength are significantly higher in these regions than in their surroundings.
The loop structure of two point Green's functions is investigated in the Wess-Zumino model in the formalism where the auxiliary fields are integrated out. In the usual frame of perturbation theory the deviation from the non-renormalization theorem is explicitly shown. It is shown that Ward identity are not satisfied in this approach. Further we go beyond perturbation theory by solving a system of regularized Schwinger-Dyson equations (SDEs). The mass splitting between fermions and bosons, which was already observed in perturbation theory level, is further enhanced.
We solve the single particle Dirac bound state equation with a particular confining potential and comment its significance from the point of view of the quantum field theory. We show that the solutions describe a complex physical system made of a free particle and of an effective field representing the confining potential.
In addition to the Larmor radiation known from classical electrodynamics, electrons in a laser field may emit pairs of entangled photons -- which is a pure quantum effect. We investigate this quantum effect and discuss why it is suppressed in comparison with the classical Larmor radiation (which is just Thomson backscattering of the laser photons). Further, we provide an intuitive explanation of this process (in a simplified setting) in terms of the Unruh effect.
We discuss the dynamical polarization, optical response in low-frequency regime under in-plane polarized driving field of the silicene. The dynamical polarization, dielectric function, and absorption of radiation in infrared region are obtained and shown in the ${\bf q}\sim\omega$ space, and they are distinguishing for the cases of chemical potential larger than the band gap and smaller than the band gap. The optical properties of silicene and the related group-V and group-VI materials: MoS$_{2}$ and black phosphorus are explored through the first-principle study. The plasmon which damped into the electron-hole pair in the single-particle excitation regime is also mentioned. The spin/valley polarized electron-hole pairs can be formed through that way, especially for the high-energy $\pi$-plasmon which begin to damp at the small ${\bf q}$-limit. The anisotropic effects induced by the warping structure or charged impurity, and the anisotropic polarization induced by the polarized incident light are also discussed. Our result exhibits the great potential in the optoelectronic applications of the materials we discussed.
We demonstrate electrical control of the A-exciton interband transition in mono- and few-layer $MoS_{2}$ crystals embedded into photocapacitor devices via the DC Stark effect. Electric field dependent low-temperature photoluminescence spectroscopy reveals a significant tuneability of the A-exciton transition energy, up to $\sim 16 meV$, from which we extract the mean DC exciton polarisability $<\bar{\beta}>_{N} = (0.58 \pm 0.25) \cdot 10^{-8} DmV^{-1}$. The exciton polarisability is shown to be layer-independent, indicating a strong localisation of both electron and hole wave functions in each individual layer.
A generalised Weber function is given by $\w_N(z) = \eta(z/N)/\eta(z)$, where $\eta(z)$ is the Dedekind function and $N$ is any integer; the original function corresponds to $N=2$. We classify the cases where some power $\w_N^e$ evaluated at some quadratic integer generates the ring class field associated to an order of an imaginary quadratic field. We compare the heights of our invariants by giving a general formula for the degree of the modular equation relating $\w_N(z)$ and $j(z)$. Our ultimate goal is the use of these invariants in constructing reductions of elliptic curves over finite fields suitable for cryptographic use.
We study the isospin asymmetry as an observable in exclusive B -> K* gamma decay that can be used to study the effects of physics beyond the Standard Model. We present predictions for isospin asymmetry in Supersymmetric extension of the Standard Model with minimal flavor violation, using parameter values allowed by current experimental constraints. This observable can provide very tight constraints on the mSUGRA parameter space.
We study a series of X-ray-bright, rapidly-evolving active-region coronal jets outside the leading sunspot of AR 12259, using Hinode/XRT, SDO/AIA and HMI, and IRIS data. The detailed evolution of such rapidly evolving "violent" jets remained a mystery after our previous investigation of active region jets (Sterling et al. 2016, Paper 1). The jets we investigate here erupt from three localized subregions, each containing a rapidly evolving (positive) minority-polarity magnetic-flux patch bathed in a (majority) negative-polarity magnetic-flux background. At least several of the jets begin with eruptions of what appear to be thin (thickness <~2") miniature-filament (minifilament) "strands" from a magnetic neutral line where magnetic flux cancelation is ongoing, consistent with the magnetic configuration presented for coronal-hole jets in Sterling et al. (2015). Some jets strands are difficult/impossible to detect, perhaps due to, e.g. their thinness, obscuration by surrounding bright or dark features, or the absence of erupting cool-material minifilaments in those jets. Tracing in detail the flux evolution in one of the subregions, we find bursts of strong jetting occurring only during times of strong flux cancelation. Averaged over seven jetting episodes, the cancelation rate was ~1.5x10^19 Mx/hr. An average flux of ~5x10^18 Mx canceled prior to each episode, arguably building up ~10^28 - 10^29 ergs of free magnetic energy per jet. From these and previous observations, we infer that flux cancelation is the fundamental process responsible for the pre-eruption buildup and triggering of at least many jets in active regions, quiet regions, and coronal holes.
The quantum ferromagnetic transition at zero temperature in disordered itinerant electron systems is considered. Nonmagnetic quenched disorder leads to diffusive electron dynamics that induces an effective long-range interaction between the spin or order parameter fluctuations of the form r^{2-2d}, with d the spatial dimension. This leads to unusual scaling behavior at the quantum critical point, which is determined exactly. In three-dimensional systems the quantum critical exponents are substantially different from their finite temperature counterparts, a difference that should be easily observable. Experiments to check these predictions are proposed.
We show that the pairing on de Rham realizations of 1-motives in "Theorie di Hodge III", IHES 44, can be defined over any base scheme and we prove that it gives rise to a perfect duality if one is working with a 1-motive and its Cartier dual. Furthermore we study universal extensions of 1-motives and their relation with $\natural$-extensions.
In this paper we find a pathwise decomposition of a certain class of Brownian semistationary processes ($\mathcal{BSS}$) in terms of fractional Brownian motions. To do this, we specialize in the case when the kernel of the $\mathcal{BSS}$ is given by $\varphi_{\alpha}\left(x\right)=L\left(x\right)x^{\alpha}$ with $\alpha\in(-1/2,0)\cup(0,1/2)$ and $L$ a continuous function slowly varying at zero. We use this decomposition to study some path properties and derive It\^o's formula for this subclass of $\mathcal{BSS}$ processes.
A real binary tensor consists of $2^d$ real entries arranged into hypercube format $2^{\times d}$. For $d=2$, a real binary tensor is a $2\times 2$ matrix with two singular values. Their product is the determinant. We generalize this formula for any $d\ge 2$. Given a partition $\mu\vdash d$ and a $\mu$-symmetric real binary tensor $t$, we study the distance function from $t$ to the variety $X_{\mu,\mathbb{R}}$ of $\mu$-symmetric real binary tensors of rank one. The study of the local minima of this function is related to the computation of the singular values of $t$. Denoting with $X_\mu$ the complexification of $X_{\mu,\mathbb{R}}$, the Euclidean Distance polynomial $\mathrm{EDpoly}_{X_\mu^\vee,t}(\epsilon^2)$ of the dual variety of $X_\mu$ at $t$ has among its roots the singular values of $t$. On one hand, the lowest coefficient of $\mathrm{EDpoly}_{X_\mu^\vee,t}(\epsilon^2)$ is the square of the $\mu$-discriminant of $t$ times a product of sum of squares polynomials. On the other hand, we describe the variety of $\mu$-symmetric binary tensors that do not admit the maximum number of singular values, counted with multiplicity. Finally, we compute symbolically all the coefficients of $\mathrm{EDpoly}_{X_\mu^\vee,t}(\epsilon^2)$ for tensors of format $2\times 2\times 2$.
In the framework of SU(2) singlet down type vectorlike quark model, we present a comprehensive analysis for decays B-> X_s \gamma, B->X_sl^+l^- and B-> K\pi. As for B-> X_s\gamma, we include the QCD running from the mass of the down-type vector quark D to weak scale in the scenario with the D quark much heavier than weak scale, and find that the running effect is small. Using the recent measurements of B-> X_sl^+l^-, we extract rather stringent constraints on the size and CP violating phase of z_{sb}, i.e., the tree level FCNC coupling for b-> sZ. Within the bounds, we investigate various observables such as forward-backward asymmetry of b->s l^+ l^-, the decay rates of B ->X_s\gamma, and B\to K\pi. We find that (1) The forward-backward asymmetry may have large derivation from that of the SM and is very sensitive to z_{sb}, and thus can be useful in probing the new physics.(2) By taking experimental errors at 2\sigma level, both experimental measurements for B->X_sl^+l^- and B->K\pi decays can be explained in this model.
We report timing analysis of near-infrared (NIR), X-ray, and sub-millimeter (submm) data during a three-day coordinated campaign observing Sagittarius A*. Data were collected at 4.5 micron with the Spitzer Space Telescope, 2-8 keV with the Chandra X-ray Observatory, 3-70 keV with NuSTAR, 340 GHz with ALMA, and at 2.2 micron with the GRAVITY instrument on the Very Large Telescope Interferometer. Two dates show moderate variability with no significant lags between the submm and the infrared at 99% confidence. July 18 captured a moderately bright NIR flare (F_K ~ 15 mJy) simultaneous with an X-ray flare (F ~ 0.1 cts/s) that most likely preceded bright submm flux (F ~ 5.5 Jy) by about +34 (+14 -33) minutes at 99% confidence. The uncertainty in this lag is dominated by the fact that we did not observe the peak of the submm emission. A synchrotron source cooled through adiabatic expansion can describe a rise in the submm once the synchrotron-self-Compton NIR and X-ray peaks have faded. This model predicts high GHz and THz fluxes at the time of the NIR/X-ray peak and electron densities well above those implied from average accretion rates for Sgr A*. However, the higher electron density postulated in this scenario would be in agreement with the idea that 2019 was an extraordinary epoch with a heightened accretion rate. Since the NIR and X-ray peaks can also be fit by a non-thermal synchrotron source with lower electron densities, we cannot rule out an unrelated chance coincidence of this bright submm flare with the NIR/X-ray emission.
We present results from an analysis of stellar population parameters for 7132 galaxies in the 6dFGS Fundamental Plane (FP) sample. We bin the galaxies along the axes, $v_1$, $v_2$, and $v_3$, of the tri-variate Gaussian to which we have fit the galaxy distribution in effective radius, surface brightness, and central velocity dispersion (FP space), and compute median values of stellar age, [Fe/H], [Z/H], and [$\alpha$/Fe]. We determine the directions of the vectors in FP space along which each of the binned stellar population parameters vary most strongly. In contrast to previous work, we find stellar population trends not just with velocity dispersion and FP residual, but with radius and surface brightness as well. The most remarkable finding is that the stellar population parameters vary through the plane ($v_1$ direction) and across the plane ($v_3$ direction), but show no variation at all along the plane ($v_2$ direction). The $v_2$ direction in FP space roughly corresponds to `luminosity density'. We interpret a galaxy's position along this vector as being closely tied to its merger history, such that early-type galaxies with lower luminosity density are more likely to have undergone major mergers. This conclusion is reinforced by an examination of the simulations of Kobayashi (2005), which show clear trends of merger history with $v_2$.
Employing a combination of symmetry analysis, low-energy modeling, and ab initio simulations, we predict the presence of magnetic-field-induced Weyl points close to the Fermi level in CaKFe$_4$As$_4$. Depending on the relative strengths of the magnetic field and of the spin-orbit coupling, the Weyl fermions can carry a topological charge of $\pm1$ or $\pm2$, making CaKFe$_4$As$_4$ a rare realization of a double-Weyl semimetal. We further predict experimental manifestations of these Weyl points, both in bulk properties, such as the anomalous Hall effect, and in surface properties, such as the emergence of prominent Fermi arcs. Because CaKFe$_4$As$_4$ displays unconventional fully-gapped superconductivity below 30 K, our findings open a novel route to investigate the interplay between superconductivity and Weyl fermions.
In this paper, we investigate the emission properties of PSR J1727-2739, whose mean pulse profile has two main components, by analysing five single-pulse observations made using the Parkes 64-m radio telescope with a central frequency of 1369 MHz between 2014 April and October. The total observation time is about 6.1 hours which contains 16718 pulses after removal of radio frequency interference (RFI). Previous studies reveal that PSR J1727-2739 exhibits both nulling and subpulse drifting. We estimate the nulling fraction to be 66%, which is consistent with previously published results. In addition to the previously known subpulse drifting in the leading component, we also explore the drifting properties for the trailing component. We observe two distinct drift modes whose vertical drift band separations ($P_{3}$) are consistent with earlier studies. We find that both profile components share the same drift periodicity $P_{3}$ in a certain drift mode, but the measured horizontal separations ($P_{2}$) are quite different for them. That is, PSR J1727-2739 is a pulsar showing both changes of drift periodicity $P_{3}$ between different drift modes and drift rate variations between components in a given drift mode. Pulsars exhibiting nulling along with drift mode changing, such as PSR J1727-2739, give an unique opportunity to investigate the physical mechanism of these phenomena.
We investigate the effect of the anisotropy between the s-wave scattering lengths of a three-component atomic Fermi gas loaded into a one-dimensional optical lattice. We find four different phases which support trionic instabilities made of bound states of three fermions. These phases distinguish themselves by the relative phases between the 2$k_F$ atomic density waves fluctuations of the three species. At small enough densities or strong anisotropies we give further evidences for a decoupling and the stabilization of more conventional BCS phases. Finally our results are discussed in light of a recent experiment on $^{6}$Li atoms.
With every path on a projective line minus zero, one and infinity there is associated a measure. We are studying a sum of two such measures associated to paths from the tangential point at zero to roots of one. We show that the obtained measure can be defined very elementary. Integrating agaist this measure we get p-adic Hurwitz zeta functions constructed previously by Shiratani.
Using an exactly solvable model, we study low-energy properties of a one-dimensional spinless electron fluid contained in a quantum-mechanically moving wire located in a static magnetic field. The phonon and electric current are coupled via Lorentz force and the eigenmodes are described by two independent boson fluids. At low energies, the two boson modes are charged while one of them has excitation gap due to back-reaction of the Lorentz force. The theory is illustrated by evaluating optical absorption spectra. Our results are exact and show a non-perturbative regime of electron transport.