ShantanuT01/DACTYL-Pretraining huggingface dataset:
We present temperature dependent resistivity and ac-calorimetry measurements of CeVSb3 under pressure up to 8 GPa in a Bridgman anvil cell modified to use a liquid medium and in a diamond anvil cell using argon as a pressure medium, respectively. We observe an initial increase of the ferromagnetic transition temperature Tc with pressures up to 4.5 GPa, followed by decrease of Tc on further increase of pressure and finally its disappearance, in agreement with the Doniach model. We infer a ferromagnetic quantum critical point around 7 GPa under hydrostatic pressure conditions from the extrapolation to 0 K of Tc and the maximum of the A coefficient from low temperature fits of the resistivity \rho (T)=\rho_{0}+AT^{n}. No superconductivity under pressure was observed down to 0.35 K for this compound. In addition, differences in the Tc(P) behavior when a slight uniaxial component is present are noticed and discussed and correlated to choice of pressure medium.
We identify a recursive structure among factorizations of polynomial values into two integer factors. Polynomials for which this recursive structure characterizes all non-trivial representations of integer factorizations of the polynomial values into two parts are here called recursively-factorable polynomials. In particular, we prove that $n^2+1$ and the prime-producing polynomials $n^2+n+41$ and $2n^2+ 29$ are recursively-factorable.   For quadratics, the we prove that this recursive structure is equivalent to a Diophantine identity involving the product of two binary quadratic forms. We show that this identity may be transformed into geometric terms, relating each integer factorization $an^2+bn+c=pq$ to a lattice point of the conic section $aX^2+bXY+cY^2+X-nY=0$, and vice versa.
Let $X/\mathbb{Q}$ be a curve of genus $g \ge 2$ with Jacobian $J$ and let $\ell$ be a prime of good reduction. Using Selmer varieties, Kim defines a decreasing sequence \[ X(\mathbb{Q}_\ell) \supseteq X(\mathbb{Q}_\ell)_1 \supseteq X(\mathbb{Q}_\ell)_2 \supseteq \cdots \] all containing the rational points of $X$. Thanks to the work of Coleman, the `Chabauty set' $X(\mathbb{Q}_\ell)_1$ is known to be finite provided the Mordell--Weil rank of $J$ is smaller than $g$. In this case one has a practical strategy that often succeeds in computing the set of rational points of $X$. Balakrishnan and Dogra have recently shown that the `quadratic Chabauty set' $X(\mathbb{Q}_\ell)_2$ is finite provided the Mordell--Weil rank is less than $g + \rho-1$, where $\rho$ is the N\'eron-Severi rank of $J/\mathbb{Q}$. In view of this it is interesting to give families of curves where $\rho \ge 2$ and where therefore quadratic Chabauty is more likely to succeed than classical Chabauty. In this note we show that this is indeed the case for all modular curves of genus at least 3.
Using optical dipole forces we have realized controlled transport of a single or any desired small number of neutral atoms over a distance of a centimeter with sub-micrometer precision. A standing wave dipole trap is loaded with a prescribed number of cesium atoms from a magneto-optical trap. Mutual detuning of the counter-propagating laser beams moves the interference pattern, allowing us to accelerate and stop the atoms at preselected points along the standing wave. The transportation efficiency is close to 100%. This optical "single-atom conveyor belt" represents a versatile tool for future experiments requiring deterministic delivery of a prescribed number of atoms on demand.
We consider translation-invariant interacting particle systems on the lattice with finite local state space admitting at least one Gibbs measure as a time-stationary measure. The dynamics can be irreversible but should satisfy some mild non-degeneracy conditions. We prove that weak limit points of any trajectory of translation-invariant measures, satisfying a non-nullness condition, are Gibbs states for the same specification as the time-stationary measure. This is done under the additional assumption that zero entropy loss of the limiting measure w.r.t. the time-stationary measure implies that they are Gibbs measures for the same specification. We show how to prove the non-nullness for a large number of cases, and also give an alternate version of the last condition such that the non-nullness requirement can be dropped. As an application we obtain the attractor property if there is a reversible Gibbs measure. Our method generalizes convergence results using relative entropy techniques to a large class of dynamics including irreversible and non-ergodic ones.
We estimate the distance modulus to long gamma-ray bursts (LGRBs) using the Type I Fundamental Plane, a correlation between the spectral peak energy $E_{\rm p}$, the peak luminosity $L_{\rm p}$, and the luminosity time $T_{\rm L}$ ($\equiv E_{\rm iso}/L_{\rm p}$ where $E_{\rm iso}$ is isotropic energy) for small Absolute Deviation from Constant Luminosity(ADCL). The Type I Fundamental Plane of LGRBs is calibrated using 8 LGRBs with redshift $z<1.4$. To avoid any assumption on the cosmological model, we use the distance modulus of 557 Type Ia supernovae (SNeIa) from the Union 2 sample. This calibrated Type I Fundamental Plane is used to measure the distance moduli to 9 high-redshift LGRBs with the mean error $\bar \sigma_{\mu}=0.31$, which is comparable with that of SNe Ia $\bar \sigma_{\mu}=0.26$ where $\mu$ stands for the distance modulus. The Type I Fundamental Plane is so tight that our distance moduli have very small uncertainties. From those distance moduli, we obtained the constraint $\Omega_{\rm M}=0.22\pm0.04$ for flat $\Lambda$CDM universe. Adding 9 LGRBs distance moduli ($z>1.4$) to 557 SNeIa distance moduli ($z<1.4$) significantly improves the constraint for non-flat $\Lambda$CDM universe from ($\Omega_{\rm M}, \Omega_{\rm \Lambda}$)=($0.29\pm0.10$, $0.76\pm0.13$) for SNeIa only to ($\Omega_{\rm M}, \Omega_{\rm \Lambda}$)=($0.23\pm0.06$, $0.68\pm0.08$) for SNeIa and 9 LGRBs.
Understanding the mechanism of electroweak symmetry breaking and the origin of boson and fermion masses is among the most pressing questions raised in contemporary particle physics. If these issues involve one (several) Higgs boson(s), a precise measurement of all its (their) properties will be of prime importance. Among those, the Higgs coupling to matter fermions (the Yukawa coupling). At a Linear Collider, the process e+e- -> ttH will allow in principle a direct measurement of the top-Higgs Yukawa coupling. We present a realistic feasibility study of the measurement in the context of the TESLA collider. Four channels are studied and the analysis is repeated for several Higgs mass values within the range 120 GeV - 200 GeV.
Studies based on the gamma-ray lines from radioactive decay of unstable isotopes produced in massive-star and supernova nucleosynthesis have been among INTEGRAL's prominent science achievements. 26Al has become a tool to study specific source regions, such as massive-star groups and associations in nearby regions which can be discriminated from the galactic-plane background, and the inner Galaxy where Doppler shifted lines add to the astronomical information. 60Fe is co-produced by the sources of 26Al, and the isotopic ratio from their nucleosynthesis encodes stellar-structure information. Here we summarize latest results using the accumulated multi-year database of observations, point to the relevant publications, and discuss their astrophysical implications.
The influence of a nearest-neighbor Coulomb repulsion of strength V on the properties of the Ferromagnetic Kondo model is analyzed using computational techniques. The Hamiltonian studied here is defined on a chain using localized S=1/2 spins, and one orbital per site. Special emphasis is given to the influence of the Coulomb repulsion on the regions of phase separation recently discovered in this family of models, as well as on the double-exchange-induced ferromagnetic ground state. When phase separation dominates at V=0, the Coulomb interaction breaks the large domains of the two competing phases into small ``islands'' of one phase embedded into the other. This is in agreement with several experimental results, as discussed in the text. Vestiges of the original phase separation regime are found in the spin structure-factor as incommensurate peaks, even at large values of V. In the ferromagnetic regime close to density $n=0.5$, the Coulomb interaction induces tendencies to charge ordering without altering the fully polarized character of the state. This regime of ``charge- ordered ferromagnetism'' may be related with experimental observations of a similar phase by C. H. Chen and S-W. Cheong (Phys. Rev. Lett. 76, 4042 (1996)). Our results reinforce the recently introduction notion (see e.g., S. Yunoki et al., Phys. Rev. Lett. 80, 845 (1998)) that in realistic models for manganites analyzed with unbiased many-body techniques, the ground state properties arise from a competition between ferromagnetism and phase-separation/charge-ordering tendencies.
Doped Si is a promising candidate for quantum computing due to its scalability properties, long spin coherence times, and the astonishing progress on Si technology and miniaturization in the last few decades. This proposal for a quantum computer ultimately relies on the quantum control of electrons bound to donors near a Si/barrier (e.g. SiO2) interface. We address here several important issues and define critical parameters that establish the conditions that allow the manipulation of donor electrons in Si by means of external electric and magnetic fields.
In this paper, we establish a version of the Feynman-Kac formula for multidimensional stochastic heat equation driven by a general semimartingale. This Feynman-Kac formula is then applied to study some nonlinear stochastic heat equations driven by nonhomogenous Gaussian noise: First, it is obtained an explicit expression for the Malliavin derivatives of the solutions. Based on the representation we obtain the smooth property of the density of the law of the solution. On the other hand, we also obtain the H\"older continuity of the solutions.
Dual actions with respect to U(1) gauge fields for Born-Infeld and $Dp$-brane theories are reexamined. Taking into account an additional condition, i.e. a corollary to the field equation of the auxiliary metric, one obtains an alternative dual action that does not involve the infinite power series in the auxiliary metric given by ref. \cite{s14}, but just picks out the first term from the series formally. New effective interactions of the theories are revealed. That is, the new dual action gives rise to an effective interaction in terms of one interaction term rather than infinite terms of different (higher) orders of interactions physically. However, the price paid for eliminating the infinite power series is that the new action is not quadratic but highly nonlinear in the Hodge dual of a $(p-1)$-form field strength. This non-linearity is inevitable to the requirement the two dual actions are equivalent.
We study the existence of third, hyperdeformed minima in a number of even-even Th, U and Pu nuclei using the Woods-Saxon microscopic-macroscopic model that very well reproduces first and second minima and fission barriers in actinides. Deep ($3 \div 4$ MeV) minima found previously by \'Cwiok et al. are found spurious after sufficiently general shapes are included. Shallow third wells may exist in $^{230,232}$Th, with IIIrd barriers $\le$ 200 and 330 keV (respectively). Thus, a problem of qualitative discrepancy between microscopic-macroscopic and selfconsistent predictions is resolved. Now, an understanding of experimental results on the apparent third minima in uranium becomes an issue.
(Abridged:) Schwarzschild's method was used to construct equilibrium solutions to the collisionless Boltzmann equation corresponding to a Plummer sphere, which were compared with analytical results to test the robustness of the numerical method and its efficiency in probing the degeneracy of the solution space. The method was then used to construct triaxial equilibria with no known analytical solutions and to study their nonuniqueness. The model that was studied, the triaxial Dehnen potential, contains a central density cusp and admits both regular and chaotic orbits. It was found that, for a weak density cusp, self-consistent models do not exist if the chaotic orbits are assumed to be completely mixed so as to yield a time-independent building-block: only the innermost 65% of the mass can be mixed. In these inner regions, it is possible to obtain alternative solutions that contain significantly different numbers of chaotic orbits, yet yield (at least approximately) the same mass density distribution. However, it is not clear whether these solutions are truly time-independent, since the unmixed chaotic orbits in the outer regions, which do not sample an invariant measure, can cause secular evolution. When using Schwarzschild's method, one must be very careful to sample accessible phase space as comprehensively and as densely as possible, while ensuring that each orbit is a truly time-independent building block. Some of the numerical equilibria were sampled to generate initial conditions for N-body simulations to test the structural stability of the models. Preliminary work showed that no catastrophic evolution takes place, but there is a weak tendency for the configuration to become more nearly axisymmetric over several dynamical times. It is not yet clear whether this tendency is real or a numerical artifact.
A system manager dynamically controls a diffusion process Z that lives in a finite interval [0,b]. Control takes the form of a negative drift rate \theta that is chosen from a fixed set A of available values. The controlled process evolves according to the differential relationship dZ=dX-\theta(Z) dt+dL-dU, where X is a (0,\sigma) Brownian motion, and L and U are increasing processes that enforce a lower reflecting barrier at Z=0 and an upper reflecting barrier at Z=b, respectively. The cumulative cost process increases according to the differential relationship d\xi =c(\theta(Z)) dt+p dU, where c(\cdot) is a nondecreasing cost of control and p>0 is a penalty rate associated with displacement at the upper boundary. The objective is to minimize long-run average cost. This problem is solved explicitly, which allows one to also solve the following, essentially equivalent formulation: minimize the long-run average cost of control subject to an upper bound constraint on the average rate at which U increases. The two special problem features that allow an explicit solution are the use of a long-run average cost criterion, as opposed to a discounted cost criterion, and the lack of state-related costs other than boundary displacement penalties. The application of this theory to power control in wireless communication is discussed.
The formalism by Press and Schechter (PS) is often used to infer number densities of virialized objects of mass M (e.g. quasars, galaxies, clusters of galaxies, etc.) from a count of initially overdense regions in a Gaussian density perturbation field. We reanalyze the PS-formalism by explicitly counting underdense regions which are embedded within overdense regions, so called cloud-in-clouds. In contrast to the original PS-formalism, our revised analysis automatically accounts for all the cosmic material. We find that mass distribution functions for virialized objects are altered by the proper solution of the cloud-in-cloud problem. These altered distribution functions agree much better with distribution functions inferred form N-body simulations than the original PS-distribution functions.
In this paper, we derive a new differential homography that can account for the scanline-varying camera poses in Rolling Shutter (RS) cameras, and demonstrate its application to carry out RS-aware image stitching and rectification at one stroke. Despite the high complexity of RS geometry, we focus in this paper on a special yet common input -- two consecutive frames from a video stream, wherein the inter-frame motion is restricted from being arbitrarily large. This allows us to adopt simpler differential motion model, leading to a straightforward and practical minimal solver. To deal with non-planar scene and camera parallax in stitching, we further propose an RS-aware spatially-varying homography field in the principle of As-Projective-As-Possible (APAP). We show superior performance over state-of-the-art methods both in RS image stitching and rectification, especially for images captured by hand-held shaking cameras.
We apply a variant of the multigrade efficient congruencing method to estimate Vinogradov's integral of degree $3$ for moments of order $2s$, establishing strongly diagonal behaviour for $1\le s\le 6$. Consequently, the main conjecture is now known to hold for the first time in a case of degree exceeding $2$.
A list of known Galactic field stars exhibiting Blazhko effect containing 242 stars is presented. All the entries including their designations, positions, pulsation, and Blazhko periods were collected from the available literature. The actual values of parameters are given.
The calculations of the potential energy surface are essential in the theoretical description of the fission process. In the constrained self-consistent approach, the smooth evolution of nuclear shape is described from the ground state until a very elongated one with a narrow neck. In all microscopic calculations, the rupture of the neck at scission is associated with a substantial change of nuclear matter density distribution and rapid energy decrease. In this paper, we show that there is no discontinuity of the potential energy surface at scission when multi-constrained calculations are applied with the neck constraint. An early rupture of the neck at lower quadrupole and octupole moments is discussed as competitive with the conventional fission path. We discuss the neck properties in the scission configuration. We find that the neck radius in the asymmetric fission mode cannot decrease below 2 fm, and the nuclear matter density cannot decrease below the saturation density. In the compact fission mode, nuclear density may go down to half of the saturation density before the rupture of the neck.
The Fano-Kondo effect in zero-bias conductance is investigated based on a theoretical model for the T-shaped quantum dot. The conductance as a function of the gate voltage is generally characterized by a Fano asymmetric parameter q. With varying temperature the conductance shows a crossover between the high and low temperature regions compared with the Kondo temperature T_K: two Fano asymmetric peaks at high temperatures and the Fano-Kondo plateau inside a Fano peak at low temperatures. Temperature dependence of conductance is calculated numerically by the Finite temperature density matrix renormalization group method (FT-DMRG).
Defect lines in conformal field theory can be perturbed by chiral defect fields. If the unperturbed defects satisfy su(2)-type fusion rules, the operators associated to the perturbed defects are shown to obey functional relations known from the study of integrable models as T-systems. The procedure is illustrated for Virasoro minimal models and for Liouville theory.
We study the properties of Dirac fermions on the surface of a topological insulator in the presence of crossed electric and magnetic fields. We provide an exact solution to this problem and demonstrate that, in contrast to their counterparts in graphene, these Dirac fermions allow relative tuning of the orbital and Zeeman effects of an applied magnetic field by a crossed electric field along the surface. We also elaborate and extend our earlier results on normal metal-magnetic film-normal metal (NMN) and normal metal-barrier-magnetic film (NBM) junctions of topological insulators [Phys. Rev. Lett. {\bf 104}, 046403 (2010)]. For NMN junctions, we show that for Dirac fermions with Fermi velocity $v_F$, the transport can be controlled using the exchange field ${\mathcal J}$ of a ferromagnetic film over a region of width $d$. The conductance of such a junction changes from oscillatory to a monotonically decreasing function of $d$ beyond a critical ${\mathcal J}$ which leads to the possible realization of magnetic switches using these junctions. For NBM junctions with a potential barrier of width $d$ and potential $V_0$, we find that beyond a critical ${\mathcal J}$, the criteria of conductance maxima changes from $\chi= e V_0 d/\hbar v_F = n \pi$ to $\chi= (n+1/2)\pi$ for integer $n$. Finally, we compute the subgap tunneling conductance of a normal metal-magnetic film-superconductor (NMS) junctions on the surface of a topological insulator and show that the position of the peaks of the zero-bias tunneling conductance can be tuned using the magnetization of the ferromagnetic film. We point out that these phenomena have no analogs in either conventional two-dimensional materials or Dirac electrons in graphene and suggest experiments to test our theory.
Infrared, visible and near-UV reflectivity measurements are used to obtain conductivity as a function of temperature and frequency in YbInCu_4, which exhibits an isostructural phase-transition into a mixed-valent phase below T_v=42 K. In addition to a gradual loss of spectral weight with decreasing temperature extending up to 1.5 eV, a sharp resonance appears at 0.25 eV in the mixed-valent phase. This feature can be described in terms of excitations into the Kondo (Abrikosov-Suhl) resonance, and, like the sudden reduction of resistivity, provides a direct reflection of the onset of coherence in this strongly correlated electron system.
An algorithm for obtaining the Taylor coefficients of an expansion of Feynman diagrams is proposed. It is based on recurrence relations which can be applied to the propagator as well as to the vertex diagrams. As an application, several coefficients of the Taylor series expansion for the two-loop propagator and two-loop non-planar vertex diagrams are calculated. The results of the numerical evaluation of these diagrams using conformal mapping and Pade approximants are given.
We present new upper limits on the volume-weighted neutral hydrogen fraction, <xHI>, at z~5-6 derived from spectroscopy of bright quasars. The fraction of the Lyman-alpha and Lyman-beta forests that is "dark" (with zero flux) provides the only model-independent upper limit on <xHI>, requiring no assumptions about the physical conditions in the intergalactic medium or the quasar's unabsorbed UV continuum. In this work we update our previous results using a larger sample (22 objects) of medium-depth (~ few hours) spectra of high-redshift quasars obtained with the Magellan, MMT, and VLT. This significantly improves the upper bound on <xHI> derived from dark pixel analysis to <xHI> <= 0.06 + 0.05 (1{\sigma}) at z=5.9, and <xHI> <= 0.04 + 0.05 (1{\sigma}) at z=5.6. These results provide robust constraints for theoretical models of reionization, and provide the strongest available evidence that reionization has completed (or is very nearly complete) by z~6.
We present current noise measurements in a long diffusive superconductor-normal-metal-superconductor junction in the low voltage regime, in which transport can be partially described in terms of coherent multiple Andreev reflections. We show that, when decreasing voltage, the current noise exhibits a strong divergence together with a broad peak. We ascribe this peak to the mixing between the ac- Josephson current and the noise of the junction itself. We show that the junction noise corresponds to the thermal noise of a nonlinear resistor 4kBT=R with R V = I V and no adjustable parameters.