ShantanuT01/DACTYL-Pretraining huggingface dataset:
Spin supersolids and spin superfluids reveal complex canted spin structures with independent order of longitudinal and transverse spin components. This work addresses the question whether these exotic phases can exhibit spin-driven ferroelectricity. Here we report the results of dielectric and pyrocurrent measurements of MnCr2S4 as function of temperature and magnetic field up to 60 T. This sulfide chromium spinel exhibits a Yafet-Kittel type canted spin structure at low temperatures. As function of external magnetic field, the manganese spins undergo a sequence of ordering patterns of the transverse and longitudinal spin components, which can be mapped onto phases as predicted by lattice-gas models including solid, liquid, super-fluid, and supersolid phases. By detailed dielectric and pyrocurrent measurements, we document a zoo of multiferroic phases with sizable ferroelectric polarization strongly varying from phase to phase. Using lattice-gas terminology, the title compound reveals multiferroic spin-superfluid and spin-supersolid phases, while the antiferromagnetic solid is paraelectric.
We establish a link between an angle of the neutron polarization rotation in a crystal diffraction experiment and constants of the P-,T- violating interactions. The consideration applies to the energy range of thermal and resonance neutrons.
Results of recent observations of the Galactic bulge demand that we discard a simple picture of its formation, suggesting the presence of two stellar populations represented by two peaks of stellar metallicity distribution (MDF) in the bulge. To assess this issue, we construct Galactic chemical evolution models that have been updated in two respects: First, the delay time distribution (DTD) of type Ia supernovae (SNe Ia) recently revealed by extensive SN Ia surveys is incorporated into the models. Second, the nucleosynthesis clock, the s-processing in asymptotic giant branch (AGB) stars, is carefully considered in this study. This novel model first shows that the Galaxy feature tagged by the key elements, Mg, Fe, Ba for the bulge as well as thin and thick disks is compatible with a short-delay SN Ia. We present a successful modeling of a two-component bulge including the MDF and the evolutions of [Mg/Fe] and [Ba/Mg], and reveal its origin as follows. A metal-poor component (<[Fe/H]>~-0.5) is formed with a relatively short timescale of ~1 Gyr. These properties are identical to the thick disk's characteristics in the solar vicinity. Subsequently from its remaining gas mixed with a gas flow from the disk outside the bulge, a metal-rich component (<[Fe/H]>~+0.3) is formed with a longer timescale (~4 Gyr) together with a top-heavy initial mass function that might be identified with the thin disk component within the bulge.
The relation between nuclear saturation and NN-correlations is examined. Nucleons bound in a nucleus have a reduced effective mass due to the mean field. This results in off-energy-shell scatterings modifying the free-space NN-interaction by a dispersion correction. This is a major contribution to the density-dependence of the effective in-medium force and to saturation. Low-momentum effective interactions have been derived by renormalisation methods whereby correlations may be reduced by effectively cutting off high momentum components of the interaction. The effect of these cut-offs on dispersive corrections and on saturation is the main focus of this paper. The role of the tensor-force, its strength and its effect on correlations is of particular interest. The importance of the definition of the mean field in determining saturation as well as compressibility is also pointed out.   With a cut-off below $\sim 2.6 fm^{-1}$ there is no saturation but at lower density the binding energy is still well approximated suggesting that such a force may be useful in nuclear structure calculations of (small) finite nuclei if saturation is not an issue.   A separable interaction that fits experimental phase-shifts exactly by inverse scattering methods is used. Recent experiments measure short ranged correlations (SRC's) to be 0.23 for $^{56}Fe$. Other experiments have obtained a depletion of occupation-numbers in $^{208}Pb$ to be $\sim 0.2$. For nuclear matter with the separable interaction and a continuous spectrum we obtain the related quantity $\kappa$ to be 0.175 with the Bonn-B deuteron parameters, while Machleidt's gets $\kappa= 0.125$ for the Bonn-B potential and a continuous spectrum.
The problems related to the management of large quantum registers could be handled in the context of distributed quantum computation: unitary non-local transformations among spatially separated local processors are realized performing local unitary transformations and exchanging classical communication. In this paper, we propose a scheme for the implementation of universal non-local quantum gates such as a controlled-$\gate{NOT}$ ($\cnot$) and a controlled-quantum phase gate ($\gate{CQPG}$). The system we have chosen for their physical implementation is a Cavity-Quantum-Electro-Dynamics (CQED) system formed by two spatially separated microwave cavities and two trapped Rydberg atoms. We describe the procedures to follow for the realization of each step necessary to perform a specific non-local operation.
In the paper: Fans in the Theory of Real Semigroups. I. Algebraic Theory (submitted) we introduced the notion of fan in the categories of real semigoups and their dual abstract real spectra and developed the algebraic theory of these structures. In this paper we develop the combinatorial theory of ARS-fans, i.e., fans in the dual category of abstract real spectra. Every ARS is a spectral space and hence carries a natural partial order called the {\it specialization partial order}. Our main result shows that the isomorphism type of a finite fan in the category ARS is entirely determined by its order of specialization. The main tools used to prove this result are: (1) Crucial use of the theory of {\it ternary semigroups}, a class of semigroups underlying that of RSs; (2) Every ARS-fan is a disjoint union of abstract order spaces (called {\it levels}); (3) Every level carries a natural involution of abstract order spaces, and (4) The notion of a {\it standard generating system}, a combinatorial tool replacing, in the context of ARSs, the (absent) tools of combinatorial geometry (matroid theory) employed in the cases of fields and of abstract order spaces.
The "no hair" theorem, a key result in General Relativity, states that an isolated black hole is defined by only three parameters: mass, angular momentum, and electric charge; this asymptotic state is reached on a light-crossing time scale. We find that the "no hair" theorem is not formally applicable for black holes formed from collapse of a rotating neutron star. Rotating neutron stars can self-produce particles via vacuum breakdown forming a highly conducting plasma magnetosphere such that magnetic field lines are effectively "frozen-in" the star both before and during collapse. In the limit of no resistivity, this introduces a topological constraint which prohibits the magnetic field from sliding off the newly-formed event horizon. As a result, during collapse of a neutron star into a black hole, the latter conserves the number of magnetic flux tubes $N_B = e \Phi_\infty /(\pi c \hbar)$, where $\Phi_\infty \approx 2 \pi^2 B_{NS} R_{NS}^3 /(P_{\rm NS} c)$ is the initial magnetic flux through the hemispheres of the progenitor and out to infinity. We test this theoretical result via three-dimensional general relativistic plasma simulations of rotating black holes that start with a neutron star dipole magnetic field with no currents initially present outside the event horizon. The black hole's magnetosphere subsequently relaxes to the split monopole magnetic field geometry with self-generated currents outside the event horizon. The dissipation of the resulting equatorial current sheet leads to a slow loss of the anchored flux tubes, a process that balds the black hole on long resistive time scales rather than the short light-crossing time scales expected from the vacuum "no-hair" theorem.
In this work we calculate the meson loop effects on the pion electromagnetic form factor and perform a comparison with experimental data. We show that, even though the meson cloud is not the only nonperturbative process to be considered, its contribution is significant.
In 1848 Ch.~Hermite asked if there exists some way to write cubic irrationalities periodically. A little later in order to approach the problem C.G.J.~Jacobi and O.~Perron generalized the classical continued fraction algorithm to the three-dimensional case, this algorithm is called now the Jacobi-Perron algorithm. This algorithm is known to provide periodicity only for some cubic irrationalities.   In this paper we introduce two new algorithms in the spirit of Jacobi-Perron algorithm: the heuristic algebraic periodicity detecting algorithm and the $\sin^2$-algorithm. The heuristic algebraic periodicity detecting algorithm is a very fast and efficient algorithm, its output is periodic for numerous examples of cubic irrationalities, however its periodicity for cubic irrationalities is not proven. The $\sin^2$-algorithm is limited to the totally-real cubic case (all the roots of cubic polynomials are real numbers). In the recent paper~\cite{Karpenkov2021} we proved the periodicity of the $\sin^2$-algorithm for all cubic totally-real irrationalities. To our best knowledge this is the first Jacobi-Perron type algorithm for which the cubic periodicity is proven. The $\sin^2$-algorithm provides the answer to Hermite's problem for the totally real case (let us mention that the case of cubic algebraic numbers with complex conjugate roots remains open).   We conclude this paper with one important application of Jacobi-Perron type algorithms to computation of independent elements in the maximal groups of commuting matrices of algebraic irrationalities.
Phonons (collective atomic vibrations in solids) are more effective in transporting heat than photons. This is the reason why the conduction mode of heat transport in nonmetals (mediated by phonons) is dominant compared to the radiation mode of heat transport (mediated by photons). However, since phonons are unable to traverse a vacuum gap (unlike photons) it is commonly believed that two bodies separated by a gap cannot exchange heat via phonons. Recently, a mechanism was proposed by which phonons can transport heat across a vacuum gap - through Van der Waals interaction between two bodies with gap less than wavelength of light. Such heat transfer mechanisms are highly relevant for heating (and cooling) of nanostructures; the heating of the flying heads in magnetic storage disks is a case in point. Here, the theoretical derivation for modeling phonon transmission is revisited and extended to the case of two bodies made of different materials separated by a vacuum gap. Magnitudes of phonon transmission, and hence the heat transfer, for commonly used materials in the micro and nano-electromechanical industry are calculated and compared with the calculation of conduction heat transfer through air for small gaps.
We present results from two {\it Chandra} observations of the 16.6 d X-ray/$\gamma$-ray high-mass binary 1FGL J1018.6$-$5856 located at the center of the supernova remnant G284.3$-$1.8. The binary spectra, separated by 0.25 in binary phase, are fit with an absorbed power-law model with $\Gamma\approx1.7-1.8$ for both observations (the flux during the second observation is a factor of 1.7 smaller). In the high-resolution ACIS-I image we found a hint of extended emission $\approx2''$--$3''$ southeast of the binary, significant at the $3\sigma$ level. Binary evolution codes reproduce the system's observed properties with two massive stars with an initial 18-day period, undergoing mass transfer and leaving behind a heavy $\approx2$ $\msun$ neutron star. The initial mass of the progenitor star in this scenario is 27 $\pm 4$ $\msun$. \emph{Chandra} and {\it XMM-Newton} images of the remnant show it has a relatively low X-ray surface brightness. The two brightest regions of extended X-ray emission, with luminosities $\sim10^{33}$ erg s$^{-1}$ for $d=5$ kpc, lie in the northern and western portions and show significantly different spectra. The northern patch is consistent with shocked ISM, with a low temperature and long ionization timescale. However, the western patch is dominated by ejecta, and shows significantly enhanced Mg content relative to other ejecta products. The abundance ratios inferred resemble those from the Large Magellanic Cloud remnant N49B. To our knowledge, this is only the second case of such Mg-rich ejecta found in an SNR. Nucleosynthesis models for core-collapse SNe predict Mg-rich ejecta from very massive progenitors of $>25$ $\msun$.
For a Coulomb system contained in a domain \Lambda, the dielectric susceptibility tensor \chi_{\Lambda} is defined as relating the average polarization in the system to a constant applied electric field, in the linear limit. According to the phenomenological laws of macroscopic electrostatics, \chi_{\Lambda} depends on the specific shape of the domain \Lambda. In this paper we derive, using the methods of equilibrium statistical mechanics in both canonical and grand-canonical ensembles, the shape dependence of \chi_{\Lambda} and the corresponding finite-size corrections to the thermodynamic limit, for a class of general \nu-dimensional (\nu\ge 2) Coulomb systems, of ellipsoidal shape, being in the conducting state. The microscopic derivation is based on a general principle: the total force acting on a system in thermal equilibrium is zero. The results are checked in the Debye-H\"uckel limit. The paper is a generalization of a previous one [L. \v{S}amaj, J. Stat. Phys. 100:949 (2000)], dealing with the special case of a one-component plasma in two dimensions. In that case, the validity of the presented formalism has already been verified at the exactly solvable (dimensionless) coupling \Gamma = 2.
The physics and the technical algorithms of the statistical de-excitation code ABLA07 are documented. The new developments of ABLA07 have been guided by the empirical knowledge obtained in a recent experimental campaign on the nuclide distributions measured at GSI, Darmstadt. Besides distinct signatures of very asymmetric binary splits, lighter systems show clear features of multifragmentation, while heavy systems reveal the influence of dynamics and microscopic structure on the fission process. ABLA07 includes elaborate but efficient descriptions of all these processes, with one set of the model parameters fixed for all systems and all energies.
Evaluation of global thermodynamic properties, such as the entropy or the free energy, of complex systems featuring a high degree of frustration or disorder is often desirable. Nevertheless, they cannot be measured directly in standard Monte Carlo simulation. Therefore, they are either evaluated indirectly from the directly measured quantities, for example by the thermodynamic integration method (TIM), or by applying more sophisticated simulation methods, such as the Wang-Landau (WL) algorithm, which can directly sample density of states. In the present investigation we compare the performance of the WL and TIM methods in terms of calculation of the entropy of an Ising antiferromagnetic system on a Kagome lattice - a typical example of a complex spin system with high geometrical frustration resulting in a non-zero residual entropy the value of which is exactly known. It is found that in terms of accuracy the implementationally simpler TIM can deliver results comparable with the more involved WL method.
The triangle anomalies in conformal field theory, which can be used to determine the central charge a, correspond to the Chern-Simons couplings of gauge fields in AdS under the gauge/gravity correspondence. We present a simple geometrical formula for the Chern-Simons couplings in the case of type IIB supergravity compactified on a five-dimensional Einstein manifold X. When X is a circle bundle over del Pezzo surfaces or a toric Sasaki-Einstein manifold, we show that the gravity result is in perfect agreement with the corresponding quiver gauge theory. Our analysis reveals an interesting connection with the condensation of giant gravitons or dibaryon operators which effectively induces a rolling among Sasaki-Einstein vacua.
Multi band photometry and light curve analysis for two newly recognized contact binary systems, TYC 6995-813-1 and NSVS 13602901 are presented. Both were found to be of extreme low mass ratios 0.11 and 0.17, respectively. The secondary components of both systems show evidence of considerable evolution with elevated densities as well as both luminosity and radii well above their main sequence counterparts. Even in the absence of significant spot activity at least one of the systems, TYC 6995-813-1, shows features of magnetic and chromospheric activity. TYC 6995-813-1 is also determined to be a potential merger candidate with its current separation near the theoretical instability separation.
Different thicknesses of cobalt thin films were growth by magnetron sputtering deposition techniques. The films thicknesses were determinated with X ray Photoelectron Spectroscopy (XPS) and Quartz Crystal Monitoring (QCM). XPS is also used to determinate the films quality. The films magnetic properties were determinated by Ferromagnetic Resonance (FMR) technique.
The illumination pattern (or emissivity profile) of the accretion disc due to the reflection of X-rays in AGN can be understood in terms of relativistic effects on the rays propagating from a source in a corona surrounding the central black hole, both on their trajectories and on the accretion disc itself. Theoretical emissivity profiles due to isotropic point sources as well as simple extended geometries are computed in general relativistic ray tracing simulations performed on graphics processing units (GPUs). Such simulations assuming only general relativity naturally explain the accretion disc emissivity profiles determined from relativistically broadened emission lines which fall off steeply (with power law indices of between 6 and 8) over the inner regions of the disc, then flattening off to almost a constant before tending to a constant power law of index 3 over the outer disc. Simulations for a variety of source locations, extents and geometries show how the emissivity profiles depend on these properties, and when combined with reverberation time lags allow the location and extent of the primary X-ray source to be constrained. Comparing the emissivity profile determined from the broadened iron K emission line in spectra of 1H 0707-495 obtained in January 2008 to theoretical emissivity profiles and applying constraints from reverberation lags suggest that there exists an extended region of primary X-ray emission located as low as 2rg above the accretion disc, extending outwards to a radius of around 30rg.
We examine the expected X-ray polarization properties of neutron-star X-ray sources of various types, e.g., accretion and rotation powered pulsars, magnetars, and low-mass X-ray binaries. We summarize the model calculations leading to these expected properties. We describe how a comparison of these with their observed properties, as inferred from GEMS data, will probe the essential dynamical, electromagnetic, plasma, and emission processes in neutron-star binaries, discriminate between models of these processes, and constrain model parameters. An exciting goal is the first observational demonstration in this context of the existence of vacuum resonance, a fundamental quantum electrodynamical phenomenon first described in the 1930s.
Comparatively simple models, with low energy structure similar to that of the MSSM, but with far fewer arbitrary parameters, can be constructed in which supersymmetry is dynamically broken at low energies. The phenomenology of these models is somewhat different than that of the usual scenario with supersymmetry broken in a hidden sector.
A detailed quantum analysis of a ionic reaction with a crucial role in the ISM is carried out to generate ab initio reactive cross sections with a quantum method. From them we obtain the corresponding CH+ depletion rates over a broad range of temperatures. The new rates are further linked to a complex chemical network that shows the evolution in time of the CH+ abundance in photodissociation region (PDR) and molecular cloud (MC) environments.   The evolutionary abundances of CH+ are given by numerical solutions of a large set of coupled, first-order kinetics equations by employing the new chemical package KROME. The differences found between all existing calculations from low-T experiments are explained via a simple numerical model that links the low-T cross section reductions to collinear approaches where nonadiabatic crossings dominate. The analysis of evolutionary abundance of CH+ reveals that the important region for the depletion reaction of this study is that above 100 K, hence showing that, at least for this reaction, the differences with the existing low-temperature experiments are of essentially no importance within the astrochemical environments. A detailed analysis of the chemical network involving CH+ also shows that a slight decrease in the initial oxygen abundance might lead to higher CH+ abundance since the main chemical carbon ion depletion channel is reduced in efficiency. This simplified observation might provide an alternative starting point to understand the problem of astrochemical models in matching the observed CH+ abundances.
Emission from active galactic nuclei (AGNs) is known to play an important role in the evolution of many galaxies including luminous and ultraluminous systems (U/LIRGs), as well as merging systems. However, the extent, duration, and exact effects of its influence are still imperfectly understood. To assess the impact of AGNs on interacting systems, we present a Spectral Energy Distribution (SED) analysis of a sample of 189 nearby galaxies. We gather and systematically re-reduce archival broad-band imaging mosaics from the ultraviolet to the far-infrared using data from GALEX, SDSS, 2MASS, IRAS, WISE, Spitzer and Herschel. We use spectroscopy from Spitzer/IRS to obtain fluxes from fine-structure lines that trace star formation and AGN activity. Utilizing the SED modelling and fitting tool CIGALE, we derive the physical conditions of the ISM, both in star-forming regions and in nuclear regions dominated by the AGN in these galaxies. We investigate how the star formation rates (SFRs) and the fractional AGN contributions ($f_{\rm{AGN}}$) depend on stellar mass, galaxy type, and merger stage. We find that luminous galaxies more massive than about $10^{10} \rm{M}_{*}$ are likely to deviate significantly from the conventional galaxy main-sequence relation. Interestingly, infrared AGN luminosity and stellar mass in this set of objects are much tighter than SFR and stellar mass. We find that buried AGNs may occupy a locus between bright starbursts and pure AGNs in the $f_{\rm{AGN}}$-[Ne V]/[Ne II] plane. We identify a modest correlation between $f_{\rm{AGN}}$ and mergers in their later stages.
We provide an algorithm for detecting the involutions leaving a surface defined by a polynomial parametrization invariant. As a consequence, the symmetry axes, symmetry planes and symmetry center of the surface, if any, can be determined directly from the parametrization, without computing or making use of the implicit representation. The algorithm is based on the fact, proven in the paper, that any involution of the surface comes from an involution of the parameter space (the real plane, in our case); therefore, by determining the latter, the former can be found. The algorithm has been implemented in the computer algebra system Maple 17. Evidence of its efficiency for moderate degrees, examples and a complexity analysis are also given.