ShantanuT01/DACTYL-Pretraining huggingface dataset:
We study the effect of backward scatterings in the tunneling at a point contact between the edges of a second level hierarchical fractional quantum Hall states. A universal scaling dimension of the tunneling conductance is obtained only when both of the edge channels propagate in the same direction. It is shown that the quasiparticle tunneling picture and the electron tunneling picture give different scaling behaviors of the conductances, which indicates the existence of a crossover between the two pictures. When the direction of two edge-channels are opposite, e.g. in the case of MacDonald's edge construction for the $\nu=2/3$ state, the phase diagram is divided into two domains giving different temperature dependence of the conductance.
We present observations of the Eridanus supergroup obtained with the Australian Square Kilometre Array Pathfinder (ASKAP) as part of the pre-pilot survey for the Widefield ASKAP L-band Legacy All-sky Blind Survey (WALLABY). The total number of detected HI sources is 55, of which 12 are background galaxies not associated with the Eridanus supergroup. Two massive HI clouds are identified and large HI debris fields are seen in the NGC 1359 interacting galaxy pair, and the face-on spiral galaxy NGC 1385. We describe the data products from the source finding algorithm and present the basic parameters. The presence of distorted HI morphology in all detected galaxies suggests ongoing tidal interactions within the subgroups. The Eridanus group has a large fraction of HI deficient galaxies as compared to previously studied galaxy groups. These HI deficient galaxies are not found at the centre of the group. We find that galaxies in the Eridanus supergroup do not follow the general trend of the atomic gas fraction versus stellar mass scaling relation, which indicates that the scaling relation changes with environmental density. In general, the majority of these galaxies are actively forming stars.
Using the Grad-Shafranov equation, we consider a new analytical model of the black hole magnetosphere based on the assumption that the magnetic field is radial near the horizon and uniform (cylindrical) in the jet region. Within this model, we have managed to show that the angular velocity of particles near the rotation axis of the black hole can be smaller than one half of the black hole angular velocity. This result is consistent with the latest numerical simulations.
The helioseismic observations of the internal rotation profile of the Sun raise questions about the two-dimensional (2D) nature of the transport of angular momentum in stars. Here we derive a convective prescription for axisymmetric (2D) stellar evolution models. We describe the small scale motions by a spectrum of unstable linear modes in a Boussinesq fluid. Our saturation prescription makes use of the angular dependence of the linear dispersion relation to estimate the anisotropy of convective velocities. We are then able to provide closed form expressions for the thermal and angular momentum fluxes with only one free parameter, the mixing length.   We illustrate our prescription for slow rotation, to first order in the rotation rate. In this limit, the thermodynamical variables are spherically symetric, while the angular momentum depends both on radius and latitude. We obtain a closed set of equations for stellar evolution, with a self-consistent description for the transport of angular momentum in convective regions. We derive the linear coefficients which link the angular momentum flux to the rotation rate ($\Lambda$- effect) and its gradient ($\alpha$-effect). We compare our results to former relevant numerical work.
We use the GALFORM semi-analytical model of galaxy formation and the Planck-Millennium simulation to investigate the origins of stellar mass in galaxies and their spheroids. We compare the importance of mergers and disc instabilities, as well as the starbursts that they trigger. We find that the fraction of galaxy stellar mass formed \textit{ex situ} ($f_\mathrm{ex}$) increases sharply from $M_*=10^{11}$ M$_\odot$ upwards, reaching $80\%$ at $M_*=10^{11.3}$ M$_\odot$. For low-mass galaxies we find larger \textit{\textit{ex situ}} contributions at $z=0$ than in other models ($7$-$12\%$), with a decrease towards higher redshifts. The global \textit{ex situ} fraction of all stellar mass falls sharply with redshift, from $40\%$ at $z=0$ to $3\%$ at $z=10$. Major mergers contribute roughly half of the \textit{ex situ} mass, with minor mergers and smooth accretion of satellites both accounting for $\approx25\%$, almost independent of stellar mass and redshift. Mergers dominate in building up high-mass ($M_\mathrm{*,sph}>10^{11}$ M$_\odot$) and low-mass ($M_\mathrm{*,sph}<10^{8.5}$ M$_\odot$) spheroids. Disc instabilities and their associated starbursts dominate for intermediate-mass spheroids ($10^{8.5}<M_\mathrm{*,sph}<10^{11}$ M$_\odot$) at $z=0$. The mass regime where pseudobulges dominate is in agreement with observed pseudobulge fractions, but the peak value in the pseudobulge fraction predicted by GALFORM is likely too high. The total contributions of disc instabilities and their starbursts are roughly equal at $z=0$, with the former dominating for lower-mass spheroids (peak at $M_\mathrm{*,sph}=10^{9.5}$ M$_\odot$) and the latter for higher-mass ones (peak at $M_\mathrm{*,sph}=10^{10.5}$ M$_\odot$).
Epitaxial layers of the topological insulator Bi2Se3 have been grown by molecular beam epitaxy on laterally lattice-matched InP(111)B substrates. High resolution X-ray diffraction shows a significant improvement of Bi2Se3 crystal quality compared to layers deposited on other substrates. The measured full width at half maximum of the rocking curve is Delta omega=13 arcsec, and the (omega-2theta) scans exhibit clear layer thickness fringes. Atomic force microscope images show triangular twin domains with sizes increasing with layer thickness. The structural quality of the domains is confirmed on the microscopic level by transmission electron microscopy.
In the recent works [arXiv:1803.05809],[arXiv: 1806.01842], Halohedron emerged as amplituhedron for 1-loop planar diagrams in bi-adjoint massless $\phi^3$ theory. Halohedron is a specific case of graph cubeahedron where the considered graph is a cycle-graph. In [arXiv: 1906.06861],[arXiv: 1501.07152], the authors provide construction of any graph cubeahedron and we use this construction to find the polytopal realization of Halohedron. We show that the Halohedron we obtain is equivalent to the proposed realization of Halohedron in `Big Kinematic Space'[arXiv: 1806.01842].
We present the time-resolved spectral analysis of the XMM-Newton data of NGC 1365, collected during one XMM-Newton observation, which caught this "changing-look" AGN in a high flux state characterized also by a low column density ($N_{\mathrm{H}}\sim 10^{22}$ cm $^{-2}$) of the X-ray absorber. During this observation the low energy photoelectric cut-off is at about $\sim 1$ keV and the primary continuum can be investigated with the XMM-Newton-RGS data, which show strong spectral variability that can be explained as a variable low $N_{\mathrm{H}}$, which decreased from $N_{\mathrm{H}} \sim10^{23}$ cm $^{-2}$ to $10^{22}$ cm $^{-2}$ in a 100 ks time-scale. The spectral analysis of the last segment of the observation revealed the presence of several absorption features that can be associated with an ionized (log $\xi \sim 2$ erg cm s$^{-1}$) outflowing wind ($v_{\mathrm{out}} \sim 2000$ km s$^{-1}$). We detected for the first time a possible P-Cygni profile of the Mg\,\textsc{xii} Ly$\alpha$ line associated with this mildly ionized absorber indicative of a wide angle outflowing wind. We suggest that this wind is a low ionization zone of the highly ionized wind present in NGC 1365, which is responsible for the iron K absorption lines and is located within the variable X-ray absorber. At the end of the observation, we detected a strong absorption line at $E\sim 0.76$ keV most likely associated with a lower ionization zone of the absorber (log $\xi \sim 0.2$ erg cm s$^{-1}$, $N_{\mathrm{H}} \sim 10^{22}$ cm $^{-2}$), which suggests that the variable absorber in NGC 1365 could be a low ionization zone of the disk wind.
Magnetic insulators are important materials for a range of next generation memory and spintronic applications. Structural constraints in this class of devices generally require a clean heterointerface that allows effective magnetic coupling between the insulating layer and the conducting layer. However, there are relatively few examples of magnetic insulators which can be synthesized with surface qualities that would allow these smooth interfaces and precisely tuned interfacial magnetic exchange coupling which might be applicable at room temperature. In this work, we demonstrate an example of how the configurational complexity in the magnetic insulator layer can be used to realize these properties. The entropy-assisted synthesis is used to create single crystal (Mg0.2Ni0.2Fe0.2Co0.2Cu0.2)Fe2O4 films on substrates spanning a range of strain states. These films show smooth surfaces, high resistivity, and strong magnetic responses at room temperature. Local and global magnetic measurements further demonstrate how strain can be used to manipulate magnetic texture and anisotropy. These findings provide insight into how precise magnetic responses can be designed using compositionally complex materials that may find application in next generation magnetic devices.
Precise arrays of sub-100 nm diameter nanodots are fabricated from magnetic oxide perovskites with the total coverage area up to 5 mm2. Epitaxial single crystal structure of the nanodots is demonstrated by cross-sectional TEM. Low temperature MFM study confirmed the ferromagnetism of the produced particles.
A basic analysis is provided for the differential cross section characterizing Aharonov--Bohm effect with non standard (non regular) boundary conditions imposed on a wave function at the potential barrier. If compared with the standard case two new features can occur: a violation of rotational symmetry and a more significant backward scattering.
This thesis consists of three parts. In the first part, we study $\mathbb{L}^p$ solutions of a large class of BSDEs. Existence, comparison theorem, uniqueness and a stability result are proved. In the second part, we establish the solvability of quadratic semimartingale BSDEs. In contrast to current literature, we use Lipschitz-quadratic regularization and obtain the existence and uniqueness results with minimal assumptions. The third part is a brief summary of quadratic semimartingales and the monotone stability result. This provides an alternative proof of monotone stability result for quadratic semimartingales BSDEs.
We deal with the following question of Dolgachev : is the Cremona group generated by involutions ? Answer is yes in dimension $2$ (Cerveau-Deserti). We give an upper bound of the minimal number $\mathfrak{n}_\varphi$ of involutions we need to write a birational self map $\varphi$ of $\mathbb{P}^2_\mathbb{C}$.   We prove that de Jonqui\`eres maps of $\mathbb{P}^3_\mathbb{C}$ and maps of small bidegree of $\mathbb{P}^3_\mathbb{C}$ can be written as a composition of involutions of $\mathbb{P}^3_\mathbb{C}$ and give an upper bound of $\mathfrak{n}_\varphi$ for such maps $\varphi$. We get similar results in particular for automorphisms of $(\mathbb{P}^1_\mathbb{C})^n$, automorphisms of $\mathbb{P}^n_\mathbb{C}$, tame automorphisms of $\mathbb{C}^n$, monomial maps of $\mathbb{P}^n_\mathbb{C}$, and elements of the subgroup generated by the standard involution of $\mathbb{P}^n_\mathbb{C}$ and $\mathrm{PGL}(n+1,\mathbb{C})$.
Even though Generative Adversarial Networks (GANs) have shown a remarkable ability to generate high-quality images, GANs do not always guarantee the generation of photorealistic images. Occasionally, they generate images that have defective or unnatural objects, which are referred to as 'artifacts'. Research to investigate why these artifacts emerge and how they can be detected and removed has yet to be sufficiently carried out. To analyze this, we first hypothesize that rarely activated neurons and frequently activated neurons have different purposes and responsibilities for the progress of generating images. In this study, by analyzing the statistics and the roles for those neurons, we empirically show that rarely activated neurons are related to the failure results of making diverse objects and inducing artifacts. In addition, we suggest a correction method, called 'Sequential Ablation', to repair the defective part of the generated images without high computational cost and manual efforts.
We study the ground-state entanglement Hamiltonian for an interval of $N$ sites in a free-fermion chain with arbitrary filling. By relating it to a commuting operator, we find explicit expressions for its matrix elements in the large-$N$ limit. The results agree with numerical calculations and show that deviations from the conformal prediction persist even for large systems.
X-ray absorption spectra in a wide energy range around the 4d-4f excitation threshold of Gd were recorded by total electron yield from in-plane magnetized Gd metal films. Matching the experimental spectra to tabulated absorption data reveals unprecedented short light absorption lengths down to 3 nm. The associated real parts of the refractive index for circularly polarized light propagating parallel or antiparallel to the Gd magnetization, determined through the Kramers-Kronig transformation, correspond to a magneto-optical Faraday rotation of 0.7 degrees per atomic layer. This finding shall allow the study of magnetic structure and magnetization dynamics of lanthanide elements in nanosize systems and dilute alloys.
We study the mechanisms of slip transfer at a grain boundary, in titanium, using Differential Aperture X-ray Laue Micro-diffraction (DAXM). This 3D characterization tool enables measurement of the full (9-component) Nye lattice curvature tensor and calculation of the density of geometrically necessary dislocations (GNDs). We observe dislocation pile-ups at a grain boundary, as the neighbor grain prohibits easy passage for dislocation transmission. This incompatibility results in local micro-plasticity within the slipping grain, near to where the slip planes intersect the grain boundary, and we observe bands of GNDs lying near the grain boundary. We observe that the distribution of GNDs can be significantly influenced by the formation of grain boundary ledges that serve as secondary dislocation sources. This observation highlights the non-continuum nature of polycrystal deformation and helps us understand the higher order complexity of grain boundary characteristics.
Motivated by classical results of Aubry, Davenport and Cassels, we define the notion of a Euclidean quadratic form over a normed integral domain and an ADC form over an integral domain. The aforementioned classical results generalize to: Euclidean forms are ADC forms. We then initiate the study and classification of these two classes of quadratic forms, especially over discrete valuation rings and Hasse domains.
We attempt to describe the rapidity distribution of P, P-bar, K+ and K- for the most central Au+Au collisions at root(sNN) of 62.4 GeV,130 GeV and 200 GeV. The transverse momentum spectra of strange as well as non-strange hadrons e.g. P, P-bar, K+, K-, Lambda, Lambda-bar, Cascade,Cascade-bar and (Omega + Omega-bar) are studied for the whole centrality classes at all the three RHIC energies. The experimental data of the transverse momentum spectra and the rapidity distributions are well reproduced. This is done by using a statistical thermal freeze-out model which incorporates the rapidity (collision) axis as well as transverse direction boosts developed within an expanding hot and dense hadronic fluid (fireball) till the final freeze-out. We determine the thermo-chemical freeze-out conditions particularly in terms of temperature, baryon chemical potential and collective flow effect parameters for different particle species. The parameters indicate occurrence of freeze-out of the singly and doubly strange hyperon species at somewhat earlier times during the evolution of the fireball. Dependence of the freeze-out parameters on the degree of centrality is also described and it is found that the kinetic temperature increases and collective flow effect decreases with decreasing centrality at all energies studied. The nuclear transparency effect is also studied and it is clear from our model that the nuclear matter becomes more transparent at the highest RHIC energy compared to lower RHIC energies. The contribution of heavier hadronic resonance decay is taken into account.
In this paper we look at the pinning of a directed polymer by a one-dimensional linear interface carrying random charges. There are two phases, localized and delocalized, depending on the inverse temperature and on the disorder bias. Using quenched and annealed large deviation principles for the empirical process of words drawn from a random letter sequence according to a random renewal process [Birkner, Greven and den Hollander, Probab. Theory Related Fields 148 (2010) 403-456], we derive variational formulas for the quenched, respectively, annealed critical curve separating the two phases. These variational formulas are used to obtain a necessary and sufficient criterion, stated in terms of relative entropies, for the two critical curves to be different at a given inverse temperature, a property referred to as relevance of the disorder. This criterion in turn is used to show that the regimes of relevant and irrelevant disorder are separated by a unique inverse critical temperature. Subsequently, upper and lower bounds are derived for the inverse critical temperature, from which sufficient conditions under which it is strictly positive, respectively, finite are obtained. The former condition is believed to be necessary as well, a problem that we will address in a forthcoming paper. Random pinning has been studied extensively in the literature. The present paper opens up a window with a variational view. Our variational formulas for the quenched and the annealed critical curve are new and provide valuable insight into the nature of the phase transition. Our results on the inverse critical temperature drawn from these variational formulas are not new, but they offer an alternative approach, that is, flexible enough to be extended to other models of random polymers with disorder.
Until today, the small size of magnetic elements in quiet Sun areas has required the application of indirect methods, such as the line-ratio technique or multi-component inversions, to infer their physical properties. A consistent match to the observed Stokes profiles could only be obtained by introducing a magnetic filling factor that specifies the fraction of the observed pixel filled with magnetic field. Here, we investigate the properties of a small magnetic patch in the quiet Sun observed with the IMaX magnetograph on board the balloon-borne telescope Sunrise with unprecedented spatial resolution and low instrumental stray light. We apply an inversion technique based on the numerical solution of the radiative transfer equation to retrieve the temperature stratification and the field strength in the magnetic patch. The observations can be well reproduced with a one-component, fully magnetized atmosphere with a field strength exceeding 1 kG and a significantly enhanced temperature in the mid- to upper photosphere with respect to its surroundings, consistent with semi-empirical flux tube models for plage regions. We therefore conclude that, within the framework of a simple atmospheric model, the IMaX measurements resolve the observed quiet-Sun flux tube.
Interaction-free measurements introduced by Elitzur and Vaidman [Found. Phys. 23, 987 (1993)] allow finding infinitely fragile objects without destroying them. Many experiments have been successfully performed showing that indeed, the original scheme and its modifications lead to reduction of the disturbance of the observed systems. However, there is a controversy about the validity of the term ``interaction-free'' for these experiments. Broad variety of such experiments are reviewed and the meaning of the interaction-free measurements is clarified.
Magnetic properties of the spin-1/2 XXZ Heisenberg cuboctahedron are examined using exact numerical diagonalization depending on a relative strength of the exchange anisotropy. While the Ising cuboctahedron exhibits in a low-temperature magnetization curve only one-third magnetization plateau, the XXZ Heisenberg cuboctahedron displays another four intermediate plateaux at zero, one-sixth, one-half and two-thirds of the saturation magnetization. The novel magnetization plateaux generally extend over a wider range of magnetic fields with increasing of a quantum ($xy$) part of the XXZ exchange interaction. It is shown that the XXZ Heisenberg cuboctahedron exhibits in a vicinity of all magnetization jumps anomalous thermodynamic behavior accompanied with an enhanced magnetocaloric effect.
Let $\varepsilon > 0$. We prove that there are constants $m_0=m_0(\varepsilon)$ and $\kappa=\kappa(\varepsilon) > 0$ for which the following holds: For every integer $m > m_0$ and every nontrivial Dirichlet character modulo $m$, there are more than $m^{\kappa}$ primes $\ell \le m^{\frac{1}{4\sqrt{e}}+\varepsilon}$ with $\chi(\ell)\notin \{0,1\}$. The proof uses the fundamental lemma of the sieve, Norton's refinement of the Burgess bounds, and a result of Tenenbaum on the distribution of smooth numbers satisfying a coprimality condition. For quadratic characters, we demonstrate a somewhat weaker lower bound on the number of primes $\ell \le m^{\frac14+\epsilon}$ with $\chi(\ell)=1$.
We prove an algebraic property of the elements defining Hecke operators on period polynomials associated with modular forms, which implies that the pairing on period polynomials corresponding to the Petersson scalar product of modular forms is Hecke equivariant. As a consequence of this proof, we derive two indefinite theta series identities which can be seen as analogues of Jacobi's formula for the theta series associated with the sum of four squares.
The cold molecular gas in contemporary galaxies is structured in discrete cloud complexes. These giant molecular clouds (GMCs), with $10^4$-$10^7$ solar masses and radii of 5-100 parsecs, are the seeds of star formation. Highlighting the molecular gas structure at such small scales in distant galaxies is observationally challenging. Only a handful of molecular clouds were reported in two extreme submillimetre galaxies at high redshift. Here we search for GMCs in a typical Milky Way progenitor at z = 1.036. Using the Atacama Large Millimeter/submillimeter Array (ALMA), we mapped the CO(4-3) emission of this gravitationally lensed galaxy at high resolution, reading down to 30 parsecs, which is comparable to the resolution of CO observations of nearby galaxies. We identify 17 molecular clouds, characterized by masses, surface densities and supersonic turbulence all of which are 10-100 times higher than present-day analogues. These properties question the universality of GMCs and suggest that GMCs inherit their properties from ambient interstellar medium. The measured cloud gas masses are similar to the masses of stellar clumps seen in the galaxy in comparable numbers. This corroborates the formation of molecular clouds by fragmentation of distant turbulent galactic gas disks, which then turn into stellar clumps ubiquitously observed in galaxies at cosmic noon.
We show that the Torelli group of a closed surface of genus $\ge 3$ acts nontrivially on the rational cohomology of its space of $3$-element subsets.