ShantanuT01/DACTYL-Pretraining huggingface dataset:
Valley degree of freedom besides spin is a promising candidate as a carrier of information. Spintronics has come a long way and spin modulation can be realized by quantum interference and spin-orbit coupling effect. However, the control of valley degree of freedom using quantum interference is still a problem to be explored. Here we discover a mechanism of producing valley polarization in a monolayer transition metal dichalcogenides nanoribbon with attached stubs, in which valley-resolved Fano resonance are formed due to the quantum interference of intervalley backscattering. When the quantum interference occurs between the localized states at the edge of the stubs and the continuous channels in the nanoribbon, the transmission dips of Fano effect is valley-polarized. As the number of stubs increases, the valley-polarized transmission dips will split and valley-resolved minigaps are formed by Fano resonance with intervalley backscattering in stub superlattice. When the electron incident energy is in these valley-resolved gaps of the superlattice, even with several stubs, the transmission can have a significant valley polarization. Our finding points to an opportunity to realize valley functionalities by quantum interference.
Building on the results of Deligne and Illusie on liftings to truncated Witt vectors, we give a criterion for non-liftability that involves only the dimension of certain cohomology groups of vector bundles arising from the Frobenius pushforward of the de Rham complex. Using vector bundle methods, we apply this to show that exceptional Enriques surfaces, a class introduced by Ekedahl and Shepherd-Barron, do not lift to truncated Witt vectors, yet the base of the miniversal formal deformation over the Witt vectors is regular. Using the classification of Bombieri and Mumford, we also show that bielliptic surfaces arising from a quotient by an unipotent group scheme of order $p$ do not lift the ring of Witt vectors. These results hinge on some observations in homological algebra that relates splittings in derived categories to Yoneda extensions and certain diagram completions.
In this paper we consider the inverse scattering problem for the Schr{\"o}dinger operator with short-range electric potential. We prove in dimension n $\geq$ 2 that the knowledge of the scattering operator determines the electric potential and we establish H{\"o}lder-type stability in determining the short range electric potential.
Invariant mass spectra of di-electrons stemming from bremsstrahlung processes are calculated in a covariant diagrammatical approach for the exclusive reaction D p \to p_{\rm sp} n p e^+ e^- with detection of a forward spectator proton, p_{sp}. We employ an effective nucleon-meson theory for parameterizing the sub-reaction n p \to n p e^+ e^- and, within the Bethe-Salpeter formalism, derive a factorization of the cross section in the form {d\sigma_{D p \to p_{\rm sp} n p e^+ e^-}}/{dM}= {d\sigma_{n p \to n p e^+ e^-}}/{dM} \times kinematical factor related solely to the deuteron (M is the e^+ e^- invariant mass). The effective nucleon-meson interactions, including the exchange mesons \pi, \sigma, \omega and \rho as well as excitation and radiative decay of \Delta(1232), have been adjusted to the process pp \to pp e^+ e^- at energies below the vector meson production threshold. At higher energies, contributions from \omega and \rho meson excitations are analyzed in both, NN and Dp collisions. A relation to two-step models is discussed. Subthreshold di-electron production in Dp collisions at low spectator momenta is investigated as well. Calculations have been performed for kinematical conditions envisaged for forthcoming experiments at HADES.
In this note, we use a basic identity, derived from the generalized doubling integrals of \cite{C-F-G-K1}, in order to explain the existence of various global Rankin-Selberg integrals for certain $L$-functions. To derive these global integrals, we use the identities relating Eisenstein series in \cite{G-S}, together with the process of exchanging roots. We concentrate on several well known examples, and explain how to obtain them from the basic identity. Using these ideas, we also show how to derive a new global integral.
We apply the background field technique, recently developed for a general class of nonlinear symmetries, at tree level, to the Volkov-Akulov theory with spontaneously broken N=1 supersymmetry. We find that the background field expansion in terms of the free fields to the lowest order reproduces the nonlinear supersymmetry transformation rules. The double soft limit of the background field is, in agreement with the new general identities, defined by the algebra of the nonlinear symmetries.
We consider the equation $\Delta^2 u=g(x,u) \geq 0$ in the sense of distribution in $\Omega'=\Omega\setminus \{0\} $ where $u$ and $ -\Delta u\geq 0.$ Then it is known that $u$ solves $\Delta^2 u=g(x,u)+\alpha \delta_0-\beta \Delta \delta_0,$ for some non-negative constants $\alpha$ and $ \beta.$ In this paper we study the existence of singular solutions to $\Delta^2 u= a(x) f(u)+\alpha \delta_0-\beta \Delta \delta_0$ in a domain $\Omega\subset \mathbb{R}^4,$ $ a$ is a non-negative measurable function in some Lebesgue space. If $\Delta^2 u=a(x)f(u)$ in $\Omega',$ then we find the growth of the nonlinearity $f$ that determines $\alpha$ and $\beta$ to be $0.$ In case when $\alpha=\beta =0,$ we will establish regularity results when $f(t)\leq C e^{\gamma t},$ for some $C, \gamma>0.$ This paper extends the work of Soranzo (1997) where the author finds the barrier function in higher dimensions $(N\geq 5)$ with a specific weight function $a(x)=|x|^\sigma.$ Later we discuss its analogous generalization for the polyharmonic operator.
We draw a figure from where it is possible to measure the number of e-folds of expansion of the universe with a ruler. We find model independent bounds for the number of e-folds during inflation, reheating and radiation. We also give a lower bound to the size of the universe at the beginning of observable inflation. Finally, we show that consistency with a relevant diagram requires the existence of a new form of energy to drive the present expansion of the universe.
We present an algorithm for obtaining the matter content of effective six-dimensional theories resulting from compactification of F-theory on elliptic Calabi-Yau threefolds which are hypersurfaces in toric varieties. The algorithm allows us to read off the matter content of the theory from the polyhedron describing the Calabi-Yau manifold. This is based on the generalized Green-Schwarz anomaly cancellation condition.
We examine the long wave length limit of the self-consistent Hartree-Fock approximation irreducible static density-density response function by evaluating the charge induced by an external charge. Our results are consistent with the compressibility sum rule and inconsistent with earlier work that did not account for consistency between the exchange-local-field and the disorder potential. We conclude that the thermodynamic density of states is finite, in spite of the vanishing tunneling density of states at the critical energy of the integer quantum Hall transition.
We study the radiation from a collision of black holes with equal and opposite linear momenta. Results are presented from a full numerical relativity treatment and are compared with the results from a ``close-slow'' approximation. The agreement is remarkable, and suggests several insights about the generation of gravitational radiation in black hole collisions.
Sequences of Doppler images of the young, rapidly rotating late-type stars AB Dor and LQ Hya show that their equatorial angular velocity and the amplitude of their surface differential rotation vary versus time. Such variations can be modelled to obtain information on the intensity of the azimuthal magnetic stresses within stellar convection zones. We introduce a simple model in the framework of the mean-field theory and discuss briefly the results of its application to those solar-like stars.
Spin density matrices of the system, containing arbitrary even number N of indistinguishable fermions with spin S = 1/2, described by antisymmetric wave function, have been calculated. The indistinguishability and the Pauli principles are proved to determine uniquely spin states, spin correlations and entanglement of fermion spin states. Increase of the particle number in the multifermion system reduces the spin correlation in any pair of fermions. The fully entangled system of N electrons are shown to be composed by pairs with nonentangled spin states that is the incoherent superposition of the singlet and triplet states. Any large system of N fermions, such as electrons with spin S = 1/2, the spin state of any particle are shown to be entangled with the other part of the system containing N-1 particle. However, the spin state of this electron is not entangled with any other particle, and spin state of any electron pair is not entangled. These properties of spin states manifest in the Einstein-Podolsky-Rosen as confirmation or violation of the Bell inequalities indicating the presence of non-local quantum spin correlations.
We discuss the interpretation of the $ep\to ep\rho^0$ process in terms of, on the one hand, Generalized Parton Distributions and, on the other hand, an effective hadronic model based on Regge theory.
We consider a qubit that is driven along its logical $z$ axis, with noise along the $z$ axis in the driving field $\Omega$ proportional to some function $f(\Omega)$, as well as noise along the logical $x$ axis. We establish that whether or not errors due to both types of noise can be canceled out, even approximately, depends on the explicit functional form of $f(\Omega)$ by considering a power-law form, $f(\Omega)\propto\Omega^k$. In particular, we show that such cancellation is impossible for $k=0$, $1$, or any even integer. However, any other odd integer value of $k$ besides $1$ does permit cancellation; in fact, we show that both types of errors can be corrected with a sequence of four square pulses of equal duration. We provide sets of parameters that correct for errors for various rotations and evaluate the error, measured by the infidelity, for the corrected rotations versus the na\"ive rotations, i.e., the operations that, in the complete absence of noise, would produce the desired rotations (in this case a single pulse of appropriate duration and magnitude). We also consider a train of four trapezoidal pulses, which take into account the fact that there will be, in real experimental systems, a finite rise time, again providing parameters for error-corrected rotations that employ such pulse sequences. Our dynamical decoupling error correction scheme works for any qubit platform as long as the errors are quasistatic.
Quenching is a key topic in exploring the formation and evolution of galaxies. In this work, we study the quenching rate, i.e., the variation in the fraction of quenched galaxies per unit time, of the Illustris-1 simulation. By building the quenched fraction function $f(m,\rho, t)$ of each snapshot in the simulation, we derive an accurate form of quenching rate as $\Re_q=df(m,\rho,t)/dt$. According to the analytic expression of the quenching rate $\Re_q$, we split it into four components: mass quenching, environmental quenching, intrinsic mass quenching and intrinsic environmental quenching. The precise value and evolutions can be given via the formula of $\Re_q$. With this method, we analyze the Illustris-1 simulation. We find that quenched galaxies concentrate around $M_*\simeq10^{11}h^{-1}M_\odot$ and $\delta+1\simeq10^{3.5}$ at earlier times, and that the quenching galaxy population slowly shifts to lower stellar mass and lower overdensity regions with time. We also find that mass quenching dominates the quenching process in this simulation, in agreement with some previous analytical models. Intrinsic quenching is the second most important component. Environmental quenching is very weak, because it is possible that the pre- or postprocessing of environments disguises environmental quenching as intrinsic quenching. We find that our method roughly predict the actual quenching rate. It could well predict the actual amount of galaxies quenched by intrinsic quenching. However, it overestimates the amount of mass quenching galaxies and underestimates the amount of environmental quenching. We suggest that the reason is the nonlinearity of the environmental overdensity change and mass growth of the galaxy.
In this paper, we are concerned with the following prey-taxis system with fluid surrounding describing by the incompressible Navier-Stokes equations in a bounded domain with smooth boundary. We show that it has global classical solutions and give decay properties of these solutions.
The Yakutsk array dataset in the energy interval $(10^{17},10^{19})$ eV is revisited in order to interpret the zenith angle distribution of an extensive air shower event rate of ultra-high energy cosmic rays. The close relation of the distribution to the attenuation of the main measurable parameter of showers, $S_{600}$, is examined. Measured and expected distributions are used to analyze the arrival directions of cosmic rays on an equatorial map including the energy range below $10^{18}$ eV, which was previously avoided due to the reduced trigger efficiency of the array in the range. While the null hypothesis cannot be rejected with data from the Yakutsk array, an upper limit on the fraction of cosmic rays from a separable source in the uniform background is derived as a function of declination and energy.
Lupu introduced a coupling between a random walk loop-soup and a Gaussian free field, where the sign of the field is constant on each cluster of loops. This coupling is a signed version of isomorphism theorems relating the square of the GFF to the occupation field of Markovian trajectories. His construction starts with a loop-soup, and by adding additional randomness samples a GFF out of it. In this article we provide the inverse construction: starting from a signed free field and using a self-interacting random walk related to this field, we construct a random walk loop-soup. Our construction relies on the previous work by Sabot and Tarr\`es, which inverts the coupling from the square of the GFF rather than the signed GFF itself. As a consequence, we also deduce an inversion of the coupling between the random current and the FK-Ising random cluster models introduced by Lupu and Werner.
The recent LHCb discovery of states $P_c^+(4380)$, $P_c^+(4450)$, believed to be $c\bar c uud$ pentaquark resonances, begs the question of whether equivalent states with $c\bar c \to s\bar s$ exist, and how they might be produced. The precise analogue to the $P_c^+$ discovery channel $\Lambda_b \to J/\psi \, K^- \! p$, namely, $\Lambda_c \to \phi \pi^0 \! p$, is feasible for this study and indeed is less Cabibbo-suppressed, although its limited phase space suggests that evidence of a $s\bar s uud$ resonance $P_s^+$ would be confined to the kinematic endpoint region.
The $\mu$-Camassa-Holm ($\mu$CH) equation is a nonlinear integrable partial differential equation closely related to the Camassa-Holm equation. We prove that the periodic peaked traveling wave solutions (peakons) of the $\mu$CH equation are orbitally stable.
We consider the Ising spin system, which stems out from the corresponding Multiple-spin exchange (MSE) Hamiltonian, on the special one--dimensional lattice, diamond-plaquette chain. Using the technique e of transfer-matrix we obtain the exact expression for system free energy with the aid of which we obtain the magnetization function. Analyzing magnetization curves for varies values of temperature and couplin constants we found the magnetization plateaux at 1/3 and 2/3 of the full moment.   The corresponding microscopic spin configurations are unknown by virtue of high frustration.
In this work, we conduct a study on the properties of single-{\Lambda} hypernuclei in the relativistic mean-field theory with the parameter set FSU, where the isoscalar-isovector coupling has been included to soften the symmetry energy. In our model, a tensor coupling between {\omega} and {\Lambda} is employed, which is found to be essential in obtaining the small spin-orbit interaction in single-{\Lambda} hypernuclei. Our calculated values of {\Lambda} single-particle energies are in good agreement with the known experimental data. As a comparison to other existing parameter sets, calculations are also carried out by using parameterizaions such as NL3 and NL3*. The results show that the parameter set FSU is as successful as those of NL3 and NL3* in terms of reproducing the properties of single-{\Lambda} hypernuclei.
We investigate the sensitivity of the heavy ion mode of the LHC to Higgs boson and Radion production via photon-photon fusion through the analysis of the processes photon to photon photon, photon photon to b anti-b, and photon photon to g g in peripheral heavy ion collisions. We suggest cuts to improve the Higgs and Radion signal over standard model background ratio and determine the capability of LHC to detect these particles production.
Interlayer magnetoresistance (ILMR) effect is explored in a vertical stack of weakly coupled multilayer graphene as grown by chemical vapor deposition (CVD). This effect has been characterized as a function of temperature and tilt angle of the magnetic field with respect to the interlayer current. To our knowledge, this is the first experimental report on angle dependent ILMR effect in graphitic systems. Our data agrees qualitatively with the existing theories of ILMR in multilayer massless Dirac Fermion systems. However, a sharper change in ILMR has been observed as the tilt angle of the magnetic field is varied. A physical explanation of this effect is proposed, which is consistent with our experimental scenario.
We present the results of HI 21-cm line observations to explore the nature of the high-velocity (HV) HI gas at l ~ 173{\circ} . In low-resolution Hi surveys this HV gas appears as faint, wing-like, HI emission that extends to velocities beyond those allowed by Galactic rotation. We designate this feature FVW (Forbidden Velocity Wing) 172.8+1.5. Our high-resolution (3.'4) Arecibo HI observations show that FVW 172.8+1.5 is composed of knots, filaments, and ring-like structures distributed over an area a few degrees in extent. These HV HI emission features are confined within the limits of the HII complex G173+1.5, which is composed of five Sharpless HII regions distributed along a radio continuum loop of size 4{\circ}.4 {\times} 3{\circ}.4, or ~ 138 pc {\times} 107 pc, at a distance of 1.8 kpc. G173+1.5 is one of the largest star-forming regions in the outer Galaxy. We demonstrate that the HV HI gas is well correlated with the radio continuum loop and that the two seem to trace an expanding shell. The expansion velocity of the shell is large (55 km s-1) suggesting that it represents a supernova-remnant (SNR). We derive physical parameters for the shell and show these to be consistent with the object being a SNR. We also detect hot X-ray emitting gas inside the HII complex by analyzing the ROSAT all-sky X-ray background survey data. This also supports the SNR interpretation. We conclude that the HV HI gas and the X-rays are most likely the products of a supernova explosion(s) within the HII complex, possibly in a cluster that triggered the formation of these HII regions.
The solar cycle and its associated magnetic activity are the main drivers behind changes in the interplanetary environment and the Earth's upper atmosphere (commonly referred to as space weather). These changes have a direct impact on the lifetime of space-based assets and can create hazards to astronauts in space. In recent years there has been an effort to develop accurate solar cycle predictions (with aims at predicting the long-term evolution of space weather), leading to nearly a hundred widely spread predictions for the amplitude of solar cycle 24. A major contributor to the disagreement is the lack of direct long-term databases covering different components of the solar magnetic field (toroidal vs.\ poloidal). Here we use sunspot area and polar faculae measurements spanning a full century (as our toroidal and poloidal field proxies), to study solar cycle propagation, memory, and prediction. Our results substantiate predictions based on the polar magnetic fields, whereas we find sunspot area to be uncorrelated to cycle amplitude unless multiplied by area-weighted average tilt. This suggests that the joint assimilation of tilt and sunspot area is a better choice (with aims to cycle prediction) than sunspot area alone, and adds to the evidence in favor of active region emergence and decay as the main mechanism of poloidal field generation (i.e. the Babcock-Leighton mechanism). Finally, by looking at the correlation between our poloidal and toroidal proxies across multiple cycles, we find solar cycle memory to be limited to only one cycle.
Human pose forecasting is a challenging problem involving complex human body motion and posture dynamics. In cases that there are multiple people in the environment, one's motion may also be influenced by the motion and dynamic movements of others. Although there are several previous works targeting the problem of multi-person dynamic pose forecasting, they often model the entire pose sequence as time series (ignoring the underlying relationship between joints) or only output the future pose sequence of one person at a time. In this paper, we present a new method, called Social Motion Transformer (SoMoFormer), for multi-person 3D pose forecasting. Our transformer architecture uniquely models human motion input as a joint sequence rather than a time sequence, allowing us to perform attention over joints while predicting an entire future motion sequence for each joint in parallel. We show that with this problem reformulation, SoMoFormer naturally extends to multi-person scenes by using the joints of all people in a scene as input queries. Using learned embeddings to denote the type of joint, person identity, and global position, our model learns the relationships between joints and between people, attending more strongly to joints from the same or nearby people. SoMoFormer outperforms state-of-the-art methods for long-term motion prediction on the SoMoF benchmark as well as the CMU-Mocap and MuPoTS-3D datasets. Code will be made available after publication.
Internal rotation is considered to play a major role in determining the structure and dynamics of some globular clusters. We present a dynamical analysis of the photometry and three-dimensional kinematics of 47 Tuc and omega Cen, by means of a new family of self-consistent axisymmetric rotating models. The combined use of line-of-sight velocities and proper motions allows us to obtain a global description of the internal dynamical structure of the objects together with an estimate of their dynamical distances. The well-relaxed cluster 47 Tuc is very well interpreted by our dynamical models; in particular, internal rotation is found to explain the observed morphology. For the partially relaxed cluster omega Cen, the selected model provides a good representation of its complex three-dimensional kinematics, in general qualitative agreement with the observed anisotropy profile, which is characterized by tangential anisotropy in the outer parts; discrepancies are found between the observed and the expected ellipticity profile and are ascribed to the presence of a high degree of radial anisotropy in the intermediate region and to its interplay with rotation.
This is a review of cosmological models prepared for the Pont d'Oye workshop on the origin of structure in the universe. The classes of models are discussed in turn, and then some of their uses are considered.