ShantanuT01/DACTYL-Pretraining huggingface dataset:
We investigate supersymmetric QCD with gauge group SU(2) and a baryon deformation to the superpotential. The existence of an uplifted vacuum at the origin with tree level metastability is demonstrated. When this model is implemented in a direct gauge mediation scenario we therefore find gaugino masses which are comparable to sfermion masses and parameterised by an effective number of messengers 1/8. All deformations are well motivated by appealing to the electric theory and an R-symmetry. This R-symmetry is explicitly broken by the same term responsible for supersymmetry breaking. Moreover, the model does not suffer from the Landau pole problem and we find that it can be described in terms of just two scales: the weak scale and a high scale like the Planck or GUT scale. The model can be tested by searching for new particles at the TeV scale charged under the visible sector gauge group.
In the context of topcolor assisted technicolor(TC2) models, we study the production of the top-pions $\pi_{t}^{0,\pm}$ with single top quark via the processes $p\bar{p} \to t\pi_{t}^{0}+X$ and $p\bar{p} \to t\pi_{t}^{\pm}+X$, and discuss the possibility of detecting these new particles at Tevatron and LHC. We find that it is very difficult to observe the signals of these particles via these processes at Tevatron, while the neutral and charged top-pions $\pi_{t}^{0}$ and $\pi_{t}^{\pm}$ can be detecting via considering the same sign top pair $tt\bar{c}$ event and the $tt\bar{b}$ (or $t\bar{t}b$) event at LHC, respectively.
Results based on {\em ab initio} density functional calculations indicate a general graphitization tendency in ultrathin slabs of cubic diamond, boron nitride, and many other cubic structures including rocksalt. Whereas such compounds often show an energy preference for cubic rather than layered atomic arrangements in the bulk, the surface energy of layered systems is commonly lower than that of their cubic counterparts. We determine the critical slab thickness for a range of systems, below which a spontaneous conversion from a cubic to a layered graphitic structure occurs, driven by surface energy reduction in surface-dominated structures.
We introduce the notion of "separation of conditions" meaning that a description of statistical data obtained from experiments, performed under a set of different conditions, allows for a decomposition such that each partial description depends on mutually exclusive subsets of these conditions. Descriptions that allow a separation of conditions are shown to entail the basic mathematical framework of quantum theory. The Stern-Gerlach and the Einstein-Podolsky-Rosen-Bohm experiment with three, respectively nine possible outcomes are used to illustrate how the separation of conditions can be used to construct their quantum theoretical descriptions. It is shown that the mathematical structure of separated descriptions implies that, under certain restrictions, the time evolution of the data can be described by the von Neumann/Schr\"odinger equation.
The state space of a generic string bit model is spanned by $N\times N$ matrix creation operators acting on a vacuum state. Such creation operators transform in the adjoint representation of the color group $U(N)$ (or $SU(N)$ if the matrices are traceless). We consider a system of $b$ species of bosonic bits and $f$ speciesof fermionic bits. The string, emerging in the $N\to\infty$ limit, identifies $P^+=mM\sqrt{2}$ with $M$ the bit number operator and $P^-=H\sqrt{2}$ with $H$ the system Hamiltonian. We study the thermal properties of this string bit system in the case $H=0$, which can be considered the tensionless string limit: the only dynamics is restricting physical states to color singlets. Then the thermal partition function ${\rm Tr} e^{-\beta mM}$ can be identified, putting $x=e^{-\beta m}$, with a generating function $\chi_0^{bf}(x)$, for which the coefficient of $x^n$ in its expansion about $x=0$ is the number of color singlets with bit number $M=n$. This function is a purely group theoretic object, which is well-studied in the literature. We show that at $N=\infty$ this system displays a Hagedorn divergence at $x=1/(b+f)$ with ultimate temperature $T_H=m/\ln(b+f)$. The corresponding function for finite $N$ is perfectly finite for $0<x<1$, so the $N=\infty$ system exhibits a phase transition at temperature $T_H$ which is absent for any finite $N$. We demonstrate that the low temperature phase is unstable above $T_H$. The lowest-order $1/N$ asymptotic correction, for $x\to1$ in the high temperature phase, is computed for large $N$. Remarkably, this is related to the number of labeled Eulerian digraphs with $N$ nodes. Systematic methods to extend our results to higher orders in $1/N$ are described.
We analyze the consumption-portfolio selection problem of an investor facing both Brownian and jump risks. We bring new tools, in the form of orthogonal decompositions, to bear on the problem in order to determine the optimal portfolio in closed form. We show that the optimal policy is for the investor to focus on controlling his exposure to the jump risk, while exploiting differences in the Brownian risk of the asset returns that lies in the orthogonal space.
Let $X$ be an isotropic Grassmannian of type $B$, $C$, or $D$. In this paper we calculate $K$-theoretic Pieri-type triple intersection numbers for $X$: that is, the sheaf Euler characteristic of the triple intersection of two arbitrary Schubert varieties and a special Schubert variety in general position. We do this by determining explicit equations for the projected Richardson variety corresponding to the two arbitrary Schubert varieties, and show that it is a complete intersection in projective space. The $K$-theoretic Pieri coefficients are alternating sums of these triple intersection numbers, and we hope they will lead to positive Pieri formulas for isotropic Grassmannians.
The hypothesis that the rapid appearance of life on Earth justifies the belief that life is widespread in the universe has been investigated statistically by Lineweaver and Davis. However, a rapid appearance could also be interpreted as evidence for a nonterrestrial origin. I attempt to quantify the relative probabilities for a nonindigenous versus an indigenous origin of life on Earth, on the assumption that biogenesis involved one or more highly improbable steps, using a generalization of the well known observer selection argument of Carter. The analysis is specifically applied to a Martian origin of life, with subsequent transfer to Earth within impact ejecta.
At low temperatures, the main coolant in primordial gas is molecular hydrogen, H2. Recent work has shown that primordial gas that is not collapsing gravitationally but is cooling from an initially ionized state forms hydrogen deuteride, HD, in sufficient amounts to cool the gas to the temperature of the cosmic microwave background. This extra cooling can reduce the characteristic mass for gravitational fragmentation and may cause a shift in the characteristic masses of population III stars. Motivated by the importance of the atomic and molecular data for the cosmological question, we assess several chemical and radiative processes that have hitherto been neglected: the sensitivity of the low temperature H2 cooling rate to the ratio of ortho-H2 to para-H2, the uncertainty in the low temperature cooling rate of H2 excited by collisions with H, the effects of cooling from H2 excited by collisions with H+ and e-, and the large uncertainties in the rates of several of the reactions responsible for determining the H2 fraction in the gas.   We show that the most important of the neglected processes is the excitation of H2 by collisions with protons and electrons. This cools the gas more rapidly at early times, and so it forms less H2 and HD at late times. This fact, as well as several of the chemical uncertainties presented here, significantly affects the thermal evolution of the gas. We anticipate that this may lead to clear differences in future detailed 3D studies of first structure formation. Finally, we show that although the thermal evolution of the gas is in principle sensitive to the ortho-para ratio, in practice the standard assumption of a 3:1 ratio produces results that are almost indistinguishable from those produced by a more detailed treatment. (abridged)
We discuss aspects of the statistical hadronization model for the production of mesons with open and hidden charm in ultra-relativistic nuclear collisions. Emphasis is placed on what can be inferred from the dependence of the yield of charmonia on the number of participants in the collisions.
Two spherically symmetric, static Lorentzian wormholes are obtained in tetrad theory of gravitation as a solution of the equation $\rho=\rho_t=0$, where $\rho=T_{ij}u^iu^j, \rho_t=(T_{ij}-{1/2}Tg_{ij})u^iu^j$ and $u^iu_i=-1$. This equation characterizes a class of spacetime which are "self-dual" (in the sense of electrogravity duality). The obtained solutions are characterized by two-parameters $k_1, k_2$ and have a common property that they reproduce the same metric spacetime. This metric is the static Lorentzian wormhole and it includes the Schwarzschild black hole. Calculating the energy content of these tetrad fields using the {\it superpotential method given by M{\o}ller in the context of teleparallel spacetime} we find that $E=m$ or $2m$ which does not depend on the two parameters $k_1$ and $k_2$ characterize the wormhole.
We derive an identity for certain linear combinations of polylogarithm functions with negative exponents, which implies relations for linear combinations of Eulerian numbers. The coefficients of our linear combinations are related to expanding moments of Satake parameters of holomorphic cuspidal newforms in terms of the moments of the corresponding Fourier coefficients, which has applications in analyzing lower order terms in the behavior of zeros of L-functions near the central point.
We analyse the most general connection allowed by Einstein-Hilbert theory in Palatini formalism. We also consider a matter lagrangian independent of the affine connection. We show that any solution of the equation of the connection is essentially Levi-Civita up to a term that contains an undetermined 1-form. Finally, it is proved that these connections and Levi-Civita describe a completely equivalent physics.
We present a model independent analysis of custodial corrections to the $S$ parameter. The negative contributions coming from direct corrections, i.e. the corrections associated to effects of new physics in the fermionic sector, can be used to eliminate unwanted positive oblique contributions to $S$. By means of such an ideal cancellation among oblique and direct corrections the electroweak physics can be made insensitive to custodial new physics. The Lagrangian analysis of the ideal cancellation reveals a possible sizable redefinition of the effective electroweak energy scale with respect to models with only oblique corrections. We then infer from general principles the full expression for the effective custodial operator responsible in the gauge sector for the contribution to $S$. We show that the ideal cancellation exactly eliminates all the custodial corrections, including those in the non-abelian and longitudinal terms. Indeed, provided redefinitions of the physical parameters, the standard model Lagrangian can be equivalently defined modulo custodial corrections in the gauge and fermionic sectors. Thus the ideal cancellation can be regarded as an effective symmetry. Finally we investigate the theoretical origin of this effective symmetry in terms of the effective gauge structure induced by custodial new physics.
We extend some results about F\"ollmer's pathwise It\^o calculus that have only been derived for continuous paths to c\`adl\`ag paths with quadratic variation. We study some fundamental properties of pathwise It\^o integrals with respect to c\`adl\`ag integrators, especially associativity and the integration by parts formula. Moreover, we study integral equations with respect to pathwise It\^o integrals. We prove that some classes of integral equations, which can be explicitly solved in the usual stochastic calculus, can also be solved within the framework of F\"ollmer's calculus.
We present abstract inhomogeneous Strichartz estimates for dispersive operators, extending previous work by M. Keel and T. Tao on the one hand, and generalising results of D. Foschi, M. Vilela, M. Nakamura and T. Ozawa on the other hand. It is shown that these abstract estimates imply new inhomogeneous Strichartz estimates for the wave equation and some Schr\"odinger equations involving potentials.
The ongoing experimental and theoretical effort aimed at understanding non-classical rotational inertia in solid helium, has sparked renewed interest in the supersolid phase of matter, its microscopic origin and character, and its experimental detection. The purpose of this colloquium is a) to provide a general theoretical framework for the phenomenon of supersolidity and b) to review some of the experimental evidence for solid Helium-four, and discuss its possible interpretation in terms of physical effects underlain by extended defects (such as dislocations). We provide quantitative support to our theoretical scenarios by means of first principle numerical simulations. We also discuss alternate avenues for the observation of the supersolid phase, not involving helium but rather assemblies of ultracold atoms.
We investigate by means of Monte Carlo simulations the dynamic phase transition of the two-dimensional kinetic Blume-Capel model under a periodically oscillating magnetic field in the presence of a quenched random crystal-field coupling. We analyze the universality principles of this dynamic transition for various values of the crystal-field coupling at the originally second-order regime of the corresponding equilibrium phase diagram of the model. A detailed finite-size scaling analysis indicates that the observed nonequilibrium phase transition belongs to the universality class of the equilibrium Ising ferromagnet with additional logarithmic corrections in the scaling behavior of the heat capacity. Our results are in agreement with earlier works on kinetic Ising models.
We present the results of particle-in-cell numerical pair plasma simulations of relativistic 2D magnetostatic equilibria known as the 'ABC' fields. In particular, we focus on the lowest-order unstable configuration consisting of two minima and two maxima of the magnetic vector potential. Breaking of the initial symmetry leads to exponential growth of the electric energy and to the formation of two current layers, which is consistent with the picture of 'X-point collapse' first described by Syrovatskii. Magnetic reconnection within the layers heats a fraction of particles to very high energies. After the saturation of the linear instability, the current layers are disrupted and the system evolves chaotically, diffusing the particle energies in a stochastic second-order Fermi process leading to the formation of power-law energy distributions. The power-law slopes harden with the increasing mean magnetization, but they are significantly softer than those produced in simulations initiated from Harris-type layers. The maximum particle energy is proportional to the mean magnetization, which is attributed partly to the increase of the effective electric field and partly to the increase of the acceleration time scale. We describe in detail the evolving structure of the dynamical current layers, and report on the conservation of magnetic helicity. These results can be applied to highly magnetized astrophysical environments, where ideal plasma instabilities trigger rapid magnetic dissipation with efficient particle acceleration and flares of high-energy radiation.
Conversion of Si to a direct bandgap semiconductor for optoelectronic application is a great challenge for many decades. It is proposed that embedment of suitable sized quantum dots into silicon matrix may be exploited to convert silicon to a direct bandgap semiconductor. The other bottleneck to this outstanding issue is the identification of local excitons, a signature of direct bandgap property and their comportment within the dots that can be utilized in engineering optoelectronic devices, quantum communications, etc. We studied the core level spectra of Si/Ge quantum huts embedded Si employing high resolution photoemission spectroscopy. Inverted quantum huts (IQHs) of Ge (13.3nm x 6.6nm) were grown on a Si buffer layer deposited on Si(001) surface using molecular beam epitaxy method and the photoemission experiments were carried out at different locations of the IQH structures exposed via controlled sputtering and annealing processes. We discover distinct features in the Ge 3$d$ core level spectra at the lower binging energy side of the bulk 3$d$ peak in contrast to the scenario of core level satellites often observed due to photoemission final state effects. The energy of these features are found to be sensitive to the location of the IQH structure probed revealing different core hole screening by the excitons located at different parts of IQHs. These results reveal local character of the excitons in the IQHs necessary for type I photoluminescence and establish core level spectroscopy as a direct probe of local excitons. These finding are expected to help amalgamation of microelectronics and solid state photonics important for optoelectronic applications.
Most detected neutral atomic hydrogen (HI) at low redshift is associated with optically bright galaxies. However, a handful of HI clouds are known which appear to be optically dark and have no nearby potential progenitor galaxies, making tidal debris an unlikely explanation. In particular, 6 clouds identified by the Arecibo Galaxy Environment Survey are interesting due to the combination of their small size, isolation, and especially their broad line widths atypical of other such clouds. A recent suggestion is that these clouds exist in pressure equilibrium with the intracluster medium, with the line width arising from turbulent internal motions. Here we explore that possibility by using the FLASH code to perform a series of 3D hydro simulations. Our clouds are modelled using spherical Gaussian density profiles, embedded in a hot, low-density gas representing the intracluster medium. The simulations account for heating and cooling of the gas, and we vary the structure and strength of their internal motions. We create synthetic HI spectra, and find that none of our simulations reproduce the observed cloud parameters for longer than about 100 Myr : the clouds either collapse, disperse, or experience rapid heating which would cause ionisation and render them undetectable to HI surveys. While the turbulent motions required to explain the high line widths generate structures which appear to be inherently unstable, making this an unlikely explanation for the observed clouds, these simulations demonstrate the importance of including the intracluster medium in any model seeking to explain the existence of these objects.
We present a test to quantify how well some approximate methods, designed to reproduce the mildly non-linear evolution of perturbations, are able to reproduce the clustering of DM halos once the grouping of particles into halos is defined and kept fixed. The following methods have been considered: Lagrangian Perturbation Theory (LPT) up to third order, Truncated LPT, Augmented LPT, MUSCLE and COLA. The test runs as follows: halos are defined by applying a friends-of-friends (FoF) halo finder to the output of an N-body simulation. The approximate methods are then applied to the same initial conditions of the simulation, producing for all particles displacements from their starting position and velocities. The position and velocity of each halo are computed by averaging over the particles that belong to that halo, according to the FoF halo finder. This procedure allows us to perform a well-posed test of how clustering of the matter density and halo density fields are recovered, without asking to the approximate method an accurate reconstruction of halos. We have considered the results at $z=0,0.5,1$, and we have analysed power spectrum in real and redshift space, object-by-object difference in position and velocity, density Probability Distribution Function (PDF) and its moments, phase difference of Fourier modes. We find that higher LPT orders are generally able to better reproduce the clustering of halos, while little or no improvement is found for the matter density field when going to 2LPT and 3LPT. Augmentation provides some improvement when coupled with 2LPT, while its effect is limited when coupled with 3LPT. Little improvement is brought by MUSCLE with respect to Augmentation. The more expensive particle-mesh code COLA outperforms all LPT methods [abridged]
The Lyon-Meudon Extragalactic database (LEDA) gives a free access to the main astrophysical parameters for more than 100,000 galaxies. The most common names are compiled allowing users to recover quickly any galaxy. All these measured astrophysical parameters are first reduced to a common system according to well defined reduction formulae leading to mean homogeneized parameters. Further, these parameters are also transformed into corrected parameters from widely accepted models. For instance, raw 21-cm line widths are transformed into mean standard widths after correction for instrumental effect and then into maximum velocity rotation properly corrected for inclination and non-circular velocity. This paper presents the reduction formulae for each parameter: coordinates, morphological type and luminosity class, diameter and axis ratio, apparent magnitude (UBV, IR, HI) and colors, maximum velocity rotation and central velocity dispersion, radial velocity, mean surface brightness, distance modulus and absolute magnitude, and group membership. For each of these parameters intermediate quantities are given: galactic extinction, inclination, K-correction etc..   All these parameters are available from direct connexion to LEDA (telnet lmc.univ-lyon1.fr, login: leda, no passwd   OR http://www-obs.univ-lyon1.fr/leda ) and distributed on a standard CD-ROM (PGC-ROM 1996) by the Observatoire de Lyon via the CNRS (mail to petit@obs.univ-lyon1.fr).
The twist--2 contributions to the polarized structure functions in deep inelastic lepton--hadron scattering are calculated including the exchange of weak bosons and using both the operator product expansion and the covariant parton model. A new relation between two structure functions leading to a sequence of new sum rules is found. The light quark mass corrections to the structure functions are derived in lowest order QCD.
Fiol, Garriga, and Yebra introduced the notion of pseudo-distance-regular vertices, which they used to develop a new characterization of distance-regular graphs. Building on that work, Fiol and Garriga developed the spectral excess theorem for distance-regular graphs. We extend both these characterizations to distancebiregular graphs and show how these characterizations can be used to study bipartite graphs with distance-regular halved graphs and graphs with the spectrum of a distance-biregular graph.
Both ``phason'' elastic constants have been measured from Monte Carlo simulations of a random-tiling icosahedral quasicrystal model with a Hamiltonian. The low-temperature limit approximates the ``canonical-cell'' tiling used to describe several real quasicrystals. The elastic constant K2 changes sign from positive to negative with decreasing temperature; in the ``canonical-cell'' limit, K2/K1 appears to approach -0.7, about the critical value for a phason-mode modulation instability. We compare to the experiments on i-AlPdMn and i-AlCuFe.