Probing chiral interactions up to next-to-next-to-next-to-leading order in medium-mass nuclei

We study ground-state energies and charge radii of closed-shell medium-mass nuclei based on novel chiral nucleon-nucleon (NN) and three-nucleon (3N) interactions, with a focus on exploring the connections between finite nuclei and nuclear matter. To this end, we perform in-medium similarity renormalization group (IM-SRG) calculations based on chiral interactions at next-to-leading order (NLO), N$^2$LO, and N$^3$LO, where the 3N interactions at N$^2$LO and N$^3$LO are fit to the empirical saturation point of nuclear matter and to the triton binding energy. Our results for energies and radii at N$^2$LO and N$^3$LO overlap within uncertainties, and the cutoff variation of the interactions is within the EFT uncertainty band. We find underbound ground-state energies, as expected from the comparison to the empirical saturation point. The radii are systematically too large, but the agreement with experiment is better. We further explore variations of the 3N couplings to test their sensitivity in nuclei. While nuclear matter at saturation density is quite sensitive to the 3N couplings, we find a considerably weaker dependence in medium-mass nuclei. In addition, we explore a consistent momentum-space SRG evolution of these NN and 3N interactions, exhibiting improved many-body convergence. For the SRG-evolved interactions, the sensitivity to the 3N couplings is found to be stronger in medium-mass nuclei.Comment: 10 pages, 11 figures, published versio

The Origin of Chiral Anomaly and the Noncommutative Geometry

We describe the scalar and spinor fields on noncommutative sphere starting from canonical realizations of the enveloping algebra ${\cal A}={\cal U}{u(2))}$. The gauge extension of a free spinor model, the Schwinger model on a noncommutative sphere, is defined and the model is quantized. The noncommutative version of the model contains only a finite number of dynamical modes and is non-perturbatively UV-regular. An exact expresion for the chiral anomaly is found. In the commutative limit the standard formula is recovered.Comment: 30 page

Interpretation of runaway electron synchrotron and bremsstrahlung images

The crescent spot shape observed in DIII-D runaway electron synchrotron radiation images is shown to result from the high degree of anisotropy in the emitted radiation, the finite spectral range of the camera and the distribution of runaways. The finite spectral camera range is found to be particularly important, as the radiation from the high-field side can be stronger by a factor $10^6$ than the radiation from the low-field side in DIII-D. By combining a kinetic model of the runaway dynamics with a synthetic synchrotron diagnostic we see that physical processes not described by the kinetic model (such as radial transport) are likely to be limiting the energy of the runaways. We show that a population of runaways with lower dominant energies and larger pitch-angles than those predicted by the kinetic model provide a better match to the synchrotron measurements. Using a new synthetic bremsstrahlung diagnostic we also simulate the view of the Gamma Ray Imager (GRI) diagnostic used at DIII-D to resolve the spatial distribution of runaway-generated bremsstrahlung.Comment: 21 pages, 11 figure

Extreme H isotopic anomalies in chondritic organic matter

Extract from introduction: We have conducted ionprobe (IMS6f and NanoSIMS) imaging studies of various samples for H, D, C, 14N and 15N. These will ultimately be correlated with micro-analytic techniques such as FIB/TEM or STXM/XANES. We analyzed matrix fragments from Bells (CM2), Al Rais (CR2) and Tagish Lake (unique) [2], high purity insoluble organic matter (IOM) [3] extracted from EET92042 (“EET”, CR2), Bells, Murchison (CM2), Allende (CV3), Krymka (LL3.1) and, for comparison, 3 IDPs

Were Presolar Grains Destroyed by the Nebular Process Responsible for the Volatile Element Fractionation?

We present SiC abundances from a number of CM and CR chondrites using NanoSIMS raster ion imaging of acid residues. We find higher SiC abundances for CRs than previously estimated based on noble gases

Dirac equation for membranes

Dirac's idea of taking the square root of constraints is applied to the case of extended objects concentrating on membranes in D=4 space-time dimensions. The resulting equation is Lorentz invariant and predicts an infinite hierarchy of positive and negative masses (tension). There are no tachyonic solutions.Comment: 5 pages, 1 figure, v2: improved version, accepted for publication as a Brief Report in Physical Review

Structure Constants for New Infinite-Dimensional Lie Algebras of U(N+,N-) Tensor Operators and Applications

The structure constants for Moyal brackets of an infinite basis of functions on the algebraic manifolds M of pseudo-unitary groups U(N_+,N_-) are provided. They generalize the Virasoro and W_\infty algebras to higher dimensions. The connection with volume-preserving diffeomorphisms on M, higher generalized-spin and tensor operator algebras of U(N_+,N_-) is discussed. These centrally-extended, infinite-dimensional Lie-algebras provide also the arena for non-linear integrable field theories in higher dimensions, residual gauge symmetries of higher-extended objects in the light-cone gauge and C^*-algebras for tractable non-commutative versions of symmetric curved spaces.Comment: 8 pages, LaTeX, no figures; minor comments added; to appear in J. Phys A (Math. Gen.

On a Matrix Model of Level Structure

We generalize the dimensionally reduced Yang-Mills matrix model by adding d=1 Chern-Simons term and terms for a bosonic vector. The coefficient, \kappa of the Chern-Simons term must be integer, and hence the level structure. We show at the bottom of the Yang-Mills potential, the low energy limit, only the linear motion is allowed for D0 particles. Namely all the particles align themselves on a single straight line subject to \kappa^2/r^2 repulsive potential from each other. We argue the relevant brane configuration to be D0-branes in a D4 after \kappa of D8's pass the system.Comment: 1+6 pages, No figure, LaTeX; Minor changes; To appear in Class. Quant. Gra

Aluminum-, Calcium- And Titanium-Rich Oxide Stardust In Ordinary Chondrite Meteorites

We report isotopic data for a total of 96 presolar oxide grains found in residues of several unequilibrated ordinary chondrite meteorites. Identified grain types include Al2O3, MgAl2O4, hibonite (CaAl12O19) and Ti oxide. This work greatly increases the presolar hibonite database, and is the first report of presolar Ti oxide. O-isotopic compositions of the grains span previously observed ranges and indicate an origin in red giant and asymptotic giant branch (AGB) stars of low mass (<2.5 MSun) for most grains. Cool bottom processing in the parent AGB stars is required to explain isotopic compositions of many grains. Potassium-41 enrichments in hibonite grains are attributable to in situ decay of now-extinct 41Ca. Inferred initial 41Ca/40Ca ratios are in good agreement with model predictions for low-mass AGB star envelopes, provided that ionization suppresses 41Ca decay. Stable Mg and Ca isotopic ratios of most of the hibonite grains reflect primarily the initial compositions of the parent stars and are generally consistent with expectations for Galactic chemical evolution, but require some local interstellar chemical inhomogeneity. Very high 17O/16O or 25Mg/24Mg ratios suggest an origin for some grains in binary star systems where mass transfer from an evolved companion has altered the parent star compositions. A supernova origin for the hitherto enigmatic 18O-rich Group 4 grains is strongly supported by multi-element isotopic data for two grains. The Group 4 data are consistent with an origin in a single supernova in which variable amounts of material from the deep 16O-rich interior mixed with a unique end-member mixture of the outer layers. The Ti oxide grains primarily formed in low-mass AGB stars. They are smaller and rarer than presolar Al2O3, reflecting the lower abundance of Ti than Al in AGB envelopes.Comment: Accepted for publication in ApJ; 47 pages, 13 figure