Low temperature behavior of the heavy Fermion Ce3Co4Sn13

The compound Ce3Co4Sn13 is an extremely heavy cubic heavy fermion system with a low temperature electronic specific heat of order ~4 J/mol-K2. If the compound is nonmagnetic, it would be one of the heaviest nonmagnetic Ce-based heavy fermions reported to date and therefore would be expected to lie extremely close to a quantum critical point. However, a broad peak of unknown origin is observed at 0.8 K in the specific heat and magnetic susceptibility, suggesting the possibility of antiferromagnetic order. We present neutron diffraction data from polycrystalline samples which do not show any sign of magnetic scattering below 0.8 K. In addition, we present inelastic neutron scattering data from a single crystal sample which is consistent with the 1.2 K energy scale for Kondo spin fluctuations determined from specific heat measurements.Comment: 4 pages, 2 figures, submitted to J. Mag. Mag. Mater. for ICM 200

Conformal anomaly and the vector coupling in dense matter

We construct an effective chiral Lagrangian for hadrons implemented by the conformal invariance and discuss the properties of nuclear matter at high density. The model is formulated based on two alternative assignment, "naive" and mirror, of chirality to the nucleons. It is shown that taking the dilaton limit, in which the mended symmetry of Weinberg is manifest, the vector-meson Yukawa coupling becomes suppressed and the symmetry energy becomes softer as one approaches the chiral phase transition. This leads to softer equations of state (EoS) and could accommodate the EoS without any exotica consistent with the recent measurement of a $1.97 \pm 0.04\,M_\odot$ neutron star.Comment: v2:10 pages, 2 figures, typos corrected, a rough estimate of m0 adde

The Solar pp and hep Processes in Effective Field Theory

The strategy of modern effective field theory is exploited to pin down accurately the flux $S$ factors for the $pp$ and $hep$ processes in the Sun. The technique used is to combine the high accuracy established in few-nucleon systems of the "standard nuclear physics approach" (SNPA) and the systematic power counting of chiral perturbation theory (ChPT) into a consistent effective field theory framework. Using highly accurate wave functions obtained in the SNPA and working to \nlo3 in the chiral counting for the current, we make totally parameter-free and error-controlled predictions for the $pp$ and $hep$ processes in the Sun.Comment: 5 pages, aipproc macros are included. Talk given at International Nuclear Physics Conference 2001, Berkeley, California, July 30 - August 3, 200

Effective field theory of the deuteron with dibaryon field

Pionless effective field theory with dibaryon fields is reexamined for observables involving the deuteron. The electromagnetic form factors of the deuteron and the total cross sections of radiative neutron capture on the proton, $np \to d\gamma$, are calculated. The low energy constants of vector(photon)-dibaryon-dibaryon vertices in the effective lagrangian are fixed primarily by the one-body vector(photon)-nucleon-nucleon interactions. This scheme for fixing the values of the low energy constants satisfactorily reproduces the results of the effective range theory. We also show that, by including higher order corrections, one can obtain results that are close to those of Argonne v18 potential model.Comment: 25 pages and 11 figures; 16 references added, Figure 6 and 7 replotted, text revised a lot. To be published in Phys. Rev.

Designing nanophotonic structures using conditional deep convolutional generative adversarial networks

Data-driven design approaches based on deep learning have been introduced in nanophotonics to reduce time-consuming iterative simulations, which have been a major challenge. Here, we report the first use of conditional deep convolutional generative adversarial networks to design nanophotonic antennae that are not constrained to predefined shapes. For given input reflection spectra, the network generates desirable designs in the form of images; this allows suggestions of new structures that cannot be represented by structural parameters. Simulation results obtained from the generated designs agree well with the input reflection spectrum. This method opens new avenues toward the development of nanophotonics by providing a fast and convenient approach to the design of complex nanophotonic structures that have desired optical properties.11Ysciescopu

Half-Skyrmions and the Equation of State for Compact-Star Matter

The half-skyrmions that appear in dense baryonic matter when skyrmions are put on crystals modify drastically hadron properties in dense medium and affect strongly the nuclear tensor forces, thereby influencing the equation of state (EoS) of dense nuclear and asymmetric nuclear matter. The matter comprised of half skyrmions has vanishing quark condensate but non-vanishing pion decay constant and could be interpreted as a hadronic dual of strong-coupled quark matter. We infer from this observation combined with certain predictions of hidden local symmetry in low-energy hadronic interactionsa a set of new scaling laws -- called "new-BR" -- for the parameters in nuclear effective field theory controlled by renormalization-group flow. They are subjected to the EoS of symmetric and asymmetric nuclear matter, and are then applied to nuclear symmetry energies and properties of compact stars. The changeover from the skyrmion matter to a half-skyrmion matter that takes place after the cross-over density $n_{1/2}$ provides a simple and natural field theoretic explanation for the change of the EoS from soft to stiff at a density above that of nuclear matter required for compact stars as massive as $\sim 2.4M_\odot$. Cross-over density in the range 1.5n_0 \lsim n_{1/2} \lsim 2.0 n_0 has been employed, and the possible skyrmion half-skyrmion coexistence {or cross-over} near $n_{1/2}$ is discussed. The novel structure of {the tensor forces and} the EoS obtained with the new-BR scaling is relevant for neutron-rich nuclei and compact star matter and could be studied in RIB (rare isotope beam) machines.Comment: 12 pages, 7 figures, slightly revised for PRC, in pres

Radiative neutron capture on a proton at BBN energies

The total cross section for radiative neutron capture on a proton, $np \to d \gamma$, is evaluated at big bang nucleosynthesis (BBN) energies. The electromagnetic transition amplitudes are calculated up to next-to leading order within the framework of pionless effective field theory with dibaryon fields. We also calculate the $d\gamma\to np$ cross section and the photon analyzing power for the $d\vec{\gamma}\to np$ process from the amplitudes. The values of low energy constants that appear in the amplitudes are estimated by a Markov Chain Monte Carlo analysis using the relevant low energy experimental data. Our result agrees well with those of other theoretical calculations except for the $np\to d\gamma$ cross section at some energies estimated by an R-matrix analysis. We also study the uncertainties in our estimation of the $np\to d\gamma$ cross section at relevant BBN energies and find that the estimated cross section is reliable to within $\sim$1% error.Comment: 21 pages and 12 eps figures; 6 eps figures and 2 references added, and accepted for publication in Phys. Rev.

Message from the ISPA 2011 program chairs

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