Charmonium properties in hot quenched lattice QCD

We study the properties of charmonium states at finite temperature in quenched QCD on large and fine isotropic lattices. We perform a detailed analysis of charmonium correlation and spectral functions both below and above $T_c$. Our analysis suggests that both S wave states ($J/\psi$ and $\eta_c$) and P wave states ($\chi_{c0}$ and $\chi_{c1}$) disappear already at about $1.5 T_c$. The charm diffusion coefficient is estimated through the Kubo formula and found to be compatible with zero below $T_c$ and approximately $1/\pi T$ at $1.5 T_c\lesssim T\lesssim 3 T_c$.Comment: 32 pages, 19 figures, typo corrected, discussions on isotropic vs anisotropic lattices expanded, published versio

Heavy Quark diffusion from lattice QCD spectral functions

We analyze the low frequency part of charmonium spectral functions on large lattices close to the continuum limit in the temperature region $1.5\lesssim T/T_c\lesssim 3$ as well as for $T \simeq 0.75T_c$. We present evidence for the existence of a transport peak above $T_c$ and its absence below $T_c$. The heavy quark diffusion constant is then estimated using the Kubo formula. As part of the calculation we also determine the temperature dependence of the signature for the charmonium bound state in the spectral function and discuss the fate of charmonium states in the hot medium.Comment: 4 pages, Proceedings for Quark Matter 2011 Conference, May 23-28, 2011, Annecy, Franc

Direct observation of particle-hole mixing in the superconducting state by angle-resolved photoemission

Particle-hole (p-h) mixing is a fundamental consequence of the existence of a pair condensate. We present direct experimental evidence for p-h mixing in the angle-resolved photoemission (ARPES) spectra in the superconducting state of Bi_2Sr_2CaCu_2O_{8+\delta}. In addition to its pedagogical importance, this establishes unambiguously that the gap observed in ARPES is associated with superconductivity.Comment: 3 pages, revtex, 4 postscript figure

Single crystal growth and physical properties of SrFe2_{2}(As1−x_{1-x}Px_{x})2_{2}

We report a crystal growth and physical properties of SrFe$_{2}$(As$_{1-x}$P$_{x}$)$_{2}$. The single crystals for various $x$s were grown by a self flux method. For $x = 0.35$, $T_c$ reaches the maximum value of 30\,K and the electrical resistivity $\rho$($T$) shows $T$-linear dependence. As $x$ increases, $T_{c}$ decreases and $\rho$($T$) changes to $T^2$-behavior, indicating a standard Fermi liquid. These results suggest that a magnetic quantum critical point exists around $x=0.35$.Comment: 4 pages, 4 figures, accepted to Supplemental issue of the Journal of Physical Society of Japan (JPSJ