Lattice Heavy Quark Effective Theory and the Isgur-Wise function

We compute the Isgur-Wise function using heavy quark effective theory formulated on the lattice. The non-relativistic kinetic energy term of the heavy quark is included to the action as well as terms remaining in the infinite quark mass limit. The classical velocity of the heavy quark is renormalized on the lattice and we determine the renormalized velocity non-perturbatively using the energy-momentum dispersion relation. The slope parameter of the Isgur-Wise function at zero recoil is obtained at $\beta=6.0$ on a $24^3\times 48$ lattice for three values of $m_{Q}$.Comment: 14 pages of A4 format and 8 figures in one uuencoded postscript fil

Real-space renormalization group approach for the corner Hamiltonian

We present a real-space renormalization group approach for the corner Hamiltonian, which is relevant to the reduced density matrix in the density matrix renormalization group. A set of self-consistent equations that the renormalized Hamiltonian should satisfy in the thermodynamic limit is also derived from the fixed point of the recursion relation for the corner Hamiltonian. We demonstrate the renormalization group algorithm for the $S=1/2$ XXZ spin chain and show that the results are consistent with the exact solution. We further examine the renormalization group for the S=1 Heisenberg spin chain and then discuss the nature of the eigenvalue spectrum of the corner Hamiltonian for the non-integrable model.Comment: 7 page

BB Decay Constants from NRQCD with Dynamical Fermions

We present a lattice investigation of the heavy-light meson decay constants using Wilson light quarks and NRQCD heavy quarks, partially including the effects of dynamical sea quarks. We calculate the pseudoscalar and vector decay constants over a wide range in heavy quark mass and are able to perform a detailed analysis of heavy quark symmetry. We find consistency between the extrapolation of the NRQCD results and the static case, as expected. We find the slope of the decay constants with $1/M$ is significantly larger than naive expectations and the results of previous lattice calculations. For the first time we extract the non-perturbative coefficients of the slope arising from the $O(1/M)$ heavy quark interactions separately and show the kinetic energy of the heavy quark is dominant and responsible for the large slope. In addition, we find that significant systematic errors remain in the decay constant extracted around the $B$ meson mass due to truncating the NRQCD series at $O(1/M)$. We estimate the higher order contributions to $f_B$ are approximately $20\%$; roughly the same size as the systematic errors introduced by using the Wilson action for light quarks.Comment: 30 pages, Latex, 14 postscript figure

Ab Initio Calculation of Relativistic Corrections to the Static Interquark potential I: SU(2) Gauge Theory

We test the capability of state-of-the-art lattice techniques for a precise determination of relativistic corrections to the static interquark potential, by use of SU(2) gauge theory. Emphasis is put on the short range structure of the spin dependent potentials, with lattice resolution a ranging from a approx 0.04 fm (at beta=2.74) down to a approx 0.02 fm (at beta=2.96) on volumes of 32^4 and 48^4 lattice sites. We find a new short range Coulomb-like contribution to the spin-orbit potential V_1'.Comment: 37 pages REVTeX with 20 encapsuled ps figure

Mesonic correlation lengths in high-temperature QCD

We consider spatial correlation lengths \xi for various QCD light quark bilinears at temperatures above a few hundred MeV. Some of the correlation lengths (such as that related to baryon density) coincide with what has been measured earlier on from glueball-like states; others do not couple to glueballs, and have a well-known perturbative leading-order expression as well as a computable next-to-leading-order correction. We determine the latter following analogies with the NRQCD effective theory, used for the study of heavy quarkonia at zero temperature: we find (for the quenched case) \xi^{-1} = 2 \pi T + 0.1408 g^2 T, and compare with lattice results. One manifestation of U_A(1) symmetry non-restoration is also pointed out.Comment: 25 pages. v2: small clarifications; published versio

Complete O(v^2) corrections to the static interquark potential from SU(3) gauge theory

For the first time, we determine the complete spin- and momentum-dependent order v^2 corrections to the static interquark potential from simulations of QCD in the valence quark approximation at inverse lattice spacings of 2-3 GeV. A new flavor dependent correction to the central potential is found. We report a 1/r^2 contribution to the long range spin-orbit potential V_1'. The other spin-dependent potentials turn out to be short ranged and can be well understood by means of perturbation theory. The momentum-dependent potentials qualitatively agree with minimal area law expectations. In view of spectrum calculations, we discuss the matching of the effective nonrelativistic theory to QCD as well as renormalization of lattice results. In a first survey of the resulting bottomonia and charmonia spectra we reproduce the experimental levels within average errors of 12.5 MeV and 22 MeV, respectively.Comment: 54 pages REVTeX with 24 encapsuled ps figure

The Heavy Hadron Spectrum

I discuss the spectrum of hadrons containing heavy quarks ($b$ or $c$), and how well the experimental results are matched by theoretical ideas. Useful insights come from potential models and applications of Heavy Quark Symmetry and these can be compared with new numerical results from the ab initio methods of Lattice QCD.Comment: 64 pages, Latex, lectures at Schladming Winter School 199

Cellular Radiosensitivity: How much better do we understand it?

Purpose: Ionizing radiation exposure gives rise to a variety of lesions in DNA that result in genetic instability and potentially tumorigenesis or cell death. Radiation extends its effects on DNA by direct interaction or by radiolysis of H2O that generates free radicals or aqueous electrons capable of interacting with and causing indirect damage to DNA. While the various lesions arising in DNA after radiation exposure can contribute to the mutagenising effects of this agent, the potentially most damaging lesion is the DNA double strand break (DSB) that contributes to genome instability and/or cell death. Thus in many cases failure to recognise and/or repair this lesion determines the radiosensitivity status of the cell. DNA repair mechanisms including homologous recombination (HR) and non-homologous end-joining (NHEJ) have evolved to protect cells against DNA DSB. Mutations in proteins that constitute these repair pathways are characterised by radiosensitivity and genome instability. Defects in a number of these proteins also give rise to genetic disorders that feature not only genetic instability but also immunodeficiency, cancer predisposition, neurodegeneration and other pathologies. Conclusions: In the past fifty years our understanding of the cellular response to radiation damage has advanced enormously with insight being gained from a wide range of approaches extending from more basic early studies to the sophisticated approaches used today. In this review we discuss our current understanding of the impact of radiation on the cell and the organism gained from the array of past and present studies and attempt to provide an explanation for what it is that determines the response to radiation

Electroosmotic flow reversal outside glass nanopores.

We report observations of a striking reversal in the direction of electroosmotic flow (EOF) outside a conical glass nanopore as a function of salt concentration. At high ionic strengths (>100 mM), we observe EOF in the expected direction as predicted by classical electrokinetic theory, while at low salt concentrations (<1 mM) the direction of the flow is reversed. The critical crossover salt concentration depends on the pore diameter. Finite-element simulations indicate a competition between the EOF generated from the inner and outer walls of the pore, which drives flows in opposite directions. We have developed a simple analytical model which reveals that, as the salt concentration is reduced, the flow rates inside the pore are geometrically constrained, whereas there is no such limit for flows outside the pore. This model captures all of the essential physics of the system and explains the observed data, highlighting the key role the external environment plays in determining the overall electroosmotic behavior