Heavy flavor diffusion in weakly coupled N=4 Super Yang-Mills theory

We use perturbation theory to compute the diffusion coefficient of a heavy quark or scalar moving in N=4 SU(N_c) Super Yang-Mills plasma to leading order in the coupling and the ratio T/M<<1. The result is compared both to recent strong coupling calculations in the same theory and to the corresponding weak coupling result in QCD. Finally, we present a compact and simple formulation of the Lagrangian of our theory, N=4 SYM coupled to a massive fundamental N=2 hypermultiplet, which is well-suited for weak coupling expansions.Comment: 22 pages, 4 figures; v3: error corrected in calculations, figures and discussion modified accordingl

Charge-Symmetry Breaking and the Two-Pion-Exchange Two-Nucleon Interaction

Charge-symmetry breaking in the nucleon-nucleon force is investigated within an effective field theory, using a classification of isospin-violating interactions based on power-counting arguments. The relevant charge-symmetry-breaking interactions corresponding to the first two orders in the power counting are discussed, including their effects on the 3He-3H binding-energy difference. The static charge-symmetry-breaking potential linear in the nucleon-mass difference is constructed using chiral perturbation theory. Explicit formulae in momentum and configuration spaces are presented. The present work completes previously obtained results.Comment: 15 pages, 2 figure

Fermion zero modes in N=2 supervortices

We study the fermionic zero modes of BPS semilocal magnetic vortices in N=2 supersymmetric QED with a Fayet-Iliopoulos term and two matter hypermultiplets of opposite charge. There is a one-parameter family of vortices with arbitrarily wide magnetic cores. Contrary to the situation in pure Nielsen-Olesen vortices, new zero modes are found which get their masses from Yukawa couplings to scalar fields that do not wind and are non-zero at the core. We clarify the relation between fermion mass and zero modes. The new zero modes have opposite chiralities and therefore do not affect the net counting (left minus right) of zero modes coming from index theorems but manage to evade other index theorems in the literature that count the total number (left plus right) of zero modes in simpler systems.Comment: 9 pages, 1 figure. Uses Revtex4. Revised version includes discussion about the back-reaction of the fermions on the background vortex. Version to be published in Phys. Rev.

A Quantum Hall Fluid of Vortices

In this note we demonstrate that vortices in a non-relativistic Chern-Simons theory form a quantum Hall fluid. We show that the vortex dynamics is controlled by the matrix mechanics previously proposed by Polychronakos as a description of the quantum Hall droplet. As the number of vortices becomes large, they fill the plane and a hydrodynamic treatment becomes possible, resulting in the non-commutative theory of Susskind. Key to the story is the recent D-brane realisation of vortices and their moduli spaces.Comment: 10 pages. v2(3): (More) References adde

Interactions for a collection of spin-two fields intermediated by a massless p-form

Under the general hypotheses of locality, smoothness of interactions in the coupling constant, Poincare invariance, Lorentz covariance, and preservation of the number of derivatives on each field, we investigate the cross-couplings of one or several spin-two fields to a massless p-form. Two complementary cases arise. The first case is related to the standard interactions from General Relativity, but the second case describes a new, special type of couplings in D=p+2 spacetime dimensions, which break the PT-invariance. Nevertheless, no consistent, indirect cross-interactions among different gravitons with a positively defined metric in internal space can be constructed.Comment: LaTeX; the content of v2 has been changed, some former results have been changed, new material has been added; accepted for publication in Nuclear Physics

Soft two-meson-exchange nucleon-nucleon potentials. I. Planar and crossed-box diagrams

Pion-meson-exchange nucleon-nucleon potentials are derived for two nucleons in the intermediate states. The mesons we include are (i) pseudoscalar mesons: $\pi, \eta, \eta'$; (ii) vector mesons: $\rho, \omega, \phi$; (iii) scalar mesons: $a_{0}(980), \varepsilon(760), f_{0}(975)$; and (iv) the $J=0$ contribution from the Pomeron. Strong dynamical pair suppression is assumed, and at the nucleon-nucleon-meson vertices Gaussian form factors are incorporated into the relativistic two-body framework using a dispersion representation for the pion- and meson-exchange amplitudes. The Fourier transformations are performed using factorization techniques for the energy denominators. The potentials are first calculated in the adiabatic approximation to all planar and crossed three-dimensional momentum-space $\pi$-meson diagrams. Next, we calculate the $1/M$ corrections.Comment: 28 pages RevTeX, 8 postscript figures; revised version as to appear in Phys. Rev.

Lattice calculations for A=3,4,6,12 nuclei using chiral effective field theory

We present lattice calculations for the ground state energies of tritium, helium-3, helium-4, lithium-6, and carbon-12 nuclei. Our results were previously summarized in a letter publication. This paper provides full details of the calculations. We include isospin-breaking, Coulomb effects, and interactions up to next-to-next-to-leading order in chiral effective field theory.Comment: 38 pages, 11 figures, final publication versio

Brane World Cosmologies and Statistical Properties of Gravitational Lenses

Brane world cosmologies seem to provide an alternative explanation for the present accelerated stage of the Universe with no need to invoke either a cosmological constant or an exotic \emph{quintessence} component. In this paper we investigate statistical properties of gravitational lenses for some particular scenarios based on this large scale modification of gravity. We show that a large class of such models are compatible with the current lensing data for values of the matter density parameter $\Omega_{\rm{m}} \leq 0.94$ ($1\sigma$). If one fixes $\Omega_{\rm{m}}$ to be $\simeq 0.3$, as suggested by most of the dynamical estimates of the quantity of matter in the Universe, the predicted number of lensed quasars requires a slightly open universe with a crossover distance between the 4 and 5-dimensional gravities of the order of $1.76 H_o^{-1}$.Comment: 6 pages, 3 figures, revte

Three-Nucleon Force Effects in Nucleon Induced Deuteron Breakup: Predictions of Current Models (I)

An extensive study of three-nucleon force effects in the entire phase space of the nucleon-deuteron breakup process, for energies from above the deuteron breakup threshold up to 200 MeV, has been performed. 3N Faddeev equations have been solved rigorously using the modern high precision nucleon-nucleon potentials AV18, CD Bonn, Nijm I, II and Nijm 93, and also adding 3N forces. We compare predictions for cross sections and various polarization observables when NN forces are used alone or when the two pion-exchange Tucson-Melbourne 3NF was combined with each of them. In addition AV18 was combined with the Urbana IX 3NF and CD Bonn with the TM' 3NF, which is a modified version of the TM 3NF, more consistent with chiral symmetry. Large but generally model dependent 3NF effects have been found in certain breakup configurations, especially at the higher energies, both for cross sections and spin observables. These results demonstrate the usefulness of the kinematically complete breakup reaction in testing the proper structure of 3N forces.Comment: 42 pages, 20 ps figures, 2 gif figure

Universal Correlations in Pion-less EFT with the Resonating Group Model: Three and Four Nucleons

The Effective Field Theory "without pions" at next-to-leading order is used to analyze universal bound state and scattering properties of the 3- and 4-nucleon system. Results of a variety of phase shift equivalent nuclear potentials are presented for bound state properties of 3H and 4He, and for the singlet S-wave 3He-neutron scattering length a_0(3He-n). The calculations are performed with the Refined Resonating Group Method and include a full treatment of the Coulomb interaction and the leading-order 3-nucleon interaction. The results compare favorably with data and values from AV18(+UIX) model calculations. A new correlation between a_0(3He-n) and the 3H binding energy is found. Furthermore, we confirm at next-to-leading order the correlations, already found at leading-order, between the 3H binding energy and the 3H charge radius, and the Tjon line. With the 3H binding energy as input, we get predictions of the Effective Field Theory "without pions" at next-to-leading order for the root mean square charge radius of 3H of (1.6\pm 0.2) fm, for the 4He binding energy of (28\pm 2.5) MeV, and for Re(a_0(3He-n)) of (7.5\pm 0.6)fm. Including the Coulomb interaction, the splitting in binding energy between 3H and 3He is found to be (0.66\pm 0.03) MeV. The discrepancy to data of (0.10\mp 0.03) MeV is model independently attributed to higher order charge independence breaking interactions. We also demonstrate that different results for the same observable stem from higher order effects, and carefully assess that numerical uncertainties are negligible. Our results demonstrate the convergence and usefulness of the pion-less theory at next-to-leading order in the 4He channel. We conclude that no 4-nucleon interaction is needed to renormalize the theory at next-to-leading order in the 4-nucleon sector.Comment: 24 pages revtex4, including 8 figures as .eps files embedded with includegraphicx, leading-order results added, calculations include the LO three-nucleon interaction explicitly, comment on Wigner bound added, minor modification