The Worldsheet Formulation as an Alternative Method for Simulating Dynamical Fermions

The recently proposed worldsheet formulation of lattice fermions is tested for the first time carrying out a simulation for the simplest model: the one-flavor, strictly massless lattice Schwinger model. A main advantage of this alternative method for simulating dynamical fermions consists in its economy: it involves many fewer degrees of freedom than the ordinary Kogut-Susskind formulation. The known continuum limit is reproduced by the method for relatively small lattices.Comment: 4 pages, 1 eps figure, revte

Finite Lattice Hamiltonian Computations in the P-Representation: the Schwinger Model

The Schwinger model is studied in a finite lattice by means of the P-representation. The vacuum energy, mass gap and chiral condensate are evaluated showing good agreement with the expected values in the continuum limit.Comment: 6 pages, 5 eps figures, espcrc

Book Review: Was Hinduism Invented? : Britons, Indians, and Colonial Construction of Religion

A review of Was Hinduism Invented? : Britons, Indians, and Colonial Construction of Religion by Brian K. Pennington

A radial mass profile analysis of the lensing cluster MS2137-23

We reanalyze the strong lens modeling of the cluster of galaxies MS2137-23 using a new data set obtained with the ESO VLT. We found the photometric redshifts of the two main arc systems are both at z=1.6. After subtraction of the central cD star light of the HST image we found that only one object lying underneath has the expected properties of the fifth image associated to the tangential arc. We improve the previous lens modelings of the central dark matter distribution of the cluster, using an isothermal model with a core (IS) and the NFW-like model with a cusp. Without the fifth image, the arc properties together with the shear map profile are equally well fit by the and by an IS and a sub-class of generalized-NFW mass profiles having inner slope power index in the range 0.7<alpha<1.2. Adding new constrains provided by the fifth image favors IS profiles that better predict the fifth image properties. A model including cluster galaxy perturbations or the the stellar mass distribution does not change our conclusions but imposes the M/L_I of the cD stellar component is below 10 at a 99% confidence level. Using our new detailed lensing model together with Chandra X-ray data and the cD stellar component we finally discuss intrinsic properties of the gravitational potential. Whereas X-ray and dark matter have a similar shape at various radius, the cD stellar isophotes are twisted by 13 deg. The sub- arc-second azimuthal shift we observe between the radial arc position and the predictions of elliptical models correspond to what is expected from a mass distribution twist. This shift may result from a projection effect of the cD and the cluster halos, thus revealing the triaxiality of the system.Comment: Final version accepted in A&