Classical Supersymmetric Mechanics

We analyse a supersymmetric mechanical model derived from (1+1)-dimensional field theory with Yukawa interaction, assuming that all physical variables take their values in a Grassmann algebra B. Utilizing the symmetries of the model we demonstrate how for a certain class of potentials the equations of motion can be solved completely for any B. In a second approach we suppose that the Grassmann algebra is finitely generated, decompose the dynamical variables into real components and devise a layer-by-layer strategy to solve the equations of motion for arbitrary potential. We examine the possible types of motion for both bosonic and fermionic quantities and show how symmetries relate the former to the latter in a geometrical way. In particular, we investigate oscillatory motion, applying results of Floquet theory, in order to elucidate the role that energy variations of the lower order quantities play in determining the quantities of higher order in B.Comment: 29 pages, 2 figures, submitted to Annals of Physic

Compactifications of Heterotic Theory on Non-Kahler Complex Manifolds: I

We study new compactifications of the SO(32) heterotic string theory on compact complex non-Kahler manifolds. These manifolds have many interesting features like fewer moduli, torsional constraints, vanishing Euler character and vanishing first Chern class, which make the four-dimensional theory phenomenologically attractive. We take a particular compact example studied earlier and determine various geometrical properties of it. In particular we calculate the warp factor and study the sigma model description of strings propagating on these backgrounds. The anomaly cancellation condition and enhanced gauge symmetry are shown to arise naturally in this framework, if one considers the effect of singularities carefully. We then give a detailed mathematical analysis of these manifolds and construct a large class of them. The existence of a holomorphic (3,0) form is important for the construction. We clarify some of the topological properties of these manifolds and evaluate the Betti numbers. We also determine the superpotential and argue that the radial modulus of these manifolds can actually be stabilized.Comment: 75 pages, Harvmac, no figures; v2: Some new results added, typos corrected and references updated. Final version to appear in JHE

Error bounds for the large-argument asymptotic expansions of the Hankel and Bessel functions

In this paper, we reconsider the large-argument asymptotic expansions of the Hankel, Bessel and modified Bessel functions and their derivatives. New integral representations for the remainder terms of these asymptotic expansions are found and used to obtain sharp and realistic error bounds. We also give re-expansions for these remainder terms and provide their error estimates. A detailed discussion on the sharpness of our error bounds and their relation to other results in the literature is given. The techniques used in this paper should also generalize to asymptotic expansions which arise from an application of the method of steepest descents.Comment: 32 pages, 2 figures, accepted for publication in Acta Applicandae Mathematica

Time Evolution in Open String Theory

We discuss a general iterative procedure for constructing time dependent solutions in open string theory describing rolling of a generic tachyon field away from its maximum. These solutions are characterized by two parameters labelling the initial position and velocity of the tachyon field, but one of these parameters can be removed by using time translation symmetry. The Wick rotated version of the resulting one parameter family of inequivalent solutions describes a one parameter family of boundary conformal field theories, each member of which is related to the boundary conformal field theory describing the original D-brane system by a nearly marginal deformation. We apply this technique to construct a time dependent solution on a D-brane in bosonic string theory which can be interpreted as the creation of a lower dimensional brane during the decay of an unstable D-brane.Comment: LaTeX file, 35 pages, 2 figures, discussion on multiple rolling tachyons expanded to include the general case, references added; v4: typos correcte

Constraining the electric charges of some astronomical bodies in Reissner-Nordstrom spacetimes and generic r^-2-type power-law potentials from orbital motions

We put model-independent, dynamical constraints on the net electric charge Q of some astronomical and astrophysical objects by assuming that their exterior spacetimes are described by the Reissner-Nordstroem metric, which induces an additional potential U_RN \propto Q^2 r^-2. Our results extend to other hypothetical power-law interactions inducing extra-potentials U_pert = r^-2 as well (abridged).Comment: LaTex2e, 16 pages, 3 figures, no tables, 128 references. Version matching the one at press in General Relativity and Gravitation (GRG). arXiv admin note: substantial text overlap with arXiv:1112.351

Search for long-lived doubly charged Higgs bosons in p(p)over-bar collisions at root s=1.96 TeV

We present a search for long-lived doubly charged Higgs bosons (H+/-+/-), with signatures of high ionization energy loss and muonlike penetration. We use 292 pb(-1) of data collected in p (p) over bar collisions at root s=1.96 TeV by the CDF II detector at the Fermilab Tevatron. Observing no evidence of long-lived doubly charged particle production, we exclude H-L(+/-+/-) and H-R(+/-+/-) bosons with masses below 133 GeV/c(2) and 109 GeV/c(2), respectively. In the degenerate case we exclude H+/-+/- mass below 146 GeV/c(2). All limits are quoted at the 95% confidence level

Measurement of the W+W- Production Cross Section in ppbar Collisions at sqrt(s)=1.96 TeV using Dilepton Events

We present a measurement of the W+W- production cross section using 184/pb of ppbar collisions at a center-of-mass energy of 1.96 TeV collected with the Collider Detector at Fermilab. Using the dilepton decay channel W+W- -> l+l-vvbar, where the charged leptons can be either electrons or muons, we find 17 candidate events compared to an expected background of 5.0+2.2-0.8 events. The resulting W+W- production cross section measurement of sigma(ppbar -> W+W-) = 14.6 +5.8 -5.1 (stat) +1.8 -3.0 (syst) +-0.9 (lum) pb agrees well with the Standard Model expectation.Comment: 8 pages, 2 figures, 2 tables. To be submitted to Physical Review Letter

Measurement of the ttbar Production Cross Section in ppbar collisions at sqrt s = 1.96 TeV in the All Hadronic Decay Mode

We report a measurement of the ttbar production cross section using the CDF-II detector at the Fermilab Tevatron. The analysis is performed using 311 pb-1 of ppbar collisions at sqrt(s)=1.96 TeV. The data consist of events selected with six or more hadronic jets with additional kinematic requirements. At least one of these jets must be identified as a b-quark jet by the reconstruction of a secondary vertex. The cross section is measured to be sigma(tbart)=7.5+-2.1(stat.)+3.3-2.2(syst.)+0.5-0.4(lumi.) pb, which is consistent with the standard model prediction.Comment: By CDF collaboratio