[en] For 17 days in August and September 2002, the LIGO and GEO interferometer gravitational wave detectors were operated in coincidence to produce their first data for scientific analysis. Although the detectors were still far from their design sensitivity levels, the data can be used to place better upper limits on the flux of gravitational waves incident on the earth than previous direct measurements. This paper describes the instruments and the data in some detail, as a companion to analysis papers based on the first data

[en] Published in summary form only

[en] If massive invisible particles are pair-produced in a three-body decay, then the energy distribution of the other (visible) product is sensitive to the mass of the invisible pair. We use this fact in the context of a Higgs boson decaying into (i) a Z-boson and two massive neutrinos of a fourth generation, and (ii) a Z and two lightest supersymmetric particles in the minimal supersymmetric standard model. We discuss how the Z-energy spectrum in each case can reflect the values of the parameters of such models. (author). 18 refs, 3 figs

[en] We consider the generation of the baryon asymmetry of the universe through R-parity violation in a scenario in which the out-of-equilibrium condition is satisfied by making the electroweak phase transition first order. We study all the R-parity-violating interactions which can generate (B-L) asymmetry which then converts to the baryon asymmetry of the universe. We demonstrate that CP-violating sfermion decays contribute more than that of the neutralino decays in the generation of (B-L) asymmetry. copyright 1997 The American Physical Society

[en] We consider the decays of a B_s meson into a pair of lightest supersymmetric particles (LSP's) in the minimal supersymmetric standard model. It is found that the parameter space for light LSP's in the range of 1 GeV can be appreciably constrained by looking for such decays

[en] In a supersymmetric model with the lightest supersymmetric particle (LSP) χ in the range of a few hundred MeV close-quote s, the decay τ→μχχ is allowed. We investigate the departure from τ universality caused by this decay which can be triggered by neutrino masses. It is found that universality violation in this way can be greater than both nonuniversal electroweak radiative corrections and supersymmetric one-loop corrections over a considerable region of the parameter space allowed by experiments so far. Thus it suggests a method of constraining the parameter space with light LSP close-quote s using data from τ factories. copyright 1996 The American Physical Society

[en] Colloidal particles with active boundary layers—regions surrounding the particles where non-equilibrium processes produce large velocity gradients—are common in many physical, chemical and biological contexts. The velocity or stress at the edge of the boundary layer determines the exterior fluid flow and, hence, the many-body interparticle hydrodynamic interaction. Here, we present a method to compute the many-body hydrodynamic interaction between N spherical active particles induced by their exterior microhydrodynamic flow. First, we use a boundary integral representation of the Stokes equation to eliminate bulk fluid degrees of freedom. Then, we expand the boundary velocities and tractions of the integral representation in an infinite-dimensional basis of tensorial spherical harmonics and, on enforcing boundary conditions in a weak sense on the surface of each particle, obtain a system of linear algebraic equations for the unknown expansion coefficients. The truncation of the infinite series, fixed by the degree of accuracy required, yields a finite linear system that can be solved accurately and efficiently by iterative methods. The solution linearly relates the unknown rigid body motion to the known values of the expansion coefficients, motivating the introduction of propulsion matrices. These matrices completely characterize hydrodynamic interactions in active suspensions just as mobility matrices completely characterize hydrodynamic interactions in passive suspensions. The reduction in the dimensionality of the problem, from a three-dimensional partial differential equation to a two-dimensional integral equation, allows for dynamic simulations of hundreds of thousands of active particles on multi-core computational architectures. In our simulation of 10"4 active colloidal particle in a harmonic trap, we find that the necessary and sufficient ingredients to obtain steady-state convective currents, the so-called ‘self-assembled pump’, are (a) one-body self-propulsion and (b) two-body rotation from the vorticity of the Stokeslet induced in the trap. (paper)

[en] We have developed a Cantilever Beam Magnetometer (CBM) for ex situ studies on spintronic materials. The indigenously developed experimental set up uses the optical technique to measure the deflection of the specially designed Si cantilever. The material to be studied is either deposited on one face of the Si substrate as thin film or attached to it in bulk form using a special wax. The deflection is achieved using mutually perpendicular magnetic fields and magnetic properties such as magnetization, magnetostriction and magnetocrystalline anisotropy can be studied on this system. This developed experimental technique is the first of its kind in India. (author)

[en] Supersymmetry inspired factorization method is used to obtain exact analytic solutions for one or a few quantum states of general polynomial potentials with or without Coulomb term under suitable constraints on the potential parameters. Illustrative examples and numerical implications of our approach are discussed. (orig.)

[en] If a light gaugino sector exists in the supersymmetric standard model then the mass of lightest neutralino may be of the order of 1 GeV or less. As a consequence of neutral flavor violation in supersymmetric theories B_s-meson may decay into a pair of lightest neutralinos in such a case. It is found that the parameter space for such light neutralinos can be appreciably constrained by looking for such decays. We also show how a rare B-decays (B → K(K^*) + invisible channels) can help us in probing a light neutralino in B-factories in a reasonably model-independent manner. Finally, we observe that the decay of a tau-lepton into a muon and a pair of light neutralinos can cause a violation of weak universality which is larger in magnitude than that from any source known so far. (author). 22 refs, 2 figs