Modern Physics Letters A

Direct detection of WIMPs is key to understand the origin and composition of Dark Matter. Among the many experimental techniques available, those providing directional information have the potential of yielding an unambiguous observation of WIMPs even in the presence of insidious backgrounds. A measurement of the distribution of arrival direction of WIMPs can also discriminate between Galactic Dark Matter halo models. Here, we will discuss the motivation for directional detectors and review the experimental techniques used by the various experiments. We will then describe the DMTPC detector in more detail.

We show how to get a noncommutative product for functions on spacetime starting from the deformation of the coproduct of the Poincaré group using the Drinfel'd twist. Thus it is easy to see that the commutative algebra of functions on spacetime (ℝ⁴) can be identified as the set of functions on the Poincaré group invariant under the right action of the Lorentz group provided we use the standard coproduct for the Poincaré group. We obtain our results for the noncommutative Moyal plane by generalizing this result to the case of the twisted coproduct. This extension is not trivial and involves cohomological features.

As is known, spacetime algebra fixes the coproduct on the diffeomorphism group of the manifold. We now see that the influence is reciprocal: they are strongly tied.

When using dimensional regularization, the bare couplings are expressed as a power series in (2-n/2)^-1 where n is the number of dimensions. It is shown how the renormalization group can be used to sum the leading pole, next-to-leading pole etc. contributions to these sums in scalar electrodynamics (or any theory with multiple couplings).

A chiral black hole can be defined by the three-dimensional pure gravitational Chern–Simons action as an independent gravitational theory. The third-order derivative of the Cotton tensor gives a dimensional constant which plays a role of the cosmological constant. The handedness of angular momentum depends on the signature of the Chern–Simons coefficient. Even in the massless black hole which corresponds to the static black hole, it has a nonvanishing angular momentum. We also discuss three different entropies depending on the methods of Wald, Cardy and 't Hooft.

Here we consider the case of primary scalar unparticle contributions to B_{d, s} mixing. With particular emphasis on the impact of the recent hint of new physics in the measurement of the B_s mixing phase, ϕ_s, we determine the allowed parameter space and impose bounds on the unparticle couplings.

In this paper, a spatially homogeneous and anisotropic Bianchi type V model filled with an imperfect fluid with both viscosity and heat conduction is investigated within the framework of Lyra's geometry. Exact solutions of the field equations are obtained by applying a special law of variation for Hubble's parameter which yields a constant value of the deceleration parameter. Two different physically viable models of the universe are presented in two types of cosmologies, one with power-law expansion and other one with exponential expansion. Cosmological model with power-law expansion has an initial big-bang type singularity at t = 0 whereas the model with exponential expansion has a singularity in the infinite past. The physical and dynamical properties of the models are discussed.

The Euler–Heisenberg effective Lagrangian is used to obtain general expressions for electric and magnetic fields induced by nonlinearity, to leading order in the nonlinear expansion parameter, and for quasistatic situations. These expressions are then used to compute the induced electromagnetic fields due to a spherical shell with uniform charge distribution on the surface, in the presence of an external constant magnetic field. The induced electric field contains several multipole terms with unusual angular dependences. Most importantly, the leading term of the induced magnetic field is due to an induced magnetic dipole moment.

By approximating the centrifugal term in terms of a new approximation scheme, we solve the Schrödinger equation with the arbitrary angular momentum for the Manning–Rosen potential. The bound state energy eigenvalues and the unnormalized radial wave functions have been approximately obtained by using the supersymmetric shape invariance approach and the function analysis method. The numerical experiments show that our approximate analytical results are in better agreement with those obtained by using the numerical integration procedure than the analytical results obtained by using the conventional approximation scheme to deal with the centrifugal term.