The most general set of new physics effective operators contributing to the decay of an unpolarized top quark into a bottom quark and a W gauge boson are considered at next-to-leading order in QCD. We find that the dipole operator contribution to the transverse-plus W helicity fraction F+ is enhanced compared to the leading order result at non-vanishing bottom quark mass. Nonetheless, presently...

Nuclear muon capture on the proton and He is considered both within and beyond the Standard Model in terms as general as is possible. Explicit and precise analytic expressions for all possible observables are given, assuming only a Dirac neutrino in the limit of vanishing mass. These results allow both for precision tests of the Standard Model and new physics, as well as for the assessment of t...

We present several variational approaches for fluid flow estimation from image sequences in experimental fluid dynamics. These approaches enable the contextual data analysis of particle images based on physical constraints, including bounds on the variation of divergence and vorticity of flow patterns, vanishing divergence for incompressible flows, and iterative estimation-prediction schemes ba...

An extension of the Legendre transform to non-convex functions with vanishing Hessian as a mix of envelope and general solutions of the Clairaut equation is proposed. Applying this to constraint systems, the procedure of finding a Hamiltonian for a singular Lagrangian is just that of solving a corresponding Clairaut equation with a subsequent application of the proposed Legendre-Clairaut transf...

A fast and simple Monte Carlo program is presented that simulates single Bremsstrahlung in Bhabha scattering, ee → eeγ, without constraints on scattering angles. This allows the study of this process at arbitrarily small, or even vanishing, scattering angles. Experimental cuts can be imposed on an event-by-event basis, allowing for detailed studies of the process as a limitation to beam lifetim...

We examine the problem of supersymmetry breaking in realistic superstring standard–like models which are constructed in the free fermionic formulation. We impose a supersymmetric vacuum at the Planck scale by requiring vanishing F and D constraints at the cubic level of the superpotential. We then study possible scenarios for supersymmetry breaking by examining the role of nonrenormalizable ter...

Random instances of constraint satisfaction problems such as k-SAT provide challenging benchmarks. If there are m constraints over n variables there is typically a large range of densities r = m/n where solutions are known to exist with probability close to one due to non-constructive arguments. However, no algorithms are known to find solutions efficiently with a non-vanishing probability at e...

We analyze ill-defined pinch singularities characteristic of out of equilibrium thermal field theories. We identify two mechanisms that eliminate pinching even at the single selfenergy insertion approximation to the propagator: the first is based on the vanishing of phase space at the singular point (threshold effect). It is effective in QED with a massive electron and a massless photon. In mas...

We consider (2+1)-gravity with vanishing cosmological constant as a constrained dynamical system. By applying Dirac’s gauge fixing procedure, we implement the constraints and determine the Dirac bracket on the gauge-invariant phase space. The chosen gauge fixing conditions have a natural physical interpretation and specify an observer in the spacetime. We derive explicit expressions for the res...

A covariant spin-foam formulation of quantum gravity has been recently developed, characterized by a kinematics which appears to match well the one of canonical loop quantum gravity. In this paper we reconsider the implementation of the constraints that defines the model. We define in a simple way the boundary Hilbert space of the theory, introducing a slight modification of the embedding of th...