Off-Diagonal Fermion-Higgs Couplings

The flavour changing neutral current (FCNC) decay induced by a Higgs boson in the standard model with three and four generations has been studied. This process occurs first at one-loop order, where it has been calculated neglecting the mass of the outgoing quark. The possibility of producing the as yet undiscovered Higgs boson H by this decay has been considered. In particular we consider the decay of a fourth generation b' quark; the FCNC decay b'→ bH may dominate the charged current (CC) decay modes if the b' mass is less than the top quark mass, for Higgs mass up to 60 Gev. The decay of the top quark, in the presence of a fourth generation, is also discussed

Optimized Topological Quantum Compilation of Three-Qubit Controlled Gates in the Fibonacci Anyon Model: A Controlled-Injection Approach

A method, termed controlled-injection, is proposed for compiling three-qubit controlled gates within the non-abelian Fibonacci anyon model. Building on single-qubit compilation techniques with three Fibonacci anyons, the approach showcases enhanced accuracy and reduced braid length compared to the conventional decomposition method for the controlled three-qubit gates. This method necessitates only four two-qubit gates for decomposition, a notable reduction from the conventional five. In conjunction, the study introduces a novel class of controlled three-qubit gates and conducts a numerical simulation of the topological iToffoli gate to validate the approach. In addition, we propose an optimization method for single-qubit gate approximation using novel algebraic relations and numerical methods, including distributed computing.Comment: 12 pages, 8 figures, 9 table

A New Limit for the Non-Commutative Space-Time Parameter

We study space-time noncommutativity applied to the hydrogen atom and the phenomenological aspects induced. We find that the noncommutative effects are similar to those obtained by considering the extended charged nature of the proton in the atom. To the first order in the noncommutative parameter, it is equivalent to an electron in the fields of a Coulomb potential and an electric dipole and this allows us to get a bound for the parameter. In a second step, we compute noncommutative corrections of the energy levels and find that they are at the second order in the parameter of noncommutativity. By comparing our results to those obtained from experimental spectroscopy, we get another limit for the parameter.Comment: 10 pages; no figures or table

Influence of Gravity on noncommutative Dirac equation

In this paper, we investigate the influence of gravity and noncommutativity on Dirac equation. By adopting the tetrad formalism, we show that the modified Dirac equation keeps the same form. The only modification is in the expression of the covariant derivative. The new form of this derivative is the product of its counterpart given in curved space-time with an operator which depends on the noncommutative $\theta$-parameter. As an application, we have computed the density number of the created particles in presence of constant strong electric field in an anisotropic Bianchi universe.Comment: 9 pages, correct some miprints, Accepted for publication in journal of Mod. Phys. Letters