118609457
Relativistic Landau-Aharonov-Casher quantization based on the Lorentz symmetry violation background
Based on the discussions about the Aharonov-Casher effect in the Lorentz symmetry violation background, we show that the analogue of the relativistic Landau quantization in the Aharonov-Casher setup can be achieved in the Lorentz-symmetry violation background.
119604866
Physical regularization for the spin-1/2 Aharonov-Bohm problem in conical space
We examine the bound state and scattering problem of a spin-one-half particle undergone to an Aharonov-Bohm potential in a conical space in the nonrelativistic limit. The crucial problem of the \delta-function singularity coming from the Zeeman spin interaction with the magnetic flux tube is solved through the self-adjoint extension method. Using two different approaches already known in the literature, both based on the self-adjoint extension method, we obtain the self-adjoint extension parameter to the bound state and scattering scenarios in terms of the physics of the problem. It is shown that such a parameter is the same for both situations. The method is general and is suitable for any quantum system with a singular Hamiltonian that has bound and scattering states.
119322655
Finiteness of the noncommutative supersymmetric Maxwell-Chern-Simons theory
Within the superfield approach, we prove the absence of UV/IR mixing in the three-dimensional noncommutative supersymmetric Maxwell-Chern-Simons theory at any loop order and demonstrate its finiteness in one, three, and higher loop orders.
119697349
On the spin- 1/2 Aharonov-Bohm problem in conical space: Bound states, scattering and helicity nonconservation
In this work the bound state and scattering problems for a spin-1/2 particle undergone to an Aharonov-Bohm potential in a conical space in the nonrelativistic limit are consider ed. The presence of a �-function singularity, which comes from the Zeeman spin interaction with the magnetic flux tube, is addressed by the self-adjoint extension method. One of the advantages of the present approach is the determination of the self-adjoint extension parameter in terms of physics of the problem. Expressions for the energy bound states, phase-shift and S matrix are determined in terms of the self-adjoint extension parameter, which is explicitly determined in terms of the parameters of the problem. The relation between the bound state and zero modes and the failure of helicity conservation in the scattering problem and its relation with the gyromagnetic ratio g are discussed. Also, as an application, we consider the spin-1/2 AharonovBohm problem in conical space plus a two-dimensional isotropic harmonic oscillator.
122063121
Relativistic Anandan quantum phase in the Lorentz violation background
We study the influence of a classical background based on the violation of the Lorentz symmetry on the relativistic Anandan quantum phase. We show that the choice of the Lorentz symmetry violation background provides an abelian contribution for the relativistic Anandan quantum phase.
118364878
On the superfield effective potential in three dimensions
We develop the superfield approach to the effective potential in three dimensions and calculate the one-loop and two-loop Kahlerian effective potential in commutative and noncommutative cases.
56132160
Search for the minimal standard model Higgs boson
A search for the Minimal Standard Model Higgs boson (H0) has been performed with data from e+e− collisions collected by the OPAL detector at LEP. The search was made for events of the types e+e−→(e+e−,μ+μ− or νν)H0, H0→qq and was based on approximately 78 pb−1 of data taken at center-of-mass energies between 88 and 95 GeV in the years 1990–1993. The present study, combined with previous OPAL publications, excludes the existence of a Minimal Standard Model Higgs boson with mass below 56.9 GeV at the 95% confidence level.
116534437
An improved measurement of R-b using a double tagging method
62820113
THE COMPACT EMULSION SPECTROMETER
Abstract An emulsion spectrometer has been built and tested with pion beams in a 0.7 T magnetic field. A momentum resolution, ΔP/P=13%±1%, has been obtained for 5 and 10 GeV /c particles.
117606624
The Build‐up of Opacity in Impulsive Relativistic Sources
Opacity effects in relativistic high‐energy γ‐ray sources, such as γ‐ray bursts (GRBs) or Blazars, can probe the Lorentz factor of the outflow and the distance of the emission site from the source, and thus help constrain the composition of the outflow (protons, pairs, magnetic field) and the emission mechanism. While most previous works consider the opacity in steady state, we study the effects of the time dependence of the opacity to pair production (γγ → e+e−) in an impulsive relativistic source. This may be relevant for the prompt γ‐ray emission in GRBs or flares in Blazars. We present a simple, yet rich, semi‐analytic model for the time and energy dependence of the optical depth, τγγ, in which a thin spherical shell expands ultra‐relativistically and emits isotropically in its own rest frame over a finite range of radii, R0 ⩽ R ⩽ R0 + ΔR. This is particularly relevant for GRB internal shocks. We find that in an impulsive source (ΔR ≲ R0), while the instantaneous spectrum (which is typically hard to m...
120356698
A study of two-particle momentum correlations in hadronic Z0 decays
Abstract We report on a measurement of two-particle momentum correlations in hadronic decays of the Z 0 at LEP. These data are compared with recent analytic QCD calculations based on the summation of leading and next-to-leading logarithms, and with QCD Monte Carlo simulations. We find that the analytic calculations show the same general features as the data, but that the overall level of the correlations is not reproduced, suggesting that higher order or hadronization effects are significant. This contrasts with the success of similar QCD calculations in describing single-particle momentum distributions. QCD Monte Carlo models are found to give a reasonable level of correlation, with parton shower models incorporating string hadronization giving the best description of the data.