No Arabic abstract
We consider a higher derivative effective theory for an Abelian gauge field in three dimensions, which represents the result of integrating out heavy matter fields interacting with a classical gauge field in a parity-conserving way. We retain terms containing up to two derivatives of $F_{mu u}$, but make no assumption about the strength of this field. We then quantize the gauge field, and compute the one-loop effective action for a constant $fmn$. The result is explicitly evaluated for the case of a constant magnetic field.
We present some results about the interplay between the chiral and deconfinement phase transitions in parity-conserving QED3 (with N flavours of massless 4 component fermions) at finite temperature. Following Grignani et al (Phys. Rev. D53, 7157 (1996), Nucl. Phys. B473, 143 (1996)), confinement is discussed in terms of an effective Sine-Gordon theory for the timelike component of the gauge field A_0. But whereas in the references above the fermion mass m is a Lagrangian parameter, we consider the m=0 case and ask whether an effective S-G theory can again be derived with m replaced by the dynamically generated mass Sigma which appears below T_{ch}, the critical temperature for the chiral phase transition. The fermion and gauge sectors are strongly interdependent, but as a first approximation we decouple them by taking Sigma to be a constant, depending only on the constant part of the gauge field. We argue that the existence of a low-temperature confining phase may be associated with the generation of Sigma; and that, analogously, the vanishing of Sigma for T > T_{ch} drives the system to its deconfining phase. The effect of the gauge field dynamics on mass generation is also indicated. (38kb)
We evaluate the fermion propagator in parity-conserving QED_3 with N flavours, in the context of an IR domain approximation. This provides results which are non-perturbative in the loopwise expansion sense. We include fermion-loop effects, and show that they are relevant to the chiral symmetry breaking phenomenon, that can be understood in this context.
We review the current strategies to search for generic SUSY models with R-parity conservation in the ATLAS and CMS detectors at the LHC. The discovery reach in early data will be presented for the different search channels based on missing transverse momentum from undetected neutralinos and multiple jets. We will also describe the search for models of gauge-mediated supersymmetry breaking for which the NLSP is a neutralino decaying to a photon and a gravitino. Finally, we will present recent work on techniques used to reconstruct the decays of SUSY particles at the LHC in early data, based on the selection of final-state exclusive decay chains.
We consider a pionless effective theory with dibaryon fields for the description of the weak process involving two nucleons. We construct leading order Lagrangians that contain nucleon-dibaryon weak coupling constants. We calculate the physical observable in the photodisintegration of the deuteron at threshold and obtain the result in terms of the nucleon-dibaryon weak coupling constants. Relation to existing calculations is discussed.
We extend the Zee model, where tiny neutrino masses are generated at the one loop level, to a supersymmetric model with R-parity conservation. It is found that the neutrino mass matrix can be consistent with the neutrino oscillation data thanks to the nonholomorphic Yukawa interaction generated via one-loop diagrams of sleptons. We find a parameter set of the model, where in addition to the neutrino oscillation data, experimental constraints from the lepton flavor violating decays of charged leptons and current LHC data are also satisfied. In the parameter set, an additional CP-even neutral Higgs boson other than the standard-model-like one, a CP-odd neutral Higgs boson, and two charged scalar bosons are light enough to be produced at the LHC and future lepton colliders. If the lightest charged scalar bosons are mainly composed of the SU(2)_L-singlet scalar boson in the model, they would decay into e nu and mu nu with 50% of a branching ratio for each. In such a case, the relation among the masses of the charged scalar bosons and the CP-odd Higgs in the minimal supersymmetric standard model approximately holds with a radiative correction. Our model can be tested by measuring the specific decay patterns of charged scalar bosons and the discriminative mass spectrum of additional scalar bosons.