No abstract

We consider quantum effects in a world with two coexisting symmetry phases, unbroken and spontaneously broken, as a result of a first order phase transition. The discrete symmetries of the problem are discussed in general. We compute the exact twopoint Green function for a free fermion, when a thin wall separates the two phases. The Dirac propagator displays both massive and massless poles, and new CP-even phases resulting from the fermion reflection on the wall. We discuss the possible quarkantiquark CP asymmetries produced in the Standard Model(SM) for the academic T = 0 case. General arguments indicate that an effect first appears at order α W in the reflection amplitude, as the wall acts as a source of momentum and the on-shell one-loop self-energy cannot be renormalized away. The asymmetries stem from the interference of the SM CP-odd couplings and the CP-even phases in the propagator. We perform a toy computation that indicates the type of GIM cancellations of the problem. The behaviour can be expressed in terms of two unitarity triangles.

No abstract

This paper describes the silicon microstrip modules in the barrel section of the SemiConductor Tracker (SCT) of the ATLAS experiment at the CERN Large Hadron Collider (LHC). The module requirements, components and assembly techniques are given, as well as first results of the module performance on the fully-assembled barrels that make up the detector being installed in the ATLAS experiment.