arXiv subjects
Publications and source records attributed to Johannes M. Bauer.
Rare B decays permit stringent tests of the Standard Model and allow searches for new physics. Several rare radiative-decay studies of the B meson from the BaBar collaboration are described. So far no sign for new physics was discovered.
The electromagnetic calorimeter at the BaBar detector, part of the asymmetric B Factory at SLAC, measures photons in the energy range from 20 MeV to 8 GeV with high resolution. The current status of the calorimeter, now in its seventh year of operation, is being presented, as well as details on improvements made to the analysis code during the last years.
Electromagnetic radiative penguin decays of the B meson were studied with the BaBar detector at SLAC's PEP-II asymmetric-energy B Factory. Branching fractions and isospin asymmetry of the decay B -> K* gamma, branching fractions of B -> K2*(1430) gamma, and a search for B0 -> phi gamma are presented. The decay rates may be enhanced by contributions from non-standard model processes.
The electro-magnetic calorimeter at the BaBar detector, part of the asymmetric B Factory at SLAC, measures photons in the energy range from 20 MeV to 8 GeV with good resolution. The calorimeter is calibrated at the low energy end with 6.13 MeV photons obtained from a liquid source system. During the calibration, a fluorine-rich liquid is activated via a neutron generator and pumped past the front of the calorimeter's crystals. Decays that occur in front of the crystals emit photons of well-defined energy, which are detected in the crystals with the regular data acquisition system. The liquid source system adds only very little material in front of the calorimeter, needs nearly no maintenance, and allows operation at the switch of a key with minimal safety hazards. The report describes the system, presents calibration results obtained from its operation since 1999, shows the crystals' loss of light yield due to radiation damage, and shares experiences gained over the years.
This paper examines the effects of licensing conditions, in particular of spectrum fees, on the pricing and diffusion of mobile communications services. Seemingly exorbitant sums paid for 3G licenses in the UK, Germany in 2000 and similarly high fees paid by U.S. carriers in the re-auctioning of PCS licenses early in 2001 raised concerns as to the impacts of the market entry regime on the mobile communications market. The evidence from the GSM and PCS markets reviewed in this paper suggests that market entry fees do indeed influence the subsequent development of the market. We discuss three potential transmission channels by which license fees can influence the price and quantity of service sold in a wireless market: an increase in average cost, an increase in incremental costs, and impacts of sunk costs on the emerging market structure. From this conceptual debate, an empirical model is developed and tested using cross-sectional data for the residential mobile voice market. We utilize a structural equation approach, modeling the supply and demand relationships subject to the constraint that supply equals demand. The results confirm the existence of a positive effect of license fees on the cost of supply. However, we also find that higher market concentration has a positive effect on the overall supply in the market, perhaps supporting a Schumpeterian view that a certain degree of market concentration facilitates efficiency.
For the radiative Bhabha calibration of BaBar's electromagnetic calorimeter, the measured energy of a photon cluster is being compared with the energy obtained via a kinematic fit involving other quantities from that event. The details of the fitting algorithm are described in this note, together with its derivation and checks that ensure that the fitting routine is working properly.