A Twisted Custodial Symmetry in the Two-Higgs-Doublet Model

In the Standard Model for electroweak interactions, the Higgs sector is known to display a "custodial" symmetry protecting the mass relation m_{W^\pm}^2=m_{W_3}^2 from large corrections. When considering extensions of the scalar sector, this symmetry has to be introduced by hand in order to pass current electroweak precision tests in a natural way. In this Letter we implement a generalized custodial symmetry in the two-Higgs-doublet model. Assuming the invariance of the potential under CP transformations, we prove the existence of a new custodial scenario characterized by m_{H^\pm}^2=m_{H^0}^2 instead of m_{H^\pm}^2=m_{A^0}^2. Consequently the pseudoscalar A^0 may be much lighter than the charged H^\pm, giving rise to interesting phenomenology.Comment: 4 pages, RevTeX

The observable light deflection angle

The physical deflection angle of a light ray propagating in a space-time supplied with an asymptotically flat metric has to be expressed in terms of the impact parameter.Comment: 11 pages, 1 figur

A theoretical determination of the eta-eta' mixing

The systematic large N_c limit within chiral perturbation provides an optimal eta-eta' mixing angle of about -27 degrees at leading order in p^2. In this frame, agreement with the data can be reached with higher order corrections of about 20%.Comment: 12 pages, 2 figures; reference to the two-mixing-angle scheme added, minor corrections; to appear in JHE

Tests for the asymptotic behaviour of the gamma^* --> gamma pi^0 form factor

The gamma^* --> gamma pi^0 transition measured at different photon virtualities already provides us with a clean test for the behaviour of the pi^0 gamma^* gamma off-shell axial anomaly at large time-like squared momenta. It also allows reliable predictions for the branching ratio of heavy quarkonium decays into omega pi^0.Comment: Latex, 7 pages + 1 .ps figure, comments on the Brodsky-Lepage limit and 5 new references adde

A model for the dynamics of extensible semiflexible polymers

We present a model for semiflexible polymers in Hamiltonian formulation which interpolates between a Rouse chain and worm-like chain. Both models are realized as limits for the parameters. The model parameters can also be chosen to match the experimental force-extension curve for double-stranded DNA. Near the ground state of the Hamiltonian, the eigenvalues for the longitudinal (stretching) and the transversal (bending) modes of a chain with N springs, indexed by p, scale as lambda_lp ~ (p/N)^2 and lambda_tp ~ p^2(p-1)^2/N^4 respectively for small p. We also show that the associated decay times tau_p ~ (N/p)^4 will not be observed if they exceed the orientational time scale tau_r ~ N^3 for an equally-long rigid rod, as the driven decay is then washed out by diffusive motion.Comment: 28 pages, 2 figure

Assessing intonation skills in a tertiary music training programme

[Abstract]: Buttsworth, Fogarty, and Rorke (1993) reported the construction of a battery of tonal tests designed to assess intonation abilities. A subset of the tests in the battery predicted 36 per cent of final scores in an aural training subject in a tertiary music course. In the current study, the original battery of fourteen tests was reduced to six tests and administered three times throughout the academic year to a new sample (N = 87) of tertiary music students. Three research questions were investigated. Firstly, it was hypothesised that tests in the battery would discriminate among the different aural classes at USQ, which were grouped according to ability level. The results from discriminant function analyses provided strong support for this hypothesis. Secondly, it was hypothesised that students should improve their performance on the pitch battery across the three administrations. A repeated measures analysis of variance failed to find evidence of overall improvement. Finally, it was hypothesised that there would be significant differences on the intonation tests between musicians of different instrumental families. Again, no overall differences were found. The results indicated that intonation tests appear to tap an ability that (a) is not significantly modified by training, (b) is more or less the same across different instrument families, and (c) is related to success in music training programmes

TOP-INDUCED ELECTROWEAK BREAKING IN THE MINIMAL SUPERSYMMETRIC STANDARD MODEL

Severe constraints on parameters of the minimal supersymmetric standard model follow from a dynamical electroweak symmetry breaking mechanism dominated by top and stop loops. In particular, the lightest Higgs boson mass is expected to be smaller than 100 GeV.Comment: 10 pages, Latex, 6 Postcript Figure

Anomalous enhancement of a penguin hadronic matrix element in B->K eta'

We estimate the density matrix element for the pi^0, eta and eta' production from the vacuum in the large-N_c limit. As a consequence, we find that the QCD axial anomaly leads to highly non-trivial corrections to the usual flavour SU(3) relations between B^0-> K^0 pi^0, B^0-> K^0 eta and B^0-> K^0 eta' decay amplitudes. These corrections may explain why the B-> K eta' branching ratio is about six times larger than the B-> K pi one.Comment: 5 pages, 1 figur