arXiv subjects

J. P. Silva

Publications and source records attributed to J. P. Silva.

6 recordsLinked to original sources

arXiv2011

A soft origin for CKM-type CP violation

We present a two-Higgs-doublet model, with a $\mathbbm{Z}_3$ symmetry, in which CP violation originates solely in a soft (dimension-2) coupling in the scalar potential, and reveals itself solely in the CKM (quark mixing) matrix. In particular, in the mass basis the Yukawa interactions of the neutral scalars are all real. The model has only eleven parameters to fit the six quark masses and the four independent CKM-matrix observables. We find regions of parameter space in which the flavour-changing neutral couplings are so suppressed that they allow the scalars to be no heavier than a few hundred GeV.

hep-ph↗

arXiv2006

Comparing a current-carrying circular wire with polygons of equal perimeter; Magnetic field versus magnetic flux

We compare the magnetic field at the center of and the self-magnetic flux through a current-carrying circular loop, with those obtained for current-carrying polygons with the same perimeter. As the magnetic field diverges at the position of the wires, we compare the self-fluxes utilizing several regularization procedures. The calculation is best performed utilizing the vector potential, thus highlighting its usefulness in practical applications. Our analysis answers some of the intuition challenges students face when they encounter a related simple textbook example. These results can be applied directly to the determination of mutual inductances in a variety of situations.

physics.ed-ph↗

arXiv2005

Reparametrization invariance of B decay amplitudes and implications for new physics searches in B decays

When studying B decays within the Standard Model, it is customary to use the unitarity of the CKM matrix in order to write the decay amplitudes in terms of only two of the three weak phases which appear in the various diagrams. Occasionally, it is mentioned that those two weak phases can be used in order to describe any decay amplitude, even beyond the Standard Model. Here we point out that, when describing a generic decay amplitude, the two weak phases can be chosen completely at will, and we study the behavior of the decay amplitudes under changes in the two weak phases chosen as a basis. Of course, physical observables cannot depend on such reparametrizations. This has an impact in discussions of the SM and in attempts to parametrize new physics effects in the decay amplitudes. We illustrate these issues by looking at B --> psi K_S and the isospin analysis in B --> pi pi.

hep-ph↗

arXiv2002

B Physics at the Tevatron: Run II and Beyond

This report provides a comprehensive overview of the prospects for B physics at the Tevatron. The work was carried out during a series of workshops starting in September 1999. There were four working groups: 1) CP Violation, 2) Rare and Semileptonic Decays, 3) Mixing and Lifetimes, 4) Production, Fragmentation and Spectroscopy. The report also includes introductory chapters on theoretical and experimental tools emphasizing aspects of B physics specific to hadron colliders, as well as overviews of the CDF, D0, and BTeV detectors, and a Summary.

hep-ph↗

arXiv1995

Constraining new interactions with leptonic tau decays

The recent measurements of the Michel parameters in tau decays enable, for the first time, a thorough analysis of the leptonic sector. In general, in models beyond the Standard Model, these parameters will be altered through changes in the W and Z couplings, and/or through interactions mediated by new gauge bosons. We perform a complete, model independent analysis of the constraints imposed by the present data on such boson-mediated interactions, and point out the existence of useful relations among the couplings.

hep-ph↗

arXiv1993

Quantum Statistical Metastability Revisited

We calculate the decay rate for a state prepared in a thermal density matrix centered on a metastable ground state. We find a rate that is intrinsically time {\it dependent}, as opposed to the {\it constant} rates of previous works. The rate vanishes at early times, rises to a maximum and eventually falls-off to zero as a consequence of unitary time evolution. Finally, we discuss extensions of this calculation to field theories and possible implications for both sphaleron mediated transitions and first order inflationary theories.

hep-ph↗