Top-bottom mass hierarchy, s−μs-\mu puzzle and gauge coupling unification with split multiplets

A supersymmetric 5D SU(5) grand unification is considered. The SU(5) is broken down to $G_{SM}=SU(3)\times SU(2)\times U(1)$ by the $Z_2\times Z_2'$ assignment of the bulk field(s). The matter fields are located at the fixed point(s). In the bulk, a Higgs multiplet $\bar 5_H$(containing the bottom doublet $H_1$) and the SU(5) gauge multiplet are located. At one fixed point, $H_2$(the top doublet) and the standard model matter multiplets are presented. Because of the difference of the locations of $H_1$ and $H_2$, one can obtain a hierarchy between top and bottom Yukawa couplings. We also present a possibility to understand the $s-\mu$ mass puzzle in this framework of the split multiplet.Comment: LaTeX file of 17 pages including 3 eps figures. A note is added and typo errors corrected. To appear in Euro. Phys. J.

A reconnaissance of the possible donor stars to the Kepler supernova

The identity of Type Ia supernova progenitors remains a mystery, with various lines of evidence pointing towards either accretion from a non-degenerate companion, or the rapid merger of two degenerate stars leading to the thermonuclear destruction of a white dwarf. In this paper we spectroscopically scrutinize 24 of the brightest stars residing in the central 38" x 38" of the SN 1604 (Kepler) supernova remnant to search for a possible surviving companion star. We can rule out, with high certainty, a red giant companion star - a progenitor indicated by some models of the supernova remnant. Furthermore, we find no star that exhibits properties uniquely consistent with those expected of a donor star down to L>10Lsun. While the distribution of star properties towards the remnant are consistent with unrelated stars, we identify the most promising candidates for further astrometric and spectroscopic follow-up. Such a program would either discover the donor star, or place strong limits on progenitor systems to luminosities with L<<Lsun.Comment: accepted by Ap

Typification of names of Clusiaceae based on material collected by August Weberbauer in Peru

August Weberbauer was a German botanist who worked for most of his life in Peru. Many species have been described based on specimens collected by him, which were mainly deposited in the Berlin herbarium (B). After the bombing of the Berlin herbarium during World War II, it was assumed that most of these types had been destroyed, duplicates rarely existed and neotypes had to be designated. However, during visits to Peruvian herbaria we rediscovered some overlooked duplicates of specimens of Clusiaceae. In the present paper, we designate lectotypes of ten names based on these Weberbauer collections and report additional duplicates found in the herbarium G. Some former incorrect typifications are corrected, and the problem of destroyed types in herbarium B, often known mainly from photos made by J. F. Macbride, is briefly discussed.492193196CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP311744/2017-62012/51781-0; 2012/15542-

Silicon detectors for neutrino oscillation experiments

This note describes the technique of using a target equipped with high resolution silicon microstrip detectors for the detection of the topological signature of decays in neutrino oscillation ex periments. Two detectors are presented. The first detector is installed in the NOMAD spectrometer at the CERN SPS neutrino beam. The target consists of four layers passive boron carbide plate s (total mass of 45 kg) interleaved with five layers of silicon microstrip detectors. A total of 600 single--sided silicon microstrip detectors are used amounting to a total area of 1.14 m$^2$. The silicon tracker is made with the longest ladders built to date (72 cm). During the 1997 run about 8000 charged current interactions were estimated to have occurred in the target and data tak ing will continue in 1998. For these events it will be possible to perform a precise measurement of both vertex and kinematical variables. The second detector was installed in September 1997 in a CERN PS pion beam to investigate the possibility of combining silicon detectors and nuclear emulsions. This detector consists of 72 single--sided silicon microstrip detectors with a total surfac e of 0.13 m$^2$ distributed over four layers, providing two measurements of each of the two orthogonal coordinates. This exposure will measure the precision with which the silicon tracker can p redict the position of particles in the emulsion. Both detectors provide invaluable experience towards the construction of a large scale silicon tracker for future neutrino oscillation experime nts