Relating Neutrino Masses by dilepton modes of Doubly Charged Scalars

We study a model with Majorana neutrino masses generated through doubly charged scalars at two-loop level. We give explicit relationships between the neutrino masses and the same sign dilepton decays of the doubly charged scalars. In particular, we demonstrate that at the tribimaximal limit of the neutrino mixings, the absolute neutrino masses and Majorana phases can be extracted through the measurements of the dilepton modes at colliders.Comment: 14 pages, 8 figures, references added, version to be published in PR

AN ASSESSMENT OF THE RECREATIONAL AND COMMERCIAL SKIBOAT FISHERY IN THE TRANSKEI

A survey of the recreational and commercial skiboat linefishery in the Transkei was conducted from March 1997 to April 1999. Effort by commercial skiboats was substantially higher than by recreational skiboats, and catch rates on commercial boats were much higher than rates on recreational boats. Catch rates in the region were not greater than those in the adjoining provinces of KwaZulu-Natal and the Eastern Cape, but the mean size of fish caught on commercial skiboats in the southern Transkei was larger than that in either KwaZulu-Natal or the Eastern Cape. Total annual commercial catches estimated for the Transkei were substantially greater than those based on returns submitted by skippers to the National Marine Linefish System. Catches in the northern Transkei were more diverse than in the south, and catches from both regions contained a large number of endemic species. Northern Transkei catches were characterized by subtropical species, whereas those from the southern Transkei contained more warm-temperate species. In the northern region, subtropical species replaced warmtemperate ones during winter. Knowledge of fishing regulations by fishers was reasonable, but compliance was poor, mainly as a result of the low level of enforcement of regulations in this region, which needs to be improved if catches are to be sustained. Among other recommendations, the establishment of an effective marine reserve in the area is a priority; it would assist with the conservation of several species of endemic linefish.Afr. J. mar. Sci. 25: 61–7

Quark-lepton mass unification at TeV scales

A scenario combining a model of early (TeV) unification of quarks and leptons with the physics of large extra dimensions provides a natural mechanism linking quark and lepton masses at TeV scale. This has been dubbed as early quark-lepton mass unification by one of us (PQH) in one of the two models of early quark-lepton unification, which are consistent with data, namely SU(4)_PS \otimes SU(2)_L \otimes SU(2)_R \otimes SU(2)_H. In particular, it focused on the issue of naturally light Dirac neutrino. The present paper will focus on similar issues in the other model, namely SU(4)_PS \otimes SU(3)_L \otimes SU(3)_H.Comment: Accepted for publication in PRD: The new version is in agreement with the accepted manuscrip

ASSESSMENT OF THE LINEFISHERY IN TWO URBAN ESTUARINE SYSTEMS IN KWAZULU-NATAL, SOUTH AFRICA

The recreational linefisheries in Durban Harbour and the Mgeni Estuary were surveyed using roving creel and access-point surveys during the period January–December 2000. In total, 3 351 shore-anglers and 652 boat-anglers were checked for catch-and-effort information, and 432 shore-anglers were interviewed using a demographic and socio-economic questionnaire. Durban Harbour had much higher angling effort than the Mgeni Estuary. Angling activity was higher on weekends (121 and 23 anglers per count for the harbour and Mgeni Estuary respectively) than during the week (34 and 9 anglers per count respectively). Total effort expended in Durban Harbour and the Mgeni Estuary shore-fisheries during 2000 was estimated to be 54 024 and 11 977 angler-outings respectively. Annual effort for the Durban Harbour boat-fishery for the same period was estimated to be 9 991 angler-outings. The flathead mullet Mugil cephalus was the most commonly harvested species in both Durban Harbour and the Mgeni Estuary shore-fisheries (25.2 and 68.1&#37 respectively), and spotted grunter Pomadasys commersonnii (41.5&#37) was the most commonly harvested species in the Durban Harbour boat-fishery. Because of their small size, a large proportion (>63&#37) of the total fish catch at both localities was released. Mean catch per unit effort for the Durban Harbour boat-based fishery (0.11 fish angler-1 h-1 or 0.15 kg angler-1 h-1) was higher than that of the shore-based fishery (0.071 fish angler-1 h-1 or 0.034 kg angler-1 h-1). The questionnaire survey indicated that anglers had high site fidelity, considerable years of fishing experience (mean of 17.2 years for the harbour, 13.6 years for Mgeni) and high compliance with possession of fishing permits (86&#37 harbour, 84&#37 Mgeni). Although anglers generally supported the regulations currently applicable to the linefishery (>71&#37 harbour, >77&#37 Mgeni), the questionnaire results showed that specific nowledge for target species was poor (45–70&#37 harbour, 29–60&#37 Mgeni). The level of fisheries law enforcement (6.4&#37 of harbour outings inspected, 7&#37 Mgeni outings inspected) was poorer than in the previously studied KwaZulu-Natal marine shorefishery. Economic investment by participants in terms of angling equipment used in the shore-fisheries of the two systems was calculated to be &#62 R10 million, and expenditure in terms of bait, travel and tackle costs was approximately R9 million per year.Afr. J. mar. Sci. 25: 111–13

EVALUATION OF PARTICIPATION IN AND MANAGEMENT OF THE TRANSKEI SHORE LINEFISHERY

Both roving creel and aerial surveys were used to quantify fishing effort along the former Transkei coast. A stratified random sampling procedure was used during shore patrols to assess catch and effort, and a questionnaire survey provided information on total fishing effort, fisher demographics and attitudes towards current regulations. A total of 13 field trips was undertaken, during which 341 fishers were interviewed and the catches of 760 fishers examined. In all, 175 patrols were undertaken, covering in all 1 117 km. Some 24 random aerial counts of shore-fishers were also carried out during the study. From the aerial surveys, average fisher density along the Transkei coast was estimated at 0.79 fishers km-1, with an estimated total fishing effort of 170 457 fisher-days year-1. Fisher densities were highest in spring (0.9 fishers km-1) and lowest during summer (0.5 fishers km-1). Fishers were most successful in winter (1.0 fish fisher-1 inspection-1) and least successful in summer (0.4 fish fisher-1 inspection-1). Catch rates amounted to 1.4 fish fisher-1 day-1, or 0.86 kg fisher-1 day-1, and the total catch was estimated at 147 tons year-1. The main target species were bronze bream Pachymetopon grande (22&#37), blacktail Diplodus sargus capensis (19&#37) and dusky kob Argyrosomus japonicus (18&#37). Numerically, the most important species in the catches were elf Pomatomus saltatrix (18&#37) and blacktail (16&#37). By mass, the most important species were bronze bream (26&#37) and dusky kob (18&#37). Knowledge and compliance of regulations currently governing the linefishery in the Transkei was exceptionally poor, although most fishers supported the principle of regulations. Better-enforced and larger marine protected areas, establishment of a fisher awareness programme and improved enforcement of fishing regulations are suggestions for improving the current management of the Transkei shore-fishery.Afr. J. mar. Sci. 25: 79–9

Fermions Tunnelling from Black Holes

We investigate the tunnelling of spin 1/2 particles through event horizons. We first apply the tunnelling method to Rindler spacetime and obtain the Unruh temperature. We then apply fermion tunnelling to a general non-rotating black hole metric and show that the Hawking temperature is recovered.Comment: 22 pages, v2: added references, v3: fixed minor typos, v4: added a new section applying fermion tunnelling method to Kruskal-Szekers coordinates, fixed minor typo, and added references, v5: modified introduction and conclusion, fixed typo

Hawking radiation of Dirac particles via tunneling from Kerr black hole

We investigated Dirac Particles' Hawking radiation from event horizon of Kerr black hole in terms of the tunneling formalism. Applying WKB approximation to the general covariant Dirac equation in Kerr spacetime background, we obtain the tunneling probability for fermions and Hawking temperature of Kerr black hole. The result obtained by taking the fermion tunneling into account is consistent with the previous literatures.Comment: 7 pages, no figures, to appear in CQ

On Neutrino Masses and Family Replication

The old issue of why there are more than one family of quarks and leptons is reinvestigated with an eye towards the use of anomaly as a tool for constraining the number of families. It is found that, by assuming the existence of right-handed neutrinos (which would imply that neutrinos will have a mass) and a new chiral SU(2) gauge theory, strong constraints on the number of families can be obtained. In addition, a model, based on that extra SU(2), is constructed where it is natural to have one "very heavy" fourth neutrino and three almost degenerate light neutrinos whose masses are all of the Dirac type.Comment: RevTex, 12 pages with 1 figure, minor changes to the text and added acknowledgment

Gauss-Bonnet Black Holes and Heavy Fermion Metals

We consider charged black holes in Einstein-Gauss-Bonnet Gravity with Lifshitz boundary conditions. We find that this class of models can reproduce the anomalous specific heat of condensed matter systems exhibiting non-Fermi-liquid behaviour at low temperatures. We find that the temperature dependence of the Sommerfeld ratio is sensitive to the choice of Gauss-Bonnet coupling parameter for a given value of the Lifshitz scaling parameter. We propose that this class of models is dual to a class of models of non-Fermi-liquid systems proposed by Castro-Neto et.al.Comment: 17 pages, 6 figures, pdfLatex; small corrections to figure 10 in this versio

Lepton Flavor Violation in Predictive Supersymmetric GUT Models

There have been many theoretical models constructed which aim to explain the neutrino masses and mixing patterns. While many of the models will be eliminated once more accurate determinations of the mixing parameters, especially $\sin^2 2\theta_{13}$, are obtained, charged lepton flavor violation (LFV) experiments are able to differentiate even further among the models. In this paper, we investigate various rare LFV processes, such as $\ell_{i} \to \ell_{j} + \gamma$ and $\mu-e$ conversion, in five predictive supersymmetric (SUSY) SO(10) models and their allowed soft-SUSY breaking parameter space in the constrained minimal SUSY standard model. Utilizing the Wilkinson Microwave Anisotropy Probe dark matter constraints, we obtain lower bounds on the branching ratios of these rare processes and find that at least three of the five models we consider give rise to predictions for $\mu \to e + \gamma$ that will be tested by the MEG Collaboration at PSI. In addition, the next generation $\mu-e$ conversion experiment has sensitivity to the predictions of all five models, making it an even more robust way to test these models. While generic studies have emphasized the dependence of the branching ratios of these rare processes on the reactor neutrino angle $\theta_{13}$ and the mass of the heaviest right-handed neutrino $M_3$, we find very massive $M_3$ is more significant than large $\theta_{13}$ in leading to branching ratios near to the present upper limits.Comment: Published version: 25 pages including 11 figures; acknowledgment, references, and note added with minor changes from v