A CoGeNT confirmation of the DAMA signal

The CoGeNT collaboration has recently reported a rising low energy spectrum in their ultra low noise germanium detector. This is particularly interesting as the energy range probed by CoGeNT overlaps with the energy region in which DAMA has observed their annual modulation signal. We show that the mirror dark matter candidate can simultaneously explain both the DAMA annual modulation signal and the rising low energy spectrum observed by CoGeNT. This constitutes a model dependent confirmation of the DAMA signal and adds weight to the mirror dark matter paradigm.Comment: About 8 pages, expanded and update

Primordial He' abundance implied by the mirror dark matter interpretation of the DAMA/Libra signal

We compute the primordial mirror helium He' mass fraction emerging from Big Bang nucleosynthesis in the mirror sector of particles in the presence of kinetic mixing between photons and mirror photons. We explore the kinetic mixing parameter (epsilon) values relevant for cosmology and which are also currently probed by the dark matter direct detection experiments. In particular, we find that for epsilon \sim 10^{-9}, as suggested by the DAMA/Libra and other experiments, a large He' mass fraction (Y_{He'} \approx 90%) is produced. Such a large value of the primordial He' mass fraction will have important implications for the mirror dark matter interpretation of the direct detection experiments, as well as for the study of mirror star formation and evolution.Comment: 8 pages, 1 figur

Evolutionary and structural properties of mirror star MACHOs

There can exist a hidden sector of the Universe in the form of parallel ''mirror'' world which has the same particle physics as the observable world and interacts with the latter only gravitationally. Big Bang Nucleosynthesis bounds demand that the mirror sector should have a smaller temperature than the ordinary one. This implies that the mirror matter could play a role of dark matter, and in addition its chemical content should be dominated by helium. Here we study the evolutionary and structural properties of the mirror stars which essentially are similar to that of the ordinary stars but with higher helium contents. Being invisible in terms of photons, they could be observed only as MACHOs in the microlensing experiments. Using a numerical code, we compute evolution of stars with large helium abundances (Y = 0.30-0.80) and a wide range of masses, from 0.5 to 10 solar masses. We found that helium dominated mirror star should have much faster evolutionary time (up to a factor 30) than the ordinary star with the same mass. In addition, we show the diagrams of luminosities, effective temperatures, central temperatures and densities, and compute the masses of the He core at ignition and the minimum mass for carbon ignition, for different chemical compositions. The general conclusion is that mirror stars evolve faster as compared to ordinary ones, and explode earlier as type II supernovae, thus enriching the galactic halo of processed mirror gas with higher metallicity, with implications for MACHO observations and galaxy evolution.Comment: 24 pages, 10 figures; minor change

An alternative SU(4) x SU(2)L x SU(2)R model

A simple alternative to the usual Pati-Salam model is proposed. The model allows quarks and leptons to be unified with gauge group $SU(4) \otimes SU(2)_L \otimes SU(2)_R$ at a remarkably low scale of about 1 TeV. Neutrino masses in the model arise radiatively and are naturally light.Comment: 9 pages, Latex (1 Figure

Are four neutrino models ruled out?

We show explicitly that four neutrino models of the 2+2 variety still provide an acceptable global fit to the solar, atmospheric and LSND neutrino data. The goodness of fit, defined in the usual way, is found to be 0.26 for the simplest such model. That is, we find that there is a 26% probability of obtaining a worse global fit to the neutrino data We also make some specific comments on the paper, ``Ruling out four-neutrino oscillation interpretations of the LSND anomaly'' [hep-ph/0207157], and explain why they reached drastically different conclusions.Comment: about 4 page

Training for preservation management

In August 1997 the first of a series of summer schools in Preservation Management was held at the Archivschule in Marburg (Germany). The school was organised by the ECPA, the LIBER Division on Preservation, ICA and the Archivschule itself and was aimed at archivists and librarians in management positions from European institutions. It dealt with managerial, organisational and financial aspects of preservation and required active participation by those attending. Apart from introductory sessions by the teaching staff at the Archivschule, a large part of the course took the form of working groups, discussions, assignments and role play, to which participants were expected to take their own experience and problems. The school was conducted in German. Topics, spread over five days, ranged from preservation in the context of the core activities of libraries and archives; planning of preservation projects; general management issues, such as resource management, budgeting, priority setting, communication and effecting change; to more detailed considerations of day-to-day issues, such as storage, disaster control, microfilming and digitising, mass conservation processes, and moulds and fungi

Some comments on Super-Kamiokande's multi-ring analysis

The super-Kamiokande collaboration have used multi-ring events to discriminate between the $\nu_\mu --> \nu_\tau$ and $\nu_\mu --> \nu_s$ solutions to the atmospheric neutrino anomaly. We show that the effect of systematic uncertainties in cross sections are so significant that the usefulness of multi-ring data to distinguish between these two solutions is doubtful.Comment: About 8 pages lon

Maximal νe→νs\nu_e \to \nu_s solution to the solar neutrino problem: just-so, MSW or energy independent?

We examine the maximal $\nu_e \to \nu_s$ solution to the solar neutrino problem. This solution can be motivated by the exact parity model and other theories. The $\nu_e$ survival probability exhibits one of three qualitatively different behaviours depending on the value of $\Delta m^2$, viz. approximately energy independent, just-so or MSW. By the last of these we mean an enhanced night-time event rate due to regeneration in the Earth. We study all of these possibilities in the context of the recent SuperKamiokande data.Comment: minor changes to text and fig.