Stochastic background of gravitational waves

A continuous stochastic background of gravitational waves (GWs) for burst sources is produced if the mean time interval between the occurrence of bursts is smaller than the average time duration of a single burst at the emission, i.e., the so called duty cycle must be greater than one. To evaluate the background of GWs produced by an ensemble of sources, during their formation, for example, one needs to know the average energy flux emitted during the formation of a single object and the formation rate of such objects as well. In many cases the energy flux emitted during an event of production of GWs is not known in detail, only characteristic values for the dimensionless amplitude and frequencies are known. Here we present a shortcut to calculate stochastic backgrounds of GWs produced from cosmological sources. For this approach it is not necessary to know in detail the energy flux emitted at each frequency. Knowing the characteristic values for the ``lumped'' dimensionless amplitude and frequency we show that it is possible to calculate the stochastic background of GWs produced by an ensemble of sources.Comment: 6 pages, 4 eps figures, (Revtex) Latex. Physical Review D (in press

Implications of Space-Time foam for Entanglement Correlations of Neutral Kaons

The role of $CPT$ invariance and consequences for bipartite entanglement of neutral (K) mesons are discussed. A relaxation of $CPT$ leads to a modification of the entanglement which is known as the $\omega$ effect. The relaxation of assumptions required to prove the $CPT$ theorem are examined within the context of models of space-time foam. It is shown that the evasion of the EPR type entanglement implied by $CPT$ (which is connected with spin statistics) is rather elusive. Relaxation of locality (through non-commutative geometry) or the introduction of decoherence by themselves do not lead to a destruction of the entanglement. So far we find only one model which is based on non-critical strings and D-particle capture and recoil that leads to a stochastic contribution to the space-time metric and consequent change in the neutral meson bipartite entanglement. The lack of an omega effect is demonstrated for a class of models based on thermal like baths which are generally considered as generic models of decoherence

Renormalization of Hamiltonian Field Theory; a non-perturbative and non-unitarity approach

Renormalization of Hamiltonian field theory is usually a rather painful algebraic or numerical exercise. By combining a method based on the coupled cluster method, analysed in detail by Suzuki and Okamoto, with a Wilsonian approach to renormalization, we show that a powerful and elegant method exist to solve such problems. The method is in principle non-perturbative, and is not necessarily unitary.Comment: 16 pages, version shortened and improved, references added. To appear in JHE

Large area black body source for ITER ECE in situ calibration

Development and testing of a hot calibration source for the ECE systems on ITER is underway. The source is intended to meet the requirements described in DDD55 Overview of Diagnostics. The requirement is for two 200 mm diameter sources. One will operate at atmospheric pressure and be well removed from the experiment. The other will operate in vacuum near the plasma. Both will operate at temperatures up to 800 °C. Here we report on the development of a prototype hot calibration source and of a realistic thermal model of the hot calibration source that will be used in simulations of the thermal properties of the source. Selection of a reliable heating method is challenging. Heating methods under consideration will be discussed.Center for Electromechanic

Radiative Decay of a Long-Lived Particle and Big-Bang Nucleosynthesis

The effects of radiatively decaying, long-lived particles on big-bang nucleosynthesis (BBN) are discussed. If high-energy photons are emitted after BBN, they may change the abundances of the light elements through photodissociation processes, which may result in a significant discrepancy between the BBN theory and observation. We calculate the abundances of the light elements, including the effects of photodissociation induced by a radiatively decaying particle, but neglecting the hadronic branching ratio. Using these calculated abundances, we derive a constraint on such particles by comparing our theoretical results with observations. Taking into account the recent controversies regarding the observations of the light-element abundances, we derive constraints for various combinations of the measurements. We also discuss several models which predict such radiatively decaying particles, and we derive constraints on such models.Comment: Published version in Phys. Rev. D. Typos in figure captions correcte

Material screening and selection for XENON100

Results of the extensive radioactivity screening campaign to identify materials for the construction of XENON100 are reported. This Dark Matter search experiment is operated underground at Laboratori Nazionali del Gran Sasso (LNGS), Italy. Several ultra sensitive High Purity Germanium detectors (HPGe) have been used for gamma ray spectrometry. Mass spectrometry has been applied for a few low mass plastic samples. Detailed tables with the radioactive contaminations of all screened samples are presented, together with the implications for XENON100.Comment: 8 pages, 1 figur

The Ties that Double Bind Us: Career, Emotion and Narrative Coping in Difficult Working Relationships

This article examines through an autoethnographic account how career aspirations and constraints may lead individuals to endure emotionally aversive situations. It presents evidence that individuals in such situations engage in emotion‐focused coping through narrative, illustrated by the author’s autoethnographic narrative of a difficult working relationship which developed into a double bind situation. The paper suggests that narrative coping in response to a double bind can actually serve to reify and prolong such situations. The paper concludes that autoethnographic research does not lend itself to simple organisational solutions. Possible avenues for further research are outlined and discussed

A CsI(Tl) Scintillating Crystal Detector for the Studies of Low Energy Neutrino Interactions

Scintillating crystal detector may offer some potential advantages in the low-energy, low-background experiments. A 500 kg CsI(Tl) detector to be placed near the core of Nuclear Power Station II in Taiwan is being constructed for the studies of electron-neutrino scatterings and other keV-MeV range neutrino interactions. The motivations of this detector approach, the physics to be addressed, the basic experimental design, and the characteristic performance of prototype modules are described. The expected background channels and their experimental handles are discussed.Comment: 34 pages, 11 figures, submitted to Nucl. Instrum. Method

About Bianchi I with VSL

In this paper we study how to attack, through different techniques, a perfect fluid Bianchi I model with variable G,c and Lambda, but taking into account the effects of a $c$-variable into the curvature tensor. We study the model under the assumption,div(T)=0. These tactics are: Lie groups method (LM), imposing a particular symmetry, self-similarity (SS), matter collineations (MC) and kinematical self-similarity (KSS). We compare both tactics since they are quite similar (symmetry principles). We arrive to the conclusion that the LM is too restrictive and brings us to get only the flat FRW solution. The SS, MC and KSS approaches bring us to obtain all the quantities depending on \int c(t)dt. Therefore, in order to study their behavior we impose some physical restrictions like for example the condition q<0 (accelerating universe). In this way we find that $c$ is a growing time function and Lambda is a decreasing time function whose sing depends on the equation of state, w, while the exponents of the scale factor must satisfy the conditions $\sum_{i=1}^{3}\alpha_{i}=1$ and $\sum_{i=1}^{3}\alpha_{i}^{2}<1,$ $\forall\omega$, i.e. for all equation of state$,$ relaxing in this way the Kasner conditions. The behavior of $G$ depends on two parameters, the equation of state $\omega$ and $\epsilon,$ a parameter that controls the behavior of $c(t),$ therefore $G$ may be growing or decreasing.We also show that through the Lie method, there is no difference between to study the field equations under the assumption of a $c-$var affecting to the curvature tensor which the other one where it is not considered such effects.Nevertheless, it is essential to consider such effects in the cases studied under the SS, MC, and KSS hypotheses.Comment: 29 pages, Revtex4, Accepted for publication in Astrophysics & Space Scienc