358 research outputs found
Artificially induced positronium oscillations in a two-sheeted spacetime: consequences on the observed decay processes
Following recent theoretical results, it is suggested that positronium (Ps)
might undergo spontaneous oscillations between two 4D spacetime sheets whenever
subjected to constant irrotational magnetic vector potentials. We show that
these oscillations that would come together with o-Ps/p-Ps oscillations should
have important consequences on Ps decay rates. Experimental setup and
conditions are also suggested for demonstrating in non accelerator experiments
this new invisible decay mode.Comment: 9 pages, 2 figures. Minor form correction. Accepted for publication
in Int. J. of Modern Physics
A new experiment to search for the invisible decay of the orthopositronium
We propose an experiment to search for invisible decays of orthopositronium
(o-Ps) with a 90% confidence sensitivity in the branching ratio as low as
. Evidence for this decay mode would unambigously signal new physics:
either the existence of extra--dimensions or fractionally charged particles or
new light gauge bosons. The experimental approach and the detector components
of the proposed experiment are described.Comment: Based on a talk given at Workshop on Positronium Physics, Zurich,
Switzerland, 30-31 May 200
Impfung gegen Pneumokokken überzeugt nicht restlos
Die Pneumokokkenimpfung gehört nicht zu den «beliebtesten» Impfungen. Bis vor kurzem empfahl das Bundesamt für Gesundheit, Risikopatienten jeden Alters und Menschen über 64 Jahre generell zu impfen. Dennoch liegt die Impfrate in Schweizer Hausarztpraxen bei knapp 2%. Eine Studie sucht Gründe
Can -- Conversion in Nuclei be a Good Probe for Lepton-Number Violating Higgs Couplings ?
Motivated by the improving sensitivity, , of experiments on and the enhanced Higgs nucleon interaction, we study this
lepton number violating process induced by Higgs exchange. Taking the possible
sensitivity, , we obtain the constraint on the
Higgs-muon-electron vertex, , to be less than
if the masses of the Higgs scalar and gauge boson are
the same. is also calculated for some models.Comment: 11 pages(revtex 3), TRI-PP-93-7
Chiral Prediction for the Scattering Length to Order
We evaluate the S-wave pion--nucleon scattering length in the framework
of heavy baryon chiral perturbation theory up--to--and--including terms of
order . We show that the order piece of the isovector
amplitude at threshold, , vanishes exactly. We predict for the
isovector scattering length, .Comment: 5 pp, LaTeX file, 2 figures (appended as separate compressed tar
file, amin.uu
A Xenon Condenser with a Remote Liquid Storage Vessel
We describe the design and operation of a system for xenon liquefaction in
which the condenser is separated from the liquid storage vessel. The condenser
is cooled by a pulse tube cryocooler, while the vessel is cooled only by the
liquid xenon itself. This arrangement facilitates liquid particle detector
research by allowing easy access to the upper and lower flanges of the vessel.
We find that an external xenon gas pump is useful for increasing the rate at
which cooling power is delivered to the vessel, and we present measurements of
the power and efficiency of the apparatus.Comment: 22 pages, 7 figures Corrected typos in authors lis
Extra dimensions and invisible decay of orthopositronium
We point out that some models with infinite additional dimension(s) of
Randall-Sundrum type predict the disappearance of orthopositronium (o-Ps) into
additional dimension(s). The experimental signature of this effect is the o-Ps
-> invisible decay of orthopositronium which may occur at a rate within three
orders of magnitude of the present experimental upper limit. This result
enhances existing motivations for a more sensitive search for this decay mode
and suggests additional directions for testing extra dimensions in non
accelerator experiments.Comment: 3 pages, to appear in Phys. Rev.
An Improved Limit on Invisible Decays of Positronium
The results of a new search for positronium decays into invisible final
states are reported. Convincing detection of this decay mode would be a strong
evid ence for new physics beyond the Standard Model (SM): for example the
existence of extra--dimensions, of milli-charged particles, of new light gauge
bosons or of mirror particles. Mirror matter could be a relevant dark matter
candidate.
In this paper the setup and the results of a new experiment are presented. In
a collected sample of about orthopositronium decay
s, no evidence for invisible decays in an energy window [0,80] keV was found
and an upper limit on the branching ratio of orthopositronium \invdecay could
be set: \binvdecay<4.2\times 10^{-7} (90% C.L.)
Our results provide a limit on the photon mirror-photon mixing strength
(90% C.L.) and rule out particles lighter
than the electron mass with a fraction of the
electron charge. Furthermore, upper limits on the branching ratios for the
decay of parapositronium (90%
C.L.) and the direct annihilation (90% C.L.) could be set.Comment: 17 pages, 7 figures, added references, fixed limit on millicharged
particles and changed two plots accordingl
GC-MS Based Metabolomics and NMR Spectroscopy Investigation of Food Intake Biomarkers for Milk and Cheese in Serum of Healthy Humans.
The identification and validation of food intake biomarkers (FIBs) in human biofluids is a key objective for the evaluation of dietary intake. We report here the analysis of the GC-MS and 1H-NMR metabolomes of serum samples from a randomized cross-over study in 11 healthy volunteers having consumed isocaloric amounts of milk, cheese, and a soy drink as non-dairy alternative. Serum was collected at baseline, postprandially up to 6 h, and 24 h after consumption. A multivariate analysis of the untargeted serum metabolomes, combined with a targeted analysis of candidate FIBs previously reported in urine samples from the same study, identified galactitol, galactonate, and galactono-1,5-lactone (milk), 3-phenyllactic acid (cheese), and pinitol (soy drink) as candidate FIBs for these products. Serum metabolites not previously identified in the urine samples, e.g., 3-hydroxyisobutyrate after cheese intake, were detected. Finally, an analysis of the postprandial behavior of candidate FIBs, in particular the dairy fatty acids pentadecanoic acid and heptadecanoic acid, revealed specific kinetic patterns of relevance to their detection in future validation studies. Taken together, promising candidate FIBs for dairy intake appear to be lactose and metabolites thereof, for lactose-containing products, and microbial metabolites derived from amino acids, for fermented dairy products such as cheese
ArDM: first results from underground commissioning
The Argon Dark Matter experiment is a ton-scale double phase argon Time
Projection Chamber designed for direct Dark Matter searches. It combines the
detection of scintillation light together with the ionisation charge in order
to discriminate the background (electron recoils) from the WIMP signals
(nuclear recoils). After a successful operation on surface at CERN, the
detector was recently installed in the underground Laboratorio Subterr\'aneo de
Canfranc, and the commissioning phase is ongoing. We describe the status of the
installation and present first results from data collected underground with the
detector filled with gas argon at room temperature.Comment: 6 pages, 3 figures, Light Detection In Noble Elements (LIDINE 2013
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