2,453 research outputs found
A Preliminary Look at the Physics Reach of a Solar Neutrino TPC: Time-Independent Two Neutrino Oscillations
This paper will discuss the physics reach of a solar neutrino TPC containing
many tons of He4 under high pressure. Particular attention is given to the LMA
and SMA solutions, which are allowed by current data, and which are
characterized by a lack of time-dependent phenomena (either summer-winter or
day-night asymmetries). In this case, the physics of neutrino masses and mixing
is all contained in the energy dependence of the electron neutrino survival
probability, (or in its reciprocal, the electron neutrino disappearance
probability).Comment: 19 pages, 12 figure
Spectroscopy of B_c Mesons in the Relativized Quark Model
We calculate the spectrum of the charm-beauty mesons using the relativized
quark model. Using the wavefunctions from this model we compute the radiative
widths of excited c\bar{b} states. The hadronic transition rates between
c\bar{b} states are estimated using the Kuang-Yan approach and are combined
with the radiative widths to give estimates of the relative branching ratios.
These results are combined with production rates at the Tevatron and the LHC to
suggest promising signals for excited B_c states. Our results are compared with
other models to gauge the reliability of the predictions and point out
differences.Comment: 15 pages, 1 fig. uses revtex4. References adde
Exposure to pesticides and risk of amyotrophic lateral sclerosis: a population-based case-control study
A few epidemiologic studies have suggested an association of agricultural work and pesticidesexposure with a severe degenerative disease of the motor neurons, amyotrophic lateral sclerosis(ALS), though conflicting results have also been provided. We investigated through a populationbasedcase-control study the possible relation between overall occupational exposure to pesticidesand ALS risk in the northern Italy municipality of Reggio Emilia. By administering a questionnaire,we investigated occupational history and leisure-time habits of the 41 ALS patients diagnosed in the1995-2006 period, and of 82 age- and sex-matched randomly sampled population controls. Morecases than controls were found to have been exposed to pesticides for at least six months (31.7% vs13.4%, respectively), in all cases within the occupational environment. In a conditional logistic regressionmodel, we found an excess ALS risk associated with exposure to pesticides, with a relativerisk of 3.6 (95% confidence interval 1.2-10.5). Such association persisted after inclusion in the statisticalanalysis of potential confounders. Despite the limited statistical stability of the risk estimates,these results appear to indicate that occupational exposure to pesticides is a risk factor for ALS,suggesting the need to further investigate this issue
Analysis of short-term blood pressure variability in pheochromocytoma/paraganglioma patients
Data on short-term blood pressure variability (BPV), which is a well-established cardiovascular prognostic tool, in pheochromocytoma and paraganglioma (PPGL) patients is still lack and conflicting. We retrospectively evaluated 23 PPGL patients referred to our unit from 2010 to 2019 to analyze 24 h ambulatory blood pressure monitoring (24-h ABPM)-derived markers of short-term BPV, before and after surgical treatment. PPGL diagnosis was assessed according to guidelines and confirmed by histologic examination. The 24-h ABPM-derived markers of short-term BPV included: circadian pressure rhythm; standard deviation (SD) and weighted SD (wSD) of 24-h, daytime, and night-time systolic and diastolic blood pressure (BP); average real variability (ARV) of 24-h, daytime, and night-time systolic and diastolic BP. 7 males and 16 females of 53 ± 18 years old were evaluated. After surgical resection of PPGL we found a significant decrease in 24-h systolic BP ARV (8.8 ± 1.6 vs. 7.6 ± 1.3 mmHg, p < 0.001), in 24-h diastolic BP ARV (7.5 ± 1.6 vs. 6.9 ± 1.4 mmHg, p = 0.031), and in wSD of 24-h diastolic BP (9.7 ± 2.0 vs 8.8 ± 2.1 mmHg, p = 0.050) comparing to baseline measurements. Moreover, baseline 24-h urinary metanephrines significantly correlated with wSD of both 24-h systolic and diastolic BP. Our study highlights as PPGL patients, after proper treatment, show a significant decrease in some short-term BPV markers, which might represent a further cardiovascular risk factor
Neutrinos in a spherical box
In the present paper we study some neutrino properties as they may appear in
the low energy neutrinos emitted in triton decay with maximum neutrino energy
of 18.6 keV. The technical challenges to this end can be achieved by building a
very large TPC capable of detecting low energy recoils, down to a a few tenths
of a keV, within the required low background constraints. More specifically We
propose the development of a spherical gaseous TPC of about 10-m in radius and
a 200 Mcurie triton source in the center of curvature. One can list a number of
exciting studies, concerning fundamental physics issues, that could be made
using a large volume TPC and low energy antineutrinos: 1) The oscillation
length involving the small angle of the neutrino mixing matrix, directly
measured in this disappearance experiment, is fully contained inside the
detector. Measuring the counting rate of neutrino-electron elastic scattering
as a function of the distance of the source will give a precise and unambiguous
measurement of the oscillation parameters free of systematic errors. In fact
first estimates show that even with a year's data taking a sensitivity of a few
percent for the measurement of the above angle will be achieved. 2) The low
energy detection threshold offers a unique sensitivity for the neutrino
magnetic moment which is about two orders of magnitude beyond the current
experimental limit. 3) Scattering at such low neutrino energies has never been
studied and any departure from the expected behavior may be an indication of
new physics beyond the standard model. In this work we mainly focus on the
various theoretical issues involved including a precise determination of the
Weinberg angle at very low momentum transfer.Comment: 16 Pages, LaTex, 7 figures, talk given at NANP 2003, Dubna, Russia,
June 23, 200
Phenomenological Analysis of D Meson Lifetimes
The QCD-based operator-product-expansion technique is systematically applied
to the study of charmed meson lifetimes. We stress that it is crucial to take
into account the momentum of the spectator light quark of charmed mesons,
otherwise the destructive Pauli-interference effect in decays will lead
to a negative decay width for the . We have applied the QCD sum rule
approach to estimate the hadronic matrix elements of color-singlet and
color-octet 4-quark operators relevant to nonleptonic inclusive decays. The
lifetime of is found to be longer than that of because the latter
receives a constructive -exchange contribution, whereas the hadronic
annihilation and leptonic contributions to the former are compensated by the
Pauli interference. We obtain the lifetime ratio
, which is larger than some earlier theoretical
estimates, but still smaller than the recent measurements by CLEO and E791.Comment: 14 pages, 3 figure
Dark Matter Search Perspectives with GAMMA-400
GAMMA-400 is a future high-energy gamma-ray telescope, designed to measure
the fluxes of gamma-rays and cosmic-ray electrons + positrons, which can be
produced by annihilation or decay of dark matter particles, and to survey the
celestial sphere in order to study point and extended sources of gamma-rays,
measure energy spectra of Galactic and extragalactic diffuse gamma-ray
emission, gamma-ray bursts, and gamma-ray emission from the Sun. GAMMA-400
covers the energy range from 100 MeV to ~3000 GeV. Its angular resolution is
~0.01 deg(Eg > 100 GeV), and the energy resolution ~1% (Eg > 10 GeV). GAMMA-400
is planned to be launched on the Russian space platform Navigator in 2019. The
GAMMA-400 perspectives in the search for dark matter in various scenarios are
presented in this paperComment: 4 pages, 4 figures, submitted to the Proceedings of the International
Cosmic-Ray Conference 2013, Brazil, Rio de Janeir
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