573 research outputs found
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Rare k-decays
This article reviews the current situation in the field of rare K decays: the relevant phenomenology, the present experimental situation, and prospects for the near future. Study of rare K decays can make a significant contribution in a number of different frontier areas of research in high-energy physics. In the area of CP violation, study of such rare decays as K(L)0 --> pi0e+e-, K(L)0 --> pi0mu+mu-, K(L)0 --> pi0nunuBAR, and muon polarization in K(L)0 --> mu+mu- can provide important complementary information to what has been learned from the decay K(L)0 --> pipi. Even though experiments with sufficient accuracy to make a meaningful study of CP violation are still a few years away, significant progress has been made in this general area during the last decade. A second major area of interest in the field of rare K decays is the search for processes forbidden in the Standard Model, e.g., K(L)0 --> mue and K+ --> pi+mu+e-. Various extensions of the Standard Model predict that these processes will occur with branching fractions in the range of 10(-10) to 10(-15). Experiments of the last decade have pushed the limits into the 10(-10) to 10(-11) range, and further improvements in sensitivity of one to two orders of magnitude can be expected in the next few years. K decays allow one also to study higher-order weak-interaction processes such as K(L)0 --> mu+mu-, K(L)0 --> e+e-, K+ --> pi+nunuBAR, which are forbidden to first order in the Standard Model. Because of strong suppression, these decay modes offer potential windows on new physics; in addition, they may offer the most reliable measurement of V(td), one of the elements of the weak mixing matrix in the quark sector. The studies of the mu+mu- channel have achieved data samples of close to 1000 events; the other two modes should be observed for the first time in the next few years. Finally, as a byproduct of these studies, one has been able to look simultaneously for new light particles into which the K meson could decay. Limits obtained for various hypothetical particles are summarized.Physic
Development of Detonation in Liquid Fuel Spray with Gaseous Oxidizer Preliminary Experiments
Detonation in liquid fuel spray with gaseous oxidize
Recoilless resonant neutrino capture and basics of neutrino oscillations
It is shown that the experiment on recoilless resonant emission and
absorption of , proposed recently by Raghavan, could have an
important impact on our understanding of the physics of neutrino oscillations.Comment: Additional information in the last chapte
Possible Effects of Quantum Mechanics Violation Induced by Certain Quantum Gravity on Neutrino Oscillations
In this work we tried extensively to apply the EHNS postulation about the
quantum mechanics violation effects induced by the quantum gravity of black
holes to neutrino oscillations. The possibilities for observing such effects in
the neutrino experiments (in progress and/or accessible in the near future)
were discussed. Of them, an interesting one was outlined specially.Comment: 18 pages, 0 figure, (1 REVTeX file
Neutrino mass matrix with U(2) flavor symmetry and neutrino oscillations
The three neutrino mass matrices in the model are studied
focusing on the neutrino oscillation experiments. The atmospheric neutrino
anomaly could be explained by the large oscillation.
The long baseline experiments are expected to detect signatures of the neutrino
oscillation even if the atmospheric neutrino anomaly is not due to the neutrino
oscillation. However, the model cannot solve the solar neutrino deficit while
it could be reconciled with the LSND data.Comment: 12 pages, LaTex file, to be published in PR
A straw drift chamber spectrometer for studies of rare kaon decays
We describe the design, construction, readout, tests, and performance of
planar drift chambers, based on 5 mm diameter copperized Mylar and Kapton
straws, used in an experimental search for rare kaon decays. The experiment
took place in the high-intensity neutral beam at the Alternating Gradient
Synchrotron of Brookhaven National Laboratory, using a neutral beam stop, two
analyzing dipoles, and redundant particle identification to remove backgrounds
Search for the Weak Decay of an H Dibaryon
We have searched for a neutral dibaryon decaying via and
. Our search has yielded two candidate events from which we set
an upper limit on the production cross section. Normalizing to the
inclusive production cross section, we find at 90% C.L., for an of mass
2.15 GeV/.Comment: 11 pages, 6 postscript figures, epsfig, aps, preprint, revte
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Association of a Workplace Sales Ban on Sugar-Sweetened Beverages With Employee Consumption of Sugar-Sweetened Beverages and Health.
ImportanceReductions in sugar-sweetened beverage (SSB) intake can improve health, but are difficult for individuals to achieve on their own.ObjectivesTo evaluate whether a workplace SSB sales ban was associated with SSB intake and cardiometabolic health among employees and whether a brief motivational intervention provides added benefits to the sales ban.Design, setting, and participantsThis before-after study and additional randomized trial conducted from July 28, 2015, to October 16, 2016, at a Northern California university and hospital assessed SSB intake, anthropometrics, and cardiometabolic biomarkers among 214 full-time English-speaking employees who were frequent SSB consumers (≥360 mL [≥12 fl oz] per day) before and 10 months after implementation of an SSB sales ban in a large workplace, with half the employees randomized to receive a brief motivational intervention targeting SSB reduction.InterventionsThe employer stopped selling SSBs in all workplace venues, and half the sample was randomized to receive a brief motivational intervention and the other half was a control group that did not receive the intervention. This intervention was modeled on standard brief motivational interventions for alcohol used in the workplace that promote health knowledge and goal setting.Main outcomes and measuresOutcomes included changes in SSB intake, Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), and measures of abdominal adiposity. The primary associations tested were the correlation between changes in SSB intake and changes in HOMA-IR.ResultsAmong the 214 study participants, 124 (57.9%) were women, with a mean (SD) age of 41.2 (11.0) years and a baseline mean (SD) body mass index of 29.4 (6.5). They reported a mean daily intake of 1050 mL (35 fl oz) of SSBs at baseline and 540 mL (18 fl oz) at follow-up-a 510-mL (17-fl oz) (48.6%) decrease (P < .001). Reductions in SSB intake correlated with improvements in HOMA-IR (r = 0.16; P = .03). Those not randomized to receive the brief intervention reduced their SSB intake by a mean (SD) of 246.0 (84.0) mL (8.2 [2.8] fl oz), while those also receiving the brief intervention reduced SSB intake by 762.0 (84.0) mL (25.4 [2.8] fl oz). From baseline to follow-up, there were significant reductions in mean (SE) waist circumference (2.1 [2.8] cm; P < .001).Conclusions and relevanceThis study's findings suggest that the workplace sales ban was associated with a reduction in SSB intake and a significant reduction in waist circumference among employees within 10 months. The randomized clinical trial portion of this study found that targeting those at high risk with a brief motivational intervention led to additional improvements. Workplace sales bans may offer a promising new private-sector strategy for reducing the health harms of SSB intake.Trial registrationClinicalTrials.gov identifier: NCT02585336
First Observation of the Rare Decay Mode K-long -> e+ e-
In an experiment designed to search for and study very rare two-body decay
modes of the K-long, we have observed four examples of the decay K-long -> e+
e-, where the expected background is 0.17+-0.10 events. This observation
translates into a branching fraction of 8.7^{+5.7}_{-4.1} X 10^{-12},
consistent with recent theoretical predictions. This result represents by far
the smallest branching fraction yet measured in particle physics.Comment: 9 pages, 3 figure
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