26 research outputs found
Heavy Quark Lifetimes, Mixing and CP Violation
This paper emphasizes four topics that represent some of the year's
highlights in heavy quark physics. First of all, a review is given of charm
lifetime measurements and how they lead to better understanding of the
mechanisms of charm decay. Secondly, the CLEO collaboration's new search for
charm mixing is reported, which significantly extends the search for new
physics in that sector. Thirdly, important updates in Bs mixing are summarized,
which result in a new limit on the mass difference, and which further constrain
the unitarity triangle. Finally, the first efforts to measure CP violation in
the B system are discussed. Results are shown for the CDF and ALEPH
measurements of sin(2beta), as well as the CLEO branching fraction measurements
of B-->Kpi,pipi, which have implications for future measurements of alpha.Comment: 25 pages, 15 figures. Talk given at the XIX International Symposium
on Lepton and Photon Interactions, Stanford University, August 9-14, 199
Interpreting experimental bounds on D^0 - \bar{D^0} mixing in the presence of CP violation
We analyse the most recent experimental data regarding D^0 - \bar{D^0}
mixing, allowing for CP violation. We focus on the dispersive part of the
mixing amplitude, M^D_{12}, which is sensitive to new physics contributions. We
obtain a constraint on the mixing amplitude: |M^D_{12}| < 6.2\times 10^{-11}
MeV at 95% C.L. . This constraint is weaker by a factor of about three than the
one which is obtained when no CP violation is assumed.Comment: 9 pages, revtex4; One reference updated, one reference added,
footnote 3 correcte
The EPR paradox, Bell's inequality, and the question of locality
Most physicists agree that the Einstein-Podolsky-Rosen-Bell paradox
exemplifies much of the strange behavior of quantum mechanics, but argument
persists about what assumptions underlie the paradox. To clarify what the
debate is about, we employ a simple and well-known thought experiment involving
two correlated photons to help us focus on the logical assumptions needed to
construct the EPR and Bell arguments. The view presented in this paper is that
the minimal assumptions behind Bell's inequality are locality and
counterfactual definiteness, but not scientific realism, determinism, or hidden
variables, as is often suggested. We further examine the resulting constraints
on physical theory with an illustration from the many-worlds interpretation of
quantum mechanics -- an interpretation that we argue is deterministic, local,
and realist, but that nonetheless violates the Bell inequality.Comment: 28 pages; change of title, minor wording changes, move to TeX forma
Convalescent plasma in patients admitted to hospital with COVID-19 (RECOVERY): a randomised controlled, open-label, platform trial
SummaryBackground Azithromycin has been proposed as a treatment for COVID-19 on the basis of its immunomodulatoryactions. We aimed to evaluate the safety and efficacy of azithromycin in patients admitted to hospital with COVID-19.Methods In this randomised, controlled, open-label, adaptive platform trial (Randomised Evaluation of COVID-19Therapy [RECOVERY]), several possible treatments were compared with usual care in patients admitted to hospitalwith COVID-19 in the UK. The trial is underway at 176 hospitals in the UK. Eligible and consenting patients wererandomly allocated to either usual standard of care alone or usual standard of care plus azithromycin 500 mg once perday by mouth or intravenously for 10 days or until discharge (or allocation to one of the other RECOVERY treatmentgroups). Patients were assigned via web-based simple (unstratified) randomisation with allocation concealment andwere twice as likely to be randomly assigned to usual care than to any of the active treatment groups. Participants andlocal study staff were not masked to the allocated treatment, but all others involved in the trial were masked to theoutcome data during the trial. The primary outcome was 28-day all-cause mortality, assessed in the intention-to-treatpopulation. The trial is registered with ISRCTN, 50189673, and ClinicalTrials.gov, NCT04381936.Findings Between April 7 and Nov 27, 2020, of 16 442 patients enrolled in the RECOVERY trial, 9433 (57%) wereeligible and 7763 were included in the assessment of azithromycin. The mean age of these study participants was65·3 years (SD 15·7) and approximately a third were women (2944 [38%] of 7763). 2582 patients were randomlyallocated to receive azithromycin and 5181 patients were randomly allocated to usual care alone. Overall,561 (22%) patients allocated to azithromycin and 1162 (22%) patients allocated to usual care died within 28 days(rate ratio 0·97, 95% CI 0·87–1·07; p=0·50). No significant difference was seen in duration of hospital stay (median10 days [IQR 5 to >28] vs 11 days [5 to >28]) or the proportion of patients discharged from hospital alive within 28 days(rate ratio 1·04, 95% CI 0·98–1·10; p=0·19). Among those not on invasive mechanical ventilation at baseline, nosignificant difference was seen in the proportion meeting the composite endpoint of invasive mechanical ventilationor death (risk ratio 0·95, 95% CI 0·87–1·03; p=0·24).Interpretation In patients admitted to hospital with COVID-19, azithromycin did not improve survival or otherprespecified clinical outcomes. Azithromycin use in patients admitted to hospital with COVID-19 should be restrictedto patients in whom there is a clear antimicrobial indication
Sciphile.org — an Online Science Library for Teachers
Prof. Blaylock will demonstrate a website (http://sciphile.org) he has developed to help teachers and parents teach science. The site hosts a growing library of short science activities and lessons, which strive to complement traditional lectures with engaging in-class materials. For college teachers, the site offers a number of opportunities. At the most basic level, it can be source of inspiration for their own courses and a place to publish and share teaching materials they develop. Instructors can also use Sciphile.org as a laboratory for college students to contribute to a shared body of science education resources. Students can create materials, share them privately with instructors, and later submit them for general publication if they like. By publishing their work, students have the opportunity to receive public feedback and commentary and produce work with a legacy beyond the confines of the university course. Sciphile.org also allows several authors to collaborate on the same work, providing opportunities for group projects
Sciphile.org — an Online Science Library for Teachers
Prof. Blaylock will demonstrate a website (http://sciphile.org) he has developed to help teachers and parents teach science. The site hosts a growing library of short science activities and lessons, which strive to complement traditional lectures with engaging in-class materials. For college teachers, the site offers a number of opportunities. At the most basic level, it can be source of inspiration for their own courses and a place to publish and share teaching materials they develop. Instructors can also use Sciphile.org as a laboratory for college students to contribute to a shared body of science education resources. Students can create materials, share them privately with instructors, and later submit them for general publication if they like. By publishing their work, students have the opportunity to receive public feedback and commentary and produce work with a legacy beyond the confines of the university course. Sciphile.org also allows several authors to collaborate on the same work, providing opportunities for group projects
Direct measurement of the decays of charmed D mesons
Charmed D mesons produced in the decay of the t/1(3770) are observed by the
Mark III detector at SPEAR. A new technique is applied to these data to derive
D branching fractions which do not rely on the measurement of D production
cross sections. Measurements are presented for three decay modes of the D0
( K-1pi+, K-1pi-1pi+ 1pi+ and K-1pi+ 1pi0 ) and four decay modes of the n+ ( K-1pi+ 1pi+,
K-1pi+1pi+1pi0 , K-1pi+ and K-1pi+1pi0 ). The resulting branching fractions are significantly
larger than previous measurements.U of I OnlyThesi