A search for the exotic meson X(5568) decaying into the B_{s}^{0}π^{±} final state is performed using data corresponding to 9.6 fb^{-1} from pp[over ¯] collisions at sqrt[s]=1960 GeV recorded by the Collider Detector at Fermilab. No evidence for this state is found and an upper limit of 6.7% at the 95% confidence level is set on the fraction of B_{s}^{0} produced through the X(5568)→B_{s}^{0}π^{±} process.
We present neutrino-based options for verifying that the nuclear reactors at North Korea's Yongbyon Nuclear Research Center are no longer operating or that they are operating in an agreed manner, precluding weapons production. Neutrino detectors may be a mutually agreeable complement to traditional verification protocols because they do not require access inside reactor buildings, could be installed collaboratively, and provide persistent and specific observations. At Yongbyon, neutrino detectors could passively verify reactor shutdowns or monitor power levels and plutonium contents, all from outside the reactor buildings. The monitoring options presented here build on recent successes in basic particle physics. Following a dedicated design study, these tools could be deployed in as little as one year at a reasonable cost. In North Korea, cooperative deployment of neutrino detectors could help redirect a limited number of scientists and engineers from military applications to peaceful technical work in an international community. Opportunities for scientific collaboration with South Korea are especially strong. We encourage policymakers to consider collaborative neutrino projects within a broader program of action toward stability and security on the Korean Peninsula.
Context: Shutdown or repurposing of reactors at YongbyonNorth Korea has built and operated nuclear reactors since the 1960s. As far as public evidence indicates, all functioning reactors have been at the Yongbyon Nuclear Research Center. Plutonium for North Korea's nuclear weapons program has come from a 5 MW e (20 MW th ) 1 graphite-moderated, gas-cooled, natural uranium-fueled reactor first operated in 1986. 2 Also at Yongbyon is a 100 MW th experimental light water reactor (ELWR), fueled with low-enriched uranium (LEU) 3 and apparently approaching operation. 4 Yongbyon hosts another small research reactor operated intermittently since the 1960s, remnants of a 50 MW e reactor project decommissioned in the 1990s, facilities for nuclear fuel fabrication and reprocessing, and a uranium enrichment plant. 5
We measure the particle-level forward-backward production asymmetry in bb pairs with masses (m bb ) larger than 150 GeV=c 2 , using events with hadronic jets and employing jet charge to distinguish b fromb. The measurement uses 9.5 fb −1 of pp collisions at a center-of-mass energy of 1.96 TeV recorded by the CDF II detector. The asymmetry as a function of m bb is consistent with zero, as well as with the predictions of the standard model. The measurement disfavors a simple model including an axigluon with a mass of 200 GeV=c 2 , whereas a model containing a heavier 345 GeV=c 2 axigluon is not excluded.
Detecting the Diffuse Supernova Neutrino Background at Super-Kamiokande requires designing state-of-the-art background removal technique to reject radioactivity induced by cosmic muon spallation, and identify atmospheric neutrino interactions. Identifying the neutron produced by the interaction of DSNB antineutrinos would allow to remove most of these backgrounds, but is particularly challenging in pure water. With the advent of the SK-Gd era, with Gadolinium being dissolved in the SK water, the efficiency of the neutron tagging procedure will increase dramatically, and the SK experiment will make significant gains in its sensitivity to the DSNB. I will present the role of neutron tagging and the challenges it provides, as well as discuss the impact of the SK-Gd project.
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