Physics Opportunities with the 12 GeV Upgrade at Jefferson Lab

This white paper summarizes the scientific opportunities for utilization of the upgraded 12 GeV Continuous Electron Beam Accelerator Facility (CEBAF) and associated experimental equipment at Jefferson Lab. It is based on the 52 proposals recommended for approval by the Jefferson Lab Program Advisory Committee.The upgraded facility will enable a new experimental program with substantial discovery potential to address important topics in nuclear, hadronic, and electroweak physics.Comment: 64 page

Measurement of the Probability of Gluon Splitting into Charmed Quarks in Hadronic Z Decays

We have measured the probability, n(g->cc~), of a gluon splitting into a charm-quark pair using 1.7 million hadronic Z decays collected by the L3 detector. Two independent methods have been applied to events with a three-jet topology. One method relies on tagging charmed hadrons by identifying a lepton in the lowest energy jet. The other method uses a neural network based on global event shape parameters. Combining both methods, we measure n(g->cc~)= [2.45 +/- 0.29 +/- 0.53]%

Search for the Xb and other hidden-beauty states in the π+π−ϒ(1S) channel at ATLAS

This Letter presents a search for a hidden-beauty counterpart of the X(3872) in the mass ranges of 10.05–10.31 GeV and 10.40–11.00 GeV, in the channel Xb→π+π−ϒ(1S)(→μ+μ−), using 16.2 fb−1 of pp   collision data collected by the ATLAS detector at the LHC. No evidence for new narrow states is found, and upper limits are set on the product of the Xb cross section and branching fraction, relative to those of the ϒ(2S), at the 95% confidence level using the CLS approach. These limits range from 0.8% to 4.0%, depending on mass. For masses above 10.1 GeV, the expected upper limits from this analysis are the most restrictive to date. Searches for production of the ϒ(13DJ), , and states also reveal no significant signals

Identifying the G protein, G z α

The signalling pathway associated with pertussis and cholera toxin sensitive G proteins have been extensively investigated. In contrast, the function and associated signal transduction cascade for the pertussis toxin insensitive G protein, G(Zα), have remained elusive. Therefore, the aim of this study was to identify the signal transduction pathway associated with G(Zα) by using the protein identification techniques of matrix assisted laser desorption ionization-time of flight mass spectroscopy and N-terminal Edman sequencing. We have chosen this technique to identify proteins that G(Zα) associates with and to gain insights into the potential role this G protein plays in cells. As G(Zα) is predominantly localized in neuronal tissues, homogenates of whole brain tissue were used. G(Zα) and its associated proteins were immunoprecipitated from brain tissue and identified. The immunoprecipitation of four proteins (140, 46, 41 and 36 kDa) was shown to be inhibited in the presence of the G (Zα) peptide. These proteins were subsequently identified as phospholipase C (PLC)-γ, β or γ-actin, G(Zα) and G(β), the β subunit of heterotrimeric G proteins, respectively. These results suggest that G(Zα) exists in a protein complex with the actin cytoskeleton and an important intracellular signalling enzyme, PLC-γ. These methods are powerful techniques for determining protein-protein interactions, and provide the first step to the identification of signalling proteins that G(Zα) associates with. However further experimentation will be required to determine the biological relevance of these protein interactions.</p