Triple Electroweak Gauge-Boson Production at Fermilab Tevatron Energies

We calculate the three gauge-boson production in the Standard Model at Fermilab Tevatron energies. At $\sqrt s=2$ TeV in $p\bar p$ collisions, the cross sections for the triple gauge-boson production are typically of order 10 femtobarns (fb). For the pure leptonic final states from the gauge-boson decays and with some minimal cuts on final state photons, the cross sections for $p \bar p \rightarrow W^\pm \gamma\gamma, Z\gamma\gamma$ and $W^+W^- \gamma$ processes are of order a few fb, resulting in a few dozen clean leptonic events for an integrated luminosity of 10 fb$^{-1}$. The pure leptonic modes from other gauge-boson channels give significantly smaller rate. Especially, the trilepton modes from $W^+W^-W^\pm$ and $t \bar t W^\pm \rightarrow W^+W^-W^\pm$ yield a cross section of order 0.1 fb if there is no significant Higgs boson contribution. For a Higgs boson with $m_H^{} \simeq 2M_Z^{}$, the triple massive-gauge-boson production rate could be enhanced by a factor of $4-6$.Comment: RevTeX 3.0; 14 pages plus 7 figures; ps files available via anonymous ftp at ftp://ucdhep.ucdavis.edu/han/vvv/vvv.ps,fig*_vvv.p

An ultra-wide bandwidth (704 to 4 032 MHz) receiver for the Parkes radio telescope

We describe an ultra-wide-bandwidth, low-frequency receiver recently installed on the Parkes radio telescope. The receiver system provides continuous frequency coverage from 704 to 4032 MHz. For much of the band ( ${∼}60$ ), the system temperature is approximately 22 K and the receiver system remains in a linear regime even in the presence of strong mobile phone transmissions. We discuss the scientific and technical aspects of the new receiver, including its astronomical objectives, as well as the feed, receiver, digitiser, and signal processor design. We describe the pipeline routines that form the archive-ready data products and how those data files can be accessed from the archives. The system performance is quantified, including the system noise and linearity, beam shape, antenna efficiency, polarisation calibration, and timing stability