2024174
Bottom-quark forward-backward asymmetry in the standard model and beyond.
We computed the bottom-quark forward-backward asymmetry at the Tevatron in the standard model (SM) and for several new physics scenarios. Near the Z pole, the SM bottom asymmetry is dominated by tree level exchanges of electroweak gauge bosons. While above the Z pole, next-to-leading order QCD dominates the SM asymmetry as was the case with the top-quark forward-backward asymmetry. Light new physics, M(NP)≲150  GeV, can cause significant deviations from the SM prediction for the bottom asymmetry. The bottom asymmetry can be used to distinguish between competing new physics (NP) explanations of the top asymmetry based on how the NP interferes with s-channel gluon and Z exchange.
56563443
On Limit Cycles in Supersymmetric Theories
Abstract Contrary to popular belief conformality does not require zero beta functions. This follows from the work of Jack and Osborn, and examples in non-supersymmetric theories were recently found by some of us. In this Letter we show that such examples are absent in unitary N = 1 supersymmetric four-dimensional field theories. More specifically, we show to all orders in perturbation theory that the beta-function vector field of such theories does not admit limit cycles. A corollary of our result is that unitary N = 1 supersymmetric four-dimensional theories cannot be superscale-invariant without being superconformal.
121098391
FRACTION OF STOPPED ANTIPROTONS WHICH ANNIHILATE ON FREE HYDROGEN IN PROPANE.
121903889
The Design and Performance of a Halo Free Intense Extracted Proton Beam at Fermilab
Abstract A set of refocussing and collimation stages has been constructed in the Proton West beam line of the Proton Area at Fermi National Accelerator Laboratory which allows the operation of a halo-free intense proton beam. Measurements made at the first target point in the Proton West experimental hall demonstrate that this system is capable of targeting 10 12 pprotons in a 4 mm diameter spot with a halo density of about 150 particle/mm 2 at a distance of 5.6 cm from the focus. This system has been operated at 200, 300, and 400 GeV.
122661247
The super fixed target beauty facility at the SSC
Abstract The rationale for pursuing beauty physics at the SSC in a fixed target configuration is described. The increased beauty production cross section at the SSC, combined with high interaction rate capability of the proposed detector, results in 10 10–11 produced BB events per year. The long decay length of the B hadrons (≌10 cm) allows direct observation of B decays in the high resolution silicon microstrip vertex detector. To optimize the operation of the proposed beauty spectrometer and the SSC, parasitic extraction of attendant or artificially generated large amplitude protons using crystal channeling is proposed and explored. The large sample of fully reconstructed B events allows detailed studies various CP violating decays with requisite statistics to confront the standard model. The CP physics potentials of the proposed experiment is evaluated and compared with alternative approaches, such as asymmetric e + e − B Factories and specialized hadron colliders.
122051077
Results from experiments of crystal extraction of 900 GeV proton beams from the Tevatron Collider
The extraction of a small flux of primary protons from a collider in a parasitic manner is very attractive for a number of fixed target applications. The key requirements of the extracted beam are small average currents with relatively small temporal variations. At this time a bent crystal is installed in the Tevatron Collider which is designed to channel protons down an instrumented beam abort transfer line. In this paper the results of experiments with this crystal are presented. The impact on the high energy physics collider detectors of the crystal as a collimator and the transverse mechanism necessary to deposit the protons into the crystal for alignment purposes are described.
123918922
Properties and Performance of a Simple Electron - Hadron Calibration Beam in Proton West