121338670
Cluster production and the pomeron in meson-baryon and baryon-baryon collisions
Abstract The bare pomeron in models based on duality diagrams is found to contribute very differently at low energies to pp and Kp total cross-sections. A simple quantitative comparison of these cross-sections is found to be consistent with phenomenological cluster production models.
120889645
A topological approach to high-energy large transverse momentum interactions
We discuss the high pT strong interaction from a topological (1/Nf) expansion viewpoint. Topology of quark line graphs is used to classify the underlying process rather than constituent scattering, all constituents being implicitly confined. The distinction between “jets” and “background” is clarified in a very simple dynamical model. Although the model does not require quarks as dynamical entities, many of its features are in agreement with parton model predictions.
122501083
The pomeron and the f-trajectory in the topological expansion
Abstract The topological expansion for planar and cylinder terms is re-examined using a multi-Regge approximation for the planar, many-particle amplitude. The phase structure of the reggeon-reggeon-particle vertex is shown to lead to distinct pomeron and f-trajectories in the imaginary part of the elastic two-body amplitude.
118600385
Toward a sub-ppm measurement of the Fermi constant
The Fermi constant, G_F, describes the strength of the weak force and is determined most precisely from the mean life of the positive muon, tau_mu. Advances in theory have reduced the theoretical uncertainty on G_F as calculated from tau_mu to a few tenths of a part per million (ppm). The remaining uncertainty on G_F is entirely experimental, and is dominated by the uncertainty on tau_mu. The MuLan experiment is designed to measure the muon lifetime to part-per-million precision, a better-than twenty-fold improvement over the previous generation of experiments. In 2007, we reported an intermediate result, tau_mu=2.197013(24) microseconds (11 ppm), which is in excellent agreement with the previous world average. This mean life was measured using a pulsed surface muon beam stopped in a ferromagnetic target, surrounded by a symmetric scintillator detector array. Since this intermediate measurement, the detector was instrumented with waveform digitizers, the muon beam rate and beam extinction were increased, and two data sets were acquired on different targets, each containing over 10^12 muon decays. These data will lead to a new determination of G_F to better than a part per million.
119279381
A tungsten/scintillating fiber electromagnetic calorimeter prototype for a high-rate muon (g -2) experiment
Abstract A compact and fast electromagnetic calorimeter prototype was designed, built, and tested in preparation for a next-generation, high-rate muon ( g − 2 ) experiment. It uses a simple assembly procedure: alternating layers of 0.5-mm-thick tungsten plates and 0.5-mm-diameter plastic scintillating fiber ribbons. This geometry leads to a detector having a calculated radiation length of 0.69 cm, a Moliere radius of 1.73 cm, and a measured intrinsic sampling resolution term of ( 11.8 ± 1.1 ) % / E ( GeV ) , in the range 1.5–3.5 GeV. The construction procedure, test beam results, and GEANT-4 comparative simulations are described.
18829100
Data acquisition system for the MuLan muon lifetime experiment
Abstract We describe the data acquisition system for the MuLan muon lifetime experiment at Paul Scherrer Institute. The system was designed to record muon decays at rates up to 1 MHz and acquire data at rates up to 60 MB/s. The system employed a parallel network of dual-processor machines and repeating acquisition cycles of deadtime–free time segments in order to reach the design goals. The system incorporated a versatile scheme for control and diagnostics and a custom web interface for monitoring experimental conditions.