397 research outputs found
Measurements of time dependent CP asymmetry in decays with BELLE
A study of CP violation in decays by time
dependent angular analysis is discussed. Status of time independent analyses
for other decays is also reported. The data used for the analyses are
taken with the Belle detector at KEK.Comment: 4 pages, 3 figures, Proceeding of the talk in parallel session
(CP-3-5) at ICHEP2002, Amsterdam, Netherland, 24-31 July (2002
The time-of-propagation counter for Belle II
The Belle II detector operating at the future upgrade to the KEKB accelerator
will perform high-statistics precision investigations into the flavor sector of
the Standard Model. As charged hadron identification is a vital element of the
experiment's success, the time-of-propagation (TOP) counter has been chosen as
the primary particle identification device in the barrel region of Belle II.
The TOP counter is a compact variant of the detection of internally reflected
Cherenkov light (DIRC) technique and relies heavily on exquisite single photon
timing resolution with micro-channel plate photomultiplier tubes. We discuss
the general principles of TOP operation and optimization of the Belle II TOP
configuration, which is expected to provide 4 sigma or better separation of
kaons and pions up to momenta of approximately 4 GeV/c.Comment: 5 pages, 5 figures, 2 tables; Submitted to special edition of NIMA,
Proceedings of RICH201
Multi-pion production in the d d -> alpha X reaction
A simple model, based on two parallel and independent N N -> d pi processes,
has recently been proposed for two-pion production in the d d -> alpha X
reaction. It reproduces all observed features, including the sharp peak
structure in momentum distributions (the ABC effect) and the strong
oscillations in the deuteron vector and tensor analyzing powers. This model is
now extended to describe also four-pion production with the same basic
mechanism, but with two n p -> d pi pi processes as input. The calculations of
the high missing mass spectra are within about 30% of the experimental data for
beam energies in the range 1.9 < T_d < 2.4 GeV.Comment: 7 pages, LaTeX2e, 2 PS figures, submitted to Phys. Lett.
Recent charm mixing results from BABAR, Belle, and CDF
A summary of the results of several recent studies of charm mixing is
presented. A number of different methods were used, including the measurement
of lifetime ratios for final states of different CP, time dependence of
wrong-sign hadronic decays, fits to time-dependent Dalitz plots, and searches
for wrong-sign semi-leptonic decays. Taken together, they suggest mixing is of
order 1%. The status of searches for indirect CP violation is also reported.Comment: 7 pages, 2 figures, proceedings from PHIPSI0
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Study of electron and neutrino interactions
This is the final report for the DOE-sponsored experimental particle physics program at Virginia Tech to study the properties of the Standard Model of strong and electroweak interactions. This contract (DE-AS05-80ER10713) covers the period from August 1, 1980 to January 31, 1993. Task B of this contract, headed by Professor Alexander Abashian, is described in this final report. This program has been pursued on many fronts by the researchers-in a search for axions at SLAC, in electron-positron collisions in the AMY experiment at the TRISTAN collider in Japan, in measurements of muon decay properties in the MEGA and RHO experiments at the LAMPF accelerator, in a detailed analysis of scattering effects in the purported observation of a 17 keV neutrino at Oxford, in a search for a disoriented chiral condensate with the MiniMax experiment at Fermilab, and in an R&D program on resistive plate counters that could find use in low-cost high-quality charged particle detection at low rates
Search for Lepton Flavor-Violating "tau -> mu gamma" decay
We search for the lepton flavor-violating "tau -> mu gamma" decay using 29.7
million tau pairs accumulated by the Belle experiment. The main background
sources are found to be tau pairs with "tau -> mu nu nu" decay and radiative
dimuon events. One event is observed in the signal region, while 2.5 +- 0.6
background events are expected. A preliminary upper limit Br(tau -> mu gamma) <
6 x 10^{-7} at the 90% confidence limit is obtained.Comment: Invited talk at the Seventh International Workshop on Tau Lepton
Physics (TAU02), Santa Cruz, Ca, USA, Sept 2002, 6 pages, LaTeX, 13 eps
figure
Production of isoscalar pion pairs in the pd -> 3He pi pi reaction near threshold
The production near threshold of isoscalar pion pairs in the pd -> 3He(pi
pi)^0 reaction is estimated in a two-step model which successfully describes
the production of eta, omega and eta' mesons. A virtual pion beam, generated
through an NN -> d pi reaction on one of the nucleons in the deuteron, produces
a second pion via a pi N -> pi pi N reaction on the other nucleon. Using the
same scale factor as for heavy meson production, the model reproduces the total
pi^0 pi^0 production rate determined at an excess energy of 37 MeV. There are
some indications in the data for a suppression of events with low pi pi masses,
as in the pi^- p -> pi^0 pi^0 n reaction, and this is confirmed within the
model. The model suggests that a significant fraction of the charged pion
production in the p d -> 3He pi^+ pi^- reaction at Q=70 MeV might be associated
with isoscalar pion pairs, though this does not explain the strong dependence
observed on the pi^+ pi^- relative momentum angle.Comment: 13 pages including 4 eps figure
The role of the Roper resonance in n p --> d (pi pi)
In this work, a model for the n p --> d (pi pi) reaction is developed. It is
shown that the structure of the deuteron momentum spectra for a neutron beam
momentum of 1.46 GeV can be explained as a consequence of the interplay of two
mechanisms involving the excitation of the N^*(1440) resonance and its
subsequent decay into N (pi pi)^{T=0}_{S-wave} and Delta pi respectively. The
relevance of the present analysis for the study of the Roper excitation and
decay properties, as well as for the interpretation of other two-pion
production experiments is discussed.Comment: 13 pages, 6 ps figure
Measurement and analysis of extracellular cardiac potentials to guide radiofrequency ablation therapy for fibrillation
Metrics for completeness of cardiac antiarrhythmic ablation lesions are needed to guide ablation therapy. Extracellular bipolar cardiac potentials were measured on either side of the lesion in isolated rabbit hearts (N=25). Three analyses of the signals were examined as possible metrics. Variances in dominant frequency of fibrillatory recordings decreased after ablation by factors of 1.51 for the frequency-domain analysis using the Fast-Fourier Transform; and 1.45 for the time-domain analysis using intervals between super-threshold peaks. This suggests an increase in organization of fibrillation. Morphologies of the signals from different sides of the lesion examined with cross-correlation indicated no consistent change in morphology before vs. after ablation. Slow pacing to determine translesion stimulus-excitation delays (TED) showed that mean TED increased post-ablation, consistent with increased conduction path length. During fibrillation, no consistent change in TED was observed. Thus, certain metrics may be useful to distinguish lesion completeness
The ABC Effect in Double-Pionic Nuclear Fusion and a pn Resonance as its Possible Origin
The ABC effect -- a long-standing puzzle in double-pionic fusion -- has been
reexamined by the first exclusive and kinematically complete measurements of
solid statistics for the fusion reactions , He and He using the WASA detector, first at
CELSIUS and recently at COSY -- the latter with a statistics increased by
another two orders of magnitude. In all cases we observe a huge low-mass
enhancement in the -invariant mass accompanied by a pronounced
excitation. For the most basic fusion reaction, the reaction, we observe in addition a very pronounced resonance-like
energy dependence in the total cross section with a maximum 90 MeV below the
mass and a width of only 50 MeV, which is five times smaller
than expected from a conventional -channel excitation. This
reveals the ABC effect to be the consequence of a s-channel resonance with the
formfactor of this dibaryonic state being reflected in the low-mass enhancement
of the -invariant mass. From the fusion reactions to He and He
we learn that this resonance is robust enough to survive even in nuclei.Comment: conference proceedings PANIC 0
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