A sample of 3120 K super(+/-)--> pi super(+/-) mu super(+) mu super(-) decay candidates with (3.3+/-0.7)% background contamination has been collected by the NA48/2 experiment at the CERN SPS, ...allowing a detailed study of the decay properties. The branching ratio was measured to be BR=(9.62+/-0.25)x10 super(-8). The form factor W(z), where z=(M sub( mu mu )/M sub(K)) super(2), was parameterized according to several models. In particular, the slope of the linear form factor W(z)=W sub(0)(1+ delta z) was measured to be delta =3.11+/-0.57. Upper limits of 2.9x10 super(-2) and 2.3x10 super(-2) on possible charge asymmetry and forward-backward asymmetry were established at 90% CL. An upper limit BR(K super(+/-)--> pi mu super(+/-) mu super(+/-))<1.1x10 super(-9) was established at 90% CL for the rate of the lepton number violating decay.
A sample of more than one million K±→π+π−e±ν (Ke4) decay candidates with less than one percent background contamination has been collected by the NA48/2 experiment at the CERN SPS in 2003–2004, ...allowing a detailed study of the decay properties. The branching ratio, inclusive of Ke4γ decays, is measured to be BR(Ke4)=(4.257±0.016exp±0.031ext)×10−5 with a total relative error of 0.8%. This measurement complements the study of S- and P-wave hadronic form factors by assigning absolute values to the relative hadronic form factors obtained earlier in a simultaneous analysis of the ππ scattering lengths conducted on the same data sample. The overall form factor normalization fs=5.705±0.017exp±0.031ext is obtained with a total relative precision of 0.6%.
The distribution of the K±→π±π+π− decays in the Dalitz plot has been measured by the NA48/2 experiment at the CERN SPS with a sample of 4.71×108 fully reconstructed events. With the standard Particle ...Data Group parameterization the following values of the slope parameters were obtained: g=(−21.134±0.017)%, h=(1.848±0.040)%, k=(−0.463±0.014)%. The quality and statistical accuracy of the data have allowed an improvement in precision by more than an order of magnitude, and are such as to warrant a more elaborate theoretical treatment, including pion–pion rescattering, which is in preparation.
An overview of the APEmille project Bartoloni, A.; Cabasino, S.; Cosimi, M. ...
Nuclear physics. Section B, Proceedings supplement,
1998, 1998-1-00, Volume:
60, Issue:
1
Journal Article
Peer reviewed
This paper describes the main architectural features of the APEmille parallel architecture. It covers in some details the hardware and software details of this machine, now in an advanced development ...phase. It finally presents a status report of the project.
APEmille is a SPMD parallel processor under development at INFN, Italy, in cooperation with DESY, Germany. APEmille is suited for grand challenges computational problems such as QCD simulations, ...climate modelling, neural networks, computational chemistry, numerical wind tunnels, seismic and combustion simulations. Its 1 Teraflop/s peak performance and its architecture, together with its language features, allow such applications to execute effectively.
APEmille is based on an array of custom arithmetic processors arranged on a tridimensional torus. The processor is optimized for complex computations and has a peak performance of 528 Mflop at 66 MHz. Each processing element has 8 Mbytes of locally addressable RAM.
On the software side particular emphasis is devoted to the programming languages that will be available (TAO and C++) and their object oriented, dynamic characteristics: with TAO it is possible to develop language extensions similar to the usual HEP notation; with C++ the portability from and towards different platforms is made possible.
An overview of the APEmille parallel computer Aglietti, F; Bartoloni, A; Battista, C ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/1997, Volume:
389, Issue:
1
Journal Article
Peer reviewed
We describe the architecture of the APEmille Parallel Computer, the new generation of the APE family of processors optimized for Lattice Gauge Theory simulations. We emphasize the features of the new ...machine potentially useful for applications in other areas of computational physics.
As first observed by the NA48/2 experiment at the CERN SPS, the π0π0 invariant mass (M00) distribution from K±→π±π0π0 decay shows a cusp-like anomaly at M00=2m+, where m+ is the charged pion mass. An ...analysis to extract the ππ scattering lengths in the isospin I=0 and I=2 states, a0 and a2, respectively, has been recently reported. In the present work the Dalitz plot of this decay is fitted to a new empirical parameterization suitable for practical purposes, such as Monte Carlo simulations of K±→π±π0π0 decays.
PDF
