We have measured the differential cross sections for the production of
π
+, K
+, K
0, K
∗0
, φ, p, Λ and their corresponding antiparticles in separate samples of flavor-tagge
Z
0 → light-flavor (
u
u
...−
, d
d
−
,
or s
s
−
),
Z
0 → c
c
−
and
Z
0 → b
b
−
events. Clear flavor dependences are observed, and the results are compared with the predictions of three fragmentation models. We have also performed a direct measurement of
A
s
, the parity-violating coupling of the
Z
0 to strange quarks, by measuring the left-right-forward-backward production asymmetry in polar angle of the tagged
s quark. Our preliminary result is
A
s
= 0.82 ± 0.10(
stat.) ± 0.07(
syst.).
Nucl.Phys.Proc.Suppl.74:7-11,1999 We have measured the differential cross sections for the production of
$\pi^{+}$, $K^{+}$, $K^{0}$, $K^{*0}$, $\phi$, p, $\Lambda$ and their
corresponding ...antiparticles in separate samples of flavor-tagged $Z^{0}\to$
light-flavor ($u\bar{u}$, $d\bar{d}$, or $s\bar{s}$), $Z^{0}\to c\bar{c}$ and
$Z^{0}\to b\bar{b}$ events. Clear flavor dependences are observed, and the
results are compared with the predictions of three fragmentation models. We
have also performed a direct measurement of $A_{s}$, the parity-violating
coupling of the $Z^{0}$ to strange quarks, by measuring the
left-right-forward-backward production asymmetry in polar angle of the tagged
$s$ quark. Our preliminary result is $A_{s}$ = $0.82\pm 0.10(stat.)\pm
0.07(syst.)$.
Sudden unexpected deaths in epileptic persons are not rare events, most commonly encountered by the forensic pathologist rather than the clinician. Such deaths may represent 1-1.5% of all "natural" ...deaths certified by the medical examiner or coroner. The typical victim is a black male about 30 years of age who tends to abuse alcohol, with a history of generalized epilepsy for more than 1 year and likely for more than 10 years. There are a lack of obvious anatomic causes for the death at autopsy, but 60-70% of cases will have a lesion in the brain (most commonly old trauma) to explain the epilepsy. Most victims have no blood levels of anticonvulsant medications at the time of death. We have evolved a form for use by medical examiner/coroner's investigators at the scene to collect relevant information which will be of assistance to the pathologist in interpreting the case. Estimated prevalence of sudden epilepsy death, mechanisms, and other features of such cases are reviewed briefly.
We report results on two physics topics from the SLD experiment at the SLAC Linear Collider, using our full sample of 550,000 events of the type e+e- --> Z0 --> q-q(bar). The electron beam was ...polarized, enabling the quark and antiquark hemispheres to be tagged in each event. One physics topic is the first study of rapidities signed such that positive rapidity is along the quark rather than antiquark direction. Distributions of ordered differences in signed rapidity between pairs of particles are analyzed, providing the first direct observation of baryon number ordering along the q-q(bar) axis. The other topic is the first direct measurement of A_s, the parity-violating coupling of the Z0 to strange quarks, by measuring the left-right forward-backward production asymmetry in polar angle of the tagged s-quark. We obtain A_s = 0.895 +- 0.066(stat.) +- 0.062(syst.), which is consistent with the Standard Model and is currently the most precise measurement of this quantity.
The DIRC detector at BaBar Adam, I.; Aleksan, R.; Aston, D. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/1999, Letnik:
433, Številka:
1
Journal Article
Recenzirano
A dedicated particle identification system based on the Detection of Internally Reflected Cherenkov (DIRC) light will be used in the BaBar detector. We provide an overview of the DIRC concept, ...design, and expected performance of the production device and a status report on its construction and commissioning. The DIRC is expected to be operating in the BaBar detector on beam line at the PEP-II B Factory in late spring 1999.
We have measured the differential cross sections for the production of \(\pi^{+}\), \(K^{+}\), \(K^{0}\), \(K^{*0}\), \(\phi\), p, \(\Lambda\) and their corresponding antiparticles in separate ...samples of flavor-tagged \(Z^{0}\to\) light-flavor (\(u\bar{u}\), \(d\bar{d}\), or \(s\bar{s}\)), \(Z^{0}\to c\bar{c}\) and \(Z^{0}\to b\bar{b}\) events. Clear flavor dependences are observed, and the results are compared with the predictions of three fragmentation models. We have also performed a direct measurement of \(A_{s}\), the parity-violating coupling of the \(Z^{0}\) to strange quarks, by measuring the left-right-forward-backward production asymmetry in polar angle of the tagged \(s\) quark. Our preliminary result is \(A_{s}\) = \(0.82\pm 0.10(stat.)\pm 0.07(syst.)\).
We have measured gluon splitting into bottom quarks,
g→b
b
̄
, in hadronic
Z
0 decays collected by SLD between 1996 and 1998. The analysis was performed by looking for secondary bottom production in ...4-jet events of any primary flavor. 4-jet events were identified, and in each event a topological vertex-mass technique was applied to the two jets closest in angle in order to identify them as
b or
b
̄
jets. The upgraded CCD-based vertex detector gives very high
B-tagging efficiency, especially for
B hadrons with the low energies typical of this process. We measured the rate of
g→b
b
̄
production per hadronic event,
g
b
b
̄
, to be (2.44±0.59(stat.)±0.34(syst.))×10
−3.
Status of the DIRC detector at BaBar: early operational experience Adam, I; Aleksan, R; Aston, D ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2000, Letnik:
453, Številka:
1
Journal Article
Recenzirano
A novel type of Cherenkov ring imaging particle identification system (DIRC) based on the detection of ring images produced in long, fused silica radiator bars is being used to provide hadronic ...particle identification in the BaBar detector at PEP-II. The DIRC concept, design, fabrication, and initial performance will be briefly described. The DIRC is now fully commissioned, and has been operating in the BaBar detector on beam line at the PEP-II B Factory since late Spring 1999.
DIRC – A particle identification system for BaBar Höcker, Andreas
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2000, Letnik:
446, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The Detection of Internally Reflected Cherenkov light (DIRC) is a novel type of Cherenkov imaging device that has been developed, built and installed as part of the BaBar detector at the asymmetric ...B-factory PEP-II at SLAC. The DIRC is based on total internal reflection of Cherenkov photons produced and guided within thin, rectangular quartz bars covering the barrel region of BaBar. The photon detector is an array of photomultiplier tubes covering the photon phase space at the backward end of the bars. In its first few months of operation the DIRC performance has been found to achieve the design requirements. This note presents results from cosmic-ray data and an analysis of the first beam collision runs.
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