23 research outputs found
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Recent developments in high-speed, non-sampling electromagnetic calorimetry
Brief discussions are given of the work that has been done on the suppression of the slow component in BaF{sub 2}, the developments in the understanding of undoped CsI, and the properties of the new scintillator CeF{sub 3}. The properties of the Cherenkov radiator PbF{sub 2} along with test beam results are presented. Monte Carlo simulations indicate that, with the addition of a small amount of scintillator, PbF{sub 2}, can be made hadron compensating off-line so that the resolution of a compensating hadron calorimeter will not be degraded by its presence. 14 refs., 6 figs., 4 tabs
Search for the Rare Decay KL --> pi0 ee
The KTeV/E799 experiment at Fermilab has searched for the rare kaon decay
KL--> pi0ee. This mode is expected to have a significant CP violating
component. The measurement of its branching ratio could support the Standard
Model or could indicate the existence of new physics. This letter reports new
results from the 1999-2000 data set. One event is observed with an expected
background at 0.99 +/- 0.35 events. We set a limit on the branching ratio of
3.5 x 10^(-10) at the 90% confidence level. Combining the results with the
dataset taken in 1997 yields the final KTeV result: BR(KL --> pi0 ee) < 2.8 x
10^(-10) at 90% CL.Comment: 4 pages, three figure
Search for the decay K+ to pi+ gamma gamma in the pi+ momentum region P>213 MeV/c
We have searched for the K+ to pi+ gamma gamma decay in the kinematic region
with pi+ momentum close to the end point. No events were observed, and the 90%
confidence-level upper limit on the partial branching ratio was obtained, B(K+
to pi+ gamma gamma, P>213 MeV/c) < 8.3 x 10-9 under the assumption of chiral
perturbation theory including next-to-leading order ``unitarity'' corrections.
The same data were used to determine an upper limit on the K+ to pi+ gamma
branching ratio of 2.3 x 10-9 at the 90% confidence level.Comment: 15 pages, 3 figures; no change in the results, accepted for
publication in Physics Letters
Rare Decays
The rare decays of the meson have had a long tradition as a laboratory
for testing the symmetry properties of the weak interactions, and the manner in
which these symmetries are broken by higher order effects. Present--day
interest is focussed on decays that are suppressed by --symmetry or GIM
symmetry. Such decays, in the standard theory, are sensitive to effects of the
virtual top quark, and could also reveal new interactions transcending the
standard model. In addition, the radiative decays of the meson have become
a useful testing--ground for effective Lagrangians describing the low energy
interactions of pions, kaons and photons.Comment: Invited Talk at the Third Workshop on High Energy Particle Physics
(WHEPP 3) Madras, 1994, LaTex, 14 pages, 3 figures available upon reques
Lambda polarization from unpolarized quark fragmentation
The longstanding problem of explaining the observed polarization of Lambda
hyperons inclusively produced in the high energy collisions of unpolarized
hadrons is tackled by considering spin and k_T dependent quark fragmentation
functions. The data on Lambda's and Lambda-bar's produced in p-N processes are
used to determine simple phenomenological expressions for these new "polarizing
fragmentation functions", which describe the experiments remarkably well.Comment: LaTeX, 21+1 pages, 6 eps figures, uses epsfig.st
Measurements Of The Decay Kl → E+e-μ+μ-
Several 132 KL → e+e- μ+ μ- events were observed from the 1997 and 1999 runs of the KTeV experiments, with an estimated background of 0.8 events. In the first measurement of the parameter α using this decay mode, it was found that α=-1.59±0.37. No evidence was found for CP-violating contributions to the KLγ*γ* interaction.9014141801/1141801/5Wolfenstein, L., (1983) Phys. Rev. Lett., 51, p. 1945Belanger, G., Geng, C.Q., (1991) Phys. Rev. D, 43, p. 140Buras, A.J., Fleischer, R., (1998) Advanced Ser. Direct. High Energy Phys., 15, p. 65Uy, Z.E.S., (1991) Phys. Rev. D, 43, p. 802D'Ambrosio, G., Isidori, G., Portolès, J., (1998) Phys. Lett. B, 423, p. 385Alavi-Harati, A., (2001) Phys. Rev. Lett., 87, p. 71801. , KTeV CollaborationAlavi-Harati, A., (2001) Phys. Rev. Lett., 86, p. 5425. , KTeV CollaborationUy, Z.E.S., (2002) Eur. Phys. J. C, 23, p. 113Alavi-Harati, A., (2001) Phys. Rev. Lett., 87, p. 111802. , KTeV CollaborationHamm, J.C., (2002), Ph.D. thesis, The University of Arizona(Fermilab Report No. fERMILAB-THESIS-2002-09)Alavi-Harati, A., (1999) Phys. Rev. Lett., 83, p. 922. , KTeV CollaborationAlavi-Harati, A., (2000) Phys. Rev. D, 61, p. 072006. , KTeV CollaborationBrown, C., (1996) Nucl. Instrum. Methods Phys. Res., Sect. A, 369, p. 248Quinn, G.B., (2000), Ph.D. thesis, The University of ChicagoBarker, A.R., Huang, H., Toale, P.A., Engle, J., hep-ph/0210174Bergström, L., Massó, E., Singer, P., (1983) Phys. Lett., 131 B, p. 229Fanti, V., (1999) Phys. Lett. B, 458, p. 553. , NA48 Collaboratio
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The neutral kaon program at Fermilab and recent E731 results
Currently, Fermilab has a long-range program in neutral kaon physics which covers a wide variety of physics topics. In this report, I will be discussing the latest results from experiment E731 on the radiative decay of neutral kaons K{sub L,S} {yields} {pi}{sup +}{pi}{sup {minus}} {gamma}. These results include the first measurement of two new CP violation parameters: {eta}{sub +} {sub {minus}}{gamma} = (2.60{plus minus}0.54{plus minus}0.21) {center dot} 10{sup {minus}3}, and {phi}{sub +}{sub {minus}}{gamma} = (41{plus minus}28{plus minus}11){degrees}. The presence of a rho propogator form factor in the K{sub L} direct mission decay has been confirmed. Besides these results, the status of experiments E773 and E799, which are running in the 1991 fixed target run at Fermilab, and plans for future neutral kaon experiments will be discussed. 9 refs., 6 figs., 1 tab