arXiv subjects

Julia A. Thompson

Publications and source records attributed to Julia A. Thompson.

2 recordsLinked to original sources

arXiv2003

New, high statistics measurement of the K+ -> pi0 e+ neutrino (K+e3) branching ratio

E865 at the Brookhaven National Laboratory AGS collected about 70,000 K+e3 events with the purpose of measuring the K+e3 branching ratio relative to the observed K+ ->pi+pi0, K+ -> pi0 mu+ neutrino, and K+ -> pi+ pi0 pi0 decays. The pi0 in all the decays was detected using the e+e- pair from pi0 -> e+e- gamma decay and no photons were required. Using the Particle Data Group branching ratios for the normalization decays we obtain BR(Ke3gamma) = (5.13 +- 0.02stat +- 0.09sys +- 0.04norm)%, where K+e3gamma includes the effect of virtual and real photons (inclusive measurement). This result is ~ 2.3 sigma higher than the current Particle Data Group value. The implications of this result for the Vus element of the CKM matrix, and the matrix's unitarity are discussed.

hep-ex↗

arXiv1999

K+ -> pi+ mu+ mu- in E865 at BNL

Preliminary values for the K+ -> pi+ mu+ mu- branching ratio and form factor are reported, based on 400 events, a factor of 2 more in total events and 100 times the present world sample of fully reconstructed events. The results are consistent with previous results on the pi+ e+ e- mode. However, the relatively large slope of the form factor in q^2, lambda = 0.182+/-0.01+/-0.007, required to fit the pi+ e+ e- data and to give consistency between the pi+ e+ e- and pi+ mu+ mu- branching ratios, is larger than expected in simple models of the decays. The K+ -> pi+ mu+ mu- branching ratio we find, (9.23 +/- 0.6 stat +/- 0.58 syst)x10^-8, is the most precise measurement of this mode and is approximately 3.2 sigma larger than the previous measurement. These pi+ l+ l- results are inconsistent with O(p^4) Chiral Perturbation Theory but compatible with O(p^6). Systematic studies for both modes are still in progress.

hep-ex↗