Dilepton production by neutrinos in the Fermilab 15-foot bubble chamber

Abstract

In an exposure of the Fermilab 15-foot neon-hydrogen bubble chamber to a quadrupole triplet neutrino beam, 49 p -e i and 14 p + e events with e * momenta greater than 0.3 GeV/c have been observed, yielding p e rates per charged-current event of (0.73+0.11)% and (1.1 *0.3)%, respectively. The p -e + rate shows no strong energy dependence in the range from 30 to 300 GeV. The 18 neutral strange particles observed in the 63 events contain 14 K:, 2 A, and 2A/K,O ambiguities, suggesting that the events are predominantly D-meson production and decay and that the A: + h e x branching ratio is very small. The corrected numbers of neutral strange particles per p e and p ' e event are 1.2=t0.3 and 0.6?:!, respectively. Properties of the events, including strange-particle production, are compared t o p $p * events in the same experiment and to a charm production and decay model, and good agreement is found, apart from a possible enhancement at -5-6 GeV/c2 in the mass of the system recoiling against the p in p ' e ( a n d p i p ) events. As reported previously, four events show short-lived-particle decays, and D-meson lifetime estimates are reevaluated using the final event sample. One p ' e and three p e events were observed. The p eevents are consistent with background and lead to a p e / p e i ratio of less than 0.07 (90% confidence level) for e' momenta above 0.8 GeV/c. Five candidates for dilepton production by electron neutrinos and antineutrinos in the beam are consistent with approximately 1% rates. No good three-lepton candidates were found, and one, previously reported, four-lepton candidate was found.

Dilepton and trilepton production by antineutrinos and neutrinos in neon

“…The production rates differ widely and the experimental situation is unclear, mostly because of large uncertainties in subtracting the background in counter experiments, and because of the poor statistics in bubble chamber experiments. However our results and others [3,26] and recent reanalyses of old data [20,26] suggest the earlier rates may be too high.…”

“…3a, b). The accumulation of events in this mass region -where the experimental resolution in W is about 0.8 GeV -has previously led to speculations on quasi-elastic beauty baryon production [3,10]. One would expect larger values of the transverse momentum of the e-or #-out of the (V, lepton) plane for events with B decay: e-and #-from events with 5 < W <7 GeV are labelled in Figs. 7a, b*.…”

Measurement of the γ*γ*→η′ transition form factor

“…where (x → 1 − x) stands for the first term with replacement of x by 1 − x, α s ðμ 2 Þ is the QCD coupling strength, and Significant effort has been invested to determine the DAs of pseudoscalar mesons at intermediate values of momentum transfer [15][16][17][18][19]. In contrast to the case of one off-shell photon, the TFF for two off-shell photons is almost insensitive to the shape of the DA, because the amplitude Eq.…”

“…In the case of the η 0 meson, Λ P is found to be 849 AE 6 MeV=c 2 from the approximation of F η 0 ðQ 2 ; 0Þ with one off-shell photon [14]. The value of F η 0 ð0; 0Þ can be obtained from the measured value of the η 0 two-photon width Γ η 0 →2γ ¼ 4.30 AE 0.16 keV [20] using the formula [16] Fð0…”

Physics of charmed hadrons

“…[57]. CLEO II [91] E687 [92] CLEO II [94] E653 [95] E687 [96] E791 [97] X`2Y2 % Р90%-ÐÑÏ ÖÓÑÄÐÇ AEÑÔÕÑÄÇÓÐÑÔÕË [102]. £ ÒÑÔÎÇAEÐÇÇ ÄÓÇÏâ, ÑAEÐÂÍÑ, ÖAEÂÎÑÔß ÔÖÜÇÔÕÄÇÐÐÑ ÖÎÖÚÛËÕß ÕÑÚÐÑÔÕß ËÊÏÇÓÇÐËÌ, ËÔÒÑÎßÊÖâ ÏÇÕÑAE, ÒÓËÏÇ-ÐÇÐÐÞÌ ÄÒÇÓÄÞÇ ÍÑÎÎÂÃÑÓÂÙËÇÌ HRS [84] (ÔÏ.…”