We have measured parity-nonconserving optical rotation in the vicinity of the M1 absorption transition at 876 nm in bismuth. The result, R = Im(E1PNC/M1) = (-10.0 ± 1.0) centerdot 10-8, is in agreement with calculations based on the standard model of the electroweak interaction. The predicted form of the PNC rotation spectrum has been verified to high accuracy.
No description provided.
Parity non-conserving (PNC) optical rotation has been measured by laser polarimetry in the 648 nm magnetic dipole transition (6p$^{3}J$=$\frac{3}{2}\rightarrow$6p$^{3}J'=\frac{5}{2}$) in atomic bismuth. The experiment involves finding the small differences in rotation between selected frequency points in the vicinity of the F = 6 $\rightarrow$ F' = 7 hyperfine component. Faraday rotation, which can be distinguished from PNC rotation by its wavelength dependence, is used in locking the laser frequency and calibrating the PNC' effect. Results obtained over a six-year period are summarised; a detailed discussion of error sources and associated tests is given. The final result for the PNC parameter of the 648 nm transition is R = (-9.3 $\pm$ 1.4)X10$^{-8}$. This is in agreement with the measurements of Birich et a/ but not with those of Barkov and Zolotorev. It is also consistent with the standard model of the electroweak interaction, but the uncertainty in the atomic theory is now the limiting factor in the comparison.
Axis error includes +- 0.0/0.0 contribution (?////).
Axis error includes +- 0.0/0.0 contribution (?////).
We report a new measurement of parity nonconserving (PNC) optical rotation on the 6p1/2- 6p3/2 transition in atomic thallium near 1283 nm. The result expressed in terms of the quantity R=Im{E1PNC/M1} is −(15.68±0.45)×10−8, and is consistent with current calculations based on the standard model. In addition, limits have been set on the much smaller nuclear spin-dependent rotation amplitude at RS=(0.04±0.20)×10−8; this is consistent with theoretical estimates which include a nuclear anapole contribution.
Spin of the Tl nucleus is 1/2.
Parity-violating optical rotation induced by the neutral weak-current interaction has been detected and measured for the first time in atomic thallium vapour. Accurate atomic calculations predicting the size of the rotation are available for this element; thallium also benefits from the Z3 enhancement of the effect. The magnetic-dipole transition 6p1/2-6p3/2 at 1.283 μm was excited using a single-mode semiconductor laser and the small optical rotation was measured using a sensitive polarimeter. The result, expressed in terms of the quantity R = Im E1p.v./M1, is - 12.5(19)10-8 and is consistent with recent calculations based on the standard model.
Spin of the Tl nucleus is 1/2.
Two-photon interactions have been studied with the SLAC-LBL Mark II magnetic detector at SPEAR. The cross section for η′ production by the reaction e+e−→e+e−η′ has been measured at beam energies from 2.0 to 3.7 GeV. The radiative width Γγγ(η′) has been determined to be 5.8±1.1 keV (±20% systematic uncertainty). Upper limits on the radiative widths of the f(1270), A2(1310), and f′(1515) tensor mesons have been determined. A search has been made for production of the E(1420) by γγ collisions, but no signal is observed.
No description provided.
NO SIGNAL ABOVE BACKGROUND SEEN. UPPER LIMITS AT 95 PCT CL GIVEN.
We present a measurement of the cross section for the reaction e + e − → e + e − π + π − π + π − at SPEAR. This channel is found to be large and dominated by the process γγ → ϱ 0 ϱ 0 → π + π − π + π − . The cross section, which is small just above the four-pion threshold, exhibits a large enhancement near the ϱ 0 ϱ 0 threshold.
Axis error includes +- 0.0/0.0 contribution (THE QUOTED ERRORS INCLUDE VARIOUS SYSTEMATIC ERRORS ADDED QUADRATICALLY).
We report the results of a laser experiment to search for the parity-nonconserving optical rotation in atomic bismuth. We work at wavelengths close to the 648-nm J=32 — J=52 M1 transition from the ground state. We find R=Im(E1M1)=(+2.7±4.7)×10−8, in disagreement with the theoretical value R=−30×10−8 predicted for this transition on the basis of the Weinberg-Salam model of the weak interactions combined with relativistic central-field atomic theory.
No description provided.