Near threshold Cl(-)·CH3I photodetachment: apparent 2P1/2 channel suppression and enhanced 2P3/2 channel vibrational excitation

Cl(-)·CH(3)I cluster anion photoelectron images are recorded over a range of detachment wavelengths in the immediate post threshold region. The photoelectron spectral features fall into two categories. A number of weak, photon energy dependent transitions are observed and attributed to atomic anion fragmentation products. Several more intense, higher electron binding energy transitions result from single photon cluster anion detachment. Comparison with I(-)·CH(3)I suggests that the detachment process is more complicated for Cl(-)·CH(3)I. The single photon transition spacing is consistent with CH(3)I ν(3) mode excitation, but the two distinct vibronic bands of I(-)·CH(3)I detachment are not easily distinguished in the Cl(-)·CH(3)I spectra. Similarly, while the spectral intensities for both cluster anions show non-Franck Condon behavior, the level of vibrational excitation appears greater for Cl(-)·CH(3)I detachment. These observations are discussed in terms of low lying electronic states of CH(3)I along the C-I coordinate, and the influence of the CH(3)I moiety on the neutral halogen atom states.     

Q1(1290) and Q2 (1400) decay rates and their SU(3) implications

We summarize and combine the known information on the decay rates of the strangeness-one axial vector mesons, Q₁ and Q₂. From this information and the rate for B→ωπ, we determine the Q_A?Q_B mixing angle and the S-wave, symmetric and antisymmetric octet couplings for vector-pseudoscalar decays of axial vector mesons. If we assume the D(1285) and the E(1420) belong to the J^PC=1⁺⁺ nonet, we find the A₁ to have a mass of ～1.47 GeV and a large (>0.3 GeV) width.     

A study of the slope-mass correlation in the low mass K ππ system

The shape of the four-momentum transfer t′ distribution in the reactions K^±p→K^±π⁺π^?p at 13 GeV/c is studied for various partial waves as a function of the Kππ mass. Strong variation of the slope with effective mass is observed for the dominant J^P=1⁺ waves. For natural parity exchange it is found that, for Kππ masses up to 1.6 GeV, the slope of the t′ distribution is decreasing with increasing spin of the excited system, B₀?>B₁+>B₂⁺.     

Observation of a direct low-mass e+e− continuum in π-p interactions at 16 GeV/c

The production of prompt electron-positron pairs in 16 GeV/c π^-p collisions has been measured using the LASS spectrometer at SLAC. An excess of events is observed above the estimated contribution of direct and Dalitz decays of known resonances in the kinematic range defined by $\text{0.1?χ?0.45, 0?p}{}_{\mathrm{T}}\text{?0.8}\text{GeV}\text{c}$ and $\text{0.2?M(e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}\text{)?0.7}\text{GeV}\text{c}{}^2$. The excess signal decreases slowly with increasing M, but exhibits very steep χ and p_T² dependence.