D.H. Miller

Analyzing power in inclusive π+ and π− production at high xF with a 200 GeV polarized proton beam☆

The analyzing power in inclusive charged pion production has been measured using the 200 GeV Fermilab polarized proton beam. A striking dependence in x(F) is observed in which A(N) increases from 0 to 0.42 with increasing x(F) for the pi+ data and decreases from 0 to -0.38 with increasing x(F) for pi- data. The kinematic range covered is 0.2 less-than-or-equal-to x(F) less-than-or-equal-to 0.9 and 0.2 less-than-or-equal-to p(T) 2.0 GeV/c. In a simple model our data indicate that at large x(F) the transverse spin of the proton is correlated with that of its quark constituents.

Large-xF spin asymmetry inπ0 production by 200-GeV polarized protons

The spin asymmetryAN for inclusive π0 production by 200-GeV transversely-polarized protons on a liquid hydrogen target has been measured at Fermilab over a wide range ofxF, with 0.5<pT<2 GeV/c. AtxF>0.3, the asymmetry rises with increasingxF and reaches a value ofAN=0.15±0.03 in the region 0.6<xF<0.8. This result provides new input regarding the question of the internal spin structure of transversely-polarized protons.

High-xT single-spin asymmetry in π0 and η production at xF=0 by 200 GeV polarized antiprotons and protons☆☆☆

A measurement of the single-spin asymmetry A(N) in P up + P --> pi-0 + X at 200 GeV with x(F) = O shows a transition in the production process from a low-x(T) regime with A(N) = 0, through an intermediate region of negative asymmetry, to a high-x(T) regime with A(N) > 0.3. This transition occurs at x(T) almost-equal-to 0.4 and is consistent with x(T)-scaling of A(N) in pion production using polarized beams or targets from square-root -s = 5.2 to 19.4 GeV. Results for A(N) in eta-production by polarized protons and in pi-0 production by polarized antiprotons are also presented.

Inclusive

We have measured inclusive ..gamma.. and ..pi../sup 0/ production in multiprong events produced by e/sup +/e/sup -/ annihilation in the center-of-mass energy range 4.9 to 7.4 GeV. We find that ..pi../sup 0/ inclusive cross section to be consistent in shape and normalization with half the charged-..pi.. cross section between chi = 0.15 and 0.60, with an integrated inclusive cross-section ratio of sigma (..pi../sup 0/)/ vertical-bar (sigma (..pi../sup +/) + sigma (..pi../sup -/) vertical-bar = 0.47 +- 0.10.

\gamma

We present experimental results on measuring a single spin asymmetry in η-meson production in the interaction of transversely polarized protons and antiprotons at plab = 200 GeV/c with a proton target in the region 0.2 < xF < 0.7 for p↑p, 0.3 < xF < 0.7 for p↑p and 0.7 < pT < 2.0 GeV/c. A comparison of single spin asymmetries in π- and η-meson production is made.

and

Abstract We report the results of a search for fractionally charged particles in e + e − reactions at a center of mass energy of 29 GeV. We find no evidence for such particles and present upper limitts on R q = σ q q X/σ μμ for change 1 3 e and 2 3 e which range from 1 to 8 × 10 −2 for mass up to 12 GeV/ c 2 .

\pi^0

We have measured inclusive ..gamma.. and ..pi../sup 0/ production in multiprong events produced by e/sup +/e/sup -/ annihilation in the center-of-mass energy range 4.9 to 7.4 GeV. We find that ..pi../sup 0/ inclusive cross section to be consistent in shape and normalization with half the charged-..pi.. cross section between chi = 0.15 and 0.60, with an integrated inclusive cross-section ratio of sigma (..pi../sup 0/)/ vertical-bar (sigma (..pi../sup +/) + sigma (..pi../sup -/) vertical-bar = 0.47 +- 0.10.

Production in

Abstract We present measurements of the cross section for inclusive D and K meson production in e+e− annihilation in the center of mass energy range 3.6 to 5.8 GeV. D production accounts for most of the increase in the total cross section for hadron production in e+e− annihilation at energies above 4 GeV.

e^+ e^-

Proportional chambers are used in the PEP Free Quark Search to identify and remove possible background sources such as particles traversing the edges of counters, to permit geometric corrections to the dE/dx and TOF information from the scintillator and Cerenkov counters, and to look for possible high cross section quarks. The present beam pipe has a thickness of 0.007 interaction lengths (λi) and is followed in both arms (each with 45° ≤ θ ≤ 135°. Δ = 90°) by 5 proportional chambers, each 0.0008 λi thick with 32 channels of pulse height readout, and by 3 thin scintillator planes, each 0.003 λi thick. Following this thin front end, each arm of the detector has 8 layers of scintillator (one with scintillating light pipes) interspersed with 4 proportional chambers and a layer of lucite Cerenkov counters. Both the calculated ion statistics and measurements using He-CH4 gas in a test chamber indicate that the chamber efficiencies should be > 98% for q = 1/3. The Landau spread measured in the test was equal to that observed for normal q = 1 traversals. One scintillator plane and thin chamber in each arm will have an extra set of ADCs with a wide gate bracketing the normal one so timing errors and tails of earlier pulses should not produce fake quarks.

Annihilation

The π0 inclusive and semi‐inclusive, single‐spin asymmetries have been measured using transversely‐polarized, 200‐GeV/c proton and antiproton beams colliding with an unpolarized hydrogen target. The measured asymmetries are consistent with a value of zero within the error bars for the kinematic regions, −0.15<xF<+0.15 and 1<pT<4.5 GeV/c. These data indicate that the higher‐twist contribution in QCD to the single‐spin asymmetry in inclusive π0 production may not be as large as was previously expected. Additional evidence for such a conclusion comes from the measurement of a semi‐inclusive π0‐charged particle asymmetry, where the associated charged particles are detected opposite to the π0 azimuthal direction. This experiment also has a high‐statistics measurement of the inclusive π0 cross sections for pp and pp collisions at 200 GeV/c.