Measurement of the longitudinal and transverse cross-section in e+e− annihilation at s=35–44 GeV

On the infrared sensitivity of the longitudinal cross section in ee annihilation

We have calculated the contributions proportional to β 0 α n+1 s to the longitudinal fragmentation function in ee annihilation to all orders of perturbation theory. We use this result to estimate higher-order perturbative corrections and nonperturbative corrections to the longitudinal cross section σL and discuss the prospects of determining αs from σL. The structure of infrared renormalons in ...

Measurement of the total cross section for hadronic production by e(+)e(-) annihilation at energies between 2.6-5 GeV

Using the upgraded Beijing Spectrometer, we have measured the total cross section for e(+)e(-) annihilation into hadronic final states at center-of-mass energies of 2.6, 3.2, 3.4, 3.55, 4.6, and 5.0 GeV. Values of R, sigma(e(+)e(-)-->hadrons)/sigma(e(+)e(-)-->&mgr;(+)&mgr;(-)), are determined.

The Ratio of the Direct Photon Production Cross Section at 630 GeV and at 1800 GeV

We measure the ratio of the isolated direct photon prodution cross section at √ s = 630 GeV to that at √ s = 1800 GeV for the central (|η| < 0.9) and forward (1.6 < |η| < 2.5) rapidity regions. We compare the result with next to leading order QCD predictions using CTEQ parton distribution functions.

Measurement of the Open Charm Cross-section in 200 Gev Heavy-ion Collisions at Star

Theory predicts that charm quarks are produced by initial gluon fusion during the very early stages of the matter produced in a relativistic heavyion collision. These gluon fusion reactions occur through high momentum transfer (Q) processes before the thermalization of the collision fireball [1]. Gluon fusion reactions scale with the number of binary (nucleon-nucleon) collisions, allowing us to...

Measurement of the total cross section for e+e-âƒTMhadrons at â‹ıs=10.52 GeV