An Unconventional Transition Radiation Detector

Abstract

A transition radiation detector operating at low gas pressures was built at Yerevan and tested at FERMILAB. At low pressure, total d~ is decreased without loss of efficiency for transidx tion radiation x-rays.Data with rr's and p's at 40, 100 and 200 GeV/c momenta are presented.• The data shows that 0.5% overlap between rr's and p's may be achieved at 40 GeV/c with a 2 m long detector.

Can theX(3872)be a1++four-quark state?

“…4, the validity of the vacuum saturation for these condensates. The relatively small contribution of the dimension-eight condensates may justify the validity of our approximation, unlike in the case of the 5-quark current correlator, as noticed in [42]. However, the partial compensation of these two terms indicate the sensitivity of the central value of the mass prediction on the way the OPE is truncated.…”

QCD sum rules study of mesons

“…4, the validity of the vacuum saturation for these condensates. The relatively small contribution of the dimension-eight condensates may justify the validity of our approximation, unlike in the case of the 5-quark current correlator, as noticed in [30]. We get an upper limit constraint for M 2 by imposing the rigorous constraint that the QCD continuum contribution should be smaller than the pole contribution.…”