S. Cihangir

Three Pion Production on Nuclei at 200 GeV

We have carried out a systematic study of the coherent dissociation of pions into 3 pions using nuclear targets. The experiment was performed at Fermilab using a high resolution forward spectrometer. Data were taken with carbon, copper and lead targets at an incident momentum of 202.5 GeV/c. Results are presented on momentum transfers, 3-pion masses, and on the nuclearA-dependence of the production cross section.

Experimental constraints on JPC=1-+, I=1, Hybrid mesons

AbstractUsing data on coherent production of π+π+π- systems in π+ collisions with nuclei we exclude the existence ofJPC=1−+,I=1, exotic hybrid mesons with masses below 1.5 GeV and widths greater than 20 MeV, provided that their primary coupling is to πρ systems. Hybrid states with just such properties have recently been predicted from arguments based on QCD sum rules. Our experimental limit is based on Primakoff production of these states, and on an argument using vector dominance to relate their radiative widths to πρ channels. There has been increasing interest of late in the existence of hybrid states, which, in the case of mesons, contain a valence gluon in addition to aqn

Operational performance of a large liquid argon photon calorimeter

bar q

Radiative decays of low lying mesons

n pair in a color-octet state [1–5]. The pursuit of spectroscopic gluon degrees of freedom has been strongly motivated by the general QCD picture of hadrons, as well as by many specific calculations based on QCD sum rules, lattice simulations, and more phenomenological approaches such as QCD-bag models. Although much effort, both thoretical and experimental, has been devoted to the spectroscopy of glueballs, for which several candidates exist [6], it has also been realized that hybrid states may be as amenable to discovery, and perhaps less ambiguous to interpretation.

Radiative widths of K and ρ mesons

Abstract We report a measurement of the radiative decay of the K∗− (890). The width for the transition K∗− → K− γ is 62 ± 14 keV. The resulting ratio of decay probabilities (K∗0 → K0γ)/(K∗− → K−γ), while consistent with predictions of certain quark models, does not agree with expectations from unbroken SU(3) symmetry.

New results of radiative meson decays

Abstract We describe the performance of a large (0.9 × 1.4 m 2 ) liquid argon photon calorimeter in high energy experiments at Fermilab. Resolutions for π 0 and electron showers, obtained under data-taking conditions, are compared with electron-beam calibration results. Exceptional spatial and time resolutions have been achieved for isolated showers ( σ x , y σ t ∼6 ns). Electron data up to energies of 80 GeV and π 0 data up to 180 GeV are presented.

Radiative width of the rho/sup -/ meson

Abstract Using beryllium as a selective hadron filter, the kaon fraction of a positively charged 200 GeV/ c secondary beam has been increased from 3% to ∼15% without an appreciable effect on tagging efficiency.

Inclusive production of direct photons in 200-GeV/c collisions

We have investigated the Coulomb dissociation of charged pions and kaons on heavy nuclei. New values for the electromagnetic transition rates Γ(ρ±u2009→u2009π±γ) and Γ(K*±u2009→u2009K±γ) have been extracted from the data using the Primakoff formalism. The first measurements for Γ(A2+u2009→u2009π+γ), Γ(K**+(1430)u2009→u2009K+γ), Γ(B+(1235)u2009→u2009π+γ), and Γ(A1+u2009→u2009π+γ) will also be presented.