The production of the excited charmed baryon doublet Lc * via fragmentation is studied. An analysis of the subsequent hadronic decays of the doublet within the framework of heavy hadron chiral perturbation theory produces expressions for both the angular distribution of the decay products and the polarization of the final state heavy baryon in terms of various nonperturbative fragmentation para...

Recent results on open charm production at HERA are presented. Charm quarks are identified via the reconstruction of D-mesons. The charm contribution to the proton structure function is shown. Evidence for an exotic anti-charmed baryon state observed by H1 is presented. The data show a narrow resonance in the Dp invariant mass combination at 3099±3stat±5syst MeV. The resonance is interpreted as...

Experiments with ultra-relativistic nuclei are performed to produce and study the quarkgluon plasma. This new state of matter is predicted to exist at high temperatures and/or high baryon densities. Numerical solutions of QCD using lattice techniques imply that the critical temperature (at zero baryon density) is about 170 MeV [1]. Comprehensive surveys of the various experimental approaches on...

To extract information about polarized gluons in the proton, production of charmed hadrons, in particular, Λc baryon in pp collisions was studied. We calculated the transverse momentum distribution and the pseudo-rapidity distribution of the spin correlation asymmetry ALL between the initial proton and the produced Λc . Those statistical sensitivities were also calculated under the condition of...

During the last few years many newD, Ds, charmonium, and charmed baryon excited states have been discovered. Some of these states were not expected theoretically; their masses, widths, quantum numbers, and decay modes did not fit the existing spectroscopic classification, which was based mostly on potential model calculations. The theoretical models had to be improved and new approaches have be...

We present an analysis of particle production yields measured in central Au-Au collisions at RHIC in the framework of the statistical thermal model. We demonstrate that the model extrapolated from previous analyses at SPS and AGS energy is in good agreement with the available experimental data at √ s = 130 GeV implying a high degree of chemical equilibration. Performing a χ fit to the data, the...

The narrow width of the exotic narrow baryon resonance Θ might be explained by mixing between the two nearly degenerate states that arise in models with two diquarks and an antiquark. The only open Θ decay channel is KN . When two states both coupled to a single dominant decay mode are mixed by the loop diagram via this decay mode, diagonalization of the loop diagram decouples one mass eigensta...

The strange-anticharmed Pentaquark is a uud¯ cs or udd¯ cs five-quark baryon that is expected to be either a narrow resonance, or possibly even stable against strong decay. We describe this hyperon here; its structure, binding energy and lifetime, resonance width, production mechanisms and decay modes. We estimate production cross sections, techniques to reduce backgrounds in search experiments...

Abstract The photoproduction processes of the exotic Θ+(1540) baryon and the K ∗ meson from the nucleon targets, i.e., γn → K∗−Θ+ and γp → K̄∗0Θ+, are investigated in a hadronic model. We consider K and K∗ exchanges as well as the s and u channel nucleon and Θ terms. Various spin asymmetries together with cross sections are first computed in order to study the production mechanisms and the parit...

The weak production of L’s in nucleon-nucleon scattering is studied in a meson-exchange framework. The weak transition operator for the NN→NL reaction is identical to a previously developed weak strangenesschanging transition potential LN→NN that describes the nonmesonic decay of hypernuclei. The initial NN and final Y N state interaction has been included by using realistic baryon-baryon force...