An investigation of intermittency in proton-gold, oxygen-gold, sulphur-gold and sulphur-sulphur interactions at 200 GeV per nucleon

The intermittency phenomenon is investigated in proton-gold, oxygen-gold, sulphur-gold and sulphur-sulphur collisions at 200 GeV per nucleon. The data were taken with the NA 35 streamer chamber detector at the CERN SPS. The data samples are carefully corrected for double counting of tracks and for contamination from photon conversions, particle decays and secondary interactions. The analysis is carried out in terms of factorial moments, using a new definition, and of correlation integrals. Both methods show the presence of nonstatistical fluctuations (intermittency). The main conclusions are: The observation of the effect for pairs of hadrons with negative charges and its near absence for pairs of opposite charges is consistent with the assumption that Bose-Einstein correlations yield the dominant contribution. The intermittency effect is not proportional to (dn/dy)^–1 which would be expected in superposition models. The measured relation between the second and third factorial moment for negative hadrons indicates that genuine 3-particle correlations are small. The predictions of a Monte Carlo simulation which is based on the Lund Fritiof model with the inclusion of Bose-Einstein correlations agree with the experimental results.Deceased     

Off-shell NN annihilation studied in π+p interactions at 8 and 16 GeV/c

Interactions in which the baryon is emitted forwards in the c.m.s. are studied in 8 and 16 GeV/cπ⁺p collisions. These interactions are interpreted as representing baryon exchange. The properties of such off-shell $\text{N}$N annihilation events are studied. It is found that the multiplicity distribution of the multi-pion system as a function of the effective mass for events with |u_pp| < 1 GeV² is the same as for real $\text{N}\text{N}$ annihilations.     

Omega- and Omega+ production in central Pb + Pb collisions at 40 and 158A GeV

Results are presented on Omega production in central Pb+Pb collisions at 40 and 158A GeV beam energy. For the first time in heavy ion reactions, rapidity distributions and total yields were measured for the sum Omega(-) + Omega(+) at 40A GeV and for Omega(-) and Omega(+) separately at 158A GeV. The yields are strongly underpredicted by the string-hadronic UrQMD model but agree better with predictions from hadron gas models.     

Inclusive production of charged kaons in p+p collisions at 158 GeV/c beam momentum and a new evaluation of the energy dependence of kaon production up to collider energies

New data on the production of charged kaons in p+p interactions are presented. The data come from a sample of 4.8 million inelastic events obtained with the NA49 detector at the CERN SPS at 158 GeV/c beam momentum. The kaons are identified by energy loss in a large TPC tracking system. Inclusive invariant cross sections are obtained in intervals from 0 to 1.7 GeV/c in transverse momentum and from 0 to 0.5 in Feynman x. Using these data as a reference, a new evaluation of the energy dependence of kaon production, including neutral kaons, is conducted over a range from 3 GeV to $\mathrm{p}+\overline{\mathrm{p}}$ collider energies.     

Die Struktur der normalen rationalen Funktionen

Summary We determine the connected components of the set of normal elements of the family _m ⁿ [a,b] of rational functions. Numerical difficulties occuring with the computation of the Chebyshev approximation via the Remez algorithm can be caused by its disconnectedness. In order to illustrate this we give numerical examples.

Gefördert von der DFG unter Nr. Be 808/2     

New Applications of the CD Exciton Chirality Method. Stereochemical Assignment of Organic Compounds Containing Carboxylic Acid Groups

CD exciton chirality methods are described for the stereochemical assignment of organic compounds containing carboxylic acid groups. Using the chromophoric combination 2-naphthoate or 2-anthroate and 9-anthrylmethyl group the absolute stereochemistry of - and -hydroxy carboxylic acids can be deduced from a single CD measurement. Furthermore, as demonstrated with cyclic and acylic dicarboxylic acids, the direct esterification of sterically hindered carboxyl groups with 2-naphthol also allows the stereochemical assignment via CD spectroscopy.     

Asymmetry of π− meson emission in nucleus-nucleus collisions as a measure of the target-to-projectile ratio of the numbers of interacting nucleons

Experimental data on the forward-backward asymmetry of π^- emission in (d,⁴He,¹²C)¹⁸¹Ta interactions atp/A=4.2 GeV/c are presented. The absolute value of the asymmetry coefficient of the inclusive π^- production in the nucleon-nucleonCMS decreases asA _p ^?0.35 with increasing atomic mass of projectile nucleus. A method of obtaining the target-to-projectile ratio of the numbers of participant nucleonsN _t /N _p through measuring the velocity of the symmetric pion emission system is proposed. It has been found that N_t/N_p～A _p ^?0.73 .     

System-size dependence of strangeness production in nucleus-nucleus collisions at squareroot[sNN]=17.3 GeV

Emission of pi+/-, K+/-, phi, and Lambda was measured in near-central C+C and Si+Si collisions at 158 AGeV beam energy. Together with earlier data for p+p, S+S, and Pb+Pb, the system-size dependence of relative strangeness production in nucleus-nucleus collisions is obtained. Its fast rise and the saturation observed at about 60 participating nucleons can be understood as the onset of the formation of coherent systems of increasing size.