M. P. Comets

Further Evidence Concerning Narrow Isovector Nonstrange Dibaryons

The missing-mass spectra for the 3He(p, d)X reaction (Bx = 2, Tx = 1) have been measured at Tp = 1.2 GeV for θd = 33°. Narrow structures have been observed at Mx = 2.122, 2.198 and possibly 2.233 GeV with FWHM, respectively, equal to 5.2, 8.1 and 13 MeV. These results, obtained under new kinematical conditions, confirm previous data.

Experimental search for B=2, T=2 bound states around the πNN threshold

Abstract The differential cross section and analyzing power have been measured for the p( p , π − )X reaction at an incident energy of 1450 MeV and a pion angle of 13.8° in order to study eventual dibaryonic T =2 structures in the vicinity of the πNN threshold. No statistically significant evidence for such structures corresponding to πNN bound states or six-quark states could be established. Upper limits to the cross section are deduced. Analyzing power data are discussed.

{pi}N and {eta}p deexcitation channels of the N* and {delta} baryonic resonances between 1470 and 1680 MeV

Two reactions, pp{yields}ppX and pp{yields}p{pi}{sup +}X, are used to study the 1.47{<=}M{<=}1.680 GeV baryonic mass range. Three different final states are considered in the invariant masses: N* or {delta}{sup +},n{pi}{sup +} or p{pi}{sup 0}, and p{eta}. The last two channels are defined by software cuts applied to the missing mass of the first reaction. Several narrow structures are extracted with widths {sigma}({gamma}) varying between 3 and 9 MeV. Some structures are observed in one channel but not in another. Such nonobservation may be due either to the spectrometer momenta limits or to the physics (e.g., no such disintegration channel is allowed from the narrow state considered).We tentatively conclude that the broad Particle Data Group (PDG) baryonic resonances--N(1520)D{sub 13},N(1535)S{sub 11},{delta}(1600)P{sub 33},N(1650)S{sub 11}, and N(1675)D{sub 15}--are collective states built from several narrow and weakly excited resonances, each having a (much) smaller width than the one reported by PDG.

Possible evidence for a narrow isovectorB=2 resonance below pion production threshold

Some evidence is presented for a narrow peak at 1969±2 MeV (FWHM=9±2 MeV) in the missing mass spectrum of the3He(p, d) reaction, with 3 standard deviations. The nature of this state, the mass of which is below the NN threshold, is discussed in connection with structures found in other experiments.

p⃗p⇒Δ++Δ0, p⃗p⇒Δ++n and p⃗p⇒pπ+X reactions at energies between 1.5 and 2.1 GeV

The reaction p-vectorp{yields}p{pi}{sup +}X has been studied at three energies (T{sub p}=1520, 1805 and 2100 MeV), using the Saturne polarized proton beam and the SPES3 experimental facility. The analyzing powers of p-vectorp{yields}{delta}{sup ++}{delta}{sup 0}, p-vectorp{yields}{delta}{sup ++}n and p-vectorp{yields}p{pi}{sup +}X reactions have been studied between 0 deg. and 17 deg. in the lab., which corresponds to an angular range between 0 deg. and 100 deg. (c.m.)The reaction pp→pπ+X has been studied at three energies (Tp=1520, 1805 and 2100 MeV), using the Saturne polarized proton beam and the SPES3 experimental facility. The analyzing powers of pp→Δ++Δ0, pp→Δ++n and pp→pπ+X reactions have been studied between 0° and 17° in the lab., which corresponds to an angular range between 0° and 100° (c.m.).

The tracking system of the ALICE dimuon spectrometer

The ALICE Muon Spectrometer is mainly dedicated to the measurement of the production of the J//spl psi/, and Y families through their decay into muon pairs, in Pb-Pb collisions. In this paper we give a description of the dimuon tracking system, mainly concentrating on the modular CSC chambers which occupy the last three stations. The R&D phase is now almost over and the production of the final modules started. A description of the main performances of the detectors based on test beam results on prototypes will be given.

p⃗p⇒Δ[sup ++]Δ[sup 0], p⃗p⇒Δ[sup ++]n and p⃗p⇒pπ[sup +]X reactions at energies between 1.5 and 2.1 GeV

The reaction p-vectorp{yields}p{pi}{sup +}X has been studied at three energies (T{sub p}=1520, 1805 and 2100 MeV), using the Saturne polarized proton beam and the SPES3 experimental facility. The analyzing powers of p-vectorp{yields}{delta}{sup ++}{delta}{sup 0}, p-vectorp{yields}{delta}{sup ++}n and p-vectorp{yields}p{pi}{sup +}X reactions have been studied between 0 deg. and 17 deg. in the lab., which corresponds to an angular range between 0 deg. and 100 deg. (c.m.)The reaction pp→pπ+X has been studied at three energies (Tp=1520, 1805 and 2100 MeV), using the Saturne polarized proton beam and the SPES3 experimental facility. The analyzing powers of pp→Δ++Δ0, pp→Δ++n and pp→pπ+X reactions have been studied between 0° and 17° in the lab., which corresponds to an angular range between 0° and 100° (c.m.).

p-vectorp{yields}{delta}{sup ++}{delta}{sup 0}, p-vectorp{yields}{delta}{sup ++}n and p-vectorp{yields}p{pi}{sup +}X reactions at energies between 1.5 and 2.1 GeV

The reaction p-vectorp{yields}p{pi}{sup +}X has been studied at three energies (T{sub p}=1520, 1805 and 2100 MeV), using the Saturne polarized proton beam and the SPES3 experimental facility. The analyzing powers of p-vectorp{yields}{delta}{sup ++}{delta}{sup 0}, p-vectorp{yields}{delta}{sup ++}n and p-vectorp{yields}p{pi}{sup +}X reactions have been studied between 0 deg. and 17 deg. in the lab., which corresponds to an angular range between 0 deg. and 100 deg. (c.m.)The reaction pp→pπ+X has been studied at three energies (Tp=1520, 1805 and 2100 MeV), using the Saturne polarized proton beam and the SPES3 experimental facility. The analyzing powers of pp→Δ++Δ0, pp→Δ++n and pp→pπ+X reactions have been studied between 0° and 17° in the lab., which corresponds to an angular range between 0° and 100° (c.m.).

Experimental Evidence of Narrow Non Strange Dibaryons

It is well known that experimental evidence for narrow dibaryons (i.e. states in the baryonic number B = 2 system) will be of major importance to point out quarks effects in nuclear physics. Many experiments have been undertaken these last years, to search for such strange and non strange structures. We will limit our discussion to non strange dibaryons and to narrow ones (the width of which is small compared to the width of the Δ resonance).