摘要:

Preliminary results of search for exotic states in 1 GeV proton−nucleus collisions are presented. (AIP)

ISSN:0094-243X    

DOI:10.1063/1.40360

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Experimental search of nonstrange dibaryons in the c.m.s. energy range of 1.88 and 3.02 Gev is reviewed. (AIP)

ISSN:0094-243X    

DOI:10.1063/1.40361

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We study the structure and production of deeply bound pionic atoms in heavy nuclei, which are found quasi‐stable due to the repulsive pion‐nucleus optical potential and the attractive Coulomb potential. The bound pion forms a pionic halo just outside of nucleus. We discuss then the use of pion transfer reactions such as (n,p) and (d, 2He) to form these states. In addition, we study other processes such as (n,d) and (d, 3He) and the use of the inverse kinematics for formation of deeply bound pionic atoms.

ISSN:0094-243X    

DOI:10.1063/1.40362

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We propose to study pionic atoms in low‐lying states. The pions will be produced with the help of recoil free kinematics at small energies in the laboratory. A dedicated detector will be applied allowing the measurements of the width as well as the energy shift of these states.

ISSN:0094-243X    

DOI:10.1063/1.40363

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We discuss the short‐range structure of hadronic and nuclear wave functions expected in QCD. In addition to the ‘‘extrinsic’’ contributions associated with radiation from single partons, there is an ‘‘intrinsic’’ hardness of the high‐mass fluctuations of the wave function due to the spatial overlap of two or more partons.We argue that intrinsically‐hard partons, having large mass and/or large transverse momentum, will dominate in the region of large Feynman &khgr;F. Their rescattering in nuclear targets is expected to be larger than for extrinsically‐hard partons, leading to a suppressed production cross section for hadrons scattering on heavy nuclei. Experimental evidence for this exists for open charm,J/&psgr;, and &Ugr; production at large &khgr;F.The effects of intrinsic hardness may be particularly striking in nuclear wave functions, where the overlap of partons belonging to different nucleons can give rise to cumulative (x≳1) phenomena. The data on backward cumulative particle production from nuclei supports the existence of an intrinsically‐hard component in nuclear wave functions. Partons at largexFmay also be associated with the enhanced subthreshold production of particles observed in hadron‐nucleus and nucleus‐nucleus collisions.We discuss the evidence for anomalies in the large anglepp→ppcross section near the charm threshold. Arguments are presented that charmonium states may bind to nuclei through the QCD Van der Waals force. This would lead to a striking signal in charm production near threshold.

ISSN:0094-243X    

DOI:10.1063/1.40364

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We give a brief introduction to the nonrelativistic quark model and then present results from a coupled‐channel quark model analysis of light‐quarkS‐wave pseudoscalar‐pseudoscalar scattering and production processes. Annihilation mixing tos‐channelqq¯ scalar resonances and quark exchange interactions are found to be important. Contributions from the exchange oft‐channel mesons are not required to obtain agreement with the data. Intermeson forces are important in all channels and, in particular, lead to isospin 0 and 1KK¯ bound states analogous to the deuteron; we identify these with theS* (975) and &dgr;(980) scalar resonances.

ISSN:0094-243X    

DOI:10.1063/1.40365

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We investigate within a genrealized meson–exchange model meson–meson and meson–baryon scattering. We concentrate our investigations on the behavior of such systems when a new particle channel opens. Specifically we demonstrate these effects at the KK¯‐threshold in &pgr;&pgr;‐scattering and the K¯N‐threshold in &pgr;&Sgr;–scattering.

ISSN:0094-243X    

DOI:10.1063/1.40366

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We have used a model for the &eegr;N→&eegr;N interaction based on the dominance of the N*(1535) pole [1] and from it we have derived the &eegr; nucleus optical potential and investigated the bound states of &eegr; in nuclei and their decay width. The work follows closely the delta‐hole model used to study pion nucleus interaction around resonance [2].

ISSN:0094-243X    

DOI:10.1063/1.40367

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We have investigated several reactions in order to produce deeply bound pionic states so far unobserved. These are states like the ls or 2p in the Pb region for which standard potentials provide widths which are smaller than the separation beween the levels. This is particularly true of a new potential which solves the anomalies in the pionic atoms.

ISSN:0094-243X    

DOI:10.1063/1.40368

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The question whether an &eegr;NNquasi‐bound state exists is theoretically investigated. One solves the three‐body equation for the &pgr;NNand &eegr;NNcoupled systems. The coupling occurs through theS11resonance which connects with both the &pgr;Nand &eegr;Nchannels. One finds a pole structure near &eegr;NNthreshold (&sqrt;s=2430 MeV) in theI=0, JP=1−&eegr;dscattering amplitude.

ISSN:0094-243X    

DOI:10.1063/1.40382

出版商:AIP    

年代:1991

数据来源: AIP