Transverse spin of quarks inside the baryon
Creators
- 1. Lyon-1 Univ., 69 - Villeurbanne (France). Inst. de Physique Nucleaire
- 2. Paris-11 Univ., 91 - Orsay (France). Inst. Universitaire de Technologie
Description
We give a brief survey ot the effects of transverse polarisation of quarks in a polarized baryon. The quark transverse polarisation is related to the exchange of a qantiq state of total helicity ±1 in the t-channel (this last channel refers to the forward amplitude whose discontinuity in s equals the cross section). This link helps us to select processes where transverse polarisation assymmetries appear at leading order in 1/Q2 and αs, namely qq or qantiq collisions in experiments with polarized beam and target. Two examples are proposed, which are (i) lepton pair creation by polarised antiprotons against polarised protons, (ii) inclusive hadron production at large pT. The transversally polarized quark distibution Δ1q(x,Q2) evolves according to an Altarelli-Parisi equation, with no coupling to the gluonic distributions; it decreases logarithmically. We show on a simplified model of the baryon that Δ1q may be large. By the way, this model shows that the total helicity of the quark is not necessarily of the same sign as the baryon helicity
Availability note (English)
MF available from INIS under the Report Number.Abstract (French)
Nous donnons un apercu des effets de polarisation transverse des quarks dans un baryon polarise transversalement. La polarisation transverse d'un quark est reliee a l'echange d'un etat qantiq d'helicite totale ±1 dans la voie t (celle-ci se rapporte a l'amplitude vers l'avant dont la discontinuite en s est egale a la section efficace). Ce lien nous permet de selectionner les processus ou des assymetries de polarisation transverses apparaitront a l'ordre dominant en 1/Q2 et αs, a savoir les collisions qq ou qantiq dans les experiences avec faisceau et cible polarises. Deux exemples proposes sont (i) la creation de paires de leptons par des antiprotons polarises sur des protons polarises, (ii) la production inclusive de hadrons a grand pT. La distribution de polarisation transverse Δ1q(x, Q2) evolue selon une equation d'Altarelli-Parisi non couplee avec les distributions gluoniques; elle decroit logarithmiquement. Nous montrons, avec un modele simplifie du baryon, qu'elle peut etre importante. Ce modele montre en passant que l'helicite totale des quarks n'est pas forcement de meme signe que celle du baryonFiles
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Additional details
Additional titles
- Original title (French)
- Spin transverse des quarks dans les baryons
Publishing Information
- Imprint Pagination
- 7 p.
- Report number
- LYCEN--9006
Conference
- Title
- Electromagnetic and weak sounds in nuclear physics. 3. J. Cartier Talks.
- Original Conference Title
- Colloque: Sondes Electromagnetiques et faibles en Physique Nucleaire, 3. Entretiens Jacques Cartier
- Dates
- 6-8 Dec 1989.
- Place
- Lyon (France).
INIS
- Country of Publication
- France
- Country of Input or Organization
- France
- INIS RN
- 22053924
- Subject category
- S72: PHYSICS OF ELEMENTARY PARTICLES AND FIELDS;
- Resource subtype / Literary indicator
- Conference
- Descriptors DEI
- BARYONS; DENSITY MATRIX; HELICITY; INELASTIC SCATTERING; POLARIZATION-ASYMMETRY RATIO; POLARIZED BEAMS; POLARIZED TARGETS; QUARK-ANTIQUARK INTERACTIONS; QUARKS; SPIN ORIENTATION; STRUCTURE FUNCTIONS; TRANSVERSE MOMENTUM
- Descriptors DEC
- BEAMS; ELEMENTARY PARTICLES; FERMIONS; FUNCTIONS; HADRONS; INTERACTIONS; LINEAR MOMENTUM; MATRICES; ORIENTATION; PARTICLE INTERACTIONS; PARTICLE PROPERTIES; POSTULATED PARTICLES; SCATTERING; TARGETS