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Chiral Symmetry Restoration in Hadron Spectra *
| Content Provider | Semantic Scholar |
|---|---|
| Author | Glozman, L. Ya. |
| Abstract | The evidence and the theoretical justification of chiral symmetry restoration in high-lying hadrons is presented. It has recently been suggested that the parity doublet structure seen in the spectrum of highly excited baryons may be due to effective chiral symmetry restoration for these states [1]. This phenomenon can be understood in very general terms from the validity of the operator product expansion (OPE) in QCD at large space-like momenta and the validity of the dispersion relation for the two-point correlator, which connects the spacelike and timelike regions (i.e. the validity of Källen-Lehmann representation) [2,3]. Consider a two-point correlator Π Jα of the current J α (x) (that creates from the vacuum the hadrons with the quantum numbers α) at large spacelike momenta Q 2 , where the language of quarks and gluons is adequate and where the OPE is valid. The only effect that chiral symmetry breaking can have on the correlator is through the nonzero value of conden-sates associated with operators which are chirally active (i.e. which transform nontrivially under chiral transformations). To these belong ¯ qq and higher dimensional condensates that are not invariant under axial transformation. At large Q 2 only a small number of con-densates need be retained to get an accurate description of the correlator. Contributions of these condensates are suppressed by inverse powers of Q 2. At asymptotically high Q 2 , the correlator is well described by a single term—the perturbative term. The essential thing to note from this OPE analysis is that the perturbative contribution knows nothing about chiral symmetry breaking as it contains no chirally nontrivial condensates. In other words, though the chiral symmetry is broken in the vacuum and all chiral noninvariant condensates are not zero, their influence on the correlator at asymptotically high Q 2 vanishes. This is in contrast to the situation of low values of Q 2 , where the role of chiral condensates is crucial. This shows that at large spacelike momenta the correlation function becomes chirally symmetric. In other words, two correlators Π J 1 (Q 2) and Π J 2 (Q 2), where J 1 = UJ 2 U † , |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://arxiv.org/pdf/hep-ph/0210216v1.pdf |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Arabic numeral 0 Chirality (chemistry) Circuit restoration Cross-correlation Emoticon Microencapsulated Potassium Chloride 20 MEQ Extended Release Oral Tablet [Klor-Con] Naruto Shippuden: Clash of Ninja Revolution 3 Perturbation theory (quantum mechanics) Power (Psychology) Quantum number RCA Spectra 70 Symmetry breaking Telling untruths Units of information cell transformation phosphoethanolamine |
| Content Type | Text |
| Resource Type | Article |
