Proton spin content and QCD topological susceptibility

Ioffe, B.L.; Oganesian, A. G.

doi:10.1103/physrevd.57.r6590

Cited by 30 publications

(39 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The optimum value of τ −1 = 2.5 − 5 GeV 2 is in line with general arguments for the appropriate scale in the gluon-rich U A (1) channel. Specific criticisms [16][17][18][19][20] of the applicability of spectral sum rules to the U A (1) channel were shown to be incorrect.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Topological charge screening and the ‘proton spin’ beyond the chiral limit

1999

View full text Add to dashboard Cite

The theory of the 'proton spin' effect proposed in our earlier papers is extended to include the chiral SU (3) symmetry breaking and flavour mixing induced by non-vanishing quark masses in QCD. The theoretical basis is the derivation of exact, unified GoldbergerTreiman (GT) relations valid beyond the chiral limit. The observed suppression in the flavour singlet axial charge a 0 (Q 2 ) is explained by an anomalously small value for the slope of the singlet current correlation function 0|T|0 , a consequence of the screening of topological charge in the QCD vacuum. Numerical predictions are obtained by evaluating the current correlation functions using QCD spectral sum rules. The results, a 0 (Q 2 ) = 0.31 ± 0.02 and dx g p 1 (x, Q 2 ) = 0.141 ± 0.005 (at Q 2 = 10 GeV 2 ), are in good agreement with current experimental data on the polarised proton structure function g p 1 .

show abstract

Section: Discussionmentioning

confidence: 99%

“…[12] due to the change [39] in the O(α Since the validity of the spectral sum rules for calculating χ ′ (0) has been criticised in the literature by Ioffe [16,17] (see refs. [16][17][18][19][20] and our detailed rebuttal in Appendix D), we should emphasise some features of this derivation.…”

Section: 1mentioning

confidence: 99%

Topological charge screening and the ‘proton spin’ beyond the chiral limit

1999

View full text Add to dashboard Cite

show abstract

“…This negative sign is the fundamental reason for the observed smallness of the flavor singlet axial coupling constant of nucleon. The relation of the present consideration to the approach to the proton spin problem based on investigation of QCD topological susceptibility [47,48,49] will be the subject of forthcoming publication [50]. It would be also interesting to study the connection of X(1835) mechanism with the gluon contribution to the proton spin obtained within a chiral bag model [51], and the relation of this mechanism to the different approaches based on instanton contribution to proton spin [52,53,54].…”

Section: Resultsmentioning

confidence: 99%

X(1835) as the lowest mass pseudoscalar glueball and proton spin problem

Kochelev

Min

2006

Physics Letters B

View full text Add to dashboard Cite

We consider the parity doublet structure observed in high hadronic excitations within the instanton model for the QCD vacuum. In the conventional approach this doubling phenomenon is treated as a manifestation of the partial restoration of chiral or U (1) A symmetry. We demonstrate that the suppression of direct instanton contribution to the masses of excited hadrons leads to the partial U(1) A symmetry restoration in hadron spectrum. The origin of X(1835) resonance observed by BES Collaboration is studied upon the doublet structure. We argue also how X(1835) be interpreted as the lowest pseudoscalar glueball state, and derive its coupling constant to proton. It turns out that this coupling is large and negative. Demonstrated is how this large coupling affects the gluonic contribution to the proton spin.

show abstract

“…(20), since singlet axial current is not conserved by virtue of anomaly and the singlet pseudoscalar meson η ′ is not Goldstone one. Constant f 2 0 is proportional to topologicaal susceptibility of vacuum [23] …”

Section: (I)mentioning

confidence: 99%

Condensates in quantum chromodynamics

Ioffe

2003

Phys. Atom. Nuclei

Self Cite

View full text Add to dashboard Cite

The paper presents the short review of our to-day knowledge of vacuum condensates in QCD. The condensates are defined as vacuum averages of the operators which arise due to nonperturbative effects. The important role of condensates in determination of physical properties of hadrons and of their low-energy interactions in QCD is underlined. The special value of quark condensate, connected with the existence of baryon masses is mentioned. Vacuum condensates induced by external fields are discussed. QCD at low energy is checked on the basis of the data on hadronic τ -decay. In the theoretical analysis the terms of perturbation theory (PT) up to α 3 s are accounted, in the operator product expansion (OPE) -those up to dimension 8. The total probability of the decay τ → hadrons (with zero strangeness) and of the τ -decay structure functions are best described at α s (m 2 τ ) = 0.330 ± 0.025. It is shown that the Borel sum rules for τ -decay structure functions along the rays in the q 2 -complex plane are in agreement with the experiment with the accuracy ∼ 2% at the values of the Borel parameter |M 2 | > 0.8GeV 2 . The magnitudes of dimensions 6 and 8 condensates were found and the limitations on gluonic condensates were obtained. The sum rules for the charmed quark vector currents polarization operator was analysed in 3 loops (i.e., in order α 2 s ). The value of charmed quark mass (in MS regularization scheme) was found to be: m c (m c ) = 1.275 ± 0.015GeV and the value of gluonic condensate was estimated: 0|(α s /π)G 2 |0 = 0.009 ± 0.007GeV 4 . The general conclusion is: QCD described by PT + OPE is in a good agreement with experiment at Q 2 > ∼ 1GeV 2 .

show abstract

Proton spin content and QCD topological susceptibility

Cited by 30 publications

References 12 publications

Topological charge screening and the ‘proton spin’ beyond the chiral limit

Topological charge screening and the ‘proton spin’ beyond the chiral limit

X(1835) as the lowest mass pseudoscalar glueball and proton spin problem

Condensates in quantum chromodynamics

Contact Info

Product

Resources

About