Two Topics in QCD Sum-Rules: Bounds on Light Quark and Scalar Gluonium Masses
نویسنده
چکیده
QCD Laplace sum-rules are briefly reviewed and two sum-rule applications are presented. For scalar gluonium, upper bounds on the lightest state are obtained from ratios of Laplace sum-rules, and the role of instantons and the low-energy theorem on these bounds is investigated. For the light-quark masses, fundamental inequalities for Laplace sum-rules are developed, which lead to a lower bound on the average of the up and down quark masses.
منابع مشابه
Near-Maximal Mixing of Scalar Gluonium and Quark Mesons: A Gaussian Sum-Rule Analysis
Gaussian QCD sum-rules are ideally suited to the study of mixed states of gluonium (glueballs) and quark (qq̄) mesons because of their capability to resolve widely-separated states of comparable strength. The Gaussian QCD sum-rules (GSRs) for all possible two-point correlation functions of gluonic and non-strange I = 0 quark scalar (J = 0) currents are calculated and analyzed. For the non-diagon...
متن کاملGaussian Sum-Rule Analysis of Scalar Gluonium and Quark Mesons
Gaussian sum-rules, which are related to a two-parameter Gaussian-weighted integral of a hadronic spectral function, are able to examine the possibility that more than one resonance makes a significant contribution to the spectral function. The Gaussian sum-rules, including instanton effects, for scalar gluonic and non-strange scalar quark currents clearly indicate a distribution of the resonan...
متن کاملQCD Sum-Rule Bounds on the Light Quark Masses
QCD sum-rules are related to an integral of a hadronic spectral function, and hence must satisfy integral inequalities which follow from positivity of the spectral function. Development of these Hölder inequalities and their application to the Laplace sum-rule for pions lead to a lower bound on the average of the non-strange 2GeV light-quark masses in the MS scheme. The light quark masses are f...
متن کاملEstimates of Light Quark Masses from Lattice QCD and QCD Sum rules
This talk reviews the progress made in the determination of the light quark masses using lattice QCD and QCD sum rules. Based on preliminary calculations with three flavors of dynamical quarks, the lattice estimate is ms = 75(15) MeV, a tantalizingly low value. On the other hand the leading estimates from scale and pseudo-scalar sum rules are 99(16) and 100(12) MeV respectively. The τ -decay su...
متن کاملTrigluon Glueball and its Implication for a Recent BES Observation
We calculate the mass of the 0 triple-valence-gluon resonance, the trigluon glueball, by virtue of the QCD sum rules. Result shows that the mass of the trigluon glueball lies in between 1.9 and 2.7 GeV within the scope of theoretical uncertainties. Moreover, it is likely that the BES new measurement of the pp̄ enhancement near threshold in the J/ψ decays exhibits the existence of this trigluon s...
متن کامل