scholarly journals Determination of the Σ-Λ mixing angle from QCD sum rules

2016 ◽  
Vol 2016 (8) ◽  
Author(s):  
T. M. Aliev ◽  
T. Barakat ◽  
M. Savcı
Keyword(s):  
Sum Rules ◽  
Qcd Sum Rules ◽  
Mixing Angle

scholarly journals Improved determination of the mass of the1−+light hybrid meson from QCD sum rules

2003 ◽  
Vol 67 (1) ◽  
Author(s):  
H. Y. Jin ◽  
J. G. Körner ◽  
T. G. Steele
Keyword(s):  
Sum Rules ◽  
Hybrid Meson ◽  
Qcd Sum Rules

scholarly journals Determination of leading twist non-singlet operator matrix elements by QCD sum rules

1996 ◽  
Vol 380 (1-2) ◽  
pp. 151-158 ◽  
Author(s):  
G.G. Ross ◽  
N. Chamoun
Keyword(s):  
Sum Rules ◽  
Operator Matrix ◽  
Matrix Elements ◽  
Qcd Sum Rules

scholarly journals DETERMINATION OF LIGHT QUARK MASSES IN QCD

2010 ◽  
Vol 25 (29) ◽  
pp. 5223-5234 ◽  
Author(s):  
C. A. DOMINGUEZ
Keyword(s):  
Strange Quark ◽  
Sum Rules ◽  
Standard Procedure ◽  
Light Quark ◽  
Qcd Sum Rules ◽  
Quark Masses ◽  
Systematic Uncertainties ◽  
Better Than ◽  
The Ideal

The standard procedure to determine (analytically) the values of the quark masses is to relate QCD two-point functions to experimental data in the framework of QCD sum rules. In the case of the light quark sector, the ideal Green function is the pseudoscalar correlator which involves the quark masses as an overall multiplicative factor. For the past thirty years this method has been affected by systematic uncertainties originating in the hadronic resonance sector, thus limiting the accuracy of the results. Recently, a major breakthrough has been made allowing for a considerable reduction of these systematic uncertainties and leading to light quark masses accurate to better than 8%. This procedure will be described in this talk for the up-, down-, strange-quark masses, after a general introduction to the method of QCD sum rules.

scholarly journals Connections between chiral Lagrangians and QCD sum-rules

2016 ◽  
Vol 31 (03) ◽  
pp. 1650023 ◽  
Author(s):  
Amir H. Fariborz ◽  
A. Pokraka ◽  
T. G. Steele
Keyword(s):  
Chiral Lagrangians ◽  
Sum Rules ◽  
Chiral Symmetry Breaking ◽  
Vacuum Expectation ◽  
Qcd Sum Rules ◽  
Mixing Angle ◽  
Scalar Mesons ◽  
Scale Factors ◽  
Quark Level ◽  
Light Scalar

In this paper, it is shown how a chiral Lagrangian framework can be used to derive relationships connecting quark-level QCD correlation functions to mesonic-level two-point functions. Crucial ingredients of this connection are scale factor matrices relating each distinct quark-level substructure (e.g. quark–antiquark, four-quark) to its mesonic counterpart. The scale factors and mixing angles are combined into a projection matrix to obtain the physical (hadronic) projection of the QCD correlation function matrix. Such relationships provide a powerful bridge between chiral Lagrangians and QCD sum-rules that are particularly effective in studies of the substructure of light scalar mesons with multiple complicated resonance shapes and substantial underlying mixings. The validity of these connections is demonstrated for the example of the isotriplet [Formula: see text] system, resulting in an unambiguous determination of the scale factors from the combined inputs of QCD sum-rules and chiral Lagrangians. These scale factors lead to a remarkable agreement between the quark condensates in QCD and the mesonic vacuum expectation values that induce spontaneous chiral symmetry breaking in chiral Lagrangians. This concrete example shows a clear sensitivity to the underlying [Formula: see text]-system mixing angle, illustrating the value of this methodology in extensions to more complicated mesonic systems.

scholarly journals Determination of the up/down-quark mass within QCD sum rules in the scalar channel

2021 ◽  
Vol 81 (9) ◽  
Author(s):  
Fang-Hui Yin ◽  
Wen-Ya Tian ◽  
Liang Tang ◽  
Zhi-Hui Guo
Keyword(s):  
Monte Carlo ◽  
Quark Mass ◽  
Sum Rules ◽  
Light Quark ◽  
Spectral Functions ◽  
Qcd Sum Rules ◽  
Down Quark ◽  
Light Quark Mass ◽  
Data Group

AbstractIn this work, we determine up/down-quark mass $$m_{q=u/d}$$ m q = u / d in the isoscalar scalar channel from both the Shifman–Vainshtein–Zakharov (SVZ) and the Monte-Carlo-based QCD sum rules. The relevant spectral function, including the contributions from the $$f_0(500)$$ f 0 ( 500 ) , $$f_0(980)$$ f 0 ( 980 ) and $$f_0(1370)$$ f 0 ( 1370 ) resonances, is determined from a sophisticated U(3) chiral study. Via the traditional SVZ QCD sum rules, we give the prediction to the average light-quark mass $$m_q(2 ~\text {GeV})=\frac{1}{2}(m_u(2 ~\text {GeV}) + m_d(2 ~\text {GeV}))=(3.46^{+0.16}_{-0.22} \pm 0.33) ~\text {MeV}$$ m q ( 2 GeV ) = 1 2 ( m u ( 2 GeV ) + m d ( 2 GeV ) ) = ( 3 . 46 - 0.22 + 0.16 ± 0.33 ) MeV . Meanwhile, by considering the uncertainties of the input QCD parameters and the spectral functions of the isoscalar scalar channel, we obtain $$m_q (2~\text {GeV}) = (3.44 \pm 0.14 \pm 0.32) ~\text {MeV}$$ m q ( 2 GeV ) = ( 3.44 ± 0.14 ± 0.32 ) MeV from the Monte-Carlo-based QCD sum rules. Both results are perfectly consistent with each other, and nicely agree with the Particle Data Group value within the uncertainties.

scholarly journals Determination of the pion-nucleon coupling constant from QCD sum rules

1996 ◽  
Vol 373 (1-3) ◽  
pp. 9-15 ◽  
Author(s):  
Michael C. Birse ◽  
Boris Krippa
Keyword(s):  
Sum Rules ◽  
Coupling Constant ◽  
Qcd Sum Rules ◽  
Pion Nucleon
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