scholarly journals QUARK MASSES IN QCD: A PROGRESS REPORT

2011 ◽  
Vol 26 (10) ◽  
pp. 691-710 ◽  
Author(s):  
C. A. DOMINGUEZ
Keyword(s):  
Heavy Quark ◽  
Light Quark ◽  
Finite Energy ◽  
Experimental Information ◽  
Spectral Functions ◽  
Quark Masses ◽  
Quark Sector ◽  
Vector Channel ◽  
Systematic Uncertainties ◽  
Improved Accuracy

Recent progress on QCD sum rule determinations of the light and heavy quark masses is reported. In the light quark sector a major breakthrough has been made recently in connection with the historical systematic uncertainties due to a lack of experimental information on the pseudoscalar resonance spectral functions. It is now possible to suppress this contribution to the 1% level by using suitable integration kernels in Finite Energy QCD sum rules. This allows one to determine the up-, down-, and strange-quark masses with an unprecedented precision of some 8–10%. Further reduction of this uncertainty will be possible with improved accuracy in the strong coupling, now the main source of error. In the heavy quark sector, the availability of experimental data in the vector channel, and the use of suitable multipurpose integration kernels allows one to increase the accuracy of the charm- and bottom-quarks masses to the 1% level.

Quark mass determinations in QCD

2014 ◽  
Vol 29 (28) ◽  
pp. 1430031 ◽  
Author(s):  
C. A. Dominguez
Keyword(s):  
Heavy Quark ◽  
Light Quark ◽  
Finite Energy ◽  
Experimental Information ◽  
Bottom Quarks ◽  
Spectral Functions ◽  
Quark Masses ◽  
Quark Sector ◽  
Vector Channel ◽  
Systematic Uncertainties

Recent progress on QCD sum rule determinations of the light and heavy quark masses is reported. In the light quark sector a major breakthrough has been made recently in connection with the historical systematic uncertainties due to a lack of experimental information on the pseudoscalar resonance spectral functions. It is now possible to suppress this contribution to the 1% level by using suitable integration kernels in Finite Energy QCD sum rules. This allows to determine the up-, down-, and strange-quark masses with an unprecedented precision of some 8–10%. In the heavy quark sector, the availability of experimental data in the vector channel, and the use of suitable multipurpose integration kernels allows to increase the accuracy of the charm- and bottom-quarks masses to the 1% level.

scholarly journals Meson Mass Spectrum from First Order Static Cavity Wavefunctions

1989 ◽  
Vol 42 (5) ◽  
pp. 471
Author(s):  
Lloyd CL Hollenberg ◽  
Bruce HJ McKellar
Keyword(s):  
Mass Spectrum ◽  
Heavy Quark ◽  
Ground State ◽  
Light Quark ◽  
Meson Mass ◽  
Meson Spectrum ◽  
First Order ◽  
Quark Masses ◽  
Quark Sector ◽  
Meson Mass Spectrum

Large-basis O(g) static cavity wavefunctions, containing bremsstrahlung and quark-sea states, previously fitted to the light quark meson sector, are applied to the ground-state meson spectrum in general. The only parameters of the model in the heavy quark sector are the quark masses me and mb which we fit to D and B states. Predictions for the meson mass spectrum are given and are found to be a significant improvement over the predictions of the original. MIT model.

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 AN ANALYTIC METHOD OF DESCRIBING R-RELATED QUANTITIES IN QCD

2006 ◽  
Vol 21 (17) ◽  
pp. 1355-1368 ◽  
Author(s):  
K. A. MILTON ◽  
I. L. SOLOVTSOV ◽  
O. P. SOLOVTSOVA
Keyword(s):  
Light Quark ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Analytic Method ◽  
Suggested Model ◽  
Quark Masses ◽  
Vector Channel ◽  
Hadronic Contribution ◽  
Decay Widths ◽  
Physical Quantities

A model based on the analytic approach to QCD, involving a summation of threshold singularities and taking into account the nonperturbative character of the light quark masses, is applied to find hadronic contributions to different physical quantities. It is shown that the suggested model allows us to describe well such objects as the hadronic contribution to the anomalous magnetic moment of the muon, the ratio of hadronic to leptonic τ-decay widths in the vector channel, the Adler D-function, the smeared RΔ-function, and the hadronic contribution to the evolution of the fine structure constant.

Finite-energy sum rules and light-quark masses

1983 ◽  
Vol 76 (4) ◽  
pp. 723-733 ◽  
Author(s):  
A. L. Kataev ◽  
N. V. Krasnikov ◽  
A. A. Pivovarov
Keyword(s):  
Sum Rules ◽  
Light Quark ◽  
Finite Energy ◽  
Quark Masses

LIGHT QUARK MASSES FROM QCD SUM RULES

2013 ◽  
Vol 28 (26) ◽  
pp. 1360016 ◽  
Author(s):  
KARL SCHILCHER
Keyword(s):  
Quark Mass ◽  
Strange Quark ◽  
Sum Rules ◽  
Light Quark ◽  
Finite Energy ◽  
Qcd Sum Rules ◽  
Sum Rule ◽  
Quark Masses ◽  
Strange Quark Mass

Recent QCD sum rule determinations of the light quark masses are reviewed. In the case of the strange quark mass, possible uncertainties are discussed in the framework of finite energy sum rules.

scholarly journals Test of the Chiral Structure and FCNC in the Quark Sector by Radiative B Meson Decays

1997 ◽  
Vol 12 (31) ◽  
pp. 5609-5624 ◽  
Author(s):  
L. T. Handoko ◽  
T. Yoshikawa
Keyword(s):  
B Meson ◽  
Light Quark ◽  
Experimental Results ◽  
Fourth Generation ◽  
Natural Assumption ◽  
Chiral Structure ◽  
B Meson Decays ◽  
Meson Decays ◽  
Quark Masses ◽  
Quark Sector

We study the effects of a vector-like SU(2) quark doublet as a fourth generation. In this model we examine the chiral structure and the FCNC in the quark sector by using radiative B meson decays in the allowed region for parameters from Rb = Γqq/Γ had . We compute the ratio R = Br (b → dγ)/ Br (b → sγ) in the model which realizes a different chiral structure as well as FCNC. The constraints have been extracted from the experimental results of B meson decays, the T new parameter of oblique corrections and Rb. Under the natural assumption that the violation of the V - A structure in the light-quark sector is small, we can determine the allowed region for most of the mixings parameters and the vector-like quark masses. We show that there will be significant deviations in R from the SM prediction due to the FCNC's and the violation of the V - A structure.

scholarly journals Light meson form factors at high Q2 from lattice QCD

2018 ◽  
Vol 175 ◽  
pp. 06015 ◽  
Author(s):  
Jonna Koponen ◽  
André Zimermmane-Santos ◽  
Christine Davies ◽  
G. Peter Lepage ◽  
Andrew Lytle
Keyword(s):  
Lattice Qcd ◽  
Theoretical Calculations ◽  
Light Quark ◽  
Form Factors ◽  
Hadron Structure ◽  
Strange Quarks ◽  
Pion Scattering ◽  
Quark Masses ◽  
Systematic Uncertainties ◽  
Atomic Electrons

Measurements and theoretical calculations of meson form factors are essential for our understanding of internal hadron structure and QCD, the dynamics that bind the quarks in hadrons. The pion electromagnetic form factor has been measured at small space-like momentum transfer |q2| < 0.3 GeV2 by pion scattering from atomic electrons and at values up to 2.5 GeV2 by scattering electrons from the pion cloud around a proton. On the other hand, in the limit of very large (or infinite) Q2 = −q2, perturbation theory is applicable. This leaves a gap in the intermediate Q2 where the form factors are not known. As a part of their 12 GeV upgrade Jefferson Lab will measure pion and kaon form factors in this intermediate region, up to Q2 of 6 GeV2. This is then an ideal opportunity for lattice QCD to make an accurate prediction ahead of the experimental results. Lattice QCD provides a from-first-principles approach to calculate form factors, and the challenge here is to control the statistical and systematic uncertainties as errors grow when going to higher Q2 values. Here we report on a calculation that tests the method using an ηs meson, a ’heavy pion’ made of strange quarks, and also present preliminary results for kaon and pion form factors. We use the nf = 2 + 1 + 1 ensembles made by the MILC collaboration and Highly Improved Staggered Quarks, which allows us to obtain high statistics. The HISQ action is also designed to have small dicretisation errors. Using several light quark masses and lattice spacings allows us to control the chiral and continuum extrapolation and keep systematic errors in check.

scholarly journals Insight into Thermal Modifications of Quarkonia From a Comparison of Continuum-Extrapolated Lattice Results to Perturbative QCD

Proceedings ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 45 ◽  
Author(s):  
Anna-Lena Kruse ◽  
H.-T. Ding ◽  
O. Kaczmarek ◽  
H. Ohno ◽  
H. Sandmeyer
Keyword(s):  
Heavy Quark ◽  
Spectral Function ◽  
Bound States ◽  
Low Frequency ◽  
Vector Channel ◽  
Systematic Uncertainties ◽  
Integration Kernel ◽  
Frequency Regime ◽  
Ill Posed ◽  
Insight Into

In this work, we strive to gain insight into thermal modifications of charmonium and bottomonium bound states as well as the heavy quark diffusion coefficient. The desired information is contained in the spectral function which can not be calculated on the lattice directly. Instead, the correlator given by an integration over the spectral function times an integration kernel is obtained. Extracting the spectral function is an ill-posed inversion problem and various different solutions have been proposed. We focus on a comparison to a spectral function obtained from combining perturbative and pNRQCD calculations. In order to get precise results, continuum extrapolated correlators originating from large and fine lattices are used. We first analyze the pseudoscalar channel since the absence of a transport peak simplifies the analysis. The knowledge gained from this is then used to extend the analysis to the vector channel, where information on heavy quark transport is encoded in the low frequency regime of the spectral function. The comparison shows a qualitatively good agreement between perturbative and lattice correlators. Quantitative differences can be explained by systematic uncertainties.

Sign in / Sign up

Export Citation Format

Share Document