Search results for "cD [Galaxies]"
showing 10 items of 104 documents
B meson decay constants f B c $$ {f}_{B_c} $$ , f B s $$ {f}_{B_s} $$ and f B from QCD sum rules
2014
Finite energy QCD sum rules with Legendre polynomial integration kernels are used to determine the heavy meson decay constant f B c $$ {f}_{B_c} $$ , and revisit f B and f B s $$ {f}_{B_s} $$ . Results exhibit excellent stability in a wide range of values of the integration radius in the complex squared energy plane, and of the order of the Legendre polynomial. Results are f B c $$ {f}_{B_c} $$ = 528 ± 19 MeV, f B = 186 ± 14 MeV, and f B s $$ {f}_{B_s} $$ = 222 ± 12 MeV.
Calculation of the kaon B parameter using strictly local sum rules
1991
The kaon B-parameter is computed in the framework of strictly local QCD sum rules for a threepoint function involving pseudoscalar currents. As an application of these sum rules we derive a low energy formula for the B-parameter. We show that strictly local QCD sum rules yield more reliable results than other QCD sum rules, since they need less phenomenological information and do not suffer from stability problems. Our result for the B-parameter isB=0.74±0.17.
Decays of new nuclides and isomers beyond the proton drip line - The influence of neutron configurations
2008
Bozok University;Erciyes University;et al.;Istanbul University;Nigde University;The Turkish Atomic Energy Authority (TAEK)
Study of the D*ρ system using QCD sum rules
2013
In this talk I present a study of the $D^* \rho$ system made by using the method of QCD sum rules. Considering isospin and spin projectors, we investigate the different configurations and obtain three $D^*$ mesons with isospin $I=1/2$, spin $S=0$, $1$, $2$ and with masses $2500\pm 67$ MeV, $2523\pm60$ MeV, and $2439\pm119$ MeV, respectively. The last state can be related to $D^*_2(2460)$ (spin 2) listed by the Particle Data Group, while one of the first two might be associated with $D^*(2640)$, whose spin-parity is unknown. In the case of $I=3/2$ we also find evidences of three states with spin 0, 1 and 2, respectively, with masses $2467\pm82$ MeV, $2420\pm128$ MeV, and $2550\pm56$ MeV.
Up and down quark masses from Finite Energy QCD sum rules to five loops
2008
The up and down quark masses are determined from an optimized QCD Finite Energy Sum Rule (FESR) involving the correlator of axial-vector divergences, to five loop order in Perturbative QCD (PQCD), and including leading non-perturbative QCD and higher order quark mass corrections. This FESR is designed to reduce considerably the systematic uncertainties arising from the (unmeasured) hadronic resonance sector, which in this framework contributes less than 3-4% to the quark mass. This is achieved by introducing an integration kernel in the form of a second degree polynomial, restricted to vanish at the peak of the two lowest lying resonances. The driving hadronic contribution is then the pion …
Can we understand an auxetic pion-photon transition form factor within QCD?
2013
A state-of-the-art analysis of the pion-photon transition form factor is presented based on an improved theoretical calculation that includes the effect of a finite virtuality of the quasireal photon in the method of light-cone sum rules. We carry out a detailed statistical analysis of the existing experimental data using this method and by employing pion distribution amplitudes with up to three Gegenbauer coefficients a(2), a(4), a(6). Allowing for an error range in the coefficient a(6) approximate to 0, the theoretical predictions for gamma*gamma -> pi(0) obtained with nonlocal QCD sum rules are found to be in good agreement with all data that support a scaling behavior of the transition …
Pentaquark and diquark–diquark clustering: a QCD sum rule approach
2004
In this work we study the Theta(1540) in the framework of QCD sum rules based on (ud)^2\bar{s} diquark clustering as suggested by Jaffe and Wilczek. Within errors, the mass of the pentaquark is compatible with the experimentally measured value. The mass difference between the Theta and the pentaquark with the quantum numbers of the nucleon amounts to 70 MeV, consistent with the interpretation of the N(1440) as a pentaquark.
QCD sum rules for heavy baryons
2001
We construct the heavy baryonic currents by using the Bethe-Salpeter wave functions in the heavy quark limit. We discuss the one-loop renormalization of these heavy baryonic currents as well as their two-point correlators up to the order $1/M_h$. For a special case, we do the QCD sum rule for masses of the doublet (3/2,5/2).
Strange quark condensate from QCD sum rules to five loops
2007
It is argued that it is valid to use QCD sum rules to determine the scalar and pseudoscalar two-point functions at zero momentum, which in turn determine the ratio of the strange to non-strange quark condensates $R_{su} = \frac{}{}$ with ($q=u,d$). This is done in the framework of a new set of QCD Finite Energy Sum Rules (FESR) that involve as integration kernel a second degree polynomial, tuned to reduce considerably the systematic uncertainties in the hadronic spectral functions. As a result, the parameters limiting the precision of this determination are $\Lambda_{QCD}$, and to a major extent the strange quark mass. From the positivity of $R_{su}$ there follows an upper bound on the latt…
Light quark condensates from QCD sum rules
1985
The light quark condensates have been determined by two different methods: By Laplace transformed QCD sum rules together with an improved hadronic continuum from extended PCAC and by analytic continuation by duality (ACD) of the asymptotic QCD amplitude. Both methods yield compatible results. The PCAC corrections are considerably large: for theu, d quarks near 8% and for theu, s quarks of order 60%.