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D. Becirevic

Publications and source records attributed to D. Becirevic.

43 records · Page 3Linked to original sources
arXiv1999

Asymptotic scaling of the gluon propagtor on the lattice

We pursue the study of the high energy behaviour of the gluon propagator on the lattice in the Landau gauge in the flavorless case (n_f=0). It was shown in a precedin g paper that the gluon propagator did not reach three-loop asymptotic scaling at an energy scale as high as 5 GeV. Our present high statistics analysis includes also a simulation at $β=6.8$ ($a\simeq 0.03$ fm), which allows to reach $μ\simeq 10$ GeV. Special care has been devoted to the finite lattice-spacing artifacts as well as to the finite volume effects, the latter being acute at $β=6.8$ where the volume is bounded by technical limits. Our main conclusion is a strong evidence that the gluon propagator has reached three-loop asymptotic scaling, at $μ$ ranging from 5.6 GeV to 9.5 GeV. We buttress up this conclusion on several demanding criteria of asymptoticity, including scheme independence. Our fit in the 5.6 GeV to 9.5 GeV window yields $Λ^{\bar{\rm MS}} = 319 \pm 14 ^{+10}_{-20}$ MeV, in good agreement with our previous result, $Λ^{\bar{\rm MS}} = 295 \pm 20 $ MeV, obtained from the three gluon vertex, but it is significantly above the Schrödinger functional method estimate : $238 \pm 19$ MeV. The latter difference is not understood. Confirming our previous paper, we show that a fourth loop is necessary to fit the whole ($2.8 ÷9.5$) GeV energy window.

hep-ph↗
arXiv1999

Quark Masses and Renormalization Constants from Quark Propagator and 3-point Functions

We have computed the light and strange quark masses and the renormalization constants of the quark bilinear operators, by studying the large-p^2 behaviour of the lattice quark propagator and 3-point functions. The calculation is non-perturbatively improved, at O(a), in the chiral limit. The method used to compute the quark masses has never been applied so far, and it does not require an explicit determination of the quark mass renormalization constant.

hep-lat↗
arXiv1999

Gluon propagator, triple gluon vertex and the QCD coupling constant

We study the UV-scaling of the flavorless gluon propagator in the Landau gauge in an energy window up to 9 GeV. Dominant hypercubic lattice artifacts are eliminated. A large set of renormalization schemes is used to test asymptotic scaling. We compare with our results obtained directly from the triple gluon vertex. We end-up with Λ_{\bar{\rm{MS}}} = 318(12)(5) MeV and 292(5)(15) MeV respectively for these two methods, compatible which each other but significantly above the Schrodinger method estimate.

hep-lat↗
arXiv1998

Non-perturbatively Improved Heavy-Light Mesons: Masses and Decay Constants

We present a study of the heavy-light spectrum and of the D- and B-meson decay constants. The results wer e obtained in the quenched approximation, by using the non-perturbatively improved Clover lattice action at beta=6.2, with a sample of 100 configurations, on a 24^3 x 64 lattice. After a careful analysis of th e systematic errors present in the extraction of the physical results, by assuming quite conservative discretization errors, we find f_Ds=231 +/- 12^{+6}_{-1} MeV, f_D = 211 +/- 14^{+0}_{-12} MeV, f_Ds/f_D=1.10(2), f_Bs = 204 +/- 16^{+28}_{-0} MeV, f_B = 179 +/- 18^{+26}_{-9} MeV, f_Bs/f_B=1.14(3)^{+0}_{-1}. Our results, which have smaller discretization errors than many previous estimates at fixed value of the lattice spacing $a$, support a large value of f_B in the quenched approximation.

hep-lat↗
arXiv1998

Light hadron spectroscopy on the lattice with the non-perturbatively improved Wilson action

We present results for the light meson masses and decay constants as obtained from calculations with the non-perturbatively improved (`Alpha') action and operators on a 24^3 \times 64 lattice at beta = 6.2, in the quenched approximation. The analysis was performed in a way consistent with O(a) improvement. We obtained: reasonable agreement with experiment for the hyperfine splitting; f_K=156(17) MeV, f_pi =139(22) MeV, f_K/f_pi = 1.13(4) ; f_{K*}=219(7) MeV, f_rho =199(15) MeV, f_phi =235(4) MeV; f_{K*}^{T}(2 GeV) = 178(10) MeV, f_rho^{T}(2 GeV) =165(11) MeV, where f_V^{T} is the coupling of the tensor current to the vector mesons; the chiral condensate <\bar{q}q>^\bar{MS} (2 GeV)= - (253 +/- 25 MeV)^3. Our results are compared to those obtained with the unimproved Wilson action. We also verified that the free-boson lattice dispersion relation describes our results very accurately for a large range of momenta.

hep-lat↗
arXiv1998

Non-perturbatively Renormalized Light-Quark Masses with the Alpha Action

We have computed the light quark masses using the O(a^2) improved Alpha action, in the quenched approximation. The renormalized masses have been obtained non-perturbatively. By eliminating the systematic error coming from the truncation of the perturbative series, our procedure removes the discrepancies, observed in previous calculations, between the results obtained using the vector and the axial-vector Ward identities. It also gives values of the quark masses larger than those obtained by computing the renormalization constants using (boosted) perturbation theory. Our main results, in the RI (MOM) scheme and at a renormalization scale μ=2 GeV, are m^{RI}_s= 138(15) MeV and m^{RI}_l= 5.6(5) MeV, where m^{RI}_s is the mass of the strange quark and m^{RI}_l=(m^{RI}_u+m^{RI}_d)/2 the average mass of the up-down quarks. From these results, which have been obtained non-perturbatively, by using continuum perturbation theory we derive the \bar{MS} masses, at the same scale, and the renormalization group invariant (m^{RGI}) masses. We find m^{NLO \bar{MS}}_s= 121(13)$ MeV and m^{NLO\bar{MS}}_l= 4.9(4) MeV at the next-to-leading order; m^{N^2LO \bar{MS}}_s= 111(12) MeV, m^{N^2LO \bar{MS}}_l= 4.5(4) MeV, m_s^{RGI}= 177(19) MeV and m^{RGI}_l= 7.2(6) MeV at the next-to-next-to-leading order.

hep-lat↗