Extracting infrared QCD coupling from meson spectrum
نویسندگان
چکیده
In the framework of the Bethe-Salpeter formalism used in previous papers to evaluate the quarkonium spectrum, here we reverse the point of view to extract an “experimental” running coupling α s (Q2) in the infrared (IR) region from the data. The values so obtained agree within the erros with the Shirkov-Solovtsov analytic coupling for 200 MeV < Q < 1.2 GeV, thus giving a very satisfactory unifying description of high and low energy phenomena. Below 1 GeV however α s (Q2) seems to vanish as Q → 0 . The paper is based on a work in progress in collaboration with D. V. Shirkov.
منابع مشابه
Suppression of πNN ( 1535 ) Coupling in the QCD Sum Rule
The πN N * and ηN N * coupling constants are studied in the QCD sum rule (N * ≡ N (1535)). We investigate the two point functions between the vacuum and a one meson state in the soft meson limit, extracting the contributions from N (1535) in the way we have formulated previously. The operator product expansion is performed up to the terms of dimension eight. We find that g πN N * vanishes to th...
متن کاملMeson Elastic and Transition Form Factors
The Dyson–Schwinger equations of QCD, truncated to ladder-rainbow level, are used to calculate meson form factors in impulse approximation. The infrared strength of the ladder-rainbow kernel is described by two parameters fitted to the chiral condensate and fπ; the ultraviolet behavior is fixed by the QCD running coupling. This obtained elastic form factors Fπ(Q) and FK(Q ) agree well with the ...
متن کاملVub from the Hadronic Invariant Mass Spectrum in Semileptonic B Decay
The hadronic invariant mass spectrum for the inclusive charmless semileptonic decay B → Xu e ν̄e is studied. Particular attention is paid to the region sH < mD, which may be useful for extracting the value of |Vub|. The sensitivity of the spectrum to the parameter Λ̄ ≡ mB − mb is explored. Perturbative QCD corrections to dΓ/dsH of order α 2 sβ0 are calculated. For sH ∼ Λ̄mb nonperturbative QCD eff...
متن کاملQCD coupling below 1 GeV from quarkonium spectrum
In this paper we exploit calculations within a Bethe-Salpeter (BS) formalism adjusted for QCD, in order to extract an “experimental” strong coupling α s (Q2) below 1 GeV by comparison with the meson spectrum. The BS potential follows from a proper ansatz on the Wilson loop to encode confinement and is the sum of a one-gluonexchange and a confinement term. Besides, the common perturbative strong...
متن کاملMeson B fragmentation function with consideration of mass corrections
Study of B meson (meson with the bottom quark flavor) in Large Hadron Collider (LHC) is of special importance so that the detector LHCb is devoted to investigate these types of mesons. For this reason, in this paper we will study the production process of this meson in a phenomenological approach using the experimental data from electron-positron annihilation. In this regards, we shall calculat...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2006