1,409 research outputs found
Two-loop QCD Corrections to Meson Leptonic Decays
The two-loop QCD radiative corrections to the meson leptonic decay rate
are calculated in the framework of NRQCD factorization formalism. Two types of
master integrals appearing in the calculation are obtained analytically for the
first time. We get the short-distance coefficient of the leading matrix element
to order by matching the full perturbative QCD calculation results
to the corresponding NRQCD ones. The result in this work helps the evaluation
of the leptonic decay constant, as well as the Cabibbo-Kobayashi-Maskawa
matrix element , to the full next-to-next-to-leading order degree of
accuracy.Comment: Typos are correcte
NNLO QCD Corrections to Exclusive Production in Electron-Positron Collision
Based on the NRQCD factorization formalism, we calculate the
next-to-next-to-leading order QCD corrections to the heavy quarkonium production associated with a photon at electron-positron colliders.
By matching the amplitudes calculated in full QCD theory to a series of
operators in NRQCD, the short-distance coefficients up to NNLO QCD radiative
corrections are determined. It turns out that the full set of master integrals
that we obtained could be analytically expressed in terms of Goncharov
Polylogarithms, Chen's iterated integrals, and elliptic functions, which mostly
do not exist in the literature and could be employed in the analyses of other
physical processes. In phenomenology, numerical calculations of NNLO K-factors
and cross sections of processes in
BESIII and B-factory experiments are performed, which may stand as a test of
the NRQCD higher order calculation while confronting to the data.Comment: 12 pages, 5 firue
Two-Loop integrals for CP-even heavy quarkonium production and decays: Elliptic Sectors
By employing the differential equations, we compute analytically the elliptic
sectors of two-loop master integrals appearing in the NNLO QCD corrections to
CP-even heavy quarkonium exclusive production and decays, which turns out to be
the last and toughest part in the relevant calculation. The integrals are found
can be expressed as Goncharov polylogarithms and iterative integrals over
elliptic functions. The master integrals may be applied to some other NNLO QCD
calculations about heavy quarkonium exclusive production, like
, ,~and~, heavy quarkonium exclusive
decays, and also the CP-even heavy quarkonium inclusive production and decays.Comment: 23 pages, 3 figures, more discussions and references adde
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