Zobrazeno 1 - 10
of 317
pro vyhledávání: '"Bernd A. Kniehl"'
Publikováno v:
Quantum Reports, Vol 5, Iss 1, Pp 198-223 (2023)
We consider a simple model for QCD dynamics in which DGLAP integro-differential equation may be solved analytically. This is a gauge model which possesses dominant evolution of gauge boson (gluon) distribution and in which the gauge coupling does not
Externí odkaz:
https://doaj.org/article/19701b91c228421baef19f49c9489080
Autor:
Bernd A. Kniehl, Oleg L. Veretin
Publikováno v:
Nuclear Physics B, Vol 992, Iss , Pp 116210- (2023)
We consider the renormalization of the three-quark operators without derivatives at next-to-next-to-leading order in QCD perturbation theory at the symmetric subtraction point. This allows us to obtain conversion factors between the MS‾ scheme and
Externí odkaz:
https://doaj.org/article/2d76f33ce9e149088df8e3d41af36187
Publikováno v:
Nuclear Physics B, Vol 992, Iss , Pp 116173- (2023)
We find the leading electroweak corrections to the Lagrangians of heavy-quark effective theory and nonrelativistic QCD. These corrections appear in the Wilson coefficients of the two- and four-quark operators and are considered here at one-loop order
Externí odkaz:
https://doaj.org/article/a2de446e79b94bf5a25490191abad43d
Publikováno v:
Nuclear Physics B, Vol 984, Iss , Pp 115972- (2022)
Starting from the Mellin–Barnes integral representation of a Feynman integral depending on a set of kinematic variables zi, we derive a system of partial differential equations w.r.t. new variables xj, which parameterize the differentiable constrai
Externí odkaz:
https://doaj.org/article/1dc604d0c79a45859679c2ff602213a5
Publikováno v:
Nuclear Physics B, Vol 937, Iss , Pp 533-549 (2018)
We consider the scalar sector of a general renormalizable theory and evaluate the effective potential through three loops analytically. We encounter three-loop vacuum bubble diagrams with up to two masses and six lines, which we solve using different
Externí odkaz:
https://doaj.org/article/50d55467559b44ec9aa32ae39d7427a9
Autor:
Mathias Butenschoen, Bernd A. Kniehl
Publikováno v:
Nuclear Physics B, Vol 957, Iss , Pp 115056- (2020)
We compare two approaches to evaluate cross sections of heavy-quarkonium production at next-to-leading order in nonrelativistic QCD involving S- and P-wave Fock states: the customary approach based on phase space slicing and the approach based on dip
Externí odkaz:
https://doaj.org/article/f6f4e080a59f4b3dbb2a69f6d0eee133
Autor:
Bernd A. Kniehl, Oleg L. Veretin
Publikováno v:
Physics Letters B, Vol 804, Iss , Pp - (2020)
We consider the renormalization of the matrix elements of the bilinear quark operators ψ¯ψ, ψ¯γμψ, and ψ¯σμνψ at next-to-next-to-next-to-leading order in QCD perturbation theory at the symmetric subtraction point. This allows us to obta
Externí odkaz:
https://doaj.org/article/35fb078001e743d6a311c44dc15d05c2
Autor:
Vladimir V. Bytev, Bernd A. Kniehl
Publikováno v:
Nuclear Physics B, Vol 952, Iss , Pp - (2020)
We consider the derivatives of Horn hypergeometric functions of any number of variables with respect to their parameters. The derivative of such a function of n variables is expressed as a Horn hypergeometric series of n+1 infinite summations dependi
Externí odkaz:
https://doaj.org/article/5d71b37e8a97451492b6c40c2231892b
Autor:
Mathias Butenschoen, Bernd A. Kniehl
Publikováno v:
Nuclear Physics B, Vol 950, Iss , Pp - (2020)
We describe an implementation of a subtraction scheme in the nonrelativistic-QCD treatment of heavy-quarkonium production at next-to-leading-order in the strong-coupling constant, covering S- and P-wave bound states. It is based on the dipole subtrac
Externí odkaz:
https://doaj.org/article/eeadc1af356a4fe0a5dd0ef2b2cfdcd4
Autor:
Ivan Gonzalez, Bernd A. Kniehl, Igor Kondrashuk, Eduardo A. Notte-Cuello, Ivan Parra-Ferrada, Marko A. Rojas-Medar
Publikováno v:
Nuclear Physics B, Vol 925, Iss , Pp 607-614 (2017)
In this paper, we proceed to study properties of MellinâBarnes (MB) transforms of UsyukinaâDavydychev (UD) functions. In our previous papers (Allendes et al., 2013 [13], Kniehl et al., 2013 [14]), we showed that multi-fold MellinâBarnes (MB) trans
Externí odkaz:
https://doaj.org/article/649ca17037e74f5a986fe3aaa164987f