TY - JOUR

T1 - Beyond leading-order corrections to [Formula Presented] at large [Formula Presented] The charged-Higgs-boson contribution

AU - Borzumati, Francesca

AU - Greub, Christoph

AU - Yamada, Youichi

PY - 2004/1/1

Y1 - 2004/1/1

N2 - Among the [Formula Presented] contributions to the Wilson coefficients [Formula Presented] and [Formula Presented] relevant for the decay [Formula Presented] those induced by two-loop diagrams with charged-Higgs-boson exchange and squark-gluino corrections are calculated in supersymmetric models at large [Formula Presented] The calculation of the corresponding Feynman integrals is exact, unlike in previous studies that are valid when the typical supersymmetric scale [Formula Presented] is sufficiently larger than the electroweak scale [Formula Presented] and the mass of the charged Higgs boson [Formula Presented] Therefore, the results presented here can be used for any value of the various supersymmetric masses. These results are compared with those of an approximate calculation, already existing in the literature, that is at the zeroth order in the expansion parameter [Formula Presented] and with the results of two new approximate calculations in which the first and second order in the same expansion parameter are retained, respectively. This comparison allows us to assess whether the results of these three approximate calculations can be extended beyond the range of validity for which they were derived, i.e., whether they can be used for [Formula Presented] and/or [Formula Presented] It is found that the zeroth-order approximation works well even for [Formula Presented] provided [Formula Presented] The inclusion of the higher-order terms improves the zeroth-order approximation for [Formula Presented] but it worsens it for [Formula Presented].

AB - Among the [Formula Presented] contributions to the Wilson coefficients [Formula Presented] and [Formula Presented] relevant for the decay [Formula Presented] those induced by two-loop diagrams with charged-Higgs-boson exchange and squark-gluino corrections are calculated in supersymmetric models at large [Formula Presented] The calculation of the corresponding Feynman integrals is exact, unlike in previous studies that are valid when the typical supersymmetric scale [Formula Presented] is sufficiently larger than the electroweak scale [Formula Presented] and the mass of the charged Higgs boson [Formula Presented] Therefore, the results presented here can be used for any value of the various supersymmetric masses. These results are compared with those of an approximate calculation, already existing in the literature, that is at the zeroth order in the expansion parameter [Formula Presented] and with the results of two new approximate calculations in which the first and second order in the same expansion parameter are retained, respectively. This comparison allows us to assess whether the results of these three approximate calculations can be extended beyond the range of validity for which they were derived, i.e., whether they can be used for [Formula Presented] and/or [Formula Presented] It is found that the zeroth-order approximation works well even for [Formula Presented] provided [Formula Presented] The inclusion of the higher-order terms improves the zeroth-order approximation for [Formula Presented] but it worsens it for [Formula Presented].

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U2 - 10.1103/PhysRevD.69.055005

DO - 10.1103/PhysRevD.69.055005

M3 - Article

AN - SCOPUS:85038994356

VL - 69

JO - Physical review D: Particles and fields

JF - Physical review D: Particles and fields

SN - 1550-7998

IS - 5

ER -