Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · hep-ph/9910220

Photonic penguins at two loops and m_t-dependence of BR[ B -> X_s l^+ l^-]

Christoph Bobeth·Mikolaj Misiak·Joerg Urban
View original source ↗Read source document ↗Export metadata ↓

Abstract

We calculate two-loop matching conditions for all the operators that are relevant to B -> X_s l^+ l^- decay in the Standard Model. In effect, we are able to remove the +_16% uncertainty in the decay spectrum, which was mainly due to the renormalization-scale dependence of the top-quark mass. We find 1.46 * 10^-6 for the branching ratio integrated in the domain 0.05 < m_{l^+l^-}^2/m_b^2 < 0.25, for l= e or mu. There remains around 13% perturbative uncertainty in this quantity, while the non-perturbative effects are expected to be smaller.

Explore related subjects

hep-ph

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Christoph Bobeth, Mikolaj Misiak, Joerg Urban. 1999-10-04. Photonic penguins at two loops and m_t-dependence of BR[ B -> X_s l^+ l^-]. https://doi.org/10.1016/s0550-3213(00)00007-9

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Pomeron Weights in QCD Processes at High Energy and the $S$-Matrix Unitarity Constraint

The pomeron topological cross-section is derived for the eikonal and the $U$-matrix unitarization schemes using a generalized representation of the scattering amplitude at high energy in an effort to examine pomeron characteristics, namely the multiplicity distribution, fluctuation, and correlation, and to reveal the impact of pomeron weights on the $pp$ multiplicity distribution. The results demonstrate that the $U$-matrix inherently incorporates a larger amount of diffraction production into the multi-pomeron vertices, yielding a larger pomerons' variability regardless of the energy range, while such fluctuations become significant only beyond a specific high-energy threshold in eikonal-like schemes. Most importantly, our findings indicate that within the $U$-matrix scheme, an increase in exchanged pomerons results in more pronounced pomeron correlations and that this correlated resummation plays a key role in enhancing multi-parton collisions. We argue that the choice of unitarization scheme is not arbitrary, as it directly dictates the statistical structure of multi-reggeon exchanges. By reflecting the composite nature of hadrons, rational alternatives to eikonal-like schemes, such as the $U$-matrix, offer a compelling theoretical foundation for modeling high-energy hadronic collisions, provided that specific formulations can be identified that strictly satisfy all mathematical and physical constraints.

hep-ph↗
arXiv2026

Two-loop renormalisation of quark and gluon fields in the SMEFT

We compute the contributions of CP-conserving operators in the dimension-six SMEFT to the two-loop renormalisation constants of quark and gluon fields in the $\overline{\textrm{MS}}$-scheme. Specifically, we consider the top-quark chromomagnetic operator and the triple gluon operator. We work with the background-field method, which allows us to extract the contribution of these operators to the two-loop running of the top mass and the strong coupling constant. We discuss in detail the mixing with the unphysical operators required for the renormalisation, and we present analytic results for the renormalisation constants of all relevant operators.

hep-ph↗
arXiv2026

Two-loop renormalisation of quark and gluon fields in the SMEFT in the on-shell scheme

We compute the contributions of CP-conserving dimension-six SMEFT operators to the two-loop renormalisation constants of quark and gluon fields in the on-shell scheme. Specifically, we consider the top-quark chromomagnetic operator and the triple gluon operator. We also compute the contribution of four-quark operators to the gluon renormalisation constant and discuss the implications for the running of the strong coupling constant.

hep-ph↗