Speaker
Dr
Matteo Fael
(University of Siegen)
Description
The heavy mass expansion (HME) has been an indispensable tool for precision calculation in flavor physics, especially for bottom hadrons. However, there have been always doubt if the HME is applicable to charm decays with the same success since both $\alpha_s(m_c)$ and $\Lambda_\mathrm{QCD}/m_c$ are not very small parameters.
However one can turn the vice into a virtue. Since $\Lambda_\mathrm{QCD}/m_c$ is not that small, there is a larger sensitivity to higher order terms of the HME in charm decays compared to bottom decays. To this end, inclusive semileptonic charm decays may serve as a tool to study the anatomy of the subleading terms of the HME.
In this talk I will report about some recent developments in the evaluation of the $\Lambda_\mathrm{QCD}^3/m_c^3$ and $\Lambda_\mathrm{QCD}^4/m_c^4$ terms for semileptonic charm decays. For the charm, the appropriate expansion is a double seires in powers of $m_s/m_c$ as well as in $\Lambda_\mathrm{QCD}/m_c$. The expansion is not just a trivial tailor series of the results for the $b\to c$ transition but it contains also non analytic terms due to the infrared sensitivity to the strange mass emerging at higher order.
Primary author
Dr
Matteo Fael
(University of Siegen)
