arXiv subjects

Stefan Meiser

Publications and source records attributed to Stefan Meiser.

3 recordsLinked to original sources

arXiv2026

Inclusive Charmless Non-Leptonic B Decays at NLO within and beyond the Standard Model

We calculate the full set of BSM contributions to the inclusive non-leptonic $B$-meson lifetime from charmless final states within the framework of the Weak Effective Theory up to next-to-leading order in QCD and to leading power in the heavy-quark expansion. We do so by computing cut diagrams and the corresponding phase space integrals. This involves calculating current-current, penguin-penguin, penguin-dipole and dipole-dipole diagrams with two-, three- and four-particle cuts. We describe the technical difficulties of the computation. We then discuss how our results can be used to constrain new physics scenarios related to the anomalies observed in semi-leptonic and charmless non-leptonic decays.

hep-ph↗

arXiv2024

Towards a Global Analysis of the $b\to c\bar{u} q$ Puzzle

We study the nonleptonic decays $\bar{B}_s^0 \to D_s^{(*)+} \pi^-$ and $\bar{B}^0 \to D^{(*)+} K^-$ within the Weak Effective Theory (WET) up to mass-dimension six. We revisit the calculation of the hadronic matrix elements within QCD Factorization including the full set of WET operators. We recalculate the two-particle contributions to the hard-scattering kernels at next-to-leading order in $\alpha_s$, confirming recent results in the literature. We also calculate the three-particle contributions at leading order in $\alpha_s$, clarifying the procedure, refining the SM results in the literature, and providing for the first time the complete set of contributions within the WET. We use these results to perform a global phenomenological study of the effective couplings, putting bounds on the size of the WET Wilson coefficients in four distinct fit models. The fits include constraints from the nonleptonic $B$-meson decay width, which we calculate at the leading order for the full set of WET operators for the first time. This study is the first one to account for simultaneous variation of up to six effective couplings. We identify two distinct modes in all fit models and discuss how future measurements can be used to distinguish between them.

hep-ph↗

arXiv2021

EOS -- A Software for Flavor Physics Phenomenology

EOS is an open-source software for a variety of computational tasks in flavor physics. Its use cases include theory predictions within and beyond the Standard Model of particle physics, Bayesian inference of theory parameters from experimental and theoretical likelihoods, and simulation of pseudo events for a number of signal processes. EOS ensures high-performance computations through a C++ back-end and ease of usability through a Python front-end. To achieve this flexibility, EOS enables the user to select from a variety of implementations of the relevant decay processes and hadronic matrix elements at run time. In this article, we describe the general structure of the software framework and provide basic examples. Further details and in-depth interactive examples are provided as part of the EOS online documentation.

hep-ph↗