| Laboratoire : | Centre de Physique des Particules de Marseille Case 902 |
| 163 avenue de Luminy - 13288 Marseille Cedex 9 | |
| Directeur : | Cristinel Diaconu - 04.91.82.72.01 - diaconu@cppm.in2p3.fr |
| Correspondant : | William Gillard - 04.91.82.72.67 - gillard@cppm.in2p3.fr |
| Groupe d'accueil : | Belle II |
| Chef de groupe : | Justine Serrano - 04.91.82.72.80 - serrano@cppm.in2p3.fr |
| Directeur de thèse : | Vitalii Lisovskyi - lisovskyi@cppm.in2p3.fr |
Thématique : Physique des particules
Decays of heavy-quark hadrons provide a powerful indirect probe of beyond-the-Standard-Model effects, by comparing the measured decay properties to their theoretical predictions. Although our Universe is composed of baryons, our knowledge of heavy-quark baryon properties remains very limited.
The baryons that contain a charm quark have been studied for more than 40 years, but there still exist significant gaps in our knowledge of their properties and decays. This is a limitation for any searches for physics beyond the Standard Model involving charm-baryon decays, or beauty hadron decays into charm baryons. In particular, baryonic decays contribute to several percents of the B-meson decay width, but are poorly known to date.
The Belle II detector at KEK (Japan) is aimed at precision measurements of properties of beauty and charm hadrons, as well as tau leptons (https://inspirehep.net/literature/1692393). The Belle II collaboration consists of more than 1000 scientists and is collecting data since 2019. The key feature of the Belle II detector is the nearly 4pi angular acceptance, which allows to perform the full reconstruction of the visible collision products and calculation of the missing energy.
At Belle II, charm baryons can be produced either promptly in the e+e->ccbar process, or from decays of B mesons.
Combined with conservation laws in these processes, this allows to fully reconstruct a subset of collision products and deduce the properties of the remaining ones. In the scope of this PhD thesis, the powerful algorithms for full event interpretation and B-meson tagging (https://arxiv.org/abs/1807.08680), will be extended to include charm baryons. In addition, production of charm baryons in B-meson decays will be studied.
?A better understanding of baryonic B-meson decays will in particular help to improve the performance of B-tagging at Belle II. The impact of enhancing B-tagging efficiency will directly boost sensitivity in all analyses reliant on this technique.
The developed tagging techniques can also be extended to charm- and B-tagging at the planned experiments at FCCee, enabling the broad flavour physics programme for the decades to come.
Activities:
Data analysis using Machine Learning techniques, participation to data taking, participation to Belle II service tasks, activities of outreach and dissemination.
Work context:
The successful candidate will be based at CPPM, Marseille (https://www.cppm.in2p3.fr).
Travel to KEK (Japan) for participation to the Belle II data taking and collaboration meetings is foreseen.
The student will work closely with the team funded by the ANR project StrangeCharm.
Additional information:
Applicants must hold a Master degree (or equivalent) in Physics, or expect to hold such a degree by the start of employment. Application must include a CV, grade records, and a motivation statement. Please also provide the names of two contact persons who can send letters of recommendations if requested.
Prior knowledge of ROOT, C++ or python, is an advantage, but not mandatory.
This thesis is expected to start in October 2025 (if funding is obtained).
Additional references:
https://arxiv.org/abs/1312.7826
https://arxiv.org/abs/1811.09738
https://arxiv.org/abs/1904.12093
https://arxiv.org/abs/1807.08680