The LHCb group of the Centre de Physique des Particules de Marseille (CPPM) and Aix-Marseille University (AMU) invites applications for a 3-year postdoctoral researcher position to search for physics beyond the Standard Model in semileptonic B meson decays at LHCb and to enhance LHCb's heterogeneous real-time selection software for future upgrades.

The LHCb experiment at the LHC proton-proton collider at CERN is dedicated to studies of heavy flavour physics, with the major goal to find deviations from the Standard Model of particle physics in decays of heavy hadrons. After a major upgrade, LHCb restarted data taking in 2022 with Run 3 of the LHC. The unprecedented data sample to be collected until 2025 will be the basis of the analysis.

Over the last years, deviations from LFU have appeared in b-hadron decays, such as in the ratios of branching fractions in b → clν transitions. Though no single measurement constitutes an observation, together they point to a pattern of effects beyond the Standard Model (SM). You will play a leading role in characterizing the angular decay distributions of B → D* l ν decays with electrons in the final state, which are sensitive to New Physics.
To this end, you will study the multidimensional distributions of the kinematic parameters that characterise the internal degrees of freedom of semileptonic multibody decays. You will employ a multidimentional fit, modeling background processes with templates and including detector resolution effects.

The measurement is enabled by LHCb's new real-time selection system fully implemented in software. It uses graphics processing units (GPUs) for the first reconstruction and inclusive selection stage and CPU servers for a refined reconstruction and exclusive selections. In preparation of LHCb's next Upgrade, where a data rate five times larger than in Run 3 will have to be processed, the existing framework needs to be enhanced to allow also the second selection stage to be processed on GPUs. You will be an active player in qualifying the heterogeneous system for the next upgrade. This will require the usage of modern computing techniques, such as programming for GPU architecture and developments within a heterogeneous software framework.

Situated at the heart of the "Callanques National Park", on Luminy campus, CPPM is a joint research laboratory between CNRS and Aix-Marseille University with a staff of around 180 researchers, engineers and PhD students. The laboratory studies topics ranging from particle physics, astroparticle physics and cosmology, with a strong technological force in electronics, mechanics, instrumentation and IT, enabling the design and construction of state-of-the-art detector systems, often required to operate under extreme conditions: deep under the sea, in space or underground. Most of our research is carried out within leading international scientific collaborations and our contributions are recognized worldwide. CPPM is committed to ethical reserach and to diversity and inclusion in the workplace, and provides administrative and logistics support for newcomers. (more details here: https://www.cppm.in2p3.fr/web/en/index.html)
The LHCb group at CPPM is actively involved in studies of semileptonic and rare B decays, and leads major projects in the development of the data acquisition system.

The position is for three years, funded by the ERC grant “Accelerated Precision Tests of Lepton Universality” (ALPaCA). As successful candidate you will travel to CERN regularly to participate in LHCb's data-taking and attend national and international workshops and conferences.