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Portail > Offres > Offre UMR7346-ANNPOR-084 - CDD Chercheur(e) dans l'expérience LHCb au CPPM - Marseille - H/F

Postdoc position with the LHCb experiment at CPPM (Marseille)- M/F

This offer is available in the following languages:
Français - Anglais

Date Limite Candidature : mardi 5 juillet 2022

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General information

Reference : UMR7346-ANNPOR-084
Workplace : MARSEILLE 09
Date of publication : Tuesday, June 14, 2022
Type of Contract : FTC Scientist
Contract Period : 24 months
Expected date of employment : 1 September 2022
Proportion of work : Full time
Remuneration : Between 2743 euros and 3893 euros gross per month according to experience
Desired level of education : PhD
Experience required : 1 to 4 years


The LHCb group of the Centre de Physique des Particules de Marseille (CPPM) invites applications for a 2-years postdoc position on searching for physics beyond the Standard Model in semileptonic B meson decays and on improving LHCb's new real-time selection software. The LHCb experiment at the LHC proton-proton collider at CERN is dedicated to the searches for Physics Beyond the Standard Model (BSM) studying beauty and charm hadrons. After a major upgrade, LHCb will restart data taking in 2022. Over the next years, it will collect unprecedented data samples bringing the measurements to a new level of precision. In the past 10 years, two intriguing anomalies have shown up in the flavour sector. One related to the b→sll flavour changing neutral current and another one in the b→cτν charged current. Both effects are ~ 3-4σ away from the Standard Model (SM) expectation.

Concerning the second effect, the measured quantities are the ratios of branching fractions R(D(*))=BR(B→D(*)τν)/BR(B→D(*)lν) (l=μ,e) . In the Standard Model, the only difference between the numerator and the denominator is the lepton mass. When combining the results of the BaBar, Belle and LHCb experiments, the measurements appear to be 3.4σ away from their SM expectation. This is a striking hint of violation of the lepton flavour universality which clearly needs to be checked by all means.

As successful candidate, you will play an active role in analyzing the charged anomalies, studying decays of B→D(*)τν.


As a successful candidate, you will study the B→D(*)τν channel, where the τ lepton is reconstructed into its 3 pions final state (π+π−π+ν) . In addition to a measurement of the branching ratio and R(D*), you will perform an angular analysis of the decay products which will bring new sensitivity to BSM effects. You will use the full run1 and run2 data sets (2011-2018) and develop the tools to study the new collision data starting in 2022 (run3). This will allow to achieve an unprecedented precision and hopefully clarify the current situation.

In addition to your activities in physics analysis, you will contribute to the LHCb Real-Time Analysis (RTA) project. You will take part in the development of the software infrastructure for automated particle identification calibration for the upgraded LHCb detector based on high-statistics calibration data samples. You often travel to Cern, to participate to run3 data taking, and to present you results.


Applicants must hold, or are about to obtain, a PhD in particle physics. Excellent knowledge of particle physics, mathematical methods of data analysis, and modern software development skills (python, C++, gitlab CI/CD) are required.

Work Context

At CPPM, around 180 researchers, engineers and PhD students study topics ranging from particle physics, astroparticle physics, cosmology to dark matter. The LHCb group at CPPM consists of seven permanent researchers, four engineers, one postdoctoral researcher and two PhD students. The group is deeply involved in the LHCb experiment since its beginning in 1997. We have been actively involved in studies of semileptonic and rare B decays, as well as in the development of the new data acquisition system being installed now at CERN.

The position is funded by the “Fellowships of the two infinities” of the national particle physics institute in France (IN2P3) for two years.

Constraints and risks

Possible international travel for missions.

Additional Information

Applications should include a statement of interest (1 page) and CV (max 2 pages), as well as three reference letters, to be sent to the contacts below.

The position is opened until filled, with a deadline for application on May 31st 2022. The starting of your contract can be between June and December 2022. For more information, please contact Olivier Leroy (Olivier.Leroy@in2p3.fr) and Anton Poluektov (Anton.Poluektov@cern.ch)


- Measurement of B→D*τν branching fraction using three-prong τ decays, Phys. Rev. D97, 072013 (2018), https://arxiv.org/abs/1711.02505

- Model-independent method for measuring the angular coefficients of B→D*τν decays, JHEP 11 (2019) 133, https://arxiv.org/abs/1908.04643

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