Precision Differential Analysis of the Rare Hyperon Decay Sigma to p mu mu in LHCb

Objective

This proposal, FOUNDRY, will establish a new production line for discovery in the strange sector. It aims to deliver the world's first measurements of the differential branching fraction and forward-backward asymmetry in the q2 distribution of Sigma to p mumu decays. Simultaneously, an essential tool facilitating future exploration will be created, the inaugural strange flavour-tagging algorithm at LHCb. This project directly addresses the primary obstacle in interpreting experimental data: the 8-fold model-dependent ambiguity in the dimuon mass spectra that obscures the absolute branching fraction. To achieve the systematic precision necessary to distinguish between degenerate solutions in data, we aim to meet the primary challenge of developing a state-of-the-art efficiency model in bins of q2. This will enable a precise efficiency correction of the raw signal yields, yielding a definitive test of Standard Model predictions in the strange-baryon sector. Utilizing the vastly increased Sigma+ dataset from LHCb's Run 3, these advanced methodologies are poised for a transformative measurement. Any observed deviation from Standard Model expectations could provide clear evidence of New Physics in s to p mumu transitions, a sector with a known history of anomalies. The host institution, the University of A Coruña, Spain, offers an optimal environment for this groundbreaking research, with proven expertise in rare-strange-decay analyses and strategic leadership as primary developers of LHCb's inclusive b-hadron flavour-tagging algorithm. This fellowship will be pivotal for the researcher's career, enabling knowledge transfer from high-statistics charm and beauty physics, expanding the host's programme into high-statistics strange decays, acquiring new skills in flavour tagging, and fostering international collaboration within the Spanish and Chinese research communities.