Periodic Reporting for period 3 - SELDOM (Search for the electric dipole moment of strange and charm baryons at LHC) Reporting period: 2020-05-01 to 2021-10-31 Summary of the context and overall objectives of the project SELDOM explores a new experimental method to decisively boost the study of the electric dipole moment (EDM) and magnetic dipole moment (MDM) of baryons at the LHCb experiment at CERN.SELDOM will be a crucial piece in the puzzle to explain the absence of antimatter in the Universe, and it has the potential to shorten the path to new physics discoveries opening up new research opportunities.The ultimate goals of SELDOM are: i) first search for charm baryon EDM; ii) search for the Λ baryon EDM with improved sensitivity with respect to the current limit.SELDOM would contribute to the search of new physics through the search of the EDM of unstable particles, and also to the understanding of the mechanism of baryogenesis. Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far In the framework of the SELDOM project significant achievements have been reached so far. 1) Work Package 1: event reconstruction developed new tracking and trigger algorithms for long-lived Λ baryons using simulated events;improved tracking algorithm for scintillating fibre tracker at LHCb, relevant for long-lived Λ baryons decaying after the magnet; demonstrated the feasibility of the reconstruction of long-lived Λ baryons decaying after the magnet using LHCb Run2 data;optimised reconstruction of Λc+→pK−π+ and Xic+→pK−π+ charm baryon decays in p-gas collisions at LHCb;simulation studies of fixed-target setup and detector performance studies for the reconstruction of charm baryon decays; 2) Work Package 2: data analysis measurement of the polarisation of baryons from charm baryon decays in progress; performed an amplitude analysis and polarisation measurement of Λc+→pK−π+ decays in pp collisions. Amplitude analysis and polarisation measurement of Xic+→pK−π+ decays in pp collisions in progress;analysis for determining the polarisation of Λc+ baryons produced in p-Ne fixed-target collisions in progress; 3) Work Package 3: fixed-target setup design and simulation studies of fixed-target collisions; developed an improved experimental setup and advanced experimental techniques for optimal sensitivity to charm baryon dipole moments;construction of long bent crystals (8 cm long, 16 mrad bending angle) and successful test on beam at the CERN SPS. The latter represents a major achievement of the project.development of an innovative anodic bonding technique for improved precision bent crystal construction. Silicon crystal prototypes bonded on a glass substrate with preformed bent shape with sub-micron precision; project being reviewed at CERN and included in the Physics Beyond Collider report presented to the European Strategy for Particle Physics; design of crystal goniometer and study for system integration in the experiment;vi) design and simulation studies for an experimental test in LHC of the fixed-target setup. vii) a new method for the measurement of the tau lepton dipole moments was conceived and published in a journal article, Phys. Rev. Lett. 123, 011801 (2019). Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far) The project is expected to produce significant progress beyond the state of art:i) development of a new generation of long-bent crystals for channeling and spin precession of TeV particles;ii) realisation of a new fixed-target experiment at the LHC;iii) improved understanding of the dynamics of charm baryon decays with amplitude analyses;iv) first cross-section and polarisation measurements of charm baryons produced in fixed-target collisions at the LHC;v) first MDM measurements for charm baryons;vi) development of new tracking and trigger algorithms for the reconstruction of long-lived particles at LHCb;vii) new branching ratio and polarisation measurements of Λ baryons from weak charm decays; viii) measurement of the Λ and anti-Λ baryon MDM for a test of the CPT symmetry. Logo SELDOM essential JPG Logo SELDOM PNG Logo SELDOM essential PNG Logo SELDOM JPG
