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Dr Giuseppe Ruggiero

Formerly at Lancaster University


The Standard Model of particle physics has been phenomenally successful in describing interactions at high energy, as witness the LHC experiments at CERN and, in the past, the Tevatron experiments at Fermilab, the B-Factories at SLAC and KEK and the LEP experiments at CERN, and yet it offers no explanation for dark matter or dark energy. The mainstream approach within particle physics is to extend the energy frontier and to search for direct evidence of new particles being produced. The complementary approach is to study with very high precision those processes predicted to occur extremely rarely within the Standard Model, because it is here that hints of new physics may manifest themselves. A key requirement in this study is that the predictions from the SM be precise and robust. 

My current interest is to study rare-decay processes with high precision and in particular to measure the decay branching ratio (BR) of K+ → π+ νν decay. The Standard Model precisely predicts a BR for this decay of about 10-10, such to offer a (model-dependent) potential mass-reach of 100 TeV for the discovery of new particles. Even considering the present constraints on new physics from LHC, already a 10% precision measurement of the K+ → π+ νν BR could provide a potential discovery of physics beyond the SM, offering also the possibility to study effects in flavour physics complementary to those investigated by the LHC experiments with B mesons. To this extent a dedicated fixed target experiment, NA62, is running at CERN, using protons extracted from the SPS accelerator, the main injector of LHC. NA62 has already collected about 3×1012 kaon decays in 2016 and 2017, with the goal to reach about 1013 decays by the end of 2018. Therefore the measurement the K+ → π+ νν BR requires sophisticated analysis technique to handle a huge amount of data and to suppress the background of 12 order of magnitude, while keeping enough signal to reach the required 10% precision. I’m currently Physics Coordinator of NA62 and responsible of the data analysis.

In past years I have been one of the main designer of the NA62 experiment of which I’ve written the full reconstruction of the tracking system and studied the physics sensitivity prior to the construction. I’ve been also member of the NA48 experiment at CERN and I contributed to the study of possible deviation from lepton universality in the charged kaon system and to the study of the matter antimatter asymmetry (CP-violation) both in the system of charged and neutral kaon mesons.

  • Published

    Measurement of the K+ → π+γγ decay

    The NA62 Collaboration, 31/03/2024, In: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. 850, p. 138513 1 p., 138513.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  • Published

    First observation and study of the K±→ π0π0μ±ν decay

    The NA48/2 Collaboration, 22/03/2024, In: Journal of High Energy Physics. 2024, 3, 137.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  • Published

    Search for K+ decays into the π+e+e−e+e− final state

    NA 62 Collaboration, 10/11/2023, In: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. 846, 138193.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

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