17-22 July 2016
Master Cutlers Hall
Europe/London timezone

Search for heavy neutral leptons with the near detector complex ND280 of the T2K neutrino experiment at J-PARC

18 Jul 2016, 14:40
Venue: Cutlers' Banqueting Hall (First Floor); Chair: Gabriella Sciolla; Session Manager: Frederic Mouton ()

Venue: Cutlers' Banqueting Hall (First Floor); Chair: Gabriella Sciolla; Session Manager: Frederic Mouton


Dr. Alexander Izmaylov (IFIC CSIC)


T2K (Tokai-to-Kamioka) is a second-generation long-baseline accelerator experiment that studies neutrino oscillations using an intense beam of muon neutrinos produced by the the 30 GeV proton synchrotron at J-PARC. The near detector complex ND280 consists of different sub-detectors, including time-projection chambers (TPCs), scintillator tracking detectors and calorimeters, operated inside a magnetic field. The detector thus provides unique tracking capabilities to identify various outgoing products. Hence the presence of the intense neutrino beam from mainly π/K parents combined with ND280 tracking apparatus opens up the possibility to study not only neutrino interactions but to search for "new physics" as well. This talk is focused on the search for the so-called Heavy Neutral Leptons (HNLs, heavy neutrinos) by means of the T2K ND280. HNLs with masses below the electroweak scale are considered in some extensions of the Standard Model (e.g. νMSM) in order to address the present open questions: neutrino oscillations and masses, dark matter and the baryon asymmetry of the Universe. In the mass range of < 500 MeV/c2 these heavy neutrinos can be produced in pion or kaon decays, and further decay themselves into charged particles, hence allowing for their detection in a detector media. Probing the kaon parents` decays allows one to study a wider mass range of heavy neutrinos. By using the TPC volumes (filled with argon gas) to search for heavy neutrino events it is possible to significantly reduce the backgrounds coming from interactions of active neutrinos. A detailed simulation of the HNL flux was performed for the T2K ND280 layout and the detector performance was studied with respect to the reconstruction of heavy neutrino vertices. It is shown that with the current ND280 dataset (~1x1021 POT) one can obtain bounds on the HNL mixing parameters comparable to those of the CERN PS191 experiment, which, together with the BNL E949 data, put the most stringent constrains on HNLs with masses in the range 140 MeV/c2 < mHNL< 450 MeV/c2. Furthermore the T2K ND280 data can be used to improve the current experimental limits in the mass region close to the kaon mass. In addition the talk will also briefly review the T2K potential for searching for other possible "new physics" signals.

Primary author

Dr. Alexander Izmaylov (IFIC CSIC)

Presentation Materials

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