Bonn 2020 – wissenschaftliches Programm
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HK 13.3: Vortrag
Dienstag, 31. März 2020, 17:45–18:00, J-HS A
Observation of the hypertriton in pp collisions with ALICE at the LHC — •Michael Hartung — Institut für Kernphysik, Goethe-Universität, Frankfurt, Germany
The hypertriton lifetime represents one of the open key questions of hypernuclear physics. The separation energy of the Λ inside the hypertriton is only 130 keV and this implies a small modification of the Λ wave function inside the nucleus, hence the lifetime of the hypertriton is expected to be close to that of the free Λ. The average value of the results obtained with different experimental techniques was found to be significantly lower than the theoretical prediction and this disagreement is referred to as the hypertriton lifetime puzzle. Significant hypertriton yields have only been measured in Pb-Pb collisions at the LHC. Due to its weak decay, the hypertriton can be reconstructed from its daughter products, e.g. the charged two-body decay channel Λ3H →3He + π−. In order to be able to measure these rare (anti-) nuclei also in pp collisions, it is essential to increase the statistics by employing a dedicated trigger on nuclei. The Transition Radiation Detector of ALICE offers unique trigger capabilities. In combination with the excellent particle identification through the energy-loss measurement in the Time Projection Chamber and the capabilities to separate primary particles from those from secondary decays, provided by the Inner Tracking System, it is possible to identify the hypertriton in pp collisions. In this talk, the first observation of the hypertriton in pp collisions is presented as well as the current status of the lifetime measurement. Supported by BMBF and the Helmholtz Association.