Jan 21 – 25, 2019
Bormio, Italy
Europe/Berlin timezone

In-medium properties of Λ in π− - Induced Reactions at 1.7 GeV/c

Jan 24, 2019, 6:40 PM
Bormio, Italy

Bormio, Italy

Short Contribution Thursday Afternoon Session


Mr Steffen Maurus (TUM)


The high precision measurement of a two solar mass neutron star, gives a strong constrain to the equation of state (EOS) of several models describing such dense objects. While more data and recent experimental observations reduce the allowed phase space, the appearance of hyperons inside the neutron star core is still a discussed scenario. For all these EOS the interaction of the hyperon with (normal) nuclear matter is the key ingredient. Of particular interest is thus the $\Lambda$ hyperon, which should appear first, as it is the lightest hyperon. The Lambda-p interaction is known to certain extend and the existence of hypernuclei demonstrates the attractive nature of the lambda-nucleus interaction, no differential study of the Lambda propagation within nuclear matter was carried out so far. In 2014 the HADES collaboration measured $\pi^- + A$ ( A = C, W) reactions at an incident pion momentum of 1.7 GeV/c. Since the pion-nucleon cross section is rather larger, the hyperon production occurs at the surface of the nuclei for pion induced reactions . This provides an ideal system, as the path length of the produced hyperons through nuclear matter is rather large and hence in-medium properties can be studied. In our experimental approach we are selecting the exclusive channel of $\pi^-+p \rightarrow \Lambda + K^0$ reconstructed in term of their associated dominant charged decay products in an light (C) and heavy (W) nuclear environment. With the help of the GiBUU transport code, we are able to test different scenarios, which include different couplings of the $\Lambda$ to normal nuclear environment in combination with the $K^0$. One of this scenario also includes for the first time an repulsive $\Sigma^0$ potential, predicted by $\chi$-effective theory. We will report on the on-going analysis and present our sensitivity on the different scenarios of the in-medium propagation.

Primary author


Prof. laura fabbietti (Technische Universitaet Muenchen)

Presentation materials