Kaonic atoms measurements at the DAΦNE collider: the SIDDHARTA-2 experiment

The X-ray spectroscopy measurements of light kaonic atoms’ deexcitation towards the fundamental level provide unique information on the low-energy Quantum ChromoDynamics (QCD) in the strangeness sector, being a direct probe of the kaon/nucleon interaction at threshold, unobtainable through the scattering experiments. In this framework, the SIDDHARTA-2 collaboration is going to perform the first kaonic deuterium 2p → 1s transition measurement at the DAΦNE collider of Istituto Nazionale di Fisica Nucleare – Laboratori Nazionali di Frascati. Combining this measurement with the kaonic hydrogen one performed by SIDDHARTA in 2009 it will be possible to obtain, in a model-independent way, the isospin-dependent antikaon-nucleon scattering lengths. The paper introduces the SIDDHARTA-2 setup, an upgraded version with respect to the one used for the kaonic hydrogen measurement, dedicated to the ambitious kaonic deuterium measurement, together with the preliminary results obtained during the kaonic helium run, preparatory for the SIDDHARTA-2 data taking campaign.

RELATIVISTIC THEORY OF SPECTRAL CHARACTERISTICS OF PIONIC ATOMIC SYSTEMS: APPLICATION TO HEAVY SYSTEMS

A new theoretical approach to energy and spectral parameters of the hadronic (pionic and kaonic) atoms in the excited states with precise accounting for the relativistic, radiation and nuclear effects is presented. There are presented data of calculation of the energy and spectral parameters for pionic atoms of the 93Nb, 173Yb, 181Ta , 197Au, with accounting for the radiation (vacuum polarization), nuclear (finite size of a nucleus ) and the strong pion-nuclear interaction corrections. The measured values of the Berkley, CERN and Virginia laboratories and alternative data based on other versions of the Klein-Gordon-Fock theories with taking into account for a finite size of the nucleus in the model uniformly charged sphere and the standard Uhling-Serber potential approach for account for the radiation corrections are listed too.

Kaonic Atoms to Investigate Global Symmetry Breaking

Kaonic atoms measure the antikaon-nucleus interaction at almost zero relative energy, allowing one to determine basic low-energy quantum chromodynamics (QCD) quantities, namely, the antikaon-nucleon ( K ¯ N) scattering lengths. The latter are important for extracting the sigma terms which are built on the symmetry breaking part of the Hamiltonian, thereby providing a measure of chiral and SU(3) symmetries breaking. After discussing the sigma terms and their relations to the kaonic atoms, we describe the most precise measurement in the literature of kaonic hydrogen, performed at LNF-INFN by the SIDDHARTA experiment. Kaonic deuterium is still to be measured, and two experiments are planned. The first, SIDDHARTA-2 at LNF-INFN was installed on DA Φ NE in spring 2019 and will collect data in 2020. The second, E57 at J-PARC, will become operative in 2021.