Strong interaction studies with kaonic atoms

J Márton ,M Bazzi,P Levi Sandri,F Ghio,E Sbardella,M Iwasaki,K Piscicchia,H Tatsuno,T Ishiwatari,T Ponta,D Pietreanu,M Iliescu,R Quaglia,C Guaraldo,G Beer,A Scordo,R Hayano,M Cargnelli,A Clozza,D Bosnar,E Widmann,A Romero Vidal,D Sirghi ,C Curceanu,C Fiorini,J Zmeskal,C Berucci,F Sirghi,A M Bragadireanu ,H Shi,A D’Uffizi,O Vázquez Doce ,S Okada

doi:10.1051/epjconf/201611303009

Abstract

The strong interaction of antikaons with nucleons and nuclei in the low-energy regime represents an active research field connected intrinsically with few-body physics. There are important open questions like the question of antikaon nuclear bound states. A unique and rather direct experimental access to the antikaon-nucleon scattering lengths is provided by precision X-ray spectroscopy of transitions in low-lying states of light kaonic atoms like kaonic hydrogen isotopes. In the SIDDHARTA experiment at the electron-positron collider DAFNE of LNF-INFN we measured the most precise values of the strong interaction observables, i.e. the strong interaction on the 1s ground state of the electromagnetically bound kaonic hydrogen atom leading to a hadronic shift and a hadronic broadening of the 1s state. The SIDDHARTA result triggered new theoretical work which achieved major progress in the understanding of the low-energy strong interaction with strangeness. Antikaon-nucleon scattering lengths have been calculated constrained by the SIDDHARTA data on kaonic hydrogen. For the extraction of the isospin-dependent scattering lengths a measurement of the hadronic shift and width of kaonic deuterium is necessary. Therefore, new X-ray studies with the focus on kaonic deuterium are in preparation (SIDDHARTA2). Many improvements in the experimental setup will allow to measure kaonic deuterium which is challenging due to the anticipated low X-ray yield. Especially important are the data on the X-ray yields of kaonic deuterium extracted from a exploratory experiment within SIDDHARTA.

Highlights

Hadronic atoms like pionic and kaonic atoms are extremely valuable systems for the investigation of the strong interaction in the low-energy domain.Especially interesting is the strong interaction involving the strange quark which plays a peculiar role
In the SIDDHARTA experiment at the electron-positron collider DAΦNE of LNF-INFN we measured the most precise values of the strong interaction observables, i.e. the strong interaction on the 1s ground state of the electromagnetically bound K−p atom leading to a hadronic shift 1s and a hadronic broadening Γ1s of the 1s state
New X-ray studies with the focus on kaonic deuterium are in preparation (SIDDHARTA2)

Summary

Introduction

Hadronic atoms like pionic and kaonic atoms are extremely valuable systems for the investigation of the strong interaction in the low-energy domain. The most basic exotic atom with strangeness represents kaonic hydrogen (K−p) which is an electromagnetically bound exotic atom consisting of a proton and an antikaon (K−). In this system one can study the explicit and spontaneous chiral symmetry breaking in a fairly direct way by spectroscopy of x-rays emitted in the transitions to the 1s ground state, in this way the threshold data can be deduced. In order to deduce the experimental values of isospin-separated antikaon-nucleon scattering lengths one needs the hadronic shift 1s and width Γ1s in kaonic hydrogen and kaonic deuterium which can be extracted from the X-ray transitions to the 1s ground state in both kaonic systems

Kaonic hydrogen

Kaonic deuterium

Summary and Outlook