Cold and stable antimatter for fundamental physics

Abstract

The field of cold antimatter physics has rapidly developed in the last 20 years, overlapping with the period of the Antiproton Decelerator (AD) at CERN. The central subjects are CPT symmetry tests and Weak Equivalence Principle (WEP) tests. Various groundbreaking techniques have been developed and are still in progress such as to cool antiprotons and positrons down to extremely low temperature, to manipulate antihydrogen atoms, to construct extremely high-precision Penning traps, etc. The precisions of the antiproton and proton magnetic moments have improved by six orders of magnitude, and also laser spectroscopy of antihydrogen has been realized and reached a relative precision of 2 × 10 −12 during the AD time. Antiprotonic helium laser spectroscopy, which started during the Low Energy Antiproton Ring (LEAR) time, has reached a relative precision of 8 × 10 −10 . Three collaborations joined the WEP tests inventing various unique approaches. An additional new post-decelerator, Extra Low ENergy Antiproton ring (ELENA), has been constructed and will be ready in 2021, which will provide 10–100 times more cold antiprotons to each experiment. A new era of the cold antimatter physics will emerge soon including the transport of antiprotons to other facilities.

Analysis of the timing of freely falling antihydrogen

“…The asymmetry between matter and antimatter observed in the Universe is one of the fundamental problems of modern physics challenging the Standard Model [1]. Hints on this puzzle are looked for in experiments testing CPT symmetry between matter and antimatter as well as the interaction of antimatter with gravity [2,3,4]. CPT tests are quite precise [5,6] but tests on antimatter gravity have currently a limited precision, with the sign of gravity acceleration not yet known experimentally [7].…”

Analysis of the timing of freely falling antihydrogen

“…The asymmetry between matter and antimatter observed in the Universe is one of the fundamental problems of modern physics challenging the Standard Model [1]. Hints on this puzzle are looked for in experiments testing CPT symmetry between matter and antimatter as well as the interaction of antimatter with gravity [2][3][4]. CPT tests are quite precise [5,6] but tests on antimatter gravity have currently a limited precision, with the sign of gravity acceleration not yet known experimentally [7].…”

Quantum interference measurement of the free fall of anti-hydrogen

“…One of the most important questions of fundamental physics is the asymmetry between matter and antimatter observed in the Universe [1][2][3][4]. In this context, it is extremely important to compare the gravitational properties of antimatter with those of matter [5][6][7][8][9][10][11].…”