Spin transparency as a new approach to precision tests of fundamental symmetries in polarization experiments at colliders and storage rings: theory and experiment

• Applicant: Professor Dr. Achim Stahl
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: from 2021 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 465236767

The search for new physics beyond the Standard Model is at the forefront of particle physics. Precision experiments on the spin of particles form a promising path to a major discovery. Experiments are in preparation to search for electric dipole moments of protons and deuterons. Such a dipole moment would demonstrate the violation of the CP- and T-symmetries and would shed light on the anomalously large baryon asymmetry of the universe. Axion-like particles, an interesting candidate for the unexplained dark matter in the universe, would introduce oscillating dipole moments, which could be detected in spin experiments. In the same category is the search for the semi-strong CP- and T-violation in hadronic interactions, where one looks for T-violating effects at the part-per-million level. Another domain of precision spin experiments is the long-standing spin-crisis of the nucleons, where the hitherto poorly known tensor structure function of deuterons is moving into focus.All aforementioned projects require stringent control of the spin orientation in storage rings, flexibility in the orientation of the spins, and long spin coherence times. With our project SpinTra we will develop a new method to control the spin in a storage ring and to align it in any desired direction. This method was proposed by Yury Filatov and collaborators. He is also the Russian PI of the project. We will work out the theoretical foundations, verify the concept with numerical simulations, built the required hardware, install it in the COSY ring at FZ Jülich, and demonstrate the feasibility with a proof-of-principle experiment.If successful, the method can be applied to enhance the science potential of the electron-Ion Collider eIC at the Brookhaven Laboratory in the US, Nuclotron-based Ion Collider fAcility NICA in Russia, the Electron-ion collider in China (EicC), or the semi-electric and all-electric storage rings for the search for electric dipole moments.The transnational collaboration between the Russian groups at MIPT and the German groups at RWTH Aachen University and the Forschungszentrum Jülich is essential for the success of the projects. The MIPT groups contribute their expertise on the theory aspects and they will built the hardware for the proof-of-principal. The German groups provide the COSY facility, a unique facility for such an experiment, and their experience in the conduction of high-precision spin experiments.

• DFG Programme: Research Grants
• International Connection: Russia
• Partner Organisation: Russian Science Foundation, until 3/2022
• Cooperation Partner: Dr. Yuri Filatov, until 3/2022
• Co-Investigator: Privatdozent Dr. Frank Rathmann