6533b830fe1ef96bd129707a
RESEARCH PRODUCT
Measurement of the proton scalar polarizabilities at MAMI
Edoardo Mornacchisubject
Particle physicsPhoton530 PhysicsQC1-999media_common.quotation_subject01 natural sciencesAsymmetryNuclear physicsPion0103 physical sciences500 Natural sciences and mathematicsNuclear Experiment010306 general physicsmedia_commonPhysics010308 nuclear & particles physicsLinear polarizationPhysicsCompton scatteringScalar (physics)Particle Data Group530 PhysikMagnetic field500 NaturwissenschaftenNucleonCrystal Balldescription
The electric (αE1) and magnetic (βM1) scalar polarizabilities describe the response of the nucleon to an applied electric or magnetic field. They are not only fundamental properties related to the internal structure and dynamics of the nucleon, but they are important also in other areas of physics, such as atomic structure. The values of αE1 and βM1 quoted by the Particle Data Group were determined using data on the unpolarized differential cross-section of the Compton scattering $\gamma p \to \gamma p$. The measurement of the beam asymmetry Σ3, provides an alternative approach to the extraction of the scalar polarizabilities, with different sensitivity and systematics compared to the unpolarized crosssection. This asymmetry was measured recently for the first time below the pion photoproduction threshold by the A2 Collaboration with the Crystal Ball/TAPS experiment at MAMI (Mainz, Germany). A new high precision measurement of both a unpolarized cross-section and beam asymmetry Σ3a is ongoing at MAMI and the polarizabilities αE1 and βM1 will be extracted with unprecedented precision.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2019-01-01 | Proceedings of XVII International Conference on Hadron Spectroscopy and Structure — PoS(Hadron2017) |