Coordinatori
Symmetries and Fundamental Interactions
- Luca Girlanda (Istituto Nazionale di Fisica Nucleare)
Three significant anomalies have been observed in the emission of electron-positron pairs in the $^{7}$Li(p,e$^+$e$^−$)$^{8}$Be, $^{3}$H(p,e$^+$e$^−$)$^{4}$He and $^{11}$B(p,e$^+$e$^−$)$^{12}$C nuclear reactions [1–3] that have been interpreted as the signature of a boson (referred to as X17) of mass M$_{X17}$ $\simeq$ 17 MeV/c$^2$ that could be the mediator of a fifth force, characterised by...
The Antimatter Factory at CERN, comprising the AD and ELENA particle decelerators, is a unique facility for experimental research with low-energy antiprotons. During its 20 years of activity, its main goal has been to allow forming (in combination with cold positrons plasma techniques) and studying cold antihydrogen atoms, as well as to deepen the investigations started at LEAR of the...
The goal of the FAMU experiment is the measurement of the hyperfine splitting of the mounic hydrogen ground state. This measurement gives an accurate insight of the proton's magnetic structure, plays a key role in veryfing the most accurate QED calculations and tests the interaction between proton and muon. The hyperfine splitting transition is detected by exciting muonic hydrogen using a...
The low-energy QCD, the theory within the Standard Model describing the strong interaction, is still missing fundamental experimental results in order to achieve a breakthrough in its understanding. Among these experimental results, the low-energy kaon-nucleon/nuclei interaction studies are playing a key-role, with important consequences going from particle and nuclear physics to astrophysics...
Starting from a complete set of relativistic nucleon-nucleon contact operators preserving parity and time reversal symmetries up to order $O(p^4)$ of the expansion in soft momenta $p$, we show that non-relativistic expansions of relativistic operators involve twenty-six independent combinations: two starting at $O(p^0)$, seven at order $O(p^2)$ and seventeen at order $O(p^4)$. This...
