- ALPHA experiment observed one of the spectral lines of antihydrogen for the first time. The measurement was done by observing the 1S-2S transition. CPT symmetry demands that the spectra of hydrogen and antihydrogen be identical. The experiment confirmed that the 1S-2S spectral line of antihydrogen is exactly the same as 1S-2S line of hydrogen. This is a confirmation of the CPT symmetry.
- There is an excellent presentation by Joel Fajans that explains spectroscopy of antihydrogen atoms and many other aspects of the ALPHA experiment. I highly recommend this very readable tutorial which has lots of pictures and diagrams.
- Protons are the most stable composite particles in the universe. Protons do not decay. Protons can be broken as in LHC experiments at CERN but they do not decay by themselves. Latest experimental lower limit on proton lifetime is 1.6^34 years (16 followed by 33 zeros) as reported by the Super-K experiment in Japan. This result rules out some of the grand unification theories (see the nice article by Natalie Wolchover)
- Latest results from the AMS-02 (Alpha Magnetic Spectrometer on the International Space Station) were announced. AMS-02 results indicate strong evidence for 1 Tev dark matter particles. However, it is also possible that the positron flux behavior at high energies as shown in the graphs below could be caused by positrons coming from the pulsars. We will know the final answer after 2024 (see the last graph) as the statistics improves. The best explanation of the AMS-02 results comes from the Turkish group participating in AMS-02. Here’s the essential graphs from their document: