Two-photon laser spectroscopy of antiprotonic helium and the antiproton-to-electron mass ratio

  title={Two-photon laser spectroscopy of antiprotonic helium and the antiproton-to-electron mass ratio},
  author={Masaki Hori and Anna O. Soter and D{\'a}niel Barna and Andreas J Dax and Ryugo Hayano and Susanne Friedreich and Bertalan Juh{\'a}sz and Thomas Pask and Eberhard Widmann and Dezso Horvath and Luca Venturelli and Nicola Zurlo},
Physical laws are believed to be invariant under the combined transformations of charge, parity and time reversal (CPT symmetry). This implies that an antimatter particle has exactly the same mass and absolute value of charge as its particle counterpart. Metastable antiprotonic helium (He+) is a three-body atom consisting of a normal helium nucleus, an electron in its ground state and an antiproton () occupying a Rydberg state with high principal and angular momentum quantum numbers… 
Two-photon spectroscopy of antiprotonic helium
The precision of laser spectroscopy of antiprotonic helium (a helium atom with one of its electrons replaced by an antiproton) has improved by almost 4 orders of magnitude over its 20 years of
Two-photon laser spectroscopy of antiprotonic helium atoms, and the antiproton-to-electron mass ratio
Some two-photon transitions in antiprotonic helium atoms at the deep UV wavelengths ? = 139.8?197.0 nm were recently studied by laser spectroscopy. The thermal Doppler broadening of the observed
Sub-Doppler Two-Photon Laser Spectroscopy of Antiprotonic Helium and the Antiproton-to-Electron Mass Ratio
The ASACUSA collaboration of CERN has recently irradiated antiprotonic helium atoms with two counter-propagating laser beams. This excited some non-linear two-photon transitions of the antiproton at
Recent progress of laser spectroscopy experiments on antiprotonic helium
  • M. Hori
  • Physics
    Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
  • 2018
By comparing the results with three-body quantum electrodynamics calculations, the antiproton-to-electron mass ratio was determined as , which agrees with the known proton- to-electrons mass ratio with a precision of 8×10−10.
Buffer-gas cooling of antiprotonic helium to 1.5 to 1.7 K, and antiproton-to–electron mass ratio
The extracted mass of the antiproton (relative to the electron mass) was in good agreement with previous measurements of the proton mass, in keeping with the implications of the combined charge, parity, and time-reversal symmetry of physical laws.
Determination of the Antiproton-to-Electron Mass Ratio by Two-Photon Laser Spectroscopy of Antiprotonic Helium Atoms
Some ultraviolet transition frequencies in antiprotonic helium atoms were measured by sub-Doppler two-photon laser spectroscopy to a precision of 2.3-5 parts in 109. By comparing the results with
Precision laser spectroscopy experiments on antiprotonic helium
At CERN‘s Antiproton Decelerator (AD) facility, the Atomic Spectroscopyand Collisions Using Slow Antiprotons (ASACUSA) collaboration is carrying out precise laser spectroscopy experiments on
High-resolution laser resonances of antiprotonic helium in superfluid 4He
When atoms are placed into liquids, their optical spectral lines corresponding to the electronic transitions are greatly broadened compared to those of single, isolated atoms. This linewidth increase
Precision measurement of the mass difference between light nuclei and anti-matter counterparts
In ultra relativistic heavy-ion collisions a large and similar amount of nuclei and anti-nuclei is produced in the central pseudorapidity region allowing one to thoroughly investigate their
Laser spectroscopy of pionic helium atoms
Long-lived pionic helium atoms (composed of a helium-4 nucleus, an electron and a negatively charged pion) are synthesized in a superfluid-helium target, as confirmed by laser spectroscopy involving the pion-occupied orbitals.


Antiprotonic helium and CPT invariance
We review recent progress in the laser and microwave spectroscopy of antiprotonic helium atoms carried out at CERN's Antiproton Decelerator facility (AD). Laser transitions were here induced between
Sub-ppm laser spectroscopy of antiprotonic helium and a CPT-violation limit on the antiprotonic charge and mass.
Six laser-resonant transitions have been detected in metastable antiprotonic helium atoms produced at the CERN Antiproton Decelerator, and it is deduced that the antiproten and proton charges and masses agree to within 6 x 10(-8) with a confidence level of 90%.
Trapped antihydrogen
T trapping of antihydrogen atoms is demonstrated and opens the door to precision measurements on anti-atoms, which can soon be subjected to the same techniques as developed for hydrogen.
Determination of the antiproton-to-electron mass ratio by precision laser spectroscopy of pHe+.
A femtosecond optical frequency comb and continuous-wave pulse-amplified laser were used to measure 12 transition frequencies of antiprotonic helium to fractional precisions of (9-16)x10(-9). One of
Direct measurement of transition frequencies in isolated pHe+ atoms, and new CPT-violation limits on the antiproton charge and mass.
A radio frequency quadrupole decelerator and achromatic momentum analyzer were used to decelerate antiprotons and produce p4He+ and p3He+ atoms in ultra-low-density targets, where collision-induced
Calculation of transition probabilities and ac Stark shifts in two-photon laser transitions of antiprotonic helium
Numerical ab initio variational calculations of the transition probabilities and ac Stark shifts in two-photon transitions of antiprotonic helium atoms driven by two counter-propagating laser beams
Testing CPT Invariance with Antiprotonic Helium Atoms
The structure of matter is related to symmetries at every level of study. CPT symmetry is one of the most important laws of field theory: it states the invariance of physical properties when one
Determination of the electron's atomic mass and the proton/electron mass ratio via Penning trap mass spectroscopy.
Accuracy of the electron's atomic mass has been improved tenfold by comparing cyclotron frequencies of electrons and single C6+ ions alternately confined to the same uniform magnetic field in a
Cyclotron frequency shifts arising from polarization forces
The general perturbation that is reported here affects the most precise mass comparisons attainable today, with applications including direct tests of Einstein's mass–energy relationship and charge-parity-time reversal symmetry, and possibly the weighing of chemical bonds.
The size of the proton
The root-mean-square charge radius, rp, has been determined with an accuracy of 2 per cent by electron–proton scattering experiments, and the present most accurate value of rp (with an uncertainty of 1 per cent) is given by the CODATA compilation of physical constants.