Precision measurement of the mass difference between light nuclei and anti-nuclei

• Published in: Nature physics Vol. 11; no. 10; pp. 811 - 814
• Main Authors: Adam, J., Aphecetche, Laurent, Baldisseri, A., Batigne, Guillaume, Belikov, I., Borel, H., Castellanos, J. Castillo, Charvet, J.L., Cheshkov, C., Cheynis, B., Ducroux, L., Germain, Marie, Grossiord, J.-Y., Hippolyte, B., Lardeux, A., Maire, A., Martin Blanco, J., Martinez Garcia, Gines, Massacrier, L., Molnar, L., Moreira De Godoy, D.A., Morreale, A., Costa, H. Pereira Da, Pillot, Philippe, Ronflette, L., Schutz, Y., Shabetai, Alexandre, Stocco, Diego, Teyssier, B., Tieulent, R., Uras, A., Vernet, R., Wang, M., Conesa Balbastre, G., Faivre, J., Furget, C., Guernane, R., Kox, S., Real, J.S., Silvestre, C., Vauthier, A., Barret, V., Bastid, N., Batista Camejo, A., Crochet, P., Dupieux, P., Li, S., Lopez, X., Manso, F., Porteboeuf-Houssais, S., Rosnet, P., Vulpescu, B., Valle, Z. Conesa Del, Das, I., Espagnon, B., Hadjidakis, C., Lakomov, I., Suire, C., Takaki, J. D. Tapia, Tarhini, M., Valencia Palomo, L.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.10.2015; Nature Publishing Group; Nature Publishing Group (NPG)
• Subjects: 639/766/387/1126; 639/766/419/1131; Antiparticles; Atomic; Atomic physics; Charge; Classical and Continuum Physics; Complex Systems; Condensed Matter Physics; Detectors; Experimental nuclear physics; Experimental particle physics; Fysik; High Energy Physics - Experiment; Inversions; Ion exchangers; letter; Mathematical and Computational Physics; Molecular; Natural Sciences; Naturvetenskap; Nuclear Experiment; Nuclei; Nucleons; Optical and Plasma Physics; Physical Sciences; Physics; PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Quantum chromodynamics; Subatomic Physics; Subatomär fysik; Theoretical
• ISSN: 1745-2473; 1745-2481; 1476-4636
• DOI: 10.1038/nphys3432

The abundant production of (anti-)nuclei in relativistic heavy-ion collisions provides a platform to test the CPT invariance of nucleon–nucleon interactions—offering the highest precision measurement to date in the light-nuclei sector. The measurement of the mass differences for systems bound by the strong force has reached a very high precision with protons and anti-protons 1 , 2 . The extension of such measurement from (anti-)baryons to (anti-)nuclei allows one to probe any difference in the interactions between nucleons and anti-nucleons encoded in the (anti-)nuclei masses. This force is a remnant of the underlying strong interaction among quarks and gluons and can be described by effective theories 3 , but cannot yet be directly derived from quantum chromodynamics. Here we report a measurement of the difference between the ratios of the mass and charge of deuterons (d) and anti-deuterons ( ), and 3 He and nuclei carried out with the ALICE (A Large Ion Collider Experiment) 4 detector in Pb–Pb collisions at a centre-of-mass energy per nucleon pair of 2.76 TeV. Our direct measurement of the mass-over-charge differences confirms CPT invariance to an unprecedented precision in the sector of light nuclei 5 , 6 . This fundamental symmetry of nature, which exchanges particles with anti-particles, implies that all physics laws are the same under the simultaneous reversal of charge(s) (charge conjugation C), reflection of spatial coordinates (parity transformation P) and time inversion (T).