Precision measurement of the mass difference between light nuclei and anti-nuclei.
Journal article
Authors | ALICE Collaboration and Barnby, Lee |
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Abstract | The measurement of the mass differences for systems bound by the strong force has reached a very high precision with protons and anti-protons. 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, 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 (d-bar ), and 3He 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. 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). |
The measurement of the mass differences for systems bound by the strong force has reached a very high precision with protons and anti-protons. 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, 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 (d-bar ), and 3He 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. 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). | |
Keywords | Large hadron collider; Relativistic heavy ion collisions; Charge parity time reversal (CPT) |
Year | 2015 |
Journal | Nature Physics |
Publisher | Springer Nature |
ISSN | 17452473 |
17452481 | |
Digital Object Identifier (DOI) | https://doi.org/10.1038/nphys3432 |
Web address (URL) | http://hdl.handle.net/10545/622334 |
hdl:10545/622334 | |
Publication dates | 17 Aug 2015 |
Publication process dates | |
Deposited | 15 Mar 2018, 16:49 |
Rights | Archived with thanks to Nature Physics |
Contributors | University of Birmingham |
File | File Access Level Open |
File | File Access Level Open |
https://repository.derby.ac.uk/item/950zw/precision-measurement-of-the-mass-difference-between-light-nuclei-and-anti-nuclei
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