The measurement of the mass di erences for systems bound by the strong force has reached a very high precision with protons and anti-protons1,2. The extension of such measure- ment from (anti-)baryons to (anti-)nuclei allows one to probe any di erence 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 e ective theories3, but cannot yet be directly derived from quantum chromodynamics. Here we report a measurement of the di erence between the ratios ofthemassandchargeofdeuterons(d)andanti-deuterons(d ̄), and 3He and 3He 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 di erences confirms CPT invariance to an unprecedented precision in the sector of light nuclei5,6. 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).

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

CAMERINI, Paolo;FRAGIACOMO, ENRICO;LEA, RAMONA;LUPARELLO, GRAZIA;MARGAGLIOTTI, GIACOMO;PIANO, STEFANO;RUI, RINALDO;
2015

Abstract

The measurement of the mass di erences for systems bound by the strong force has reached a very high precision with protons and anti-protons1,2. The extension of such measure- ment from (anti-)baryons to (anti-)nuclei allows one to probe any di erence 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 e ective theories3, but cannot yet be directly derived from quantum chromodynamics. Here we report a measurement of the di erence between the ratios ofthemassandchargeofdeuterons(d)andanti-deuterons(d ̄), and 3He and 3He 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 di erences confirms CPT invariance to an unprecedented precision in the sector of light nuclei5,6. 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).
http://www.nature.com/nphys/index.html
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11368/2866106
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