Precision measurement of the mass difference between light nuclei and anti-nuclei with the ALICE experiment at the LHC

Collaboration
Aug 17, 2015
22 pages
Published in:
  • Nature Phys. 11 (2015) 10, 811-814
  • Published: 2015
    and
  • Published: Aug 17, 2015
e-Print:
Report number:
  • ALICE-PUBLIC-2015-002,
  • CERN-PH-EP-2015-035
Experiments:

Citations per year

20152018202120242025024681012
Abstract: (CDS)
We report on a measurement of the difference Δμ=Δ(m/z)\Delta \mu = \Delta (m / |z|) between the mass-over-charge ratio of deuteron (d) and anti-deuteron (d\overline{\rm d}), and 3He^3{\rm He} and 3He^3{\overline{\rm He}} nuclei, carried out with ALICE (A Large Ion Collider Experiment) in Pb-Pb collisions at a centre-of-mass energy per nucleon pair sNN= 2.76 TeV\sqrt{s_{\rm NN}}=~2.76~\rm{TeV}. Our measurement yields Δμddˉ/μd=[0.9±0.5(stat.)±1.4(syst.)]×104{\Delta \mu}_{\rm{d\bar{d}}}/{\mu}_{\rm{d}} = [0.9 \pm 0.5 (\rm{stat.}) \pm 1.4 (\rm{syst.})] \times 10^{-4} and Δμ3He3He/μ3He=[1.2±0.9(stat.)±1.0(syst.)]×103{\Delta \mu}_{\rm{^{3}He ^{3}\overline{He}}}/{\mu}_{\rm{^{3}He}} = [-1.2 \pm 0.9 (\rm{stat.}) \pm 1.0 (\rm{syst.})] \times 10^{-3}. Combining these results with existing measurements of the masses of the (anti-)nucleons, the relative binding energy differences are extracted, Δεddˉ/εd=0.04±0.05(stat.)±0.12(syst.){\Delta \varepsilon}_{\rm{d\bar{d}}}/{\varepsilon}_{\rm{d}} = -0.04 \pm 0.05(\rm{stat.}) \pm 0.12(\rm{syst.}) and Δε3He3He/ε3He=0.24±0.16(stat.)±0.18(syst.){\Delta \varepsilon}_{\rm{^{3}He ^{3}\overline{He}}}/{\varepsilon}_{\rm{^{3}He}} = 0.24 \pm 0.16(\rm{stat.}) \pm 0.18(\rm{syst.}). These results test, to an unprecedented precision, the CPT invariance in the sector of light nuclei.
Note:
  • QCD
  • relativistic heavy ion physics
  • conservation law tests
  • mass difference
  • light nucleus
  • nucleus: mass
  • antinucleus
  • precision measurement
  • parity: transformation
  • particle: exchange