In this Letter, the first evidence of the 4((Lambda) over bar)(He) over bar antihypernucleus is presented, along with the first measurement at the LHC of the production of (anti)hypernuclei with mass number A = 4, specifically (anti)H-4(Lambda) and (anti)He-4(Lambda). In addition, the antiparticle-to-particle ratios for both hypernuclei (4((Lambda) over bar)(H) over bar /4(Lambda)H and 4((Lambda) over bar)(He) over bar/He-4(Lambda)) are shown, which are sensitive to the baryochemical potential of the strongly interacting matter created in heavy-ion collisions. The results are obtained from a data sample of central Pb-Pb collisions, collected during the 2018 LHC data taking at a center-of-mass energy per nucleon pair of root sNN = 5.02 TeV. The yields measured for the average of the charge-conjugated states are found to be [0.78 +/- 0.19(stat) +/- 0.17(syst)] x 10(-6) for the (anti)H-4(Lambda) and [1.08 +/- 0.34(stat) +/- 0.20(syst)] x 10(-6) for the (anti)He-4(Lambda), and the measured antiparticle-to-particle ratios are in agreement with unity. The presence of (anti)H-4(Lambda) and (anti)He-4(Lambda) excited states is expected to strongly enhance the production yield of these hypernuclei. The yield values exhibit a combined deviation of 3.3 sigma from the theoretical ground-state-only expectation, while the inclusion of the excited states in the calculations leads to an agreement within 0.6 sigma with the present measurements. Additionally, the measured (anti)H-4(Lambda) and (anti)He-4(Lambda) masses are compatible with the world-average values within the uncertainties.
First Measurement of A=4 Hypernuclei and Antihypernuclei at the LHC
De Falco, A.;Fionda, F. M.;Usai, G. L.;
2025-01-01
Abstract
In this Letter, the first evidence of the 4((Lambda) over bar)(He) over bar antihypernucleus is presented, along with the first measurement at the LHC of the production of (anti)hypernuclei with mass number A = 4, specifically (anti)H-4(Lambda) and (anti)He-4(Lambda). In addition, the antiparticle-to-particle ratios for both hypernuclei (4((Lambda) over bar)(H) over bar /4(Lambda)H and 4((Lambda) over bar)(He) over bar/He-4(Lambda)) are shown, which are sensitive to the baryochemical potential of the strongly interacting matter created in heavy-ion collisions. The results are obtained from a data sample of central Pb-Pb collisions, collected during the 2018 LHC data taking at a center-of-mass energy per nucleon pair of root sNN = 5.02 TeV. The yields measured for the average of the charge-conjugated states are found to be [0.78 +/- 0.19(stat) +/- 0.17(syst)] x 10(-6) for the (anti)H-4(Lambda) and [1.08 +/- 0.34(stat) +/- 0.20(syst)] x 10(-6) for the (anti)He-4(Lambda), and the measured antiparticle-to-particle ratios are in agreement with unity. The presence of (anti)H-4(Lambda) and (anti)He-4(Lambda) excited states is expected to strongly enhance the production yield of these hypernuclei. The yield values exhibit a combined deviation of 3.3 sigma from the theoretical ground-state-only expectation, while the inclusion of the excited states in the calculations leads to an agreement within 0.6 sigma with the present measurements. Additionally, the measured (anti)H-4(Lambda) and (anti)He-4(Lambda) masses are compatible with the world-average values within the uncertainties.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.


