The standard model of particle physics predicts an asymmetry between matter and antimatter known as charge parity (CP) violation. However, the size of this asymmetry in the Standard Model is not large enough to explain the disequilibrium, and so far the asymmetry has only been observed in certain decays of particles called mesons. In two new studies, LHCb collaboration CERN’s Large Hadron Collider (LHC) has discovered evidence of CP violation in baryon decay and beauty hadron decay into charmonium particles, shedding light on these two pieces of the matter-antimatter puzzle.
Exterior view of the LHCb detector. Image credit: CERN.
Experiments involving LHCb have previously searched for baryon CP violation by looking for differences in the way matter and antimatter baryons decay into other particles.
However, these investigations have so far been essentially empty-handed.
One LHCb study provided evidence for a process in the specific collapse of the bottom lambda baryon, but subsequent studies analyzing larger samples of such collapses did not increase that evidence.
in first new studyLHCb physicists scrutinized proton-proton collision data obtained during the first and second runs of the LHC and discovered various decay modes of the bottom lambda baryon, including decay into a lambda baryon and two kaons. You have searched for
We then investigated the CP violation in each decay mode, essentially by counting the number of decays of the bottom lambdabaryon and its antimatter partner and taking the difference between the two.
In the case of the lambda baryon and its decay into two kaons, this difference showed evidence of a CP violation with a significance of 3.2 standard deviations.
in second studythe LHCb team focused on the decay of a beautiful charged meson into J/psi and a charged pion.
J/psi is a charmmonium particle, a meson consisting of a charm quark and a charm antiquark.
We performed an analysis similar to the lower lambda baryon study, also using data from the first and second runs of the LHC, and found evidence for CP violation in this decay mode of charged meons. Again, the significance is 3.2 standard. Deviation.
This finding represents evidence of CP violation in the decay of beauty hadrons to charmonium particles.
“Our study represents an important step toward establishing whether CP violations are present in these types of collapses,” the authors state.
“Data from the high-luminosity LHC, with its third experiment and planned collider upgrades, will shed further light on these and other parts of the matter-antimatter puzzle. .”
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LHCb collaboration. 2024. Study of Λ0b and Ξ0b decay to Λh+h'- and evidence of CP violation in Λ0b→ΛK+K- decay. arXiv: 2411.15441
LHCb collaboration. 2024. First evidence of direct CP violation to charmonium decay in cosmetology. arXiv: 2411.12178
Source: www.sci.news
