(AGENPARL) - Roma, 25 Settembre 2024 - (AGENPARL) – mer 25 settembre 2024 CERN PRESS RELEASE
NA62 experiment at CERN observes ultra-rare particle decay
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The NA62 experiment at CERN (Image: CERN)
In the Standard Model of particle physics, the odds of this decay occurring are less than one in 10 billion
“This observation is the culmination of a project that started more than a decade ago,” says NA62 spokesperson Giuseppe Ruggiero. “Looking for effects in nature that have probabilities of happening of the order of 10^-11 is both fascinating and challenging. After rigorous and painstaking work, we have finally seen the process NA62 was designed and built to observe.”
But why are physicists looking for a process that occurs so rarely? The reason is that theoretical models suggest that the K+??+?? decay is extremely sensitive to deviations from the Standard Model prediction, making it one of the most interesting processes to search for evidence of new physics beyond the Standard Model.
Analysing data collected by the NA62 detector between 2016 and 2022, the NA62 researchers measured the fraction of K+ that decay in this way to be 13.0[-2.9]^+3.3×10^-11. With a relative precision of 25%, this is the most precise measurement of the K+??+?? decay to date.
The result is about 50% larger than the Standard Model prediction but is compatible with it given the overall uncertainty. With data taking ongoing, NA62 is set to be able to test the possibility of new physics in this decay within the next few years.
“Searching for hints of new physics in this decay requires more data, but this result is a leap forward and further strengthens the strong interest in this line of research,” says NA62 physics coordinator Karim Massri.
Crucial to this result was the data from 2021 and 2022, which was taken following the completion of detector upgrades that enabled NA62 to operate at 30% higher beam intensities. Combined with improvements to data-analysis techniques, these hardware upgrades enabled the collection of signal candidates 50% faster than before, while adding new tools to suppress the background processes that could mimic the K+??+?? decay.
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