NA62 experiment at CERN observes ultra-rare particle decay

Within the Same old Style of particle physics, the percentages of this decay going on are lower than one in 10 billion

Geneva, 25 September 2024. At a seminar held at CERN this week, the NA62 collaboration reported the unequivocal affirmation of the ultra-rare decay of a definitely charged kaon right into a definitely charged pion and a neutrino–antineutrino pair. Experiments together with NA62 have prior to now measured and noticed proof of this procedure, however that is the primary time it’s been measured with a statistical importance of 5 usual deviations, crossing the edge historically required to assert a discovery in particle physics.

Denoted by means of Okay+→π+νν, this decay is likely one of the rarest particle processes ever seen: within the Same old Style of particle physics, lower than one in 10 billion definitely charged kaons are predicted to decay on this manner.

“This remark is the end result of a venture that began greater than a decade in the past,” says NA62 spokesperson Giuseppe Ruggiero. “In search of results in nature that experience chances of taking place of the order of 10-11 is each interesting and difficult. After rigorous and painstaking paintings, now we have in the end noticed the method NA62 was once designed and constructed to look at.”

However why are physicists on the lookout for a procedure that happens so hardly? The reason being that theoretical fashions counsel that the Okay+→π+νν decay is terribly delicate to deviations from the Same old Style prediction, making it one of the attention-grabbing processes to seek for proof of latest physics past the Same old Style.

Analysing records accumulated by means of the NA62 detector between 2016 and 2022, the NA62 researchers measured the fraction of Okay+ that decay on this solution to be 13.0 +3.3
-2.9 × 10-11. With a relative precision of 25%, that is probably the most exact size of the Okay+→π+νν decay thus far.

The result’s about 50% better than the Same old Style prediction however is appropriate with it given the entire uncertainty. With records taking ongoing, NA62 is ready in an effort to take a look at the opportunity of new physics on this decay inside of the following couple of years.

“On the lookout for hints of latest physics on this decay calls for extra records, however this result’s a bounce ahead and additional strengthens the robust passion on this line of study,” says NA62 physics coordinator Karim Massri.

Within the NA62 experiment, kaons are produced by means of slamming a high-intensity proton beam from CERN’s Tremendous Proton Synchrotron right into a desk bound goal. Because of this, nearly one thousand million secondary debris are produced each and every 2d, and those fly into the NA62 detector. Of those debris, about 6% are definitely charged kaons. NA62 exactly detects the decay merchandise of kaons, figuring out and measuring the entire debris produced aside from the neutrinos, whose presence is deduced from their lacking power.

The most important to this consequence was once the knowledge from 2021 and 2022, which was once taken following the of entirety of detector upgrades that enabled NA62 to perform at 30% upper beam intensities. Mixed with enhancements to data-analysis ways, those {hardware} upgrades enabled the number of sign applicants 50% quicker than earlier than, whilst including new equipment to suppress the background processes that might mimic the Okay+→π+νν decay.

“This size depends upon figuring out the one-in-10-billion Okay+ decay this is our sign and ensuring it’s not one of the vital different 9 999 999 999 decays that may mimic the sign,” says lead records analyst Joel Swallow. “The entire NA62 collaboration has made this nearly unimaginable consequence conceivable.”