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Here\u2019s what you\u2019ll learn when you read this study:<\/p>\n
In the beginning of the universe, matter somehow outmaneuvered antimatter, creating the stuff-filled universe we know and love today.<\/p>\n
Scientists from two large long-baseline experiments in the U.S. and Japan have joined forces to study neutrinos\u2014elusive particles that might be responsible for matter conquering antimatter\u2014in even greater detail.<\/p>\n
While the data doesn\u2019t discern whether or not neutrinos are behind this mystery, the study shows that large collaborations between experiments can help push scientists closer to the answer.<\/p>\n
One of the biggest mysteries of the universe<\/a> is why you, or I, or the galaxy, or the universe itself for that matter (no pun intended) exists at all. According to CERN\u2014the beating heart of nuclear research on planet Earth\u2014\u201cmatter and antimatter particles are always produced as a pair and, if they come in contact, annihilate one another, leaving behind pure energy.\u201d<\/p>\n So, the reasoning goes that after those hot and dense microseconds of the universe\u2019s chaotic origin story, the afterbirth should\u2019ve simply been pure energy<\/a>. But, as you and I are evidence of, that\u2019s not what happened.<\/p>\n The reason why matter won out in the end has been the subject of intense scientific study for decades, and one of the particles that could be vital to unlocking this 13.8 billion-year-old mystery is the neutrino. The problem is, neutrinos<\/a> are far from willing participants in this search for answers, given how difficult they are to observe. Neutrinos are nearly massless and they interact with almost nothing\u2014in fact, every second, 100 trillion of them pass through your body, but only a handful will interact with you during your entire lifetime (not that you\u2019ll notice). Simply put, neutrinos are as close to invisible as you can possibly get without being fully impossible to directly detect.<\/p>\n To better understand neutrinos, two large-scale experiments\u2014T2K in Japan and NOvA in the U.S.\u2014have joined forces to combine their data<\/a> and perform an in-depth analysis of how these particles could have enabled matter to exist in the universe. The results of this unprecedented collaboration were reported in the journal Nature<\/a>.<\/p>\n \u201cBy making a joint analysis you can get a more precise measurement than each experiment can produce alone,\u201d Liudmila Kolupaeva, a NOvA collaborator and co-author of the study, said in a press statement<\/a>. \u201cAs a rule, experiments in high-energy physics<\/a> have different designs even if they have the same science goal. Joint analyses allow us to use complementary features of these designs.\u201d<\/p>\n In the study, scientists focused on a concept known as \u201cneutrino mass ordering<\/a>.\u201d As the authors note, neutrinos exist in three mass states (\u03bd1, \u03bd2, and \u03bd3), and each flavor of neutrino (electron, muon, or tau) is a mixture of those states. Neutrino mass ordering is an attempt to determine whether, of the three mass states, two are heavy and one is light, or two are light and one is heavy. \u201cNormal\u201d mass ordering means that there are two light mass states and one heavy mass state, while an inverted arrangement implies the opposite<\/a>.<\/p>\n If the \u201cnormal\u201d mass ordering holds, muon neutrinos are more likely to become electron neutrinos, and their antimatter counterparts are less likely. But, of course, the opposite is true when inverted. The idea is that if the inverted pattern holds, then it\u2019s possible for matter-antimatter pairs to violate charge-pair (CP) symmetry. Unfortunately, this particular combination of data doesn\u2019t show a particular preference for either mass ordering, so the mystery<\/a> still remains. But the ability for these two projects\u2014both long-baseline experiments\u2014to combine data is a major win for particle physics moving forward.<\/p>\n