【物理】中性子がダークマターに崩壊している？ 二種実験の中性子の平均寿命の差から示唆
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Missing Neutrons May Lead a Secret Life as Dark Matter
Neutrons shouldn’t be all that mysterious. Found inside every atomic nucleus, they may seem downright mundane—but they have long confounded physicists who try to measure how long these particles can live outside of atoms.
For more than 10 years researchers have tried two types of experiments that have yielded conflicting results. Scientists have struggled to explain the discrepancy, but a new proposal suggests the culprit may be one of the biggest mysteries of all: dark matter.
Scientists are pretty sure the universe contains more matter than the stuff we can see, and their best guess is that it takes the form of invisible particles.
What if neutrons are decaying into these invisible particles? This idea, put forward by University of California, San Diego, physicists Bartosz Fornal and Benjamin Grinstein in a paper posted this month to the physics preprint site arXiv.org, would explain why one type of neutron experiment consistently measures a different value than the other.
If true, it could also provide the first way to access the dark matter particles physicists have long been seeking to no avail.
Dark Matter Interpretation of the Neutron Decay Anomaly
https://arxiv.org/abs/1801.01124
続く
The idea has already gripped many researchers making neutron lifetime measurements, and some have quickly scrambled to look for evidence of it in their experiments. If neutrons are turning into dark matter, the process could also produce gamma-ray photons, according to Fornal and Grinstein’s calculations.
“We have some germanium gamma-ray detectors lying around,” says Christopher Morris, who runs neutron experiments at Los Alamos National Laboratory.
By serendipity, he and his team just recently installed a large tank to collect neutrons on their way from the start of the experiment to the point where physicists try to measure their lifetimes.
This tank provided a large holding cell where many neutrons might decay into dark particles, if the pOnly one of the two types of neutron decay experiments would be sensitive to neutrons decaying into dark matter.
This type, called “bottle experiments,” essentially puts a given number of neutrons into a “bottle” with magnetic walls that holds them inside, then counts how many are left after a certain amount of time.
Through many measurements the researchers can calculate how long an average neutron lives.
The other type of experiment looks for the main product of neutron decays.
Through a well-known process called beta decay, a neutron outside of an atomic nucleus will break down into a proton, an electron and an antimatter neutrino. So-called “beam” experiments shoot a beam of neutrons into a magnetic trap that catches positively charged protons.
Researchers count how many neutrons go in and how many protons come out after a given time, then infer the average time it takes a neutron to decay.
つづく
Both classes of experiments find neutrons can last for only about 15 minutes outside of atoms.
But bottle experiments measure an average of 879.6 seconds plus or minus 0.6 second, according to the Particle Data Group, an international statistics-keeping collaboration.
Beam experiments get a value of 888.0 seconds plus or minus 2.0 seconds. The 8.4-second difference may not seem like much, but it is larger than either of the calculations’ margins of error—which are based on the experimenters’ understanding of all the sources of uncertainty in their measurements.
The difference leaves the two figures with a statistically significant “4-sigma” deviation. Experimenters behind both methods have scoured their setups for overlooked problems and sources of uncertainty, with no luck so far.
But if neutrons can transform in more ways than just beta decay, it would explain why bottle and beam experiments do not find the same answers.
Fornal and Grinstein suggest that occasionally neutrons turn into some type of dark particle, undetectable by traditional means.
The bottle experiments would then measure a slightly shorter lifetime for the neutron than beam experiments, because the former would be counting the dark matter decays in addition to the beta decays—and thus detecting a larger number of total decays in any given time period.
The beam setup, however, only measures how long it takes neutrons to turn into protons, so their tally would not include dark matter decays and would therefore suggest neutrons can stick around slightly longer.
And that is indeed what the two methods show.rocess in fact occurs, and produce gamma-rays as a by-product.
“When we heard about this paper, we took our detector and set it up next to our big tank and started looking for gamma rays.”
He and his team are still analyzing the results of this trial, but hope to have a paper out in a few weeks reporting on what they found.
この続きはリンクから
https://www.scientificamerican.com/article/missing-neutrons-may-lead-a-secret-life-as-dark-matter/ あのダークマターね、やっぱブラックサンダーの方が美味いわ 要約するとチュウしたら精子がダーッとマタから崩壊したってこと これ、火葬しなければ違うもんになってるかも知れないって事だな。 IQたった160程度の猿共がようやく重力の秘密を読み解く入り口に辿り着いたな
褒めてつかわす はいはい示唆示唆
最近の論文は権威がありゃなんでもかんでも事実かどうか分かんないけどそうかもね？っていっときゃもてはやされるもんな >The bottle experiments would then measure a slightly shorter lifetime for the neutron than beam experiments,
>because the former would be counting the dark matter decays in addition to the beta decays
>;and thus detecting a larger number of total decays in any given time period.
双子の兄弟が居て、兄は39歳で禿げて弟は40歳で禿げた
この1歳の差は兄の抜け毛の一部がダークマターであるからではないか？
みたいな話でしょ？
ちょっと強引じゃね 素粒子は空間割り込み
重力は空間の復原力
だから質量が大きいほど重力が大きい そうか、二重実験の中性子の平均寿命の差ってわけだな 宇宙の始まりとか果てとか
その外側とか考えると気が狂いそうになる 南野陽子と佐野量子、パーティクルシスターズ
さすがに中性子はいないだろうな… >>21
昔からだし、概念が細分化された結果予測も多岐に渡るわけだ。それを証明するのも過去からの繰り返しだろう。 >>47
つまり女は金玉袋より胃袋を制した者が勝つってことか
深いな 中性子って外乱がなくてもたった137億年で崩壊するものなの？ ああ、勘違いしてたわ
中性子の半減期は15分だっけ >>1
やはりそういうことだったのか
予想した通りだな >>13
複合粒子としての電子は「composite electron」と呼ばれる
昔からあるアイディアらしいが、今のところ電子が複合粒子であるという証拠は見つかっていない
「LHCで発見が期待される物理現象リスト」では、ヒッグス粒子や
超対称性粒子のずっと下の方ではあるがランクインしてた うむ、やはりそうだったか。俺も以前からそう思っていたんだ。 ■ このスレッドは過去ログ倉庫に格納されています
