1/4/2024 0 Comments Boson x steam hackWhen the Atomki group studied the same 17.64 MeV transition, they found that a key background component-subdominant E1 decays from nearby excited states-dramatically improved the fit and were not included in the original de Boer analysis. Right: the same analysis for the M1 internal pair creation events from the 17.64 MeV beryllium-8 states. The “signal – background” now shows a broad excess across all opening angles. This transition has similar energy splitting to the beryllium-8 17.64 MeV transition and shows good agreement with the expectations as shown by the flat “signal – background” on the bottom panel. The de Boer claim for a 10 MeV new particle. Left: distribution of opening angles for internal pair creation events in an E1 transition of carbon-12. The proposed evidence for “de Boeron” is shown below: These claims didn’t pan out, and in fact the instrumentation paper by the Atomki experiment rules out that original anomaly. de Boer made strong claims about evidence for a new 10 MeV particle in the internal pair creation decays of the 17.64 MeV beryllium-8 excited state. Some physicists are concerned that beryllium may be the ‘ boy that cried wolf,’ and point to papers by the late Fokke de Boer as early as 1996 and all the way to 2001. Indeed, the conservative bet would be some not-understood systematic effect, akin to the 130 GeV Fermi γ-ray line. This means that it’s highly unlikely to be a statistical fluctuation, as the 750 GeV diphoton bump appears to have been. The opening angle bump would then be interpreted as a new particle with mass of roughly 17 MeV. To match the observed number of anomalous events, the rate at which the excited beryllium decays via the X boson must be 6×10 -6 times the rate at which it goes into a γ-ray. This relates the mass of the proposed new particle, X, to the opening angle θ and the energies E of the electron and positron. Image from 1608.03591.Īs an exercise for those with a background in special relativity, one can use the relation (p e + + p e –) 2 = m X 2 to prove the result: Some of these decays are mediated by the new X particle, which then decays in to electron–positron pairs of a certain opening angle that are detected in the Atomki pair spectrometer detector. These decay into the beryllium-8 ground state. In summary: protons of a specific energy bombard stationary lithium-7 nuclei and excite them to the 18.15 MeV beryllium-8 state. Schematic of the Atomki experiment and new particle ( X) interpretation of the anomalous events. There are three nuclear states to be aware of: the ground state, the 18.15 MeV excited state, and the 17.64 MeV excited state. They can have excited states analogous to the excited states of at lowoms, which are bound states of nuclei and electrons. The particular nucleus of interest is beryllium-8, which has four neutrons and four protons, which you may know from the triple alpha process. Nuclei are bound states of protons and neutrons. Recently there’s some press (see links below) regarding early hints of a new particle observed in a nuclear physics experiment. In this bite, we’ll summarize the result that has raised the eyebrows of some physicists, and the hackles of others. Feng et al., “Protophobic Fifth-Force Interpretation of the Observed Anomaly in 8Be Nuclear Transitions” (phenomenology 1604.07411 PRL)Įditor’s note: the author is a co-author of the paper being highlighted. Krasznahorkay et al., “Observation of Anomalous Internal Pair Creation in 8Be: A Possible Indication of a Light, Neutral Boson” (experimental result 1504.01527 PRL version note PRL version differs from arXiv) Gulyás et al., “A pair spectrometer for measuring multipolarities of energetic nuclear transitions” (description of detector 1504.00489 NIM)
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