Measurement of the full excitation spectrum of the 7Li(p,γ)αα reaction at 441 keV

Münch, M.; Kirsebom, O. S.; Swartz, J. A.; Riisager, K.; Fynbo, H. O. U.

doi:10.1016/j.physletb.2018.06.013

Cited by 12 publications

(8 citation statements)

References 24 publications

(58 reference statements)

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“…Recent observation [1] of a light, neutral boson decaying into an e + e − pair with a mass of about 17 MeV, in the decay of the I(J π ) = 0(1 + ) state of 8 Be at Atomki, has generated a great deal of interest [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Supporting evidence for this hypothetical X17 particle has been reported recently in the decay of the excited I(J π ) = 0(0 − ) state of 4 He [16].…”

Section: Introductionmentioning

confidence: 99%

“…Earlier observations of similar e + e − pairs with invariant masses between 3 to 20 MeV in the collision of nuclei with emulsion detectors have been reported [17][18][19][20][21][22]. Different theoretical interpretations, astrophysical implications, and experimental searches have been presented [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. However, a definitive description of the X17 particle has not yet emerged.…”

Section: Introductionmentioning

confidence: 99%

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Open string QED meson description of the X17 particle and dark matter

Wong

2020

J. High Energ. Phys.

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As a quark and an antiquark cannot be isolated, the intrinsic motion of a composite qq system in its lowest-energy states lies predominantly in 1+1 dimensions, as in an open string with the quark and the antiquark at its two ends. Accordingly, we study the lowest-energy states of an open string qq system in QCD and QED in 1+1 dimensions. We show that π 0 , η, and η can be adequately described as open string qq QCD mesons. By extrapolating into the qq QED sector in which a quark and an antiquark interact with the QED interaction, we find an open string isoscalar I(J π) = 0(0 −) QED meson state at 17.9±1.5 MeV and an isovector (I(J π) = 1(0 −), I 3 = 0) QED meson state at 36.4±3.8 MeV. The predicted masses of the isoscalar and isovector QED mesons are close to the masses of the hypothetical X17 and E38 particles observed recently, making them good candidates for these particles. The decay products of QED mesons may show up as excess e + e − and γγ pairs in the anomalous soft photon phenomenon associated with hadron productions in high-energy hadron-proton collisions and e +-e − annihilations. Measurements of the invariant masses of excess e + e − and γγ pairs will provide tests for the existence of the open string qq QED mesons. An assembly of gravitating QED mesons are expected to emit electron-positron pairs and/or gamma rays and their decay energies and lifetimes will be modified by their gravitational binding energies. Consequently, a self-gravitating isoscalar QED meson assembly whose mass M and radius R satisfy (M/M)/(R/R) 4.71 × 10 5 will not produce electron-positron pairs nor gamma rays and may be a good candidate for the primordial dark matter.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Open string QED meson description of the X17 particle and dark matter

Wong

2020

J. High Energ. Phys.

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“…In addition to reproducing the known 8 Be states, the SA-NCSM calculations also predict a low-lying, 2 + α + α state with a width of 10(3) MeV (calculated using a NNLO opt chiral potential) [29], which would be accessible to 8 Li via allowed β decay. There has been an ongoing debate about the existence of this so-called "intruder state," though experimental evidence remains inconclusive [21,25,[30][31][32][33][34][35][36][37]. This measurement was also unable to reach a conclusion on the intruder resonance's existence based on R-matrix fitting.…”

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confidence: 83%

Improved Limit on Tensor Currents in the Weak Interaction from $^8$Li $β$ Decay

Burkey,

Savard,

Gallant

et al. 2022

Preprint

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The electroweak interaction in the Standard Model (SM) is described by a pure vector-axialvector structure, though any Lorentz-invariant component could contribute. In this work, we present the most precise measurement of tensor currents in the low-energy regime by examining the β-ν correlation of trapped 8 Li ions with the Beta-decay Paul Trap. We find a βν = −0.3325±0.0013stat ± 0.0019syst at 1σ for the case of coupling to right-handed neutrinos (CT = −C T ), which is consistent with the SM prediction.

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“…These excitation energies agree with the SA-NCSM extrapolated results given the error bars [4], as well as with the predicted widths. In addition, a recent experimental study has found a tentative evidence for a broad 0 + state at 12 MeV, prompting a need for further measurements [17]. Various earlier ab initio studies have seen intruder 0 + and 2 + states as well [18][19][20].…”

Section: LI Beta Decaymentioning

confidence: 99%

Shape Mixing and Clustering in Nuclei: Probing Physics beyond the Standard Model

Sargsyan¹

2022

Bulg.J.Phys.

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The ab initio methods in nuclear physics play a major role due to their use of realistic internucleon interactions that grant them predictive capabilities. One of these models -the symmetry-adapted nocore shell model (SA-NCSM) -is capable of reaching the medium-mass region of the chart of the nuclides, by exploiting the emergent symmetries of nuclei, and is therefore well-suited for studying collective correlations and beta decay modes. We apply the SA-NCSM to calculate beta-decay observables essential to probe physics beyond the Standard Model. Our calculations of higher-order recoil terms in the beta decay of 8 Li help to significantly reduce the uncertainties in high-precision experiments that study the vector minus axial vector (V−A) structure of the weak interaction. Furthermore, we calculate neutrinoless double beta decay matrix elements important for determining whether the neutrino is its own antiparticle.

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Measurement of the full excitation spectrum of the 7Li(p,γ)αα reaction at 441 keV

Cited by 12 publications

References 24 publications

Open string QED meson description of the X17 particle and dark matter

Open string QED meson description of the X17 particle and dark matter

Improved Limit on Tensor Currents in the Weak Interaction from $^8$Li $β$ Decay

Shape Mixing and Clustering in Nuclei: Probing Physics beyond the Standard Model

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