Hunting down the X17 boson at the CERN SPS

Depero, E.; Andreev, Yu.; Banerjee, D.; Bernhard, J.; Burtsev, V.E.; Charitonidis, N.; Chumakov, A.G.; Cooke, D.; Dermenev, A.; Donskov, S.V.; Dusaev, R. R.; Enik, T.; Feshchenko, A.; Фролов, В.; Gardikiotis, A.; Gerassimov, S.; Girod, S.; Gninenko, S.; Hösgen, M.; Качанов, В.; Karneyeu, A.; Kekelidze, G. D.; Ketzer, B.; Kirsanov, M.; Kolosov, V.N.; Konorov, I.; Kovalenko, Sergey; Kramarenko, V. A.; Kravchuk, L.; Krasnikov, N.; Kuleshov, S.; Lyubovitskij, Valery E.; Lysan, V.; Matveev, V.; Mikhailov, Yu.V.; Peshekhonov, D.V.; Polyakov, V.A.; Radics, B.; Rojas, R. A.; Rubbia, A.; Samoylenko, V.D.; Shchukin, Dmitry G.; Sieber, H.; Tikhomirov, V. O.; Tlisova, vI.; Tlisov, D.; Toropin, A.; Trifonov, A. Yu.; Vasilishin, B. I.; Vasquez, G. A.; Volkov, P.; Volkov, V.; Ulloa, P.

doi:10.1140/epjc/s10052-020-08725-x

Cited by 19 publications

(14 citation statements)

References 78 publications

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“…In this IR model, requirement (ii) mentioned above has been imposed by fiat. Requirement (i) follows from the axion's coupling to e + e − , which dominates its decay width: [65], whereas the lower bound is set by the 2019 results from CERN's SPS NA64 fixed target experiment [66,67], constraining the axion lifetime to τ a 0.4 × 10 −13 s. The sensitivities of future experiments to the axion's electronic couplings (such as fixed targets and e + e − colliders) have been explored in [45].…”

Section: Brief Overview Of the Piophobic Qcd Axionmentioning

confidence: 99%

Signals of the QCD axion with mass of 17 MeV/c^2: nuclear transitions and light meson decays

Alves

2020

Preprint

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The QCD axion remains experimentally viable in the mass range of O(10 MeV) if (i) it couples predominantly to the first generation of SM fermions; (ii) it decays to e + e − with a short lifetime τ a 4 × 10 −14 s; and (iii) it has suppressed isovector couplings, i.e., if it is piophobic. Interestingly, these are precisely the properties required to explain recently observed anomalies in nuclear de-excitations, to wit: the e + e − emission spectra of isoscalar magnetic transitions of 8 Be and 4 He nuclei showed a "bump-like" feature peaked at m e + e − ∼ 17 MeV. In this article, we argue that on-shell emission of the QCD axion (with the aforementioned properties) provides an extremely well-motivated, compatible explanation for the observed excesses in these nuclear de-excitations. The absence of anomalous features in other measured transitions is also naturally explained: piophobic axion emission is strongly suppressed in isovector magnetic transitions, and forbidden in electric transitions. This QCD axion hypothesis is further corroborated by an independent observation: a ∼ 2 − 3 σ deviation in the measurement of Γ(π 0 → e + e − ) from the SM theoretical expectation. This article also includes detailed estimations of various axionic signatures in rare light meson decays, which take into account contributions from low-lying QCD resonance exchange, and, in the case of rare Kaon decays, the possible effective implementations of ∆S = 1 octet-enhancement in chiral perturbation theory. These inherent uncertainties of the effective description of the strong interactions at low energies result in large variations in the predictions for hadronic signals of the QCD axion; in spite of this, the estimated ranges for rare meson decay rates obtained here can be probed in the near future in η/η and Kaon factories.

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Section: Brief Overview Of the Piophobic Qcd Axionmentioning

confidence: 99%

Signals of the QCD axion with mass of 17 MeV/c^2: nuclear transitions and light meson decays

Alves

2020

Preprint

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“…9 together with the current constraints from other experiments. The NA64 results exclude the X17 as an explanation for the ATOMKI anomaly for the X17 − e − vector coupling e 6.8 × 10 −4 and mass value of 16.7 MeV [362], leaving the still unexplored region 6.8 ×10 −4 e 1.4×10 −3 as quite an exciting prospect for future searches [363].…”

Section: Na64mentioning

confidence: 92%

Feebly-Interacting Particles:FIPs 2020 Workshop Report

Agrawal,

Bauer,

Beacham

et al. 2021

Preprint

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With the establishment and maturation of the experimental programs searching for new physics with sizeable couplings at the LHC, there is an increasing interest in the broader particle and astrophysics community for exploring the physics of light and feebly-interacting particles as a paradigm complementary to a New Physics sector at the TeV scale and beyond. FIPs 2020 has been the first workshop fully dedicated to the physics of feebly-interacting particles and was held virtually from 31 August to 4 September 2020. The workshop has gathered together experts from collider, beam dump, fixed target experiments, as well as from astrophysics, axions/ALPs searches, current/future neutrino experiments, and dark matter direct detection communities to discuss progress in experimental searches and underlying theory models for FIPs physics, and to enhance the cross-fertilisation across different fields. FIPs 2020 has been complemented by the topical workshop "Physics Beyond Colliders meets theory", held at CERN from 7 June to 9 June 2020. This document presents the summary of the talks presented at the workshops and the outcome of the subsequent discussions held immediately after. It aims to provide a clear picture of this blooming field and proposes a few recommendations for the next round of experimental results.a Member of the Organising Committee of FIPs2020 workshop, https://indico.cern.ch/event/864648/.b Member of the Organising Committee of "PBC meets theory" workshop, https://indico.cern.ch/event/910753/.

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“…12 together with the current constraints from other experiments. The NA64 results exclude the X17 as an explanation for the ATOMKI anomaly for the X 17−e − vector coupling e 6.8×10 −4 and mass value of 16.7 MeV [378], leaving the still unexplored region 6.8 ×10 −4 e 1.4 × 10 −3 as quite an exciting prospect for future searches [379].…”

Section: Na64mentioning

confidence: 92%

Feebly-interacting particles: FIPs 2020 workshop report

et al. 2021

View full text Add to dashboard Cite

With the establishment and maturation of the experimental programs searching for new physics with sizeable couplings at the LHC, there is an increasing interest in the broader particle and astrophysics community for exploring the physics of light and feebly-interacting particles as a paradigm complementary to a New Physics sector at the TeV scale and beyond. FIPs 2020 has been the first workshop fully dedicated to the physics of feebly-interacting particles and was held virtually from 31 August to 4 September 2020. The workshop has gathered together experts from collider, beam dump, fixed target experiments, as well as from astrophysics, axions/ALPs searches, current/future neutrino experiments, and dark matter direct detection communities to discuss progress in experimental searches and underlying theory models for FIPs physics, and to enhance the cross-fertilisation across different fields. FIPs 2020 has been complemented by the topical workshop “Physics Beyond Colliders meets theory”, held at CERN from 7 June to 9 June 2020. This document presents the summary of the talks presented at the workshops and the outcome of the subsequent discussions held immediately after. It aims to provide a clear picture of this blooming field and proposes a few recommendations for the next round of experimental results.

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Hunting down the X17 boson at the CERN SPS

Abstract: Recently, the ATOMKI experiment has reported new evidence for the excess of $$e^+e^-$$ e + e - events with a mass $$\sim $$ ∼ 17 MeV in the nuclear transitions of $$^4$$ 4 … Show more

Cited by 19 publications

References 78 publications

Signals of the QCD axion with mass of 17 MeV/c^2: nuclear transitions and light meson decays

Signals of the QCD axion with mass of 17 MeV/c^2: nuclear transitions and light meson decays

Feebly-Interacting Particles:FIPs 2020 Workshop Report

Feebly-interacting particles: FIPs 2020 workshop report

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