On-site background measurements for the J-PARC E56 experiment: A search for the sterile neutrino at J-PARC MLF

Ajimura, S.; Bezerra, T. J. C.; Chauveau, E.; Enomoto, Takahiro; Furuta, H.; Harada, Masahide; Hasegawa, S.; Hiraiwa, T.; Igarashi, Y.; Iwai, E.; Maruyama, T.; Meigo, Shin-ichiro; Nakano, T.; Niiyama, M.; Nishikawa, K.; Nomachi, M.; Ohta, R.; Sakai, Hisakazu; Sakai, Kazuhiro; Sakamoto, Shinichi; Shima, T.; Suekane, F.; Suzuki, Shoji; Suzuya, Kentaro; Tauchi, K.

doi:10.1093/ptep/ptv078

Cited by 16 publications

(19 citation statements)

References 12 publications

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“…the correlated part could be partly understood as a one-sigma exchange potential, but all other contributions will appear in many-different partial waves. They should, eventually, help to understand more precise data on non-mesonic weak decay, in particular from the experiments E18 [25] (on 12 Λ C) and E22 [26] (on A = 4 hypernuclei) in J-PARC. From a practical point of view the potentials obtained neglecting the baryonic mass differences should be accurate and fast enough to be amenable for state-of-the-art few-body computations.…”

Section: Discussionmentioning

confidence: 99%

Next-to-leading order effective field theory Λ N → NN potential in coordinate space

Pérez-Obiol¹,

Entem²,

Juliá-Dı́az³

et al. 2016

Nuclear Physics A

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The potential in coordinate space for the ΛN → N N weak transition, which drives the weak decay of most hypernuclei, is derived within the effective field theory formalism up to next-to-leading order. This coordinate space potential allows us to discuss how the different contributions to the potential add up at the different scales. Explicit expressions are given for each two-pion-exchange diagram contributing to the interaction. The potential is also reorganized into spin and isospin operators, and the coefficient for each operator is given in analytical form and represented in coordinate space. The relevance of explicitly including the mass differences among the baryons appearing in the two-pion-exchange diagrams is also discussed in detail.Theoretical studies of the non-mesonic weak decay amplitude were first based on one-meson-exchange (OME) models (see for example Refs. [8,9,10,11]). These models describe the long range part of the interaction through the exchange of one pion, and the shorter ranges through the exchange of heavier mesons, the η, ρ, ω, K and K * , which allow to mediate the strangeness exchange transition through weak vertices like N N K or ΛN η. With the advent of the more systematic effective field theory (EFT) formalism, and in particular with its successful description of the NN strong interaction [12,13], first steps were done in applying EFT also to the description of the non-mesonic weak decay. The EFT for the ΛN → N N potential was first studied at leading order (LO) in Refs. [14,15,16]. In Ref.[17] the EFT was further developed up to next-to-leading order (NLO), including all the possible two-pion-exchange (TPE) diagrams contributing to the transition. The potential was calculated in momentum space, and expressions in terms of master integrals were given separately for each diagram.In the present work we provide all the needed expressions in coordinate space. The different contributions to the transition potential are written in terms of 20 operational structures. Notably, a simplified version of the transition potential, obtained neglecting the baryonic mass differences of virtual baryons, provides a compelling description of the full potential. These should be readily useful for ab-initio few-body computations of the weak decay of hypernuclei [18,19,20,21].The manuscript is organized in the following way. In the beginning of Sect. 2 we review the EFT formalism used to calculate the non-mesonic weak transition. The EFT potentials up to NLO are derived in coordinate space and presented in terms of spin and isospin operators instead of diagrams. This allows us to plot for each operator the LO and the NLO potentials, and thus evaluate the magnitude of the two-pion exchanges in the ΛN → N N amplitude. The comparison is provided for each operational structure appearing in the transition potential. For the NLO, we derive approximate potentials neglecting the mass difference among the virtual baryons and compare them with the exact ones. In Sect. 3 we discuss the properties of the obtained...

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Section: Discussionmentioning

confidence: 99%

Next-to-leading order effective field theory Λ N → NN potential in coordinate space

Pérez-Obiol¹,

Entem²,

Juliá-Dı́az³

et al. 2016

Nuclear Physics A

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“…While many of the low-energy, high-intensity frontier experiments possibly would enjoy the advantage of a combination of energy and timing cuts in terms of dark matter searches, we particularly focus on the COHERENT [15,17,18], JSNS 2 [19][20][21], and CCM [22][23][24] experiments to apply our search techniques for. They are equipped with an O(1 GeV) beam delivering ∼ 10 22 − 10 23 protons-on-target (POT) per year, hence producing dark matter particles copiously.…”

Section: Jhep01(2022)144mentioning

confidence: 99%

Searching for dark matter signals in timing spectra at neutrino experiments

Dutta

Kim

Liao

et al. 2022

J. High Energ. Phys.

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The sensitivity to dark matter signals at neutrino experiments is fundamentally challenged by the neutrino rates, as they leave similar signatures in their detectors. As a way to improve the signal sensitivity, we investigate a dark matter search strategy which utilizes the timing and energy spectra to discriminate dark matter from neutrino signals at low-energy, pulsed-beam neutrino experiments. This strategy was proposed in our companion paper Phys. Rev. Lett.124 (2020) 121802 [1], which we apply to potential searches at COHERENT, JSNS2, and CCM. These experiments are not only sources of neutrinos but also high intensity sources of photons. The dark matter candidate of interest comes from the relatively prompt decay of a dark sector gauge boson which may replace a Standard-Model photon, so the delayed neutrino events can be suppressed by keeping prompt events only. Furthermore, prompt neutrino events can be rejected by a cut in recoil energy spectra, as their incoming energy is relatively small and bounded from above while dark matter may deposit a sizable energy beyond it. We apply the search strategy of imposing a combination of energy and timing cuts to the existing CsI and LAr data of the COHERENT experiment as concrete examples, and report a mild excess beyond known backgrounds. We then investigate the expected sensitivity reaches to dark matter signals in our benchmark experiments.

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“…II: beam-on backgrounds including beam-induced gamma rays and neutrons and neu- trinos produced in the target, and steady-state backgrounds coming from cosmic rays and environmental gamma rays. Detailed measurements of many of these backgrounds have been performed using a 500 kg plastic scintillator detector placed on the third floor of the MLF [37]. Above the 20 MeV threshold used for this analysis, the dominant backgrounds come from neutrino interactions in the detector and cosmic gamma rays which can fake the DM-induced electron scattering or decay signals.…”

Section: Backgroundsmentioning

confidence: 99%

“…Due to the coarseness of the energy bins available to generate cosmic rays in CRY, a triple exponential fit to the resulting cosmic ray spectrum was used. This follows the treatment used to model the measured cosmic ray gamma background below 100 MeV on the MLF third floor [37], but adds an additional exponential to account for the rate at high energies. Finally, due to the extremely high cosmic background event rate even after the veto and timing cuts, we assume that an additional 7 cm of lead shielding is added around the detector to further attenuate the cosmic gamma ray background.…”

Section: Backgroundsmentioning

confidence: 99%

Signatures of pseudo-Dirac dark matter at high-intensity neutrino experiments

et al. 2018

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We (re)consider the sensitivity of past (LSND) and future (JSNS 2 ) beam dump neutrino experiments to two models of MeV-scale pseudo-Dirac dark matter. Both LSND and JSNS 2 are close (24-30 m) to intense sources of light neutral mesons which may decay to dark matter via interactions involving a light mediator or dipole operators. The dark matter can then scatter or decay inside of the nearby detector. We show that the higher beam energy of JSNS 2 and resulting η production can improve on the reach of LSND for light-mediator models with dark matter masses greater than mπ/2. Further, we find that both existing LSND and future JSNS 2 measurements can severely constrain the viable parameter space for a recently-proposed model of dipole dark matter which could explain the 3.5 keV excess reported in observations of stacked galaxy clusters and the Galactic Center.

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On-site background measurements for the J-PARC E56 experiment: A search for the sterile neutrino at J-PARC MLF

Cited by 16 publications

References 12 publications

Next-to-leading order effective field theory Λ N → NN potential in coordinate space

Next-to-leading order effective field theory Λ N → NN potential in coordinate space

Searching for dark matter signals in timing spectra at neutrino experiments

Signatures of pseudo-Dirac dark matter at high-intensity neutrino experiments

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