Two-neutrino double electron capture on 124Xe based on an effective theory and the nuclear shell model

Pérez, E. A. Coello; Menéndez, J. Fernández; Schwenk, A.

doi:10.1016/j.physletb.2019.134885

Cited by 16 publications

(13 citation statements)

References 76 publications

(136 reference statements)

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“…Its double-K-electron capture (2νECEC) has recently been measured with the XENON1T Dark Matter detector [13]. At T 2νKK 1/2 = (1.8 ± 0.5 stat ± 0.1 sys ) × 10 22 year the measurement agrees well with recent theoretical predictions [14][15][16]. In this decay, the measurable signal is constituted by the atomic deexcitation cascade of X-rays and Auger electrons that occurs when the vacancies of the captured elec-trons are refilled.…”

Section: Introductionsupporting

confidence: 77%

“…Therefore, we give a range of PSF values. For predicting the half-lives of the decay modes 2νECβ + and 2νβ + β + we use the central value of this range as the most probable PSF value and half of this range as the uncertainty (16) we choose to use these in our calculations. The resulting halflife estimates for 124 Xe are listed under "Constraints 2" in Table 3.…”

Section: Neutrinoless Decaysmentioning

confidence: 99%

“…The second comes from the interacting boson model (IBM) [24,37]. The third set is based on nuclear shell model (NSM) calculations as performed for the two-neutrino case [16] and is limited by lower and upper values of the full shell model similar to normal neutrinoless double-β decay as shown in [38,39]. Both the QRPA and NSM calculations provided good predictions of T 1/2 for 2νECEC while there were no 2ν-predictions for IBM.…”

Section: Neutrinoless Decaysmentioning

confidence: 99%

“…The NME-range for QRPA stems from the smallest and largest NME value for g A = 1.25 under the assumption of different bases and short-range correlations. For the 0νECβ + and the 0νβ + β + QRPA [14], NSM (calculated in [40] as in [16]), and IBM [37] NMEs were considered. The range of NMEs for QRPA and the value for IBM are obtained as above.…”

Section: Neutrinoless Decaysmentioning

confidence: 99%

“…Scenarios three and four are based on constraint 2, using the KamLAND Zen effective neutrino mass limits from Eq. (16). The results are shown as a function of exposure in Fig.…”

Section: Sensitivitymentioning

confidence: 99%

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Detection prospects for the second-order weak decays of $$^{124}$$Xe in multi-tonne xenon time projection chambers

et al. 2020

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We investigate the detection prospects for two-neutrino and neutrinoless second-order weak decays of $$^{124}{\mathrm{Xe}}$$ 124 Xe – double-electron capture ($$0/2\upnu \text {ECEC}$$ 0 / 2 ν ECEC ), electron capture with positron emission ($$0/2\upnu \text {EC}\upbeta ^+$$ 0 / 2 ν EC β + ) and double-positron emission ($$0/2\upnu \upbeta ^+\upbeta ^+$$ 0 / 2 ν β + β + ) – in multi-tonne xenon time projection chambers. We simulate the decays in a liquid xenon medium and develop a reconstruction algorithm which uses the multi-particle coincidence in these decays to separate signal from background. This is used to compute the expected detection efficiencies as a function of position resolution and energy threshold for planned experiments. In addition, we consider an exhaustive list of possible background sources and find that they are either negligible in rate or can be greatly reduced using our topological reconstruction criteria. In particular, we draw two conclusions: First, with a theoretical half-life of $$T_{1/2}^{2\upnu \text {EC}\upbeta ^+} = (1.7 \pm 0.6)\cdot 10^{23}\,\text {year}$$ T 1 / 2 2 ν EC β + = ( 1.7 ± 0.6 ) · 10 23 year , the $$2\upnu \text {EC}\upbeta ^{+}$$ 2 ν EC β + decay of $$^{124}$$ 124 Xe will likely be detected in upcoming Dark Matter experiments (e.g. XENONnT or LZ), and their major background will be $$\upgamma $$ γ -rays from detector construction materials. Second, searches for the $$0\upnu \text {EC}\upbeta ^+$$ 0 ν EC β + decay mode will likely be background-free, and new parameter space may be within reach. To this end we investigate two different scenarios of existing experimental constraints on the effective neutrino mass. The necessary 500 kg-year exposure of $$^{124}$$ 124 Xe could be achieved by the baseline design of the DARWIN observatory, or by extracting and using the $$^{124}$$ 124 Xe from the tailings of the nEXO experiment. We demonstrate how a combination of $$^{124}$$ 124 Xe results with those from $$0\upnu \upbeta ^-\upbeta ^-$$ 0 ν β - β - searches in $$^{136}$$ 136 Xe could help to identify the neutrinoless decay mechanism.

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Section: Introductionsupporting

confidence: 77%

Section: Neutrinoless Decaysmentioning

confidence: 99%

Section: Neutrinoless Decaysmentioning

confidence: 99%

Section: Neutrinoless Decaysmentioning

confidence: 99%

“…Scenarios three and four are based on constraint 2, using the KamLAND Zen effective neutrino mass limits from Eq. (16). The results are shown as a function of exposure in Fig.…”

Section: Sensitivitymentioning

confidence: 99%

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Detection prospects for the second-order weak decays of $$^{124}$$Xe in multi-tonne xenon time projection chambers

et al. 2020

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Sensitivity of the NEXT experiment to Xe-124 double electron capture

Martínez-Lema¹,

Martínez-Vara²,

Sorel³

et al. 2021

J. High Energ. Phys.

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Double electron capture by proton-rich nuclei is a second-order nuclear process analogous to double beta decay. Despite their similarities, the decay signature is quite different, potentially providing a new channel to measure the hypothesized neutrinoless mode of these decays. The Standard-Model-allowed two-neutrino double electron capture (2νEC EC) has been predicted for a number of isotopes, but only observed in 78Kr, 130Ba and, recently, 124Xe. The sensitivity to this decay establishes a benchmark for the ultimate experimental goal, namely the potential to discover also the lepton-number-violating neutrinoless version of this process, 0νEC EC. Here we report on the current sensitivity of the NEXT-White detector to 124Xe 2νEC EC and on the extrapolation to NEXT-100. Using simulated data for the 2νEC EC signal and real data from NEXT-White operated with 124Xe-depleted gas as background, we define an optimal event selection that maximizes the NEXT-White sensitivity. We estimate that, for NEXT-100 operated with xenon gas isotopically enriched with 1 kg of 124Xe and for a 5-year run, a sensitivity to the 2νEC EC half-life of 6 × 1022 y (at 90% confidence level) or better can be reached.

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The search for neutrinoless double-beta decay

Gómez-Cadenas,

Martín-Albo,

Menéndez

et al. 2024

Riv. Nuovo Cim.

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Neutrinos are the only particles in the Standard Model that could be Majorana fermions, that is, completely neutral fermions that are their own antiparticles. The most sensitive known experimental method to verify whether neutrinos are Majorana particles is the search for neutrinoless double-beta decay. The last 2 decades have witnessed the development of a vigorous program of neutrinoless double-beta decay experiments, spanning several isotopes and developing different strategies to handle the backgrounds masking a possible signal. In addition, remarkable progress has been made in the understanding of the nuclear matrix elements of neutrinoless double-beta decay, thus reducing a substantial part of the theoretical uncertainties affecting the particle–physics interpretation of the process. On the other hand, the negative results by several experiments, combined with the hints that the neutrino mass ordering could be normal, may imply very long lifetimes for the neutrinoless double-beta decay process. In this report, we review the main aspects of such process, the recent progress on theoretical ideas and the experimental state of the art. We then consider the experimental challenges to be addressed to increase the sensitivity to detect the process in the likely case that lifetimes are much longer than currently explored, and discuss a selection of the most promising experimental efforts.

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Two-neutrino double electron capture on 124Xe based on an effective theory and the nuclear shell model

Cited by 16 publications

References 76 publications

Detection prospects for the second-order weak decays of $$^{124}$$Xe in multi-tonne xenon time projection chambers

Detection prospects for the second-order weak decays of $$^{124}$$Xe in multi-tonne xenon time projection chambers

Sensitivity of the NEXT experiment to Xe-124 double electron capture

The search for neutrinoless double-beta decay

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