The QCD axion is a leading dark matter candidate that emerges as part of the solution to the strong-CP problem in the Standard Model. The coupling of the axion to photons is the most common ...experimental probe, but much parameter space remains unexplored. The coupling of the QCD axion to the Standard Model scales linearly with the axion mass; therefore, the highly motivated region 0.4–120 neV, corresponding to a GUT-scale axion, is particularly difficult to reach. This paper presents the design requirements for a definitive search for GUT-scale axions and reviews the technological advances needed to enable this program.
The manipulation of quantum states of light
holds the potential to enhance searches for fundamental physics. Only recently has the maturation of quantum squeezing technology coincided with the ...emergence of fundamental physics searches that are limited by quantum uncertainty
. In particular, the quantum chromodynamics axion provides a possible solution to two of the greatest outstanding problems in fundamental physics: the strong-CP (charge-parity) problem of quantum chromodynamics
and the unknown nature of dark matter
. In dark matter axion searches, quantum uncertainty manifests as a fundamental noise source, limiting the measurement of the quadrature observables used for detection. Few dark matter searches have approached this limit
, and until now none has exceeded it. Here we use vacuum squeezing to circumvent the quantum limit in a search for dark matter. By preparing a microwave-frequency electromagnetic field in a squeezed state and near-noiselessly reading out only the squeezed quadrature
, we double the search rate for axions over a mass range favoured by some recent theoretical projections
. We find no evidence of dark matter within the axion rest energy windows of 16.96-17.12 and 17.14-17.28 microelectronvolts. Breaking through the quantum limit invites an era of fundamental physics searches in which noise reduction techniques yield unbounded benefit compared with the diminishing returns of approaching the quantum limit.
Neutrinoless double beta decay (0νββ) processes sample a wide range of intermediate forbidden nuclear transitions, which may be impacted by quenching of the axial vector coupling constant (gA/gV), ...the uncertainty of which plays a pivotal role in determining the sensitivity reach of 0νββ experiments. Here we present measurements performed on a high-resolution LiInSe2 bolometer in a “source = detector” configuration to measure the spectral shape of the fourfold forbidden β decay of 115In . The value of gA/gV is determined by comparing the spectral shape of theoretical predictions to the experimental β spectrum taking into account various simulated background components as well as a variety of detector effects. We find evidence of quenching of gA/gV at >5 σ with a model-dependent quenching factor of 0.655 ± 0.002 as compared to the free-nucleon value for the interacting shell model. We also measured the 115In half-life to be 5.18 ± 0.06(stat) $^{+0.005}_{- 0.015}$(sys) x 1014 yr within the interacting shell model framework. This Letter demonstrates the power of the bolometeric technique to perform precision nuclear physics single-β decay measurements, which along with improved nuclear modeling can help reduce the uncertainties in the calculation of several decay nuclear matrix elements including those used in 0νββ sensitivity calculations.
CUPID-Mo is a bolometric experiment to search for neutrinoless double-beta decay (
0
ν
β
β
) of
100
Mo
. In this article, we detail the CUPID-Mo detector concept, assembly and installation in the ...Modane underground laboratory, providing results from the first datasets. The CUPID-Mo detector consists of an array of 20
100
Mo
-enriched 0.2 kg
Li
2
MoO
4
crystals operated as scintillating bolometers at
∼
20
mK
. The
Li
2
MoO
4
crystals are complemented by 20 thin Ge optical bolometers to reject
α
events by the simultaneous detection of heat and scintillation light. We observe a good detector uniformity and an excellent energy resolution of 5.3 keV (6.5 keV) FWHM at 2615 keV, in calibration (physics) data. Light collection ensures the rejection of
α
particles at a level much higher than 99.9% – with equally high acceptance for
γ
/
β
events – in the region of interest for
100
Mo
0
ν
β
β
. We present limits on the crystals’ radiopurity:
≤
3
μ
Bq/kg
of
226
Ra
and
≤
2
μ
Bq/kg
of
232
Th
. We discuss the science reach of CUPID-Mo, which can set the most stringent half-life limit on the
100
Mo
0
ν
β
β
decay in half-a-year’s livetime. The achieved results show that CUPID-Mo is a successful demonstrator of the technology developed by the LUMINEU project and subsequently selected for the CUPID experiment, a proposed follow-up of CUORE, the currently running first tonne-scale bolometric
0
ν
β
β
experiment.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
A novel search technique for ultralight dark matter has been developed and initially carried out over a limited range of frequency in L-band, utilizing the recent Breakthrough Listen public ...data release of three years of observation with the Green Bank Telescope. The search concept depends only on the assumption of decay or annihilation of virialized dark matter leading to a quasi-monochromatic radio line, and additionally that the frequency and intensity of the line be consistent with very general expected properties of the phase space of our Milky Way halo. Specifically, the search selects for a line which exhibits a Doppler shift with position according to the solar motion through a static galactic halo, and similarly varies in intensity with position with respect to the halo profile. The analysis of the full L-, S-, C- and X-band dataset by this method is currently underway.
Abstract
A novel search technique for ultralight dark matter has been developed and carried out over a narrow range in the
L
band, utilizing the recent Breakthrough Listen public data release of ...three years of observation with the Green Bank Telescope. The search concept depends only on the assumption of decay or annihilation of virialized dark matter to a quasimonochromatic radio line, and additionally that the frequency and intensity of the line be consistent with most general properties expected of the phase space of our Milky Way halo. Specifically, the search selects for a line that exhibits a Doppler shift with position according to the solar motion through a static Galactic halo and similarly varies in intensity with the position with respect to the Galactic center. Over the frequency range 1.73–1.83 GHz, radiative annihilation of dark matter is excluded above 〈
σ
v
〉 = 1.2 × 10
−47
cm
3
s
−1
and for decay above
λ
= 4.1 × 10
−35
s
−1
. The analysis of the full Breakthrough Listen GBT data set by this method (25,000 spectra, 1.1-11.6 GHz) is currently underway.
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