A
bstract
RADES (Relic Axion Detector Exploratory Setup) is a project with the goal of directly searching for axion dark matter above the 30
μ
eV scale employing custom-made microwave filters in ...magnetic dipole fields. Currently RADES is taking data at the LHC dipole of the CAST experiment. In the long term, the RADES cavities are envisioned to take data in the BabyIAXO magnet. In this article we report on the modelling, building and characterisation of an optimised microwave-filter design with alternating irises that exploits maximal coupling to axions while being scalable in length without suffering from mode-mixing. We develop the mathematical formalism and theoretical study which justifies the performance of the chosen design. We also point towards the applicability of this formalism to optimise the MADMAX dielectric haloscopes.
We study double gamma (γγ) decay nuclear matrix elements (NMEs) for a wide range of nuclei from titanium to xenon, and explore their relation to neutrinoless double-beta (0νββ) NMEs. To favor the ...comparison, we focus on double-magnetic dipole transitions in the final ββ nuclei, in particular the γγ decay of the double isobaric analog of the initial ββ state into the ground state. For the decay with equal-energy photons, our large-scale nuclear shell model results show a good linear correlation between the γγ and 0νββ NMEs. Our analysis reveals that the correlation holds for γγ transitions driven by the spin or orbital angular momentum due to the dominance of zero-coupled nucleon pairs, a feature common to 0νββ decay. Our shell-model findings point out the potential of future γγ decay measurements to constrain 0νββ NMEs, which are key to answer fundamental physics questions based on 0νββ experiments.
Solar Neutrinos Antonelli, V.; Miramonti, L.; Peña Garay, C. ...
Advances in High Energy Physics,
01/2013, Letnik:
2013
Journal Article
Recenzirano
Odprti dostop
The study of solar neutrinos has given a fundamental contribution both to astroparticle and to elementary particle physics, offering an ideal test of solar models and offering at the same time ...relevant indications on the fundamental interactions among particles. After reviewing the striking results of the last two decades, which were determinant to solve the long standing solar neutrino puzzle and refine the Standard Solar Model, we focus our attention on the more recent results in this field and on the experiments presently running or planned for the near future. The main focus at the moment is to improve the knowledge of the mass and mixing pattern and especially to study in detail the lowest energy part of the spectrum, which represents most of the solar neutrino spectrum but is still a partially unexplored realm. We discuss this research project and the way in which present and future experiments could contribute to make the theoretical framework more complete and stable, understanding the origin of some “anomalies” that seem to emerge from the data and contributing to answer some present questions, like the exact mechanism of the vacuum to matter transition and the solution of the so-called solar metallicity problem.
A
bstract
We present results of the Relic Axion Dark-Matter Exploratory Setup (RADES), a detector which is part of the CERN Axion Solar Telescope (CAST), searching for axion dark matter in the 34.67
...μ
eV mass range. A radio frequency cavity consisting of 5 sub-cavities coupled by inductive irises took physics data inside the CAST dipole magnet for the first time using this filter-like haloscope geometry. An exclusion limit with a 95% credibility level on the axion-photon coupling constant of g
aγ
≳ 4 × 10
−
13
GeV
−
1
over a mass range of 34
.
6738
μ
eV
< m
a
<
34
.
6771
μ
eV is set. This constitutes a significant improvement over the current strongest limit set by CAST at this mass and is at the same time one of the most sensitive direct searches for an axion dark matter candidate above the mass of 25
μ
eV. The results also demonstrate the feasibility of exploring a wider mass range around the value probed by CAST-RADES in this work using similar coherent resonant cavities.
We have studied the consequences of breaking the CPT symmetry in the neutrino sector, using the expected high-energy neutrino flux from distant cosmological sources such as active galaxies. For this ...purpose we have assumed three different hypotheses for the neutrino production model, characterised by the flavour fluxes at production ϕ
0
e
: ϕ
0
μ
: ϕ
0
τ
= 1 : 2 : 0, 0 : 1 : 0, and 1 : 0 : 0, and studied the theoretical and experimental expectations for the muon-neutrino flux at Earth, ϕ
μ
, and for the flavour ratios at Earth,
R
= ϕ
μ
/ϕ
e
and
S
= ϕ
τ
/ϕ
μ
. CPT violation (CPTV) has been implemented by adding an energy-independent term to the standard neutrino oscillation Hamiltonian. This introduces three new mixing angles, two new eigenvalues and three new phases, all of which have currently unknown values. We have varied the new mixing angles and eigenvalues within certain bounds, together with the parameters associated to pure standard oscillations. Our results indicate that, for the models 1 : 2 : 0 and 0 : 1 : 0, it might be possible to find large deviations of ϕ
μ
,
R
, and
S
between the cases without and with CPTV, provided the CPTV eigenvalues lie within 10
−29
− 10
−27
GeV, or above. Moreover, if CPTV exists, there are certain values of R and S that can be accounted for by up to three production models. If no CPTV were observed, we could set limits on the CPTV eigenvalues of the same order. Detection prospects calculated using IceCube suggest that for the models 1 : 2 : 0 and 0 : 1 : 0, the modifications due to CPTV are larger and more clearly separable from the standard-oscillations predictions. We conclude that IceCube is potentially able to detect CPTV but that, depending on the values of the CPTV parameters, there could be a mis-determination of the neutrino production model.
Solar neutrinos before and after Neutrino 2004 Bahcall, John N; Gonzalez-Garcia, Maria C; Peña-Garay, Carlos
The journal of high energy physics,
08/2004, Letnik:
2004, Številka:
8
Journal Article
The electromagnetic coupling axion–photon in a microwave cavity is revisited with the Boundary Integral-Resonant Mode Expansion (BI-RME) 3D technique. Such full-wave modal technique has been applied ...for the rigorous analysis of the excitation of a microwave cavity with an axion field. In this scenario, the electromagnetic field generated by the axion–photon coupling can be assumed to be driven by equivalent electrical charge and current densities. These densities have been inserted in the general BI-RME 3D equations, which express the RF electromagnetic field existing within a cavity as an integral involving the Dyadic Green’s functions of the cavity (under Coulomb gauge) as well as such densities. This method is able to take into account any arbitrary spatial and temporal variation of both magnitude and phase of the axion field. Next, we have obtained a simple network driven by the axion current source, which represents the coupling between the axion field and the resonant modes of the cavity. With this approach, it is possible to calculate the extracted and dissipated RF power as a function of frequency along a broad band and without Cauchy–Lorentz approximations, obtaining the spectrum of the electromagnetic field generated in the cavity, and dealing with modes relatively close to the axion resonant mode. Moreover, with this technique we have a complete knowledge of the signal extracted from the cavity, not only in magnitude but also in phase. This can be an interesting issue for future analysis where the axion phase is an important parameter.
We discuss constraints on the coefficient AMSW which is introduced to simulate the effect of weaker or stronger matter potential for electron neutrinos with the current and future solar neutrino ...data. The currently available solar neutrino data leads to a bound AMSW=1.47+0.54−0.42(+1.88−0.82) at 1σ (3σ) CL, which is consistent with the Standard Model prediction AMSW=1. For weaker matter potential (AMSW<1), the constraint which comes from the flat 8B neutrino spectrum is already very tight, indicating the evidence for matter effects. However for stronger matter potential (AMSW>1), the bound is milder and is dominated by the day-night asymmetry of 8B neutrino flux recently observed by Super-Kamiokande. Among the list of observables of ongoing and future solar neutrino experiments, we find that (1) an improved precision of the day-night asymmetry of 8B neutrinos, (2) precision measurements of the low-energy quasi-monoenergetic neutrinos, and (3) the detection of the upturn of the 8B neutrino spectrum at low energies are the best choices to improve the bound on AMSW.
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