Solar X-rays from Axions: Rest-Mass Dependent Signatures

The spectral shape of solar X-rays is a power law. The more active the Sun is, the less steep the distribution. This behaviour can be explained by axion regeneration to X-rays occurring ~400km deep into the photosphere. Their down-comptonization reproduces the measured spectral shape, pointing at axions with rest mass m_a~17 meV/c2, without contradicting astrophysical-laboratory limits. Directly measured soft X-ray spectra from the extremely quiet Sun during 2009 (SphinX mission), though hitherto overlooked, fitt the axion scenario.Comment: To appear in Proceedings of the 5th Patras Axion Workshop, Durham 200

Ultralow background periods in CAST Micromegas detectors and tests in the Canfranc underground laboratory

Yıldız, Süleyman Cenk (Dogus Author)Micromegas detectors have shown a low and stable background level in the CAST experiment due to their low radioactive materials, good energy resolution and spatial resolution. Since 2008, four ultralow background periods have been observed with the new microbulk detectors. During these periods, the background level reduced one order of magnitude, reaching a value around 10-7 s-1 keV-1 cm-2 between 2 and 7 keV. In all cases, the intensity of the three fluorescence lines (at 3, 6 and 8 keV) presented at the background spectrum reduced but the relative ratio remained stable. To clarify the origin of these periods and might determine the ultimate background level of these readouts, a CAST-like detector has been installed at the Canfranc Underground Laboratory. The actual level is compatible with the one measured in CAST. A new Micromegas detectors is being developped for working in CAST experiment during 2011, based on the conclusions of this work

First results of the CAST-RADES haloscope search for axions at 34.67 μeV

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 34.67μeV 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 gaγ & 4 × 10−13 GeV−1 over a mass range of 34.6738μeV < ma < 34.6771μeV 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 25μeV. 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 cavitiesWe wish to thank our colleagues at CERN, in particular Marc Thiebert from the coating lab, as well as the whole team of the CERN Central Cryogenic Laboratory for their support and advice in speci c aspects of the project. We thank Arefe Abghari for her contributions as the project's summer student during 2018. This work has been funded by the Spanish Agencia Estatal de Investigacion (AEI) and Fondo Europeo de Desarrollo Regional (FEDER) under project FPA-2016-76978-C3-2-P and PID2019-108122GB-C33, and was supported by the CERN Doctoral Studentship programme. The research leading to these results has received funding from the European Research Council and BD, JG and SAC acknowledge support through the European Research Council under grant ERC-2018-StG-802836 (AxScale project). BD also acknowledges fruitful discussions at MIAPP supported by DFG under EXC-2094 { 390783311. IGI acknowledges also support from the European Research Council (ERC) under grant ERC-2017-AdG-788781 (IAXO+ project). JR has been supported by the Ramon y Cajal Fellowship 2012-10597, the grant PGC2018-095328-B-I00(FEDER/Agencia estatal de investigaci on) and FSE-GA2017-2019-E12/7R (Gobierno de Aragón/FEDER) (MINECO/FEDER), the EU through the ITN \Elusives" H2020-MSCA-ITN-2015/674896 and the Deutsche Forschungsgemeinschaft under grant SFB-1258 as a Mercator Fellow. CPG was supported by PROMETEO II/2014/050 of Generalitat Valenciana, FPA2014-57816-P of MINECO and by the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreements 690575 and 674896. AM is supported by the European Research Council under Grant No. 742104. Part of this work was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344

Electric dipole moments and the search for new physics

Static electric dipole moments of nondegenerate systems probe mass scales for physics beyond the Standard Model well beyond those reached directly at high energy colliders. Discrimination between different physics models, however, requires complementary searches in atomic-molecular-and-optical, nuclear and particle physics. In this report, we discuss the current status and prospects in the near future for a compelling suite of such experiments, along with developments needed in the encompassing theoretical framework.Comment: Contribution to Snowmass 2021; updated with community edits and endorsement

Αναζήτηση αξιονίων μέσα από αστροφυσικές παρατηρήσεις

The present thesis has purpose the axion research (Dark Matter particles) by Astrophysical observations. The main activity has been established in CAST (Cern Axion Solar Telescope) in Geneva. In this thesis the axion detection prospects are defined in parallel with the detector's data analysis. An engineering approach is also given as main and substantial part (fluid dynamics) for the CAST physics reliability. The research is ongoing to the Dark Energy sector willing to explore the possibility of chameleons (dark energy particles) through radiation pressure.Η παρούσα εργασία έχει ως σκοπό την αναζήτηση αξιονίων (σωματιδίων Σκοτεινής Ύλης) μέσα από αστροφυσικές παρατηρήσεις. Από τις πρώτες παρατηρήσεις της ταχύτητας περιστροφής αστέρων σε σμήνη Γαλαξιών από τον Zwicky και μετά, έγινε σαφές στην επιστημονική κοινότητα πως η ύπαρξη σκοτεινής ύλης καθώς και η κατανόηση της είναι θεμελιώδους σημασίας για την Κοσμολογία. Το ποσοστό της σκοτεινής ύλης του σύμπαντος (~21%), σε σχέση με το αυτό της ύλης που παρατηρούμε (~4%), καθιστά σαφή την αναγκαιότητα για εντατική έρευνα στο πεδίο αυτό της Φυσικής. Ανάγκη δε, προκύπτει επίσης για την εξερεύνηση της σκοτεινής ενέργειας η οποία αποτελεί το υπόλοιπο ~75% του Σύμπαντος. Ένα μικρό μέρος της παρούσας έρευνας στο CERN έχει επικεντρωθεί και στην μελέτη Σκοτεινής ενέργειας καθώς, το πείραμα μέσα από το οποίο προσεγγίζεται η αναζήτηση αξιονίων (CAST – CERN Axion Solar Telescope), προσανατολίζεται συγχρόνως στην έρευνα σωματιδίων Σκοτεινής ενέργειας (χαμαιλέοντες)

Measurement of the intrinsic hadronic contamination in the NA64−e high-purity e⁺/e⁻ beam at CERN

We present the measurement of the intrinsic hadronic contamination at the CERN SPS H4 beamline configured to transport electrons and positrons at 100 GeV/c. The analysis, performed using data collected by the NA64-e experiment in 2022, is based on calorimetric measurements, exploiting the different interaction mechanisms of electrons and hadrons in the NA64 detector. We determined the contamination by comparing the results obtained using the nominal electron/positron beamline configuration with those from a dedicated setup, in which only hadrons impinged on the detector. We also obtained an estimate of the relative protons, anti-protons and pions yield by exploiting the different absorption probabilities of these particles in matter. We cross-checked our results with a dedicated Monte Carlo simulation for the hadron production at the primary T2 target, finding a good agreement with the experimental measurements.ISSN:0168-9002ISSN:1872-957

Search for pseudoscalar bosons decaying into e+e- pairs in the NA64 experiment at the CERN SPS

We report the results of a search for a light pseudoscalar particle a that couples to electrons and decays to e+e- performed using the high-energy CERN SPS H4 electron beam. If such light pseudoscalar exists, it could explain the ATOMKI anomaly (an excess of e+e- pairs in the nuclear transitions of Be8 and He4 nuclei at the invariant mass ≃17 MeV observed by the experiment at the 5 MV Van de Graaff accelerator at ATOMKI, Hungary). We used the NA64 data collected in the "visible mode"configuration with a total statistics corresponding to 8.4×1010 electrons on target (EOT) in 2017 and 2018. In order to increase sensitivity to small coupling parameter ϵ we also used the data collected in 2016-2018 in the "invisible mode"configuration of NA64 with a total statistics corresponding to 2.84×1011 EOT. The background and efficiency estimates for these two configurations were retained from our previous analyses searching for light vector bosons and axionlike particles (ALP) (the latter were assumed to couple predominantly to γ). In this work we recalculate the signal yields, which are different due to different cross section and lifetime of a pseudoscalar particle a, and perform a new statistical analysis. As a result, the region of the two dimensional parameter space ma-ϵ in the mass range from 1 to 17.1 MeV is excluded. At the mass of the central value of the ATOMKI anomaly (the first result obtained on the beryllium nucleus, 16.7 MeV) the values of ϵ in the range 2.1×10-4<ϵ<3.2×10-4 are excluded.ISSN:1550-7998ISSN:0556-2821ISSN:1550-236

Search for a light Z′ in the Lμ-Lτ scenario with the NA64-e experiment at CERN

The extension of Standard Model made by inclusion of additional U(1) gauge Lμ-Lτ symmetry can explain the difference between the measured and the predicted value of the muon magnetic moment and solve the tension in B meson decays. This model predicts the existence of a new, light Z′ vector boson, predominantly coupled to second and third generation leptons, whose interaction with electrons is due to a loop mechanism involving muons and taus. In this work, we present a rigorous evaluation of the upper limits in the Z′ parameter space, obtained from the analysis of the data collected by the NA64-e experiment at CERN SPS, that performed a search for light dark matter with 2.84×1011 electrons impinging with 100 GeV on an active thick target. The resulting limits touch the muon g-2 preferred band for values of the Z′ mass of order of 1 MeV, while the sensitivity projections for the future high-statistics NA64-e runs demonstrate the power of the electrons/positron beam approach in this theoretical scenario.ISSN:1550-7998ISSN:0556-2821ISSN:1550-236

Search for a New B-L Z′ Gauge Boson with the NA64 Experiment at CERN

A search for a new Z′ gauge boson associated with (un)broken B-L symmetry in the keV-GeV mass range is carried out for the first time using the missing-energy technique in the NA64 experiment at the CERN SPS. From the analysis of the data with 3.22×1011 electrons on target collected during 2016-2021 runs, no signal events were found. This allows us to derive new constraints on the Z′-e coupling strength, which, for the mass range 0.3mZ′ 100 MeV, are more stringent compared to those obtained from the neutrino-electron scattering data.ISSN:0031-9007ISSN:1079-711