Dark matter induced event rate in an Earth-based detector is predicted to show an annual modulation as a result of the Earth's orbital motion around the Sun. We searched for this modulation signature ...using the ionization signal of the DarkSide-50 liquid argon time projection chamber. No significant signature compatible with dark matter is observed in the electron recoil equivalent energy range above \(40~{\rm eV_{ee}}\), the lowest threshold ever achieved in such a search.
DEAP-3600 is a single-phase liquid argon detector aiming to directly detect weakly interacting massive particles (WIMPs), located at SNOLAB (Sudbury, Canada). After analyzing data taken during the ...first year of operation, a null result was used to place an upper bound on the WIMP-nucleon, spin-independent, isoscalar cross section. This study reinterprets this result within a nonrelativistic effective field theory framework and further examines how various possible substructures in the local dark matter halo may affect these constraints. Such substructures are hinted at by kinematic structures in the local stellar distribution observed by the Gaia satellite and other recent astronomical surveys. These include the Gaia Sausage (or Enceladus), as well as a number of distinct streams identified in recent studies. Limits are presented for the coupling strength of the effective contact interaction operators O1, O3, O5, O8, and O11, considering isoscalar, isovector, and xenonphobic scenarios, as well as the specific operators corresponding to millicharge, magnetic dipole, electric dipole, and anapole interactions. The effects of halo substructures on each of these operators are explored as well, showing that the O5 and O8 operators are particularly sensitive to the velocity distribution, even at dark matter masses above 100 GeV / c2.
A
bstract
Associated production of bottomonia and open charm hadrons in pp collisions at
s
=
7
and 8 TeV is observed using data corresponding to an integrated luminosity of 3 fb
−1
accumulated with ...the LHCb detector. The observation of five combinations, Y(1S)D
0
, Y(2S)D
0
, Y(1S)D
+
, Y(2S)D
+
and Y(1S)D
s
+
, is reported. Production crosssections are measured for Y(1S)D
0
and Y(1S)D
+
pairs in the forward region. The measured cross-sections and the differential distributions indicate the dominance of double parton scattering as the main production mechanism.
We present a novel approach for the search of dark matter in the DarkSide-50 experiment, relying on Bayesian Networks. This method incorporates the detector response model into the likelihood ...function, explicitly maintaining the connection with the quantity of interest. No assumptions about the linearity of the problem or the shape of the probability distribution functions are required, and there is no need to morph signal and background spectra as a function of nuisance parameters. By expressing the problem in terms of Bayesian Networks, we have developed an inference algorithm based on a Markov Chain Monte Carlo to calculate the posterior probability. A clever description of the detector response model in terms of parametric matrices allows us to study the impact of systematic variations of any parameter on the final results. Our approach not only provides the desired information on the parameter of interest, but also potential constraints on the response model. Our results are consistent with recent published analyses and further refine the parameters of the detector response model.
Developing sustainable software for the scientific community requires expertise in software engineering and domain science. This can be challenging due to the unique needs of scientific software, the ...insufficient resources for software engineering practices in the scientific community, and the complexity of developing for evolving scientific contexts. While open‐source software can partially address these concerns, it can introduce complicating dependencies and delay development. These issues can be reduced if scientists and software developers collaborate. We present a case study wherein scientists from the SuperNova Early Warning System collaborated with software developers from the Scalable Cyberinfrastructure for Multi‐Messenger Astrophysics project. The collaboration addressed the difficulties of open‐source software development, but presented additional risks to each team. For the scientists, there was a concern of relying on external systems and lacking control in the development process. For the developers, there was a risk in supporting a user‐group while maintaining core development. These issues were mitigated by creating a second Agile Scrum framework in parallel with the developers' ongoing Agile Scrum process. This Agile collaboration promoted communication, ensured that the scientists had an active role in development, and allowed the developers to evaluate and implement the scientists' software requirements. The collaboration provided benefits for each group: the scientists actuated their development by using an existing platform, and the developers utilized the scientists' use‐case to improve their systems. This case study suggests that scientists and software developers can avoid scientific computing issues by collaborating and that Agile Scrum methods can address emergent concerns.
Dark matter elastic scattering off nuclei can result in the excitation and ionization of the recoiling atom through the so-called Migdal effect. The energy deposition from the ionization electron ...adds to the energy deposited by the recoiling nuclear system and allows for the detection of interactions of sub-GeV/c\(^2\) mass dark matter. We present new constraints for sub-GeV/c\(^2\) dark matter using the dual-phase liquid argon time projection chamber of the DarkSide-50 experiment with an exposure of (12306 \(\pm\) 184) kg d. The analysis is based on the ionization signal alone and significantly enhances the sensitivity of DarkSide-50, enabling sensitivity to dark matter with masses down to 40 MeV/c\(^2\). Furthermore, it sets the most stringent upper limit on the spin independent dark matter nucleon cross section for masses below \(3.6\) GeV/c\(^2\).
We present a search for dark matter particles with sub-GeV/\(c^2\) masses whose interactions have final state electrons using the DarkSide-50 experiment's (12306 \(\pm\) 184) kg d low-radioactivity ...liquid argon exposure. By analyzing the ionization signals, we exclude new parameter space for the dark matter-electron cross section \(\bar{\sigma}_e\), the axioelectric coupling constant \(g_{Ae}\), and the dark photon kinetic mixing parameter \(\kappa\). We also set the first dark matter direct-detection constraints on the mixing angle \(\left|U_{e4}\right|^2\) for keV sterile neutrinos.
We report on the search for dark matter WIMPs in the mass range below 10 GeV/c\(^2\), from the analysis of the entire dataset acquired with a low-radioactivity argon target by the DarkSide-50 ...experiment at LNGS. The new analysis benefits from more accurate calibration of the detector response, improved background model, and better determination of systematic uncertainties, allowing us to accurately model the background rate and spectra down to 0.06 keV\(_{er}\). A 90% C.L. exclusion limit for the spin-independent cross section of 3 GeV/c\(^2\) mass WIMP on nucleons is set at 6\(\times\)10\(^{-43}\) cm\(^2\), about a factor 10 better than the previous DarkSide-50 limit. This analysis extends the exclusion region for spin-independent dark matter interactions below the current experimental constraints in the \(1.2, 3.6\) GeV/c\(^2\) WIMP mass range.
The CP asymmetry in the mixing of B0s and B¯0s mesons is measured in proton-proton collision data corresponding to an integrated luminosity of 3.0 fb-1, recorded by the LHCb experiment at ...center-of-mass energies of 7 and 8 TeV. Semileptonic B0s and B¯0s decays are studied in the inclusive mode D∓sμ±ν(–)μX with the D∓s mesons reconstructed in the K+K–π∓ final state. Correcting the observed charge asymmetry for detection and background effects, the CP asymmetry is found to be assl = (0.39 ± 0.26 ± 0.20)%, where the first uncertainty is statistical and the second systematic. This is the most precise measurement of assl to date. It is consistent with the prediction from the standard model and will constrain new models of particle physics.
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