Rubin-LSST

Abstract:

A liquid scintillator consisting of linear alkylbenzene as the solvent and 2,5-diphenyloxazole as the fluor was developed for the SNO+ experiment. This mixture was chosen as it is compatible with acrylic and has a competitive light yield to pre-existing liquid scintillators while conferring other advantages including longer attenuation lengths, superior safety characteristics, chemical simplicity, ease of handling, and logistical availability. Its properties have been extensively characterized and are presented here. This liquid scintillator is now used in several neutrino physics experiments in addition to SNO+.

Abstract:

Abstract A search for a heavy neutral Higgs boson, A , decaying into a Z boson and another heavy Higgs boson, H , is performed using a data sample corresponding to an integrated luminosity of 139 fb $$^{-1}$$ -1 from proton–proton collisions at $$\sqrt{s} = 13$$ s=13 $$\text {TeV}$$ TeV recorded by the ATLAS detector at the LHC. The search considers the Z boson decaying into electrons or muons and the H boson into a pair of b -quarks or W bosons. The mass range considered is 230–800 $$\text {GeV}$$ GeV for the A boson and 130–700 $$\text {GeV}$$ GeV for the H boson. The data are in good agreement with the background predicted by the Standard Model, and therefore 95% confidence-level upper limits for $$\sigma \times B(A\rightarrow ZH)\times B(H\rightarrow bb \; \text {or} \; H \rightarrow WW)$$ σ×B(A→ZH)×B(H→bborH→WW) are set. The upper limits are in the range 0.0062–0.380 pb for the $$H\rightarrow bb$$ H→bb channel and in the range 0.023–8.9 pb for the $$H\rightarrow WW$$ H→WW channel. An interpretation of the results in the context of two-Higgs-doublet models is also given.

Abstract:

We use new Hubble Space Telescope (HST) images of nine Green Pea galaxies (GPGs) to study their resolved structure and color. The choice of filters, F555W and F850LP, together with the redshift of the galaxies (z ~ 0.25), minimizes the contribution of the nebular [O iii] and Hα emission lines to the broadband images. While these galaxies are typically very blue in color, our analysis reveals that it is only the dominant stellar clusters that are blue. Each GPG does clearly show the presence of at least one bright and compact star-forming region, but these are invariably superimposed on a more extended and lower surface brightness emission. Moreover, the colors of the star-forming regions are on average bluer than those of the diffuse emission, reaching up to 0.6 magnitudes bluer. Assuming that the diffuse and compact components have constant and single-burst star formation histories, respectively, the observed colors imply that the diffuse components (possibly the host galaxy of the star formation episode) have, on average, old stellar ages (>1 Gyr), while the star clusters are younger than 500 Myr. While a redder stellar component is perhaps the most plausible explanation for these results, the limitations of our current data set lead us to examine possible alternative mechanisms, particularly recombination emission processes, which are unusually prominent in systems with such strong line emission. With the available data, however, it is not possible to distinguish between these two interpretations. A substantial presence of old stars would indicate that the mechanisms allowing large escape fractions in these local galaxies may be different from those at play during the reionization epoch.

Abstract:

The deep underground neutrino experiment (DUNE), a 40-kton underground liquid argon time projection chamber experiment, will be sensitive to the electron-neutrino flavor component of the burst of neutrinos expected from the next Galactic core-collapse supernova. Such an observation will bring unique insight into the astrophysics of core collapse as well as into the properties of neutrinos. The general capabilities of DUNE for neutrino detection in the relevant few- to few-tens-of-MeV neutrino energy range will be described. As an example, DUNE’s ability to constrain the νe spectral parameters of the neutrino burst will be considered.