Extensions of superscaling from relativistic mean field theory : the SuSAv2 model

We present a systematic analysis of the quasielastic scaling functions computed within the relativistic mean field (RMF) theory and we propose an extension of the superscaling approach (SuSA) model based on these results. The main aim of this work is to develop a realistic and accurate phenomenological model (SuSAv2), which incorporates the different RMF effects in the longitudinal and transverse nuclear responses, as well as in the isovector and isoscalar channels. This provides a complete set of reference scaling functions to describe in a consistent way both (e, e') processes and the neutrino/antineutrino-nucleus reactions in the quasielastic region. A comparison of the model predictions with electron and neutrino scattering data is presented

QCD and strongly coupled gauge theories : challenges and perspectives

We highlight the progress, current status, and open challenges of QCD-driven physics, in theory and in experiment. We discuss how the strong interaction is intimately connected to a broad sweep of physical problems, in settings ranging from astrophysics and cosmology to strongly coupled, complex systems in particle and condensed-matter physics, as well as to searches for physics beyond the Standard Model. We also discuss how success in describing the strong interaction impacts other fields, and, in turn, how such subjects can impact studies of the strong interaction. In the course of the work we offer a perspective on the many research streams which flow into and out of QCD, as well as a vision for future developments.Peer reviewe

Research and development for near detector systems towards long term evolution of ultra-precise long-baseline neutrino experiments: Input from the CENF-ND Forum to the 2020 Update of the European Strategy for Particle Physics

With the discovery of non-zero value of θ13 mixing angle, the next generation of longbaseline neutrino (LBN) experiments offers the possibility of obtaining statistically significant samples of muon and electron neutrinos and anti-neutrinos with large oscillation effects. In this document we intend to highlight the importance of Near Detector facilities in LBN experiments to both constrain the systematic uncertainties affecting oscillation analyses but also to perform, thanks to their close location, measurements of broad benefit for LBN physics goals. A strong European contribution to these efforts is possible

Diffuse supernova neutrino background search at Super-Kamiokande

We have conducted a new search for the diffuse supernova neutrino background (DSNB) flux at Super-Kamiokande (SK), with a 22.5×2970-kton·day exposure from its fourth operational phase IV. With the new analysis we improve on the existing background reduction techniques and systematic uncertainties and take advantage of an improved neutron tagging algorithm to lower the energy threshold compared to the previous phases of SK. This allows for setting the world's most stringent upper limit on the extraterrestrial ν¯e flux, for neutrino energies below 31.3 MeV. The SK-IV results are combined with the ones from the first three phases of SK to perform a joint analysis using 22.5×5823 kton·days of data. This analysis has the world's best sensitivity to the DSNB ν¯e flux, comparable to the predictions from various models. For neutrino energies larger than 17.3 MeV, the new combined 90% CL upper limits on the DSNB ν¯e flux lie around 2.7 cm-2·sec-1, strongly disfavoring the most optimistic predictions. Finally, potentialities of the gadolinium phase of SK and the future Hyper-Kamiokande experiment are discussed

First gadolinium loading to Super-Kamiokande

In order to improve Super-Kamiokande's neutron detection efficiency and to thereby increase its sensitivity to the diffuse supernova neutrino background flux, 13 tons of Gd2(SO4)3⋅8H2O (gadolinium sulfate octahydrate) was dissolved into the detector's otherwise ultrapure water from July 14 to August 17, 2020, marking the start of the SK-Gd phase of operations. During the loading, water was continuously recirculated at a rate of 60 m3/h, extracting water from the top of the detector and mixing it with concentrated Gd2(SO4)3⋅8H2O solution to create a 0.02% solution of the Gd compound before injecting it into the bottom of the detector. A clear boundary between the Gd-loaded and pure water was maintained through the loading, enabling monitoring of the loading itself and the spatial uniformity of the Gd concentration over the 35 days it took to reach the top of the detector. During the subsequent commissioning the recirculation rate was increased to 120 m3/h, resulting in a constant and uniform distribution of Gd throughout the detector and water transparency equivalent to that of previous pure-water operation periods. Using an Am–Be neutron calibration source the mean neutron capture time was measured to be 115±1 μs, which corresponds to a Gd concentration of 111±2 ppm, as expected for this level of Gd loading. This paper describes changes made to the water circulation system for this detector upgrade, the Gd loading procedure, detector commissioning, and the first neutron calibration measurements in SK-Gd

Search for neutrinos in coincidence with gravitational wave events from the LIGO–Virgo O3a observing run with the Super-Kamiokande detector

The Super-Kamiokande detector can be used to search for neutrinos in time coincidence with gravitational waves detected by the LIGO–Virgo Collaboration (LVC). Both low-energy (7–100 MeV) and high-energy (0.1–105 GeV) samples were analyzed in order to cover a very wide neutrino spectrum. Follow-ups of 36 (out of 39) gravitational waves reported in the GWTC-2 catalog were examined; no significant excess above the background was observed, with 10 (24) observed neutrinos compared with 4.8 (25.0) expected events in the high-energy (low-energy) samples. A statistical approach was used to compute the significance of potential coincidences. For each observation, p-values were estimated using neutrino direction and LVC sky map; the most significant event (GW190602_175927) is associated with a post-trial p-value of 7.8% (1.4σ). Additionally, flux limits were computed independently for each sample and by combining the samples. The energy emitted as neutrinos by the identified gravitational wave sources was constrained, both for given flavors and for all flavors assuming equipartition between the different flavors, independently for each trigger and by combining sources of the same nature