Search for Nucleon and Dinucleon Decays with an Invisible Particle and a Charged Lepton in the Final State at the Super-Kamiokande Experiment

Artículo escrito por muchos autores, sólo se referencian el primero, los autores que firman como Universidad Autónoma de Madrid y el grupo de colaboración en el caso de que aparezca en el artículoSearch results for nucleon decays p→e+X, p→μ+X, n→νγ (where X is an invisible, massless particle) as well as dinucleon decays np→e+ν, np→μ+ν, and np→τ+ν in the Super-Kamiokande experiment are presented. Using single-ring data from an exposure of 273.4 kton·yr, a search for these decays yields a result consistent with no signal. Accordingly, lower limits on the partial lifetimes of τp→e+X>7.9×1032yr, τp→μ+X>4.1×1032yr, τn→νγ>5.5×1032yr, τnp→e+ν>2.6×1032yr, τnp→μ+ν>2.2×1032yr, and τnp→τ+ν>2.9×1031yr at a 90% confidence level are obtained. Some of these searches are novelThe Super- Kamiokande experiment was built and has been operated with funding from the Japanese Ministry of Education, Culture, Sports, Science and Technology, the U.S. Department of Energy, and the U.S. National Science Foundatio

Spacial and temporal dynamics of the volume fraction of the colloidal particles inside a drying sessile drop

Using lubrication theory, drying processes of sessile colloidal droplets on a solid substrate are studied. A simple model is proposed to describe temporal dynamics both the shape of the drop and the volume fraction of the colloidal particles inside the drop. The concentration dependence of the viscosity is taken into account. It is shown that the final shapes of the drops depend on both the initial volume fraction of the colloidal particles and the capillary number. The results of our simulations are in a reasonable agreement with the published experimental data. The computations for the drops of aqueous solution of human serum albumin (HSA) are presented.Comment: Submitted to EPJE, 7 pages, 8 figure

Snowmass 2021 White Paper: Cosmogenic Dark Matter and Exotic Particle Searches in Neutrino Experiments

The signals from outer space and their detection have been playing animportant role in particle physics, especially in discoveries of and searchesfor physics beyond the Standard Model (BSM); beyond the evidence of dark matter(DM), for example, the neutrinos produced from the dark matter annihilation isimportant for the indirect DM searches. Moreover, a wide range of new,well-motivated physics models and dark-sector scenarios have been proposed inthe last decade, predicting cosmogenic signals complementary to those in theconventional direct detection of particle-like dark matter. Most notably,various mechanisms to produce (semi-)relativistic DM particles in the presentuniverse (e.g. boosted dark matter) have been put forward, while beingconsistent with current observational and experimental constraints on DM. Theresulting signals often have less intense and more energetic fluxes, to whichunderground, kiloton-scale neutrino detectors can be readily sensitive. Inaddition, the scattering of slow-moving DM can give rise to a sizable energydeposit if the underlying dark-sector model allows for a large mass differencebetween the initial and final state particles, and the neutrino experimentswith large volume detectors are well suited for exploring these opportunities. This White Paper is devoted to discussing the scientific importance of thecosmogenic dark matter and exotic particle searches, not only overviewing therecent efforts in both the theory and the experiment communities but alsoproviding future perspectives and directions on this research branch. Alandscape of technologies used in neutrino detectors and their complementarityis discussed, and the current and developing analysis strategies are outlined.<br

Search for dinucleon decay into pions at Super-Kamiokande

A search for dinucleon decay into pions with the Super-Kamiokande detector has been performed with an exposure of 282.1 kiloton-years. Dinucleon decay is a process that violates baryon number by two units. We present the first search for dinucleon decay to pions in a large water Cherenkov detector. The modes $^{16}$O$(pp) \rightarrow$ $^{14}$C$\pi^{+}\pi^{+}$, $^{16}$O$(pn) \rightarrow$ $^{14}$N$\pi^{+}\pi^{0}$, and $^{16}$O$(nn) \rightarrow$ $^{14}$O$\pi^{0}\pi^{0}$ are investigated. No significant excess in the Super-Kamiokande data has been found, so a lower limit on the lifetime of the process per oxygen nucleus is determined. These limits are: $\tau_{pp\rightarrow\pi^{+}\pi^{+}} > 7.22 \times 10^{31}$ years, $\tau_{pn\rightarrow\pi^{+}\pi^{0}} > 1.70 \times 10^{32}$ years, and $\tau_{nn\rightarrow\pi^{0}\pi^{0}} > 4.04 \times 10^{32}$ years. The lower limits on each mode are about two orders of magnitude better than previous limits from searches for dinucleon decay in iron.Comment: 20 pages, 17 figures. Accepted for publication in Physical Review D on March 30, 201

Search for astronomical neutrinos from blazar TXS 0506+056 in super-kamiokande

We report a search for astronomical neutrinos in the energy region from several GeV to TeV in the direction of the blazar TXS 0506+056 using the Super-Kamiokande detector following the detection of a 100 TeV neutrinos from the same location by the IceCube collaboration. Using Super-Kamiokande neutrino data across several data samples observed from 1996 April to 2018 February we have searched for both a total excess above known backgrounds across the entire period as well as localized excesses on smaller timescales in that interval. No significant excess nor significant variation in the observed event rate are found in the blazar direction. Upper limits are placed on the electron- and muon-neutrino fluxes at the 90% confidence level as 6.0 × 10−7 and 4.5 × 10−7–9.3 × 10−10 [erg cm−2 s−1], respectively