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In this paper, we present the physics performance of the ESSnuSB experiment in the standard three flavor scenario using the updated neutrino flux calculated specifically for the ESSnuSB configuration and updated migration matrices for the far detector. Taking conservative systematic uncertainties corresponding to a normalization error of $5%$ for signal and $10%$ for background, we find that there is $10sigma$ $(13sigma)$ CP violation discovery sensitivity for the baseline option of 540 km (360 km) at $delta_{rm CP} = pm 90^circ$. The corresponding fraction of $delta_{rm CP}$ for which CP violation can be discovered at more than $5 sigma$ is $70%$. Regarding CP precision measurements, the $1sigma$ error associated with $delta_{rm CP} = 0^circ$ is around $5^circ$ and with $delta_{rm CP} = -90^circ$ is around $14^circ$ $(7^circ)$ for the baseline option of 540 km (360 km). For hierarchy sensitivity, one can have $3sigma$ sensitivity for 540 km baseline except $delta_{rm CP} = pm 90^circ$ and $5sigma$ sensitivity for 360 km baseline for all values of $delta_{rm CP}$. The octant of $theta_{23}$ can be determined at $3 sigma$ for the values of: $theta_{23} > 51^circ$ ($theta_{23} < 42^circ$ and $theta_{23} > 49^circ$) for baseline of 540 km (360 km). Regarding measurement precision of the atmospheric mixing parameters, the allowed values at $3 sigma$ are: $40^circ < theta_{23} < 52^circ$ ($42^circ < theta_{23} < 51.5^circ$) and $2.485 times 10^{-3}$ eV$^2 < Delta m^2_{31} < 2.545 times 10^{-3}$ eV$^2$ ($2.49 times 10^{-3}$ eV$^2 < Delta m^2_{31} < 2.54 times 10^{-3}$ eV$^2$) for the baseline of 540 km (360 km).
We discuss an experiment to investigate neutrino physics at the LHC in Run 3, with emphasis on tau flavour. As described in our previous paper [arXiv:1903.06564v1], the detector can be installed in the decommissioned TI18 tunnel, about 480 m downstream the ATLAS cavern, after the first bending dipoles of the LHC arc. In that location, the prolongation of the beam Line-of-Sight from Interaction Point IP1 to TI18 traverses about 100 m of rock. The detector intercepts the intense neutrino flux, generated by the LHC beams colliding in IP1, at large pseudorapidity eta, where neutrino energies can exceed a TeV. This paper focuses on optimizing global features of the experiment, like detector mass and acceptance. Since the neutrino-nucleon interaction cross section grows almost linearly with energy, the detector can be light and still collect a considerable sample of neutrino events; in the present study it weighs less than 3 tons. The detector is positioned off the beam axis, slightly above the ideal prolongation of the LHC beam from the straight section, covering 7.4 < eta < 9.2. In this configuration, the flux at high energies (0.5-1.5 TeV and beyond) is found to be dominated by neutrinos originating directly from IP1, mostly from charm decays, of which about 50% are electron neutrinos and about 5% are tau neutrinos. The contribution of pion and kaon decays to the muon neutrino flux is studied by means of simulations that embed the LHC optics and found small at high energies. The above studies indicate that with 150 /fb of delivered LHC luminosity in Run 3 the experiment can record a few thousand very high energy neutrino charged current interactions and over 50 tau neutrino charged current events.
The main physical results on the registration of solar neutrinos and the search for rare processes obtained by the Borexino collaboration to date are presented.
We studied the radiative muon decay $mu^+ to e^+ ubar{ u}gamma$ by using for the first time an almost fully polarized muon source. We identified a large sample (~13000) of these decays in a total sample of 1.8x10^14 positive muon decays collected in the MEG experiment in the years 2009--2010 and measured the branching ratio B($mu^+ to e^+ ubar{ u}gamma$) = (6.03+-0.14(stat.)+-0.53(sys.))x10^-8 for E_e > 45 MeV and E_{gamma} > 40 MeV, consistent with the Standard Model prediction. The precise measurement of this decay mode provides a basic tool for the timing calibration, a normalization channel, and a strong quality check of the complete MEG experiment in the search for $mu^+ to e^+gamma$ process.
FASER, the ForwArd Search ExpeRiment, is a proposed experiment dedicated to searching for light, extremely weakly-interacting particles at the LHC. Such particles may be produced in the LHCs high-energy collisions in large numbers in the far-forward region and then travel long distances through concrete and rock without interacting. They may then decay to visible particles in FASER, which is placed 480 m downstream of the ATLAS interaction point. In this work, we describe the FASER program. In its first stage, FASER is an extremely compact and inexpensive detector, sensitive to decays in a cylindrical region of radius R = 10 cm and length L = 1.5 m. FASER is planned to be constructed and installed in Long Shutdown 2 and will collect data during Run 3 of the 14 TeV LHC from 2021-23. If FASER is successful, FASER 2, a much larger successor with roughly R ~ 1 m and L ~ 5 m, could be constructed in Long Shutdown 3 and collect data during the HL-LHC era from 2026-35. FASER and FASER 2 have the potential to discover dark photons, dark Higgs bosons, heavy neutral leptons, axion-like particles, and many other long-lived particles, as well as provide new information about neutrinos, with potentially far-ranging implications for particle physics and cosmology. We describe the current status, anticipated challenges, and discovery prospects of the FASER program.
The MoEDAL experiment at the LHC is optimised to detect highly ionising particles such as magnetic monopoles, dyons and (multiply) electrically charged stable massive particles predicted in a number of theoretical scenarios. MoEDAL, deployed in the LHCb cavern, combines passive nuclear track detectors with magnetic monopole trapping volumes (MMTs), while spallation-product backgrounds are being monitored with an array of MediPix pixel detectors. An introduction to the detector concept and its physics reach, complementary to that of the large general purpose LHC experiments ATLAS and CMS, will be given. Emphasis is given to the recent MoEDAL results at 13 TeV, where the null results from a search for magnetic monopoles in MMTs exposed in 2015 LHC collisions set the world-best limits on particles with magnetic charges more than 1.5 Dirac charge. The potential to search for heavy, long-lived supersymmetric electrically-charged particles is also discussed.