A facility to search for hidden particles at the CERN SPS: the SHiP physics case

This paper describes the physics case for a new fixed target facility at CERN SPS. The SHiP (search for hidden particles) experiment is intended to hunt for new physics in the largely unexplored domain of very weakly interacting particles with masses below the Fermi scale, inaccessible to the LHC experiments, and to study tau neutrino physics. The same proton beam setup can be used later to look for decays of tau-leptons with lepton flavour number non-conservation, [Formula: see text] and to search for weakly-interacting sub-GeV dark matter candidates. We discuss the evidence for physics beyond the standard model and describe interactions between new particles and four different portals-scalars, vectors, fermions or axion-like particles. We discuss motivations for different models, manifesting themselves via these interactions, and how they can be probed with the SHiP experiment and present several case studies. The prospects to search for relatively light SUSY and composite particles at SHiP are also discussed. We demonstrate that the SHiP experiment has a unique potential to discover new physics and can directly probe a number of solutions of beyond the standard model puzzles, such as neutrino masses, baryon asymmetry of the Universe, dark matter, and inflation.

What is the Flavor of the Cosmic Neutrinos Seen by IceCube?

We analyze the high-energy neutrino events observed by IceCube, aiming to probe the initial flavor of cosmic neutrinos. We study the track-to-shower ratio of the subset with energy above 60 TeV, where the signal is expected to dominate, and show that different production mechanisms give rise to different predictions even accounting for the uncertainties due to neutrino oscillations. We include for the first time the passing muons observed by IceCube in the analysis. They corroborate the hypotheses that cosmic neutrinos have been seen and their flavor matches expectations derived from the neutrino oscillations.

Using low-energy neutrinos from pion decay at rest to probe the proton strangeness

The study of the neutral current elastic scattering of neutrinos on protons at lower energies can be used as a compelling probe to improve our knowledge of the strangeness of the proton. We consider a neutrino beam generated from pion decay at rest, as provided by a cyclotron or a spallation neutron source and a 1 kton scintillating detector with a potential similar to the Borexino detector. Despite several backgrounds from solar and radioactive sources, it is possible to estimate two optimal energy windows for the analysis, one between 0.65 and 1.1 MeV and another between 1.73 and 2.2 MeV. The expected number of neutral current events in these two regions, for an exposure of 1 yr, is enough to obtain an error on the strange axial charge 10 times smaller than available at present.

Left-right symmetry: from the LHC to neutrinoless double beta decay

The Large Hadron Collider has the potential to probe the scale of left-right symmetry restoration and the associated lepton number violation. Moreover, it offers the hope of measuring the right-handed leptonic mixing matrix. We show how this, together with constraints from lepton flavor violating processes, can be used to make predictions for neutrinoless double beta decay. We illustrate this connection in the case of the type-II seesaw.

Neutrinos from supernovae as a trigger for gravitational wave search

Exploiting an improved analysis of the nue signal from the explosion of a galactic core collapse supernova, we show that it is possible to identify within about 10 ms the time of the bounce, which is strongly correlated to the time of the maximum amplitude of the gravitational signal. This allows us to precisely identify the gravitational wave burst timing.

B-tau unification and large atmospheric mixing: a case for a noncanonical seesaw mechanism

We study the second and third generation masses in the context of the minimal renormalizable SO(10) theory. We show that if the seesaw takes the noncanonical (type II) form, large atmospheric neutrino mixing angle requires b-tau unification.