Testing sterile neutrinos with new fixed target experiment at CERN SPS
- PDF / 537,143 Bytes
- 7 Pages / 612 x 792 pts (letter) Page_size
- 92 Downloads / 147 Views
esting Sterile Neutrinos with New Fixed Target Experiment at CERN SPS1, 2 D. S. Gorbunov Institute for Nuclear Research of RAS, Moscow, 117312 Russia email: [email protected] Abstract—We discuss the recently proposed new fixed target experiment at CERN with SPS beam of 400 GeV protons aimed at searches for sterile neutrinos produced in charmed hadron decays. The three ster ile neutrino introduced to the Standard Model can explain the active neutrino masses and mixings by means of seesaw type I mechanism, baryon asymmetry of the Universe by making use of leptogenesis via sterile active neutrino oscillations in the primordial plasma, and dark matter phenomenon due to a relic component of the lightest sterile neutrino. The new beamdump with detector placed as close to the target as possible will allow to test many other extensions of the Standard Model with new unstable yet longlived particles at GeV mass scale. DOI: 10.1134/S1063779615020112 1 2 1.
MAIN MOTIVATION: NEUTRINO PHYSICS
So far neutrino oscillations provide the only direct and convincing evidence for a hidden structure beyond the Standard Model of particle physics (SM). Phenomenological explanation of the observed oscil lations is achieved by introducing two neutrino mass 2 differences (so called solar, Δm sol , and atmospheric, 2
Δm atm , neutrino mass squared) and three angles to describe mixing between gauge (flavor) and mass eigenstates. The combined analysis of T2K and DayaBay data shows some hint of nonzero CPphase [1], more chances to probe it come with Novae experiment. The masses themselves are not fixed by the present experi ments. Naturally, one expects three nonzero masses. The hierarchy between the two observed mass differ 2 2 ences, Δm sol Δm atm , implies a hierarchical pattern in neutrino mass eigenstates, mi, i = 1, 2, 3: normal or inverted, see Fig. 1, left panel. Determining the type of neutrino mass hierarchy in oscillation experiment is a challenge. Combined analysis of cosmological data exhibits higher sensitivity to the neutrino masses, lim iting sum of neutrino mass i m i 0.5 eV, see Fig. 1, right panel. The final release of Planck experiment may exclude the inverted hierarchy scenario. Future galaxy surveys, e.g. provided by EUCLID, extend the
sensitivity of cosmological experiments to the normal hierarchy case [3]. Finally, If lepton number is violated in neutrino sector, there are two Majorana phases, to which oscillation experiments are blind. The Majo rana nature of neutrino masses may be tested by neu trinoless double βdecay experiments, sensitive to 2 |mee| = U m (see right panel of Fig. 1), where Uei i ei i stand for the elements of neutrino mixing matrix. Neutrino oscillations can be described with the SM field content by introducing nonrenormalizable dimension5 term
∑
ᏸ
at the International Workshop on Prospects of Particle Physics: “Neutrino Physics and Astrophysics”, Valday, Novgorod region, Russia January 26–February 2, 2014. 2 The article is published in the original.
F αβ ˜ † C = L α
Data Loading...
