Search This Blog

Monday, November 21, 2011

Majorana particles

The recent data released by OPERA experiment confirm the superluminal propagation of muonic neutrinos in the Earth’s crust with overall significance of  6.2σ
Particles contacting certain phase boundaries generate Majorana particles which transport the energy through the medium. The boundary between a room temperature superconductor and a topological insulator might be such an instance. The Majorana equation has solutions with imaginary values for the mass indicating superluminal propagation. The energy of the particles is not only proportional to the intrinsic mass time the square of the speed of light, but inversely proportional to the intrinsic spin plus 1/2.
It is known that massive particles that are their own antiparticles, i.e., Majorana particles, can possess only one specific type of multipolar moments---the so-called toroidal moments (anapole moment and multipoles of that). Unlike the familiar charge and magnetic moments, these moments do not directly interact with the (external) static electromagnetic fields but only with the external current, and hence lead to contact interactions. On the other hand, massless Majorana particles, with the exception of those with spin 1/2, do not have any electromagnetic form factor. It is also found that regardless of the spin of the Majorana particle the differential cross section for the production of a Majorana pair by a spin-1 particle at a high-energy electron-positron machine has a unique angular distribution.

Experimental results:

(1) The OPERA result on the order of magnitude of the effective muon-neutrino velocity:
[v μ(10 GeV) c ]/c  ∼  0.00001.

(2) The supernova SN1987a bound on the effective electron-antineutrino velocity:
v e(10 MeV) c |/c <  ∼ 0.000000001.

(3) The absence of catastrophic energy losses from the vacuum-Cherenkov-type process
μ μ+Z0 μ+e+e+ for the CERN–GranSasso (CNGS) neutrinos, in particular.

(4) The existence of mass-difference neutrino oscillations, which requires nearly equal maximum velocity of the three known flavors
f = (e, μ, tau ) of neutrinos.

(5) The negligible leakage of Lorentz violation in the neutrino sector to the charged-lepton
sector by quantum effects, e.g., loop corrections to the electron propagator.

No comments:

Post a Comment