Symmetries and unitary interactions of mass dimension one fermionic dark matter

The fermionic fields constructed from Elko have several unexpected properties. They satisfy the Klein-Gordon but not the Dirac equation and are of mass dimension one instead of three-half. Starting with the Klein-Gordon Lagrangian, we initiate a careful study of the symmetries and interactions of these fermions and their higher-spin generalisations. We find, although the fermions are of mass dimension one, the four-point fermionic self-interaction violates unitarity at high-energy. Therefore, it cannot be a fundamental interaction of the theory. It follows that for the spin-half fermions, the demand of renormalisability and unitarity forbids four-point interactions and only allows for the Yukawa interaction. For fermions with spin j>1/2, they have no renormalisable or unitary interactions. Since the theory is described by a Klein-Gordon Lagrangian, the interaction generated by the local $U(1)$ gauge symmetry which contains a four-point interaction, is excluded by the demand of renormalisability. In the context of the Standard Model, these properties make the spin-half fermions natural dark matter candidates.Comment: 20 pages, 5 figure

Mass dimension one fermions from flag dipole spinors

According to the Lounesto classification, there are six classes of spinors. The Dirac and Weyl spinors belong to the first three and the sixth classes respectively. The remaining fourth and fifth classes are known as the flag dipole and flag pole spinors respectively. In this letter, a mass dimension one fermionic field with flag dipole spinors as expansion coefficients is constructed. These spinors are shown to be related to Elko (flag pole spinors) by a matrix transformation. It shows that the flag dipole spinors are generalizations of Elko. To construct a Lorentz-covariant quantum field, an infinitesimal deformation is applied to the spinor dual. Subsequently, we show that the fermionic fields constructed from Elko and flag dipole spinors are physically equivalent.Comment: 10 page

Penguin-induced Radiative Baryonic B Decays Revisited

Weak radiative baryonic B decays $\bar B\to B_1\bar B_2\gamma$ mediated by the electromagnetic penguin process $b\to s\gamma$ are re-examined within the framework of the pole model. The meson pole contribution that has been neglected before is taken into account in this work. It is found that the intermediate $K^*$ contribution dominates in the $\Sigma\bar p\gamma$ mode and is comparable to the baryon pole effect in $\Lambda\bar p\gamma$ and $\Xi\bar\Lambda\gamma$ modes. The branching ratios for $B^-\to\Lambda\bar p\gamma$ and $B^-\to\Xi^0\bar\Sigma^-\gamma$ are of order $2.6\times 10^{-6}$ and $6\times 10^{-7}$, respectively. The threshold enhancement effect in the dibaryon mass spectrum is responsible by the meson pole diagram. We also study the angular distribution of the baryon in the dibaryon rest frame. The baryon pole diagrams imply that the antibaryon tends to emerge in the direction of the photon in the baryon-pair rest frame. The predicted angular asymmetry agrees with experiment for $B^-\to\Lambda\bar p\gamma$. Measurements of the correlation of the photon with the baryon allow us to discriminate between different models for describing the radiative baryonic B decays. For decays $B\to\Xi\bar\Sigma\gamma$, a large correlation of the photon to the $\bar\Sigma$ and a broad bump in the dibaryon mass spectrum are predicted.Comment: 10 pages, 4 figure

Magnetic field creation by solar mass neutrino jets

Parity violation and its effects for neutrinos in astrophysical contexts have been considered earlier in pioneering papers of Hawking and Vilenkin. But because even the largest magnetic moments predicted by physics beyond the Standard Model are some twelve orders of magnitude smaller than the Bohr magneton, their implications for magnetic field generation and neutrino oscillations are generally considered insignificant. Here we show that since in astrophysical scenarios a huge number of neutrinos may be emitted, the smallness of the magnetic moment, when coupled with parity violation, is compensated by the sheer number of neutrinos. The merger of neutron stars would leave behind a short pulse of electromagnetic synchrotron radiation even if the neutrino jet in the merger points away from the neutrino detectors. We show that the magnetic field can be as large as 10^6\,\mbox{Gauss} and comment on the possibility of direct detection. Observation of such a pulse would lend strong support for neutrino magnetic moments and resolve the missing neutrino problem in neutron star mergers.Comment: 5 pages, version accepted for publication in Europhysics Letters (EPL

A QFT-induced phase in neutrino flavour oscillations

In the extended Standard Model of particle physics, each neutrino mass eigenstate is predicted to have a tiny but non vanishing magnetic moment induced by quantum field theoretic corrections. These QFT-induced magnetic momenta depend linearly on masses of the underlying mass eigenstates with a proportionality constant ${3eG_{F}}/{(8\sqrt{2}\pi^{2})}$. As a consequence when neutrinos are embedded in an environment containing magnetic fields the flavour oscillations get a contribution from the induced relative phases.Comment: 6 page