Modern Physics Letters A

Recently data from PAMELA, ATIC, FERMI-LAT and HESS show that there are e^± excesses in the cosmic ray energy spectrum. PAMELA shown excesses only in e⁺, but not in anti-proton spectrum. ATIC, FERMI-LAT and HESS shown excesses in e⁺+e^- spectrum, but the detailed shapes are different which requires future experimental observations to pin down the correct data set. Nevertheless a lot of efforts have been made to explain the observed e^± excesses, and also why PAMELA only has excesses in e⁺ but not in anti-proton. In this brief review we discuss one of the most popular mechanisms to explain the data — the dark matter annihilation. It has long been known that about 23% of our universe is made of relic dark matter. If the relic dark matter was thermally produced, the annihilation rate is constrained resulting in the need of a large boost factor to explain the data. We will discuss in detail how a large boost factor can be obtained by the Sommerfeld and Breit–Wigner enhancement mechanisms. Some implications for particle physics model buildings will also be discussed.

If neutrino masses are obtained via the canonical seesaw mechanism, based on an underlying 2 ×2 mass matrix, unitarity violation of the neutrino mixing matrix is unavoidable, but its effect is extremely small. On the other hand, in the inverse (and linear) seesaw mechanisms, based on an underlying 3 ×3 mass matrix, it can be significant and possibly observable. This 3 ×3 matrix is examined in more detail, and a new variation (the lopsided seesaw) is proposed which has features of both mechanisms. A concrete example based on U(1)_N is discussed.

The constituent quarks are interpreted as bound states, which have an internal structure. The quark distributions of the proton are related to those of the constituent quarks. The experiments support this hypothesis. Likewise the spin structure of the proton is related to the spin structure of the constituent quarks. We find that about 30% of the spin of a constituent quark is given by the valence quark, and 70% are provided by the gluons.

The weak currents with respect to the diagonal neutral bosons Z, Z′ and Z^′′ of a specific SU(4)_L⊗U(1)_Y gauge model are computed in detail for all the fermion families involved therein. Our algebraical approach, which is based on the general method of solving gauge models with high symmetries proposed several years ago by Cotăescu, recovers in a nontrivial way all the Standard Model values for current couplings of the traditional leptons and quarks, and predicts plausible values for those of the exotic fermions in the model.

Using the effective Lagrangian method, we analyze the corrections to the branching ratio b→sγ from the Higgs sector in the standard model. The numerical result indicates that the corrections from this sector to b→sγ is about -2% as m_h~ 0.5 TeV.

In this paper, the Hawking radiation from the slowly varying nonstationary Reissner–Nordström black hole is discussed through the fermions tunnelling theory, assuming a reasonable form of gamma matrix, and even researching on the issues with following coordinate transformation, which is a new method to study fermions' Hawking tunnelling radiation from slowly varying nonstationary Reissner–Nordström black hole.

A model where chiral boson is coupled to a background dilaton field is considered to study the s-wave scattering of fermion by a background dilaton black hole. It is found that the scattering process of chiral fermion does not violate unitarity and information remains preserved. Faddevian anomaly plays a crucial role on the information scenario.

We show that the intriguing localization of a free particle wave-packet is possible due to a hidden scale present in the system. Self-adjoint extensions (SAE) is responsible for introducing this scale in quantum mechanical models through the nontrivial boundary conditions. We discuss a couple of classically scale invariant free particle systems to illustrate the issue. In this context it has been shown that a free quantum particle moving on a full line may have localized wave-packet around the origin. As a generalization, it has also been shown that particles moving on a portion of a plane or on a portion of a three-dimensional space can have unusual localized wave-packet.