The tightening of the constraints on the standard thermal WIMP scenario has forced physicists to propose alternative dark matter (DM) models. One of the most popular alternate explanations of the origin of DM is the non-thermal production of DM via freeze-in. In this scenario the DM never attains thermal equilibrium with the thermal soup because of its feeble coupling strength (∼ 10 −12 ) with the other particles in the thermal bath and is generally called the Feebly Interacting Massive Particle (FIMP). In this work, we present a gauged U(1) Lµ−Lτ extension of the Standard Model (SM) which has a scalar FIMP DM candidate and can consistently explain the DM relic density bound. In addition, the spontaneous breaking of the U(1) Lµ−Lτ gauge symmetry gives an extra massive neutral gauge boson Z µτ which can explain the muon (g − 2) data through its additional one-loop contribution to the process. Lastly, presence of three right-handed neutrinos enable the model to successfully explain the small neutrino masses via the Type-I seesaw mechanism. The presence of the spontaneously broken U(1) Lµ−Lτ gives a particular structure to the light neutrino mass matrix which can explain the peculiar mixing pattern of the light neutrinos.

With the advent of new and more sensitive direct detection experiments, scope for a thermal WIMP explanation of dark matter (DM) has become extremely constricted. The non-observation of thermal WIMP in these experiments has put a strong upper bound on WIMP-nucleon scattering cross section and within a few years it is likely to overlap with the coherent neutrino-nucleon cross section. Hence in all probability, DM may have some non-thermal origin. In this work we explore in detail this possibility of a non-thermal sterile neutrino DM within the framework of U(1)B−L model. The U(1)B−L model on the other hand is a well-motivated and minimal way of extending the standard model so that it can explain the neutrino masses via Type-I see-saw mechanism. We have shown, besides explaining the neutrino mass, it can also accommodate a non-thermal sterile neutrino DM with correct relic density. In contrast with the existing literature, we have found that W± decay can also be a dominant production mode of the sterile neutrino DM . To obtain the comoving number density of dark matter, we have solved here a coupled set of Boltzmann equations considering all possible decay as well as annihilation production modes of the sterile neutrino dark matter. The framework developed here though has been done for a U(1)B−L model, can be applied quite generally for any models with an extra neutral gauge boson and a fermionic non-thermal dark matter.

Recently there has been a hint of a gamma-ray line at 130 GeV originated from the galactic centre after the analysis of the Fermi-LAT satellite data. Being monochromatic in nature, it rules out the possibility of having its astrophysical origin and there has been a speculation that this line could be originated from dark matter annihilation. In this work, we propose a two component dark matter scenario where an extension of the Standard model by an inert Higgs doublet and a gauge singlet scalar concocted with Z 2 × Z ′ 2 symmetry, is considered. We find that our scenario can not only explain the 130 GeV gamma-ray line through dark matter annihilation but also produce the correct dark matter relic density. We have used the Standard Model Higgs mass around 125 GeV as intimated by the LHC data.

In solution-aged thin films, edge-on oriented ordering of nanofibers, along the z-direction, extends by thermal annealing, while near the film–substrate interface, it improves by combined solvent vapor and thermal annealing