Occurrence of Hysteresis like behavior of resistance of Sb2Te3Sb_2 Te_3 film in heating-cooling cycle

Experimental observations of a peculiar behavior observed on heating and cooling ${\rm Sb_2Te_3}$ films at different heating and cooling rate are detailed. The film regained its original resistance, forming a closed loop, on the completion of the heating-cooling cycle which was reproducible for identical conditions of heating and cooling. The area enclosed by the loop was found to depend on (i) the thickness of the film, (ii) the heating rate, (iii) the maximum temperature to which film was heated and (iv) the cooling rate. The observations are explained on basis of model which considers the film to be a resultant of parallel resistances. The film's finite thermal conductivity gives rise to a temperature gradient along the thickness of the film, due to this and the temperature coefficient of resistance, the parallel combination of resistance changes with temperature. Difference in heating and cooling rates give different temperature gradient, which explains the observed hysteresis.Comment: 21 pages and 10 figure

Jet substructure shedding light on heavy Majorana neutrinos at the LHC

The existence of tiny neutrino masses and flavor mixings can be explained naturally in various seesaw models, many of which typically having additional Majorana type SM gauge singlet right handed neutrinos ($N$). If they are at around the electroweak scale and furnished with sizeable mixings with light active neutrinos, they can be produced at high energy colliders, such as the Large Hadron Collider (LHC). A characteristic signature would be same sign lepton pairs, violating lepton number, together with light jets -- $pp\to N\ell^{\pm}, \; N\to\ell^{\pm}W^{\mp}, \; W^{\mp}\to jj$. We propose a new search strategy utilising jet substructure techniques, observing that for a heavy right handed neutrino mass $M_N$ much above $M_{W^\pm}$, the two jets coming out of the boosted $W^\pm$ may be interpreted as a single fat-jet ($J$). Hence, the distinguishing signal topology will be $\ell^{\pm}\ell^{\pm} J$. Performing a comprehensive study of the different signal regions along with complete background analysis, in tandem with detector level simulations, we compute statistical significance limits. We find that heavy neutrinos can be explored effectively for mass ranges $300$ GeV $\leq M_N \leq 800$ GeV and different light-heavy neutrino mixing $|V_{\mu N}|^{2}$. At the 13 TeV LHC with 3000 $\mathrm{fb}^{-1}$ integrated luminosity one can competently explore mixing angles much below present LHC limits, and moreover exceed bounds from electroweak precision data.Comment: Accepted for publication in JHEP. 25 pages, 8 figures, 1 tabl

Graviton modes in multiply warped geometry

The negative results in the search for Kaluza-Klein graviton modes at the LHC, when confronted with the discovery of the Higgs, has been construed to have severely limited the efficacy of the Randall-Sundrum model as an explanation of the hierarchy problem. We show, though, that the presence of multiple warping offers a natural resolution of this conundrum through modifications in both the graviton spectrum and their couplings to the Standard Model fields.Comment: 16 pages, 6 figure