Exchange bias effect and intragranular magnetoresistance in Nd$_{0.84}Sr_{0.16}CoO_3

Electrical transport properties as a function of magnetic field and time have been investigated in polycrystalline, Nd_{0.84}Sr_{0.16}CoO_3. A strong exchange bias (EB) effect is observed associated with the fairly large intragranular magnetoresistance (MR). The EB effect observed in the MR curve is compared with the EB effect manifested in magnetic hysteresis loop. Training effect, described as the decrease of EB effect when the sample is successively field-cycled at a particular temperature, has been observed in the shift of the MR curve. Training effect could be analysed by the successful models. The EB effect, MR and a considerable time dependence in MR are attributed to the intrinsic nanostructure giving rise to the varieties of magnetic interfaces in the grain interior

No-go theorems for \psi-epistemic models based on a continuity assumption

The quantum state \psi is a mathematical object used to determine the probabilities of different outcomes when measuring a physical system. Its fundamental nature has been the subject of discussions since the inception of quantum theory: is it ontic, that is, does it correspond to a real property of the physical system? Or is it epistemic, that is, does it merely represent our knowledge about the system? Assuming a natural continuity assumption and a weak separability assumption, we show here that epistemic interpretations of the quantum state are in contradiction with quantum theory. Our argument is different from the recent proof of Pusey, Barrett, and Rudolph and it already yields a non-trivial constraint on \psi-epistemic models using a single copy of the system in question.Comment: Version 1 contains both theory and an illustrative experiment. Version 2 contains only the theory (the experiment with expanded discussion will be posted separatly at a later date). The main novelty of Version 2 is a detailed comparison in appendix 2 with L. Hardy arXiv:1205.14396. Version 2 is 6 pages of text and 1 figure; v3: minor change

Stringent Dilepton Bounds on Left-Right Models using LHC data

In canonical left-right symmetric models the lower mass bounds on the charged gauge bosons are in the ballpark of $3-4$ TeV, resulting into much stronger limits on the neutral gauge boson $Z_R$, making its production unreachable at the LHC. However, if one evokes different patterns of left-right symmetry breaking the $Z_R$ might be lighter than the $W_R^\pm$ motivating an independent $Z_R$ collider study. In this work, we use the 8 TeV ATLAS $20.3$ fb$^{-1}$ luminosity data to derive robust bounds on the $Z_R$ mass using dilepton data. %because they provide the most restrictive limits due to the sizable $Z_R$-lepton couplings. We find strong lower bounds on the $Z_R$ mass for different right-handed gauge couplings, excluding $Z_R$ masses up to $\sim 3.2$TeV. For the canonical LR model we place a lower mass bound of $\sim 2.5$TeV. Our findings are almost independent of the right-handed neutrino masses ($\sim 2\,\%$ effect) and applicable to general left-right models.Comment: 5 pages, 3 figures, 1 table. To appear in Phys. Lett.