Chiral topological excitonic insulator in semiconductor quantum wells

We present a scheme to realize the chiral topological excitonic insulator in semiconductor heterostructures which can be experimentally fabricated with a coupled quantum well adjacent to twoferromagnetic insulating films. The different mean-field chiral topological orders, which are due to the change in the directions of the magnetization of the ferromagnetic films, can be characterized by the TKNN numbers in the bulk system as well as by the winding numbers of the gapless states in the edged system. Furthermore, we propose an experimental scheme to detect the emergence of the chiral gapless edge state and distinguish different chiral topological orders by measuring the thermal conductance.Comment: 14 pages, 4 figure

Note on Soft Graviton theorem by KLT Relation

Recently, new soft graviton theorem proposed by Cachazo and Strominger has inspired a lot of works. In this note, we use the KLT-formula to investigate the theorem. We have shown how the soft behavior of color ordered Yang-Mills amplitudes can be combined with KLT relation to give the soft behavior of gravity amplitudes. As a byproduct, we find two nontrivial identities of the KLT momentum kernel must hold.Comment: 25 page

Search for the signal of monotop production at the early LHC

We investigate the potential of the early LHC to discover the signal of monotops, which can be decay products of some resonances in models such as R-parity violating SUSY or SU(5), etc. We show how to constrain the parameter space of the models by the present data of $Z$ boson hadronic decay branching ratio, $K^0-\bar{K^0}$ mixing and dijet productions at the LHC. Then, we study the various cuts imposed on the events, reconstructed from the hadronic final states, to suppress backgrounds and increase the significance in detail. And we find that in the hadronic mode the information from the missing transverse energy and reconstructed resonance mass distributions can be used to specify the masses of the resonance and the missing particle. Finally, we study the sensitivities to the parameters at the LHC with $\sqrt{s}$=7 TeV and an integrated luminosity of $1 {\rm fb}^{-1}$ in detail. Our results show that the early LHC may detect this signal at 5$\sigma$ level for some regions of the parameter space allowed by the current data.Comment: 25 pages, 18 figures, 3 tables, version published in Phys.Rev.

PREPARATION OF BIODEGRADABLE FLAX SHIVE CELLULOSE-BASED SUPERABSORBENT POLYMER UNDER MICROWAVE IRRADIATION

Superabsorbent polymer was prepared by graft polymerization of acrylic acid onto the chain of cellulose from flax shive by using potassium persulfate (KPS) as an initiator and N,N’-methylenebisacrylamide (MBA) as a crosslinker under microwave irradiation. SEM photographs were also studied for more information about the shive, cellulose from shive, and the superabsorbent polymer. The structure of the graft copolymer was confirmed by FT-IR spectroscopy and thermogravimetric analysis (TGA). The biodegradability in soil was measured at 32 and 40 oC. The polymer was porous, and thermal stability of the polymer was observed up to approximately 200 oC. FT-IR analysis indicated that acrylic acid in polymer was successfully grafted onto the cellulose. The graft copolymer was found to be an effective superabsorbent resin, rapidly absorbing water to almost 1000 times its own dry weight at pH around 7.3. The water absorbency in 0.9% NaCl, KCl, FeCl3 solutions and urine were 56.47 g/g, 54.71g/g, 9.89g/g and 797.21g/g, respectively. The product biologically degraded up to 40% at 40 oC in 54 days, which shows good biodegradability