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21.
Nikoleta Theodoropoulou Vinith Misra John Philip Patrick LeClair Geetha P. Berera Jagadeesh S. Moodera Biswarup Satpati Tapobrata Som 《Journal of magnetism and magnetic materials》2006,300(2):407-411
Clear evidence of ferromagnetic behavior at temperatures >400 K as well as spin polarization of the charge carriers have been observed in Zn1−xMnxO thin films grown on Al2O3 and MgO substrates. The magnetic properties depended on the exact Mn concentration and the growth parameters. In well-characterized single-phase films, the magnetic moment is 4.8 μB/Mn at 350 K, the highest moment yet reported for any Mn doped magnetic semiconductor. Anomalous Hall effect shows that the charge carriers (electrons) are spin-polarized and participate in the observed ferromagnetic behavior. 相似文献
22.
We consider the Littlest Higgs Model with T-parity (LHT), in the parameter region where a heavy neutrino is the lightest T-odd particle (LTP). Having emphasized that this corresponds to a sizable region in the parameter space of the theory, we show that both the Cryogenic Dark Matter Search (CDMS) and Xenon10 experiments disallow the entire region where the masses of the new particles in LHT can lie within several TeV. Therefore, any observation of the signals of a heavy neutrino LTP is likely to seriously reopen the issue of cold dark matter in the universe. 相似文献
23.
The forward asymmetry in the differential cross section for the photo disintegration of the deuteron has been calculated on the basis of a phenomenological theory for energies up to 80 MeV. The formulas for this asymmetry, which come from theE1-E2-andM1-M2-interference, are given, assuming the validity ofSiegert's theorem. TheE2-andM2-amplitudes are calculated approximately, using the Hulthén wavefunction with a 4% D-state admixture for the ground state and scattered waves determined by the phase shifts given by Marshak for the final states. The contribution of theM1-M2-interference turns out to be unimportant for the asymmetry, theE1-E2-interference giving the main effect. In the differential cross section,dσ/dΩ=a + b sin 2 ? + c cos ? + d cos ? sin 2 ?, we have obtained a very low value forc and the ratioc/d is approximately equal toa/3b. This is in contradiction to the assumptionc/d=a/b made in the previous analysis of the experimental data. This ratio seems to be insensitive to the value of the D-state admixture. For the lover energiesE γ=10 MeV andE γ=20 MeV the theoretical values for “d” are in agreement with the experimental ones. For the energies 54 and 80 MeV we have made a comparison of the theoretical differential cross sectiondσ/dΩ, taking into account the values for “a” and “b”, obtained in a former work ie, with the measureddσ/dΩ. 相似文献
24.
We point out that vector boson fusion at the Large Hadron Collider (LHC) can lead to useful signals for charginos and neutralinos in supersymmetric scenarios where these particles are almost invisible. The proposed signals are just two forward jets with missing transverse energy. It is shown that, in this way, one can put by far the strongest constraint on the parameter space of a theory with anomaly mediated supersymmetry breaking at the LHC. In addition, scenarios where the lightest neutralinos and charginos are Higgsino-like can give signals of the above type. 相似文献
25.
Debajyoti Choudhury Rahul Sinha S Arunagiri Gautam Bhattacharyya Debrupa Chakraverty Debajyoti Choudhury Amitava Datta Anindya Datta Aseskrishna Datta Amol Dighe Dilip Kumar Ghosh Anjan Giri Stephen King Anirban Kundu Rukmani Mohanta Biswarup Mukhopadhyaya Sreerup Raychaudhuri Saurabh Rindani Probir Roy DP Roy Sourov Roy AI Sanda Nita Sinha Rahul Sinha K Sridhar H Yamamoto 《Pramana》2000,55(1-2):335-345
This report summarises the work done during WHEPP-6 (Institute of Mathematical Sciences, Chennai, India, Jan 3–15, 2000) in
Working group on ‘B and collider physics’. 相似文献
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28.
Biswarup Das Debashish Goswami Kalyan B. Sinha 《Communications in Mathematical Physics》2014,330(2):435-467
We give a new method for proving the homomorphic property of a quantum stochastic flow satisfying a quantum stochastic differential equation with unbounded coefficients, under some further hypotheses. As an application, we prove a Trotter product formula for quantum stochastic flows and obtain quantum stochastic dilations of a class of quantum dynamical semigroups generalizing results of Goswami et al. (Inst H Poincare Probab Stat 41:505–522, 2005). 相似文献
29.
We propose a mechanism for the cage-opening reaction of a four atoms shared closo/closo B20H16 (1) with MeCN to a face shared closo/nido macropolyhedron B20H16(MeCN)2 (4) through a diamond-square-diamond rearrangement. Even though only one isomer of the product has been reported experimentally, our computational studies at the B3LYP/6-31G* level predict the possibility of the formation of the other isomers. Depending upon the position of the attack of the MeCN ligand on the polyhedral skeleton, different products are formed. The energetics of the reactions of B20H16 with Me2S and H2O are comparable. 相似文献
30.
Biswarup Pathak Devleena Samanta Prof. Dr. Rajeev Ahuja Prof. Dr. Purusottam Jena 《Chemphyschem》2011,12(13):2423-2428
Super‐ and hyperhalogens are a class of highly electronegative species whose electron affinities far exceed those of halogen atoms and are important to the chemical industry as oxidizing agents, biocatalysts, and building blocks of salts. Using the well‐known Wade–Mingos rule for describing the stability of closo‐boranes BnHn2? and state‐of‐the‐art theoretical methods, we show that a new class of super‐ and hyperhalogens, guided by this rule, can be formed by tailoring the size and composition of borane derivatives. Unlike conventional superhalogens, in which a central metal atom is surrounded by halogen atoms, the superhalogens formed according to the Wade–Mingos rule do not have to have either halogen or metal atoms. We demonstrate this by using B12H13 and its isoelectronic cluster CB11H12 as examples. We also show that while conventional superhalogens containing alkali atoms require at least two halogen atoms, a single borane‐like moiety is sufficient to give M(B12H12) clusters (M=Li, Na, K, Rb, Cs) superhalogen properties. In addition, hyperhalogens can be formed by using the above superhalogens as building blocks. Examples include M(B12H13)2 and M(CB11H12)2 (M=Li–Cs). This finding opens the door to an untapped source of superhalogens and weakly coordinating anions with potential applications. 相似文献