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1.
Erythrinin A () has been synthesised by the oxidative rearrangement of dihydropyranochalcone with thallium(III) nitrate (TTN) in trimethyl orthoformate (TMOF) to the dimethyl acetal , followed by cyclisation to , demethylation to and dehydrogenation. Compound could also be obtained from chalcone on similar rearrangement followed by cyclisation, demethoxymethylation and dehydrogenation. In another route, chalcone was oxidatively rearranged with TTN in TMOF, to which on treatment with HCl yielded . 相似文献
2.
It is well known that the study of flavour physics and CP violation is very important to critically test the Standard Model
and to look for possible signature of new physics beyond it. The observation of CP violation in kaon system in 1964 has ignited
a lot of experimental and theoretical efforts to understand its origin and to look for CP violation effects in other systems
besides the neutral kaons. The two B-factories BABAR and BELLE, along with other experiments, in the last decade or so made studies in flavour physics and CP
violation a very interesting one. In this article we discuss the status and prospectives of the flavour physics associated
with the strange, charm and bottom sectors of the Standard Model. The important results in kaon sector will be briefly discussed.
Recently, mixing in the charm system has been observed, which was being pursued for quite some time without any success. The
smallness of the mixing parameters in the charm system is due to the hierarchical structure of the CKM matrix. Interestingly,
so far we have not found CP violation in the charm system but in the future, with more dedicated experiments at charm threshold,
the situation could change. Many interesting observations have been made in the case of bottom mesons and some of them show
some kind of deviations from that of the Standard Model expectations which are mainly associated with the b → s flavour changing neutral current transitions. It is long believed that the B
s
system could be the harbinger of new physics since it is a system in which both bottom and strange quarks are the constituents.
Recently, D0 and CDF announced their result for the B
s
mixing which is claimed to be the first possible new physics signature in the flavour sector. We plan to touch upon all important
issues pointing out both theoretical and experimental developments and future prospects in this review article. 相似文献
3.
Suchismita Sahoo Rukmani Mohanta 《The European Physical Journal C - Particles and Fields》2017,77(5):344
We study the effect of the scalar leptoquark and \(Z^\prime \) boson on the rare decays of the D mesons involving flavour changing transitions \(c \rightarrow u l^+ l^- (l^{\mp }_i l^{\,\pm \,}_j)\). We constrain the new physics parameter space using the branching ratio of the rare decay mode \(D^0 \rightarrow \mu ^+ \mu ^-\) and the \(D^0 - {\bar{D}}^0\) oscillation data. We compute the branching ratios, forward–backward asymmetry parameters and flat terms in \(D^{+(0)} \rightarrow \pi ^{+(0)} \mu ^+ \mu ^-\) processes using the constrained parameters. The branching ratios of the lepton flavour violating D meson decays, such as \(D^0 \rightarrow \mu e, ~\tau e\) and \(D^{+(0)} \rightarrow \pi ^{+(0)} \mu ^- e^+\) are also investigated. 相似文献
4.
This paper deals with a multiserver feedback retrial queueing system with finite waiting position and constant retrial rate. This system is analyzed as a quasi-birth-and-death (QBD) process and the necessary and sufficient condition for stability of the system is investigated. Some important system performance measures are obtained using matrix geometric method. The effect of various parameters on the system performance measures are illustrated numerically. Finally, the algorithmic development of the full busy period for the model under consideration is discussed. 相似文献
5.
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
6.
Effect of FCNC mediated <Emphasis Type="Italic">Z</Emphasis> boson on lepton flavor violating decays
We study the three body lepton flavor violating (LFV) decays μ ?→e ? e + e ?, \(\tau^{-} \to l_{i}^{-} l_{j}^{+} l_{j}^{-}\) and the semileptonic decay τ→μφ in the flavor changing neutral current (FCNC) mediated Z boson model. We also calculate the branching ratios for LFV leptonic B decays, B d,s →μe, B d,s →τe, B d,s →τμ and the conversion of muon to electron in Ti nucleus. The new physics parameter space is constrained by using the experimental limits on μ ?→e ? e + e ? and τ ?→μ ? μ + μ ?. We find that the branching ratios for τ→eee and τ→μφ processes could be as large as \({\sim}{\mathcal{O}}(10^{-8})\) and \(\mathrm{Br}(B_{d,s} \to \tau \mu,~ \tau e) \sim {\mathcal{O}}(10^{-10})\). For other LFV B decays the branching ratios are found to be too small to be observed in the near future. 相似文献
7.
8.
Rukmani Mohanta 《Physics letters. [Part B]》2002,540(3-4):241-246
The rare decay B+→Ds+φ can occur only via annihilation type diagram in the standard model. The small branching ratio predicted in the standard model makes this channel sensitive to new physics contributions. We analyze this decay mode, both in the standard model and in several extensions of it. The models considered are minimal supersymmetric model with R-parity violation and two Higgs doublet model. The experimental verification of our findings of large branching ratio and/or nonzero CP asymmetry may signal the presence of new physics. 相似文献
9.
Mohammad Mahbubur Rahman K. Rukmani Rajam Sekhar S. Asokan 《Journal of Non》2012,358(12-13):1501-1505
Photo-thermal Deflection (PTD) technique is used to investigate the thermal diffusivity (α) of Ge17Te83 ? xTlx (0 ≤ x ≤ 13) glasses as a function of composition. The thermal diffusivity of these glasses is found to lie in the range 0.020 to 0.048 cm2/s, which is consistent with the memory type of electrical switching exhibited by these samples. Further, it is found that α shows an initial increase with Tl addition, followed by a decrease. The observed composition dependence of thermal diffusivity has been understood on the basis that the thallium atoms are incorporated as a covalent species for lower values of x, increasing the network rigidity; however, they enter as ionic species for higher x values, fragmenting the network. The initial increase in α is due to the increasing network rigidity and the subsequent decrease is because of the fragmentation of the network. Also, there is a strong correlation between the composition dependence of switching voltages observed earlier and the variation with composition of electrical resistivity and thermal diffusivity of Ge17Te83 ? xTlx glasses obtained in the present study. 相似文献
10.
Synthesis and characterization of liquid–crystalline polyesters with chiral and achiral twin spacers
Rukmani Srinivasan Ganga Radhakrishnan 《Journal of polymer science. Part A, Polymer chemistry》2001,39(10):1743-1752
A series of novel thermotropic main-chain chiral liquid–crystalline random copolyesters consisting of spacers of two different types—chiral and achiral—was synthesized. Polyesters (BmTa) with tartaric acid as the chiral spacer (Ta), aliphatic diols (with ‘m’ = 2–10 methylene groups) as the achiral spacers, and 4,4′-dihydroxy biphenyl (B) as the mesogen were synthesized via condensation polymerization in solution after duly protecting the 2,3-dihydroxy groups of tartaric acid by acetylation. The copolymers were characterized by Fourier transform infrared spectroscopy, 1H and 13C NMR spectra, gel permeation chromatography, and thermogravimetric analysis. Transition temperatures for phase changes recorded by DSC were corroborated with the textures observed by a hot-stage optical polarizing microscope. The wide-angle X-ray diffraction (WAXD) profiles indicated a SmE phase at room temperature. The lower angle region at 2θ = 0.5–2.45 covered by WAXD indicated a layer of thickness of 161 Å, less than the molecular length for B0Ta. The [αD] values were recorded on a digital polarimeter. The birefringence was lost at higher mesophase temperatures in lower members with m < 5, a behavior found in certain chiral systems, and the higher members with m > 5 showed a lesser number of phase transitions. On cooling, the polyesters produced a texture with the formation of transition bars. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1743–1752, 2001 相似文献