Open String Descriptions of Space-like Singularities in Two Dimensional String Theory

The matrix model formulation of two dimensional string theory has been shown to admit time dependent classical solutions whose closed string duals are geodesically incomplete space-times with space-like boundaries. We investigate some aspects of the dynamics of fermions in one such background. We show that even though the background solution appears pathological, the time evolution of the system is smooth in terms of open string degrees of freedom, viz. the fermions. In particular, an initial state of fermions evolves smoothly into a well defined final state over an infinite open string time interval, while the time perceived by closed strings appears to end abruptly. We outline a method of calculating fermion correlators exactly using symmetry properties. The result for the two point function is consistent with the semiclassical picture.Comment: LaTeX 8 eps figures, referenced adde

Muon anomaly and a lower bound on higgs mass due to a light stabilized radion in the Randall-Sundrum model

We investigate the Randall-Sundrum model with a light stabilized radion (required to fix the size of the extra dimension) in the light of muon anomalous magnetic moment $a_\mu [= \frac{(g - 2)}{2}]$. Using the recent data (obtained from the E821 experiment of the BNL collaboration) which differs by $2.6 \sigma$ from the Standard Model result, we obtain constraints on radion mass \mphi and radion vev \vphi. In the presence of a radion the beta functions \beta(\l) and $\beta(g_t)$ of higgs quartic coupling (\l) and top-Yukawa coupling ($g_t$) gets modified. We find these modified beta functions. Using these beta functions together with the anomaly constrained \mphi and \vphi, we obtain lower bound on higgs mass $m_h$. We compare our result with the present LEP2 bound on $m_h$.Comment: Version to be appeared in IJMP

Topological Structure of the Vacuum, Cosmological Constant and Dark Energy

In this review we present a theory of cosmological constant and Dark Energy (DE), based on the topological structure of the vacuum. The Multiple Point Principle (MPP) is reviewed. It demonstrates the existence of the two vacua into the SM. The Froggatt-Nielsen's prediction of the top-quark and Higgs masses is given in the assumption that there exist two degenerate vacua in the SM. This prediction was improved by the next order calculations. We also considered B.G. Sidharth's theory of cosmological constant based on the non-commutative geometry of the Planck scale space-time, what gives an extremely small DE density providing the accelerating expansion of the Universe. Theory of two degenerate vacua - the Planck scale phase and Electroweak (EW) phase - also is reviewed, topological defects in these vacua are investigated, also the Compton wavelength phase suggested by B.G. Sidharth was discussed. A general theory of the phase transition and the problem of the vacuum stability in the SM is reviewed. Assuming that the recently discovered at the LHC new resonance with mass $m_S \simeq 750$ GeV is a new scalar $S$ bound state $6t + 6\bar t$, earlier predicted by C.D. Froggatt, H.B. Nielsen and L.V. Laperashvili, we try to provide the vacuum stability in the SM and exact accuracy of the MPP.Comment: 37 pages and 7 figures. arXiv admin note: text overlap with arXiv:1601.03231; text overlap with arXiv:1302.2716 by other author

Generalized dual symmetry of nonabelian theories, monopoles and dyons

In the present talk we present an investigation of nonabelian SU(N) gauge theories, describing a system of fields with non--dual g and dual \tilde g charges and revealing the generalized dual symmetry. The Zwanziger type action is suggested. The renormalization group equations for pure nonabelian theories, in particular for pure SU(3)\times\widetilde{SU(3)} gauge theory (as an example) are analysed. We consider not only monopoles, but also dyons. The behaviour of the QCD total beta--function is investigated. It was shown that this beta--function is antisymmetric under the interchange \alpha\leftrightarrow\frac 1\alpha (here \alpha\equiv\alpha_s), and has zero ("fixed point") at \alpha = 1. Monopoles, or dyons, are responsible for the phase transition. Considering critical points at \alpha_1\approx 0.4 and \alpha_2\approx 2.5, we give an explanation of the freezing of \alpha_s.Comment: 15 pages, 5 figures, Presented at the 12th Lomonosov Conference on Elementary Particle Physics, Moscow State University, Moscow, 25-31 August, 200

Magnetic bipolar transistor

A magnetic bipolar transistor is a bipolar junction transistor with one or more magnetic regions, and/or with an externally injected nonequilibrium (source) spin. It is shown that electrical spin injection through the transistor is possible in the forward active regime. It is predicted that the current amplification of the transistor can be tuned by spin.Comment: 4 pages, 2 figure