428 research outputs found

    Chargino contributions to the CP asymmetry in B -> Phi K(S) decay

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    We perform a model independent analysis of the chargino contributions to the CP asymmetry in B -> Phi K(S) process. We use the mass insertion approximation method generalized by including the possibility of a light right-stop. We find that the dominant effect is given by the contributions of the mass insertions deltaU_LL(32) and deltaU_RL(32) to the Wilson coefficient of the chromomagnetic operator. By considering both these contributions simultaneously, the CP asymmetry in B -> Phi K(S) process is significantly reduced and negative values, which are within the 1-sigma experimental range and satisfy the b -> s gamma constraints, can be obtained.Comment: 14 pages, LaTeX, 3.eps Figure

    Comment on `Experimental and Theoretical Constraints of Bipolaronic Superconductivity in High TcT_{c} Materials: An Impossibility'

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    We show that objections raised by Chakraverty etet alal (Phys. Rev. Lett. 81, 433 (1998)) to the bipolaron model of superconducting cuprates are the result of an incorrect approximation for the bipolaron energy spectrum and misuse of the bipolaron theory. The consideration, which takes into account the multiband energy structure of bipolarons and the unscreened electron-phonon interaction clearly indicates that cuprates are in the Bose-Einstein condensation regime with mobile charged bosons.Comment: 1 page, no figure

    Disorder Effects in the Bipolaron System Ti4_{4}O7_{7} Studied by Photoemission Spectroscopy

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    We have performed a photoemission study of Ti4_{4}O7_{7} around its two transition temperatures so as to cover the metallic, high-temperature insulating (bipolaron-liquid), and low-temperature insulating (bipolaron-crystal) phases. While the spectra of the low-temperature insulating phase show a finite gap at the Fermi level, the spectra of the high-temperature insulating phase are gapless, which is interpreted as a soft Coulomb gap due to dynamical disorder. We suggest that the spectra of the high-temperature disordered phase of Fe3_{3}O4_{4}, which exhibits a charge order-disorder transition (Verwey transition), can be interpreted in terms of a Coulomb gap.Comment: 4 pages, 3 epsf figures embedde

    Dendritic Cells Cross-Present Immunogenic Lentivector-Encoded Antigen from Transduced Cells to Prime Functional T Cell Immunity

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    Recombinant lentiviral vectors (LVs) are highly effective vaccination vehicles that elicit protective T cell immunity in disease models. Dendritic cells (DCs) acquire antigen at sites of vaccination and migrate to draining lymph nodes, where they prime vaccine-specific T cells. The potency with which LVs activate CD8+ T cell immunity has been attributed to the transduction of DCs at the immunization site and durable presentation of LV-encoded antigens. However, it is not known how LV-encoded antigens continue to be presented to T cells once directly transduced DCs have turned over. Here, we report that LV-encoded antigen is efficiently cross-presented by DCs in vitro. We have further exploited the temporal depletion of DCs in the murine CD11c.DTR (diphtheria toxin receptor) model to demonstrate that repopulating DCs that were absent at the time of immunization cross-present LV-encoded antigen to T cells in vivo. Indirect presentation of antigen from transduced cells by DCs is sufficient to prime functional effector T cells that control tumor growth. These data suggest that DCs cross-present immunogenic antigen from LV-transduced cells, thereby facilitating prolonged activation of T cells in the absence of circulating LV particles. These are findings that may impact on the future design of LV vaccination strategies

    Remote monitoring of off-grid renewable energy case studies in rural Malawi, Zambia, and Gambia

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    Increased understanding of off-grid renewable energy technology (RET) performance can assist in improving sustainability of such systems. The technologies for remote monitoring of RET deployments in developing countries are promising with various configurations and usages being tested. Recent applications of remote monitoring technologies in Malawi, Gambia, and Zambia are presented along with their respective strengths and weaknesses. The potential for remote monitoring applications to improve sustainability of off-grid RET is explored along with some theoretical directions of the technologies

    The anomalous magnetic moment of the muon and radiative lepton decays

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    The leptons are viewed as composite objects, exhibiting anomalous magnetic moments and anomalous flavor-changing transition moments. The decay Ό→eÎł\mu \to e \gamma is expected to occur with a branching ratio of the same order as the present experimental limit.Comment: 5 page

    Quantum Criticality at the Metal Insulator Transition

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    We introduce a new method to analysis the many-body problem with disorder. The method is an extension of the real space renormalization group based on the operator product expansion. We consider the problem in the presence of interaction, large elastic mean free path, and finite temperatures. As a result scaling is stopped either by temperature or the length scale set by the diverging many-body length scale (superconductivity). Due to disorder a superconducting instability might take place at TSC→0T_{SC}\to 0 giving rise to a metallic phase or T>TSCT>T_{SC}. For repulsive interactions at T→0T\to 0 we flow towards the localized phase which is analized within the diffusive Finkelstein theory. For finite temperatures with strong repulsive backward interactions and non-spherical Fermi surfaces characterized by ∣dln⁥N(b)ln⁥b∣â‰Ș1|\frac{d\ln N(b)}{\ln b}|\ll 1 one finds a fixed point (D∗,Γ2∗)(D^*,\Gamma^*_2) in the plane (D,Γ2(s))(D,\Gamma_2^{(s)}). (D∝(KFℓ)−1D\propto(K_F\ell)^{-1} is the disorder coupling constant, Γ2(s)\Gamma_2^{(s)} is the particle-hole triplet interaction, bb is the length scale and N(b)N(b) is the number of channels.) For weak disorder, D<D∗D<D^*, one obtains a metallic behavior with the resistance ρ(D,Γ2(s),T)=ρ(D,Γ2(s),T)≃ρ∗f(D−D∗D∗1TzÎœ1)\rho(D,\Gamma_2^{(s)},T)=\rho(D,\Gamma_2^{(s)},T)\simeq \rho^*f(\frac{D-D^*}{D^*}\frac{1}{T^{z\nu_1}}) (ρ∗=ρ(D∗,Γ2∗,1)\rho^*=\rho(D^*,\Gamma_2^*,1), z=1z=1, and Îœ1>1\nu_1>1) in good agreement with the experiments.Comment: 35 pages, Revte

    Supersymmetric contributions to the CP asymmetry of the B --> phi K and B --> eta' K

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    We analyse the CP asymmetry of the B --> phi K and B --> eta' K processes in general supersymmetric models. We consider both gluino and chargino exchanges in a model independent way by using the mass insertion approximation method. We adopt the QCD factorization method for evaluating the corresponding hadronic matrix elements. We show that chromomagnetic type of operator may play an important role in accounting for the deviation of the mixing CP asymmetry between B --> phi K and B --> J/psi K processes observed by Belle and BaBar experiments. We also show that due to the different parity in the final states of these processes, their supersymmetric contributions from the R-sector have an opposite sign, which naturally explain the large deviation between their asymmetries.Comment: Invited review article for Mod. Phys. Lett. A. 12 pages, 5 figures. 2 refs. adde

    Supersymmetric contributions to B -> D K and the determination of angle \gamma

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    We analyze supersymmetric contributions to B^- -> D^0 K^- and B^- ->\bar{D}^0 K^- processes. We investigate the possibility that supersymmetric CP violating phases can affect our determination for the angle \gamma in the unitary triangle of Cabibbo-Kobayashi-Maskaw mixing matrix. We calculate the gluino and chargino contributions to b--> u(\bar{c}s) and b-->c(\bar{u}s) transitions in a model independent way by using the mass insertion approximation method. We also revise the D^0 - \bar{D}^0 mixing constraints on the mass insertions between the first and second generations of the up sector. We emphasize that in case of negligible D^0 -\bar{D}^0 mixing, one should consider simultaneous contributions from more than one mass insertion in order to be able to obtain the CP asymmetries of these processes within their 1\sigma experimental range. However, with a large D^0-\bar{D}^0 mixing, one finds a significant deviation between the two asymmetries and it becomes natural to have them of order the central values of their experimental measurements.Comment: 20 page
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