429 research outputs found

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

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 $T_{c}$ Materials: An Impossibility'

We show that objections raised by Chakraverty $et$ $al$ (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 Ti$_{4}$O$_{7}$ Studied by Photoemission Spectroscopy

We have performed a photoemission study of Ti$_{4}$O$_{7}$ 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 Fe$_{3}$O$_{4}$, 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

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

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

The leptons are viewed as composite objects, exhibiting anomalous magnetic
moments and anomalous flavor-changing transition moments. The decay $\mu \to e
\gamma$ 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

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 $T_{SC}\to 0$ giving rise to a
metallic phase or $T>T_{SC}$. For repulsive interactions at $T\to 0$ 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 $|\frac{d\ln N(b)}{\ln b}|\ll 1$
one finds a fixed point $(D^*,\Gamma^*_2)$ in the plane $(D,\Gamma_2^{(s)})$.
($D\propto(K_F\ell)^{-1}$ is the disorder coupling constant, $\Gamma_2^{(s)}$
is the particle-hole triplet interaction, $b$ is the length scale and $N(b)$ is
the number of channels.) For weak disorder, $D<D^*$, one obtains a metallic
behavior with the resistance
$\rho(D,\Gamma_2^{(s)},T)=\rho(D,\Gamma_2^{(s)},T)\simeq
\rho^*f(\frac{D-D^*}{D^*}\frac{1}{T^{z\nu_1}})$
($\rho^*=\rho(D^*,\Gamma_2^*,1)$, $z=1$, and $\nu_1>1$) 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

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

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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