1,354 research outputs found
Gaugino Mass without Singlets
In models with dynamical supersymmetry breaking in the hidden sector, the
gaugino masses in the observable sector have been believed to be extremely
suppressed (below 1 keV), unless there is a gauge singlet in the hidden sector
with specific couplings to the observable sector gauge multiplets. We point out
that there is a pure supergravity contribution to gaugino masses at the quantum
level arising from the superconformal anomaly. Our results are valid to all
orders in perturbation theory and are related to the `exact' beta functions for
soft terms. There is also an anomaly contribution to the A terms proportional
to the beta function of the corresponding Yukawa coupling. The gaugino masses
are proportional to the corresponding gauge beta functions, and so do not
satisfy the usual GUT relations.Comment: 25 pages, references added, typos and grammar correcte
Hidden particle production at the ILC
In a class of new physics models, new physics sector is completely or partly
hidden, namely, singlet under the Standard Model (SM) gauge group. Hidden
fields included in such new physics models communicate with the Standard Model
sector through higher dimensional operators. If a cutoff lies in the TeV range,
such hidden fields can be produced at future colliders. We consider a scalar
filed as an example of the hidden fields. Collider phenomenology on this hidden
scalar is similar to that of the SM Higgs boson, but there are several features
quite different from those of the Higgs boson. We investigate productions of
the hidden scalar at the International Linear Collider (ILC) and study the
feasibility of its measurements, in particular, how well the ILC distinguishes
the scalar from the Higgs boson, through realistic Monte Carlo simulations.Comment: the version to be published in PR
Molecular signatures distinguish human central memory from effector memory CD8 T cell subsets
Abstract
Memory T cells are heterogeneous in terms of their phenotype and functional properties. We investigated the molecular profiles of human CD8 naive central memory (TCM), effector memory (TEM), and effector memory RA (TEMRA) T cells using gene expression microarrays and phospho-protein-specific intracellular flow cytometry. We demonstrate that TCM have a gene expression and cytokine signaling signature that lies between that of naive and TEM or TEMRA cells, whereas TEM and TEMRA are closely related. Our data define the molecular basis for the different functional properties of central and effector memory subsets. We show that TEM and TEMRA cells strongly express genes with known importance in CD8 T cell effector function. In contrast, TCM are characterized by high basal and cytokine-induced STAT5 phosphorylation, reflecting their capacity for self-renewal. Altogether, our results distinguish TCM and TEM/TEMRA at the molecular level and are consistent with the concept that TCM represent memory stem cells.</jats:p
More Visible Effects of the Hidden Sector
There is a growing appreciation that hidden sector dynamics may affect the
supersymmetry breaking parameters in the visible sector (supersymmetric
standard model), especially when the dynamics is strong and superconformal. We
point out that there are effects that have not been previously discussed in the
literature. For example, the gaugino masses are suppressed relative to the
gravitino mass. We discuss their implications in the context of various
mediation mechanisms. The issues discussed include anomaly mediation with
singlets, the mu (B mu) problem in gauge and gaugino mediation, and distinct
mass spectra for the superparticles that have not been previously considered.Comment: 25 pages; small clarifications and corrections, version to appear in
Phys. Rev.
Pulse shape effects on photon-photon interactions in non-linear optical quantum gates
Ideally, strong non-linearities could be used to implement quantum gates for
photonic qubits by well controlled two photon interactions. However, the
dependence of the non-linear interaction on frequency and time makes it
difficult to preserve a coherent pulse shape that could justify a single mode
model for the time-frequency degree of freedom of the photons. In this paper,
we analyze the problem of temporal multi-mode effects by considering the pulse
shape of the average output field obtained from a coherent input pulse. It is
shown that a significant part of the two photon state transformation can be
derived from this semi-classical description of the optical non-linearity. The
effect of a non-linear system on a two photon state can then be determined from
the density matrix dynamics of the coherently driven system using input-output
theory. As an example, the resonant non-linearity of a single two level atom is
characterized. The results indicate that the most efficient non-linear effect
may not be the widely studied single mode phase shift, but the transfer of one
of the photons to an orthogonal mode distinguished by its temporal and spectral
properties.Comment: 11 pages, including 5 figures and 1 table; improved figures and
additional discussion on relation to entangled two photon wavefunctions
dynamics. Final version for publication in Phys. Rev.
Human naive CD8 T cells down-regulate expression of the WNT pathway transcription factors lymphoid enhancer binding factor 1 and transcription factor 7 (T cell factor-1) following antigen encounter in vitro and in vivo
Abstract
The transcription factors lymphoid enhancer binding factor 1 (LEF1) and transcription factor 7 (TCF7) (T cell factor-1 (TCF-1)) are downstream effectors of the WNT signaling pathway, which is a critical regulator of T cell development in the thymus. In this study, we show that LEF1 and TCF7 (TCF-1) are not only expressed in thymocytes, but also in mature T cells. Our data demonstrate that Ag encounter in vivo and engagement of the TCR or IL-15 receptor in vitro leads to the down-regulation of LEF1 and TCF7 (TCF-1) expression in human naive CD8 T cells. We further show that resting T cells preferentially express inhibitory LEF1 and TCF7 (TCF-1) isoforms and that T cell activation changes the isoform balance in favor of stimulatory TCF7 (TCF-1) isoforms. Altogether, our study suggests that proteins involved in the WNT signaling pathway not only regulate T cell development, but also peripheral T cell differentiation.</jats:p
Shock-Wave Heating Model for Chondrule Formation: Prevention of Isotopic Fractionation
Chondrules are considered to have much information on dust particles and
processes in the solar nebula. It is naturally expected that protoplanetary
disks observed in present star forming regions have similar dust particles and
processes, so study of chondrule formation may provide us great information on
the formation of the planetary systems.
Evaporation during chondrule melting may have resulted in depletion of
volatile elements in chondrules. However, no evidence for a large degree of
heavy-isotope enrichment has been reported in chondrules. In order to meet this
observed constraint, the rapid heating rate at temperatures below the silicate
solidus is required to suppress the isotopic fractionation.
We have developed a new shock-wave heating model taking into account the
radiative transfer of the dust thermal continuum emission and the line emission
of gas molecules and calculated the thermal history of chondrules. We have
found that optically-thin shock waves for the thermal continuum emission from
dust particles can meet the rapid heating constraint, because the dust thermal
emission does not keep the dust particles high temperature for a long time in
the pre-shock region and dust particles are abruptly heated by the gas drag
heating in the post-shock region. We have also derived the upper limit of
optical depth of the pre-shock region using the radiative diffusion
approximation, above which the rapid heating constraint is not satisfied. It is
about 1 - 10.Comment: 58 pages, including 5 tables and 15 figures, accepted for publication
in The Astrophysical Journa
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