3,361 research outputs found
Supersymmetric Grand Unification and Lepton Universality in K-> l \nu Decays
Motivated by the prospects for an improved test of lepton universality in K
-> l \nu decays by the NA62 experiment at CERN, we study predictions for the
possible lepton non-universality in K -> l \nu decays in supersymmetric models.
Violations of \mu-e universality in this process may originate from mixing
effects in the right-handed slepton sector, providing a unique window into this
aspect of supersymmetric flavour physics in the large-\tan\beta region. Minimal
unification scenarios with universal soft supersymmetry-breaking terms at the
GUT scale would predict negligible violation of lepton universality. However,
lepton non-universality may be observable in non-minimal grand unified models
with higher-dimensional terms contributing to fermion masses, in which case
renormalization effects above the GUT scale may enhance the mixing among the
right-handed sleptons. This could leads to observable lepton non-universality
in K -> l \nu decays in specific regions of the parameter space with high \tan
\beta, large A terms and small charged Higgs boson mass. Observable
non-universality in K -> l \nu decays would be correlated with a large value of
BR(\tau -> e \gamma). The experimental upper limit on the electric dipole
moment of the electron could be reconciled with leptogenesis, if the latter
occurs at a relatively low scale, which would also alleviate the cosmological
gravitino problem. Even if lepton non-universality is not seen in the near
future, one may nevertheless obtain significant constraints on the model
parameters and unknown aspects of right-handed fermion and sfermion mixing.Comment: 19 pages, 3 figure
(Re)fashioning Biafra: identity, authorship and the politics of dress in half of a yellow sun and other narratives of the Nigeria-Biafra war
Chimamanda Ngozi Adichie’s second novel, Half of a Yellow (2006), is one in a long line of works by Nigerian authors to portray the Nigeria-Biafra War (1967-1970). While Adichie has stated that she wanted to make modern Nigeria aware of its history by writing the novel, the writer has also revealed that she drew from past literary portrayals to construct her narrative. In order to untangle the complex construction of Half of a Yellow Sun, this article explores the way the novel negotiates the literary legacy of Biafra through material fashion, which I argue elucidates this complex intertextuality. Furthermore, I contend that the novel draws attention to and critiques the way that understanding of Biafra has been dominated by novels written by male authors, and weaves threads of material fashion in order to offer a new way of negotiating Nigerian history
Implications on SUSY breaking mediation mechanisms from observing and the muon
We consider and the muon in various SUSY
breaking mediation mechanisms. If the decay is observed
at Tevatron Run II with a branching ratio larger than ,
the noscale supergravity (including the gaugino mediation), the gauge mediation
scenario with small number of messenger fields and low messenger scale, and a
class of anomaly mediation scenarios will be excluded, even if they can
accommodate a large muon . On the other hand, the minimal
supergravity scenario and similar mechanisms derived from string models can
accommodate this observation.Comment: 4 pages, 3 figure
All-sky Galactic radiation at 45 MHz and spectral index between 45 and 408 MHz
Aims: We study the Galactic large-scale synchrotron emission by generating a
reliable all-sky spectral index map and temperature map at 45 MHz. Methods: We
use our observations, the published all-sky map at 408 MHz, and a
bibliographical compilation to produce a map corrected for zero-level offset
and extragalactic contribution. Results: We present full sky maps of the
Galactic emission at 45 MHz and the Galactic spectral index between 45 and 408
MHz with an angular resolution of 5\degs. The spectral index varies between 2.1
and 2.7, reaching values below 2.5 at low latitude because of thermal free-free
absorption and its maximum in the zone next to the Northern Spur.Comment: A&A accepte
Direct detection of neutralino dark matter in supergravity
The direct detection of neutralino dark matter is analysed in general
supergravity scenarios, where non-universal soft scalar and gaugino masses can
be present. In particular, the theoretical predictions for the
neutralino-nucleon cross section are studied and compared with the sensitivity
of dark matter detectors. We take into account the most recent astrophysical
and experimental constraints on the parameter space, including the current
limit on B(Bs-> mu+ mu-). The latter puts severe limitations on the dark matter
scattering cross section, ruling out most of the regions that would be within
the reach of present experiments. We show how this constraint can be softened
with the help of appropriate choices of non-universal parameters which increase
the Higgsino composition of the lightest neutralino and minimise the chargino
contribution to the b->s transition.Comment: 27 pages, 22 figure
Evidence of the neuron-restrictive silencer factor (NRSF) interaction with Sp3 and its synergic repression to the mu opioid receptor (MOR) gene
Previously, we reported that the neuron-restrictive silencer element (NRSE) of mu opioid receptor (MOR) functions as a critical regulator to repress the MOR transcription in specific neuronal cells, depending on neuron-restriction silence factor (NRSF) expression levels [C.S.Kim, C.K.Hwang, H.S.Choi, K.Y.Song, P.Y.Law, L.N.Wei and H.H.Loh (2004) J. Biol. Chem., 279, 46464–46473]. Herein, we identify a conserved GC sequence next to NRSE region in the mouse MOR gene. The inhibition of Sp family factors binding to this GC box by mithramycin A led to a significant increase in the endogenous MOR transcription. In the co-immunoprecipitation experiment, NRSF interacted with the full-length Sp3 factor, but not with Sp1 or two short Sp3 isoforms. The sequence specific and functional binding by Sp3 at this GC box was confirmed by in vitro gel-shift assays using either in vitro translated proteins or nuclear extract, and by in vivo chromatin immunoprecipitation assays. Transient transfection assays showed that Sp3-binding site of the MOR gene is a functionally synergic repressor element with NRSE in NS20Y cells, but not in the NRSF negative PC12 cells. The results suggest that the synergic interaction between NRSF and Sp3 is required to negatively regulate MOR gene transcription and that transcription of MOR gene would be governed by the context of available transcription factors rather than by a master regulator
Testing Quarkonium Production with Photoproduced
I compute the leading color-octet contributions to the process within the non-relativistic QCD (NRQCD)
factorization formalism. In the color-singlet model, can only
be produced when the photon interacts through its structure function, while the
color-octet mechanism allows for production of via direct
photon-gluon fusion. Resolved photon processes can be easily be distinguished
from direct photon processes by examining the fraction of the incident photon
energy carried away by the in the event. Therefore, this process
provides a conclusive test of the color-octet mechanism.
production is particularly sensitive to the NRQCD matrix element which figures
prominently in the fragmentation production of at large in
hadron colliders. I also examine the predictions of the color evaporation model
(CEM) of quarkonium production and find that this process can easily
discriminate between the NRQCD factorization formalism and the CEM.Comment: uses Revtex, 12 pages, 4 EPS figures embedded using epsf.sty. Some
references have been added. Version accepted for publication in Phys. Rev.
Evo-devo of human adolescence: beyond disease models of early puberty
Despite substantial heritability in pubertal development, much variation remains to be explained, leaving room for the influence of environmental factors to adjust its phenotypic trajectory in the service of fitness goals. Utilizing evolutionary development biology (evo-devo), we examine adolescence as an evolutionary life-history stage in its developmental context. We show that the transition from the preceding stage of juvenility entails adaptive plasticity in response to energy resources, other environmental cues, social needs of adolescence and maturation toward youth and adulthood. Using the evolutionary theory of socialization, we show that familial psychosocial stress fosters a fast life history and reproductive strategy rather than early maturation being just a risk factor for aggression and delinquency. Here we explore implications of an evolutionary-developmental-endocrinological-anthropological framework for theory building, while illuminating new directions for research
MSSM Higgs sector CP violation at photon colliders: Revisited
We present a comprehensive analysis on the MSSM Higgs sector CP violation at
photon colliders including the chargino contributions as well as the
contributions of other charged particles. The chargino loop contributions can
be important for the would-be CP odd Higgs production at photon colliders.
Polarization asymmetries are indispensable in determining the CP properties of
neutral Higgs bosons.Comment: 24 pages, 40 figure
A critical role for astrocytes in hypercapnic vasodilation in brain
Cerebral blood flow (CBF) is controlled by arterial blood pressure, arterial CO2, arterial O2, and brain activity and is largely constant in the awake state. Although small changes in arterial CO2 are particularly potent to change CBF (1 mmHg variation in arterial CO2 changes CBF by 3-4%), the coupling mechanism is incompletely understood. We tested the hypothesis that astrocytic prostaglandin E2 (PgE2) plays a key role for cerebrovascular CO2 reactivity and that preserved synthesis of glutathione is essential for the full development of this response.
We combined two-photon imaging microscopy in brain slices with in vivo work in rats and C57Bl/6J mice to examine the hemodynamic responses to CO2 and somatosensory stimulation before and after inhibition of astrocytic glutathione and PgE2 synthesis. We demonstrate that hypercapnia (increased CO2) evokes an increase in astrocyte [Ca2+]i and stimulates COX-1 activity. The enzyme downstream of COX-1 that synthesizes PgE2 (microsomal prostaglandin E synthase-1) depends critically for its vasodilator activity on the level of glutathione in the brain. We show that when glutathione levels are reduced, astrocyte calcium-evoked release of PgE2 is decreased and vasodilation triggered by astrocyte [Ca2+]i in vitro and by hypercapnia in vivo is inhibited.
Astrocyte synthetic pathways, dependent on glutathione, are involved in cerebrovascular reactivity to CO2. Reductions in glutathione levels in ageing, stroke or schizophrenia could lead to dysfunctional regulation of CBF and subsequent neuronal damage
- …