185 research outputs found
Evidence that the Y(4660) is a f_0(980)psi' bound state
We demonstrate that the experimental information currently available for the
Y(4660) is consistent with its being a f_0(980)psi' molecule. Possible
experimental tests of our hypothesis are presented.Comment: 4 pages, 3 figure
Exploring the intrinsic Lorentz-violating parameters at DUNE
Neutrinos can push our search for new physics to a whole new level. What makes them so hard to be detected, what allows them to travel humongous distances without being stopped or deflected allows to amplify Planck suppressed effects (or effects of comparable size) to a level that we can measure or bound in DUNE. In this work we analyze the sensitivity of DUNE to CPT and Lorentz- violating interactions in a framework that allows a straightforward extrapolation of the bounds obtained to any phenomenological modification of the dispersion relation of neutrinos
SUSY S4 x SU(5) revisited
Following the recent results from Daya Bay and RENO, which measure the lepton
mixing angle theta^l_13 ~ 0.15, we revisit a supersymmetric S4 x SU(5) model,
which predicts tri-bimaximal (TB) mixing in the neutrino sector with theta^l_13
being too small in its original version. We show that introducing one
additional S4 singlet flavon into the model gives rise to a sizable theta^l_13
via an operator which leads to the breaking of one of the two Z2 symmetries
preserved in the neutrino sector at leading order. The results of the original
model for fermion masses, quark mixing and the solar mixing angle are
maintained to good precision. The atmospheric and solar mixing angle deviations
from TB mixing are subject to simple sum rule bounds.Comment: 15 pages, 1 figur
Trimaximal neutrino mixing from vacuum alignment in A4 and S4 models
Recent T2K results indicate a sizeable reactor angle theta_13 which would
rule out exact tri-bimaximal lepton mixing. We study the vacuum alignment of
the Altarelli-Feruglio A4 family symmetry model including additional flavons in
the 1' and 1" representations and show that it leads to trimaximal mixing in
which the second column of the lepton mixing matrix consists of the column
vector (1,1,1)^T/sqrt{3}, with a potentially large reactor angle. In order to
limit the reactor angle and control the higher order corrections, we propose a
renormalisable S4 model in which the 1' and 1" flavons of A4 are unified into a
doublet of S4 which is spontaneously broken to A4 by a flavon which enters the
neutrino sector at higher order. We study the vacuum alignment in the S4 model
and show that it predicts accurate trimaximal mixing with approximate
tri-bimaximal mixing, leading to a new mixing sum rule testable in future
neutrino experiments. Both A4 and S4 models preserve form dominance and hence
predict zero leptogenesis, up to renormalisation group corrections.Comment: 24 pages, 2 figures, version to be published in JHE
STRONG SUPERSYMMETRIC QUANTUM EFFECTS ON THE TOP QUARK WIDTH
We compute the one-loop supersymmetric QCD quantum effects on the width
of the canonical main decay of the top quark
within the framework of the MSSM. The corrections can be of either sign
depending on whether the stop squark mass is above or below the top quark decay
threshold into stop and gluino .
For above that threshold, the corrections are negative and can
be of the same order (and go in the same direction) as the ordinary QCD
corrections, even for stop and gluino masses of . Since the
electroweak supersymmetric quantum effects turn out to be also of the same sign
and could be of the same order of magnitude, the total MSSM correction to the
top quark width could potentially result in a rather large
reduction of far beyond the conventional QCD
expectations.Comment: 11 page
QCD Corrections to B -> X_{d,s} nu nubar, B_{d,s} -> l^+l^-, K -> pi nu nubar and K_L -> mu^+ mu^- in the MSSM
We compute for the first time QCD corrections to the rare decays B -> X_{d,s}
nu nubar, B_{d,s} -> l^+ l^-, K -> pi nu nubar and K_L -> mu^+ mu^-, where l=e
or mu, in the context of a supersymmetric extension of the Standard Model (SM)
with minimal flavour violation and new operators, in addition to those present
in the SM. Assuming that the gluino is heavy, we consider an effective theory
which consists of charged and neutral Higgs particles, charginos and squarks.
We evaluate the QCD corrections to box and Z^0-penguin diagrams with top-quark,
charged Higgs boson, chargino and squark exchanges, as well as to neutral Higgs
boson penguin diagrams. We provide a compendium of analytic formulae for the
Wilson coefficients, which are valid for arbitrary values of tan(beta) (the
ratio of the vacuum expectation values of the two Higgs fields) except for the
case of the neutral Higgs-boson contributions. These contributions have been
obtained at large tan(beta), which may compensate for the inevitable
suppression by the masses of the light leptons in decays based on the b -> s
(d) l^+ l^- transition. We investigate the dependence of the various branching
ratios on the renormalization scale mu, which is the main theoretical
uncertainty in the short-distance calculation. We find that the mu dependence
of the branching ratios is considerably reduced once the QCD corrections are
taken into account. The contributions of new operators are found to be dominant
at large tan(beta) in B_{d,s} -> mu^+ mu^- while they are subleading in B ->
X_{d,s} nu nubar and completely negligible in kaon decays.Comment: 47 pages, 9 figures; version to appear in Nucl. Phys.
Planet Hunters. VIII. Characterization of 41 Long-Period Exoplanet Candidates from Kepler Archival Data
The census of exoplanets is incomplete for orbital distances larger than 1
AU. Here, we present 41 long-period planet candidates in 38 systems identified
by Planet Hunters based on Kepler archival data (Q0-Q17). Among them, 17
exhibit only one transit, 14 have two visible transits and 10 have more than
three visible transits. For planet candidates with only one visible transit, we
estimate their orbital periods based on transit duration and host star
properties. The majority of the planet candidates in this work (75%) have
orbital periods that correspond to distances of 1-3 AU from their host stars.
We conduct follow-up imaging and spectroscopic observations to validate and
characterize planet host stars. In total, we obtain adaptive optics images for
33 stars to search for possible blending sources. Six stars have stellar
companions within 4". We obtain high-resolution spectra for 6 stars to
determine their physical properties. Stellar properties for other stars are
obtained from the NASA Exoplanet Archive and the Kepler Stellar Catalog by
Huber et al. (2014). We validate 7 planet candidates that have planet
confidence over 0.997 (3-{\sigma} level). These validated planets include 3
single-transit planets (KIC-3558849b, KIC-5951458b, and KIC-8540376c), 3
planets with double transits (KIC-8540376b, KIC-9663113b, and KIC-10525077b),
and 1 planet with 4 transits (KIC-5437945b). This work provides assessment
regarding the existence of planets at wide separations and the associated false
positive rate for transiting observation (17%-33%). More than half of the
long-period planets with at least three transits in this paper exhibit transit
timing variations up to 41 hours, which suggest additional components that
dynamically interact with the transiting planet candidates. The nature of these
components can be determined by follow-up radial velocity and transit
observations.Comment: Published on ApJ, 815, 127 Notations of validated planets are changed
in accordance with naming convention of NASA Exoplanet Archiv
Purified F-ATP synthase forms a Ca2+-dependent high-conductance channel matching the mitochondrial permeability transition pore
The molecular identity of the mitochondrial megachannel (MMC)/permeability transition pore (PTP), a key effector of cell death, remains controversial. By combining highly purified, fully active bovine F-ATP synthase with preformed liposomes we show that Ca2+ dissipates the H+ gradient generated by ATP hydrolysis. After incorporation of the same preparation into planar lipid bilayers Ca2+ elicits currents matching those of the MMC/PTP. Currents were fully reversible, were stabilized by benzodiazepine 423, a ligand of the OSCP subunit of F-ATP synthase that activates the MMC/PTP, and were inhibited by Mg2+ and adenine nucleotides, which also inhibit the PTP. Channel activity was insensitive to inhibitors of the adenine nucleotide translocase (ANT) and of the voltage-dependent anion channel (VDAC). Native gel-purified oligomers and dimers, but not monomers, gave rise to channel activity. These findings resolve the long-standing mystery of the MMC/PTP and demonstrate that Ca2+ can transform the energy-conserving F-ATP synthase into an energy-dissipating device
Upper Bounds on Rare K and B Decays from Minimal Flavour Violation
We study the branching ratios of rare K and B decays in models with minimal
flavour violation, using the presently available information from the universal
unitarity triangle analysis and from the measurements of Br(B -> X_s gamma),
Br(B -> X_s l^+l^-) and Br(K^+ -> pi^+ nu nubar). We find the following upper
bounds: Br(K^+ -> pi^+ nu nubar) pi^0 nu nubar)< 4.6
10^{-11}, Br(K_L -> mu mubar)_{SD} X_s nu nubar)< 5.2
10^{-5}, Br(B -> X_d nu nubar) mu mubar)< 7.4 10^{-9},
Br(B_d -> mu mubar)< 2.2 10^{-10} at 95 % probability. We analyze in detail
various possible scenarios with positive or negative interference of Standard
Model and New Physics contributions, and show how an improvement of
experimental data corresponding to the projected 2010 B factory integrated
luminosities will allow to disentangle and test these different possibilities.
Finally, anticipating that subsequently the leading role in constraining this
kind of new physics will be taken over by the rare decays K^+ -> pi^+ nu nubar,
K_L -> pi^0 nu nubar and B_{s,d} -> mu mubar, that are dominated by the Z^0
-penguin function C, we also present plots for several branching ratios as
functions of C . We point out an interesting triple correlation between K^+ ->
pi^+ nu nubar, B -> X_s gamma and B -> X_s l^+l^- present in MFV models.Comment: 26 pages, 12 figure
The FERM protein EPB41L5 regulates actomyosin contractility and focal adhesion formation to maintain the kidney filtration barrier
Podocytes form the outer part of the glomerular filter, where they have to withstand enormous transcapillary filtration forces driving glomerular filtration. Detachment of podocytes from the glomerular basement membrane precedes most glomerular diseases. However, little is known about the regulation of podocyte adhesion in vivo. Thus, we systematically screened for podocyte-specific focal adhesome (FA) components, using genetic reporter models in combination with iTRAQ-based mass spectrometry. This approach led to the identification of FERM domain protein EPB41L5 as a highly enriched podocyte-specific FA component in vivo. Genetic deletion of Epb41l5 resulted in severe proteinuria, detachment of podocytes, and development of focal segmental glomerulosclerosis. Remarkably, by binding and recruiting the RhoGEF ARGHEF18 to the leading edge, EPB41L5 directly controls actomyosin contractility and subsequent maturation of focal adhesions, cell spreading, and migration. Furthermore, EPB41L5 controls matrix-dependent outside-in signaling by regulating the focal adhesome composition. Thus, by linking extracellular matrix sensing and signaling, focal adhesion maturation, and actomyosin activation EPB41L5 ensures the mechanical stability required for podocytes at the kidney filtration barrier. Finally, a diminution of EPB41L5-dependent signaling programs appears to be a common theme of podocyte disease, and therefore offers unexpected interventional therapeutic strategies to prevent podocyte loss and kidney disease progression
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