505 research outputs found
Mass-Enhanced Fermi Liquid Ground State in NaCoO
Magnetic, transport, and specific heat measurements have been performed on
layered metallic oxide NaCoO as a function of temperature .
Below a characteristic temperature =3040 K, electrical resistivity
shows a metallic conductivity with a behavior and magnetic susceptibility
deviates from the Curie-Weiss behavior showing a broad peak at 14 K. The
electronic specific heat coefficient is 60 mJ/molK at 2 K.
No evidence for magnetic ordering is found. These behaviors suggest the
formation of mass-enhanced Fermi liquid ground state analogous to that in
-electron heavy fermion compound LiVO.Comment: 4 pages, 4 figures, to be published in Phys. Rev. B 69 (2004
Role of mitochondrial raft-like microdomains in the regulation of cell apoptosis
Lipid rafts are envisaged as lateral assemblies of specific lipids and proteins that dissociate and associate rapidly and form functional clusters in cell membranes. These structural platforms are not confined to the plasma membrane; indeed lipid microdomains are similarly formed at subcellular organelles, which include endoplasmic reticulum, Golgi and mitochondria, named raft-like microdomains. In addition, some components of raft-like microdomains are present within ER-mitochondria associated membranes. This review is focused on the role of mitochondrial raft-like microdomains in the regulation of cell apoptosis, since these microdomains may represent preferential sites where key reactions take place, regulating mitochondria hyperpolarization, fission-associated changes, megapore formation and release of apoptogenic factors. These structural platforms appear to modulate cytoplasmic pathways switching cell fate towards cell survival or death. Main insights on this issue derive from some pathological conditions in which alterations of microdomains structure or function can lead to severe alterations of cell activity and life span. In the light of the role played by raft-like microdomains to integrate apoptotic signals and in regulating mitochondrial dynamics, it is conceivable that these membrane structures may play a role in the mitochondrial alterations observed in some of the most common human neurodegenerative diseases, such as Amyotrophic lateral sclerosis, Huntington's chorea and prion-related diseases. These findings introduce an additional task for identifying new molecular target(s) of pharmacological agents in these pathologies
Measurement of tau polarization in e+ e- annihilation at sqrt{s}=58 GeV
The polarization of tau leptons in the reaction e+ e- --> tau+ tau- has been
measured using a e+e- collider, TRISTAN, at the center-of-mass energy of 58
GeV. From the kinematical distributions of daughter particles in tau --> e nu
nu-bar, mu nu nu-bar, rho nu or pi(K) nu decays, the average polarization of
tau- and its forward-backward asymmetry have been evaluated to be 0.012 +-
0.058 and 0.029 +- 0.057, respectively.Comment: 18 pages, 5 figure
Observation of Large CP Violation in the Neutral B Meson System
We present a measurement of the Standard Model CP violation parameter sin
2phi_1 based on a 29.1 fb^{-1} data sample collected at the Upsilon(4S)
resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.
One neutral B meson is fully reconstructed as a J/psi Ks, psi(2S) Ks, chi_c1
Ks, eta_c Ks, J/psi K_L or J/psi K^{*0} decay and the flavor of the
accompanying B meson is identified from its decay products. From the asymmetry
in the distribution of the time intervals between the two B meson decay points,
we determine sin 2phi_1 = 0.99 +- 0.14(stat) +- 0.06(syst). We conclude that we
have observed CP violation in the neutral B meson system.Comment: 4 figures, to appear in Phys. Rev. Letter
A Measurement of Lifetime Difference in Meson Decays
We report a measurement of the - mixing parameter
using 23.4 fb of data collected near the (4S) resonance with
the Belle detector at KEKB. is measured from the lifetime difference
of mesons decaying into the state and the CP even eigenstate
. We find , where
the first error is statistical and the second systematic, corresponding to a
95% confidence interval .Comment: 10 pages, 3 figure
Proton-Antiproton Pair Production in Two-Photon Collisions at LEP
The reaction e^+e^- -> e^+e^- proton antiproton is studied with the L3
detector at LEP. The analysis is based on data collected at e^+e^-
center-of-mass energies from 183 GeV to 209 GeV, corresponding to an integrated
luminosity of 667 pb^-1. The gamma gamma -> proton antiproton differential
cross section is measured in the range of the two-photon center-of-mass energy
from 2.1 GeV to 4.5 GeV. The results are compared to the predictions of the
three-quark and quark-diquark models
Search for Direct CP Violation in B -> K pi Decays
We search for direct CP violation in flavor specific B -> K pi decays by
measuring the rate asymmetry between charge conjugate modes. The search is
performed on a data sample of 11.1 million B B bar events recorded on the
Upsilon(4S) resonance by the Belle experiment at KEKB. We measure 90%
confidence intervals in the partial rate asymmetry A_CP of -0.25 < A_CP(K-/+
pi+/-) < 0.37, -0.40 < A_CP(K-/+ pi^0) < 0.36, and -0.53 < A_CP(K^0 pi-/+) <
0.82. By combining the K-/+ pi+/- and K-/+ pi^0 final states, we conclude that
-0.22 < A_CP[K-/+(pi+/- + pi^0)] < 0.25 at the 90% confidence level.Comment: Submitted to PRD Rapid Communication
Study of CP-Violating Asymmetries in B0 -> pi+pi- Decays
We present a measurement of CP-violating asymmetries in B0 -> pi+pi- decays
based on a 41.8 fb-1 data sample collected at the Upsilon(4S) resonance with
the Belle detector at the KEKB asymmetric-energy e+e- collider. We fully
reconstruct one neutral B meson as a B0 -> pi+pi- CP eigenstate and identify
the flavor of the accompanying B meson from its decay products. From the
asymmetry in the distribution of the time intervals between the two B meson
decay points, we obtain the CP-violating asymmetry parameters Spipi = -1.21
+0.38/-0.27(stat) +0.16/-0.13(syst) and Apipi = +0.94 +0.25/-0.31(stat) +/-
0.09(syst).Comment: 9 pages, 2 figures, accepted for publication in Physical Review
Letter
Observation of Cabibbo-suppressed and W-exchange Lambda_c^+ baryon decays
We present measurements of the Cabibbo-suppressed decays Lambda_c^+ -->
Lambda0 K+ and Lambda_c^+ --> Sigma0 K+ (both first observations), Lambda_c^+
--> Sigma+ K+ pi- (seen with large statistics for the first time), Lambda_c^+
--> p K+ K- and Lambda_c^+ --> p phi (measured with improved accuracy).
Improved branching ratio measurements for the decays Lambda_c^+ --> Sigma+ K+
K- and Lambda_c^+ --> Sigma+ phi, which are attributed to W-exchange diagrams,
are shown. We also present the first evidence for Lambda_c^+ --> Xi(1690)^0 K+
and set an upper limit on the non-resonant decay Lambda_c^+ --> Sigma+ K+ K-.
This analysis was performed using 32.6 fb^{-1} of data collected by the Belle
detector at the asymmetric e+ e- collider KEKB.Comment: Submitted to Phys. Lett. B. v2: A small correction to the Authorlist
was made. An earlier version of this analysis was released as
BELLE-CONF-0130, hep-ex/010800
Observation of Cabibbo suppressed decays at Belle
Cabibbo-suppressed decays using a 10.4 fb data
sample accumulated at the resonance with the Belle detector at
the KEKB storage ring. The high-momentum particle identification
system of Belle is used to isolate signals for , ,
and from the decay processes which
have much larger branching fractions. We report ratios of Cabibbo-suppressed to
Cabibbo-favored branching fractions of: ; ; ; and
. The first error is statistical and the second is systematic.
These are the first reported observations of the , and
decay processes.Comment: LaTeX, 12 pages, 2 figure
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