252 research outputs found
Measurement of the wrong-sign decays D0 -> K+ pi- pi0 and D0 -> K+ pi- pi+ pi-, and search for CP violation
Using 281 fb^-1 of data from the Belle experiment recorded at or near the
Upsilon(4S) resonance, we have measured the rates of the ``wrong-sign'' decays
D0 -> K+ pi- pi0 and D0 -> K+ pi- pi+ pi- relative to those of the
Cabibbo-favored decays D0 -> K- pi+ pi0 and D0 -> K- pi+ pi+ pi-. These
wrong-sign decays proceed via a doubly Cabibbo-suppressed amplitude or via
D0-D0bar mixing; the latter has not yet been observed. We obtain
R_WS(Kpipi0)=[0.229 +/-0.017(stat.) +0.013-0.009(sys.)]% and R_WS(K3pi)=[0.320
+/-0.019(stat.) +0.018-0.013(sys.)]%. The CP asymmetries are measured to be
-0.006 +/- 0.053 and -0.018 +/- 0.044 for the K+ pi- pi0 and K+ pi- pi+ pi-
final states, respectively.Comment: 10 pages, 3 figures, submitted to PRL, Lepton-Photon 2005 Conference
in Uppsala, Sweden and HEP2005 Europhysics Conference in Lisboa, Portuga
Search for the Lepton-Flavor-Violating Decay at Belle
We have searched for the Lepton Flavor Violating decay using a data sample of 84.3 fb accumulated with the Belle detector
at KEK. The -meson was detected through the decay modes: and . No signal candidates are found, and we
obtain an upper limit for the branching fraction at the 90% confidence level.Comment: Submitted to Phys.Rev.Let
Topological thermal Hall effect due to Weyl magnons
We present the first theoretical evidence of zero magnetic field topological
(anomalous) thermal Hall effect due to Weyl magnons. Here, we consider Weyl
magnons in stacked noncoplanar frustrated kagom\'e antiferromagnets recently
proposed by Owerre, [arXiv:1708.04240]. The Weyl magnons in this system result
from macroscopically broken time-reversal symmetry by the scalar spin chirality
of noncoplanar chiral spin textures. Most importantly, they come from the
lowest excitation, therefore they can be easily observed experimentally at low
temperatures due to the population effect. Similar to electronic Weyl nodes
close to the Fermi energy, Weyl magnon nodes in the lowest excitation are the
most important. Indeed, we show that the topological (anomalous) thermal Hall
effect in this system arises from nonvanishing Berry curvature due to Weyl
magnon nodes in the lowest excitation, and it depends on their distribution
(distance) in momentum space. The present result paves the way to directly
probe low excitation Weyl magnons and macroscopically broken time-reversal
symmetry in three-dimensional frustrated magnets with the anomalous thermal
Hall effect.Comment: 9 pages, 4 figures. Revised version. The first proposal of Weyl
magnons in this system can be found here arXiv:1708.04240. The present paper
proposes the first transport properties induced by Weyl magnons at the lowest
excitatio
As NMR of Ba(FeCo)As in High Magnetic Field
The superconducting state of an optimally doped single crystal of
Ba(FeCo)As was investigated by As NMR in high
magnetic fields from 6.4 T to 28 T. It was found that the Knight shift is least
affected by vortex supercurrents in high magnetic fields, T, revealing
slow, possibly higher order than linear, increase with temperature at , with . This is consistent with the
extended s-wave state with symmetry but the precise details of the gap
structure are harder to resolve. Measurements of the NMR spin-spin relaxation
time, , indicate a strong indirect exchange interaction at all
temperatures. Below the superconducting transition temperature vortex dynamics
lead to an anomalous dip in at the vortex freezing transition from which
we obtain the vortex phase diagram up to T.Comment: 13 pages, 9 figure
Human Milk Oligosaccharide Utilization in Intestinal Bifidobacteria Is Governed by Global Transcriptional Regulator NagR
Bifidobacterium longum subsp. infantis is a prevalent beneficial bacterium that colonizes the human neonatal gut and is uniquely adapted to efficiently use human milk oligosaccharides (HMOs) as a carbon and energy source. Multiple studies have focused on characterizing the elements of HMO utilization machinery in B. longum subsp. infantis; however, the regulatory mechanisms governing the expression of these catabolic pathways remain poorly understood. A bioinformatic regulon reconstruction approach used in this study implicated NagR, a transcription factor from the ROK family, as a negative global regulator of gene clusters encoding lacto-N-biose/galacto-N-biose (LNB/GNB), lacto-N-tetraose (LNT), and lacto-N-neotetraose (LNnT) utilization pathways in B. longum subsp. infantis. This conjecture was corroborated by transcriptome profiling upon nagR genetic inactivation and experimental assessment of binding of recombinant NagR to predicted DNA operators. The latter approach also implicated N-acetylglucosamine (GlcNAc), a universal intermediate of LNT and LNnT catabolism, and its phosphorylated derivatives as plausible NagR transcriptional effectors. Reconstruction of NagR regulons in various Bifidobacterium lineages revealed multiple potential regulon expansion events, suggesting evolution from a local regulator of GlcNAc catabolism in ancestral bifidobacteria to a global regulator controlling the utilization of mixtures of GlcNAc-containing host glycans in B. longum subsp. infantis and Bifidobacterium bifidum
Studies of B0-B0bar Mixing Properties with Inclusive Dilepton Events
We report a precise determination of the B0-B0bar mixing parameter Delta-m_d
based on the time evolution of same-sign and opposite-sign dilepton yields in
Upsilon(4S) decays. Data were collected with the Belle detector at KEKB. Using
data samples of 29.4 1/fb recorded at the Upsilon(4S) resonance and 3.0 1/fb
recorded at an energy 60MeV below the resonance, we measure Delta m_d = (0.503
+- 0.008(stat) +- 0.010(sys)) 1/ps. From the same analysis, we also measure the
ratio of charged and neutral B meson production at the Upsilon(4S), f+/f0 =
1.01 +- 0.03(stat) +- 0.09(sys), and CPT violation parameters in B0-B0bar
mixing, Re(cos theta) = 0.00 +- 0.12(stat) +- 0.01(sys) and Im(cos theta) =
0.03 +- 0.01(stat) +- 0.03(sys).Comment: Seven pages, two figures. Published in PR
As-75 NMR of Ba(Fe0.93Co0.07)(2)As-2 in high magnetic field
The superconducting state of an optimally doped single crystal of Ba(Fe0.93Co0.07)2As2 was investigated by 75As NMR in high magnetic fields from 6.4 to 28 T. It was found that the Knight shift is least affected by vortex supercurrents in high magnetic fields H\u3e11 T, revealing slow, possibly higher order than linear, increase with temperature at T≲0.5Tc, with Tc≈23 K. This is consistent with the extended s-wave state with A1g symmetry, but the precise details of the gap structure are harder to resolve. Measurements of the NMR spin-spin relaxation time T2 indicate a strong indirect exchange interaction at all temperatures. Below the superconducting transition temperature, abrupt changes in vortex dynamics lead to an anomalous dip in T2, consistent with vortex freezing from which we obtain the vortex phase diagram up to H=28 T
Neural protection by naturopathic compounds—an example of tetramethylpyrazine from retina to brain
Given the advantages of being stable in the ambient environment, being permeable to the blood–brain and/or blood–eye barriers and being convenient for administration, naturopathic compounds have growingly become promising therapeutic candidates for neural protection. Extracted from one of the most common Chinese herbal medicines, tetramethylpyrazine (TMP), also designated as ligustrazine, has been suggested to be neuroprotective in the central nervous system as well as the peripheral nerve network. Although the detailed molecular mechanisms of its efficacy for neural protection are understood limitedly, accumulating evidence suggests that antioxidative stress, antagonism for calcium, and suppression of pro-inflammatory factors contribute significantly to its neuroprotection. In animal studies, systemic administration of TMP (subcutaneous injection, 50 mg/kg) significantly blocked neuronal degeneration in hippocampus as well as the other vulnerable regions in brains of Sprague–Dawley rats following kainate-induced prolonged seizures. Results from us and others also demonstrated potent neuroprotective efficacy of TMP for retinal cells and robust benefits for brain in Alzheimer’s disease or other brain injury. These results suggest a promising prospect for TMP to be used as a treatment of specific neurodegenerative diseases. Given the assessment of the distribution, metabolism, excretion, and toxicity information that is already available on most neuroprotective naturopathic compounds such as TMP, it would not take much preclinical data to justify bringing such therapeutic compounds to clinical trials in humans
Local and Systemic Effects of Chronic Intracavernous Injection of Papaverine, Prostaglandine E1 and Saline in Primates
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