214 research outputs found
Lattice Matrix Elements and CP Violation in B and K Physics: Status and Outlook
Status of lattice calculations of hadron matrix elements along with CP
violation in B and in K systems is reviewed. Lattice has provided useful input
which, in conjunction with experimenatl data, leads to the conclusion that
CP-odd phase in the CKM matrix plays the dominant role in the observed
asymmetry in . It is now quite likely that any beyond the SM,
CP-odd, phase will cause only small deviations in B-physics. Search for the
effects of the new phase(s) will consequently require very large data samples
as well as very precise theoretical predictions. Clean determination of {\it
all} the angles of the unitarity triangle therefore becomes essential. In this
regard processes play a unique role. Regarding K-decays,
remarkable progress made by theory with regard to maintenance of chiral
symmetry on the lattice is briefly discussed. First application already provide
quantitaive information on and the rule. The enhancement
in appears to arise solely from tree operators, esp. ; penguin
contribution to appears to be very small. However, improved
calculations are necessary for \epsilon^'/epsilon as there the contributions
of QCD penguins and electroweak penguins largely seem to cancel. There are good
reasons, though, to believe that these cancellations will not survive
improvements that are now underway. Importance of determining the unitarity
triangle purely from K-decays is also emphasized.Comment: Invited talk at the 9th International Symposium on Particles, Strings
and Cosmology (PASCOS 03), Mumbai (Bombay) India,3-8 Jan 200
Pion photoproduction on the nucleon in the quark model
We present a detailed quark-model study of pion photoproduction within the
effective Lagrangian approach. Cross sections and single-polarization
observables are investigated for the four charge channels, , , , and .
Leaving the coupling strength to be a free parameter, we obtain a
reasonably consistent description of these four channels from threshold to the
first resonance region. Within this effective Lagrangian approach, strongly
constrainted by the quark model, we consider the issue of double-counting which
may occur if additional {\it t}-channel contributions are included.Comment: Revtex, 35 pages, 16 eps figures; version to appear on PR
Photoproduction of pions and properties of baryon resonances from a Bonn-Gatchina partial wave analysis
Masses, widths and photocouplings of baryon resonances are determined in a
coupled-channel partial wave analysis of a large variety of data. The
Bonn-Gatchina partial wave formalism is extended to include a decomposition of
t- and u-exchange amplitudes into individual partial waves. The multipole
transition amplitudes for and are
given and compared to results from other analyses.Comment: 18 pages, 14 figure
Measurement of the ratio of branching fractions BR(B0 -> K*0 gamma)/BR(Bs0 -> phi gamma)
The ratio of branching fractions of the radiative B decays B0 -> K*0 gamma
and Bs0 -> phi gamma has been measured using 0.37 fb-1 of pp collisions at a
centre of mass energy of sqrt(s) = 7 TeV, collected by the LHCb experiment. The
value obtained is BR(B0 -> K*0 gamma)/BR(Bs0 -> phi gamma) = 1.12 +/- 0.08
^{+0.06}_{-0.04} ^{+0.09}_{-0.08}, where the first uncertainty is statistical,
the second systematic and the third is associated to the ratio of fragmentation
fractions fs/fd. Using the world average for BR(B0 -> K*0 gamma) = (4.33 +/-
0.15) x 10^{-5}, the branching fraction BR(Bs0 -> phi gamma) is measured to be
(3.9 +/- 0.5) x 10^{-5}, which is the most precise measurement to date.Comment: 15 pages, 1 figure, 2 table
P-wave excited baryons from pion- and photo-induced hyperon production
We report evidence for , , ,
, , and , and find
indications that might have a companion state at 1970\,MeV. The
controversial is not seen. The evidence is derived from a
study of data on pion- and photo-induced hyperon production, but other data are
included as well. Most of the resonances reported here were found in the
Karlsruhe-Helsinki (KH84) and the Carnegie-Mellon (CM) analyses but were
challenged recently by the Data Analysis Center at GWU. Our analysis is
constrained by the energy independent scattering amplitudes from either
KH84 or GWU. The two amplitudes from KH84 or GWU, respectively, lead to
slightly different branching ratios of contributing resonances but the
debated resonances are required in both series of fits.Comment: 22 pages, 28 figures. Some additional sets of data are adde
Agricultura orgĂąnica em ĂĄreas urbanas e periurbanas com base na agroecologia.
A agricultura orgĂąnica com base na agroecologia Ă© o mote tecnolĂłgico adequado Ă realidade dos agroecossistemas urbanos. Este artigo ressalta a necessidade de se desenvolver tecnologias e insumos especĂficos. A partir de experiĂȘncias com agricultura urbana em diferentes paĂses em desenvolvimento, evidencia-se a necessidade de se buscar capacidades locais e apoio do poder pĂșblico, especialmente nas iniciativas da sociedade organizada e mobilizada para a produção agrĂcola urbana
Production, Commissioning and First Data of the LHCb Silicon Tracker
We give here a short review of the LHCb Silicon Tracker, the main points of the module production and quality control, followed by the commissioning of the detector. Problems that were found during production or commissioning are described and the first performance assessment of the installed detector with âbeam dataâ is given
Understanding Streptococcus suis serotype 2 infection in pigs through a transcriptional approach
<p>Abstract</p> <p>Background</p> <p><it>Streptococcus suis </it>serotype 2 (<it>S. suis </it>2) is an important pathogen of pigs. <it>S suis 2 </it>infections have high mortality rates and are characterized by meningitis, septicemia and pneumonia. <it>S. suis </it>2 is also an emerging zoonotic agent and can infect humans that are exposed to pigs or their by-products. To increase our knowledge of the pathogenesis of meningitis, septicemia and pneumonia in pigs caused by <it>S. suis </it>2, we profiled the response of peripheral blood mononuclear cells <b>(</b>PBMC), brain and lung tissues to infection with <it>S. suis </it>2 strain SC19 using the Affymetrix Porcine Genome Array.</p> <p>Results</p> <p>A total of 3,002 differentially expressed transcripts were identified in the three tissues, including 417 unique genes in brain, 210 in lung and 213 in PBMC. These genes showed differential expression (DE) patterns on analysis by visualization and integrated discovery (DAVID). The DE genes involved in the immune response included genes related to the inflammatory response (CD163), the innate immune response (TLR2, TLR4, MYD88, TIRAP), cell adhesion (CD34, SELE, SELL, SELP, ICAM-1, ICAM-2, VCAM-1), antigen processing and presentation (MHC protein complex) and angiogenesis (VEGF), together with genes encoding cytokines (interleukins). Five selected genes were validated by qRT-PCR analysis.</p> <p>Conclusions</p> <p>We studied the response to infection with <it>S. suis </it>2 strain SC19 by microarray analysis. Our findings confirmed some genes identified in previous studies and discovered numerous additional genes that potentially function in <it>S. suis </it>2 infections in vivo. This new information will form the foundation of future investigations into the pathogenesis of <it>S. suis</it>.</p
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