84 research outputs found
Lp-PLA2 activity is associated with increased risk of diabetic retinopathy:a longitudinal disease progression study
Measurements of long-range near-side angular correlations in TeV proton-lead collisions in the forward region
Two-particle angular correlations are studied in proton-lead collisions at a
nucleon-nucleon centre-of-mass energy of TeV, collected
with the LHCb detector at the LHC. The analysis is based on data recorded in
two beam configurations, in which either the direction of the proton or that of
the lead ion is analysed. The correlations are measured in the laboratory
system as a function of relative pseudorapidity, , and relative
azimuthal angle, , for events in different classes of event
activity and for different bins of particle transverse momentum. In
high-activity events a long-range correlation on the near side, , is observed in the pseudorapidity range . This
measurement of long-range correlations on the near side in proton-lead
collisions extends previous observations into the forward region up to
. The correlation increases with growing event activity and is found
to be more pronounced in the direction of the lead beam. However, the
correlation in the direction of the lead and proton beams are found to be
compatible when comparing events with similar absolute activity in the
direction analysed.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-040.htm
Study of the production of and hadrons in collisions and first measurement of the branching fraction
The product of the () differential production
cross-section and the branching fraction of the decay () is
measured as a function of the beauty hadron transverse momentum, ,
and rapidity, . The kinematic region of the measurements is and . The measurements use a data sample
corresponding to an integrated luminosity of collected by the
LHCb detector in collisions at centre-of-mass energies in 2011 and in 2012. Based on previous LHCb
results of the fragmentation fraction ratio, , the
branching fraction of the decay is
measured to be \begin{equation*} \mathcal{B}(\Lambda_b^0\rightarrow J/\psi
pK^-)= (3.17\pm0.04\pm0.07\pm0.34^{+0.45}_{-0.28})\times10^{-4},
\end{equation*} where the first uncertainty is statistical, the second is
systematic, the third is due to the uncertainty on the branching fraction of
the decay , and the
fourth is due to the knowledge of . The sum of the
asymmetries in the production and decay between and
is also measured as a function of and .
The previously published branching fraction of , relative to that of , is updated.
The branching fractions of are determined.Comment: 29 pages, 19figures. All figures and tables, along with any
supplementary material and additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-032.htm
Evidence for the strangeness-changing weak decay
Using a collision data sample corresponding to an integrated luminosity
of 3.0~fb, collected by the LHCb detector, we present the first search
for the strangeness-changing weak decay . No
hadron decay of this type has been seen before. A signal for this decay,
corresponding to a significance of 3.2 standard deviations, is reported. The
relative rate is measured to be
, where and
are the and fragmentation
fractions, and is the branching
fraction. Assuming is bounded between 0.1 and
0.3, the branching fraction would lie
in the range from to .Comment: 7 pages, 2 figures, All figures and tables, along with any
supplementary material and additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-047.htm
Search for the rare decays and
A search for the rare decay of a or meson into the final
state is performed, using data collected by the LHCb experiment
in collisions at and TeV, corresponding to an integrated
luminosity of 3 fb. The observed number of signal candidates is
consistent with a background-only hypothesis. Branching fraction values larger
than for the decay mode are
excluded at 90% confidence level. For the decay
mode, branching fraction values larger than are excluded at
90% confidence level, this is the first branching fraction limit for this
decay.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-044.htm
Synaptic and transcriptionally downregulated genes are associated with cortical thickness differences in autism.
Differences in cortical morphology-in particular, cortical volume, thickness and surface area-have been reported in individuals with autism. However, it is unclear what aspects of genetic and transcriptomic variation are associated with these differences. Here we investigate the genetic correlates of global cortical thickness differences (ÎCT) in children with autism. We used Partial Least Squares Regression (PLSR) on structural MRI data from 548 children (166 with autism, 295 neurotypical children and 87 children with ADHD) and cortical gene expression data from the Allen Institute for Brain Science to identify genetic correlates of ÎCT in autism. We identify that these genes are enriched for synaptic transmission pathways and explain significant variation in ÎCT. These genes are also significantly enriched for genes dysregulated in the autism post-mortem cortex (Odd Ratio (OR)â=â1.11, Pcorrectedââ10-14), driven entirely by downregulated genes (ORâ=â1.87, Pcorrectedââ10-15). We validated the enrichment for downregulated genes in two independent data sets: Validation 1 (ORâ=â1.44, Pcorrectedâ=â0.004) and Validation 2 (ORâ=â1.30; Pcorrectedâ=â0.001). We conclude that transcriptionally downregulated genes implicated in autism are robustly associated with global changes in cortical thickness variability in children with autism
Study of Ï(2S) production and cold nuclear matter effects in pPb collisions at â sNN = 5 TeV
The production of Ï(2S) mesons is studied in dimuon final states using proton-lead (pPb) collision data collected by the LHCb detector. The data sample corresponds to an integrated luminosity of 1.6 nbâ1. The nucleon-nucleon centre-of-mass energy of the pPb collisions is (Formula presented.) TeV. The measurement is performed using Ï(2S) mesons with transverse momentum less than 14 GeV/c and rapidity y in the ranges 1.5 < y < 4.0 and â5.0 < y < â2.5 in the nucleon-nucleon centre-of-mass system. The forward-backward production ratio and the nuclear modification factor are determined for Ï(2S) mesons. Using the production cross-section results of Ï(2S) and J/Ï mesons from b-hadron decays, the (Formula presented.) cross-section in pPb collisions at (Formula presented.) TeV is obtained
Measurements of long-range near-side angular correlations in âsNN = 5 TeV proton-lead collisions in the forward region
Two-particle angular correlations are studied in proton-lead collisions at a nucleonânucleon centre-of-mass energy of âsNN = 5 TeV , collected with the LHCb detector at the LHC. The analysis is based on data recorded in two beam configurations, in which either the direction of the proton or that of the lead ion is analysed. The correlations are measured in the laboratory system as a function of relative pseudorapidity, Îη, and relative azimuthal angle, ÎÏ, for events in different classes of event activity and for different bins of particle transverse momentum. In high-activity events a long-range correlation on the near side, Î Ï â 0 , is observed in the pseudorapidity range 2.0 < η < 4.9 . This measurement of long-range correlations on the near side in proton-lead collisions extends previous observations into the forward region up to η = 4.9 . The correlation increases with growing event activity and is found to be more pronounced in the direction of the lead beam. However, the correlation in the direction of the lead and proton beams are found to be compatible when comparing events with similar absolute activity in the direction analysed
Search for the doubly heavy baryon decaying to
A first search for the
decay is performed by the LHCb experiment with a data sample of proton-proton
collisions, corresponding to an integrated luminosity of
recorded at centre-of-mass energies of 7, 8, and . Two peaking structures are seen with a local (global) significance of
and standard deviations at masses of
and , respectively. Upper limits are set on the baryon
production cross-section times the branching fraction relative to that of the
decay at centre-of-mass energies of 8 and
, in the and in the
rapidity and transverse-momentum ranges from 2.0 to 4.5 and 0 to
, respectively. Upper limits are presented
as a function of the mass and lifetime.Comment: All figures and tables, along with machine-readable versions and any
supplementary material and additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-005.html (LHCb
public pages
First observation of a doubly charged tetraquark and its neutral partner
A combined amplitude analysis is performed for the decays and , which are
related by isospin symmetry. The analysis is based on data collected by the
LHCb detector in proton-proton collisions at center-of-mass energies of 7, 8
and 13. The full data sample corresponds to an integrated
luminosity of 9. Two new resonant states with masses of
and widths of
are observed, which decay to and
respectively. The former state indicates the first observation of
a doubly charged open-charm tetraquark state with minimal quark content
, and the latter state is a neutral tetraquark composed of
quarks. Both states are found to have spin-parity ,
and their resonant parameters are consistent with each other, which suggests
that they belong to an isospin triplet.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-026.html (LHCb
public pages
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