A first alignment of the LHCb Vertex Locator has been obtained from beam induced tracks at the LHC. A 450
GeV/
c protons were collided on a beam absorber during the LHC synchronisation tests of the ...anti-clockwise beam in August and September 2008. The resulting particle tracks have been reconstructed by the Vertex Locator. This was the first full reconstruction of tracks induced by the LHC beam. The quality of the data obtained is discussed. A total of 2200 tracks were reconstructed from the full data sample, and a first spatial alignment was obtained. The detector is aligned to an accuracy of
5
μ
m
in the sensor plane. The results confirm that all detector modules have not been displaced from their surveyed positions by more than
10
μ
m
.
First LHC beam induced tracks reconstructed in the LHCb VELO Parkes, C.; Borghi, S.; Bates, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2009, Letnik:
604, Številka:
1
Journal Article
Recenzirano
The Vertex Locator of the LHCb experiment has been used to fully reconstruct beam induced tracks at the LHC. A beam of protons was collided with a beam absorber during the LHC synchronisation test of ...the anti-clockwise beam on the weekend 22nd–24th August 2008. The resulting particles have been observed by the Vertex Locator. The LHCb Vertex Locator is a silicon micro-strip detector containing 21 planes of modules. Tracks were observed passing through up to 19 modules (38 silicon sensors). A total of over 700 tracks were reconstructed, and are being used to study the calibration and alignment of the detector.
A
bstract
The first observation of
Z
boson production in proton-lead collisions at a centre-of-mass energy per proton-nucleon pair of
s
N
N
= 5 TeV is presented. The data sample corresponds to an ...integrated luminosity of 1
.
6 nb
−1
collected with the LHCb detector. The
Z
candidates are reconstructed from pairs of oppositely charged muons with pseudorapidities between 2.0 and 4.5 and transverse momenta above 20 GeV
/
c. The invariant dimuon mass is restricted to the range 60 − 120 GeV
/
c. The
Z
production cross-section is measured to be
σ
Z
→
μ
+
μ
−
fwd
=
13.5
−
4.0
+
5.4
stat
.
±
1.2
syst
.
nb
in the direction of the proton beam and
σ
Z
→
μ
+
μ
−
bwd
=
10.7
−
5.1
+
8.4
stat
.
±
1.0
syst
.
nb
in the direction of the lead beam, where the first uncertainty is statistical and the second systematic.
Objective
To report the influence of maternal overweight and obesity on fetal growth and adiposity and effects of an antenatal dietary and lifestyle intervention among these women on measures of ...fetal growth and adiposity as secondary outcomes of the LIMIT Trial.
Design
Randomised controlled trial.
Setting
Public maternity hospitals in metropolitan Adelaide, South Australia.
Population
Pregnant women with a body mass index ≥ 25 kg/m2, and singleton gestation between 10+0 and 20+0 weeks.
Methods
Women were randomised to Lifestyle Advice or continued Standard Care and offered two research ultrasound scans at 28 and 36 weeks of gestation.
Main outcome measures
Ultrasound measures of fetal growth and adiposity.
Results
For each fetal body composition parameter, mean Z‐scores were substantially higher when compared with population standards. Fetuses of women receiving Lifestyle Advice demonstrated significantly greater mean mid‐thigh fat mass, when compared with fetuses of women receiving Standard Care (adjusted difference in means 0.17; 95% CI 0.02–0.32; P = 0.0245). While subscapular fat mass increased between 28 and 36 weeks of gestation in fetuses in both treatment groups, the rate of adipose tissue deposition slowed among fetuses of women receiving Lifestyle Advice, when compared with fetuses of women receiving Standard Care (P = 0.0160). No other significant differences were observed.
Conclusions
These findings provide the first evidence of changes to fetal growth following an antenatal dietary and lifestyle intervention among women who are overweight or obese.
Tweetable
Lifestyle advice for overweight and obese pregnant women modifies fetal body composition.
Tweetable
Lifestyle advice for overweight and obese pregnant women modifies fetal body composition.
A
bstract
A search for the doubly charmed baryon
$ \Xi_{cc}^{+} $
in the decay mode
$ \Xi_{cc}^{+}\to \Lambda_c^{+}{K^{-}}{\pi^{+}} $
is performed with a data sample, corresponding to an integrated ...luminosity of 0.65 fb
−1
, of
pp
collisions recorded at a centre-of-mass energy of 7 TeV. No significant signal is found in the mass range 3300-3800 MeV
/c
2
. Upper limits at the 95% confidence level on the ratio of the
$ \Xi_{cc}^{+} $
production cross-section times branching fraction to that of the
$ \Lambda_c^{+} $
,
R
, are given as a function of the
$ \Xi_{cc}^{+} $
mass and lifetime. The largest upper limits range from
R
< 1.5 × 10
−
2 for a lifetime of 100 fs to
R <
3
.
9 × 10
−4
for a lifetime of 400 fs.
Objective
To evaluate the effect of providing antenatal dietary and lifestyle advice on neonatal anthropometry, and to determine the inter‐observer variability in obtaining anthropometric ...measurements.
Design
Randomised controlled trial.
Setting
Public maternity hospitals across metropolitan Adelaide, South Australia.
Population
Pregnant women with a singleton gestation between 10+0 and 20+0 weeks, and body mass index (BMI) ≥25 kg/m2.
Methods
Women were randomised to either Lifestyle Advice (comprehensive dietary and lifestyle intervention over the course of pregnancy including dietary, exercise and behavioural strategies, delivered by a research dietician and research assistants) or continued Standard Care. Analyses were conducted using intention‐to‐treat principles.
Main outcome measures
Secondary outcome measures for the trial included assessment of infant body composition using body circumference and skinfold thickness measurements (SFTM), percentage body fat, and bio‐impedance analysis of fat‐free mass.
Results
Anthropometric measurements were obtained from 970 neonates (488 Lifestyle Advice Group, and 482 Standard Care Group). In 394 of these neonates (215 Lifestyle Advice Group, and 179 Standard Care Group) bio‐impedance analysis was also obtained. There were no statistically significant differences identified between those neonates born to women receiving Lifestyle Advice and those receiving Standard Care, in terms of body circumference measures, SFTM, percentage body fat, fat mass, or fat‐free mass. The intra‐class correlation coefficient for SFTM was moderate to excellent (0.55–0.88).
Conclusions
Among neonates born to women who are overweight or obese, anthropometric measures of body composition were not modified by an antenatal dietary and lifestyle intervention.
Tweetable
Lifestyle advice in pregnancy does not modify body composition of infants of overweight and obese women.
Tweetable
Lifestyle advice in pregnancy does not modify body composition of infants of overweight and obese women.
A
bstract
The production cross-sections of
B
mesons are measured in
pp
collisions at a centre-of-mass energy of 7 TeV, using data collected with the LHCb detector corresponding to a integrated ...luminosity of 0.36 fb
−1
. The
B
+
,
B
0
and
$ B_s^0 $
mesons are reconstructed in the exclusive decays
B
+
→
J
/
ψK
+
,
B
0
→
J
/
ψK
*0
and
$ B_s^0\to {J \left/ {{\psi \phi }} \right.} $
, with
J
/
ψ
→
μ
+
μ
−
,
K
*0
→
K
+
π
−
and
ϕ
→
K
+
K
−
. The differential cross-sections are measured as functions of
B
meson transverse momentum
p
T
and rapidity
y
, in the range 0
< p
T
<
40 GeV
/c
and 2
.
0
< y <
4
.
5. The integrated cross-sections in the same
p
T
and
y
ranges, including charge-conjugate states, are measured to be
$ \begin{array}{*{20}{c}} {\sigma \left( {pp\to {B^{+}}+X} \right)=38.9\pm 0.3\left( {\mathrm{stat}.} \right)\pm 2.5\left( {\mathrm{syst}.} \right)\pm 1.3\left( {\mathrm{norm}.} \right)\upmu \mathrm{b},} \hfill \\ {\sigma \left( {pp\to {B^0}+X} \right)=38.1\pm 0.6\left( {\mathrm{stat}.} \right)\pm 3.7\left( {\mathrm{syst}.} \right)\pm 4.7\left( {\mathrm{norm}.} \right)\upmu \mathrm{b},} \hfill \\ {\sigma \left( {pp\to B_s^0+X} \right)=10.5\pm 0.2\left( {\mathrm{stat}.} \right)\pm 0.8\left( {\mathrm{syst}.} \right)\pm 1.0\left( {\mathrm{norm}.} \right)\upmu \mathrm{b},} \hfill \\ \end{array} $
where the third uncertainty arises from the pre-existing branching fraction measurements.
A
bstract
Limits on the cross-section times branching fraction for neutral Higgs bosons, produced in
pp
collisions at
$ \sqrt{s}=7 $
TeV, and decaying to two tau leptons with pseudorapidities between ...2
.
0 and 4
.
5, are presented. The result is based on a dataset, corresponding to an integrated luminosity of 1
.
0 fb
−1
, collected with the LHCb detector. Candidates are identified by reconstructing final states with two muons, a muon and an electron, a muon and a hadron, or an electron and a hadron. A model independent upper limit at the 95% confidence level is set on a neutral Higgs boson cross-section times branching fraction. It varies from 8
.
6 pb for a Higgs boson mass of 90 GeV to 0
.
7 pb for a Higgs boson mass of 250 GeV, and is compared to the Standard Model expectation. An upper limit on tan
β
in the Minimal Supersymmetric Model is set in the
$ m_{{{h^0}}}^{\max } $
scenario. It ranges from 34 for a
CP
-odd Higgs boson mass of 90 GeV to 70 for a pseudo-scalar Higgs boson mass of 140 GeV.
A search is performed for heavy long-lived charged particles using 3.0 fb\(^{-1}\) of pp collisions collected at \(\sqrt{s}\)= 7 and 8 TeV with the LHCb detector. The search is mainly based on the ...response of the ring imaging Cherenkovdetectors to distinguish the heavy, slow-moving particles from muons. No evidence is found for the production of such long-lived states. The results are expressed as limits on the Drell-Yan production of pairs of long-lived particles, with both particles in the LHCb pseudorapidity acceptance, \(1.8 < \eta < 4.9\). The mass-dependent cross-section upper limits are in the range 2-4 fb (at 95\% CL) for masses between 124 and 309 GeV/c\(^2\).
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