25 research outputs found
Measurement of the top quark mass using the matrix element technique in dilepton final states
We present a measurement of the top quark mass in ppÂŻ collisions at a center-of-mass energy of 1.96 TeV at the Fermilab Tevatron collider. The data were collected by the D0 experiment corresponding to an integrated luminosity of 9.7ââfbâ1. The matrix element technique is applied to ttÂŻ events in the final state containing leptons (electrons or muons) with high transverse momenta and at least two jets. The calibration of the jet energy scale determined in the lepton+jets final state of ttÂŻ decays is applied to jet energies. This correction provides a substantial reduction in systematic uncertainties. We obtain a top quark mass of mt=173.93±1.84ââGeV
Studies of X(3872) and Ï(2S) production in p\bar{p}over-bar collisions at 1.96 TeV
We present various properties of the production of the X (3872) and Ï(2S) states based on 10.4fbâŸÂč collected by the D0 experiment in Tevatron p\bar{p} collisions at \sqrt{s} = 1.96 TeV. For both states, we measure the nonprompt fraction fNP of the inclusive production rate due to decays of b-flavored hadrons. We find the fNP values systematically below those obtained at the LHC. The fNP fraction for Ï(2S) increases with transverse momentum, whereas for the X(3872) it is constant within large uncertainties, in agreement with the LHC results. The ratio of prompt to nonprompt Ï(2S) production, (1 - fNP)/fNP, decreases only slightly going from the Tevatron to the LHC, but for the X(3872), this ratio decreases by a factor of about 3. We test the soft-pion signature of the X(3872) modeled as a weakly bound charm-meson pair by studying the production of the X(3872) as a function of the kinetic energy of the X(3872) and the pion in the X(3872) Ï center-of-mass frame. For a subsample consistent with prompt production, the results are incompatible with a strong enhancement in the production of the X(3872) at the small kinetic energy of the X(3872) and the Ï in the X(3872)Ï center-of-mass frame expected for the X + soft-pion production mechanism. For events consistent with being due to decays of hadrons, there is no significant evidence for the soft-pion effect, but its presence at the level expected for the binding energy of 0.17 MeV and the momentum scale Î = M(Ï) is not ruled out
Properties of Z±c(3900) produced in pp¯ collisions
We study the production of the exotic charged charmoniumlike state
Z
±
c
(
3900
)
in
p
ÂŻ
p
collisions through the sequential process
Ï
(
4260
)
â
Z
±
c
(
3900
)
Ï
â
,
Z
±
c
(
3900
)
â
J
/
Ï
Ï
±
. Using the subsample of candidates originating from semi-inclusive weak decays of
b
-flavored hadrons, we measure the invariant mass and natural width to be
M
=
3902.6
+
5.2
â
5.0
(
stat
)
+
3.3
â
1.4
(
syst
)
â
â
MeV
and
Î
=
3
2
+
28
â
21
(
stat
)
+
26
â
7
(
syst
)
â
â
MeV
, respectively. We search for prompt production of the
Z
±
c
(
3900
)
through the same sequential process. No significant signal is observed, and we set an upper limit of 0.70 at the 95% credibility level on the ratio of prompt production to the production via
b
-hadron decays. The study is based on
10.4
â
â
f
b
â
1
of
p
ÂŻ
p
collision data collected by the D0 experiment at the Fermilab Tevatron collider
Combination of D0 measurements of the top quark mass
We present a combination of measurements of the top quark mass by the D0 experiment in the lepton+jets and dilepton channels. We use all the data collected in Run I (1992â1996) at âs=1.8ââTeV and Run II (2001â2011) at âs=1.96ââTeV of the Tevatron pÂŻp collider, corresponding to integrated luminosities of 0.1ââfbâ1 and 9.7ââfbâ1, respectively. The combined result is: mt=174.95±0.40(stat)±0.64(syst)ââGeV=174.95±0.75ââGeV
Treatment with l-citrulline and metformin in Duchenne muscular dystrophy: study protocol for a single-centre, randomised, placebo-controlled trial
Improved Muscle Function in Duchenne Muscular Dystrophy through L-Arginine and Metformin: An Investigator-Initiated, Open-Label, Single-Center, Proof-Of-Concept-Study
Poly(vinyl trimethylsilane) and block copolymers of vinyltrimethylsilane with isoprene: anionic polymerization,morphology and gas transport properties.
A new methodology is proposed to estimate 3D displacement fields from pairs
of images obtained from X-Ray Computed Micro Tomography (XCMT). Contrary to
local approaches, a global approach is followed herein that evaluates {\em
continuous} displacement fields. Although any displacement basis could be
considered, the procedure is specialized to finite element shape functions. The
method is illustrated with the analysis of a compression test on a
polypropylene solid foam (independently studied in a companion paper). A good
stability of the measured displacement field is obtained for cubic element
sizes ranging from 16 voxels to 6 voxels.Comment: nombre de pages = 3