344 research outputs found
A Novel Composite Material Designed from FeSi Powder and Mn 0.8
A design of the novel microcomposite material composed of spherical FeSi particles and Mn0.8Zn0.2Fe2O4 ferrite is reported together with a characterization of basic mechanical and electrical properties. The sol-gel autocombustion method was used for a preparation of Mn0.8Zn0.2Fe2O4 ferrite, which has a spinel-type crystal structure as verified by XRD and TEM analysis. The final microcomposite samples were prepared by a combination of the traditional PM compaction technique supplemented with unconventional microwave sintering process of the prepared green compacts. The composition and distribution of the secondary phase formed by the spinel ferrite were examined by SEM. It is demonstrated that the prepared composite material has a tight arrangement without any significant porosity, which manifests itself through superior mechanical properties (high mechanical hardness, Young modulus, and transverse rupture strength) and specific electric resistivity compared to the related composite materials including resin as the organic binder
Model-independent search for CP violation in D0âKâK+ÏâÏ+ and D0âÏâÏ+Ï+Ïâ decays
A search for CP violation in the phase-space structures of D0 and View the MathML source decays to the final states KâK+ÏâÏ+ and ÏâÏ+Ï+Ïâ is presented. The search is carried out with a data set corresponding to an integrated luminosity of 1.0 fbâ1 collected in 2011 by the LHCb experiment in pp collisions at a centre-of-mass energy of 7 TeV. For the KâK+ÏâÏ+ final state, the four-body phase space is divided into 32 bins, each bin with approximately 1800 decays. The p-value under the hypothesis of no CP violation is 9.1%, and in no bin is a CP asymmetry greater than 6.5% observed. The phase space of the ÏâÏ+Ï+Ïâ final state is partitioned into 128 bins, each bin with approximately 2500 decays. The p-value under the hypothesis of no CP violation is 41%, and in no bin is a CP asymmetry greater than 5.5% observed. All results are consistent with the hypothesis of no CP violation at the current sensitivity
Search for the lepton-flavor-violating decays Bs0âe±Όâ and B0âe±Όâ
A search for the lepton-flavor-violating decays Bs0âe±Όâ and B0âe±Όâ is performed with a data sample, corresponding to an integrated luminosity of 1.0ââfb-1 of pp collisions at âs=7ââTeV, collected by the LHCb experiment. The observed number of Bs0âe±Όâ and B0âe±Όâ candidates is consistent with background expectations. Upper limits on the branching fractions of both decays are determined to be B(Bs0âe±Όâ)101ââTeV/c2 and MLQ(B0âe±Όâ)>126ââTeV/c2 at 95% C.L., and are a factor of 2 higher than the previous bounds
Observation of the decay
The decay is observed for the first
time, using proton-proton collisions collected with the LHCb detector
corresponding to an integrated luminosity of 3fb. A signal yield of
decays is reported with a significance of 6.2 standard deviations.
The ratio of the branching fraction of \B_c \rightarrow J/\psi K^+ K^- \pi^+
decays to that of decays is measured to be
, where the first uncertainty is statistical and the
second is systematic.Comment: 18 pages, 2 figure
Observation of associated production of a boson with a meson in the~forward region
A search for associated production of a boson with an open charm meson is
presented using a data sample, corresponding to an integrated luminosity of
of proton--proton collisions at a centre-of-mass energy
of 7\,TeV, collected by the LHCb experiment. %% Seven candidate events for
associated production of a boson with a meson and four candidate
events for a boson with a meson are observed with a combined
significance of 5.1standard deviations. The production cross-sections in the
forward region are measured to be where the first uncertainty is statistical and the
second systematic.Comment: 18 pages, 2 figure
Measurements of the , , meson and baryon lifetimes
Measurements of -hadron lifetimes are reported using collision data,
corresponding to an integrated luminosity of 1.0fb, collected by the
LHCb detector at a centre-of-mass energy of Tev. Using the exclusive decays
, , ,
and the average decay
times in these modes are measured to be = 0.004 0.003 ps, =
0.006 0.004 ps, = 0.013
0.005 ps, = 0.027
0.006 ps and = 0.011
0.005 ps, where the first uncertainty is statistical and the second is
systematic. These represent the most precise lifetime measurements in these
decay modes. In addition, ratios of these lifetimes, and the ratio of the
decay-width difference, , to the average width, , in
the system, , are
reported. All quantities are found to be consistent with Standard Model
expectations.Comment: 28 pages, 4 figures. Updated reference
Observation of the decay B+câBÂșsÏ+
The result of a search for the decay B+câBÂșsÏ+ is presented, using the BÂșsâDs-Ï+ and BÂșsâJ/ÏÏ channels. The analysis is based on a data sample of pp collisions collected with the LHCb detector, corresponding to an integrated luminosity of 1ââfb-1 taken at a center-of-mass energy of 7 TeV, and 2ââfb-1 taken at 8 TeV. The decay B+câBÂșsÏ+ is observed with significance in excess of 5 standard deviations independently in both decay channels. The measured product of the ratio of cross sections and branching fraction is [Ï(Bc+)/Ï(BÂșs)]ĂB(Bc+âBÂșsÏ+)=[2.37±0.31â(stat)±0.11â(syst)-0.13+0.17(ÏBc+)]Ă10-3, in the pseudorapidity range 2<η(B)<5, where the first uncertainty is statistical, the second is systematic, and the third is due to the uncertainty on the Bc+ lifetime. This is the first observation of a B meson decaying to another B meson via the weak interaction
Study of B0(s)âK0Sh+hâČâ decays with first observation of B0sâK0SK±Ïâ and B0sâK0SÏ+Ïâ
A search for charmless three-body decays of B 0 and B0s mesons with a K0S meson in the final state is performed using the pp collision data, corresponding to an integrated luminosity of 1.0 fbâ1, collected at a centre-of-mass energy of 7 TeV recorded by the LHCb experiment. Branching fractions of the B0(s)âK0Sh+hâČâ decay modes (h (âČ) = Ï, K), relative to the well measured B0âK0SÏ+Ïâ decay, are obtained. First observation of the decay modes B0sâK0SK±Ïâ and B0sâK0SÏ+Ïâ and confirmation of the decay B0âK0SK±Ïâ are reported. The following relative branching fraction measurements or limits are obtained B(B0âK0SK±Ïâ)B(B0âK0SÏ+Ïâ)=0.128±0.017(stat.)±0.009(syst.), B(B0âK0SK+Kâ)B(B0âK0SÏ+Ïâ)=0.385±0.031(stat.)±0.023(syst.), B(B0sâK0SÏ+Ïâ)B(B0âK0SÏ+Ïâ)=0.29±0.06(stat.)±0.03(syst.)±0.02(fs/fd), B(B0sâK0SK±Ïâ)B(B0âK0SÏ+Ïâ)=1.48±0.12(stat.)±0.08(syst.)±0.12(fs/fd)B(B0sâK0SK+Kâ)B(B0âK0SÏ+Ïâ)â[0.004;0.068]at90%CL
Observations of BÂșsâÏ(2S)η and BÂș(s)âÏ(2S)Ï+Ï- decays
First observations of the B0s
âÏ(2S)η, B0 âÏ(2S)Ï
+
Ï
â and B0s
âÏ(2S)Ï
+
Ï
â decays are made
using a dataset corresponding to an integrated luminosity of 1.0 fbâ1 collected by the LHCb experiment in
protonâproton collisions at a centre-of-mass energy of
â
s = 7 TeV. The ratios of the branching fractions
of each of the Ï(2S) modes with respect to the corresponding J/Ï decays are
B(B0s
âÏ(2S)η)
Ă·
B(B0s
âJ/Ïη)
= 0.83± 0.14 (stat)±0.12 (syst) ±0.02 (B),
;
B(B0âÏ(2S)Ï
+
Ï
â
)
Ă·
B(B0âJ/ÏÏ
+
Ï
â
)
= 0.56± 0.07 (stat)±0.05 (syst)± 0.01 (B),
;
B(B0s
âÏ(2S)Ï
+
Ï
â
)
Ă·
B(B0s
âJ/ÏÏ
+
Ï
â
)
= 0.34± 0.04 (stat)±0.03 (syst)± 0.01 (B),
where the third uncertainty corresponds to the uncertainties of the dilepton branching fractions of the J/Ï
and Ï(2S) meson decays
Measurement of charged particle multiplicities and densities in pp collisions root s=7 TeV in the forward region
Charged particle multiplicities are studied in proton-proton collisions in the forward region at a centre-of-mass energy of TeV with data collected by the LHCb detector. The forward spectrometer allows access to a kinematic range of in pseudorapidity, momenta greater than and transverse momenta greater than . The measurements are performed using events with at least one charged particle in the kinematic acceptance. The results are presented as functions of pseudorapidity and transverse momentum and are compared to predictions from several Monte Carlo event generators
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