Among the observed variety of the natural phenomena reflected in experimental results, there are just a few physical features offering a view of a given fragment of the mosaic of physical laws in its ...entirety. One such remarkable fundamental feature is R, the ratio of the inclusive cross section of electron-positron annihilation into hadrons to the cross section of muon pair production in the Born approximation. We discuss experiments on measuring the R(s) ratio in the energy range 1.84-3.72 GeV.
The Super Charm-Tau Factory is an electron-positron collider project in Novosibirsk with a peak luminosity of 1035cm−1s−1 operating in the center of mass energy range between 2 and 6 GeV. The physics ...program of the experiment in general is devoted to the study of charm quark and tau lepton. Conceptual designs of the collider and a universal detector are presented. The dedicated particle identification (PID) system is required to provide the state-of-the-art level of μ/π separation for the particle momenta up to 1.2GeV/c. The following options for the PID system are considered in this paper: Focusing Aerogel RICH (FARICH) detector composed of 4-layer aerogel tiles, threshold Cherenkov counters based on aerogel and shifter (ASHIPH), Focusing DIRC (FDIRC) counter and time-of-flight (ToF) detector combined with the time-of-propagation (ToP) approach providing a time resolution better than 30ps. Also the capabilities of particles separation in tracking system are discussed. Comparison of PID approaches with help of parametric simulation is performed.
A
bstract
We present the study of the decay
J/ψ
→
ρπ
. The results are based on of 5.2 million
J/ψ
events collected by the KEDR detector at the VEPP-4M collider. The branching fractions are measured ...to be
B
(
J/ψ
→
ρπ
) = (2
.
072 ± 0
.
017 ± 0
.
062) ∙ 10
−
2
and
B
(
J/ψ
→
π
+
π
−
π
0
) = (1
.
878 ± 0
.
013 ± 0
.
051) ∙ 10
−
2
, where the first uncertainties are statistical and the second systematic. Our results are more precise than the previous relative measurements.
A review is presented of experiments performed using the KEDR detector at the VEPP-4M accelerator complex for the precise measurement of particle masses. The resonant depolarization method, proposed ...in 1975 at the G I Budker Institute of Nuclear Physics of the RAS Siberian Branch for measuring beam energy, has undergone further development in the experiments described; an unprecedented accuracy of has been achieved. Application of this method together with measurement of the Compton backscattering energy allowed a series of experiments to be carried out which have provided the world's most accurate mass values for the , and mesons and for the -lepton.
The available data on the DD‾ and inclusive hadronic cross sections in the ψ(3770) region from the BaBar, Belle, BES-II, CLEO and KEDR experiments have been analyzed assuming that systematic ...uncertainties on cross sections measured by various detectors are not correlated. Four theoretical models predicting the ψ(3770) line shape were considered for the DD‾ channel. All of them gave satisfactory description of the data. The combined analysis of the DD‾ and inclusive hadronic channels was performed using the model based on the vector dominance approach and accounting for the contribution of the ψ(2S) tail to the DD‾ cross section. The following values of the mass, total width, electron width and decay probability to the non-DD‾ states were obtained:M (MeV)Γ (MeV)Γee (eV)BnDD‾3779.8±0.625.8±1.3196±180.164±0.049 where the errors quoted include both statistical and dominant systematic uncertainties.
Budker Institute of Nuclear Physics is actively evolving the Super Charm-Tau Factory project. A drift chamber with a small hexagonal cell was proposed for this collider. For experimental measurements ...of a spatial resolution, a drift chamber small prototype consisting of seven cells has been developed. The experiments have been carried out in He/C3H8 (60/40) and He/C2H6 (50/50) gas mixtures at different gas gains using cosmic particles. For this purpose, a calibration procedure for R(t, α) has been developed and fine-tuned, taking into account small prototype features and an angular dependence of isochrones at the edge of the cells. As a result, the average spatial resolutions are less than 100μm for gas gains greater than 5⋅104.
Based on the full BABAR data sample, we report improved measurements of the ratios R(D(*))=B(B̄→D(*)τ⁻ν¯τ)/B(B̄→D(*)ll¯ν¯l), where l is either e or μ. These ratios are sensitive to new physics ...contributions in the form of a charged Higgs boson. We measure R(D)=0.440±0.058±0.042 and R(D*)=0.332±0.024±0.018, which exceed the standard model expectations by 2.0σ and 2.7σ, respectively. Taken together, our results disagree with these expectations at the 3.4σ level. This excess cannot be explained by a charged Higgs boson in the type II two-Higgs-doublet model.
New drift chamber for the KEDR detector Basok, I Yu; Blinov, V E; Bykov, A V ...
Journal of instrumentation,
10/2014, Letnik:
9, Številka:
10
Journal Article
Recenzirano
For further implementation of physical research program at the KEDR detector and for accompanying equipment upgrade the new drift chamber is currently being developed. This main tracking and ...momentum-measuring system represents gas multilayer wire chamber operating in proportional mode. Design features and modifications versus existing chamber are described. Using prototype the spatial resolution in various gas mixtures is being studied. Preliminary results of spatial resolution measurements are presented.
We study the process e + e − → e + e − η ′ in the double-tag mode and measure for the first time the γ * γ * → η ′ transition form factor F η′ ( Q 2 1 , Q 2 2 ) in the momentum-transfer range 2 < Q 2 ...1 , Q 2 2 < 60 GeV 2 . The analysis is based on a data sample corresponding to an integrated luminosity of around 469 fb − 1 collected at the PEP-II e + e − collider with the BABAR detector at center-of-mass energies near 10.6 GeV.
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