122162108
Precision timing with liquid ionization calorimeters
We present timing measurements performed with a liquid krypton electromagnetic accordion calorimeter, measured in an electron beam over an energy range of 5–20 GeV. A novel discriminator with an amplitude-independent timing response was used to extract the inherently accurate timing information from the calorimeter. As expected, the timing resolution στ is observed to vary inversely with the signal amplitude, which is proportional to the deposited energy E. We measure a resolution of στ = 4.15±0.06 GeV ns/E for a sum of 5×5 towers with dimensions 2.7×2.5 cm2 each. From this we deduce that the timing resolution for an individual tower is approximately 0.8 GeV ns/E.
206324074
Determination of the branching ratio of the decay pi 0-->e+e-
Employing the decay chain K + →π + p 0 , π 0 →e + e - we have observed the decay π 0 →e + e - . With a signal sample of ≃21 events we measure the branching ratio for π 0 →e + e - to be (6.9±2.3±0.6)×10 -8 , normalized to the decay K + →π + p 0 , π 0 →e + e - γ. This result is consistent with the unitarity lower bound and the published 90% confidence level upper limit of 13×10 -8
209835401
Search for events with large missing transverse momentum, jets, and at least two tau leptons in 7 TeV proton–proton collision data with the ATLAS detector
A search for events with large missing transverse momentum, jets, and at least two tau leptons has been performed using 2 fb(-1) of proton-proton collision data at root s = 7 TeV recorded with the ...
55159826
Full supersymmetry simulation for ATLAS in DC1
This note reports results from a simulation of 100k events for one example of a minimal SUGRA supersymmetry case at the LHC using full simulation of the ATLAS detector. It was carried out as part ATLAS Data Challenge 1.
121553628
Calibration of the Yangbajing Air-shower Core detector using the test beam of BEPCII
Yangbajing Air shower Core detector(YAC) has been developed for the next phase of Tibet air-shower experiment to measure the chemical composition of cosmic rays in “knee” region. A preparation is made for calibration of the linearity of the dynamic range and position dependence of light yield of YAC using test beam of BEPCII. A scraper will be used to attenuate the electron beam intensity from about 10 10 /pulse to 10 2 –10 6 /pulse. A Faraday cup, a thick ionization chamber and a thin ionization chamber are being manufactured to monitor the beam intensity covering dynamic range from 10 2 /pulse to 10 10 /pulse.
197518332
Performance of missing transverse momentum reconstructionin proton-proton collisions at √s = 7 TeV with ATLAS
The measurement of missing transverse momentum in the ATLAS detector, described in this paper, makes use of the full event reconstruction and a calibration based on reconstructed physics objects. The performance of the missing transverse momentum reconstruction is evaluated using data collected in pp collisions at a centre-of-mass energy of 7 TeV in 2010. Minimum bias events and events with jets of hadrons are used from data samples corresponding to an integrated luminosity of about 0.3 nb^(−1) and 600 nb^(−1) respectively, together with events containing a Z boson decaying to two leptons (electrons or muons) or a W boson decaying to a lepton (electron or muon) and a neutrino, from a data sample corresponding to an integrated luminosity of about 36 pb^(−1). An estimate of the systematic uncertainty on the missing transverse momentum scale is presented.
18706766
Recent Results on $\psi$ (3770) Physics at BES-II
About 33, 6.5 and 1.0 pb$^{-1}$ of $e^+e^-$ annihilation data were, respectively, taken around the center-of-mass energies of $\sqrt s=$ 3.773 GeV, at $\sqrt s=$ 3.650 GeV and at $\sqrt s=$ 3.6648 GeV with the BES-II detector at the BEPC collider. By analyzing these data sets, we measure the branching fraction for $\psi(3770)\to$ non-$D\bar D$; observe an anomalous line shape of the cross section for $e^+e^-\to$ hadrons in the energy region from 3.650 to 3.872 GeV; and measure the line shapes of the $D^+D^-$, $D^0\bar D^0$ and $D\bar D$ production and the ratios of the production rates of $D^+D^-$ and $D^0\bar D^0$ in $e^+e^-$ annihilation at $\psi(3770)$ resonance. We also search for $\psi(3770)$ decay into exclusive light hadron processes containing $K^0_S$ or $\pi^0\pi^0$ mesons in the final states.
125302092
Measurements of the line shapes of D anti-D production and the ratio of the production rates of D+ D- and D0 anti-D0 in e+ e- annihilation at psi(3770) resonance
Abstract We report measurements of the line shapes of D + D − , D 0 D ¯ 0 and D D ¯ production as well as the line shape of the ratio of the production rates of D + D − and D 0 D ¯ 0 in e + e − annihilation at ψ ( 3770 ) resonance. We find that the line shapes of D + D − , D 0 D ¯ 0 and D D ¯ production are similar to an anomalous line shape of cross sections for e + e − → hadrons observed in the center-of-mass energy range from 3.70 to 3.87 GeV.
7776635
Measurements of the continuum R(uds) and R values in e(+)e(-) annihilation in the energy region between 3.650 and 3.872 GeV.
We report measurements of the continuum R(uds) near the center-of-mass energy of 3.70 GeV, the R[uds(c)+psi(3770)](s) and the R(had)(s) values in e(+)e(-) annihilation at 68 energy points in the energy region between 3.650 and 3.872 GeV with the BES-II detector at the BEPC Collider. We obtain the R(uds) for the continuum light hadron (containing u, d, and s quarks) production near the DD threshold to be R(uds)=2.141+/-0.025+/-0.085.
119257183
Observation of the decay $\psi(3686)$ $\rightarrow$ $\Lambda\bar\Sigma^{\pm}\pi^{\mp}+c.c.$
Using a sample of $1.06\times10^{8}$ $\psi(3686)$ events collected with the BESIII detector, we present the first observation of the decays of $\psi(3686)$ $\rightarrow$ $\Lambda\bar\Sigma^{+}\pi^{-}+c.c.$ and $\psi(3686)$ $\rightarrow$ $\Lambda\bar\Sigma^{-}\pi^{+}+c.c.$. The branching fractions are measured to be $\mathcal{B}(\psi(3686) \rightarrow \Lambda\bar\Sigma^{+}\pi^{-} + c.c.)=(1.40\pm 0.03 \pm 0.13)\times10^{-4}$ and $\mathcal{B}(\psi(3686) \rightarrow \Lambda\bar\Sigma^{-}\pi^{+}+c.c.)=(1.54\pm 0.04 \pm 0.13)\times10^{-4}$, where the first errors are statistical and the second ones systematic.
118073401
Observation of $\eta_{c}$ decay into $\Sigma^{+}\bar{\Sigma}^{-}$ and $\Xi^{-}\bar{\Xi}^{+}$ final states
Using a data sample of $2.25\times10^{8}$ $J/\psi$ events collected with the BESIII detector, we present the first observation of the decays of $\eta_{c}$ mesons to $\Sigma^{+}\bar{\Sigma}^{-}$ and $\Xi^{-}\bar{\Xi}^{+}$. The branching fractions are measured to be $(2.11\pm0.28_{\rm stat.}\pm0.18_{\rm syst.}\pm0.50_{\rm PDG})\times10^{-3}$ and $(0.89\pm0.16_{\rm stat.}\pm0.08_{\rm syst.}\pm0.21_{\rm PDG})\times10^{-3}$ for $\eta_{c} \to \Sigma^{+}\bar{\Sigma}^{-}$ and $\Xi^{-}\bar{\Xi}^{+}$, respectively. These branching fractions provide important information on the helicity selection rule in charmonium-decay processes.