121480444
Recent results from BNL E865
Experiment E865 at the BNL AGS is a search for the Lepton Family Violating decay K+→π+μ+e−1. We aim to reach a single event sensitivity below 10−11 for this decay. The E865 apparatus allow us to collect and study other rare and semi rare K+ decays. Preliminary results are shown on K+→π+μ+e−, K+→π+e+e−, K+→π+μ+μ−, K+→π+π−e+ν, K+→e+νe+e−, K+→μ+νe+e−, K+→π0e+ν (π0→e+e−γ).
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.
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.
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 ...
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
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.
118168382
First observation of the isospin violating decay $J/\psi\rightarrow \Lambda\bar{\Sigma}^{0}+c.c.$
Using a sample of $(225.2\pm 2.8)\times 10^6$ $J/\psi$ events collected with the BESIII detector, we present results of a study of $J/\psi\rightarrow \gamma\Lambda\bar{\Lambda}$ and report the first observation of the isospin violating decay $J/\psi\rightarrow\Lambda\bar{\Sigma}^{0}+c.c.$, in which $\bar{\Sigma}^{0}$ decays to $\gamma \bar{\Lambda}$. The measured branching fractions are $\mathcal{B}(J/\psi\rightarrow\bar{\Lambda}\Sigma^{0}$) = $(1.46\pm0.11\pm0.12) \times10^{-5}$ and $\mathcal{B}(J/\psi\rightarrow\Lambda\bar{\Sigma^{0}}$) = $(1.37\pm0.12\pm0.11) \times10^{-5}$. We search for $\Lambda(1520) \rightarrow \gamma \Lambda$ decay, and find no evident signal, and an upper limit for the product branching fraction $\mathcal{B}(J/\psi\rightarrow\Lambda\bar{\Lambda}(1520)+c.c.)\times \mathcal{B}(\Lambda(1520)\rightarrow\gamma\Lambda)<4.1 \times10^{-6}$ is set at the 90% confidence level. We also report the observation of $\eta_{c}\rightarrow\Lambda\bar{\Lambda}$ in $J/\psi \rightarrow \gamma \eta_{c}$, $\eta_{c}\rightarrow\Lambda\bar{\Lambda}$ and measure the branching fraction $\mathcal{B}(\eta_{c}\rightarrow\Lambda\bar{\Lambda}) =(1.16\pm0.12 (stat)\pm0.19(syst)\pm0.28(PDG))\times10^{-3}$.
120160020
Interference effects between the initial and final state radiation in a QCD medium
Coherence between multiple emitters is one of the most remarkable properties of QCD jet physics in vacuum. In the presence of a QCD medium one expects that the coherence pattern between multiple emitters is affected. In this work we calculate the gluon emission spectrum off an asymptotic quark traversing a dilute QCD medium. When interferences between initial and final quark are included, the medium induced gluon distribution gets modified. The coherent, incoherent and soft limit of the medium induced spectrum are studied. In the soft limit we find an elegant and intuitive probabilistic interpretation. We comment on possible phenomenological applications of this setup for studying coherence effects on observables studied in high energy nuclear collisions.
38323494
Search for the Lepton Flavor Violation Process J/ψ→eμ at BESIII
We search for the lepton-flavor-violating decay of the J/psi into an electron and a muon using (225.3 +/- 2.8) x 10(6) J/psi events collected with the BESIII detector at the BEPCII. Four candidate events are found in the signal region, consistent with background expectations. An upper limit on the branching fraction of B(J/psi -> e mu) <1.6 x 10(-7) (90% C.L.) is obtained.
125685455
First observation of J / psi and psi(2S) decaying to n K0(S) anti-Lambda + c.c