# Preprints

 2017-05-3014:34 [GSI-2017-00762] Preprint/Report et al Dark Photon Search in the Mass Range Between 1.5 and 3.4 GeV/$c^2$612 [arXiv:1705.04265] Using a data set of 2.93 fb$^{-1}$ taken at a center-of-mass energy $\sqrt{s}$ = 3.773 GeV with the BESIII detector at the BEPCII collider, we perform a search for an extra U(1) gauge boson, also denoted as a dark photon. We examine the initial state radiation reactions $e^+e^-\rightarrow e^+e^-\gamma_{\rm ISR}$ and $e^+e^-\rightarrow \mu^+\mu^-\gamma_{\rm ISR}$ for this search, where the dark photon would appear as an enhancement in the invariant mass distribution of the leptonic pairs. [...] 2017-05-3014:22 [GSI-2017-00760] Preprint/Report et al Observation of $e^{+}e^{-} \to \eta h_{c}$ at center-of-mass energies from 4.085 to 4.600 GeV [arXiv:1704.08033 ] We observe for the first time the process $e^{+}e^{-} \rightarrow \eta h_c$ with data collected by the BESIII experiment. Significant signals are observed at the center-of-mass energy $\sqrt{s}=4.226$ GeV, and the Born cross section is measured to be $(9.5^{+2.2}_{-2.0} \pm 2.7)$ pb. [...] 2017-05-3014:20 [GSI-2017-00759] Preprint/Report Peters, K. Technical Design Report for the Panda Forward Spectrometer Calorimeter [arXiv:1704.02713 ] This document is devoted to the electromagnetic calorimeter of the Forward Spectrometer and describes the design considerations, the technical layout, the expected performance, and the production readiness.. 2017-05-3014:00 [GSI-2017-00758] Preprint/Report et al Analysis of $D^+\to\bar K^0e^+\nu_e$ and $D^+\to\pi^0e^+\nu_e$ Semileptonic Decays [arXiv:1703.09084] Using 2.93~fb$^{-1}$ of data taken at 3.773 GeV with the BESIII detector operated at the BEPCII collider, we study the semileptonic decays $D^+ \to \bar K^0e^+\nu_e$ and $D^+ \to \pi^0 e^+\nu_e$. We measure the absolute decay branching fractions $\mathcal B(D^+ \to \bar K^0e^+\nu_e)=(8.60\pm0.06\pm 0.15)\times10^{-2}$ and $\mathcal B(D^+ \to \pi^0e^+\nu_e)=(3.63\pm0.08\pm0.05)\times10^{-3}$, where the first uncertainties are statistical and the second systematic. [...] 2017-05-3013:57 [GSI-2017-00757] Preprint/Report et al Measurement of $e^{+}e^{-}\rightarrow \pi^{+}\pi^{-}\psi(3686)$ from 4.008 to 4.600~GeV and observation of a charged structure in the $\pi^{\pm}\psi(3686)$ mass spectrum [arXiv:1703.08787 ] We study the process $e^{+}e^{-}\rightarrow \pi^{+}\pi^{-}\psi(3686)$, based on 5.1~fb$^{-1}$ of data collected at 16 center-of-mass energy ($\sqrt{s}$) points from 4.008 to 4.600 GeV with the BESIII detector operating at the BEPCII collider. The measured Born cross sections for $e^{+}e^{-}\rightarrow \pi^{+}\pi^{-}\psi(3686)$ are consistent with previous results, but with much improved precision. [...] 2017-05-3013:55 [GSI-2017-00756] Preprint/Report et al Branching fraction measurements of $\psi(3686) \to \gamma \chi_{cJ}$ [arXiv:1703.00077 ] Using a sample of 106 million $\psi(3686)$ decays, the branching fractions of $\psi(3686) \to \gamma \chi_{c0}, \psi(3686) \to \gamma \chi_{c1}$, and $\psi(3686) \to \gamma \chi_{c2}$ are measured with improved precision to be $(9.389 \pm 0.014 \pm 0.332)\,\%$, $(9.905 \pm 0.011 \pm 0.353)\,\%$, and $(9.621 \pm 0.013 \pm 0.272)\,\%$, respectively, where the first uncertainties are statistical and the second ones are systematic. The product branching fractions of $\psi(3686) \to \gamma \chi_{c1}, \chi_{c1} \to \gamma J/\psi$ and $\psi(3686) \to \gamma \chi_{c2}, \chi_{c2} \to \gamma J/\psi$ and the branching fractions of $\chi_{c1} \to \gamma J/\psi$ and $\chi_{c2} \to \gamma J/\psi$ are also presented.. 2017-05-3013:52 [GSI-2017-00755] Preprint et al Evidence for the singly-Cabibbo-suppressed decay $\Lambda_{c}^{+} \to p\eta$ and search for $\Lambda_{c}^{+} \to p\pi^{0}$ We study the singly-Cabibbo-suppressed decays $\Lambda_c^{+}\to p\eta$ and $\Lambda_{c}^{+}\to p\pi^{0}$ using $\Lambda_{c}^{+}\Lambda_{c}^{+}$ pairs produced by $e^+e^-$ collisions at a center-of-mass energy of $\sqrt{s} = 4.6\; GeV$. The data sample was collected by the BESIII detector at the BEPCII collider and corresponds to an integrated luminosity of 567 $pb^{-1}$. [...] 2017-05-3013:49 [GSI-2017-00754] Preprint/Report et al Luminosity measurements for the R scan experiment at BESIII [arXiv:1702.04977 ] By analyzing the large-angle Bhabha scattering events $e^{+}e^{-}$ $\to$ ($\gamma$)$e^{+}e^{-}$ and diphoton events $e^{+}e^{-}$ $\to$ $\gamma\gamma$ for the data sets collected at center-of-mass (c.m.) energies between 2.2324 and 4.5900 GeV (131 energy points in total) with the upgraded Beijing Spectrometer (BESIII) at the Beijing Electron-Positron Collider (BEPCII), the integrated luminosities have been measured at the different c.m. energies, individually. [...] 2017-05-3013:43 [GSI-2017-00753] Preprint/Report et al Observation of $\psi(3686) \rightarrow e^{+}e^{-}\chi_{cJ}$ and $\chi_{cJ} \rightarrow e^{+}e^{-}J/\psi$ [1701.05404 ] Using $4.479 \times 10^{8}$ $\psi(3686)$ events collected with the BESIII detector, we search for the decays $\psi(3686) \rightarrow e^{+}e^{-}\chi_{c0,1,2}$ and $\chi_{c0,1,2} \rightarrow e^{+}e^{-}J/\psi$. The decays $\psi(3686) \rightarrow e^{+}e^{-}\chi_{c0,1,2}$ and $\chi_{c0,1,2} \rightarrow e^{+}e^{-}J/\psi$ are observed for the first time. [...] 2017-01-3116:09 [GSI-2017-00323] Preprint et al Feasibility studies of time-like proton electromagnetic form factors at PANDA at FAIR Simulation results for future measurements of electromagnetic proton form factors at \PANDA (FAIR) within the PandaRoot software framework are reported. The statistical precision with which the proton form factors can be determined is estimated. [...]