# Preprints

 2017-05-3014:44 [GSI-2017-00764] Preprint/Report et al Measurement of the integrated luminosity and the center-of-mass energy of the data taken by BESIII at $\sqrt{s} = 2.125$ GeV [arXiv:1705.09722] To study the nature of the state $Y(2175)$, a dedicated data set of $e^+e^-$ collision data was collected at the center-of-mass energy of 2.125 GeV with the BESIII detector at the BEPCII collider. By analyzing large-angle Bhabha scattering events, the integrated luminosity of this data set is determined to be $108.49\pm0.02\pm0.75$~pb$^{-1}$, where the first uncertainty is statistical and the second one is systematic. [...] 2017-05-3014:40 [GSI-2017-00763] Preprint/Report et al Evidence for $e^{+}e^{-} \to \gamma\eta_c(1S)$ at center-of-mass energies between 4.01 and 4.60 GeV [arXiv:1705.06853] We present first evidence for the process $e^+e^-\to \gamma\eta_c(1S)$ at six center-of-mass energies between 4.01 and 4.60~GeV using data collected by the BESIII experiment operating at BEPCII. These data sets correspond to a total integrated luminosity of 4.6~fb$^{-1}$. [...] 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. [...]