Thu·Dec 21, 2017Thursday·December 21, 2017

1. 01*

   Super-Rosenbluth Measurements with Electrons and Positrons

   Mikhail Yurov🇺🇸 · John Arrington🇺🇸

   Precise measurements of the proton form factor ratio mu*GE/GM from Rosenbluth separation measurements can be combined with Polarization based extractions to provide significant constraints on two-photon exchange contributions to the elastic e-p cross section. We present an overview of JLab experiment E05-017, the high-precision Super-Rosenbluth measurements of the proton form factor taken in Hall C of Jefferson Lab. We then examine what precision could be obtained for Super-Rosenbluth measurements using a low-intensity positron beam at Jefferson Lab.

   nucl-exAIP Conf.Proc.(2018)·3 citations
2. 02*

   Searching for Hybrid Mesons with GlueX

   Sean Dobbs (for the GlueX Collaboration)🇺🇸

   Hybrid mesons consist of a quark-antiquark pair bound together by a gluonic field that is in an excited state. Measuring the spectrum of these states will provide valuable information on the gluonic degrees of freedom of QCD in the quark-confinement regime. A rich spectrum of hybrid meson states has been predicted, but only a few experiments have reported evidence of their existence. The GlueX experiment at Jefferson Lab is designed to search for and measure the spectrum of light-mass hybrid mesons, and it has began its physics run in Spring 2017. For the experiment, a 12 GeV electron beam incident on a diamond radiator is used to produce a linearly-polarized, coherent bremsstrahlung tagged-photon beam with a coherent peak at 9 GeV. The linearly-polarized photon beam is incident on a proton target located within the hermetic GlueX detector, which can detect many different final states to which the hybrid mesons are predicted to decay. Measurements with these initial data are discussed, including beam asymmetry measurements, the search for photoproduced $\Xi$ baryons, and near-threshold charm production.

   nucl-exhep-exPoS(2018)·8 citations
3. 03*

   $N^{\ast }$ resonances from $K\Lambda$ amplitudes in sliced bins in energy

   A.V. Anisovich🇩🇪 · V. Burkert🇺🇸 · M. Hadžimehmedović🇧🇦 · D.G. Ireland🇬🇧 · E. Klempt🇩🇪 · V.A. Nikonov🇩🇪 · R. Omerović🇧🇦 · A.V. Sarantsev🇩🇪 · J. Stahov🇧🇦 · A. Švarc🇭🇷 · U. Thoma🇩🇪

   The two reactions $\gamma p\to K^{+}\Lambda$ and ${\pi }^{-}p\to K^0\Lambda$ are analyzed to determine the leading photoproduction multipoles and the pion-induced partial wave amplitudes in slices of the invariant mass. The multipoles and the partial-wave amplitudes are simultaneously fitted in a multichannel Laurent+Pietarinen model (L+P model), which determines the poles in the complex energy plane on the second Riemann sheet close to the physical axes. The results from the L+P fit are compared with the results of an energy-dependent fit based on the Bonn-Gatchina (BnGa) approach. The study confirms the existence of several poles due to nucleon resonances in the region at about 1.9\,GeV with quantum numbers $J^P=1/2^{+}$, $3/2^{+},1/2^{-},3/2^{-},5/2^{-}$.

   nucl-exEPJA(2017)·20 citations
4. 04*

   Strong evidence for nucleon resonances near 1900\,MeV

   A.V. Anisovich🇩🇪 · V. Burkert🇺🇸 · M. Hadžimehmedović🇧🇦 · D.G. Ireland🇬🇧 · E. Klempt🇩🇪 · V.A. Nikonov🇩🇪 · R. Omerović🇧🇦 · H. Osmanović🇧🇦 · A.V. Sarantsev🇩🇪 · J. Stahov🇧🇦 · A. Švarc🇭🇷 · U. Thoma🇩🇪

   Data on the reaction $\gamma p\to K^{+}\Lambda$ from the CLAS experiments are used to derive the leading multipoles, $E_{0+}$, $M_{1-}$, $E_{1+}$, and $M_{1+}$, from the production threshold to 2180\,MeV in 24 slices of the invariant mass. The four multipoles are determined without any constraints. The multipoles are fitted using a multichannel $L+P$ model which allows us to search for singularities and to extract the positions of poles on the complex energy plane in an almost model-independent method. The multipoles are also used as additional constraints in an energy-dependent analysis of a large body of pion and photo-induced reactions within the Bonn-Gatchina (BnGa) partial wave analysis. The study confirms the existence of poles due to nucleon resonances with spin-parity $J^P=1/2^{-};1/2^{+}$, and $3/2^{+}$ in the region at about 1.9\,GeV.

   nucl-exPRL(2017)·44 citations
5. 05*

   First Determination of Level Structure of an $sd$-Shell Hypernucleus, ${}_{\mathrm{\Lambda }}^{19}\mathrm{F}$

   S. B. Yang🇨🇳 · J. K. Ahn🇰🇷 · Y. Akazawa🇰🇷 · K. Aoki🇯🇵 · N. Chiga🇯🇵 · H. Ekawa🇯🇵 · P. Evtoukhovitch🇯🇵 · A. Feliciello🇮🇹 · M. Fujita🇮🇹 · S. Hasegawa🇯🇵 · S. Hayakawa🇯🇵 · T. Hayakawa🇯🇵 and 36 other authors

   We report on the first observation of $\gamma$ rays emitted from an $sd$-shell hypernucleus, ${}_{\mathrm{\Lambda }}^{19}\mathrm{F}$. The energy spacing between the ground state doublet, $1/2^{+}$ and $3/2^{+}$ states, of ${}_{\mathrm{\Lambda }}^{19}\mathrm{F}$ is determined to be $315.5\pm 0.4(\mathrm{stat}{)}_{-0.5}^{+0.6}(\mathrm{syst})\mathrm{keV}$ by measuring the $\gamma$-ray energy from the $M1(3/2^{+}\to 1/2^{+})$ transition. In addition, three $\gamma$-ray peaks were observed and assigned as $E2(5/2^{+}\to 1/2^{+})$, $E1(1/2^{-}\to 1/2^{+})$, and $E1(1/2^{-}\to 3/2^{+})$ transitions. The excitation energies of the $5/2^{+}$ and $1/2^{-}$ states are determined to be $895.2\pm 0.3(\mathrm{stat})\pm 0.5(\mathrm{syst})\mathrm{keV}$ and $1265.6\pm 1.2(\mathrm{stat}{)}_{-0.5}^{+0.7}(\mathrm{syst})\mathrm{keV}$, respectively. It is found that the ground state doublet spacing is well described by theoretical models based on existing $s$- and $p$-shell hypernuclear data.

   nucl-exPRL(2018)·21 citations
6. 06*

   In-Medium $K^{+}$ Electromagnetic Form Factor with a Symmetric Vertex in a Light Front Approach

   George H. S. Yabusaki (Instituto Tecnológico de Aeronáutica - ITA and LFTC - Cruzeiro do Sul)🇧🇷 · J. P. B. C. de Melo (LFTC - Cruzeiro do Sul)🇧🇷 · Wayne de Paula (Instituto Tecnológico de Aeronáutica - ITA)🇧🇷 · K. Tsushima (LFTC - Cruzeiro do Sul)🇧🇷 · T. Frederico (Instituto Tecnológico de Aeronáutica - ITA)🇧🇷

   Using the light-front kaon wave function based on a Bethe-Salpeter amplitude model for the quark-antiquark bound state, we study the Electromagnetic Form Factor (EMFF) of the kaon in nuclear medium within the framework of light-front field theory. The kaon model we adopt is well constrained by previous and recent studies to explain its properties in vacuum. The in-medium kaon EMFF is evaluated for the + component of the electromagnetic current, $J^{+}$, in the Breit frame. In order to consistently incorporate the constituent up and antistrange quarks of the kaon immersed in symmetric nuclear matter, we use the Quark-Meson Coupling (QMC) model, which has been widely applied to various hadronic and nuclear phenomena in a nuclear medium with success. We predict the in-medium modification of the kaon EMFF in symmetric nuclear matter. It is found that, after a fine tuning of the regulator mass, i.e. $m_R=0.600$ GeV, the model is suitable to fit the available experimental data in vaccum within the theoretical uncertainties, and based on this we predict the in-medium modification of the EMFF.

   ↳ hep-phhep-exnucl-exnucl-thFew Body Syst.(2018)·7 citations
7. 07*

   Study of Bose-Einstein correlations in pp, pPb, and PbPb collisions at $\sqrt{s_{\mathrm{NN}}}=$ 0.9-7 TeV

   CMS Collaboration

   Quantum statistical (Bose-Einstein) two-particle correlations are measured in pp collisions at $\sqrt{s}=$ 0.9, 2.76, and 7 TeV, as well as in pPb and peripheral PbPb collisions at nucleon-nucleon center-of-mass energies of 5.02 and 2.76 TeV, respectively, using the CMS detector at the LHC. Separate analyses are performed for same-sign unidentified charged particles as well as for same-sign pions and kaons identified via their energy loss in the silicon tracker. The characteristics of the one-, two-, and three-dimensional correlation functions are studied as functions of the pair average transverse momentum ($k_{\mathrm{T}}$) and the charged-particle multiplicity in the event. For all systems, the extracted correlation radii steadily increase with the event multiplicity, and decrease with increasing $k_{\mathrm{T}}$. The radii are in the range 1-5 fm, the largest values corresponding to very high multiplicity pPb interactions and to peripheral PbPb collisions with multiplicities similar to those seen in pPb data. It is also observed that the dependencies of the radii on multiplicity and $k_{\mathrm{T}}$ largely factorize. At the same multiplicity, the radii are relatively independent of the colliding system and center-of-mass energy.

   ↳ hep-exnucl-exPRC(2018)·74 citations
8. 08*

   Experimental Overview of Light Mesons

   Sean Dobbs🇺🇸

   The light quark $uds$ mesons have been a foundation of our understanding of the strong interaction for decades. New experiments with modern detectors and large data sets are furthering our understanding of the spectrum and dynamics of these states. In this paper, I review several recent results on the spectroscopy of light mesons and discuss the future of this field.

   ↳ hep-exnucl-exPoS(2018)·0 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.