Fri·Aug 19, 2016Friday·August 19, 2016

1. 01*

   A novel probe of chiral restoration in nuclear medium

   Philipp Gubler🇰🇷 · Teiji Kunihiro🇯🇵 · Su Houng Lee🇰🇷

   We propose measuring the mass shift and width broadening of the $f_1(1285)$ meson together with those of the $\omega$ from a nuclear target as a means to experimentally probe the partial restoration of chiral symmetry inside the nuclear matter. The relation between the order parameter of chiral symmetry and the difference in the correlation functions of the $f_1(1285)$ current and the $\omega$ current is discussed in the limit where the disconnected diagrams are neglected. A QCD sum rule analysis of the $f_1(1285)$ meson mass leads to about 100 MeV attraction in nuclear matter, which can be probed in future experiments.

   ↳ nucl-thhep-phnucl-exPLB(2017)·22 citations
2. 02*

   Semihadronic and hadronic decays of ${\rho }^0$ and $\omega$ mesons coherently photoproduced in the isoscalar nuclei

   Swapan Das🇮🇳

   The interference of the ${\rho }^0$ and $\omega$ mesons has been studied in the hadronic and leptonic decay channels, i.e., dipion and dilepton decay channels respectively, but this interference is not studied yet in the semihadronic or semileptonic decay channel, e.g., $V\to {\pi }^0\gamma$. $V$ denotes either ${\rho }^0$ or $\omega$ meson. To look for the quoted interference in the ${\pi }^0\gamma$ decay channel as well as the contribution of $\rho$ meson to the cross section, the correlated ${\pi }^0\gamma$ invariant mass distribution spectra are calculated in the photonuclear reaction in the multi-GeV region. It is assumed that these bosons arise in the final state due to the decay of ${\rho }^0$ and $\omega$ mesons which are photoproduced coherently in the isoscalar nucleus. The elementary reaction in the nucleus is considered to proceed as $\gamma N\to VN$; $V\to {\pi }^0\gamma$. The forward propagation of the $\rho$ and $\omega$ mesons and the near forward emission of pion are considered, so that they can be described by the eikonal form. The meson nucleus interactions are evaluated using $t\varrho$ approximation. Replacing the decay vertex $V\to {\pi }^0\gamma$ by $V\to {\pi }^{+}{\pi }^{-}$ in the above formalism, it is also used to study the $\rho -\omega$ interference in the ${\pi }^{+}{\pi }^{-}$ decay channel.

   ↳ nucl-thnucl-exPRC(2016)·3 citations
3. 03*

   Thermal Electromagnetic Radiation in Heavy-Ion Collisions

   R. Rapp🇺🇸 · H. van Hees🇩🇪

   We review the potential of precise measurements of electromagnetic probes in relativistic heavy-ion collisions for the theoretical understanding of strongly interacting matter. The penetrating nature of photons and dileptons implies that they can carry undistorted information about the hot and dense regions of the fireballs formed in these reactions and thus provide a unique opportunity to measure the electromagnetic spectral function of QCD matter as a function of both invariant mass and momentum. In particular we report on recent progress on how the medium modifications of the (dominant) isovector part of the vector current correlator ($\rho$ channel) can shed light on the mechanism of chiral symmetry restoration in the hot and/or dense environment. In addition, thermal dilepton radiation enables novel access to (a) the fireball lifetime through the dilepton yield in the low invariant-mass window $0.3\mathrm{GeV}\le M\le 0.7\mathrm{GeV}$, and (b) the early temperatures of the fireball through the slope of the invariant-mass spectrum in the intermediate-mass region ($1.5\mathrm{GeV}<M<2.5\mathrm{GeV}$). The investigation of the pertinent excitation function suggests that the beam energies provided by the NICA and FAIR projects are in a promising range for a potential discovery of the onset of a first order phase transition, as signaled by a non-monotonous behavior of both low-mass yields and temperature slopes.

   ↳ hep-phnucl-exnucl-thEPJA(2016)·34 citations
4. 04*

   Correlations of flow harmonics in 2.76A TeV Pb--Pb collisions

   Xiangrong Zhu🇨🇳 · You Zhou🇩🇰 · Haojie Xu🇨🇳 · Huichao Song🇨🇳

   Using the event-by-event viscous hydrodynamics VISH2+1 with MC-Glauber, MC-KLN, and AMPT initial conditions, we investigate the correlations of flow harmonics, including the symmetric cumulants $S{C}^v(m,n)$, the normalized symmetric cumulants $NSC(m,n)$, and the Pearson correlation coefficients $C(v_m^2,v_n^2)$ in 2.76A TeV Pb--Pb collisions. We find $S{C}^v(m,n)$ is sensitive to both initial conditions and the specific shear viscosity $\eta /s$. A comparison with the recent ALICE data show that our hydrodynamic calculations can qualitatively describe the data of $S{C}^v(3,2)$ and $S{C}^v(4,2)$ for various initial conditions, which demonstrate that $v_2$, $v_4$ are correlated and $v_2$, $v_3$ are anti-correlated. Meanwhile, the predicted symmetric cumulants $S{C}^v(5,2)$, $S{C}^v(5,3)$, and $S{C}^v(4,3)$ reveal that $v_2$ and $v_5$, $v_3$ and $v_5$ are correlated, $v_3$ and $v_4$ are anti-correlated in most centrality classes. We also find $NS{C}^v(3,2)$ and $C(v_3^2,v_2^2)$, which are insensitive to $\eta /s$, are mainly determined by corresponding $NS{C}^{\epsilon }(3,2)$ and $C({\epsilon }_3^2,{\epsilon }_2^2)$ correlators from the initial state. In contrast, other $NS{C}^v(m,n)$ and $C(v_m^2,v_n^2)$ correlators are influenced by both initial conditions and $\eta /s$, which illustrates the non-linear mode couplings in higher flow harmonics with $n\ge 4$.

   ↳ nucl-thhep-phnucl-exPRC(2017)·68 citations
5. 05*

   Determination of the extraction efficiency for ${}^{233}$U source $\alpha$-recoil ions from the MLL buffer-gas stopping cell

   Lars von der Wense · Benedict Seiferle · Mustapha Laatiaoui🇩🇪 · Peter G. Thirolf

   Following the $\alpha$ decay of ${}^{233}$U, ${}^{229}$Th recoil ions are shown to be extracted in a significant amount from the MLL buffer-gas stopping cell. The produced recoil ions and subsequent daughter nuclei are mass purified with the help of a customized quadrupole mass spectrometer. The combined extraction and mass-purification efficiency for ${}^{229}$Th${}^{3+}$ is determined via MCP-based measurements and via the direct detection of the ${}^{229}$Th $\alpha$ decay. A large value of $(10\pm 2)$\% for the combined extraction and mass-purification efficiency of ${}^{229}$Th${}^{3+}$ is obtained at a mass resolution of about 1 u/e. In addition to ${}^{229}$Th, also other $\alpha$-recoil ions of the ${}^{233,232}$U decay chains are addressed.

   ↳ physics.ins-detnucl-exEPJA(2015)·19 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.