Wed·Sep 13, 2017Wednesday·September 13, 2017

1. 01*

   Collective long-range particle correlations in proton-proton and proton-nucleus collisions at the LHC with the CMS detector

   Zhenyu Chen🇺🇸

   Measurements of two-particle angular correlations of inclusive charged particles as well as identified strange hadron in pp and pPb collisions are presented over a wide range in pseudorapidity and full azimuth. The data were collected using the CMS detector at the LHC, with nucleon-nucleon center-of-mass energy of 5.02 TeV for pPb collisions and 5, 7, 13 TeV for pp collisions. The results are compared to semi-peripheral PbPb collision data at center-of-mass energy of 2.76 TeV, covering similar charged-particle multiplicity ranges of the events. For high-multiplicity pp and pPb events, a clear particle species dependence of $v_2$ is observed for $p_T\lesssim 2$ GeV/c. When divided by the number of constituent quarks and compared at the same transverse kinetic energy per quark, a universal scaling over a broad range of particle transverse kinetic energy has been observed. For high-multiplicity pp collisions at 13 TeV, the $v_2$ values obtained for inclusive charged particles with two-, four- and six-particle correlations are found to be comparable within uncertainties. These measurements provide strong evidence for the collective nature of the long-range correlations observed in pp collisions.

   nucl-exhep-exhep-phnucl-th1 citation
2. 02*

   Testing microscopically derived descriptions of nuclear collectivity: Coulomb excitation of 22Mg

   J. Henderson · G. Hackman · P. Ruotsalainen · S. R. Stroberg · K. D. Launey · F. A. Ali · N. Bernier · M. A. Bentley · M. Bowry · R. Cabellero-Folch · L. J. Evitts · R. Frederick and 15 other authors

   Many-body nuclear theory utilizing microscopic or chiral potentials has developed to the point that collectivity might be dealt with in an {\it ab initio} framework without the use of effective charges; for example with the proper evolution of operators, or alternatively, through the use of an appropriate and manageable subset of particle-hole excitations. We present a precise determination of $E2$ strength in ${}^{22}$Mg and its mirror ${}^{22}$Ne by Coulomb excitation, allowing for rigorous comparisons with theory. No-core symplectic shell-model calculations were performed and agree with the new $B(E2)$ values while in-medium similarity-renormalization-group calculations consistently underpredict the absolute strength, with the missing strength found to have both isoscalar and isovector components.

   nucl-exPLB(2018)·71 citations
3. 03*

   Approach to equilibrium of quarkonium in quark-gluon plasma

   Xiaojun Yao🇺🇸 · Berndt Müller🇺🇸

   We calculate the dissociation and recombination rates of ${\rm Y}(1S)$ in quark-gluon plasma by using potential non-relativistic QCD. We then study the dynamical in-medium evolution of the $b\bar{b}-{\rm Y}$ system in a periodic box via the Boltzmann equation and explore how the system reaches equilibrium. We find that interactions between the free heavy quarks and the medium are necessary for the system to reach equilibrium. We find that the angular distribution of ${\rm Y}(1S)$ probes the stages at which recombination occurs. Finally, we study the system under a longitudinal expansion and show that different initial conditions evolve to distinct final ratios of hidden and open $b$ flavors. We argue that experimental measurements of the ratio could address open questions in the quarkonium production in heavy ion collisions.

   ↳ hep-phhep-exnucl-exnucl-thPRC(2018)·65 citations
4. 04*

   Quasiparticle-vibration coupling effects on nuclear transitions of astrophysical interest

   Caroline Robin🇺🇸 · Elena Litvinova🇺🇸

   The relativistic quasiparticle time-blocking approximation (RQTBA) is applied to the description of nuclear excitation modes of astrophysical interest. This method is based on the meson-nucleon Lagrangian and goes beyond the standard relativistic quasiparticle random-phase approximation (RQRPA) by treating the coupling between single quasiparticles and collective vibrations of the nucleus. We calculate electric dipole transitions and Gamow-Teller modes in the (p,n) direction in a few Sn isotopes and obtain the rates of (n,$\gamma$) reaction and ${\beta }^{-}$-decay processes, which govern the r-process nucleosynthesis, in a unified RQTBA framework. Gamow-Teller transitions in the (n,p) branch, which in principle can serve for the modeling of stellar evolution, are also investigated, and ${}^{90}$Zr is taken as a study case.

   ↳ nucl-thnucl-exAIP Conf.Proc.(2017)·3 citations
5. 05*

   Charge-exchange quasi-elastic process $nd\to p(nn)$ under $0^{\circ }$ in the frame of elastic $np\to np$ scattering to $180^{\circ }$

   R. A. Shindin🇷🇺 · D. K. Guriev🇷🇺 · A. N. Livanov🇷🇺 · I. P. Yudin

   It is considered the problem of spin physics related with the difference of representation of the elastic interaction between the neutron and proton. In the first case the charge-exchange reaction $np\to pn$ under the angle $\theta$ is supposed, in the second --- the simple elastic scattering of $np\to np$, when the neutron is going in opposite direction $\pi -\theta$. The transition from one representation to another is provided by the Majorana operator. In the framework of impulse approximation it is twice calculated the quasi-elastic charge-exchange reaction of a neutron on a deuteron. In the frame of $nd\to p(nn)$ scattering of proton to the angle $\theta$ it gives the well-known Dean formula. Using other representation $nd\to (nn)p$ as a neutron elastic scattering under the angle $\pi -\theta$ (together with neutron-spectator in $nn$-pair) the alternative formula is presented.

   ↳ nucl-thnucl-ex0 citations
6. 06*

   Distillation of scalar exchange by coherent hypernucleus production in antiproton-nucleus collisions

   A.B. Larionov🇩🇪 · H. Lenske🇩🇪

   The total and angular differential cross sections of the coherent process $\bar{p}+{}^{A}Z\to {}_{\Lambda }^A(Z-1)+\bar{\Lambda }$ are evaluated at the beam momenta $1.5÷20$ GeV/c within the meson exchange model with bound proton and $\Lambda$-hyperon wave functions. It is shown that the shape of the beam momentum dependence of the hypernucleus production cross sections with various discrete $\Lambda$ states is strongly sensitive to the presence of the scalar $\kappa$-meson exchange in the $\bar{p}p\to \bar{\Lambda }\Lambda$ amplitude. This can be used as a clean test of the exchange by scalar $\pi K$ correlation in coherent $\bar{p}A$ reactions.

   ↳ nucl-thhep-exhep-phnucl-exPLB(2017)·6 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.