Tue·Nov 15, 2016Tuesday·November 15, 2016

1. 01*

   Nuclear Fusion in Laser-Driven Counter-Streaming Collisionless Plasmas

   Xiaopeng Zhang · Jiarui Zhao · Dawei Yuan · Changbo Fu🇨🇳 · Jie Bao🇨🇳 · Liming Chen · Jianjun He🇨🇳 · Long Hou · Liang Li · Yanfei Li🇺🇸 · Yutong Li🇹🇼 · Guoqiang Liao and 8 other authors

   Nuclear fusion reactions are the most important processes in nature to power stars and produce new elements, and lie at the center of the understanding of nucleosynthesis in the universe. It is critically important to study the reactions in full plasma environments that are close to true astrophysical conditions. By using laser-driven counter-streaming collisionless plasmas, we studied the fusion D$+$D$\to n{+}^3$He in a Gamow-like window around 27 keV. The results show that astrophysical nuclear reaction yield can be modulated significantly by the self-generated electromagnetic fields and the collective motion of the plasma. This plasma-version mini-collider may provide a novel tool for studies of astrophysics-interested nuclear reactions in plasma with tunable energies in earth-based laboratories.

   nucl-exastro-ph.IMphysics.plasm-phPRC(2017)·11 citations
2. 02*

   Neutron-antineutron oscillations beyond the quasi-free limit

   E. David Davis🇺🇸 · Albert R. Young🇺🇸

   Prompted by plans to conduct a new neutron oscillation experiment at the European Spallation Source (ESS), we consider issues associated with the magnetic field that must be present, some of which are potentially exacerbated by the significantly larger length $l$ contemplated for the neutron propagation region. To this end, we introduce a stochastic model of the residual magnetic field within the propagation region which draws on features of magnetic profiles measured during the last free neutron oscillation experiment [conducted at the Institut Laue-Langevin (ILL) in the 1990's]. We average over both fluctuations in the magnetic field sampled by neutrons, and representative spectra of neutron speeds. We find that deviations from the quasi-free result for the antineutron probability do not depend quadratically on $l$ (as a naive perturbative estimate would suggest) but increase only linearly with $l$. As regards the large spikes in the magnetic field which can be expected at, for example, joints in the magnetic shielding of the propagation region (despite compensating currents and magnetic idealization of the shield), we demonstrate that their effect scales as $l/D^{3/2}$, where $D$ is the diameter of the cylindrical magnetic shielding. Our arguments suggest that, provided the dimensions of the propagation region are such that the ratio $l/D^{3/2}$ does not exceed the value pertinent to the ILL experiment, and these spikes occur close to either end of the propagation region, they can be neglected. We also establish that any large magnetic field encountered after the propagation region is exited will not diminish the probability for antineutron detection. For the range of values of $l$ of most interest to the ESS experiment, it should suffice to improve on the level of magnetic suppression achieved at the ILL by a factor of two.

   nucl-exhep-exPRD(2017)·15 citations
3. 03*

   Performance studies of D-meson tagged jets in pp collisions at $\sqrt{s}=7\mathrm{TeV}$ with ALICE

   Salvatore Aiola (for the ALICE Collaboration)🇺🇸

   We present the current status of the measurement of jets that contain a D meson (D-tagged jets) with ALICE. D-meson candidates, identified via their hadronic decay channels, were combined with the other charged tracks reconstructed with the central tracking system, using the anti-$k_{\mathrm{T}}$ jet-finding algorithm. The yield of D-tagged jets was extracted through an invariant mass analysis of the D-meson candidates. A Monte Carlo simulation was used to determine the detector performance and validate the signal extraction techniques.

   nucl-exJ.Phys.Conf.Ser.(2017)·0 citations
4. 04*

   Estimation of Stopped Protons at Energies Relevant for a Beam Energy Scan at the BNL Relativistic Heavy-Ion Collider

   Dhananjaya Thakur🇮🇳 · Sunil Jakhar🇮🇳 · Prakhar Garg🇮🇳 · Raghunath Sahoo (Indian Institute of Technology Indore, India)🇮🇳

   The recent net-proton fluctuation results of the STAR (Solenoidal Tracker At RHIC) experiment from beam energy scan (BES) program at the BNL Relativistic Heavy Ion Collider (RHIC) have drawn much attention to exploring the QCD critical point and the nature of deconfinement phase transition. There has been much speculation that the non-monotonic behavior of $\kappa {\sigma }^2$ of the produced protons around $\sqrt{s_{\mathrm{NN}}}$ = 19.6 GeV in the STAR results may be due to the existence of QCD critical point. However, the experimentally measured proton distributions contain protons from heavy resonance decays, from baryon stopping and from direct production processes. These proton distributions are used to estimate the net-proton number fluctuation. Because it is difficult to disentangle the protons from the above-mentioned sources, it is better to devise a method which will account for the directly produced baryons (protons) to study the dynamical fluctuation at different center-of-mass energies. This is because, it is assumed that any associated criticality in the system could affect the particle production mechanism and hence the dynamical fluctuation in various conserved numbers. In the present work, we demonstrate a method to estimate the number of stopped protons at RHIC BES energies for central $0-5\%$ \auau collisions within STAR acceptance and discuss its implications on the net-proton fluctuation results.

   nucl-exhep-exhep-phnucl-thPRC(2017)·10 citations
5. 05*

   Wobbling motion in ${}^{135}$Pr within a collective Hamiltonian

   Q. B. Chen🇩🇪 · S. Q. Zhang🇨🇳 · J. Meng🇨🇳

   The recently reported wobbling bands in ${}^{135}$Pr are investigated by the collective Hamiltonian, in which the collective parameters, including the collective potential and the mass parameter, are respectively determined from the tilted axis cranking (TAC) model and the harmonic frozen alignment (HFA) formula. It is shown that the experimental energy spectra of both yrast and wobbling bands are well reproduced by the collective Hamiltonian. It is confirmed that the wobbling mode in ${}^{135}$Pr changes from transverse to longitudinal with the rotational frequency. The mechanism of this transition is revealed by analyzing the effective moments of inertia of the three principal axes, and the corresponding variation trend of the wobbling frequency is determined by the softness and shapes of the collective potential.

   ↳ nucl-thnucl-exPRC(2016)·27 citations
6. 06*

   Baryon-to-meson transition distribution amplitudes: formalism and models

   B. Pire🇫🇷 · K. Semenov-Tian-Shansky🇷🇺 · L. Szymanowski🇵🇱

   In specific kinematics, hard exclusive amplitudes may be factorized into a short distance dominated part computable in a perturbative way on the one hand, and universal, confinement related hadronic matrix elements on the other hand. The extension of this description to processes such as backward meson electroproduction and forward meson production in antiproton-nucleon scattering leads to define new hadronic matrix elements of three quark operators on the light cone, the nucleon-to-meson transition distribution amplitudes, which shed a new light on the nucleon structure.

   ↳ hep-phhep-exnucl-exnucl-thFew Body Syst.(2017)·3 citations
7. 07*

   Amplitude reconstruction from complete experiments and truncated partial-wave expansions

   R.L. Workman🇺🇸 · L. Tiator🇩🇪 · Y. Wunderlich🇩🇪 · M. Doering🇺🇸 · H. Haberzettl🇺🇸

   We compare the methods of amplitude reconstruction, for a complete experiment and a truncated partial wave analysis, applied to the photoproduction of pseudo-scalar mesons. The approach is pedagogical, showing in detail how the amplitude reconstruction (observables measured at a single energy and angle) is related to a truncated partial-wave analysis (observables measured at a single energy and a number of angles).

   ↳ nucl-thnucl-exPRC(2017)·32 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.