Wed·Mar 13, 2019Wednesday·March 13, 2019

1. 01*

   Probe Chiral Magnetic Effect with Signed Balance Function

   A.H. Tang🇺🇸

   In this paper a pair of observables are proposed as alternative ways, by examining the fluctuation of net momentum-ordering of charged pairs, to study the charge separation induced by the Chiral Magnetic Effect (CME) in relativistic heavy ion collisions. They are, the out-of-plane to in-plane ratio of fluctuation of the difference between signed balance functions measured in pair's rest frame, and the ratio of it to similar measurement made in the laboratory frame. Both observables have been studied with simulations including flow-related backgrounds, and for the first time, backgrounds that are related to resonance's global spin alignment. The two observables have similar positive responses to signal, and opposite, limited responses to identifiable backgrounds arising from resonance flow and spin alignment. Both observables have also been tested with two realistic models, namely, a multi-phase transport (AMPT) model and the anomalous-viscous fluid dynamics (AVFD) model. These two observables, when cross examined, will provide useful insights in the study of CME-induced charge separation.

   nucl-exnucl-thCPC(2020)·51 citations
2. 02*

   Near-Earth Supernova Explosions: Evidence, Implications, and Opportunities

   Brian D. Fields🇺🇸 · John R. Ellis🇬🇧 · Walter R. Binns🇺🇸 · Dieter Breitschwerdt🇩🇪 · Georgia A. de Nolfo🇺🇸 · Roland Diehl🇩🇪 · Vikram V. Dwarkadas🇺🇸 · Adrienne Ertel🇺🇸 · Thomas Faestermann🇩🇪 · Jenny Feige🇩🇪 · Caroline Fitoussi🇫🇷 · Priscilla Frisch🇺🇸 and 27 other authors

   There is now solid experimental evidence of at least one supernova explosion within 100 pc of Earth within the last few million years, from measurements of the short-lived isotope 60Fe in widespread deep-ocean samples, as well as in the lunar regolith and cosmic rays. This is the first established example of a specific dated astrophysical event outside the Solar System having a measurable impact on the Earth, offering new probes of stellar evolution, nuclear astrophysics, the astrophysics of the solar neighborhood, cosmic-ray sources and acceleration, multi-messenger astronomy, and astrobiology. Interdisciplinary connections reach broadly to include heliophysics, geology, and evolutionary biology. Objectives for the future include pinning down the nature and location of the established near-Earth supernova explosions, seeking evidence for others, and searching for other short-lived isotopes such as 26Al and 244Pu. The unique information provided by geological and lunar detections of radioactive 60Fe to assess nearby supernova explosions make now a compelling time for the astronomy community to advocate for supporting multi-disciplinary, cross-cutting research programs.

   ↳ astro-ph.SRastro-ph.EPastro-ph.HEnucl-ex+16 citations
3. 03*

   The Role of Baryon Number Conservation in Measurements of Fluctuations

   Claude A Pruneau🇺🇸

   I discuss the role and impact of net-baryon number conservation in measurements of net proton fluctuations in heavy-ion collisions. I show that the magnitude of the fluctuations is entirely determined by the strength of two particle correlations. At LHC and top RHIC energy, this implies the fluctuations are proportional to the integral of the balance function (BF), $B^{p\bar{p}}$ of protons and anti-protons, while in the context of the RHIC beam energy scan (BES), one must also account for correlations of "stopped" protons. The integral of $B^{p\bar{p}}$ measured in a $4\pi$ detector depends on the relative cross-sections of processes yielding $p\bar{p}$ and those balancing the proton baryon number via the production of other anti-baryons. The accepted integral of $B^{p\bar{p}}$ further depends on the shape and width of the BF relative to the width of the acceptance. The magnitude of the measured second order cumulant of net proton fluctuations thus has much less to do with QCD susceptibilities than with the creation/transport of baryons and anti-baryons in heavy-ion collisions, and most particularly the impact of radial flow on the width of the BF. I thus advocate that net-proton fluctuations should be studied by means of differential BF measurements rather integral correlators.

   ↳ nucl-thhep-exnucl-exPRC(2019)·38 citations
4. 04*

   Potential model for nuclear astrophysical fusion reactions with a square-well potential

   R. Ogura · K. Hagino · C.A. Bertulani🇺🇸

   The potential model for nuclear astrophysical reactions requires a considerably shallow nuclear potential when a square-well potential is employed to fit experimental data. We discuss the origin of this apparently different behavior from that obtained with a smooth Woods-Saxon potential, for which a deep potential is often employed. We argue that due to the sharp change of the potential at the boundary the radius parameter tends to be large in the square-well model, which results in a large absorption radius. The wave function then needs to be suppressed in the absorption region, which can eventually be achieved by using a shallow potential. We thus clarify the reason why the square-well potential has been able to reproduce a large amount of fusion data.

   ↳ nucl-thnucl-exPRC(2019)·5 citations
5. 05*

   Exploring the influence of bulk viscosity of QCD on dilepton tomography

   Gojko Vujanovic🇺🇸 · Jean-François Paquet🇺🇸 · Chun Shen🇺🇸 · Gabriel S. Denicol🇧🇷 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦 · Ulrich Heinz🇺🇸

   The collective behavior of hadrons and of electromagnetic radiation in heavy-ion collisions has been widely used to study the properties of the the Quark-Gluon Plasma (QGP). Indeed this collectivity, as measured by anisotropic flow coefficients, can be used to constrain the transport properties of QGP. The goal of this contribution is to investigate the influence of the specific bulk viscosity ($\zeta /s$) on dilepton production, both at Relativistic Heavy-Ion Collider (RHIC) and Large Hadron Collider (LHC) energies. We explore the sensitivity of dileptons to dynamical features that bulk viscosity induces on the evolution of a strongly-interacting medium, and highlight what makes them a valuable probe in the pursuit to also constrain $\zeta /s$.

   ↳ nucl-thhep-phnucl-exPRC(2020)·40 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.