Thu·Sep 28, 2017Thursday·September 28, 2017

1. 01*

   Observation of correlated azimuthal anisotropy Fourier harmonics in pp and pPb collisions at the LHC

   CMS Collaboration

   The azimuthal anisotropy Fourier coefficients ($v_n$) in 8.16 TeV pPb data are extracted via long-range two-particle correlations as a function of event multiplicity and compared to corresponding results in pp and PbPb collisions. Using a four-particle cumulant technique, $v_n$ correlations are measured for the first time in pp and pPb collisions. The $v_2$ and $v_4$ coefficients are found to be positively correlated in all collision systems. For high multiplicity pPb collisions an anticorrelation of $v_2$ and $v_3$ is observed, with a similar correlation strength as in PbPb data at the same multiplicity. The new correlation results strengthen the case for a common origin of the collectivity seen in pPb and PbPb collisions in the measured multiplicity range.

   nucl-exhep-exPRL(2018)·134 citations
2. 02*

   High Precision Measurement of the ${}^{19}$Ne Half-life using real-time digital acquisition

   C. Fontbonne🇫🇷 · P. Ujić🇷🇸 · F. de Oliveira Santos🇫🇷 · X. Fléchard🇫🇷 · F. Rotaru🇷🇴 · N. L. Achouri🇫🇷 · V. Girard Alcindor🇫🇷 · B. Bastin🇫🇷 · F. Boulay🇫🇷 · J. B. Briand🇫🇷 · A. M. Sánchez-Benítez🇫🇷 · H. Bouzomita🇫🇷 and 25 other authors

   The half-life of ${}^{19}$Ne has been measured using a real-time digital multiparametric acquisition system providing an accurate time-stamp and relevant information on the detectors signals for each decay event. An exhaustive offline analysis of the data gave unique access to experimental effects potentially biasing the measurement. After establishing the influence factors impacting the measurement such as after-pulses, pile-up, gain and base line fluctuations, their effects were accurately estimated and the event selection optimized. The resulting half-life, $17.2569\pm 0.0019_{(stat)}\pm 0.0009_{(syst)}$~s, is the most precise up to now for ${}^{19}$Ne. It is found in agreement with two recent precise measurements and not consistent with the most recent one [L.J. Broussard {\it et al.}, Phys. Rev. Lett. {\bf112}, 212301 (2014)] by 3.0 standard deviations. The full potential of the technique for nuclei with half-lives of a few seconds is discussed.

   nucl-exphysics.ins-detPRC(2017)·8 citations
3. 03*

   New results on jets and heavy flavor in heavy-ion collisions with ALICE

   Salvatore Aiola (for the ALICE Collaboration)🇺🇸

   The large statistics accumulated during the LHC Run-1 and Run-2 have provided the unique opportunity to study the properties of the Quark-Gluon Plasma using rare hard probes. The ALICE Collaboration has presented new results on the jet shape observables in p--Pb and Pb--Pb collision. Using data from Run-2, the elliptic flow of open and hidden charm mesons have been measured with much better precision, confirming that charm quarks participate in the collective dynamic expansion with the medium. In p--Pb collisions the absence of jet quenching correlated with high event activity has been confirmed by a self-normalized semi-inclusive hadron+jet measurement.

   nucl-ex2 citations
4. 04*

   Validating neural-network refinements of nuclear mass models

   R. Utama · J. Piekarewicz🇺🇸

   Nuclear astrophysics centers on the role of nuclear physics in the cosmos. In particular, nuclear masses at the limits of stability are critical in the development of stellar structure and the origin of the elements. In this contribution we test and validate the predictions of recently refined nuclear mass models against the newly published AME2016 compilation. The basic paradigm underlining the recently refined nuclear mass models is based on existing state-of-the-art models that are subsequently refined through the training of an artificial neural network. We observe a significant improvement in the Bayesian Neural Network (BNN) predictions relative to the corresponding "bare" models when compared to the nearly 50 new masses reported in the AME2016 compilation. Further, AME2016 estimates for the handful of impactful isotopes in the determination of r-process abundances are found to be in fairly good agreement with our theoretical predictions. Indeed, the BNN-improved Duflo-Zuker model predicts a root-mean-square deviation relative to experiment of about 400 keV. Given the excellent performance of the BNN refinement in confronting the recently published AME2016 compilation, we are confident of its critical role in our quest for mass models of the highest quality. Moreover, as uncertainty quantification is at the core of the BNN approach, the improved mass models are in a unique position to identify those nuclei that will have the strongest impact in resolving some of the outstanding questions in nuclear astrophysics.

   ↳ nucl-thnucl-exPRC(2018)·57 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.