Wed·Apr 12, 2017Wednesday·April 12, 2017

1. 01*

   Anisotropic flow of inclusive and identified particles in Pb--Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV

   R. A. Bertens (for the ALICE collaboration)🇨🇭

   Anisotropic flow measurements constrain the shear $(\eta /s)$ and bulk ($\zeta /s$) viscosity of the quark-gluon plasma created in heavy-ion collisions, as well as give insight into the initial state of such collisions and hadronization mechanisms. In these proceedings, elliptic ($v_2$) and higher harmonic ($v_3,v_4$) flow coefficients of ${\pi }^{\pm }$, $K^{\pm }$, p$(\overline{\mathrm{p}})$ and the $\varphi$-meson,measured in Pb--Pb collisions at the highest-ever center-of-mass energy of $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV, are presented.

   nucl-exNPA(2017)·6 citations
2. 02*

   Measurement of the Shared Momentum Fraction $z_g$ using Jet Reconstruction in p+p and Au+Au Collisions with STAR

   Kolja Kauder (for the STAR Collaboration)🇺🇸

   One key difference in current energy loss models lies in the treatment of the Altarelli-Parisi, AP, splitting functions. It has been shown that the shared momentum fraction, henceforth called Jet Splitting Function $z_g$ as determined by the SoftDrop grooming process can be made a Sudakov-safe measurement of the symmetrized AP functions in p+p collisions. The STAR collaboration presents the first z_g measurements at $\sqrt{s_{NN}}=200$ GeV in p+p and Au+Au collisions, where in Au+Au we use the specific di-jet selection introduced in our previous momentum imbalance measurement. For a jet resolution parameter of $R=0.4$, these di-jet pairs were found to be significantly imbalanced with respect to p+p, yet regained balance when all soft constituents were included. We find that within uncertainties there are no signs of a modified Jet Splitting Function on trigger or recoil sides of this di-jet selection.

   nucl-exNPA(2017)·22 citations
3. 03*

   Precise measurement of alpha_K and alpha_T for the 109.3-keV M4 transition in 125Te: Test of internal-conversion theory

   N. Nica🇺🇸 · J.C. Hardy🇺🇸 · V.E. Iacob🇺🇸 · T.A. Werke · C.M. Folden III · K. Ofodile · M.B. Trzhaskovskaya

   We have measured the K-shell and total internal conversion coefficients (ICCs), alpha_K and alpha_T, for the 109.3-keV M4 transition in 125Te to be 185.0(40) and 350.0(38), respectively. Previously this transition's ICCs were considered anomalous, with alpha values lying below calculated values. When compared with Dirac-Fock calculations, our new results show good agreement. The alpha_K result agrees well with the version of the theory that takes account of the K-shell atomic vacancy and disagrees with the one that does not. This is consistent with our conclusion drawn from a series of high multipolarity transitions.

   nucl-exnucl-thPRC(2017)·4 citations
4. 04*

   Measurement of 1323 and 1487 keV resonances in 15N({\alpha}, {\gamma})19F with the recoil separator ERNA

   A. Di Leva (1 and 2)🇮🇹 · G. Imbriani (1 and 2)🇮🇹 · R. Buompane (3 and 2)🇮🇹 · L. Gialanella (3 and 2)🇮🇹 · A. Best (1 and 2)🇮🇹 · S. Cristallo (4 and 5)🇮🇹 · M. De Cesare (6 and 3 and 2) · A. D'Onofrio (3 and 2)🇮🇹 · J. G. Duarte (3 and 2)🇪🇸 · L. R. Gasques (7 and 3 and 2) · L. Morales-Gallegos (8 and 2) · A. Pezzella (9 and 2) and 7 other authors

   The origin of fluorine is a widely debated issue. Nevertheless, the ^{15}N({\alpha},{\gamma})^{19}F reaction is a common feature among the various production channels so far proposed. Its reaction rate at relevant temperatures is determined by a number of narrow resonances together with the DC component and the tails of the two broad resonances at E_{c.m.} = 1323 and 1487 keV. Measurement through the direct detection of the 19F recoil ions with the European Recoil separator for Nuclear Astrophysics (ERNA) were performed. The reaction was initiated by a 15N beam impinging onto a 4He windowless gas target. The observed yield of the resonances at Ec.m. = 1323 and 1487 keV is used to determine their widths in the {\alpha} and {\gamma} channels. We show that a direct measurement of the cross section of the ^{15}N({\alpha},{\gamma})^{19}F reaction can be successfully obtained with the Recoil Separator ERNA, and the widths {\Gamma}_{\gamma} and {\Gamma}_{\alpha} of the two broad resonances have been determined. While a fair agreement is found with earlier determination of the widths of the 1487 keV resonance, a significant difference is found for the 1323 keV resonance {\Gamma}_{\alpha} . The revision of the widths of the two more relevant broad resonances in the 15N({\alpha},{\gamma})19F reaction presented in this work is the first step toward a more firm determination of the reaction rate. At present, the residual uncertainty at the temperatures of the ^{19}F stellar nucleosynthesis is dominated by the uncertainties affecting the Direct Capture component and the 364 keV narrow resonance, both so far investigated only through indirect experiments.

   nucl-exPRC(2017)·15 citations
5. 05*

   Constraint on the Ground-state Mass of 21Al and Three-Nucleon Forces

   X.Z. Teng · C.E. Teh · J. Lee · X.X. Xu · C.J. Lin · L.J. Sun · J.S. Wang · D.Q. Fang · S. Leblond · Z.H. Li · J. Li · N.R. Ma and 15 other authors

   Fragmentation cross section of ${}^{28}$Si + ${}^9$Be reaction at 75.8 MeV/u was analyzed for studying the decay mode of single-proton emission in ${}^{21}$Al (the proton-rich nucleus with neutron closed-shell of $N=8$ and $T_z=-5/2$). With the comparison between the measured fragmentation cross section and the theoretical cross section produced by EPAX3.1a for the observed nuclei (i.e. ${}^{20}$Mg, ${}^{21}$Al and ${}^{22}$Si), the expected yield for a particle stable ${}^{21}$Al was estimated. With the exponential decay law, an upper limit of half-life of $13$ ns was determined. Using the single-proton penetration model, the upper limit of single-proton separation energy of $-105$ keV was deduced. This deduced mass limit agrees with the microscopic calculation based on nucleon-nucleon (NN) + three-nucleon (3N) forces in $sd{f}_{7/2}{p}_{3/2}$ valence space, which indicates the importance of 3N forces in ${}^{21}$Al.

   nucl-ex0 citations
6. 06*

   Effects of enhanced bulk viscosity near the QCD critical point

   Akihiko Monnai🇫🇷 · Swagato Mukherjee🇺🇸 · Yi Yin🇺🇸

   Search for the conjectured QCD critical point is one of the major scientific goals for the Beam Energy Scan program at RHIC. The growth of the correlation length is a universal feature for systems near criticality, and bulk viscosity exhibits the strongest dependence on the correlation length. We investigate its effects using a relativistic hydrodynamic model to find that rapidity distributions of charged particles and net baryon number are visibly modified if the fireball passes through the vicinity of the QCD critical point on the phase diagram. We also discuss how critical modification of dilepton emission rate may leave imprints on invariant mass spectra.

   ↳ nucl-thhep-phnucl-exNPA(2017)·6 citations
7. 07*

   Elastic Scattering Phenomenology

   R.S. Mackintosh

   We argue that, in many situations, fits to elastic scattering data that were historically, and frequently still are, considered `good', are not justifiably so describable. Information about the dynamics of nucleon-nucleus and nucleus-nucleus scattering is lost when elastic scattering phenomenology is insufficiently ambitious. It is argued that in many situations, an alternative approach is appropriate for the phenomenology of nuclear elastic scattering of nucleons and other light nuclei. The approach affords an appropriate means of evaluating folding models, one that fully exploits available empirical data. It is particularly applicable for nucleons and other light ions.

   ↳ nucl-thnucl-exEPJA(2017)·4 citations
8. 08*

   Bayesian truncation errors in chiral effective field theory: nucleon-nucleon observables

   J.A. Melendez🇺🇸 · S. Wesolowski🇺🇸 · R.J. Furnstahl🇺🇸

   Chiral effective field theory (EFT) predictions are necessarily truncated at some order in the EFT expansion, which induces an error that must be quantified for robust statistical comparisons to experiment. In previous work, a Bayesian model for truncation errors of perturbative expansions was adapted to EFTs. The model yields posterior probability distribution functions (pdfs) for these errors based on expectations of naturalness encoded in Bayesian priors and the observed order-by-order convergence pattern of the EFT. A first application was made to chiral EFT for neutron-proton scattering using the semi-local potentials of Epelbaum, Krebs, and Meißner (EKM). Here we extend this application to consider a larger set of regulator parameters, energies, and observables as a general example of a statistical approach to truncation errors. The Bayesian approach allows for statistical validations of the assumptions and enables the calculation of posterior pdfs for the EFT breakdown scale. The statistical model is validated for EKM potentials whose convergence behavior is not distorted by regulator artifacts. For these cases, the posterior for the breakdown scale is consistent with EKM assumptions.

   ↳ nucl-thhep-phnucl-exphysics.data-anPRC(2017)·188 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.