Wed·Apr 25, 2018Wednesday·April 25, 2018

1. 01*

   Beam energy dependence of rapidity-even dipolar flow in Au+Au collisions

   STAR Collaboration: J. Adam🇺🇸 · L. Adamczyk🇵🇱 · J. R. Adams🇺🇸 · J. K. Adkins🇺🇸 · G. Agakishiev🇷🇺 · M. M. Aggarwal🇮🇳 · Z. Ahammed🇮🇳 · N. N. Ajitanand🇺🇸 · I. Alekseev🇷🇺 · D. M. Anderson🇺🇸 · R. Aoyama🇯🇵 · A. Aparin🇷🇺 and 337 other authors

   New measurements of directed flow for charged hadrons, characterized by the Fourier coefficient \vone, are presented for transverse momenta ${\mathrm{p}}_{\mathrm{T}}$, and centrality intervals in Au+Au collisions recorded by the STAR experiment for the center-of-mass energy range $\sqrt{{\mathrm{s}}_{{}_{\mathrm{NN}}}}=7.7-200$ GeV. The measurements underscore the importance of momentum conservation and the characteristic dependencies on $\sqrt{{\mathrm{s}}_{{}_{\mathrm{NN}}}}$, centrality and ${\mathrm{p}}_{\mathrm{T}}$ are consistent with the expectations of geometric fluctuations generated in the initial stages of the collision, acting in concert with a hydrodynamic-like expansion. The centrality and ${\mathrm{p}}_{\mathrm{T}}$ dependencies of ${\mathrm{v}}_1^{\mathrm{even}}$, as well as an observed similarity between its excitation function and that for ${\mathrm{v}}_3$, could serve as constraints for initial-state models. The ${\mathrm{v}}_1^{\mathrm{even}}$ excitation function could also provide an important supplement to the flow measurements employed for precision extraction of the temperature dependence of the specific shear viscosity.

   nucl-exPLB(2018)·18 citations
2. 02*

   $\varphi$ meson production at forward rapidity in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV

   ALICE Collaboration

   $\varphi$ meson measurements provide insight into strangeness production, which is one of the key observables for the hot medium formed in high-energy heavy-ion collisions. ALICE measured $\varphi$ production through its decay in muon pairs in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV in the intermediate transverse momentum range $2<p_{\mathrm{T}}<5$ GeV/$c$ and in the rapidity interval $2.5<y<4$. The $\varphi$ yield was measured as a function of the transverse momentum and collision centrality. The nuclear modification factor was obtained as a function of the average number of participating nucleons. Results were compared with the ones obtained via the kaon decay channel in the same $p_{\mathrm{T}}$ range at midrapidity. The values of the nuclear modification factor in the two rapidity regions are in agreement within uncertainties.

   nucl-exhep-exEPJC(2018)·9 citations
3. 03*

   Measurement of D${}^0$, D${}^{+}$, D${}^{\ast +}$ and D${}_{\mathrm{s}}^{+}$ production in Pb-Pb collisions at $\sqrt{{\mathbf{s}}_{\mathrm{NN}}}=5.02$ TeV

   ALICE Collaboration

   We report measurements of the production of prompt D${}^0$, D${}^{+}$, D${}^{\ast +}$ and D${}_{\mathrm{s}}^{+}$ mesons in Pb-Pb collisions at the centre-of-mass energy per nucleon-nucleon pair $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV, in the centrality classes 0-10%, 30-50% and 60-80%. The D-meson production yields are measured at mid-rapidity ($|y|<0.5$) as a function of transverse momentum ($p_{\mathrm{T}}$). The $p_{\mathrm{T}}$ intervals covered in central collisions are: $1<p_{\mathrm{T}}<50$ Gev/$c$ for D${}^0$, $2<p_{\mathrm{T}}<50$ GeV/$c$ for D${}^{+}$, $3<p_{\mathrm{T}}<50$ GeV/$c$ for D${}^{\ast +}$, and $4<p_{\mathrm{T}}<16$ GeV/$c$ for D${}_{\mathrm{s}}^{+}$ mesons. The nuclear modification factors ($R_{\mathrm{AA}}$) for non-strange D mesons (D${}^0$, D${}^{+}$, D${}^{\ast +}$) show minimum values of about 0.2 for $p_{\mathrm{T}}$ = 6-10 GeV/$c$ in the most central collisions and are compatible within uncertainties with those measured at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV. For D${}_{\mathrm{s}}^{+}$ mesons, the values of $R_{\mathrm{AA}}$ are larger than those of non-strange D mesons, but compatible within uncertainties. In central collisions the average $R_{\mathrm{AA}}$ of non-strange D mesons is compatible with that of charged particles for $p_{\mathrm{T}}>8$ GeV/$c$, while it is larger at lower $p_{\mathrm{T}}$. The nuclear modification factors for strange and non-strange D mesons are also compared to theoretical models with different implementations of in-medium energy loss.

   nucl-exhep-exJHEP(2018)·249 citations
4. 04*

   Evaluation of low-$Q^2$ fits to $ep$ and $ed$ elastic scattering data

   Timothy B. Hayward🇺🇸 · Keith A. Griffioen🇺🇸

   We examined several low-$Q^2$ elastic $ep$ and $ed$ scattering data sets using various models to extract the proton and deuteron rms radii and developed a comprehensive algorithm for estimating the systematic bias of each extracted radius. In each case, we chose the model and upper bound for $Q^2$ that minimized the combination of statistical uncertainty and bias. We attribute the discrepancy between small ($\approx 0.84$~fm) and large ($\approx 0.88$~fm) proton radius extractions to the absence of data that can accurately isolate the linear and quadratic contributions to the form factor at low-$Q^2$. In light of this ambiguity, we estimated the asymmetric model-dependence of each extracted radius by studying the distribution of many possible fits. The resulting radii are 0.842(4)~fm for the proton and 2.092(19)~fm for the deuteron. These values are consistent with those determined from muonic hydrogen measurements within 0.3$\sigma$ for the proton and 1.8$\sigma$ for the deuteron.

   nucl-exhep-phNPA(2020)·22 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.