Wed·Oct 2, 2019Wednesday·October 2, 2019

1. 01*

   (Anti-)nuclei production and flow in pp, p--Pb and Pb--Pb collisions with ALICE

   Sebastian Hornung (for the ALICE Collaboration)🇩🇪

   High energy pp, p--Pb, and Pb--Pb collisions at the LHC offer a unique opportunity to study the production of light (anti-)nuclei. The study of the production yield of (anti-)nuclei in heavy-ion collisions at LHC energies probes the late stages in the evolution of the hot, dense nuclear matter created in the collision. Measurements performed in smaller collision systems are crucial to understand how the production mechanism evolves going from small to large systems. The results on the determination of the (anti-)nuclei yields will be complemented by the measurement of their azimuthal anisotropic production. This is a powerful tool to gain insight into the production mechanism of light nuclei in relativistic ion collisions: in particular, it will help to distinguish between coalescence and hydrodynamic models. The coalescence parameter and the nuclei-to-proton ratio is studied as a function of the system size, showing a smooth transition from low to high values of the charged-particle multiplicity density. The experimental results can be described with the canonical statistical hadronization model as well as the coalescence approach within uncertainties. The theoretical description of the new results on the measurement of the elliptic and the triangular flow of deuterons and ${}^3$He produced in Pb--Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV requires more sophisticated coalescence and statistical hadronization models.

   nucl-exhep-exPoS(2020)·2 citations
2. 02*

   Unique Access to u-Channel Physics: Exclusive Backward-Angle Omega Meson Electroproduction

   W.B. Li🇺🇸 · G.M. Huber🇨🇦 · H.P. Blok🇳🇱 · D. Gaskell🇺🇸 · T. Horn🇺🇸 · K. Semenov-Tian-Shansky🇷🇺 · B. Pire🇫🇷 · L. Szymanowski🇵🇱 · J.-M. Laget🇺🇸 · K. Aniol🇺🇸 · J. Arrington🇺🇸 · E.J. Beise🇺🇸 and 44 other authors

   Backward-angle meson electroproduction above the resonance region, which was previously ignored, is anticipated to offer unique access to the three quark plus sea component of the nucleon wave function. In this letter, we present the first complete separation of the four electromagnetic structure functions above the resonance region in exclusive omega electroproduction off the proton, e + p -> e' + p + omega, at central Q^2 values of 1.60, 2.45 GeV^2 , at W = 2.21 GeV. The results of our pioneering -u ~ -u min study demonstrate the existence of a unanticipated backward-angle cross section peak and the feasibility of full L/T/LT/TT separations in this never explored kinematic territory. At Q^2 =2.45 GeV^2 , the observed dominance of sigma_T over sigma_L, is qualitatively consistent with the collinear QCD description in the near-backward regime, in which the scattering amplitude factorizes into a hard subprocess amplitude and baryon to meson transition distribution amplitudes (TDAs): universal non-perturbative objects only accessible through backward angle kinematics.

   nucl-exhep-exhep-phnucl-thPRL(2019)·29 citations
3. 03*

   Conversion between the formal and observed parameters in $R$-matrix theory

   M. Katsuma

   The conversion between the formal and observed parameters is obtained from the phase equivalence between the $R$-matrix and Breit-Wigner formula, and it is applied to a study of the low-energy $E$1 $S$-factor of ${}^{12}$C($\alpha$,${\gamma }_0$)${}^{16}$O. As an example, weak interference between 1${}^{-}$ states in ${}^{16}$O is discussed. As well as the ordinary $R$-matrix method, the present method calculates the $S$-matrix and cross sections, independent of the boundary condition. Therefore, the $E$1 $S$-factor at $E_{c.m.}=300$ keV is found to be reduced from the current evaluation.

   ↳ nucl-thnucl-exJPS Conf.Proc.(2020)·2 citations
4. 04*

   Reaction Theory and Advanced CDCC

   A.M. Moro🇪🇸 · J. Casal🇮🇹 · Jin Lei🇺🇸 · M. Gómez-Ramos🇪🇸

   The Continuum-Discretized Coupled-Channels (CDCC) has been successfully employed to describe elastic and breakup of nuclear reactions induced by weakly bound projectiles. In this contribution, we review some other, less widespread applications of the CDCC wavefunction, some of them in combination with other reaction formalisms, which are being currently employed in the analysis of reactions involving three or more fragments in the initial or final state.

   ↳ nucl-thnucl-exJ.Phys.Conf.Ser.(2020)·0 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.