Fri·Jul 23, 2021Friday·July 23, 2021

1. 01*

   Using coherent dipion photoproduction to image gold nuclei

   Spencer R. Klein (for the STAR Collaboration)🇺🇸

   Vector meson photoproduction offers the opportunity to image target nuclei. The two-dimensional Fourier transform $d{\sigma }_{\mathrm{coherent}}/dt$ of coherent vector meson photoproduction gives the two-dimensional distribution of interaction sites in the target. Since vector meson photoproduction occurs, at lowest order, via two-gluon exchange, this is sensitive to gluon shadowing. We present an analysis of ${\pi }^{+}{\pi }^{-}$ photoproduction using data from the STAR detector and a study of $d{\sigma }_{\mathrm{coherent}}/dt$, with an emphasis on probing the nuclear shape and its systematic uncertainties.

   nucl-exhep-exSciPost Phys.Proc.(2022)·8 citations
2. 02*

   Anisotropic flow of identified hadrons in Xe-Xe collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.44TeV

   ALICE Collaboration

   Measurements of elliptic ($v_2$) and triangular ($v_3$) flow coefficients of ${\pi }^{\pm }$, K${}^{\pm }$, p+$\overline{\mathrm{p}}$, K${}_{\mathrm{S}}^0$, and $\Lambda +\overline{\Lambda }$ obtained with the scalar product method in Xe-Xe collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.44 TeV are presented. The results are obtained in the rapidity range $\left|y\right|<0.5$ and reported as a function of transverse momentum, $p_{\mathrm{T}}$, for several collision centrality classes. The flow coefficients exhibit a particle mass dependence for $p_{\mathrm{T}}<3$ GeV/$c$, while a grouping according to particle type (i.e., meson and baryon) is found at intermediate transverse momenta (3< $p_{\mathrm{T}}$ <8 GeV/$c$). The magnitude of the baryon $v_2$ is larger than that of mesons up to $p_{\mathrm{T}}$ = 6 GeV/$c$. The centrality dependence of the shape evolution of the $p_{\mathrm{T}}$-differential $v_2$ is studied for the various hadron species. The $v_2$ coefficients of ${\pi }^{\pm }$, K${}^{\pm }$, and p+$\overline{\mathrm{p}}$ are reproduced by MUSIC hydrodynamic calculations coupled to a hadronic cascade model (UrQMD) for $p_{\mathrm{T}}<1$ GeV/$c$. A comparison with $v_{\mathrm{n}}$ measurements in the corresponding centrality intervals in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV yields an enhanced $v_2$ in central collisions and diminished value in semicentral collisions.

   nucl-exhep-exJHEP(2021)·26 citations
3. 03*

   Hypertriton production in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV

   ALICE Collaboration

   The study of nuclei and antinuclei production has proven to be a powerful tool to investigate the formation mechanism of loosely bound states in high-energy hadronic collisions. The first measurement of the production of ${}_{\mathrm{\Lambda }}^3\mathrm{H}$ in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV is presented in this Letter. Its production yield measured in the rapidity interval $-1<y<0$ for the 40% highest multiplicity p-Pb collisions is $\mathrm{d}N/\mathrm{d}y=[6.3\pm 1.8(stat.)\pm 1.2(syst.)]\times 10^{-7}$. The measurement is compared with the expectations of statistical hadronisation and coalescence models, which describe the nucleosynthesis in hadronic collisions. These two models predict very different yields of the hypertriton in charged particle multiplicity environments relevant to small collision systems such as p-Pb and therefore the measurement of $\mathrm{d}N/\mathrm{d}y$ is crucial to distinguish between them. The precision of this measurement leads to the exclusion with a significance larger than 6.9$\sigma$ of some configurations of the statistical hadronization model, thus constraining the theory behind the production of loosely bound states at hadron colliders.

   nucl-exhep-exPRL(2022)·55 citations
4. 04*

   Light cluster production in central symmetric heavy-ion reactions from Fermi to GeV energies

   Rémi Bougault · Bernard Borderie · Abdelouahad Chbihi · Quentin Fable · John David Frankland · Emmanuelle Galichet · Tom Genard · Diégo Gruyer · Maxime Henri · Marco La Commara · Nicolas Le Neindre · Ivano Lombardo and 5 other authors

   Correlations and clustering are of great importance in the study of the Nuclear Equation of State. Information on these items/aspects can be obtained using Heavy-Ion reactions which are described by dynamical theories. We propose a dataset that will be useful for improving the description of light cluster production in transport model approaches. The dataset combines published and new data and is presented in a form that allows direct comparison of the experiment with theoretical predictions. The dataset is ranging in bombarding energy from 32 to 1930 A MeV. In constructing this dataset we put in evidence the existence of a change in the light cluster production mechanism that corresponds to a peak in deuteron production.

   nucl-exSymmetry(2021)·4 citations
5. 05*

   Study of very forward energy and its correlation with particle production at midrapidity in pp and p-Pb collisions at the LHC

   ALICE Collaboration

   The energy deposited at very forward rapidities (very forward energy) is a powerful tool for characterising proton fragmentation in pp and p$-$Pb collisions. The correlation of very forward energy with particle production at midrapidity provides direct insights into the initial stages and the subsequent evolution of the collision. Furthermore, the correlation with the production of particles with large transverse momenta at midrapidity provides information complementary to the measurements of the underlying event, which are usually interpreted in the framework of models implementing centrality-dependent multiple parton interactions. Results about very forward energy, measured by the ALICE zero degree calorimeters (ZDCs), and its dependence on the activity measured at midrapidity in pp collisions at $\sqrt{s}=13$ TeV and in p$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=8.16$ TeV are discussed. The measurements performed in pp collisions are compared with the expectations of three hadronic interaction event generators: PYTHIA 6 (Perugia 2011 tune), PYTHIA 8 (Monash tune), and EPOS LHC. These results provide new constraints on the validity of models in describing the beam remnants at very forward rapidities, where perturbative QCD cannot be used.

   nucl-exhep-exJHEP(2022)·10 citations
6. 06*

   Impact of clustering on the ${}^8$Li $\beta$ decay and recoil form factors

   G. H. Sargsyan🇺🇸 · K. D. Launey🇺🇸 · M. T. Burkey · A. T. Gallant · N. D. Scielzo · G. Savard🇺🇸 · A. Mercenne🇺🇸 · T. Dytrych · D. Langr🇨🇿 · L. Varriano🇺🇸 · B. Longfellow🇺🇸 · T. Y. Hirsh · J. P. Draayer🇺🇸

   We place unprecedented constraints on recoil corrections in the $\beta$ decay of ${}^8$Li, by identifying a strong correlation between them and the ${}^8$Li ground state quadrupole moment in large-scale ab initio calculations. The results are essential for improving the sensitivity of high-precision experiments that probe the weak interaction theory and test physics beyond the Standard Model (BSM). In addition, our calculations predict a $2^{+}$ state of the $\alpha +\alpha$ system that is energetically accessible to $\beta$ decay but has not been observed in the experimental ${}^8$Be energy spectrum, and has an important effect on the recoil corrections and $\beta$ decay for the $A=8$ systems. This state and an associated $0^{+}$ state are notoriously difficult to model due to their cluster structure and collective correlations, but become feasible for calculations in the ab initio symmetry-adapted no-core shell-model framework.

   ↳ nucl-thnucl-exPRL(2022)·44 citations
7. 07*

   A formalism to assess the accuracy of nuclear-structure weak interaction effects in precision $\beta$-decay studies

   Ayala Glick-Magid🇮🇱 · Doron Gazit🇮🇱

   Multiple high precision $\beta$-decay measurements are being carried out these days on various nuclei, in search of beyond the Standard Model signatures. These measurements necessitate accurate standard model theoretical predictions to be compared with. Motivated by the experimental surge, we present a formalism for such a calculation of $\beta$-decay observables, with controlled accuracy, based on a perturbative analysis of the theoretical observables related to the phenomena, including high order nuclear recoil and shape corrections. The accuracy of the corrections is analyzed by identifying a hierarchy of small parameters, related to the low momentum transfer characterizing $\beta$-decays. Furthermore, we show that the sub-percent uncertainties, targeted by on-going and planned experiments, entail an accuracy of the order of 10\% for the solution of the nuclear many body problem, which is well within the reach of modern nuclear theory for light to medium mass nuclei.

   ↳ nucl-thhep-phnucl-exJ.Phys.G(2022)·19 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.