Fri·Oct 18, 2019Friday·October 18, 2019

1. 01*

   Production of charged pions, kaons and (anti-)protons in Pb-Pb and inelastic pp collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV

   ALICE Collaboration

   Mid-rapidity production of ${\pi }^{\pm }$, ${\mathrm{K}}^{\pm }$ and ($\bar{\mathrm{p}}$)p measured by the ALICE experiment at the LHC, in Pb-Pb and inelastic pp collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV, is presented. The invariant yields are measured over a wide transverse momentum ($p_{\mathrm{T}}$) range from hundreds of MeV/$c$ up to 20 GeV/$c$. The results in Pb-Pb collisions are presented as a function of the collision centrality, in the range 0$-$90%. The comparison of the $p_{\mathrm{T}}$-integrated particle ratios, i.e. proton-to-pion (p/$\pi$) and kaon-to-pion (K/$\pi$) ratios, with similar measurements in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV show no significant energy dependence. Blast-wave fits of the $p_{\mathrm{T}}$ spectra indicate that in the most central collisions radial flow is slightly larger at 5.02 TeV with respect to 2.76 TeV. Particle ratios (p/$\pi$, K/$\pi$) as a function of $p_{\mathrm{T}}$ show pronounced maxima at $p_{\mathrm{T}}$ $\approx$ 3 GeV/$c$ in central Pb-Pb collisions. At high $p_{\mathrm{T}}$, particle ratios at 5.02 TeV are similar to those measured in pp collisions at the same energy and in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV. Using the pp reference spectra measured at the same collision energy of 5.02 TeV, the nuclear modification factors for the different particle species are derived. Within uncertainties, the nuclear modification factor is particle species independent for high $p_{\mathrm{T}}$ and compatible with measurements at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV. The results are compared to state-of-the-art model calculations, which are found to describe the observed trends satisfactorily.

   nucl-exhep-exPRC(2020)·425 citations
2. 02*

   Inverse-kinematics proton scattering from ${}^{42,44}$S, ${}^{41,43}$P and the collapse of the $N=28$ major shell closure

   L. A. Riley🇺🇸 · D. Bazin🇺🇸 · J. Belarge · P. C. Bender🇨🇦 · B. A. Brown🇺🇸 · P. D. Cottle🇺🇸 · B. Elman · A. Gade🇺🇸 · S. D. Gregory🇺🇸 · E. B. Haldeman🇺🇸 · K. W. Kemper🇺🇸 · B. R. Klybor and 12 other authors

   Excited states of the neutron-rich isotopes ${}^{42,44}$S and ${}^{41,43}$P have been studied via inverse-kinematics proton scattering from a liquid hydrogen target, using the GRETINA $\gamma$-ray tracking array to extract inelastic scattering cross sections. Deformation lengths of the $2_1^{+}$ excitations in ${}^{42,44}$S have been determined and, when combined with deformation lengths determined with electromagnetic probes, yield the ratio of neutron-to-proton matrix elements $M_n/M_p$ for the $2_1^{+}$ excitations in these nuclei. The present results for ${}^{41,43}$P$(p,p^{\prime })$ are used to compare two shell model interactions, SDPF-U and SDPF-MU. As in a recent study of ${}^{42}$Si, the present results on ${}^{41,43}$P favor the SDPF-MU interaction.

   nucl-exPRC(2019)·17 citations
3. 03*

   Centrality selection effect on higher-order cumulants of net-proton multiplicity distributions in relativistic heavy-ion collisions

   Arghya Chatterjee🇨🇳 · Yu Zhang🇨🇳 · Jingdong Zeng🇨🇳 · Nihar Ranjan Sahoo🇨🇳 · Xiaofeng Luo🇨🇳

   We studied the centrality selection effect on cumulants (up to fourth order) and the cumulants ratios of net-proton multiplicity distributions in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 7.7, 19.6 and 200 GeV from UrQMD model. The net-proton cumulants are calculated with collision centralities by using charged particle multiplicity from different pesudorapidity ($\eta$) region. By comparing the results from various collision centralities, we found that the autocorrelation effects are not significant in the results with collision centralities "refmult-3" and "refmult-2", which are using mid-rapidity charged particles but excluding (anti-)protons and analysis region, respectively. Furthermore, due to the contributions of spectator protons, we observed poor centrality resolution when using charged particles at forward $\eta$ region at low energies. This work can serve as a baseline for centrality selection of future fluctuations analysis in relativistic heavy-ion collisions.

   nucl-exhep-phnucl-thPRC(2020)·28 citations
4. 04*

   The Central Drift Chamber for GlueX

   N. S. Jarvis🇺🇸 · C. A. Meyer🇺🇸 · B. Zihlmann🇺🇸 · M. Staib🇺🇸 · A. Austregesilo🇺🇸 · F. Barbosa🇺🇸 · C. Dickover🇺🇸 · V. Razmyslovich🇺🇸 · S. Taylor🇺🇸 · Y. Van Haarlem🇧🇪 · G. Visser🇺🇸 · T. Whitlatch🇺🇸

   The Central Drift Chamber is a straw-tube wire chamber of cylindrical structure located surrounding the target inside the bore of the GlueX spectrometer solenoid. Its purpose is to detect and track charged particles with momenta as low as 0.25 GeV/c as well as to identify low-momentum protons via energy loss. The construction of the detector is described and its operation and calibration are discussed in detail. The design goal of 150 microns in position resolution has been reached.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2020)·25 citations
5. 05*

   Towards grounding nuclear physics in QCD

   Christian Drischler🇺🇸 · Wick Haxton🇺🇸 · Kenneth McElvain🇺🇸 · Emanuele Mereghetti🇺🇸 · Amy Nicholson🇺🇸 · Pavlos Vranas🇺🇸 · André Walker-Loud🇺🇸

   Exascale computing could soon enable a predictive theory of nuclear structure and reactions rooted in the Standard Model, with quantifiable and systematically improvable uncertainties. Such a predictive theory will help exploit experiments that use nucleons and nuclei as laboratories for testing the Standard Model and its limitations. Examples include direct dark matter detection, neutrinoless double beta decay, and searches for permanent electric dipole moments of the neutron and atoms. It will also help connect QCD to the properties of cold neutron stars and hot supernova cores. We discuss how a quantitative bridge between QCD and the properties of nuclei and nuclear matter will require a synthesis of lattice QCD (especially as applied to two- and three-nucleon interactions), effective field theory, and ab initio methods for solving the nuclear many-body problem. While there are significant challenges that must be addressed in developing this triad of theoretical tools, the rapid advance of computing is accelerating progress. In particular, we focus this review on the anticipated advances from lattice QCD and how these advances will impact few-body effective theories of nuclear physics by providing critical input, such as constraints on unknown low-energy constants of the effective (field) theories. We also review particular challenges that must be overcome for the successful application of lattice QCD for low-energy nuclear physics. We describe progress in developing few-body effective (field) theories of nuclear physics, with an emphasis on HOBET, a non-relativistic effective theory of nuclear physics, which is less common in the literature. We use the examples of neutrinoless double beta decay and the nuclear-matter equation of state to illustrate how the coupling of lattice QCD to effective theory might impact our understanding of symmetries and exotic astrophysical environments.

   ↳ nucl-thhep-exhep-lathep-ph+1PPNP(2021)·121 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.