Wed·Aug 19, 2020Wednesday·August 19, 2020

1. 01*

   Single-particle structure in neutron-rich Sr isotopes approaching the N = 60 shape transition

   S. Cruz🇨🇦 · K. Wimmer🇯🇵 · S.S. Bhattacharjee🇨🇦 · P.C. Bender🇨🇦 · G. Hackman🇨🇦 · R. Krücken🇨🇦 · F. Ames🇨🇦 · C. Andreoiu🇨🇦 · R.A.E. Austin🇨🇦 · C.S. Bancroft🇺🇸 · R. Braid🇺🇸 · T. Bruhn🇨🇦 and 24 other authors

   Background: Neutron-rich nuclei around neutron number N = 60 show a dramatic shape transition from spherical ground states to prolate deformation in 98Sr and heavier nuclei. Purpose: The purpose of this study is to investigate the single-particle structure approaching the shape transitional region. Method: The level structures of neutron-rich 93,94,95Sr were studied via the d(94,95,96Sr,t) one-neutron stripping reactions at TRIUMF using a beam energy of 5.5 AMeV. {\gamma}-rays emitted from excited states and recoiling charged particles were detected by using the TIGRESS and SHARC arrays, respectively. States were identified by gating on the excitation energy and, if possible, the coincident {\gamma} radiation. Results: Triton angular distributions for the reactions populating states in ejectile nuclei 93,94,95Sr were compared with distorted wave Born approximation calculations to assign and revise spin and parity quantum numbers and extract spectroscopic factors. The results were compared with shell model calculations and the reverse (d,p) reactions and good agreement was obtained. Conclusions: The results for the d(94Sr,t)93Sr and d(95Sr,t)94Sr reactions are in good agreement with shell model calculations. A two level mixing analysis for the 0+ states in 94Sr suggest strong mixing of two shapes. For the d(96Sr,t)95Sr reaction the agreement with the shell model is less good. The configuration of the ground state of 96Sr is already more complex than predicted, and therefore indications for the shape transition can already be observed before N = 60.

   nucl-exPRC(2020)·11 citations
2. 02*

   Multiplicity and pseudorapidity density distributions of charged particles produced in pp, pA and AA collisions at RHIC \& LHC energies

   Sumit Basu🇺🇸 · Sanchari Thakur🇮🇳 · Tapan K. Nayak🇮🇳 · Claude A. Pruneau🇺🇸

   Multiplicity and pseudorapidity ($\eta$) density ($d{N}_{\mathrm{ch}}/d\eta$) distributions of charged hadrons provide key information towards understanding the particle production mechanisms and initial conditions of high-energy heavy-ion collisions. However, detector constraints limit the $\eta$-range across which charged particle measurements can be carried out. Extrapolating the measured distributions to large $\eta$-range by parameterizing measured distributions and by using calculations from event generators, we characterize the production of charged particles over the full kinematic range. In the present study, we use three different ans$\ddot{\mathrm{a}}$tze to obtain quantitative descriptions of the shape of pseudorapidity distributions of charged hadrons produced in pp, p-A, and A-A collisions for beam energies ($\sqrt{s_{\mathrm{NN}}}$) ranging from a few GeV to a few TeV corresponding to RHIC and LHC energies. We study the limiting fragmentation behavior in these collisions and report evidence for participant-scaling violations in high-energy collisions at the TeV scale. We additionally examine measured pseudorapidity distributions to constrain models describing initial conditions of particle production. We predict the centrality dependence of charged particle multiplicity distributions at FAIR and NICA energies and give an estimation of charged particle multiplicity at $\eta =0$ for the proposed HE-LHC and FCC energies.

   nucl-exhep-exhep-phJ.Phys.G(2020)·19 citations
3. 03*

   Electroweak-boson production in p-Pb and Pb-Pb collisions at the LHC with ALICE

   Guillaume Taillepied (for the ALICE Collaboration)🇫🇷

   Electroweak bosons are sensitive probes of the initial state of heavy-ion collisions, of which a precise knowledge is required in order to disentangle initial state effects from phenomena induced by the presence of the quark--gluon plasma (QGP). The production rate of the Z and W${}^{\pm }$ bosons is especially sensitive to the nuclear modification of the Parton Distribution Functions (PDF), and the muonic decays (Z $\to {\mu }^{+}{\mu }^{-}$ and W${}^{\pm }\to {\mu }^{\pm }\nu$) offer medium-blind processes carrying this information to the detector where it can be directly collected. In this contribution, new measurements of electroweak bosons in p--Pb collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}$ = 8.16 TeV and Pb--Pb collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}$ = 5.02 TeV measured by the ALICE Collaboration are reported. The data are collected at forward rapidity with the ALICE muon spectrometer and are compared to theoretical predictions with and without including nuclear modifications.

   nucl-exPoS(2020)·2 citations
4. 04*

   Multiple chiral bands in ${}^{137}$Nd

   C. M. Petrache🇫🇷 · B. F. Lv🇨🇳 · Q. B. Chen🇩🇪 · J. Meng🇨🇳 · A. Astier🇫🇷 · E. Dupont🇫🇷 · K. K. Zheng🇫🇷 · P. T. Greenlees🇫🇮 · H. Badran🇫🇮 · T. Calverley🇫🇮 · D. M. Cox🇫🇮 · T. Grahn🇫🇮 and 26 other authors

   Two new bands have been identified in ${}^{137}$Nd from a high-statistics JUROGAM II gamma-ray spectroscopy experiment. Constrained density functional theory and particle rotor model calculations are used to assign configurations and investigate the band properties, which are well described and understood. It is demonstrated that these two new bands can be interpreted as chiral partners of previously known three-quasiparticle positive- and negative-parity bands. The newly observed chiral doublet bands in ${}^{137}$Nd represent an important support to the existence of multiple chiral bands in nuclei. The present results constitute the missing stone in the series of Nd nuclei showing multiple chiral bands, which becomes the most extended sequence of nuclei presenting multiple chiral bands in the Segré chart.

   nucl-exnucl-thEPJA(2020)·18 citations
5. 05*

   Probing the Deuteron at Very Large Internal Momenta

   Carlos Yero (for the Hall C Collaboration)

   ${}^2\mathrm{H}(e,e^{\prime }p)n$ cross sections have been measured at 4-momentum transfers of $Q^2=4.5\pm 0.5$ (GeV/c)${}^2$ over a range of neutron recoil momenta, $p_{\mathrm{r}}$, reaching up to $\sim 1.0$ GeV/c. The data were obtained at fixed neutron recoil angles ${\theta }_{nq}=35^{\circ }$, $45^{\circ }$ and $75^{\circ }$ with respect to the 3-momentum transfer $\vec{q}$. The new data agree well with previous data which reached $p_{\mathrm{r}}\sim 500$ MeV/c. At ${\theta }_{nq}=35^{\circ }$ and $45^{\circ }$, final state interactions (FSI), meson exchange currents (MEC) and isobar currents (IC) are suppressed and the plane wave impulse approximation (PWIA) provides the dominant cross section contribution. The new data are compared to recent theoretical calculations, where we observe a significant discrepancy for missing momenta $p_{\mathrm{r}}>700$ MeV/c.

   nucl-exPRL(2020)·20 citations
6. 06*

   Impressions of the Continuum Bound State Problem in QCD

   Si-Xue Qin🇨🇳 · Craig D. Roberts🇨🇳

   Modern and anticipated facilities will deliver data that promises to reveal the innermost workings of quantum chromodynamics (QCD). In order to fulfill that promise, phenomenology and theory must reach a new level, limiting and overcoming model-dependence, so that clean lines can be drawn that connect the data with QCD itself. Progress in that direction, made using continuum methods for the hadron bound-state problem, is sketched herein.

   ↳ hep-phhep-exhep-latnucl-ex+1Chin.Phys.Lett.(2020)·77 citations
7. 07*

   Diquark Correlations in Hadron Physics: Origin, Impact and Evidence

   M. Yu. Barabanov🇷🇺 · M. A. Bedolla🇲🇽 · W. K. Brooks🇨🇱 · G. D. Cates🇺🇸 · C. Chen🇩🇪 · Y. Chen🇨🇳 · E. Cisbani🇮🇹 · M. Ding🇮🇹 · G. Eichmann🇵🇹 · R. Ent🇺🇸 · J. Ferretti🇫🇮 · R. W. Gothe🇺🇸 and 15 other authors

   The last decade has seen a marked shift in how the internal structure of hadrons is understood. Modern experimental facilities, new theoretical techniques for the continuum bound-state problem and progress with lattice-regularised QCD have provided strong indications that soft quark+quark (diquark) correlations play a crucial role in hadron physics. For example, theory indicates that the appearance of such correlations is a necessary consequence of dynamical chiral symmetry breaking, viz. a corollary of emergent hadronic mass that is responsible for almost all visible mass in the universe; experiment has uncovered signals for such correlations in the flavour-separation of the proton's electromagnetic form factors; and phenomenology suggests that diquark correlations might be critical to the formation of exotic tetra- and penta-quark hadrons. A broad spectrum of such information is evaluated herein, with a view to consolidating the facts and therefrom moving toward a coherent, unified picture of hadron structure and the role that diquark correlations might play.

   ↳ hep-phhep-exhep-latnucl-ex+1PPNP(2021)·190 citations
8. 08*

   Pulse Pileup Rejection Methods Using a Two-Component Gaussian Mixture Model for Fast Neutron Detection with Pulse Shape Discriminating Scintillator

   Andrew Glenn🇺🇸 · Qi Cheng · Alan D. Kaplan🇺🇸 · Ron Wurtz (Lawrence Livermore National Laboratory)

   Pulse shape discriminating scintillator materials in many cases allow the user to identify two basic kinds of pulses arising from two kinds of particles: neutrons and gammas. An uncomplicated solution for building a classifier consists of a two-component mixture model learned from a collection of pulses from neutrons and gammas at a range of energies. Depending on the conditions of data gathered to be classified, multiple classes of events besides neutrons and gammas may occur, most notably pileup events. All these kinds of events are anomalous and, in cases where the class of the particle is in doubt, it is preferable to remove them from the analysis. This study compares the performance of several machine learning and analytical methods for using the scores from the two-component model to identify anomalous events and in particular to remove pileup events. A specific outcome of this study is to propose a novel anomaly score, denoted G, from an unsupervised two-component model that is conveniently distributed on the interval [-1,1].

   ↳ physics.ins-detnucl-exphysics.data-anNucl.Instrum.Meth.A(2021)·2 citations
9. 09*

   Revisiting ${}^{129}$Xe electric dipole moment measurements applying a new global phase fitting approach

   T. Liu · K. Rolfs · I.Fan · S.Haude · W.Kilian🇩🇪 · L. Li · A.Schnabel · J.Voigt🇩🇪 · L.Trahms🇩🇪

   By measuring the nuclear magnetic spin precession frequencies of polarized ${}^{129}$Xe and ${}^3$He, a new upper limit on the ${}^{129}$Xe atomic electric dipole moment (EDM) $d_{\mathrm{A}}{(}^{129}\mathrm{Xe})$ was reported in Phys. Rev. Lett. 123, 143003 (2019). Here, we propose a new evaluation method based on global phase fitting (GPF) for analyzing the continuous phase development of the ${}^3$He-${}^{129}$Xe comagnetometer signal. The Cramer-Rao Lower Bound on the ${}^{129}$Xe EDM for the GPF method is theoretically derived and shows the potential benefit of our new approach. The robustness of the GPF method is verified with Monte-Carlo studies. By optimizing the analysis parameters and adding data that could not be analyzed with the former method, we obtain a result of $d_{\mathrm{A}}{(}^{129}\mathrm{Xe})=1.1\pm 3.6(\mathrm{stat})\pm 2.0(\mathrm{syst})\times 10^{-28}e\mathrm{cm}$ in an unblinded analysis. For the systematic uncertainty analyses, we adopted all methods from the aforementioned PRL publication except the comagnetometer phase drift, which can be omitted using the GPF method. The updated null result can be interpreted as a new upper limit of $|d_{\mathrm{A}}{(}^{129}\mathrm{Xe})|<8.3\times 10^{-28}e\mathrm{cm}$ at the 95\% C.L.

   ↳ physics.atom-phnucl-exNew J.Phys.(2021)·2 citations
10. 10*

    Two-pole structures in a relativistic Friedrichs-Lee-QPC scheme

    Zhi-Yong Zhou🇨🇳 · Zhiguang Xiao🇨🇳

    A general appearance of two-pole structures is exhibited in a relativistic Friedrichs-Lee model combined with a relativistic quark pair creation model in a consistent manner. This kind of two-pole structure could be found when a $q\bar{q}$ state couples to the open-flavor continuum state in the $S$ partial wave. We found that many enigmatic states, such as $f_0(500)/\sigma$, $K_0^{\ast }(700)/\kappa$, $a_0(980)$, $f_0(980)$, $D_0^{\ast }(2300)$, $D_{s0}^{\ast }(2317)$, and $X(3872)$, together with another higher state for each, all result from this kind of two-pole structures. Furthermore, an interesting observation is that this kind of two-pole structure will contribute roughly a total of 180${}^{\circ }$ phase shift for the scattering process in a single channel approximation. This relativistic scheme may provide more insights into the understanding of the properties of non-$q\bar{q}$ state. It is also suggested that such two-pole structure could be a common phenomenon which deserves studying both from theoretical and experimental perspectives.

    ↳ hep-phhep-exhep-latnucl-ex+1EPJC(2021)·24 citations
11. 11*

    Preparation of Isotopically enriched ${}^{112,116,120,124}$Sn targets at VECC

    Ratnesh Pandey · S.Kundu🇮🇳 · K.Banerjee🇮🇳 · C. Bhattacharya🇮🇳 · T.K.Rana · G.Mukherjee🇮🇳 · S.Manna · J.K.Sahoo · H.Pai🇩🇪 · T.K.Ghosh🇮🇳 · Pratap Roy · A.Sen🇮🇳 and 5 other authors

    Resistive heating and mechanical rolling methods have been employed to prepare isotopically enriched thin target foils of 116Sn (~380 \mu g/cm2), 124Sn(~400 \mu g/cm2) and thicker foils of 112Sn (1.7 mg/cm2),120Sn (1.6 mg/cm2),respectively. Preparation of enriched targets with small amount of material, selection of releasing agent for thin targets and separation of deposited material insolvent were among the several challenges while fabrication of the thin targets. Uniformity of the targets has been measured using 241Am {\alpha}-source. NaCl has been used as releasing agent in preparation of the thin targets. These targets have been successfully used in nuclear physics experiments at VECC.

    ↳ physics.ins-detnucl-exVacuum(2022)·1 citation

* 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.