Tue·Jun 14, 2022Tuesday·June 14, 2022

1. 01*

   Scaling Properties of the $\Delta \gamma$ Correlator: Constraints on Background and CME-Sensitive Charge Separation in Heavy-Ion Collisions

   Roy A. Lacey (1) · Niseem Magdy (2) ((1) Depts. of Chemistry and Physics, Stony Brook University, Stony Brook, New York 11794, USA (2) Dept. of Physics, Texas Southern University, Houston, TX 77004, USA)

   The scaling properties of the $\Delta \gamma$ correlator are used to investigate charge separation associated with the chiral magnetic effect (CME) in $p$+Au, $d$+Au, Ru+Ru, Zr+Zr, and Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=200$~GeV, and in $p$+Pb and Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ and $2.76$~TeV. Anomalous Viscous Fluid Dynamics (AVFD) calculations provide complementary benchmarks for background and signal+background behavior. Scaling $\Delta \gamma$ by the elliptic-flow coefficient $v_2$ reduces the leading flow-coupled background dependence, while the resulting $\Delta \gamma /v_2$ exhibits a common approximate $1/N_{\mathrm{ch}}$ scaling behavior for $p$+Au, $d$+Au, $p$+Pb, and Pb+Pb collisions, consistent with multiplicity dilution of background-driven charge correlations across markedly different collision systems and environments. In contrast, Ru+Ru, Zr+Zr, and Au+Au collisions exhibit systematic positive deviations from their respective $1/N_{\mathrm{ch}}$ background-scaling trends. These scaling violations are qualitatively similar to those generated by AVFD calculations with an input CME signal and, relative to the experimentally constrained background scaling, provide evidence for a CME contribution to the measured charge separation. The inferred CME fraction is approximately $27\%$ for mid-central Au+Au collisions and roughly a factor of two smaller for Ru+Ru and Zr+Zr, whose values are consistent within uncertainties. The inferred CME fractions reduce the expected Ru+Ru--Zr+Zr difference to only $\sim 1.3\%$ in the total charge-separation signal, explaining its limited experimental sensitivity. These results demonstrate that scaling violations relative to an experimentally constrained background provide a quantitative strategy for isolating a CME contribution to charge separation in heavy-ion collisions.

   nucl-exhep-exnucl-th7 citations
2. 02*

   Search for solar axions via axion-photon coupling with the Majorana Demonstrator

   I.J. Arnquist🇺🇸 · F.T. Avignone III🇺🇸 · A.S. Barabash🇷🇺 · C.J. Barton🇺🇸 · K.H. Bhimani🇺🇸 · E. Blalock🇺🇸 · B. Bos🇺🇸 · M. Busch🇺🇸 · M. Buuck🇺🇸 · T.S. Caldwell🇺🇸 · Y-D. Chan🇺🇸 · C.D. Christofferson🇺🇸 and 46 other authors

   Axions were originally proposed to explain the strong-CP problem in QCD. Through the axion-photon coupling, the Sun could be a major source of axions, which could be measured in solid state detection experiments with enhancements due to coherent Primakoff-Bragg scattering. The Majorana Demonstrator experiment has searched for solar axions with a set of ${}^{76}$Ge-enriched high purity germanium detectors using a 33 kg-yr exposure collected between Jan. 2017 and Nov. 2019. A temporal-energy analysis gives a new limit on the axion-photon coupling as $g_{a\gamma }<1.45\times 10^{-9}$ GeV${}^{-1}$ (95% C.I.) for axions with mass up to 100 eV/$c^2$. This improves laboratory-based limits between about 1 eV/$c^2$ and 100 eV/$c^2$.

   nucl-exhep-exPRL(2022)·25 citations
3. 03*

   Constraints on key ${}^{17}$O($\alpha ,\gamma$)${}^{21}$Ne resonances and impact on the weak s-process

   M. Williams🇺🇸 · A.M. Laird🇬🇧 · A. Choplin🇧🇪 · P. Adsley🇿🇦 · B. Davids🇨🇦 · U. Greife🇺🇸 · K. Hudson🇨🇦 · D. Hutcheon · A. Lennarz🇨🇦 · C. Ruiz🇨🇦

   The efficiency of the slow neutron-capture process in massive stars is strongly influenced by neutron-capture reactions on light elements. At low metallicity, ${}^{16}$O is an important neutron absorber, but the effectiveness of ${}^{16}$O as a light-element neutron poison is modified by competition between subsequent ${}^{17}$O$(\alpha ,n{)}^{20}$Ne and ${}^{17}$O$(\alpha ,\gamma {)}^{21}$Ne reactions. The strengths of key ${}^{17}$O$(\alpha ,\gamma {)}^{21}$Ne resonances within the Gamow window for core helium burning in massive stars are not well constrained by experiment. This work presents more precise measurements of resonances in the energy range $E_{c.m.}=612-1319$ keV. We extract resonance strengths of $\omega {\gamma }_{638}=4.85\pm 0.79$ $\mu$eV, $\omega {\gamma }_{721}=13.0_{-2.4}^{+3.3}$ $\mu$eV, $\omega {\gamma }_{814}=7.72\pm 0.55$ meV and $\omega {\gamma }_{1318}=136\pm 13$ meV, for resonances at $E_{c.m.}=$ 638, 721, 814 and 1318 keV, respectively. We also report an upper limit for the 612 keV resonance of $\omega \gamma <140$ neV ($95\%$ c.l.), which effectively rules out any significant contribution from this resonance to the reaction rate. From this work, a new ${}^{17}$O$(\alpha ,\gamma {)}^{21}$Ne thermonuclear reaction rate is calculated and compared to the literature. The effect of present uncertainties in the ${}^{17}$O$(\alpha ,\gamma {)}^{21}$Ne reaction rate on weak s-process yields are then explored using post-processing calculations based on a rotating $20M_{\odot }$ low-metallicity massive star. The resulting ${}^{17}$O$(\alpha ,\gamma {)}^{21}$Ne reaction rate is lower with respect to the pre-existing literature and found to enhance weak s-process yields in rotating massive star models.

   nucl-exastro-ph.SRnucl-thPRC(2022)·5 citations
4. 04*

   New measurement of the $E_{c.m.}=323$ keV resonance in the ${}^{19}$F$($p,\gamma$)$^{20}$Ne reaction

   M. Williams🇨🇦 · P. Adsley🇿🇦 · B. Davids🇨🇦 · U. Greife🇺🇸 · D. Hutcheon🇨🇦 · J. Karpesky🇺🇸 · A. Lennarz🇨🇦 · M. Lovely🇺🇸 · C. Ruiz🇨🇦

   At temperatures below 0.1 GK the ${}^{19}$F$(p,\gamma {)}^{20}$Ne reaction is the only breakout path out of the CNO cycle. Experimental studies of this reaction are challenging from a technical perspective due to copious $\gamma$-ray background from the far stronger ${}^{19}$F$(p,\alpha {)}^{16}$O reaction channel. Here we present the first inverse kinematics study of the ${}^{19}$F$(p,\gamma {)}^{20}$Ne reaction, in which we measure the strength of the 323-keV resonance. We find a strength value of $\omega \gamma =3.3_{-0.9}^{+1.1}$ meV, which is a factor of two larger than the most recent previous study. The discrepancy is likely the result of a direct to ground state transition which previous studies were not sensitive to. We also observe the transition to the first $2^{-}$ state, which has not been observed for this resonance in previous studies. A new thermonuclear reaction rate is calculated and compared with the literature.

   nucl-exastro-ph.SRPRC(2021)·9 citations
5. 05*

   ${\mathrm{f}}_0(980)$ production in inelastic pp collisions at $\sqrt{s}=5.02$ TeV

   ALICE Collaboration

   The measurement of the production of ${\mathrm{f}}_0(980)$ in inelastic pp collisions at $\sqrt{s}=5.02$ TeV is presented. This is the first reported measurement of inclusive ${\mathrm{f}}_0(980)$ yield at LHC energies. The production is measured at midrapidity, $|y|<0.5$, in a wide transverse momentum range, $0<p_{\mathrm{T}}<16$ GeV/$c$, by reconstructing the resonance in the ${\mathrm{f}}_0(980)\to {\pi }^{+}{\pi }^{-}$ hadronic decay channel using the ALICE detector. The $p_{\mathrm{T}}$-differential yields are compared to those of pions, protons and $\varphi$ mesons as well as to predictions from the HERWIG 7.2 QCD-inspired Monte Carlo event generator and calculations from a coalescence model that uses the AMPT model as an input. The ratio of the $p_{\mathrm{T}}$-integrated yield of ${\mathrm{f}}_0(980)$ relative to pions is compared to measurements in ${\mathrm{e}}^{+}{\mathrm{e}}^{-}$ and pp collisions at lower energies and predictions from statistical hadronisation models and HERWIG 7.2. A mild collision energy dependence of the ${\mathrm{f}}_0(980)$ to pion production is observed in pp collisions from SPS to LHC energies. All considered models underpredict the $p_{\mathrm{T}}$-integrated $2{\mathrm{f}}_0(980)/({\pi }^{+}+{\pi }^{-})$ ratio. The prediction from the canonical statistical hadronisation model assuming a zero total strangeness content of ${\mathrm{f}}_0(980)$ is consistent with the data within 1.9$\sigma$ and is the closest to the data. The results provide an essential reference for future measurements of the particle yield and nuclear modification in p$-$Pb and Pb$-$Pb collisions, which have been proposed to be instrumental to probe the elusive nature and quark composition of the ${\mathrm{f}}_0(980)$ scalar meson.

   nucl-exhep-exPLB(2023)·22 citations
6. 06*

   Impact of nuclear deformation on collective flow observables in relativistic U+U collisions

   Niseem Magdy🇺🇸

   A Multi-Phase Transport (AMPT) model is used to investigate the efficacy of several flow observables to constrain the initial-state deformation of the Uranium nuclei in U$+$U collisions at nucleon-nucleon center-of-mass energy $\sqrt{{\text{s}}_{NN}}$ = 193 GeV. The multiparticle azimuthal cumulant method is used to investigate the sensitivity of (I) a set of quantities that are sensitive to both initial- and final-state effects as well as (II) a set of dimensionless quantities that are more sensitive to initial-state effects to the Uranium nuclei quadrupole shape deformation. We find that the combined use of the flow harmonics, flow fluctuations and correlations, linear and non-linear flow correlations to the quadrangular flow harmonic, and the correlations between elliptic flow and the mean-transverse momentum could serve to constrain the nuclear deformation of the Uranium nuclei. Therefore, a comprehensive set of measurements of such observables can provide a quantifying tool for the quadrupole shape deformation via data-model comparisons.

   ↳ nucl-thhep-phnucl-exEPJA(2023)·29 citations
7. 07*

   Direct measurement of the ${}^3$He${}^{+}$ magnetic moments

   A. Schneider🇩🇪 · B. Sikora🇩🇪 · S. Dickopf🇩🇪 · M. Müller🇩🇪 · N. S. Oreshkina🇩🇪 · A. Rischka🇩🇪 · I. A. Valuev🇩🇪 · S. Ulmer🇯🇵 · J. Walz🇩🇪 · Z. Harman🇩🇪 · C. H. Keitel🇩🇪 · A. Mooser🇩🇪 · K. Blaum🇩🇪

   Helium-3 has nowadays become one of the most important candidates for studies in fundamental physics [1, 2, 3], nuclear and atomic structure [4, 5], magnetometry and metrology [6] as well as chemistry and medicine [7, 8]. In particular, ${}^3$He nuclear magnetic resonance (NMR) probes have been proposed as a new standard for absolute magnetometry [6, 9]. This requires a high-accuracy value for the ${}^3$He nuclear magnetic moment, which, however, has so far been determined only indirectly and with a relative precision of $12$ parts per billon (p.p.b.) [10,11]. Here we investigate the ${}^3$He${}^{+}$ ground-state hyperfine structure in a Penning trap to directly measure the nuclear $g$-factor of ${}^3$He${}^{+}$ $g_I^{\prime }=-4.2550996069(30{)}_{stat}(17{)}_{sys}$, the zero-field hyperfine splitting $E_{\mathrm{HFS}}^{\exp }=-8665649865.77(26{)}_{stat}(1{)}_{sys}$ Hz and the bound electron $g$-factor $g_e^{\text{exp}}=-2.00217741579(34{)}_{stat}(30{)}_{sys}$. The latter is consistent with our theoretical value $g_e^{\text{theo}}=-2.00217741625223(39)$ based on parameters and fundamental constants from [12]. Our measured value for the ${}^3$He${}^{+}$ nuclear $g$-factor allows for the determination of the $g$-factor of the bare nucleus $g_I=-4.2552506997(30{)}_{stat}(17{)}_{sys}(1{)}_{theo}$ via our accurate calculation of the diamagnetic shielding constant [13] ${\sigma }_{{}^{3}H{e}^{+}}=0.00003550738(3)$. This constitutes the first direct calibration for ${}^3$He NMR probes and an improvement of the precision by one order of magnitude compared to previous indirect results. The measured zero-field hyperfine splitting improves the precision by two orders of magnitude compared to the previous most precise value [14] and enables us to determine the Zemach radius [15] to $r_Z=2.608(24)$ fm.

   ↳ physics.atom-phnucl-exNature(2022)·41 citations
8. 08*

   Laurent+Pietarinen Partial Wave Analysis

   A. Svarc🇭🇷 · R. L. Workman🇺🇸

   A new energy-dependent fit strategy, independent of any specific microscopic theory, is applied to kaon photoproduction data with center-of-mass energies ranging from 1625 MeV to 2296 MeV. Experimental data are fitted in terms of a modified Laurent expansion (Laurent+Pietarinen expansion) which previously has been successfully applied to multipoles. The present aim is to extract resonance pole parameters directly from the data, rather than from sets of multipoles. A constrained single-energy fit is then used to search for missing structures. In this proof-of-principle study, the data are well-described by the initial L+P fit, and it is shown that only a moderate amount of structure, mostly in higher multipoles, is missing from the original fit. Problems due to an unmeasurable overall phase, plaguing single-channel multipole analyses, are mitigated by implementing a form of phase limitation, fixing the initial values of fit parameters using a multi-channel analysis.

   ↳ nucl-thnucl-exPRC(2023)·4 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.