Wed·Oct 28, 2020Wednesday·October 28, 2020

1. 01*

   Measurement of ${}^{58}$Ni($p$, $p$)${}^{58}$Ni elastic scattering at low momentum transfer by using the HIRFL-CSR heavy-ion storage ring

   K. Yue · J. T. Zhang🇺🇸 · X. L. Tu🇨🇳 · C. J. Shao · H. X. Li · P. Ma🇨🇳 · B. Mei🇩🇪 · X.C. Chen🇨🇳 · Y. Y. Yang🇨🇳 · X. Q. Liu🇨🇳 · Y. M. Xing🇨🇳 · K. H. Fang and 8 other authors

   The very first in-ring reaction experiment at the HIRFL-CSR heavy-ion storage ring, namely proton elastic scattering on stable ${}^{58}$Ni nuclei, is presented. The circulating ${}^{58}$Ni${}^{19+}$ ions with an energy of 95 MeV/u were interacting repeatedly with an internal hydrogen gas target in the CSRe experimental ring. Low energy proton recoils from the elastic collisions were measured with an ultra-high vacuum compatible silicon-strip detector. Deduced differential cross sections were normalized by measuring K-shell X-rays from ${}^{58}$Ni${}^{19+}$ projectiles due to the ${}^{58}$Ni${}^{19+}$-H${}_2$ ionization collisions. Compared to the experimental cross sections, a good agreement has been achieved with the theoretical predictions in the measured region, which were obtained by using the global phenomenological optical model potentials. Our results enable new research opportunities for optical model potential studies on exotic nuclides by using the in-ring reaction setup at the HIRFL-CSR facility.

   nucl-exPRC(2019)·23 citations
2. 02*

   Particle identification and revolution time corrections for the isochronous mass spectrometry in storage rings

   Y.M. Xing🇨🇳 · Y.H. Zhang · M. Wang🇨🇳 · Yu.A. Litvinov🇩🇪 · R.J. Chen🇨🇳 · X.C. Chen🇨🇳 · C.Y. Fu🇨🇳 · H.F. Li🇨🇳 · P.Shuai🇨🇳 · M. Si🇨🇳 · M.Z. Sun🇨🇳 · X.L. Tu🇨🇳 and 11 other authors

   In the isochronous mass spectrometry (IMS) performed at storage rings, masses of short-lived nuclides are determined through precision measurements of their mean revolution times. However, the distribution of revolution times could be seriously deteriorated by instabilities of the ring's magnetic fields. This becomes a significant obstacle for the particle identifications and mass determinations. A data analysis method is described in this paper which is able to largely remove the uncertainties caused by the magnetic field instabilities in the particle identifications and the mean revolution times. We show that this method is very effective for the IMS experiments even when the magnetic fields of a storage ring vary slowly up to a level of $\Delta B/B\sim 10^{-4}$.

   nucl-exNucl.Instrum.Meth.A(2019)·20 citations
3. 03*

   Observation of Coulomb-assisted nuclear bound state of ${\Xi }^{-}$-${}^{14}$N system

   S.H. Hayakawa (1)🇯🇵 · K. Agari (2)🇯🇵 · J. K. Ahn (3)🇰🇷 · T. Akaishi (4)🇯🇵 · Y. Akazawa (2)🇯🇵 · S. Ashikaga (1 and 5)🇯🇵 · B. Bassalleck (6)🇺🇸 · S. Bleser (7)🇩🇪 · H. Ekawa (8)🇯🇵 · Y. Endo (9)🇯🇵 · Y. Fujikawa (5)🇯🇵 · N. Fujioka (10)🇯🇵 and 86 other authors

   In an emulsion-counter hybrid experiment performed at J-PARC, a ${\Xi }^{-}$ absorption event was observed which decayed into twin single-$\Lambda$ hypernuclei. Kinematic calculations enabled a unique identification of the reaction process as ${\Xi }^{-}{+}^{14}$N$\to {}_{\Lambda }^{10}$Be + ${}_{\Lambda }^5$He. For the binding energy of the ${\Xi }^{-}$ hyperon in the ${\Xi }^{-}$-${}^{14}$N system a value of $1.27\pm 0.21$ MeV was deduced. The energy level of ${\Xi }^{-}$ is likely a nuclear $1p$ state which indicates a weak $\Xi N$-$\Lambda \Lambda$ coupling.

   nucl-exPRL(2021)·85 citations
4. 04*

   Extension of the Hauser-Feshbach Fission Fragment Decay Model to Multi-Chance Fission

   A.E. Lovell🇺🇸 · T. Kawano🇺🇸 · S. Okumura🇦🇹 · I. Stetcu🇺🇸 · M.R. Mumpower🇺🇸 · P. Talou🇺🇸

   The Hauser-Feshbach fission fragment decay model, $\mathtt{H}{\mathtt{F}}^3\mathtt{D}$, which calculates the statistical decay of fission fragments, has been expanded to include multi-chance fission, up to neutron incident energies of 20 MeV. The deterministic decay takes as input pre-scission quantities - fission probabilities and the average energy causing fission - and post-scission quantities - yields in mass, charge, total kinetic energy, spin, and parity. From these fission fragment initial conditions, the full decay is followed through both prompt and delayed particle emissions, allowing for the calculation of prompt neutron and $\gamma$ properties, such as multiplicity and energy distributions, both independent and cumulative fission yields, and delayed neutron observables. In this work, we describe the implementation of multi-chance fission into the $\mathtt{H}{\mathtt{F}}^3\mathtt{D}$ model, and show an example of prompt and delayed quantities beyond first-chance fission, using the example of neutron-induced fission on ${}^{235}$U. This expansion represents significant progress in consistently modeling the emission of prompt and delayed particles from fissile systems.

   ↳ nucl-thnucl-exPRC(2021)·40 citations
5. 05*

   Corrections of order O(E^2_e/m^2_N), caused by weak magnetism and proton recoil, to the neutron lifetime and correlation coefficients of the neutron beta decay

   A. N. Ivanov🇦🇹 · R. Höllwieser🇦🇹 · N. I. Troitskaya🇦🇹 · M. Wellenzohn🇦🇹 · Ya. A. Berdnikov🇷🇺

   We calculate the contributions of weak magnetism and proton recoil of order O(E^2_e/m^2_N)~10^{-5}, i.e. to next-to-next-to-leading order in the large nucleon mass expansion, to the neutron lifetime and correlation coefficients of the neutron beta decay, where E_e and m_N are the electron energy and the nucleon mass, respectively. We analyze the electron-energy and angular distribution for the neutron beta decay with a polarized neutron, a polarized electron and an unpolarized proton. Together with Wilkinson's corrections (Nucl. Phys. A 377, 474 (1982) and radiative corrections of order O(alpha E_e/m_N) ~ 10^{-5} (Phys. Rev. D 99, 093006 (2019)), calculated as next--to--leading order corrections in the large nucleon mass $m_N$ expansion to Sirlin's corrections of order O(alpha/pi) (Phys. Rev. 164, 1767 (1967)), the corrections of order O(E^2_e/m^2_N) ~ 10^{-5} provide an improved level of precision of the theoretical background of the neutron beta decay, calculated in the Standard Model, for experimental searches of contributions of interactions beyond the Standard Model.

   ↳ hep-phnucl-exResults Phys.(2021)·13 citations
6. 06*

   Constraining the density dependence of the symmetry energy: the isospin transport ratio revisited

   S. Mallik · F. Gulminelli

   The isospin diffusion of the quasi-projectile formed in the ${}^{64,58}Ni$ on ${}^{64,58}Ni$ reactions in the Fermi energy domain is investigated in the framework of the Boltzmann-Uehling-Uhlenbeck transport model. The well known isospin transport ratio observable is revisited, with the aim of insuring an optimal comparison between experimental data and theoretical calculations and reducing the present uncertainties in the extraction of empirical equation of state parameters. We show that isospin transport ratios are sensitive to all the low order isovector parameters ($E_{sym}$, $L_{sym}$ and $K_{sym}$). We demonstrate that realistic models of the equation of state, covering the uncertainty that presently affects the theoretical description of neutron stars static observables, can be effectively discriminated by isospin diffusion experiments, provided the neutron to proton ratio of the projectile remnant is precisely measured as a function of centrality.

   ↳ nucl-thnucl-exJ.Phys.G(2022)·9 citations
7. 07*

   Jet transport coefficient $\hat{q}$ in lattice QCD

   Amit Kumar (Wayne State University and McGill University)🇺🇸 · Abhijit Majumder (Wayne State University)🇺🇸 · Johannes Heinrich Weber (Michigan State University and Humboldt University of Berlin)🇩🇪

   We present the first calculation of the jet transport coefficient $\hat{q}$ in quenched and (2+1)-flavor QCD on a 4-D Euclidean lattice. The light-like propagation of an energetic parton is factorized from the mean square gain in momentum transverse to the direction of propagation, which is expressed in terms of the thermal field-strength field-strength correlator. The leading-twist term in its operator product expansion is calculated on the lattice. Continuum extrapolated quenched results, and full QCD estimates based on un-renormalized lattice data, over multiple lattice sizes, are compared with (non) perturbative calculations and phenomenological extractions of $\hat{q}$. The lattice data for $\hat{q}$ show a temperature dependence similar to the entropy density. Within uncertainties, these are consistent with phenomenological extractions, contrary to calculations using perturbation theory.

   ↳ hep-lathep-phnucl-exnucl-thPRD(2022)·41 citations
8. 08*

   Combined Explanation of the $Z\to b\bar{b}$ Forward-Backward Asymmetry, the Cabibbo Angle Anomaly, $\tau \to \mu \nu \nu$ and $b\to s{\ell }^{+}{\ell }^{-}$ Data

   Andreas Crivellin🇨🇭 · Claudio Andrea Manzari🇨🇭 · Marcel Alguero🇪🇸 · Joaquim Matias🇪🇸

   In this article we propose a simple model which can provide a combined explanation of the $Z\to b\bar{b}$ forward-backward asymmetry, the Cabibbo Angle Anomaly (CAA), $\tau \to \mu \nu \nu$ and $b\to s{\ell }^{+}{\ell }^{-}$ data. This model is obtained by extending the Standard Model (SM) by two heavy vector-like quarks (an $SU(2{)}_L$ doublet (singlet) with hypercharge $-5/6$ (-1/3)), two new scalars (a neutral and a singly charged one) and a gauged $L_{\mu }-L_{\tau }$ symmetry. The mixing of the new quarks with the SM ones, after electroweak symmetry breaking, does not only explain $Z\to b\bar{b}$ data but also generates a lepton flavour universal contribution to $b\to s{\ell }^{+}{\ell }^{-}$ transitions. Together with the lepton flavour universality violating effect, generated by loop-induced $Z^{\prime }$ penguins involving the charged scalar and the heavy quarks, it gives an excellent fit to data ($6.1\sigma$ better than the SM). Furthermore, the charged scalar (neutral vector) gives a necessarily constructive tree-level (loop) effect in $\mu \to e\nu \nu$ ($\tau \to \mu \nu \nu$), which can naturally account for the CAA ($\mathrm{Br}[\tau \to \mu \nu \nu ]/\mathrm{Br}[\tau \to e\nu \nu ]$ and $\mathrm{Br}[\tau \to \mu \nu \nu ]/\mathrm{Br}[\mu \to e\nu \nu ]$).

   ↳ hep-phhep-exnucl-exnucl-thPRL(2021)·67 citations
9. 09*

   Denoising scheme based on singular-value decomposition for one-dimensional spectra and its application in precision storage-ring mass spectrometry

   X. C. Chen🇨🇳 · Yu. A. Litvinov🇩🇪 · M. Wang🇨🇳 · Q. Wang🇨🇳 · Y. H. Zhang🇨🇳

   This work concerns noise reduction for one-dimensional spectra in the case that the signal is corrupted by an additive white noise. The proposed method starts with mapping the noisy spectrum to a partial circulant matrix. In virtue of singular-value decomposition of the matrix, components belonging to the signal are determined by inspecting the total variations of left singular vectors. Afterwards, a smoothed spectrum is reconstructed from the low-rank approximation of the matrix consisting of the signal components only. The denoising effect of the proposed method is shown to be highly competitive among other existing nonparametric methods, including moving average, wavelet shrinkage, and total variation. Furthermore, its applicable scenarios in precision storage-ring mass spectrometry are demonstrated to be rather diverse and appealing.

   ↳ physics.data-annucl-exPRE(2019)·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.