Wed·Dec 23, 2020Wednesday·December 23, 2020

1. 01*

   Measurement of the 2$\nu \beta \beta$ Decay Half-life of ${}^{130}$Te with CUORE

   CUORE Collaboration: D. Q. Adams🇺🇸 · C. Alduino🇺🇸 · K. Alfonso🇺🇸 · F. T. Avignone III🇺🇸 · O. Azzolini🇮🇹 · G. Bari🇮🇹 · F. Bellini🇮🇹 · G. Benato🇮🇹 · M. Biassoni🇮🇹 · A. Branca🇮🇹 · C. Brofferio🇮🇹 · C. Bucci🇮🇹 and 100 other authors

   We measured two-neutrino double beta decay of ${}^{130}$Te using an exposure of 300.7 kg$\cdot$yr accumulated with the CUORE detector. Using a Bayesian analysis to fit simulated spectra to experimental data, it was possible to disentangle all the major background sources and precisely measure the two-neutrino contribution. The half-life is in agreement with past measurements with a strongly reduced uncertainty: $T_{1/2}^{2\nu }=7.71_{-0.06}^{+0.08}{(stat.)}_{-0.15}^{+0.12}(syst.)\times 10^{20}$ yr. This measurement is the most precise determination of the ${}^{130}$Te 2$\nu \beta \beta$ decay half-life to date.

   nucl-exPRL(2021)·61 citations
2. 02*

   Comprehensive test of the Brink-Axel hypothesis in the energy region of the pygmy dipole resonance

   M. Markova (1)🇳🇴 · P. von Neumann-Cosel (2)🇩🇪 · A. C. Larsen (1)🇳🇴 · S. Bassauer (2) · A. Görgen (2)🇳🇴 · M. Guttormsen (1)🇳🇴 · F. L. Bello Garrote (1)🇳🇴 · H. C. Berg (1) · M. M. Bjørøen (1) · T. Dahl-Jacobsen (1) · T. K. Eriksen (1)🇦🇺 · D. Gjestvang (1) and 13 other authors

   The validity of the Brink-Axel hypothesis, which is especially important for numerous astrophysical calculations, is addressed for 116,120,124Sn below the neutron separation energy by means of three independent experimental methods. The $\gamma$-ray strength functions (GSFs) extracted from primary $\gamma$-decay spectra following charged-particle reactions with the Oslo method and with the Shape method demonstrate excellent agreement with those deduced from forward-angle inelastic proton scattering at relativistic beam energies. In addition, the GSFs are shown to be independent of excitation energies and spins of the initial and final states. The results provide a critical test of the generalized Brink-Axel hypothesis in heavy nuclei, demonstrating its applicability in the energy region of the pygmy dipole resonance.

   nucl-exnucl-thPRL(2021)·27 citations
3. 03*

   Electromagnetic form factors of the ${\Omega }^{-}$ baryon in the spacelike and timelike regions

   G. Ramalho🇧🇷

   We present complete calculations of the electromagnetic form factors of the ${\Omega }^{-}$ in the spacelike region and in the timelike region. The four elastic form factors: electric charge ($G_{E0}$), magnetic dipole ($G_{M1}$), electric quadrupole ($G_{E2}$) and magnetic octupole ($G_{M3}$), are estimated within the covariant spectator quark model, in terms of the square momentum transfer $q^2$. The free parameters of the ${\Omega }^{-}$ wave function, including a $S$-wave state and two independent $D$-wave states radial wave functions and the admixture coefficients are fixed by the comparison with the lattice QCD data in the spacelike region ($Q^2=-q^2\le 0$) and with the recent $e^{+}{e}^{-}\to {\Omega }^{-}{\bar{\Omega }}^{+}$ data from CLEO in the timelike region ($q^2>0$). The estimates in the timelike region for square momentum transfer $q^2\ge 4M_{\Omega }^2$ are based on large-$q^2$ asymptotic relations ($M_{\Omega }$ is the ${\Omega }^{-}$ mass). We examine also the impact of the large-$Q^2$ correlations between different form factors and analyze the possible solutions. The electric quadrupole and the magnetic octupole moments of the ${\Omega }^{-}$, and the $e^{+}{e}^{-}\to {\Omega }^{-}{\bar{\Omega }}^{+}$ integrated cross sections for very large $q^2$ are estimated based on the model results.

   ↳ hep-phhep-exhep-latnucl-ex+1PRD(2021)·22 citations
4. 04*

   Neutron State Entanglement with Overlapping Paths

   S. J. Kuhn · S. McKay · J. Shen🇺🇸 · N. Geerits · R. M. Dalgliesh · E. Dees🇺🇸 · A. A. M. Irfan · F. Li🇨🇳 · S. Lu · V. Vangelista · D. V. Baxter · G. Ortiz and 3 other authors

   The development of direct probes of entanglement is integral to the rapidly expanding field of complex quantum materials. Here we test the robustness of entangled neutrons as a quantum probe by measuring the Clauser-Horne-Shimony-Holt contextuality witness while varying the beam properties. Specifically, we prove that the entanglement of the spin and path subsystems of individual neutrons prepared in two different experiments using two different apparatuses persists even after varying the entanglement length, coherence length, and neutron energy difference of the paths. The two independent apparatuses acting as entangler-disentangler pairs are static-field magnetic Wollaston prisms and resonance-field radio frequency flippers. Our results show that the spatial and energy properties of the neutron beam may be significantly altered without reducing the contextuality witness value below the Tsirelson bound, meaning that maximum entanglement is preserved. We also show that two paths may be considered distinguishable even when separated by less than the neutron coherence length. This work is the key step in the realization of the new modular, robust technique of entangled neutron scattering.

   ↳ quant-phcond-mat.mes-hallcond-mat.othercond-mat.str-el+1PRResearch(2021)·20 citations
5. 05*

   Nuclear charge-exchange excitations based on relativistic density-dependent point-coupling model

   D. Vale · Y. F. Niu🇨🇳 · N. Paar🇭🇷

   Spin-isospin transitions in nuclei away from the valley of stability are essential for the description of astrophysically relevant weak interaction processes. While they remain mainly beyond the reach of experiment, theoretical modeling provides important insight into their properties. In order to describe the spin-isospin response,vcthe proton-neutron relativistic quasiparticle random phase approximation (PN-RQRPA) is formulated using the relativistic density-dependent point coupling interaction, and separable pairing interaction in both the $T=1$ and $T=0$ pairing channels. By implementing recently established DD-PCX interaction with improved isovector properties relevant for the description of nuclei with neutron-to-proton number asymmetry, the isobaric analog resonances (IAR) and Gamow-Teller resonances (GTR) have been investigated. In contrast to other models that usually underestimate the IAR excitation energies in Sn isotope chain, the present model accurately reproduces the experimental data, while the GTR properties depend on the isoscalar pairing interaction strength. This framework provides not only an improved description of the spin-isospin response in nuclei, but it also allows future large scale calculations of charge-exchange excitations and weak interaction processes in stellar environment.

   ↳ nucl-thnucl-exPRC(2021)·22 citations
6. 06*

   Beam particle tracking with a low-mass mini time projection chamber in the PEN experiment

   C.J. Glaser🇺🇸 · D. Pocanic🇺🇸 · A. van der Schaaf🇨🇭 · V.A. Baranov🇷🇺 · N.V. Khomutov🇷🇺 · N.P. Kravchuk🇷🇺 · N.A. Kuchinsky🇷🇺

   The international PEN collaboration aims to obtain the branching ratio for the pion electronic decay ${\pi }^{+}\to e^{+}{\nu }_e(\gamma )$, aka ${\pi }_{e2}$, to a relative precision of $5\times 10^{-4}$ or better. The PEN apparatus comprises a number of detection systems, all contributing vital information to the PEN event reconstruction. This paper discusses the design, performance, and Monte Carlo simulation of the mini time projection chamber (mTPC) used for pion, muon, and positron beam particle tracking. We also review the use of the extracted trajectory coordinates in the analysis, in particular in constructing observables critical for discriminating background processes, and in maximizing the fiducial volume of the target in which decay event vertices can be accepted for branching ratio extraction without introducing bias.

   ↳ physics.ins-dethep-exhep-phnucl-exNucl.Instrum.Meth.A(2021)·2 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.