Tue·Sep 6, 2022Tuesday·September 6, 2022

1. 01*

   First Observation of Large Missing-Momentum (e,e'p) Cross-Section Scaling and the onset of Correlated-Pair Dominance in Nuclei

   I. Korover · A.W. Denniston · A. Kiral · A. Schmidt · A. Lovato · N. Rocco · A. Nikolakopoulos · L.B. Weinstein · E. Piasetzky · O. Hen · the CLAS Collaboration

   We report the first measurement of $x_B$-scaling in $(e,e^{\prime }p)$ cross-section ratios off nuclei relative to deuterium at large missing-momentum of $350\le p_{miss}\le 600$ MeV/c. The observed scaling extends over a kinematic range of $0.7\le x_B\le 1.8$, which is significantly wider than $1.4\le x_B\le 1.8$ previously observed for inclusive $(e,e^{\prime })$ cross-section ratios. The $x_B$-integrated cross-section ratios become constant (i.e., scale) beginning at $p_{miss}\approx k_F$, the nuclear Fermi momentum. Comparing with theoretical calculations we find good agreement with Generalized Contact Formalism calculations for high missing-momentum ($>375$ MeV/c), suggesting the observed scaling results from interacting with nucleons in short-range correlated (SRC) pairs. For low missing-momenta, mean-field calculations show good agreement with the data for $p_{miss}\le k_F$, and suggest that contributions to the measured cross-section ratios from scattering off single, un-correlated, nucleons are non-negligible up to $p_{miss}\approx 350$ MeV/c. Therefore, SRCs become dominant in nuclei at $p_{miss}\approx 350$ MeV/c, well above the nuclear Fermi Surface of $k_F\approx 250$ MeV/c.

   nucl-exnucl-thPRC(2023)·16 citations
2. 02*

   Search for exotic physics in double-$\beta$ decays with GERDA Phase II

   The GERDA collaboration: M. Agostini · A. Alexander · G. Araujo · A.M. Bakalyarov · M. Balata · I. Barabanov · L. Baudis · C. Bauer · S. Belogurov · A. Bettini · L. Bezrukov · V. Biancacci and 101 other authors

   A search for Beyond the Standard Model double-$\beta$ decay modes of ${}^{76}$Ge has been performed with data collected during the Phase II of the GERmanium Detector Array (GERDA) experiment, located at Laboratori Nazionali del Gran Sasso of INFN (Italy). Improved limits on the decays involving Majorons have been obtained, compared to previous experiments with ${}^{76}$Ge, with half-life values on the order of 10${}^{23}$ yr. For the first time with ${}^{76}$Ge, limits on Lorentz invariance violation effects in double-$\beta$ decay have been obtained. The isotropic coefficient ${\mathring{a}}_{\text{of}}^{(3)}$, which embeds Lorentz violation in double-$\beta$ decay, has been constrained at the order of $10^{-6}$ GeV. We also set the first experimental limits on the search for light exotic fermions in double-$\beta$ decay, including sterile neutrinos.

   nucl-exhep-exJCAP(2022)·21 citations
3. 03*

   Nuclear masses and the equation of state of nuclear matter

   Kazuhiro Oyamatsu

   The incompressible liquid-drop (ILD) model reproduces masses of stable nuclei rather well. Here we show how the ILD volume, surface, symmetry, and Coulomb energies are related to the equation of state of nuclear matter using the Oyamatsu-Iida (OI) macroscopic nuclear model, which has reasonable many-body energy and isoscalar inhomogeneity gradient energy. We use 304 update interactions, covering wide ranges of the incompressibility $K_0$ of symmetric matter and the density slope of symmetry energy $L$, which fit almost equally empirical mass and radius data of stable nuclei. Thus, the $K_0$ and $L$ dependences are nearly frozen in stable nuclei as in the ILD model, leading to clear correlations among interaction and saturation parameters. Furthermore, we assume that the surface energy of the OI model is twice as large as the gradient energy using the size equilibrium conditions of the ILD and OI models. Then, the four energies of the ILD and OI models agree well for stable nuclei with $A\gtrsim 40$. Meanwhile, the OI model with $L\lesssim 100$ MeV predicts the latest mass data better than those of stable nuclei, and we suggest $20\lesssim L\lesssim 90$ MeV, although the lower boundary is not constrained well.

   ↳ nucl-thnucl-exPTEP(2023)·4 citations
4. 04*

   Has J-PARC E07 observed a ${\Xi }_{1s}^{-}$ nuclear state?

   E. Friedman🇮🇱 · A. Gal🇮🇱

   The Strangeness $\mathcal{S}=-2$ J-PARC E07 emulsion experiment published recently two new ${\Xi }^{-}$--${}^{14}$N capture events, IRRAWADDY and IBUKI, identified by observing weak-decay sequences of pairs of single-$\Lambda$ hypernuclei and interpreted as ${\Xi }_{1s}^{-}$ and ${\Xi }_{1p}^{-}$ nuclear bound states, respectively, with binding energies $B_{{\Xi }^{-}}^{1s}$=6.27$\pm$0.27 MeV and $B_{{\Xi }^{-}}^{1p}$=1.27$\pm$0.21 MeV. ${\Xi }^{-}$ capture events in emulsion play a major role in determining the $\Xi$-nuclear and the $\Lambda \Lambda$ potential strengths. Here we question the assignment of a ${\Xi }_{1s}^{-}$ nuclear bound state to IRRAWADDY and offer an alternative assignment as a near-threshold ${\Xi }_{1p}^0$--${}^{14}$C nuclear bound state, slightly admixed with a ${\Xi }_{1p}^{-}$--${}^{14}$N nuclear bound state component corresponding to IBUKI. We also question using IBUKI's $B_{{\Xi }^{-}}^{1p}$ value as is to determine the $\Xi$-nuclear potential depth. Altogether, ${\Xi }^{-}$ capture events in ${}^{12}$C and ${}^{16}$O should prove less ambiguous than in ${}^{14}$N.

   ↳ nucl-thhep-phnucl-exPLB(2023)·16 citations
5. 05*

   The Nucleon Energy Correlators

   Xiaohui Liu🇨🇳 · Hua Xing Zhu🇨🇳

   We introduce the concept of the nucleon energy correlators, a set of novel objects that encode the microscopic details of a nucleon, such as the parton angular distribution in a nucleon, the collinear splitting to all orders, as well as the internal transverse dynamics of the nucleon. The nucleon energy correlators complement the conventional nucleon/nucleus tomography, but without introducing the non-perturbative fragmentation functions or the jet clustering algorithms. We demonstrate how the nucleon energy correlators can be measured in the lepton-nucleon deep inelastic scattering. The predicted distributions display a fascinating phase transition between the perturbative and non-perturbative regime. In the perturbative phase, a polar angle version of the Bjorken scaling behavior is predicted. We discuss its possible applications and expect it aggrandize the physics content at the electron ion colliders with a far-forward detector.

   ↳ hep-phhep-exnucl-exPRL(2023)·85 citations
6. 06*

   The CERN n TOF NEAR station for astrophysics- and application-related neutron activation measurements

   N. Patronis · A. Mengoni · N. Colonna · M. Cecchetto · C. Domingo-Pardo · O. Aberle · J. Lerendegui-Marco · G. Gervino · M.E. Stamati · S. Goula · A.P. Bernardes · M. Mastromarco and 121 other authors

   A new experimental area, the NEAR station, has recently been built at the CERN n TOF facility, at a short distance from the spallation target (1.5 m). The new area, characterized by a neutron beam of very high flux, has been designed with the purpose of performing activation measurements of interest for astrophysics and various applications. The beam is transported from the spallation target to the NEAR station through a hole in the shielding wall of the target, inside which a collimator is inserted. The new area is complemented with a {\gamma}-ray spectroscopy laboratory, the GEAR station, equipped with a high efficiency HPGe detector, for the measurement of the activity resulting from irradiation of a sample in the NEAR station. The use of a moderator/filter assembly is envisaged, in order to produce a neutron beam of Maxwellian shape at different thermal energies, necessary for the measurement of Maxwellian Averaged Cross Sections of astrophysical interest. A new fast-cycling activation technique is also being investigated, for measurements of reactions leading to isotopes of very short half life.

   ↳ physics.ins-detastro-ph.IMnucl-exEPJA(2025)·16 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.