Thu·Feb 10, 2022Thursday·February 10, 2022

1. 01*

   Photo- and Electrocouplings of Nucleon Resonances

   Victor I. Mokeev🇺🇸 · Daniel S. Carman🇺🇸

   Advances in the exploration of the spectrum and structure of the excited states of the nucleon from experiments with electromagnetic probes on proton targets are presented. Impressive progress has been achieved in the studies of exclusive meson photoproduction in experiments with continuous electron beams and with detectors of almost $4\pi$ acceptance. The high-quality data, coupled with the advances in the amplitude analyses of exclusive photo- and hadroproduction data, allow for the observation of several long-awaited new baryon states known previously as the ``missing" resonances. Studies of exclusive meson electroproduction in the resonance region with the CLAS detector at JLab have provided the dominant part of the available world information on exclusive meson electroproduction observables. These data offer unique information on the structure of most well-established excited nucleon states in the mass region up to 1.8~GeV in terms of the evolution of their electroexcitation amplitudes with momentum transfer of the virtual photon. We discuss the impact of these results on the insight into the strong interaction dynamics that underlie the generation of the full spectrum of nucleon resonances of distinctively different structure. These results shed light on the emergence of hadron mass, which is one of the most important and still open problems in the Standard Model. The extension of the nucleon resonance studies in the experiments of the 12-GeV era at JLab with the CLAS12 detector are outlined.

   nucl-exhep-phFew Body Syst.(2022)·40 citations
2. 02*

   Femtosecond pumping of nuclear isomeric states by the Coulomb collision of ions with quivering electrons

   Jie Feng · Wenzhao Wang · Changbo Fu🇨🇳 · Liming Chen · Junhao Tan · Yaojun Li · Jinguang Wang · Yifei Li🇨🇳 · Guoqiang Zhang🇨🇳 · Yugang Ma🇨🇳 · Jie Zhang

   Efficient production of nuclear isomers is critical for pioneering applications, like nuclear clocks, nuclear batteries, clean nuclear energy, and nuclear {\gamma}-ray lasers. However, due to small production cross sections and quick decays, it is extremely difficult to acquire a significant amount of isomers with short lifetimes via traditional accelerators or reactors because of low beam intensity. Here, for the first time, we experimentally present femtosecond pumping of nuclear isomeric states by the Coulomb excitation of ions with the quivering electrons induced by laser fields. Nuclei populated on the third excited state of 83Kr are generated with a peak efficiency of 2.34*10^15 particles=s from a tabletop hundred-TW laser system. It can be explained by the Coulomb excitation of ions with the quivering electrons during the interaction between laser pulses and clusters at nearly solid densities. This efficient and universal production method can be widely used for pumping isotopes with excited state lifetimes down to picoseconds, and could be a benefit for fields like nuclear transition mechanisms and nuclear {\gamma}-ray lasers.

   nucl-exphysics.plasm-phPRL·34 citations
3. 03*

   New Constraint on the Local Relic Neutrino Background Overdensity with the First KATRIN Data Runs

   M. Aker · D. Batzler · A. Beglarian · J. Behrens · A. Berlev · U. Besserer · B. Bieringer · F. Block · S. Bobien · B. Bornschein · L. Bornschein · M. Böttcher and 120 other authors

   We report on the direct cosmic relic neutrino background search from the first two science runs of the KATRIN experiment in 2019. Beta-decay electrons from a high-purity molecular tritium gas source are analyzed by a high-resolution MAC-E filter around the kinematic endpoint at 18.57 keV. The analysis is sensitive to a local relic neutrino overdensity of 9.7e10 (1.1e11) at a 90% (95%) confidence level. A fit of the integrated electron spectrum over a narrow interval around the kinematic endpoint accounting for relic neutrino captures in the Tritium source reveals no significant overdensity. This work improves the results obtained by the previous kinematic neutrino mass experiments at Los Alamos and Troitsk. We furthermore update the projected final sensitivity of the KATRIN experiment to <1e10 at 90% confidence level, by relying on updated operational conditions.

   nucl-exastro-ph.COhep-exPRL(2022)·72 citations
4. 04*

   Nuclear Spectroscopy with Heavy Ion Nucleon Knockout and (p,2p) Reactions

   Jianguo Li🇰🇷 · Carlos A. Bertulani🇺🇸 · Furong Xu🇨🇳

   Knockout reactions with heavy ion targets in inverse kinematics, as well as "quasi-free" (p,2p) and (p,pn) reactions are useful tools for nuclear spectroscopy. We report calculations on \textit{ab-initio} many-body wavefunctions based on the no-core shell model to study the nucleon removal reactions in light nuclei, including beryllium, carbon, and oxygen isotopic chains, and explore the importance of using an \textit{ab-initio} method. Our study helps clarifying how the extraction of spectroscopic factors from the experiments depend on the details of the many-body wavefunctions being probed. We show that recent advances with the ab-initio method can provide more insights on the spectroscopy information extracted from experiments.

   ↳ nucl-thnucl-exPRC(2022)·18 citations
5. 05*

   Radiative corrections to elastic muon-proton scattering at low momentum transfers

   Norbert Kaiser🇩🇪 · Yong-Hui Lin🇩🇪 · Ulf-G. Meißner🇩🇪

   We systematically calculate the radiative corrections of order $\alpha /\pi$ to elastic muon-proton scattering at low momentum transfers. These include vacuum polarization, photon-loop form factors of the muon and the proton, two-photon exchange corrections and soft photon radiation. In particular, we discuss these corrections for the kinematics of the upcomimg AMBER experiment with a $100$GeV muon beam energy. It is found that for the ratio to the Born cross section, only the minor terms from the photon-loop form factors of the proton and two-photon exchange depend on the proton structure predetermined by the strong interactions. Since a prominent role among the radiative corrections is played by soft photon radiation, the calculation of the bremsstrahlung process $\mu p\to \mu p\gamma$ should be extended beyond the soft photon approximation and tailored to the specific experimental conditions.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2022)·9 citations
6. 06*

   u-Channel Color Transparency Observables

   G.M. Huber🇨🇦 · W.B. Li🇺🇸 · W. Cosyn🇺🇸 · B. Pire🇫🇷

   We propose to study the onset of color transparency in hard exclusive reactions in the backward regime. Guided by the encouraging JLab results on backward pion and omega electro-production data at moderate Q^2, which may be interpreted as the signal of an early scaling regime where the scattering amplitude factorizes in a hard coefficient function convoluted with nucleon to meson transition distribution amplitudes, we show that the study of these channels on nuclear targets opens a new opportunity to test the appearance of nuclear color transparency for a fast moving nucleon.

   ↳ hep-phnucl-exnucl-thMDPI Physics(2022)·13 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.