Nuclear Experiment·nucl-ex
6 papers—3 primary·3 cross-listed·reconstructed*
Pawel Moskal🇵🇱 · Magdalena Skurzok🇵🇱 · Wojciech Krzemien🇵🇱
In this report the search for eta-mesic nuclei is reviewed. The brief description of the experimental studies is presented with a focus on the possible production of the eta-nucleus bound states for light nuclei like 4He and 3He.
V. Derya🇩🇪 · N. Tsoneva🇩🇪 · T. Aumann🇩🇪 · M. Bhike · J. Endres🇩🇪 · M. Gooden🇺🇸 · A. Hennig🇩🇪 · J. Isaak · H. Lenske🇩🇪 · B. Löher🇩🇪 · N. Pietralla🇩🇪 · D. Savran🇩🇪 and 3 other authors
Background: Two-phonon excitations originating from the coupling of two collective one-phonon states are of great interest in nuclear structure physics. One possibility to generate low-lying excitations is the coupling of quadrupole and octupole phonons. Purpose: In this work, the -decay behavior of candidates for the state in the doubly-magic nucleus Ca and in the heavier and semi-magic nucleus Ce is investigated. Methods: experiments have been carried out at the High Intensity -ray Source (HIS) facility in combination with the high-efficiency -ray spectroscopy setup consisting of HPGe and LaBr detectors. The setup enables the acquisition of - coincidence data and, hence, the detection of direct decay paths. Results: In addition to the known ground-state decays, for Ca the decay into the state was observed, while for Ce the direct decays into the and the state were detected. The experimentally deduced transition strengths and excitation energies are compared to theoretical calculations in the framework of EDF theory plus QPM approach and systematically analyzed for isotones. In addition, negative parities for two states in Ca were deduced simultaneously. Conclusions: The experimental findings together with the theoretical calculations support the two-phonon character of the excitation in the light-to-medium-mass nucleus Ca as well as in the stable even-even nuclei.
J.P. Lansberg · M. Anselmino · R. Arnaldi · S.J. Brodsky · V. Chambert · J.P. Didelez · M.G Echevarria · E.G. Ferreiro · F. Fleuret · Y. Gao · B. Genolini · C. Hadjidakis and 18 other authors
We review a number of ideas put forward in favour of the use of a polarised target along with the proposed idea of a fixed-target experiment using the LHC beams -- AFTER@LHC. A number of recent studies have shown that single transverse-spin asymmetries (STSAs) are large enough to be precisely measured in the region accessible with AFTER@LHC, in particular as regards the Drell-Yan process as well as single-pion, isolated-photon and jet production. AFTER@LHC with a polarised target would also be the ideal experimental set-up to measure the gluon Sivers effect via a number of original quarkonium STSA studies. We discuss first figures-of-merit based on simulations for AFTER@LHC with a polarised target.
By deriving a general expression for multiplicity distribution (a conditional probability distribution) in statistical model, we demonstrate the mismatches between experimental measurements and previous theoretical calculations on multiplicity fluctuations. From the corrected formula, we develop an improved baseline measure for multiplicity distribution under Poisson approximation in statistical model to replace the traditional Poisson expectations. We find that the ratio of the mean multiplicity to the corresponding reference multiplicity are crucial to systemically explaining the measured scale variances of total charge distributions in different experiments, as well as understanding the centrality resolution effect observed in experiment. The improved statistical expectations, albeit simple, work well in describing the negative binomial multiplicity distribution measured in experiments, e.g. the cumulants (cumulant products) of total (net) electric charge distributions.
Joachim Nsofini🇨🇦 · Dusan Sarenac🇨🇦 · Christopher J. Wood🇺🇸 · David G. Cory🇨🇦 · Muhammad Arif · Charles W. Clark🇺🇸 · Michael G. Huber · Dmitry A. Pushin
We propose a method to prepare an entangled spin-orbit state between the spin and the orbital angular momenta of a neutron wavepacket. This spin-orbit state is created by passing neutrons through the center of a quadrupole magnetic field, which provides a coupling between the spin and orbital degrees of freedom. A Ramsey fringe type measurement is suggested as a means of verifying the spin-orbit correlations.
Bruno El-Bennich🇧🇷 · Gastão Krein🇧🇷 · Eduardo Rojas🇨🇴 · Fernando E. Serna🇧🇷
We highlight Hermiticity issues in bound-state equations whose kernels are subject to a highly asymmetric mass and momentum distribution and whose eigenvalue spectrum becomes complex for radially excited states. We trace back the presence of imaginary components in the eigenvalues and wave functions to truncation artifacts and suggest how they can be eliminated in the case of charmed mesons. The solutions of the gap equation in the complex plane, which play a crucial role in the analytic structure of the Bethe-Salpeter kernel, are discussed for several interaction models and qualitatively and quantitatively compared to analytic continuations by means of complex-conjugate pole models fitted to real solutions.
* 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.