Nuclear Experiment·nucl-ex
4 papers—1 primary·3 cross-listed·reconstructed*
Saehanseul Oh (for the STAR Collaboration)🇺🇸
These proceeding present recent measurements by the STAR Collaboration of jet production in p+p and Au+Au collisions at sqrt(sNN) = 200 GeV. We focus on jet yields, substructure, and heavy-flavor production, and their modification in the Quark-Gluon Plasma due to jet quenching.
Sota Yoshida🇯🇵 · Noritaka Shimizu🇯🇵
Shell-model calculations play a key role in elucidating various properties of nuclei. In general, those studies require a huge number of calculations to be repeated for parameter calibration and quantifying uncertainties. To reduce the computational burden, we propose a new workflow of shell-model calculations using a method called eigenvector continuation (EC). It enables us to efficiently approximate the eigenpairs under a given Hamiltonian by previously sampled eigenvectors. We demonstrate the validity of EC as an emulator of the valence shell-model, including first application of EC to electromagnetic transition matrix elements. Furthermore, we propose a new usage of EC: preprocessing, in which we start the Lanczos iterations from the approximate eigenvectors, and demonstrate that this can accelerate subsequent research cycles. With the aid of the EC, the eigenvectors obtained during the parameter optimization are not necessarily to be discarded, even if their eigenvalues are far from the experimental data. Those eigenvectors can become accumulated knowledge.
M. Aker · A. Beglarian · J. Behrens · A. Berlev · U. Besserer · B. Bieringer · F. Block · B. Bornschein · L. Bornschein · M. Böttcher · T. Brunst · T. S. Caldwell and 116 other authors
We report the results of the second measurement campaign of the Karlsruhe Tritium Neutrino (KATRIN) experiment. KATRIN probes the effective electron anti-neutrino mass, , via a high-precision measurement of the tritium -decay spectrum close to its endpoint at . In the second physics run presented here, the source activity was increased by a factor of 3.8 and the background was reduced by with respect to the first campaign. A sensitivity on of at confidence level (CL) was reached. This is the first sub-eV sensitivity from a direct neutrino-mass experiment. The best fit to the spectral data yields , resulting in an upper limit of ( CL). By combining this result with the first neutrino mass campaign, we find an upper limit of ( CL).
Peter T. H. Pang🇳🇱 · Ingo Tews🇺🇸 · Michael W. Coughlin🇺🇸 · Mattia Bulla🇸🇪 · Chris Van Den Broeck🇳🇱 · Tim Dietrich🇩🇪
In the past few years, new observations of neutron stars and neutron-star mergers have provided a wealth of data that allow one to constrain the equation of state of nuclear matter at densities above nuclear saturation density. However, most observations were based on neutron stars with masses of about 1.4 solar masses, probing densities up to 3-4 times the nuclear saturation density. Even higher densities are probed inside massive neutron stars such as PSR J0740+6620. Very recently, new radio observations provided an update to the mass estimate for PSR J0740+6620 and X-ray observations by the NICER and XMM telescopes constrained its radius. Based on these new measurements, we revisit our previous nuclear-physics multi-messenger astrophysics constraints and derive updated constraints on the equation of state describing the neutron-star interior. By combining astrophysical observations of two radio pulsars, two NICER measurements, the two gravitational-wave detections GW170817 and GW190425, detailed modeling of the kilonova AT2017gfo, as well as the gamma-ray burst GRB170817A, we are able to estimate the radius of a typical 1.4-solar mass neutron star to be at confidence. Our analysis allows us to revisit the upper bound on the maximum mass of neutron stars and disfavors the presence of a strong first-order phase transition from nuclear matter to exotic forms of matter, such as quark matter, inside neutron stars.
* 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.