Nuclear Theory·nucl-th

Thursday·May 14, 2020

8 papers—4 primary·4 cross-listed

05
Connection between soft and hard probes of small collision systems at RHIC and LHC
Dennis V. Perepelitsa🇺🇸
The expected connections between signatures in the soft and hard sectors of small collision systems, and the status of experimental attempts to identify them, are discussed. These proceedings summarize the talk as given at the International Symposium on Multi-Particle Dynamics in September 2019 in Santa Fe, NM (ISMD19). As such, the choice of content and focus are selective and not intended to be comprehensive.
↳ nucl-exnucl-thEPJ Web Conf.(2020)·3 citations
06
On the inversion of isobaric-analogue states in nuclei
J. Henderson · S. R. Stroberg
Isospin is an approximate symmetry in atomic nuclei, arising from the rather similar properties of protons and neutrons. Perhaps the clearest manifestation of isospin within nuclei is in the near-identical structure of excited states in mirror nuclei: nuclei with inverted numbers of protons and neutrons. Isospin symmetry, and therefore mirror-symmetry, is broken by electromagnetic interactions and the difference in the masses of the up and down quarks. A recent study by Hoff and collaborators presented evidence that the ground-state spin of $^{73}$ Sr is different from that of its mirror, $^{73}$ Br, due to an inversion of the ground- and first-excited states, separated by only 27 keV in the $^{73}$ Br system. In this brief note, we place this inversion within the necessary context of the past half-century of experimental and theoretical work, and show that it is entirely consistent with normal behaviour, and affords no new insight into isospin-symmetry breaking. The essential point is that isospin-breaking effects due to the Coulomb interaction frequently vary from level to level within a given medium-mass nucleus by as much as 200 keV. Any level splitting smaller than this is liable to manifest a level inversion in the mirror partner which, absent disagreement with an appropriate nuclear model, does not challenge our understanding. While we note the novelty of an inversion in nuclear ground states, we emphasize that in the context of isospin there is nothing specifically illuminating about the ground state, or a level inversion.
↳ nucl-exnucl-thPRC(2020)·13 citations
07
Renormalization group and scattering-equivalent Hamiltonians on a coarse momentum grid
María Gómez-Rocha🇪🇸 · Enrique Ruiz Arriola🇪🇸
We consider the $π π$ -scattering problem in the context of the Kadyshevsky equation. In this scheme, we introduce a momentum grid and provide an isospectral definition of the phase-shift based on the spectral shift of a Chebyshev angle. We address the problem of the unnatural high momentum tails present in the fitted interactions which reaches energies far beyond the maximal center-of-mass energy of $s = 1.4$ GeV. It turns out that these tails can be integrated out by using a block-diagonal generator of the SRG.
↳ hep-phnucl-thActa Phys.Polon.Supp.(2021)·1 citation
08
Semileptonic decays $D \to π^{+} π^{-} e^{+} ν_{e}$ and $D_{s} \to π^{+} π^{-} e^{+} ν_{e}$ as the probe of constituent quark-antiquark pairs in the light scalar mesons
N.N. Achasov🇷🇺 · A.V. Kiselev🇷🇺 · G.N. Shestakov🇷🇺
Decays $D \to π^{+} π^{-} e^{+} ν_{e}$ and $D_{s} \to π^{+} π^{-} e^{+} ν_{e}$ serve as probes that check the existence of constituent $q q ˉ$ components in the wave functions of scalar mesons decaying into $π^{+} π^{-}$ . There exists a great deal of concrete evidence in favor of the exotic four-quark nature of light scalars. At the same time, the further expansion of the area of the $q^{2} q ˉ^{2}$ model validity for light scalars on ever new processes seems extremely interesting and important. We analyze the BESIII and CLEO data on the decays $D^{+} \to π^{+} π^{-} e^{+} ν_{e}$ and $D_{s}^{+} \to π^{+} π^{-} e^{+} ν_{e}$ and show that the results of these experiments together can be interpreted in favor of the four-quark nature of light scalar mesons $σ (500)$ and $f_{0} (980)$ . Our approach can also be applied to the description of other similar decays involving light scalars.
↳ hep-phhep-exnucl-thPRD(2020)·20 citations

Affiliations

first authorsco-authorsvia INSPIRE

Connection between soft and hard probes of small collision systems at RHIC and LHC

On the inversion of isobaric-analogue states in nuclei

Renormalization group and scattering-equivalent Hamiltonians on a coarse momentum grid

Semileptonic decays D→π+π−e+νe​ and Ds​→π+π−e+νe​ as the probe of constituent quark-antiquark pairs in the light scalar mesons

Affiliations

Semileptonic decays $D \to π^{+} π^{-} e^{+} ν_{e}$ and $D_{s} \to π^{+} π^{-} e^{+} ν_{e}$ as the probe of constituent quark-antiquark pairs in the light scalar mesons