Nuclear Theory·nucl-th

Friday·January 22, 2021

7 papers—4 primary·3 cross-listed

05
[Submitted on 20 Jan 2021] (cross-list from hep-ph)
On Mass and Matter
Craig D. Roberts🇨🇳
The visible Universe is largely characterised by a single mass-scale; namely, the proton mass, $m_{p}$ . Contemporary theory suggests that $m_{p}$ emerges as a consequence of gluon self-interactions, which are a defining characteristic of quantum chromodynamics (QCD), the theory of strong interactions in the Standard Model. However, the proton is not elementary. Its mass appears as a corollary of other, more basic emergent phenomena latent in the QCD Lagrangian, e.g. generation of nuclear-size gluon and quark mass-scales, and a unique effective charge that may describe QCD interactions at all accessible momentum scales. These remarks are explained herein; and focusing on the distribution amplitudes and functions of $π$ and $K$ mesons, promising paths for their empirical verification are elucidated. Connected therewith, in anticipation that production of $J / ψ$ -mesons using $π$ and $K$ beams can provide access to the gluon distributions in these pseudo-Nambu-Goldstone modes, predictions for all $π$ and $K$ distribution functions are provided at the scale $ζ = m_{J / ψ}$ .
Comments:
10 pages, 7 figures, 3 tables. Commissioned by and to appear as a Feature Article in the Bulletin of the Association of Asia Pacific Physical Societies (AAPPS)
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2101.08340 [pdf]
AAPPS Bull.(2021)·51 citations
06
[Submitted on 21 Jan 2021] (cross-list from hep-ph)
Open charm mesons and Charmonia in magnetized strange hadronic matter
Amal Jahan C.S.🇮🇳 · Amruta Mishra🇮🇳
We investigate the in-medium masses of open charm mesons ( $D$ ( $D^{0}$ , $D^{+}$ ), $D ˉ$ ( $D^{0} ˉ$ , $D^{-}$ ), $D_{s}$ ( $D_{s}^{+}$ , $D_{s}^{-}$ )) and charmonium states ( $J / ψ$ , $ψ (3686)$ , $ψ (3770)$ , $χ_{c 0}$ , $χ_{c 2}$ ) in strongly magnetized isospin asymmetric strange hadronic matter using a chiral effective model. In the presence of the magnetic field, the number density and scalar density of charged baryons have contributions from Landau energy levels. The mass modifications of open charm mesons arise due to their interactions with nucleons, hyperons, and the scalar fields (the non-strange field $σ$ , strange field $ζ$ and isovector field $δ$ ) in the presence of the magnetic field. The mass modifications of the charmonium states arise from the variation of dilaton field ( $χ$ ) in the magnetized medium, which simulates the gluon condensates of QCD. The in-medium mass of open charm mesons and charmonia are observed to decrease with an increase in baryon density, whereas the charged $D^{+}$ , $D^{-}$ , $D_{s}^{+}$ and $D_{s}^{-}$ mesons have additional positive mass shifts due to Landau quantization in the presence of the magnetic field. The effects of strangeness fraction are found to be more dominant for the $D ˉ$ mesons as compared to the $D$ mesons. The mass shifts of charmonia are observed to be larger in hyperonic medium compared to the nuclear medium.
Comments:
35 pages, 8 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2101.08568 [pdf]
CPC(2022)·10 citations
07
[Submitted on 21 Jan 2021] (cross-list from hep-ph)
Photoproduction of $Λ^{*}$ and $Σ^{*}$ resonances with $J^{P} = 1/ 2^{-}$ off the proton
Sang-Ho Kim🇰🇷 · K. P. Khemchandani🇧🇷 · A. Martinez Torres🇧🇷 · Seung-il Nam🇰🇷 · Atsushi Hosaka🇯🇵
We study the photoproduction of the $Λ (1405)$ and $Σ (1400)$ hyperon resonances, the latter of which is not a well established state. We evaluate the $s$ -, $t$ - and $u$ -channel diagrams in the Born approximation by employing the effective Lagrangians. A new ingredient is the inclusion of a nucleon resonance $N^{*} (1895)$ that is dynamically generated with predictions for its coupling to the $K Λ (1405)$ and $K Σ (1400)$ channels. To extend the applicability of the model to energies beyond the threshold region, we consider a Regge model for the $t$ -channel $K$ - and $K^{*}$ -exchanges. Our results are in good agreement with the CLAS data available on $Λ (1405)$ , while for $Σ (1400)$ we predict observables for its production. We also provide polarization observables for both hyperon productions, which can be useful in future experimental investigations. The present study provides new information on the nucleon resonance $N^{*} (1895)$ which can be an alternative source for generating the hyperon resonances $Λ (1405)$ and $Σ (1400)$ .
Comments:
13 pages, 9 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2101.08668 [pdf]
PRD(2021)·24 citations

Affiliations

first authorsco-authorsvia INSPIRE

On Mass and Matter

Open charm mesons and Charmonia in magnetized strange hadronic matter

Photoproduction of Λ∗ and Σ∗ resonances with JP=1/2− off the proton

Affiliations

Photoproduction of $Λ^{}$ and $Σ^{}$ resonances with $J^{P} = 1/ 2^{-}$ off the proton