Nuclear Theory·nucl-th

Monday·April 1, 2019

8 papers—3 primary·5 cross-listed

04
[Submitted on 28 Mar 2019] (cross-list from hep-ph)
QED radiative corrections for Polarized Lepton-Proton Scattering
Razvan-Daniel Bucoveanu🇩🇪 · Hubert Spiesberger🇩🇪
We discuss QED radiative corrections at first and second order for the parity violating asymmetry $A_{PV}$ in elastic electron proton scattering. A measurement of $A_{PV}$ is planned at low energies and with high precision by the forthcoming P2 experiment at the new MESA facility in Mainz. Bremsstrahlung leads to a shift of the momentum transfer $Q^{2}$ which affects the determination of the weak charge of the proton.
Comments:
6 pages, 5 figures, submitted to SPIN2018 Conference Proceedings
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1903.12229 [pdf]
PoS(2019)·5 citations
05
[Submitted on 28 Mar 2019] (cross-list from hep-ph)
Theoretical study on \eta'--> 4 pions
Ehsan Jafari🇺🇸 · Bing An Li🇺🇸
The $η^{'}$ meson is associated with the U(1) anomaly. In this paper, a successful effective chiral theory of mesons has been applied to study the anomalous decay of $η^{'} \to π^{+} π^{-} π^{+ (0)} π^{- (0)}$ . In this study, the contributions of triangle and box anomalies are calculated. It is shown that the contribution of box diagrams is important in this process. We predict branching ratios of $B r (η^{'} \to π^{+} π^{-} π^{+} π^{-}) = \frac{1}{2} B r (η^{'} \to π^{+} π^{-} π^{0} π^{0}) = (8.3 \pm 1.2) \times 1 0^{- 5}$ , which is in good agreement with BESIII measurement.
Comments:
12 pages, 1 figure, 1 table
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1903.12275 [pdf]
NPB(2021)·0 citations
06
[Submitted on 29 Mar 2019] (cross-list from hep-ph)
Renormalization of Unitarized Weinberg-Tomozawa Interaction without On-shell Factorization and $I = 0$ $K ˉ N$ - $π Σ$ Coupled Channels
Osamu Morimatsu🇯🇵 · Kazuki Yamada🇯🇵
We calculate the scattering $T$ -matrix of $I = 0$ $K ˉ N - π Σ$ coupled channels taking a ladder sum of the Weinberg-Tomozawa interaction without on-shell factorization, regularizing three types of divergent meson-baryon loop functions by dimensional regularization and renormalizing them by introducing counter terms. We show that not only infinite but also finite renormalization is important in order for the renormalized physical scattering $T$ -matrix to have the form of the Weinberg-Tomozawa interaction. The results with and without on-shell factorization are compared. The difference of the scattering $T$ -matrix is small near the renormalization point, close to the observed $Λ$ (1405). The difference, however, increases with the distance from the renormalization point. The scattering $T$ -matrix without on-shell factorization has two poles in the complex center-of-mass energy plane as with on-shell factorization, the real part of which is close to the observed $Λ$ (1405). While the difference is small with and without on-shell factorization in the position of the first pole, closer to the observed $Λ$ (1405), the difference is considerably large in the position of the second pole: the imaginary part of the center-of-mass energy of the second pole without on-shell factorization is as large as or even larger than twice that with on-shell factorization. Also, we discuss the origin of the contradiction about the second pole between two approaches, the chiral unitary approach with on-shell factorization and the phenomenological approach without on-shell factorization.
Comments:
19 pages, 7 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1903.12380 [pdf]
PRC(2019)·12 citations
07
[Submitted on 29 Mar 2019] (cross-list from nucl-ex)
Searching for flavor dependence in nuclear quark behavior
J. Arrington🇺🇸 · N. Fomin🇺🇸
The observed correlation between the EMC effect and the contribution of short-range correlations (SRCs) in nuclei suggests that the modification of the quark distributions of bound protons and neutrons might occur within SRCs. This raises the possibility that the EMC effect may have an isospin dependence arising from the np dominance of SRCs. We discuss previous attempts to test this possibility and perform a new analysis of existing data. We find no experimental support for the observation of an isospin dependence of the EMC effect.
Comments:
5 pages, 4 figures, submitted for publication
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1903.12535 [pdf]
PRL(2019)·27 citations
08
[Submitted on 29 Mar 2019] (cross-list from nucl-ex)
High Density with Elliptic Flows
W. Trautmann
The elliptic flow of emitted particles and fragments observed in heavy-ion reactions at high energy has become an important observable reflecting the pressure generated in the dense collision zone. More recently, the strength of the nuclear symmetry energy has been investigated by measuring the ratios or differences of the elliptic flows exhibited by neutrons and charged particles in 197Au+197Au collisions at 400 MeV/nucleon incident energy at the GSI laboratory. A moderately soft to linear dependence on density was deduced for a range of densities shown to reach beyond twice the saturation value in these experiments. The known sources of uncertainties and possible model dependencies were thoroughly studied with transport models of the UrQMD and Tuebingen QMD type. A new source of information on the nuclear equation of state at high density has opened up with the observation of the first LIGO and Virgo GW170817 gravitational wave signal from a neutron star merger. The quantitative comparison of terrestrial and celestial results on the basis of measured or inferred neutron star radii or core pressures, including those obtained from X-ray observations, reveals a rather satisfactory agreement. Depending on the precision that can be achieved with future measurements and observations, it will thus become possible to assess the validity of the applied models and methods. The perspectives for improved experiments at FAIR using the NeuLAND and KRAB detection systems are outlined.
Comments:
15 pages, 10 figures, to appear in the AIP Conference Proceedings of the Xiamen-CUSTIPEN Workshop on the EOS of Dense Neutron-Rich Matter in the Era of Gravitational Wave Astronomy (January 3 - 7, 2019, Xiamen, China)
Subjects:
Nuclear Experiment (nucl-ex); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1903.12543 [pdf]
AIP Conf.Proc.(2019)·11 citations

Affiliations

first authorsco-authorsvia INSPIRE

QED radiative corrections for Polarized Lepton-Proton Scattering

Theoretical study on \eta'--> 4 pions

Renormalization of Unitarized Weinberg-Tomozawa Interaction without On-shell Factorization and I=0 KˉN - πΣ Coupled Channels

Searching for flavor dependence in nuclear quark behavior

High Density with Elliptic Flows

Affiliations

Renormalization of Unitarized Weinberg-Tomozawa Interaction without On-shell Factorization and $I = 0$ $K ˉ N$ - $π Σ$ Coupled Channels