Nuclear Theory·nucl-th

Tuesday·October 2, 2018

15 papers—8 primary·7 cross-listed

09
Two-pion contribution to hadronic vacuum polarization
Gilberto Colangelo🇨🇭 · Martin Hoferichter🇺🇸 · Peter Stoffer🇺🇸
We present a detailed analysis of $e^{+} e^{-} \to π^{+} π^{-}$ data up to $s = 1 GeV$ in the framework of dispersion relations. Starting from a family of $π π$ $P$ -wave phase shifts, as derived from a previous Roy-equation analysis of $π π$ scattering, we write down an extended Omnès representation of the pion vector form factor in terms of a few free parameters and study to which extent the modern high-statistics data sets can be described by the resulting fit function that follows from general principles of QCD. We find that statistically acceptable fits do become possible as soon as potential uncertainties in the energy calibration are taken into account, providing a strong cross check on the internal consistency of the data sets, but preferring a mass of the $ω$ meson significantly lower than the current PDG average. In addition to a complete treatment of statistical and systematic errors propagated from the data, we perform a comprehensive analysis of the systematic errors in the dispersive representation and derive the consequences for the two-pion contribution to hadronic vacuum polarization. In a global fit to both time- and space-like data sets we find $a_{μ}^{π π} ∣_{\leq 1 GeV} = 495.0 (1.5) (2.1) \times 1 0^{- 10}$ and $a_{μ}^{π π} ∣_{\leq 0.63 GeV} = 132.8 (0.4) (1.0) \times 1 0^{- 10}$ . While the constraints are thus most stringent for low energies, we obtain uncertainty estimates throughout the whole energy range that should prove valuable in corroborating the corresponding contribution to the anomalous magnetic moment of the muon. As side products, we obtain improved constraints on the $π π$ $P$ -wave, valuable input for future global analyses of low-energy $π π$ scattering, as well as a determination of the pion charge radius, $⟨ r_{π}^{2} ⟩ = 0.429 (1) (4) fm^{2}$ .
↳ hep-phhep-exhep-latnucl-thJHEP(2019)·606 citations
10
High-resolution (p,t) reaction measurements as spectroscopic tests of {\it ab-initio} theory in the mid $p f$ -shell
K.G. Leach · J.D. Holt · P.E. Garrett · S.R. Stroberg · G.C. Ball · P.C. Bender · V. Bildstein · A. Diaz Varela · R. Dunlop · T. Faestermann · B. Hadinia · R. Hertenberger and 9 other authors
Detailed spectroscopic measurements of excited states in $^{50}$ Cr and $^{62}$ Zn were performed using 24~MeV (p,t) transfer reactions on $^{52}$ Cr and $^{64}$ Zn, respectively. In total, forty-five states in $^{50}$ Cr and sixty-seven states in $^{62}$ Zn were observed up to excitation energies of 5.5~MeV, including several previously unobserved states. These experimental results are compared to {\it ab-initio} shell-model calculations using chiral effective field theory ( $χ$ -EFT) with the valence-space in-medium similarity renormalization group (VS-IMSRG) method. This comparison demonstrates good agreement in the level orderings with these new theoretical methods, albeit with a slight over binding in the calculations. This work is part of a continued push to benchmark {\it ab-initio} theoretical techniques to nuclear structure data in $0^{+} \to 0^{+}$ superallowed Fermi $β$ decay systems.
↳ nucl-exnucl-thPRC(2019)·2 citations
11
Quarkonium: a theory overview
Elena G. Ferreiro🇪🇸
Quarkonium has long been proposed as one of the golden probes to identify the phase transition from confined hadronic matter to the deconfined quark-gluon plasma in heavy-ion collisions. Since then, we have achieved a better understanding, not only about the propagation of quarkonium in-medium, but also about its production. Recent theoretical developments in our comprehension of the quarkonium production mechanism in proton-proton collisions and on the propagation of quarkonia in proton-nucleus and nucleus-nucleus collisions are reviewed and discussed.
↳ hep-phnucl-thNPA(2019)·4 citations
12
Hard-core Radius of Nucleons within the Induced Surface Tension Approach
K. A. Bugaev🇺🇦 · A. I. Ivanytskyi🇺🇦 · V. V. Sagun🇺🇦 · B. E. Grinyuk🇺🇦 · D. O. Savchenko🇺🇦 · G. M. Zinovjev🇺🇦 · E. G. Nikonov🇷🇺 · L. V. Bravina🇳🇴 · E. E. Zabrodin🇳🇴 · D. B. Blaschke🇷🇺 · A. V. Taranenko🇷🇺 · L. Turko🇵🇱
In this work we discuss a novel approach to model the hadronic and nuclear matter equations of state using the induced surface tension concept. Since the obtained equations of state, classical and quantum, are among the most successful ones in describing the properties of low density phases of strongly interacting matter, they set strong restrictions on the possible value of the hard-core radius of nucleons. Therefore, we perform a detailed analysis of its value which follows from hadronic and nuclear matter properties and find the most trustworthy range of its values: the hard-core radius of nucleons is 0.30--0.36 fm. A comparison with the phenomenology of neutron stars implies that the hard-core radius of nucleons has to be temperature and density dependent.
↳ hep-phastro-ph.HEnucl-thUniverse(2019)·11 citations
13
First extraction of transversity from data on lepton-hadron scattering and hadronic collisions
Marco Radici🇮🇹
We present the first extraction of the transversity distribution based on the global analysis of pion-pair production in deep-inelastic scattering and in proton-proton collisions with one transversely polarized proton. The extraction relies on the knowledge of di-hadron fragmentation functions, which are taken from the analysis of electron-positron annihilation data. For the first time, the chiral-odd transversity is extracted from a global analysis similar to what is usually done for the chiral-even spin-averaged and helicity distributions. The knowledge of transversity is important among other things for detecting possible signals of new physics in high-precision low-energy experiments.
↳ hep-phhep-exnucl-exnucl-thPoS(2019)·2 citations
14
Constraining New Muonic Interactions Meditated by Axion-Like-Particles
H.Yan🇨🇳 · G.A.Sun🇨🇳 · S.M.Peng🇨🇳 · H.Guo · B.Q.Liu🇨🇳 · M.Peng🇨🇳 · H.Zheng🇨🇳
ALPs (Axion Like Particle) beyond the standard model are solutions to several important problems of modern physics. One way to detect these particles is to detect the new interactions they meditate. Many experiments have been performed to search for these new interactions in ranges from $\sim μ$ m to astrophysical range. At present, nearly all known experiments searching for the ALP-meditated long range new interactions use sources or probes containing protons, neutrons and electrons. Constraints for other fermions such as muons are scarce, though muons might be the most suspicious particles which could take part in new interactions, considering their involvement of several well known puzzles of modern physics. In this work, we discuss the possibility of explaining the anomalous magnetic moment of muons by the long range muonic new interactions mediated by ALPs. We also give a constraint for the scalar-pseudo-scalar(SP) type interaction meditated by muonic ALPs. We propose to further search the muonic SP type interaction by muon spin rotation experiments.
↳ hep-phnucl-exnucl-th0 citations
15
From the colour glass condensate to filamentation: Systematics of classical Yang-Mills theory
Owe Philipsen🇩🇪 · Björn Wagenbach🇩🇪 · Savvas Zafeiropoulos🇩🇪
The non-equilibrium early time evolution of an ultra-relativistic heavy ion collision is often described by classical lattice Yang-Mills theory, starting from the colour glass condensate (CGC) effective theory with an anisotropic energy momentum tensor as initial condition. In this work we investigate the systematics associated with such studies and their dependence on various model parameters (IR, UV cutoffs and the amplitude of quantum fluctuations) which are not yet fixed by experiment. We perform calculations for SU(2) and SU(3), both in a static box and in an expanding geometry. Generally, the dependence on model parameters is found to be much larger than that on technical parameters like the number of colours, boundary conditions or the lattice spacing. In a static box, all setups lead to isotropisation through chromo-Weibel instabilities, which is illustrated by the accompanying filamentation of the energy density. However, the associated time scale depends strongly on the model parameters and in all cases is longer than the phenomenologically expected one. In the expanding system, no isotropisation is observed for any parameter choice. We show how investigations at fixed initial energy density can be used to better constrain some of the model parameters.
↳ hep-lathep-phnucl-thEPJC(2019)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE

Two-pion contribution to hadronic vacuum polarization

High-resolution (p,t) reaction measurements as spectroscopic tests of {\it ab-initio} theory in the mid pf-shell

Quarkonium: a theory overview

Hard-core Radius of Nucleons within the Induced Surface Tension Approach

First extraction of transversity from data on lepton-hadron scattering and hadronic collisions

Constraining New Muonic Interactions Meditated by Axion-Like-Particles

From the colour glass condensate to filamentation: Systematics of classical Yang-Mills theory

Affiliations

High-resolution (p,t) reaction measurements as spectroscopic tests of {\it ab-initio} theory in the mid $p f$ -shell