2,638 research outputs found

### Measurement of meson transition form factors at BESIII

Meson transition form factors describe the coupling of photons and hadrons.
They are an important input to the calculations of the light-by-light
scattering contribution of the anomalous magnetic moment of the muon. At the
BESIII experiment in Beijing, the transition form factors of pseudoscalar
mesons are studied in their Dalitz decays, in their radiative production in
$e^+e^-$ annihilation, and in their production in two-photon scattering. All
relevant kinematic regimes are covered. An overview of the recent results and
the status of the ongoing analyses is provided.Comment: Talk presented CIPANP2018. 9 pages, LaTeX, 4 pdf figure

### Anisotropic flow of identified particles in Pb--Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV

Anisotropic flow is sensitive to the shear $(\eta/s)$ and bulk ($\zeta/s$)
viscosity of the quark-gluon plasma created in heavy-ion collisions, as well as
the initial state of such collisions and hadronization mechanisms. In these
proceedings, elliptic ($v_2$) and higher harmonic ($v_3, v_4$) flow
coefficients of $\pi^{\pm}$, $K^{\pm}$, p$(\overline{\rm{p}})$ and the
$\phi$-meson, are presented for Pb-Pb collisions at the highest-ever
center-of-mass energy of $\sqrt{s_{\rm NN}}$ = 5.02 TeV. Comparisons to
hydrodynamic calculations (IP-Glasma, MUSIC, UrQMD) are shown to constrain the
initial conditions and viscosity of the medium

### Azimuthal anisotropy of charged jet production in $\mathbf{\sqrt{{\textit s}_{\rm NN}}}$ = 2.76 TeV Pb--Pb collisions

Measurements of charged jet production with respect to the second-order
harmonic event plane, quantified as $v_{2}^{\mathrm{ch~jet}}$, in
$\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV Pb--Pb collisions are presented. The
contribution of hydrodynamic flow to the underlying event energy is corrected
for on a jet-by-jet basis. Remaining effects from instrumental resolution and
regional fluctuations in the energy density of the underlying event are
corrected for by unfolding. Significant $v_{2}^{\mathrm{ch~jet}}$ is observed
in semi-central collisions. Qualitative agreement is found with
$v_{2}^{\mathrm{ch+em jet}}$ of jets reconstructed from charged and neutral
fragments and $v_2$ of single charged particles, as well as with predictions
from the JEWEL Monte Carlo model.Comment: 4 pages, 5 figures, to appear in the proceedings of Quark Matter
2015, KOBE, Japa

### Measurement of Hadronic Cross Sections at BESIII

The uncertainties of the Standard Model prediction of the anomalous magnetic
moment of the muon are currently completely dominated by hadronic
contributions. The largest contribution is due to the hadronic vacuum
polarization. Hadronic cross sections measured at $e^+e^-$ colliders can be
exploited as experimental input to improve the calculations, making use of the
optical theorem. At the BESIII experiment in Beijing these cross sections are
determined using different methods. At center-of-mass energies above 2 GeV
exclusive and inclusive cross sections can be measured in an energy scan.
Additionally, cross sections can be determined starting from the $\pi^+\pi^-$
mass threshold using the method of Initial State Radiation. An overview of the
recent results and the status of the analyses is provided.Comment: Talk presented CIPANP2018. 10 pages, LaTeX, 7 pdf figure

### Thermophysical properties of warm dense hydrogen

We study the thermophysical properties of warm dense hydrogen using quantum
molecular dynamics simulations. New results are presented for the pair
distribution functions, the equation of state, the Hugoniot curve, and the
reflectivity. We compare with available experimental data and predictions of
the chemical picture. Especially, we discuss the nonmetal-to-metal transition
which occurs at about 40 GPa in the dense fluid

### Interpolation formula for the electrical conductivity of nonideal plasmas

On the basis of a quantum-statistical approach to the electrical conductivity
of nonideal plasmas we derive analytical results in the classical low-density
regime, in the degenerate Born limit, and for the contribution of the
Debye-Onsager relaxation effect. These explicit results are used to construct
an improved interpolation formula of the electrical conductivity valid in a
wide range of temperature and density which allows to compare with available
experimental data of nonideal plasmas.Comment: 7 pages, 1 tabl

### Proceedings of the International PrimeNet Workshop

These are the proceedings of the PrimeNet Workshop, held in September 16-18,
2010, at the campus of Instituto Superior T\'ecnico in Lisbon, Portugal. This
workshop is part of the activities in the project "Study of Strongly
Interacting Matter" (acronym HadronPhysics2), which is an integrating activity
of the Seventh Framework Program of EU. This HP2 project contains several
activities, one of them being the network PrimeNet having the focus on Meson
Physics in Low-Energy QCD. This network is created to exchange information on
experimental and theoretical ongoing activities on mainly eta and eta-prime
physics at different European accelerator facilities and institutes.Comment: 78 pages; Each talk is represented by an extended abstrac

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