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

Azimuthal anisotropy of charged jet production in sNN\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 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

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

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

Anisotropic flow of identified particles in Pb--Pb collisions at sNN=5.02\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

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

Thermal evolution and structure models of the transiting super-Earth GJ 1214b

The planet GJ 1214b is the second known super-Earth with a measured mass and radius. Orbiting a quiet M-star, it receives considerably less mass-loss driving X-ray and UV radiation than CoRoT-7b, so that the interior may be quite dissimilar in composition, including the possibility of a large fraction of water. We model the interior of GJ 1214b assuming a two-layer (envelope+rock core) structure where the envelope material is either H/He, pure water, or a mixture of H/He and H2O. Within this framework we perform models of the thermal evolution and contraction of the planet. We discuss possible compositions that are consistent with Mp=6.55 ME, Rp=2.678 RE, an age tau=3-10 Gyr, and the irradiation level of the atmosphere. These conditions require that if water exists in the interior, it must remain in a fluid state, with important consequences for magnetic field generation. These conditions also require the atmosphere to have a deep isothermal region extending down to 80-800 bar, depending on composition. Our results bolster the suggestion of a metal-enriched H/He atmosphere for the planet, as we find water-world models that lack an H/He atmosphere to require an implausibly large water-to-rock ratio of more than 6:1. We instead favor a H/He/H2O envelope with high water mass fraction (~0.5-0.85), similar to recent models of the deep envelope of Uranus and Neptune. Even with these high water mass fractions in the H/He envelope, generally the bulk composition of the planet can have subsolar water:rock ratios. Dry, water-enriched, and pure water envelope models differ to an observationally significant level in their tidal Love numbers k2 of respectively ~0.018, 0.15, and 0.7.Comment: 11 pages, 6 figures, 1 table, accepted to Ap