Proton number fluctuations in $\sqrt{s_{NN}}$ = 2.4 GeV Au+Au collisions studied with HADES
J. Adamczewski-Musch, O. Arnold, C. Behnke, A. Belounnas, A. Belyaev, J. C. Berger-Chen, J. Biernat, A. Blanco, C. Blume, M. B"ohmer, P. Bordalo, S. Chernenko, … 展开作者
J. Adamczewski-Musch, O. Arnold, C. Behnke, A. Belounnas, A. Belyaev, J. C. Berger-Chen, J. Biernat, A. Blanco, C. Blume, M. B"ohmer, P. Bordalo, S. Chernenko, L. Chlad, C. Deveaux, J. Dreyer, A. Dybczak, E. Epple, L. Fabbietti, O. Fateev, P. Filip, P. Fonte, C. Franco, J. Friese, I. Fr"ohlich, T. Galatyuk, J. A. Garzon, R. Gernh"auser, M. Golubeva, R. Greifenhagen, F. Guber, M. Gumberidze, S. Harabasz, T. Heinz, T. Hennino, S. Hlavac, C. H"ohne, R. Holzmann, A. Ierusalimov, A. Ivashkin, B. K"ampfer, T. Karavicheva, B. Kardan, I. Koenig, W. Koenig, M. Kohls, B. W. Kolb, G. Korcyl, G. Kornakov, F. Kornas, R. Kotte, A. Kugler, T. Kunz, A. Kurepin, A. Kurilkin, P. Kurilkin, V. Ladygin, R. Lalik, K. Lapidus, A. Lebedev, L. Lopes, M. Lorenz, T. Mahmoud, L. Maier, A. Mangiarotti, J. Markert, T. Matulewicz, S. Maurus, V. Metag, J. Michel, D. M. Mihaylov, S. Morozov, C. M"untz, R. M"unzer, L. Naumann, K. Nowakowski, M. Palka, Y. Parpottas, V. Pechenov, O. Pechenova, O. Petukhov, K. Piasecki, J. Pietraszko, W. Przygoda, S. Ramos, B. Ramstein, A. Reshetin, P. Rodriguez-Ramos, P. Rosier, A. Rost, A. Rustamov, A. Sadovsky, P. Salabura, T. Scheib, H. Schuldes, E. Schwab, F. Scozzi, F. Seck, P. Sellheim, I. Selyuzhenkov, J. Siebenson, L. Silva, Yu. G. Sobolev, S. Spataro, S. Spies, H. Str"obele, J. Stroth, P. Strzempek, C. Sturm, O. Svoboda, M. Szala, P. Tlusty, M. Traxler, H. Tsertos, E. Usenko, V. Wagner, C. Wendisch, M. G. Wiebusch, J. Wirth, Y. Zanevsky, P. Zumbruch
We present an analysis of proton number fluctuations in $\sqrt{s_{NN}}$ = 2.4 GeV Au+Au collisions measured with the High-Acceptance DiElectron Spectrometer (HADES) at GSI. With the help of extensive detector simulations done with IQMD transport model events including nuclear clusters, various nuisance effects influencing the observed proton cumulants have been investigated. Acceptance and efficiency corrections have been applied as a function of fine grained rapidity and transverse momentum bins, as well as considering local track density dependencies. Next, the effects of volume changes within particular centrality selections have been considered and beyond-leading-order corrections have been applied to the data. The efficiency and volume corrected proton number moments and cumulants Kn of orders n = 1, . . . , 4 have been obtained as a function of centrality and phase-space bin, as well as the corresponding correlators C_n . We find that the observed correlators show a power-law scaling with the mean number of protons, i.e. $C_n \propto <N>^n$, indicative of mostly long-range multi-particle correlations in momentum space. We also present a comparison of our results with Au+Au collision data obtained at RHIC at similar centralities, but higher $\sqrt{s_{NN}}$.
Within a transport model coupled with a microscopic coalescence model, the directed and elliptic flows of protons and deuterons as well as their scalling properties are studied in the centrality of 20-30% Au+Au collisions at $\sqrt{s_{\rm NN}}=2.4$ GeV. It is found that the flows as well as their scaling properties simulated with the isospin- and momentum-dependent nuclear mean field with an incompressibility $K_{0}=230$ MeV fit fairly the HADES data, while those simulated with the commonly used momentum-independent nuclear mean field with an incompressibility $K_{0}=380$ MeV can only fit part…
Study of exclusive one-pion and one-eta production using hadron and dielectron channels in pp reactions at kinetic beam energies of 1.25 GeV and 2.2 GeV with HADES
We investigate the coalescence factors $B_2$ and $B_3$ at low collision energies ($\sqrt{s_\mathrm{NN}}<6$ GeV) with special focus on the HADES and RHIC-BES experiments. It is shown that, in order to properly interpret the coalescence factors $B_A$, two important corrections are necessary: I) $B_2$ has to be calculated using the proton $\times$ neutron yields in the denominator, instead of the square of the proton yield, and II) the primordial proton (neutron) densities have to be used for the normalization and not the final state (free) protons (neutrons). Both effects lead to a drastic reduc…
Centrality dependence of the directed flow of protons in Au+Au collisions at the beam energy of 1.23A GeV collected by the HADES experiment at GSI is presented. Measurements are performed with respect to the spectators plane estimated using the Forward Wall hodoscope. Biases due to non-flow correlations and correlated detector effects are evaluated. The corresponding systematic uncertainties are quantified using estimates of the spectators plane from various forward rapidity regions constructed from groups of Forward Wall channels and protons reconstructed with the HADES tracking system.
Measurement of Differential Cross Sections and Integrated Luminosity using Proton-Proton Elastic Scattering with HADES at T = 4.53 GeV and T = 1.60 GeV
We used an Isospin dependent Quantum Molecular Dynamics (IQMD) model to simulate Au + Au collisions at beam energy $E_{beam}$ = 1.23$A$ GeV, which corresponds to center of mass energy $\sqrt{s_{NN}} = 2.4$ GeV. Firstly, we obtained reasonable rapidity and transverse mass spectra of $π^-$ and $π^+$ as well as "apparent" temperature parameters in comparison with the HADES data. Then by calculating three-dimensional Hanbury Brown and Twiss (HBT) radius of same charged pion-pairs, we obtained the square difference of outward radius and sideward radius, i.e. $R_{out}^{2}-R_{side}^{2}$, as well as t…
Production of $e^{+}e^{-}$ from U+U collisions at $\sqrt{s_{NN}}$ = 193 GeV and Au+Au collisions at $\sqrt{s_{NN}}$ = 19.6, 27, 39, 62.4, and 200 GeV as measured by STAR
The HADES experiment at GSI has recently provided data on the flow coefficients $v_1,...,v_4$ for protons in Au+Au reactions at $E_{\rm lab} = 1.23$~$A$GeV (or $\sqrt{s_\mathrm{NN}}=2.4$ GeV). This data allows to estimate the shear viscosity over entropy ratio, $η/s$ at low energies via a coarse graining analysis of the UrQMD transport simulations of the flow harmonics in comparison to the experimental data. By this we can provide for the first time an estimate of $η/s\approx0.65\pm0.15$ (or $(8\pm2)\,(4π)^{-1}$) at such low energies.
The double differential production cross sections, $d^2σ/dΩdE$, for hydrogen isotopes and charged pions in the reaction of p + Nb at 3.5 GeV proton beam energy have been measured by the High Acceptance DiElectron Spectrometer (HADES). Thanks to the high acceptance of HADES at forward emission angles and usage of its magnetic field, the measured energy range of hydrogen isotopes could be significantly extended in comparison to the relatively scarce experimental data available in the literature. The data provide information about the development of the intranuclear cascade in the proton-nucleus …
Measurements of Non-photonic Electron Production and Azimuthal Anisotropy in $\sqrt {s_{NN}} = 39$, 62.4 and 200 GeV \auau\ Collisions from STAR at RHIC
The measurement of J/{psi} azimuthal anisotropy is presented as a function of transverse momentum for different centralities in Au+Au collisions at {sqrt{s_{NN}}} = 200 GeV. The measured J/{psi} elliptic flow is consistent with zero within errors for transverse momentum between 2 and 10 GeV/c. Our measurement suggests that J/{psi} with relatively large transverse momentum are not dominantly produced by coalescence from thermalized charm quarks, when comparing to model calculations.
We compute the $Λ$ and $\overlineΛ$ global polarizations in semi-central heavy-ion collisions using the core-corona model where the source of $Λ$'s and $\overlineΛ$'s is taken as consisting of a high-density core and a less dense corona. We show that the overall properties of the polarization excitation functions can be linked to the relative abundance of $Λ$s coming from the core versus those coming from the corona. For low collision energies, the former are more abundant whereas for higher energies the latter become more abundant. The main consequence of this reversing of the relative abunda…
