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Search Results: 1 - 10 of 1714 matches for " Vogel Sascha "
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Photon Signals from Quarkyonic Matter
Torrieri, Giorgio;Vogel, Sascha
High Energy Physics - Phenomenology , 2013,
Abstract: We calculate the Bremsstrahlung photon spectrum emitted from dynamically evolving quarkyonic matter, and compare this spectrum with that of a high chemical potential quark-gluon plasma. We find that while the rapidity distributions are similar, the transverse momentum distribution and the harmonic coefficient is markedly different in the two cases. The transverse momentum distribution can be fit with an exponential, but is markedly steeper than the distribution expected for the quark-gluon plasma, even at the lower temperatures expected in the critical point region. The $v_2$ coefficient fluctuates chaotically from event to event, and even within the same event at different transverse momenta. The latter effect, which can be explained by the shape of quark wave functions within quarkyonic matter, might be considered as a quarkyonic matter signature.
Why the $a_1$ meson might be a difficult messenger for the restoration of chiral symmetry
Vogel, Sascha;Bleicher, Marcus
High Energy Physics - Phenomenology , 2007, DOI: 10.1103/PhysRevC.78.064910
Abstract: We perform a theoretical analysis of the $a_1$ resonance mass spectrum in ultra-relativistic heavy ion collisions within a hadron/string transport approach. Predictions for the $a_1$ yield and its mass distribution are given for the GSI-FAIR and the critRHIC energy regime. The potential of the $a_1$ meson as a signal for chiral symmetry restoration is explored. In view of the latest discussion, we investigate the decay channel $a_1 \to \gamma\pi$ in detail and find a strong bias towards low $a_1$ masses. This apparent mass shift of the $a_1$ if observed in the $\gamma\pi$ channel might render a possible mass shift due to chiral symmetry restoration very difficult to disentangle from the decay kinematics.
Resonance studies with the UrQMD model
Vogel Sascha,Bleicher Marcus
EPJ Web of Conferences , 2012, DOI: 10.1051/epjconf/20123600019
Abstract: These proceedings will cover various studies of hadronic resonances within the UrQMD transport model. After a brief explanation of the model, various observables will be highlighted and the chances for resonance reconstruction in hadronic channels will be discussed. Possible signals of chiral symmetry restoration will be investigated for feasibility.
Resonance Absorption and Regeneration in Relativistic Heavy Ion Collisions
Sascha Vogel,Marcus Bleicher
Physics , 2005,
Abstract: The regeneration of hadronic resonances is discussed for heavy ion collisions at SPS and SIS-300 energies. The time evolutions of Delta, rho and phi resonances are investigated. Special emphasize is put on resonance regeneration after chemical freeze-out. The emission time spectra of experimentally detectable resonances are explored.
Some Considerations concerning the Fluctuation of the Ratios of two Observables
Michael Hauer,Sascha Vogel
Physics , 2010, DOI: 10.1103/PhysRevC.83.064906
Abstract: We discuss several possible caveats which arise with the interpretation of measurements of fluctuations in heavy ion collisions. We especially focus on the ratios of particle yields, which has been advocated as a possible signature of a critical point in the QCD phase diagram. We conclude that current experimental observables are not well-defined and are without a proper quantitative meaning.
Reconstructing $ρ^0$ and $ω$ mesons from non-leptonic decays in C+C at 2AGeV
Sascha Vogel,Marcus Bleicher
Physics , 2005, DOI: 10.1103/PhysRevC.74.014902
Abstract: We predict transverse and longitudinal momentum spectra and yields of $\rho^0$ and $\omega$ mesons reconstructed from hadron correlations in C+C reactions at 2~AGeV. The rapidity and $p_T$ distributions for reconstructable $\rho^0$ mesons differs strongly from the primary distribution, while the $\omega$'s distributions are only weakly modified. We discuss the temporal and spatial distributions of the particles emitted in the hadron channel. Finally, we report on the mass shift of the $\rho^0$ due to its coupling to the $N^*(1520)$, which is observable in both the di-lepton and $\pi\pi$ channel. Our calculations can be tested with the Hades experiment at GSI, Darmstadt.
Elliptic flow fluctuations in heavy ion collisions at RHIC and the perfect fluid hypothesis
Vogel, Sascha;Torrieri, Giorgio;Bleicher, Marcus
High Energy Physics - Phenomenology , 2007,
Abstract: We analyse the recently measured $v_2$ fluctuation in the context of establishing the degree of fluidity of the matter produced in heavy ion collisions. We argue that flow observables within systems with a non-negligible mean free path should acquire a "dynamical" fluctuation, due to the random nature of each collision between the system's degrees of freedom. Because of this, $v_2$ fluctuations can be used to estimate the Knudsen number of the system produced at RHIC. To illustrate this quantitatively, we apply the UrQMD model, with scaled cross sections, to show that collisions at RHIC have a Knudsen number at least one order of magnitude above the expected value for an interacting hadron gas. Furthermore, we argue that the Knudsen number is also bound from above by the $v_2$ fluctuation data, because too large a Knudsen number would break the observed scaling of $v_2$ fluctuations due to the onset of turbulent flow. We propose, therefore that $v_2$ fluctuation measurements, together with an understanding of the turbulent regime for relativistic hydrodynamics, will provide an upper as well as a lower limit for the Knudsen number.
Resonances as a possible observable of hot and dense nuclear matter
Sascha Vogel,Joerg Aichelin,Marcus Bleicher
Physics , 2010, DOI: 10.1088/0954-3899/37/9/094046
Abstract: One of the most fundamental questions in the field of relativistic heavy ion physics is how to reach and explore densities which are needed to cross the chiral and/or the deconfinement phase transition. In this analysis we investigate the information we can gather by analyzing baryonic and mesonic resonances on the hot and dense phase in such nuclear reactions. The decay products of these resonances carry information on the resonances properties at the space time point of their decay. We especially investigate the percentage of reconstructable resonances as a function of density for heavy ion collisions in the energy range between $E_{lab}$ = 30 AGeV and $\sqrt{s}$ = 200 AGeV, the energy domain between the future FAIR facility and the present RHIC collider.
Photon Signals from Quarkyonic Matter
Giorgio Torrieri,Sascha Vogel,Bjoern Baeuchle
Physics , 2013, DOI: 10.1103/PhysRevLett.111.012301
Abstract: We calculate the Bremsstrahlung photon spectrum emitted from dynamically evolving quarkyonic matter, and compare this spectrum with that of a high chemical potential quark-gluon plasma as well as to a hadron gas. We find that the transverse momentum distribution and the harmonic coefficient is markedly different in the three cases. The transverse momentum distribution of quarkyonic matter can be fit with an exponential, but is markedly steeper than the distribution expected for the quark-gluon plasma or a hadron gas, even at the lower temperatures expected in the critical point region. The quarkyonic elliptic flow coefficient fluctuates randomly from event to event, and within the same event at different transverse momenta. The latter effect, which can be explained by the shape of quark wavefunctions within quarkyonic matter, might be considered as a quarkyonic matter signature, provided initial temperature is low enough that the quarkyonic regime dominates over deconfinement effects, and the reaction-plane flow can be separated from the fluctuating component.
Elliptic flow fluctuations in heavy ion collisions at RHIC and the perfect fluid hypothesis
Sascha Vogel,Giorgio Torrieri,Marcus Bleicher
Physics , 2007, DOI: 10.1103/PhysRevC.82.024908
Abstract: We analyse the recently measured $v_2$ fluctuation in the context of establishing the degree of fluidity of the matter produced in heavy ion collisions. We argue that flow observables within systems with a non-negligible mean free path should acquire a "dynamical" fluctuation, due to the random nature of each collision between the system's degrees of freedom. Because of this, $v_2$ fluctuations can be used to estimate the Knudsen number of the system produced at RHIC. To illustrate this quantitatively, we apply the UrQMD model, with scaled cross sections, to show that collisions at RHIC have a Knudsen number at least one order of magnitude above the expected value for an interacting hadron gas. Furthermore, we argue that the Knudsen number is also bound from above by the $v_2$ fluctuation data, because too large a Knudsen number would break the observed scaling of $v_2$ fluctuations due to the onset of turbulent flow. We propose, therefore that $v_2$ fluctuation measurements, together with an understanding of the turbulent regime for relativistic hydrodynamics, will provide an upper as well as a lower limit for the Knudsen number.
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