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H. Stoecker
GSI Helmholtzzentrum für Schwerionenforschung GmbH, D-64291 Darmstadt, Germany

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Conference report
Published: 02 February 2021 in Particles
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In this talk we presented a novel technique, based on Deep Learning, to determine the impact parameter of nuclear collisions at the CBM experiment. PointNet based Deep Learning models are trained on UrQMD followed by CBMRoot simulations of Au+Au collisions at 10 AGeV to reconstruct the impact parameter of collisions from raw experimental data such as hits of the particles in the detector planes, tracks reconstructed from the hits or their combinations. The PointNet models can perform fast, accurate, event-by-event impact parameter determination in heavy ion collision experiments. They are shown to outperform a simple model which maps the track multiplicity to the impact parameter. While conventional methods for centrality classification merely provide an expected impact parameter distribution for a given centrality class, the PointNet models predict the impact parameter from 2–14 fm on an event-by-event basis with a mean error of −0.33 to 0.22 fm.

ACS Style

Manjunath Kuttan; Jan Steinheimer; Kai Zhou; Andreas Redelbach; Horst Stoecker. Deep Learning Based Impact Parameter Determination for the CBM Experiment. Particles 2021, 4, 47 -52.

AMA Style

Manjunath Kuttan, Jan Steinheimer, Kai Zhou, Andreas Redelbach, Horst Stoecker. Deep Learning Based Impact Parameter Determination for the CBM Experiment. Particles. 2021; 4 (1):47-52.

Chicago/Turabian Style

Manjunath Kuttan; Jan Steinheimer; Kai Zhou; Andreas Redelbach; Horst Stoecker. 2021. "Deep Learning Based Impact Parameter Determination for the CBM Experiment." Particles 4, no. 1: 47-52.

Journal article
Published: 06 March 2020 in Energies
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In power systems, flow allocation (FA) methods enable to allocate the usage and costs of the transmission grid to each single market participant. Based on predefined assumptions, the power flow is split into isolated generator-specific or producer-specific sub-flows. Two prominent FA methods, Marginal Participation (MP) and Equivalent Bilateral Exchanges (EBEs), build upon the linearized power flow and thus on the Power Transfer Distribution Factors (PTDFs). Despite their intuitive and computationally efficient concepts, they are restricted to networks with passive transmission elements only. As soon as a significant number of controllable transmission elements, such as high-voltage direct current (HVDC) lines, operate in the system, they lose their applicability. This work reformulates the two methods in terms of Virtual Injection Patterns (VIPs), which allows one to efficiently introduce a shift parameter q to tune contributions of net sources and net sinks in the network. In this work, major properties and differences in the methods are pointed out, and it is shown how the MP and EBE algorithms can be applied to generic meshed AC-DC electricity grids: by introducing a pseudo-impedance ω¯, which reflects the operational state of controllable elements and allows one to extend the PTDF matrix under the assumption of knowing the current flow in the system. Basic properties from graph theory are used to solve for the pseudo-impedance in dependence of the position within the network. This directly enables, e.g., HVDC lines to be considered in the MP and EBE algorithms. The extended methods are applied to a low-carbon European network model (PyPSA-EUR) with a spatial resolution of 181 nodes and an 18% transmission expansion compared to today’s total transmission capacity volume. The allocations of MP and EBE show that countries with high wind potentials profit most from the transmission grid expansion. Based on the average usage of transmission system expansion, a method of distributing operational and capital expenditures is proposed. In addition, it is shown how injections from renewable resources strongly drive country-to-country allocations and thus cross-border electricity flows.

ACS Style

Fabian Hofmann; Markus Schlott; Alexander Kies; Horst Stöcker. Flow Allocation in Meshed AC-DC Electricity Grids. Energies 2020, 13, 1233 .

AMA Style

Fabian Hofmann, Markus Schlott, Alexander Kies, Horst Stöcker. Flow Allocation in Meshed AC-DC Electricity Grids. Energies. 2020; 13 (5):1233.

Chicago/Turabian Style

Fabian Hofmann; Markus Schlott; Alexander Kies; Horst Stöcker. 2020. "Flow Allocation in Meshed AC-DC Electricity Grids." Energies 13, no. 5: 1233.

Preprint
Published: 29 January 2020
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In power systems, flow allocation (FA) methods allow to allocate usage and costs of the transmission grid to each single market participant. Based on predefined assumptions, the power flow is split into isolated generator specific or producer specific sub-flows. Two prominent FA methods, Marginal Participation (MP) and Equivalent Bilateral Exchanges (EBE), build upon the linearized power flow and thus on the Power Transfer Distribution Factors (PTDF). Despite their intuitive and computationally efficient concept, they are restricted to networks with \emph{passive} transmission elements only. As soon as a significant number of \emph{controllable} transmission elements, such as High-voltage direct current (HVDC) lines, operate in the system, they loose their applicability. This work reformulates the two methods in terms of Virtual Injection Patters (VIP) which allows to efficiently introduce a shift parameter $q$, tuning contributions of net sources and net sinks in the network. Major properties and differences of the methods are pointed out. Finally, it is shown how the MA and EBE algorithm can be applied to generic meshed AC-DC electricity grids: Introducing a \emph{pseudo-impedance} which reflects the operational state of controllable elements, allows to extend the PTDF matrix under the assumption of knowing the current system's flow. Basic properties from graph theory are used for solving the pseudo-impedance dependent on the position in the network. This directly enables \emph{e.g.} HVDC lines to be considered in the MP and EBE algorithm. The extended methods are applied to a low-carbon European network model (PyPSA-EUR) with a spatial resolution of N=181 and an 18\% transmission expansion. The allocations of VIP and MP, show that countries with high wind potentials profit most from the transmission grid expansion. Based on the average usage of transmission system expansion a method of distributing operational and capital expenditures is proposed. Further it is shown, how injections from renewable resources strongly drive country-to-country allocations and thus cross-border electricity flows.

ACS Style

Fabian Hofmann; Markus Schlott; Alexander Kies; Horst Stöcker. Flow Allocation in Meshed AC-DC Electricity Grids. 2020, 1 .

AMA Style

Fabian Hofmann, Markus Schlott, Alexander Kies, Horst Stöcker. Flow Allocation in Meshed AC-DC Electricity Grids. . 2020; ():1.

Chicago/Turabian Style

Fabian Hofmann; Markus Schlott; Alexander Kies; Horst Stöcker. 2020. "Flow Allocation in Meshed AC-DC Electricity Grids." , no. : 1.

Article
Published: 13 August 2019 in Physical Review D
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A model of inflation realization driven by fermions with curvature-dependent mass is studied. Such a term is derived from the covariant canonical gauge theory of gravity (CCGG) incorporating Dirac fermions. We obtain an initial de Sitter phase followed by a successful exit, and moreover we acquire the subsequent thermal history, with an effective matter era, followed finally by a dark-energy epoch. This behavior is a result of the effective “weakening” of gravity at early times, due to the increased curvature-dependent fermion mass. Investigating the scenario at the perturbation level, using the correct coupling parameter, the scalar spectral index and tensor-to-scalar ratio are obtained in agreement with Planck observations. Moreover the big bang nucleosynthesis constraints are satisfied too. The efficiency of inflation from fermions with curvature-dependent mass, at both the background and perturbation level, reveals the capabilities of the scenario and makes it a good candidate for the description of nature.

ACS Style

D. Benisty; E. I. Guendelman; E. N. Saridakis; H. Stoecker; J. Struckmeier; D. Vasak. Inflation from fermions with curvature-dependent mass. Physical Review D 2019, 100, 043523 .

AMA Style

D. Benisty, E. I. Guendelman, E. N. Saridakis, H. Stoecker, J. Struckmeier, D. Vasak. Inflation from fermions with curvature-dependent mass. Physical Review D. 2019; 100 (4):043523.

Chicago/Turabian Style

D. Benisty; E. I. Guendelman; E. N. Saridakis; H. Stoecker; J. Struckmeier; D. Vasak. 2019. "Inflation from fermions with curvature-dependent mass." Physical Review D 100, no. 4: 043523.

Journal article
Published: 20 June 2019 in Universe
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The long-awaited detection of a gravitational wave from the merger of a binary neutron star in August 2017 (GW170817) marks the beginning of the new field of multi-messenger gravitational wave astronomy. By exploiting the extracted tidal deformations of the two neutron stars from the late inspiral phase of GW170817, it is now possible to constrain several global properties of the equation of state of neutron star matter. However, the most interesting part of the high density and temperature regime of the equation of state is solely imprinted in the post-merger gravitational wave emission from the remnant hypermassive/supramassive neutron star. This regime was not observed in GW170817, but will possibly be detected in forthcoming events within the current observing run of the LIGO/VIRGO collaboration. Numerous numerical-relativity simulations of merging neutron star binaries have been performed during the last decades, and the emitted gravitational wave profiles and the interior structure of the generated remnants have been analysed in detail. The consequences of a potential appearance of a hadron-quark phase transition in the interior region of the produced hypermassive neutron star and the evolution of its underlying matter in the phase diagram of quantum cromo dynamics will be in the focus of this article. It will be shown that the different density/temperature regions of the equation of state can be severely constrained by a measurement of the spectral properties of the emitted post-merger gravitational wave signal from a future binary compact star merger event.

ACS Style

Matthias Hanauske; Luke Bovard; Elias Most; Jens Papenfort; Jan Steinheimer; Anton Motornenko; Volodymyr Vovchenko; Veronica Dexheimer; Stefan Schramm; Horst Stöcker. Detecting the Hadron-Quark Phase Transition with Gravitational Waves. Universe 2019, 5, 156 .

AMA Style

Matthias Hanauske, Luke Bovard, Elias Most, Jens Papenfort, Jan Steinheimer, Anton Motornenko, Volodymyr Vovchenko, Veronica Dexheimer, Stefan Schramm, Horst Stöcker. Detecting the Hadron-Quark Phase Transition with Gravitational Waves. Universe. 2019; 5 (6):156.

Chicago/Turabian Style

Matthias Hanauske; Luke Bovard; Elias Most; Jens Papenfort; Jan Steinheimer; Anton Motornenko; Volodymyr Vovchenko; Veronica Dexheimer; Stefan Schramm; Horst Stöcker. 2019. "Detecting the Hadron-Quark Phase Transition with Gravitational Waves." Universe 5, no. 6: 156.

Journal article
Published: 02 January 2019 in Particles
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Gravitational waves, electromagnetic radiation, and the emission of high energy particles probe the phase structure of the equation of state of dense matter produced at the crossroad of the closely related relativistic collisions of heavy ions and of binary neutron stars mergers. 3 + 1 dimensional special- and general relativistic hydrodynamic simulation studies reveal a unique window of opportunity to observe phase transitions in compressed baryon matter by laboratory based experiments and by astrophysical multimessenger observations. The astrophysical consequences of a hadron-quark phase transition in the interior of a compact star will be focused within this article. Especially with a future detection of the post-merger gravitational wave emission emanated from a binary neutron star merger event, it would be possible to explore the phase structure of quantum chromodynamics. The astrophysical observables of a hadron-quark phase transition in a single compact star system and binary hybrid star merger scenario will be summarized within this article. The FAIR facility at GSI Helmholtzzentrum allows one to study the universe in the laboratory, and several astrophysical signatures of the quark-gluon plasma have been found in relativistic collisions of heavy ions and will be explored in future experiments.

ACS Style

Matthias Hanauske; Jan Steinheimer; Anton Motornenko; Volodymyr Vovchenko; Luke Bovard; Elias R. Most; L. Jens Papenfort; Stefan Schramm; Horst Stöcker. Neutron Star Mergers: Probing the EoS of Hot, Dense Matter by Gravitational Waves. Particles 2019, 2, 44 -56.

AMA Style

Matthias Hanauske, Jan Steinheimer, Anton Motornenko, Volodymyr Vovchenko, Luke Bovard, Elias R. Most, L. Jens Papenfort, Stefan Schramm, Horst Stöcker. Neutron Star Mergers: Probing the EoS of Hot, Dense Matter by Gravitational Waves. Particles. 2019; 2 (1):44-56.

Chicago/Turabian Style

Matthias Hanauske; Jan Steinheimer; Anton Motornenko; Volodymyr Vovchenko; Luke Bovard; Elias R. Most; L. Jens Papenfort; Stefan Schramm; Horst Stöcker. 2019. "Neutron Star Mergers: Probing the EoS of Hot, Dense Matter by Gravitational Waves." Particles 2, no. 1: 44-56.

Article
Published: 26 November 2018 in Physical Review D
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The covariant canonical gauge theory of gravity is generalized by including at the Lagrangian level all possible quadratic curvature invariants. In this approach, the covariant Hamiltonian principle and the canonical transformation framework are applied to derive a Palatini type gauge theory of gravity. The metric gμν, the affine connection γλμν and their respective conjugate momenta, kμνσ and qηαξβ tensors, are the independent field components describing the gravity. The metric is the basic dynamical field, and the connection is the gauge field. The torsion-free and metricity-compatible version of the spacetime Hamiltonian is built from all possible invariants of the qηαξβ tensor components up to second order. These correspond in the Lagrangian picture to Riemann tensor invariants of the same order. We show that the quadratic tensor invariant is necessary for constructing the canonical momentum field from the gauge field derivatives, and hence for transforming between Hamiltonian and Lagrangian pictures. Moreover, the theory is extended by dropping metric compatibility and enforcing conformal invariance. This approach could be used for the quantization of the quadratic curvature theories, as for example in the case of conformal gravity.

ACS Style

David Benisty; Eduardo I. Guendelman; David Vasak; Jurgen Struckmeier; Horst Stoecker. Quadratic curvature theories formulated as covariant canonical gauge theories of gravity. Physical Review D 2018, 98, 106021 .

AMA Style

David Benisty, Eduardo I. Guendelman, David Vasak, Jurgen Struckmeier, Horst Stoecker. Quadratic curvature theories formulated as covariant canonical gauge theories of gravity. Physical Review D. 2018; 98 (10):106021.

Chicago/Turabian Style

David Benisty; Eduardo I. Guendelman; David Vasak; Jurgen Struckmeier; Horst Stoecker. 2018. "Quadratic curvature theories formulated as covariant canonical gauge theories of gravity." Physical Review D 98, no. 10: 106021.

Conference paper
Published: 02 February 2018 in EPJ Web of Conferences
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In this proceeding we review our recent work using supervised learning with a deep convolutional neural network (CNN) to identify the QCD equation of state (EoS) employed in hydrodynamic modeling of heavy-ion collisions given only final-state particle spectra ρ(pT, Ф). We showed that there is a traceable encoder of the dynamical information from phase structure (EoS) that survives the evolution and exists in the final snapshot, which enables the trained CNN to act as an effective “EoS-meter” in detecting the nature of the QCD transition.

ACS Style

Kai Zhou; Long-Gang Pang; Nan Su; Hannah Petersen; Horst Stoecker; Xin-Nian Wang. Identifying QCD Transition Using Deep Learning. EPJ Web of Conferences 2018, 171, 16005 .

AMA Style

Kai Zhou, Long-Gang Pang, Nan Su, Hannah Petersen, Horst Stoecker, Xin-Nian Wang. Identifying QCD Transition Using Deep Learning. EPJ Web of Conferences. 2018; 171 ():16005.

Chicago/Turabian Style

Kai Zhou; Long-Gang Pang; Nan Su; Hannah Petersen; Horst Stoecker; Xin-Nian Wang. 2018. "Identifying QCD Transition Using Deep Learning." EPJ Web of Conferences 171, no. : 16005.

Conference paper
Published: 01 August 2017 in Nuclear and Particle Physics Proceedings
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ACS Style

Wei Chen; Long-Gang Pang; Horst Stoecker; Luo Tan; Enke Wang; Xin-Nian Wang. Jet-induced medium excitations in γ -hadron correlation. Nuclear and Particle Physics Proceedings 2017, 289-290, 317 -320.

AMA Style

Wei Chen, Long-Gang Pang, Horst Stoecker, Luo Tan, Enke Wang, Xin-Nian Wang. Jet-induced medium excitations in γ -hadron correlation. Nuclear and Particle Physics Proceedings. 2017; 289-290 ():317-320.

Chicago/Turabian Style

Wei Chen; Long-Gang Pang; Horst Stoecker; Luo Tan; Enke Wang; Xin-Nian Wang. 2017. "Jet-induced medium excitations in γ -hadron correlation." Nuclear and Particle Physics Proceedings 289-290, no. : 317-320.

Conference paper
Published: 14 December 2016 in Proceedings of 54th International Winter Meeting on Nuclear Physics — PoS(BORMIO2016)
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ACS Style

Horst Stoecker; Volodymyr Vovchenko; Long-Gang Pang; Harri Niemi; Iurii A Karpenko; Mark Gorenstein; Leonid Satarov; Igor Mishustin; Burkhard Kämpfer. Hydrodynamic modeling of a pure-glue initial scenario in high-energy hadron and heavy-ion collisions. Proceedings of 54th International Winter Meeting on Nuclear Physics — PoS(BORMIO2016) 2016, 272, 039 .

AMA Style

Horst Stoecker, Volodymyr Vovchenko, Long-Gang Pang, Harri Niemi, Iurii A Karpenko, Mark Gorenstein, Leonid Satarov, Igor Mishustin, Burkhard Kämpfer. Hydrodynamic modeling of a pure-glue initial scenario in high-energy hadron and heavy-ion collisions. Proceedings of 54th International Winter Meeting on Nuclear Physics — PoS(BORMIO2016). 2016; 272 ():039.

Chicago/Turabian Style

Horst Stoecker; Volodymyr Vovchenko; Long-Gang Pang; Harri Niemi; Iurii A Karpenko; Mark Gorenstein; Leonid Satarov; Igor Mishustin; Burkhard Kämpfer. 2016. "Hydrodynamic modeling of a pure-glue initial scenario in high-energy hadron and heavy-ion collisions." Proceedings of 54th International Winter Meeting on Nuclear Physics — PoS(BORMIO2016) 272, no. : 039.

Journal article
Published: 01 December 2016 in Nuclear Physics A
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ACS Style

Wei Chen; Long-Gang Pang; Horst Stoecker; Tan Luo; Enke Wang; Xin-Nian Wang. Jet-induced medium excitation in heavy-ion collisions. Nuclear Physics A 2016, 956, 605 -608.

AMA Style

Wei Chen, Long-Gang Pang, Horst Stoecker, Tan Luo, Enke Wang, Xin-Nian Wang. Jet-induced medium excitation in heavy-ion collisions. Nuclear Physics A. 2016; 956 ():605-608.

Chicago/Turabian Style

Wei Chen; Long-Gang Pang; Horst Stoecker; Tan Luo; Enke Wang; Xin-Nian Wang. 2016. "Jet-induced medium excitation in heavy-ion collisions." Nuclear Physics A 956, no. : 605-608.

Preprint
Published: 01 December 2008
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A systematic study of HBT radii of pions, produced in heavy ion collisions in the intermediate energy regime (SPS), from an integrated (3+1)d Boltzmann+hydrodynamics approach is presented. The calculations in this hybrid approach, incorporating an hydrodynamic stage into the Ultra-relativistic Quantum Molecular Dynamics transport model, allow for a comparison of different equations of state retaining the same initial conditions and final freeze-out. The results are also compared to the pure cascade transport model calculations in the context of the available data. Furthermore, the effect of different treatments of the hydrodynamic freeze-out procedure on the HBT radii are investigated. It is found that the HBT radii are essentially insensitive to the details of the freeze-out prescription as long as the final hadronic interactions in the cascade are taken into account. The HBT radii $R_L$ and $R_O$ and the $R_O/R_S$ ratio are sensitive to the EoS that is employed during the hydrodynamic evolution. We conclude that the increased lifetime in case of a phase transition to a QGP (via a Bag Model equation of state) is not supported by the available data.

ACS Style

Qingfeng Li; Jan Steinheimer; Hannah Petersen; Marcus Bleicher; Horst Stoecker. Effects of a phase transition on HBT correlations in an integrated Boltzmann+Hydrodynamics approach. 2008, 1 .

AMA Style

Qingfeng Li, Jan Steinheimer, Hannah Petersen, Marcus Bleicher, Horst Stoecker. Effects of a phase transition on HBT correlations in an integrated Boltzmann+Hydrodynamics approach. . 2008; ():1.

Chicago/Turabian Style

Qingfeng Li; Jan Steinheimer; Hannah Petersen; Marcus Bleicher; Horst Stoecker. 2008. "Effects of a phase transition on HBT correlations in an integrated Boltzmann+Hydrodynamics approach." , no. : 1.