Directed, elliptic and higher order flow harmonics of protons, deuterons and tritons in Au+Au collisions at $\sqrt{s_{NN}} = 2.4$ GeV

The HADES collaboration Adamczewski-Musch, J. ; Arnold, O. ; Behnke, C. ; et al.
Phys.Rev.Lett. 125 (2020) 262301, 2020.
Inspire Record 1797626 DOI 10.17182/hepdata.102468

Flow coefficients $v_{n}$ of the orders $n = 1 - 6$ are measured with the High-Acceptance DiElectron Spectrometer (HADES) at GSI for protons, deuterons and tritons as a function of centrality, transverse momentum and rapidity in Au+Au collisions at $\sqrt{s_{NN}} = 2.4$ GeV. Combining the information from the flow coefficients of all orders allows to construct for the first time, at collision energies of a few GeV, a multi-differential picture of the angular emission pattern of these particles. It reflects the complicated interplay between the effect of the central fireball pressure on the emission of particles and their subsequent interaction with spectator matter. The high precision information on higher order flow coefficients is a major step forward in constraining the equation-of-state of dense baryonic matter.

18 data tables

The $p_{t}$ dependence of $v_{1}$ for protons, deuterons and tritons in the rapidity interval $-0.25 < y_{cm} < -0.15$ in semi-central ($20 - 30$ %) $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{{s}_{NN}}=2.4$ GeV.

The $p_{t}$ dependence of $v_{3}$ for protons, deuterons and tritons in the rapidity interval $-0.25 < y_{cm} < -0.15$ in semi-central ($20 - 30$ %) $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{{s}_{NN}}=2.4$ GeV.

The $p_{t}$ dependence of $v_{5}$ for protons, deuterons and tritons in the rapidity interval $-0.25 < y_{cm} < -0.15$ in semi-central ($20 - 30$ %) $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{{s}_{NN}}=2.4$ GeV.

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Charged pion production in $\mathbf{Au+Au}$ collisions at $\mathbf{\sqrt{s_{NN}}}$ = 2.4$\mathbf{GeV}$

The HADES collaboration Adamczewski-Musch, J. ; Arnold, O. ; Behnke, C. ; et al.
Eur.Phys.J.A 56 (2020) 259, 2020.
Inspire Record 1796710 DOI 10.17182/hepdata.97368

We present high-statistic data on charged pion emission from Au+Au collisions at $\sqrt{s_{\rm{NN}}}$ = 2.4 GeV (corresponding to $E_{beam}$ = 1.23 A GeV) in four centrality classes in the range 0 - 40$\%$ of the most central collisions. The data are analyzed as a function of transverse momentum, transverse mass, rapidity, and polar angle. Pion multiplicity per participating nucleon decreases moderately with increasing centrality. The polar angular distributions are found to be non-isotropic even for the most central event class. Our results on pion multiplicity fit well into the general trend of the world data, but undershoot by $2.5 \sigma$ data from the FOPI experiment measured at slightly lower beam energy. We compare our data to state-of-the-art transport model calculations (PHSD, IQMD, PHQMD, GiBUU and SMASH) and find substantial differences between the measurement and the results of these calculations.

11 data tables

Mid-rapidity and forward rapidity transverse momentum distributions ($p_{t}$) for charged pion for the 10$\%$most central events.

Reduced transverse mass distribution for negatively charged pions in rapidity bins of $\Delta y_{cm}$ = 0.1width between -0.65 and 0.75 for 0-10$\%$ most central events. The most backward rapidity is shown unscaledwhile for following rapidity slices are scaled up by succesive factors of 10.

Reduced transverse mass distribution for positively charged pions in rapidity bins of $\Delta y_{cm}$ = 0.1width between -0.65 and 0.75 for 0-10$\%$ most central events. The most backward rapidity is shown unscaledwhile for following rapidity slices are scaled up by succesive factors of 10.

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Proton-Proton Interactions and Onset of Deconfinement

The NA61/SHINE collaboration Aduszkiewicz, A. ; Andronov, E.V. ; Anticic, T. ; et al.
Phys.Rev.C 102 (2020) 011901, 2020.
Inspire Record 1772241 DOI 10.17182/hepdata.95182

The NA61/SHINE experiment at the CERN SPS is performing a uniqe study of the phase diagram of strongly interacting matter by varying collision energy and nuclear mass number of colliding nuclei. In central Pb+Pb collisions the NA49 experiment found structures in the energy dependence of several observables in the CERN SPS energy range that had been predicted for the transition to a deconfined phase. New measurements of NA61/SHINE find intriguing similarities in p+p interactions for which no deconfinement transition is expected at SPS energies. Possible implications will be discussed.

12 data tables

K+/PI+ at y=0.

K+/PI+ at y=0.

<K+>/<PI+>.

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Version 2
Probing dense baryon-rich matter with virtual photons

The HADES collaboration Adamczewski-Musch, J. ; Arnold, O. ; Behnke, C. ; et al.
Nature Phys. 15 (2019) 1040-1045, 2019.
Inspire Record 1758156 DOI 10.17182/hepdata.90846

About 10 μs after the Big Bang, the universe was filled—in addition to photons and leptons—with strong-interaction matter consisting of quarks and gluons, which transitioned to hadrons at temperatures close to kT = 150 MeV and densities several times higher than those found in nuclei. This quantum chromodynamics (QCD) matter can be created in the laboratory as a transient state by colliding heavy ions at relativistic energies. The different phases in which QCD matter may exist depend for example on temperature, pressure or baryochemical potential, and can be probed by studying the emission of electromagnetic radiation. Electron–positron pairs emerge from the decay of virtual photons, which immediately decouple from the strong interaction, and thus provide information about the properties of QCD matter at various stages. Here, we report the observation of virtual photon emission from baryon-rich QCD matter. The spectral distribution of the electron–positron pairs is nearly exponential, providing evidence for a source of temperature in excess of 70 MeV with constituents whose properties have been modified, thus reflecting peculiarities of strong-interaction QCD matter. Its bulk properties are similar to the dense matter formed in the final state of a neutron star merger, as apparent from recent multimessenger observation.

10 data tables

Reconstructed $e^{+} e^{-}$ mass distribution from Au+Au collisions.

Reconstructed $e^{+} e^{-}$ mass distribution from Au+Au collisions.

Reconstructed $e^{+} e^{-}$ mass distribution from Au+Au collisions.

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Version 2
Sub-threshold production of K$^{0}_{s}$ mesons and ${\Lambda}$ hyperons in Au(1.23A GeV)$+$Au

The HADES collaboration Adamczewski-Musch, J. ; Arnold, O. ; Behnke, C. ; et al.
Phys.Lett.B 793 (2019) 457-463, 2019.
Inspire Record 1709767 DOI 10.17182/hepdata.90954

We present first data on sub-threshold production of K0 s mesons and {\Lambda} hyperons in Au+Au collisions at $\sqrt{s_{NN}}$ = 2.4 GeV. We observe an universal <Apart> scaling of hadrons containing strangeness, independent of their corresponding production thresholds. Comparing the yields, their <Apart> scaling, and the shapes of the rapidity and the pt spectra to state-of-the-art transport model (UrQMD, HSD, IQMD) predictions, we find that none of the latter can simultaneously describe all observables with reasonable \c{hi}2 values.

36 data tables

Example of $K^{0}_{S}$ signal for 0-40% most central events, over mixed-event background for the bin $-0.05 < y_{cm} < 0.05$ and reduced transverse masses between $80-120 MeV/c^{2}$.

Example of $K^{0}_{S}$ signal for 0-40% most central events, over mixed-event background for the bin $-0.05 < y_{cm} < 0.05$ and reduced transverse masses between $80-120 MeV/c^{2}$.

Example of $\Lambda$ signal for 0-40% most central events, over mixed-event background for the bin $-0.05 < y_{cm} < 0.05$ and reduced transverse masses between $100-150 MeV/c^{2}$.

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Version 3
Deep sub-threshold {\phi} production and implications for the K+/K- freeze-out in Au+Au collisions

The HADES collaboration Adamczewski-Musch, J. ; Arnold, O. ; Behnke, C. ; et al.
Phys.Lett.B 778 (2018) 403-407, 2018.
Inspire Record 1519164 DOI 10.17182/hepdata.92099

We present data on charged kaons (K+-) and {\phi} mesons in Au(1.23A GeV)+Au collisions. It is the first simultaneous measurement of K and {\phi} mesons in central heavy-ion collisions below a kinetic beam energy of 10A GeV. The {\phi}/K- multiplicity ratio is found to be surprisingly high with a value of 0.52 +- 0.16 and shows no dependence on the centrality of the collision. Consequently, the different slopes of the K+ and K- transverse-mass spectra can be explained solely by feed- down, which substantially softens the spectra of K- mesons. Hence, in contrast to the commonly adapted argumentation in literature, the different slopes do not necessarily imply diverging freeze- out temperatures of K+ and K- mesons caused by different couplings to baryons.

37 data tables

Acceptance and efficiency corrected transverse-mass spectra around mid-rapidity.

Acceptance and efficiency corrected transverse-mass spectra around mid-rapidity.

Acceptance and efficiency corrected transverse-mass spectra around mid-rapidity.

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Measurement of the $e^+e^- \to K^+K^-\pi^+\pi^-$ cross section with the CMD-3 detector at the VEPP-2000 collider

Shemyakin, D.N. ; Fedotovich, G.V. ; Akhmetshin, R.R. ; et al.
Phys.Lett.B 756 (2016) 153-160, 2016.
Inspire Record 1395968 DOI 10.17182/hepdata.76553

The process $e^+e^- \to K^+K^-\pi^+\pi^-$ has been studied in the center-of-mass energy range from 1500 to 2000\,MeV using a data sample of 23 pb$^{-1}$ collected with the CMD-3 detector at the VEPP-2000 $e^+e^-$ collider. Using about 24000 selected events, the $e^+e^- \to K^+K^-\pi^+\pi^-$ cross section has been measured with a systematic uncertainty decreasing from 11.7\% at 1500-1600\,MeV to 6.1\% above 1800\,MeV. A preliminary study of $K^+K^-\pi^+\pi^-$ production dynamics has been performed.

1 data table

Center-of-mass energy, integrated luminosity, number of four-track events, number of three-track events, detection efficiency, radiative correction and Born cross section of the process $e^{+}e^{-} \to K^{+} K^{-} \pi^{+} \pi^{-}$. Errors are statistical only.


$K^+$ nucleon elastic scattering at 180° between 1.0 and 1.5 GeV/c incident momentum

Adams, U. ; Carter, R.S. ; Cook, V. ; et al.
Nucl.Phys.B 87 (1975) 41-51, 1975.
Inspire Record 1392682 DOI 10.17182/hepdata.32061

We have measured the cross section at 180° for K + p and K + n elastic scattering in the momentum range 1.0 to 1.5 GeV/ c . The K + n cross section was measured on deuterium and the K + p on hydrogen and deuterium. We were thus able to measure directly the difference between free nucleon (proton) scattering and bound nucleon (proton) scattering at large angles. This difference was found to be small and within our experimental accuracy the K + p(n) cross section should be equal to the K + p (free) cross section at 180°. We found no evidence for an s -channel resonance Z ∗ in either the K + p or K + n system. A comparison of our data and those of other groups with theoretical predictions is given.

2 data tables

DEUTERIUM TARGET. U IS ABOUT 0.1 GEV**2.

HYDROGEN AND DEUTERIUM TARGET DATA ARE IN GOOD AGREEMENT. THESE CROSS SECTIONS ARE A WEIGHTED AVERAGE.


Pion production with polarized photons and test of vector dominance model

Geweniger, Chr. ; Heide, P. ; Kötz, U. ; et al.
Phys.Lett.B 28 (1968) 155-156, 1968.
Inspire Record 1392676 DOI 10.17182/hepdata.29098

Cross section asymmetries for the sum of single π + and π - production with polarized photons of 3.4 GeV have been measured. The results disagree with calculations based on the vector dominance model using experimental data of vector meson production in π beams.

1 data table

No description provided.


Single photoproduction of neutral π-mesons on hydrogen at small angles between 1.3 and 3 GeV

Braunschweig, M. ; Husmann, D. ; Lübelsmeyer, K. ; et al.
Phys.Lett. 22 (1966) 705-708, 1966.
Inspire Record 1389452 DOI 10.17182/hepdata.753

The differential cross section of the reaction γ + p → p + πo has been measured at the Deutsches Elektronen- Synchrotron, Hamburg, at mean phonon energies of 1.36, 2.0 and 3.0 GeV and pion center of mass angles between 0o and 70o. The results are compared with some theoretical calculations based on elementary and reggeized 1- meson exchange.

4 data tables

Axis error includes +- 12/12 contribution.

Axis error includes +- 12/12 contribution.

Axis error includes +- 12/12 contribution.

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