Dominique Dittert for the HADES Collaboration Outline Introduction

Dominique Dittert for the HADES Collaboration Outline • Introduction • Differential Spectra • Azimuthal Anisotropy • Recent Ag+Ag Beamtime • Summary 14. 05. 2019 | Dominique Dittert | New Trends in High Energy Physics – Odessa, Ukraine | 1

INTRODUCTION 14. 05. 2019 | Dominique Dittert | New Trends in High Energy Physics – Odessa, Ukraine | 2

The HADES Physics Case NS mergers HADES [Fig. credit: T. Galatyuk, M. Hanauske, F. Seck] 14. 05. 2019 | Dominique Dittert | New Trends in High Energy Physics – Odessa, Ukraine | 3

Electromagnetic radiation from the fireball Space-time evolution g g* l+ l. In medium r and w SF & QGP rates vs. time In-medium spectral fct. Collectivity Source of Radiation 14. 05. 2019 | Dominique Dittert | New Trends in High Energy Physics – Odessa, Ukraine | 4

High-Acceptance Di-Electron Spectrometer Photo: Jan Michael Hosan/HA Hessen Agentur Gmb. H • Fast detector → interaction rate: 8 k. Hz in Au+Au, 200 k. Hz at SIS 100 • Large acceptance → full azimuthal coverage, polar angles from 18 o to 85 o • Mass resolution → of the order of few % • Good particle identification • Efficient track reconstruction 14. 05. 2019 | Dominique Dittert | New Trends in High Energy Physics – Odessa, Ukraine | 5 Particle Identification Particle tracks and momenta Event plane reconstruction

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Dilepton Invariant Mass Spectrum 14. 05. 2019 | Dominique Dittert | New Trends in High Energy Physics – Odessa, Ukraine | 7

Centrality dependent Invariant Mass Spectra (Mc. Lerran - Toimela formula, Phys. Rev. D 31 (1985) 545) 14. 05. 2019 | Dominique Dittert | New Trends in High Energy Physics – Odessa, Ukraine | 8

pt-dependent preliminary → Hotter source of radiation in more central collisions → Hotter source of radiation at higher pt 14. 05. 2019 | Dominique Dittert | New Trends in High Energy Physics – Odessa, Ukraine | 9 Interesting behaviour → Models are needed

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Rapidity dependent dilepton distributions 0. 15 < Mee [Ge. V/c 2] < 0. 3 < Mee [Ge. V/c 2] < 0. 45 y. CM = 0. 74 0. 45 < Mee [Ge. V/c 2] < 0. 6 y. CM 14. 05. 2019 | Dominique Dittert 0. 6 < Mee [Ge. V/c 2] < 1. 0 y. CM | New Trends in High Energy Physics – Odessa, Ukraine | 11

Inverse Slope Analysis y-dependent 14. 05. 2019 | Dominique Dittert | New Trends in High Energy Physics – Odessa, Ukraine | 12

AZIMUTHAL ANISOTROPY 14. 05. 2019 | Dominique Dittert | New Trends in High Energy Physics – Odessa, Ukraine | 13

Invariant Mass dependent Azimuthal Anisotopy HADES preliminary 14. 05. 2019 | Dominique Dittert | New Trends in High Energy Physics – Odessa, Ukraine | 14

HADES preliminary 14. 05. 2019 | Dominique Dittert HADES preliminary | New Trends in High Energy Physics – Odessa, Ukraine | 15

Azimuthal Anisotropy Centrality-dependent HADES preliminary 14. 05. 2019 | Dominique Dittert HADES preliminary | New Trends in High Energy Physics – Odessa, Ukraine | 16

Azimuthal Anisotropy y-dependent HADES preliminary 14. 05. 2019 | Dominique Dittert HADES preliminary | New Trends in High Energy Physics – Odessa, Ukraine | 17

HADES preliminary 14. 05. 2019 | Dominique Dittert | New Trends in High Energy Physics – Odessa, Ukraine | 18

Ag+Ag @ 1. 58 A Ge. V 14. 05. 2019 | Dominique Dittert | New Trends in High Energy Physics – Odessa, Ukraine | 19

FAIR Phase-0 Experiment Event display ~ 15 billion events were collected during March 2019 14. 05. 2019 | Dominique Dittert | New Trends in High Energy Physics – Odessa, Ukraine | 20

Refurbished RICH-Detector Old MWPC photon detector replaced by an array of PMTs One can detect dileptons on an event display 14. 05. 2019 | Dominique Dittert | New Trends in High Energy Physics – Odessa, Ukraine | 21

Lepton Identification System 0: • q < 45 deg • Timing with RPC Default track selection and double hit rejection Simple lepton PID System 1: • q > 45 deg • Timing with scintillator → Almost no new calibrations yet → Very rough cuts → Still, it is possible to extract clean lepton sample 14. 05. 2019 | Dominique Dittert | New Trends in High Energy Physics – Odessa, Ukraine | 22

Dilepton Invariant Mass HADES online Signal-to-background ratio much better than in Au+Au! 14. 05. 2019 | Dominique Dittert | New Trends in High Energy Physics – Odessa, Ukraine | 23 • Asymmetry for reconstruction of like- and unlike-sign pairs • Very similar like in Au+Au, but far higher precision is possible

Summary preliminary y. CM Outlook • Analysis of more peripheral events • Analysis of the recent Ag+Ag beamtime 14. 05. 2019 | Dominique Dittert | New Trends in High Energy Physics – Odessa, Ukraine | 24

THANK YOU FOR YOUR ATTENTION 14. 05. 2019 | Dominique Dittert | New Trends in High Energy Physics – Odessa, Ukraine | 25

BACKUP 14. 05. 2019 | Dominique Dittert | New Trends in High Energy Physics – Odessa, Ukraine | 26

Lepton Identification • Particle Reconstruction • Track Reconstruction: Hit positions in MDC planes • Momentum Reconstruction: Deflection in the magnetic field • META-Matching: Combining MDC tracks and time-of-flight information • RICH Ring Reconstruction: Ring Finder Algorithm or Backtracking • Event Selection • Sector Quality • Centrality Selection • Event Plane Reconstruction Single Lepton Identification • Multivariate Analysis using a Multi-Layer Perceptron • 14. 05. 2019 | Dominique Dittert | New Trends in High Energy Physics – Odessa, Ukraine | 27

Dilepton Analysis Combinatorial Background • Same-Event Like-Sign Geometric-Mean • Mixed-Event Background • Correction for sign dependent reconstruction asymmetries Efficiency and Acceptance Corrections NN Reference Ring Finder Backtracking 14. 05. 2019 | Dominique Dittert | New Trends in High Energy Physics – Odessa, Ukraine | 28

0 < p. T, ee [Ge. V/c] < 0. 2 < p. T, ee [Ge. V/c] < 0. 4 < p. T, ee [Ge. V/c] < 1. 0 → Less steep at higher pt S. Damjanowic → Similar observation as for IMR dimuons at SPS NA 60 ( Trento 2010 ) 14. 05. 2019 | Dominique Dittert | New Trends in High Energy Physics – Odessa, Ukraine | 29

Comparison to model calculations 0 < Mee [Ge. V/c 2] < 0. 15 < Mee [Ge. V/c 2] < 0. 3 < Mee [Ge. V/c 2] < 0. 45 < Mee [Ge. V/c 2] < 0. 6 → Spectra consistent with the models 14. 05. 2019 | Dominique Dittert | New Trends in High Energy Physics – Odessa, Ukraine | 30 0. 6 < Mee [Ge. V/c 2] < 1. 0