The Physics of CBM Volker Friese GSI Darmstadt CBM-China Workshop, Beijing, 2 November 2009

The Mission CBM-China Workshop, Beijing, 2 November 2009Volker Friese2  study of QCD matter at the highest net baryon densities achievable in the laboratory  search for the 1st order phase transition from confined to deconfined matter  search for restoration of chiral symmetry  search for the critical endpoint of the QCD phase diagram

The Messengers CBM-China Workshop, Beijing, 2 November 2009Volker Friese3 First collisions(Equilibrated ?) fireball Hadronisation Chemical freeze-out Kinematic freeze-out Free streaming particles

The Tools CBM-China Workshop, Beijing, 2 November 2009Volker Friese4 RICH TRD TOF ECAL PSD absorber + detectors Electron + Hadron setupMuon setup STS+MVD  Hyperons: STS  Muons: STS + MUCH+ TOF  Hadrons: STS + TRD + TOF  Hyperons: STS  Open charm: STS + MVD  Electrons: STS + RICH + TRD + TOF + ECAL  Photons: ECAL

The Strategy CBM-China Workshop, Beijing, 2 November 2009Volker Friese5 Energy density transverse momentum volume charm, strangeness antibaryons elliptic flow e-by-e fluctuations high pt hadrons heavy quarkonia mass and width of ρ,ω,φ thermal photons and dileptons  Phase transitions will show up in non-monotonic behaviour of observables as function of collision energy  Measure excitation functions of yields, spectral shapes, flow, fluctuations,.... Yagi, Hatsuda, Miake: Quark-Gluon Plasma (2006)

Observables: Open Charm CBM-China Workshop, Beijing, 2 November 2009Volker Friese6  charm is produced in first hard collisions: carries informations on all stages of the collision  different predictions of open charm yield in hadronic (HSD) or partonic (pQCD + statistical hadronisation) pictures  no measurements in heavy-ion collisions below RHIC energy  very rare probe at FAIR energies! W. Cassing et al., Nucl. Phys. A 691 (2001) 753 A. Andronic et al., arXiv: HSD SHM

Open Charm in Dense Medium CBM-China Workshop, Beijing, 2 November 2009Volker Friese7  Mass shifts expected for D mesons in dense environment  Reduced effective mass for both D and anti-D  Large effect on yield near production threshold  Opening of strong decay channels for charmonia (?) Mishra et al, nucl-th/

Open Charm Detection in CBM CBM-China Workshop, Beijing, 2 November 2009Volker Friese8  Micro-Vertex Detector (2 stations of MAPS) with low material budget and high coordinate resolution  allows vertex resolution of 50 – 80 μm

Open Charm in CBM: D ± mesons CBM-China Workshop, Beijing, 2 November 2009Volker Friese9  excellent S/B ratio for D ± decay  good p t and rapidity coverage  good statistics (16 k D + in 25 d 10 6 interactions / second

Open Charm: Other Channels CBM-China Workshop, Beijing, 2 November 2009Volker Friese10 D 0 -> K - π + + c.c. Λ c + -> p K - π + D s + -> K - K + π + D 0 -> K - π - π + π +

Charmonium CBM-China Workshop, Beijing, 2 November 2009Volker Friese11 rescal ed to 158 GeV  (sequential) charmonium suppression predicted for QGP (Debye screening)  observations by NA50/NA60 and PHENIX, but interpretation debated  no measurements below top SPS energy  ratio hidden / open charm very sensitive to charm production mechanism J/ψ Ψ‘

Charmonium in CBM CBM-China Workshop, Beijing, 2 November 2009Volker Friese12 e+e - μ+μ-μ+μ-  Rarest probe for CBM: requires highest interaction rates (10 MHz)  Measurements via electrin pairs (RICH, TRD, TOF) or muon pairs (MUCH)  Similar performance in both channels: good S/B for J/ψ; ψ‘ will be difficult see talk by T. Galatyuk

Observables: Strangeness CBM-China Workshop, Beijing, 2 November 2009Volker Friese13  originally thought sensitive to QGP  but: reasonable description by statistical model  some features at lower SPS energies debated  lack of precision measurements, in particular for multi- strange baryons

Hyperon measurements CBM-China Workshop, Beijing, 2 November 2009Volker Friese14 ΛΞ-Ξ- Ω-Ω- Identified by decay topology in STS + inv. Mass New and fast rec. Software Clean signals: almost background free for Λ and Ξ No identification of secondaries required simulation and reconstruction: central 25A GeV

Erotic Exotics: Multi-strange di-baryons CBM-China Workshop, Beijing, 2 November 2009Volker Friese15 {Ξ 0, Λ} Thermal production yields for hyperon clusters Started to study {Ξ 0, Λ} → ΛΛ Assuming: m=m Λ + m Ξ cτ = 3 cm (1-5 cm) BR = 2 % (1-10 %) J. Schaffner-Bielich, R. Mattiello and H. Sorge, 1999 J. Steinheimer, priv. comm.

CBM Sensitivity for {Ξ 0, Λ} CBM-China Workshop, Beijing, 2 November 2009Volker Friese16 Thermal multiplicity (7  ) Sensitivity limit: 7  CBM will see {Ξ 0, Λ} with thermal yields Evene three OOM below the signal will be visible above BG ≈ 30 d data taking at 10 7 MHz

Observables: Fluctuations CBM-China Workshop, Beijing, 2 November 2009Volker Friese17 multiplicitynet chargemean p t  results on multiplicity, net charge, mean p t so far null or in line with hadronic transport  deviation from transport seen in K/π  finite volume / lifetime of fireball possibly suppresses fluctuations  role of hadronic rescattering?

K/π in CBM CBM-China Workshop, Beijing, 2 November 2009Volker Friese18  CBM-TOF allows good kaon ID in a large acceptanc region  small acceptance + PID bias introduced in fluctuation measure central 25A GeV

Observables: In-Medium Vector Mesons CBM-China Workshop, Beijing, 2 November 2009Volker Friese19  modification of mass / width expected in dense matter: restoration of chiral symmetry ?  observable for short-lived vector mesons in di-leptonic decay channels  measurements between 2 and 40 A GeV lacking! (maximum density!)

Low-Mass Vector Mesons in CBM CBM-China Workshop, Beijing, 2 November 2009Volker Friese20 LVM→μμ LVM→e + e - central 25A GeV  Difficult measurement, but feasible in both electron and muon channels  S/B well above competitors see talk by T. Galatyuk

Observables: Flow CBM-China Workshop, Beijing, 2 November 2009Volker Friese21  elliptic flow sensitive to EOS  model predicitions with and without phase transition differ strongly  AMPT model predicts quark number scaling also at FAIR energies (with phase transition) AMPT model, C. Ko et al.

CBM Physics at SIS-100 CBM-China Workshop, Beijing, 2 November 2009Volker Friese22  temporal offset of SIS-300 w.r.t. SIS-100 possible  physics programme of CBM at SIS-100:  A+A up to 10A GeV  strangeness excitation function (incl. flow)  p+p, p+A up to 29 GeV  open charm

Open Charm With Proton Beam CBM-China Workshop, Beijing, 2 November 2009Volker Friese23  cross sections close to threshold unknwon for open charm also in p+p and p+A  provides important restriction of models for A+A  measurement in CBM is possible with proton beam from SIS GeV

Acceptance for SIS-100 CBM-China Workshop, Beijing, 2 November 2009Volker Friese24  satisfactory acceptance down to 4A GeV without modification of setup  measurement is possible without intermediate tracker (TRD)