The Physics of Dense Nuclear Matter

Introduction

StatusNear future

Perspectives at FAIR

Joachim Stroth

Univ. Frankfurt / GSI

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Dense nuclear matter in the laboratory

What are the properties of dense nuclear matter?

Dense matter Freeze-outFirst chance collisions

Its macroscopic properties depend on the microscopic structure! → Hadron physics (in-medium)

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The physics case

J. Wambach et al.

0,0

,

T

T

qq

qq Does the quark model provide the right description of hadrons?

What is the relevant excitation spectrum as the matter density increases?

What is the role of chiral symmetry breaking in the generation of hadron masses?

Where are the limits of hadronic existence?

Matter properties (EOS) of compact stars!

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Pionic bound states are clearly observed. The measured binding energies evidence

a reduced expectation value of the Chiral Condensate at nuclear ground state density.

Pionic atomsPionic atoms

Fragment separator at GSI used as high-resolution forward spectrometer

• Collaboration• Nava, GSI, Munich, Jülich, Tokyo, Niigata, RIKEN

Mesonic Atoms Experiments combine techniques from

hadron and heavy ion physics.(inelastic NN reaction and pick-up).

Pions with favorable momentum are trapped in the Coulomb-field of the heavy Nucleus.

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Ni+Ni @ 1.93 AGeV central collisions

M. Menzel et al., KaoS Collab., Phys. Lett. B 495 (2000) 26K. Wisniewski et al., FOPI Collab., Eur. Phys. J A 9 (2000) 515Transport calculations: G.Q. Li & G.E. Brown

In-medium mass of strange mesons In-medium mass of strange mesons

In-medium potential of strange mesons should lead to shift a of the effective kaon mass!

Indication observed in heavy ion reaction at the SIS18, GSI by KAOS and FOPI.

K-

K+

KAOS results selected among the 10 most important physics results in 1998 (APS)

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Kaonic bound statesKaonic bound states

Exotic bound states with strangeness Attractive K- N potential results in additional binding Production mechanisms presently uncertain, might be populated in HI

collisions but probably also in induced reactions.

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preliminary

12C+ 12C 2 AGeV

e+

e-

208Pb

-

n

HADESHigh Acceptance Dielectron Spectrometer

Low-mass vector mesons Detected by electron pair reconstruction

(penetrating probes).

Spectrometer with high invariant mass resolution and high rate capability.

operational since 2001 at GSI.

Beams of:– Pions– Protons– Nuclei

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Primary Beams

• 1012/spill; 1.5-2 GeV/u; 238U28+

• Factor 100-1000 over present in intensity• 2(4)x1013/spill 30 GeV protons• 1010/spill 238U73+ up to 35 GeV/u • up to 90 GeV protons

Secondary Beams

• Broad range of radioactive beams up to1.5 - 2 GeV/u; up to factor 10 000 in intensity over present

• Antiprotons 3 - 30 GeV

Key Technical Features• Cooled beams• Rapidly cycling superconducting magnets

Storage and Cooler Rings

• Radioactive beams

• e- – A (or Antiproton-A) collider

• stored and cooled 0.8 - 14.5GeV antiprotons

UNILACSIS

SIS 100/300

International FAIR Project: SIS300

CBM

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The energy scan at SPS (NA94)

Exiting observations at an energy of around 30 AGeV

→ Relative enhancement of strangeness

→ Not explained by transport calculationsand statistical model

SPS heavy ion program suspended due to priority for LHC

CERN SPS-C:

"The search for the critical point is of high importance for the understanding of QCD. .... Respective proposals can be accepted for a time period after 2008". Integrated Luminosity ?

NA49, M. Gazdzicki et al.

Fluctuations due to approach of the critical point ??

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The Compressed Baryonic Matter program

CBM Detector

Heavy ion collisions Heavy ion collisions at interaction rates of up to 10at interaction rates of up to 1077 Hz Hz

Excitation functions from 2 to 35 GeV/uExcitation functions from 2 to 35 GeV/u

Experimental goal of the CBM collaboration:

Systematic investigation of dense baryonic matter using penetrating and rare probes!

Observables:Penetrating probes: , , , J/ Strangeness: K, , , , , Open charm: Do, D

Hadrons ( p, π), exotica

HADES

Needs large integrated luminosity:High beam intensity and duty cycle,available for several month per year

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Physics program of CBM

SIS18 SIS300

Fluctuations in the strangeness production

• Signal for the critical point

Low mass electron pairs

• Probe the in-medium structure of hadrons

Near threshold open-charm production

• Analogy to strangeness at 1-2- AGeV

Charmonium production

• Sensitive to the early state of the matter

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The physics community

FOPI upgrade → heavy ion program world-wide unique

European collaboration + Japan: 50 physicist

Bucharest, Budapest, Clermont-Ferrand, Darmstadt, Dresden, Florence, Heidelberg, Moscow, Seoul, Strasbourg, Warszawa, Zagreb

HADES → heavy ions world-wide unique (elementary JLAB, KEK)

European collaboration: 120 physicist

Bratislava, Catania, Dubna, Frankfurt, Giessen, Milano, Moscow, Garching, Nicosia, Orsay, Rez, Dresden, Santiago de Compostela, Valencia

CBM → RHIC low energy program uncertain, SPS suspended

International collaboration: >300 physicistFurther interest by people from former NA49 experiment – CERN proposal ?

Theory → Microscopic transport essential

Smaller groups at different universities

FP6 I3HP

FP6 I3HP

FP6 I3HP

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Motivation: II

„The challenge for the next century physics is: explain confinement and broken (chiral) symmetry“

T.D. LeeT.D. Lee

„But perhaps the most interesting and surprising thing about QCD at high density is that, by thinking about it, one discovers

a fruitful new perspective on the traditional problem of confinement and chiral-symmetry breaking”.

F. WilczekF. Wilczek