Measurement of light flavor hadrons and anti-nuclei with ALICE

2012-OCT-09 | Quark Confinement and the Hadron Spectrum Conference -- Munich

Alexander Kalweit, CERN

for the ALICE collaboration

2012-OCT-09 | alexander.philipp.kalweit@cern.ch

Overview

• The ALICE experiment and its excellent particle identification capabilities.

• Hadron chemistry in pp and Pb-Pb collisions at the LHC.

• Anti-matter production at the LHC.

• Hyper-matter production at the LHC: searches for exotica.

• Outlook

• Even more details: next talk by Francesca..

2

ALICEpp @ 7 TeV

2012-OCT-09 | alexander.philipp.kalweit@cern.ch

The ALICE detector at the LHC

3

Particle identification

2012-OCT-09 | Quark Confinement and the Hadron Spectrum Conference -- Munich

2012-OCT-09 | alexander.philipp.kalweit@cern.ch

Particle identification (1)

5

• The ALICE experiment employs all known techniques for hadron identification:

• dE/dx in ITS, for very low-momenta tracks (pT ≈ 100 MeV/c), σ ≈ 10-15%

• dE/dx in TPC, at low and very high momenta (rel. rise), σ ≈ 5.2% (pp) -> 6.5% (Pb-Pb central)

• Time-Of-Flight, intermediate pT,σ ≈ 85 ps (Pb-Pb) -> 120 ps (pp)

• HMPID, Cerenkov radiation

2012-OCT-09 | alexander.philipp.kalweit@cern.ch

Particle identification (1)

5

• The ALICE experiment employs all known techniques for hadron identification:

• dE/dx in ITS, for very low-momenta tracks (pT ≈ 100 MeV/c), σ ≈ 10-15%

• dE/dx in TPC, at low and very high momenta (rel. rise), σ ≈ 5.2% (pp) -> 6.5% (Pb-Pb central)

• Time-Of-Flight, intermediate pT,σ ≈ 85 ps (Pb-Pb) -> 120 ps (pp)

• HMPID, Cerenkov radiation

2012-OCT-09 | alexander.philipp.kalweit@cern.ch

Particle identification (1)

5

• The ALICE experiment employs all known techniques for hadron identification:

• dE/dx in ITS, for very low-momenta tracks (pT ≈ 100 MeV/c), σ ≈ 10-15%

• dE/dx in TPC, at low and very high momenta (rel. rise), σ ≈ 5.2% (pp) -> 6.5% (Pb-Pb central)

• Time-Of-Flight, intermediate pT,σ ≈ 85 ps (Pb-Pb) -> 120 ps (pp)

• HMPID, Cerenkov radiation

2012-OCT-09 | alexander.philipp.kalweit@cern.ch

Particle identification (1)

5

• The ALICE experiment employs all known techniques for hadron identification:

• dE/dx in ITS, for very low-momenta tracks (pT ≈ 100 MeV/c), σ ≈ 10-15%

• dE/dx in TPC, at low and very high momenta (rel. rise), σ ≈ 5.2% (pp) -> 6.5% (Pb-Pb central)

• Time-Of-Flight, intermediate pT,σ ≈ 85 ps (Pb-Pb) -> 120 ps (pp)

• HMPID, Cerenkov radiation

2012-OCT-09 | alexander.philipp.kalweit@cern.ch

Particle identification (1)

5

• The ALICE experiment employs all known techniques for hadron identification:

• dE/dx in ITS, for very low-momenta tracks (pT ≈ 100 MeV/c), σ ≈ 10-15%

• dE/dx in TPC, at low and very high momenta (rel. rise), σ ≈ 5.2% (pp) -> 6.5% (Pb-Pb central)

• Time-Of-Flight, intermediate pT,σ ≈ 85 ps (Pb-Pb) -> 120 ps (pp)

• HMPID, Cerenkov radiation

2012-OCT-09 | alexander.philipp.kalweit@cern.ch

Particle identification (1)

5

• The ALICE experiment employs all known techniques for hadron identification:

• dE/dx in ITS, for very low-momenta tracks (pT ≈ 100 MeV/c), σ ≈ 10-15%

• dE/dx in TPC, at low and very high momenta (rel. rise), σ ≈ 5.2% (pp) -> 6.5% (Pb-Pb central)

• Time-Of-Flight, intermediate pT,σ ≈ 85 ps (Pb-Pb) -> 120 ps (pp)

• HMPID, Cerenkov radiation

2012-OCT-09 | alexander.philipp.kalweit@cern.ch

Particle identification (1)

5

• The ALICE experiment employs all known techniques for hadron identification:

• dE/dx in ITS, for very low-momenta tracks (pT ≈ 100 MeV/c), σ ≈ 10-15%

• dE/dx in TPC, at low and very high momenta (rel. rise), σ ≈ 5.2% (pp) -> 6.5% (Pb-Pb central)

• Time-Of-Flight, intermediate pT,σ ≈ 85 ps (Pb-Pb) -> 120 ps (pp)

• HMPID, Cerenkov radiation

2012-OCT-09 | alexander.philipp.kalweit@cern.ch

Particle identification (1)

5

• The ALICE experiment employs all known techniques for hadron identification:

• dE/dx in ITS, for very low-momenta tracks (pT ≈ 100 MeV/c), σ ≈ 10-15%

• dE/dx in TPC, at low and very high momenta (rel. rise), σ ≈ 5.2% (pp) -> 6.5% (Pb-Pb central)

• Time-Of-Flight, intermediate pT,σ ≈ 85 ps (Pb-Pb) -> 120 ps (pp)

• HMPID, Cerenkov radiation

2012-OCT-09 | alexander.philipp.kalweit@cern.ch

Particle identification (1)

5

• The ALICE experiment employs all known techniques for hadron identification:

• dE/dx in ITS, for very low-momenta tracks (pT ≈ 100 MeV/c), σ ≈ 10-15%

• dE/dx in TPC, at low and very high momenta (rel. rise), σ ≈ 5.2% (pp) -> 6.5% (Pb-Pb central)

• Time-Of-Flight, intermediate pT,σ ≈ 85 ps (Pb-Pb) -> 120 ps (pp)

• HMPID, Cerenkov radiation

2012-OCT-09 | alexander.philipp.kalweit@cern.ch

Particle identification (2)• Unique speciality of the ALICE experiment:

continuous and precise particle identification and tracking from very low (100 MeV/c) to very hight pT (20 GeV/c).

• Identification from the lightest (electron) to the heaviest (anti-nuclei) particles:

6

(GeV/c)zp0.1 0.2 1 2 3 4 5

TP

C io

niz

atio

n s

ign

al (

a.u

.)

0

100

200

300

400

500

600

700

800

900

1000He4

td

p

-K

-

-e

offlinetrigger

0.3

He3

= 2.76 TeVNNsPb-Pb, 2011 run,

negative particles,

, 2012July 4th

ALI-PERF-27141

Hadron chemistry

2012-OCT-09 | Quark Confinement and the Hadron Spectrum Conference -- Munich

2012-OCT-09 | alexander.philipp.kalweit@cern.ch

Low-pT particle production: π/K/p (1)

• Excellent PID allows direct measurement of pion, kaon, and proton spectra at low momenta.

• Spectral shape: hydrodynamics.• large radial flow: <βT> = 0.65 ± 0.02

~10% higher w.r.t. RHIC• Hydro (with refined late fireball

description works) at the LHC.

• Production yields: thermal models.

8

arXiv:1208.1974 [hep-ex]

2012-OCT-09 | alexander.philipp.kalweit@cern.ch

Low-pT particle production: π/K/p (2)

• Comparison to thermal model prediction: good agreement, but proton yield is lower in data. A similar behavior is seen in the analysis of pp data.

9

Predicted temperature T=164 MeVA.Andronic, P.Braun-Munzinger, J.Stachel NP A772 167

...more details in the next talk.

2012-OCT-09 | alexander.philipp.kalweit@cern.ch

Low-pT particle production: π/K/p (2)

• Comparison to thermal model prediction: good agreement, but proton yield is lower in data. A similar behavior is seen in the analysis of pp data.

9

Predicted temperature T=164 MeVA.Andronic, P.Braun-Munzinger, J.Stachel NP A772 167

...more details in the next talk.

(GeV/c)t

p0 0.5 1 1.5 2 2.5

-1 |

y|<

0.5

(G

eV

/c)

t d

N/d

pIN

EL

1/N

-310

-210

-110

1

10ALICE preliminary

= 7 TeVspp at

2+stat2syserror =

Levy fit

+π

+K

p

Normaliztion Error 8.3%

pp@7TeV

2012-OCT-09 | alexander.philipp.kalweit@cern.ch

Low-pT particle production: π/K/p (2)

• Comparison to thermal model prediction: good agreement, but proton yield is lower in data. A similar behavior is seen in the analysis of pp data.

9

Predicted temperature T=164 MeVA.Andronic, P.Braun-Munzinger, J.Stachel NP A772 167

...more details in the next talk.

(GeV/c)t

p0 0.5 1 1.5 2 2.5

-1 |

y|<

0.5

(G

eV

/c)

t d

N/d

pIN

EL

1/N

-310

-210

-110

1

10ALICE preliminary

= 7 TeVspp at

2+stat2syserror =

Levy fit

+π

+K

p

Normaliztion Error 8.3%

pp@7TeV

pp K p

par

ticle

ratio

-510

-410

-310

-210

-110

1

ALICE data pp 7TeV (prel.)

T = 154 MeV

= 1.66 fmC MeV / R-3 = 3 10B

= 1 fm / T = 170 MeVCR

= 2 fm / T = 170 MeVCR

THERMUS

Preliminary

Thermus: S. Wheaton, J. Cleymans and M. Hauer, Comput. Phys. Commun. 180 (2009) 84-106

Anti-matter

2012-OCT-09 | Quark Confinement and the Hadron Spectrum Conference -- Munich

2012-OCT-09 | alexander.philipp.kalweit@cern.ch

Table of nuclides

• Decades of research in nuclear physics have explored the table of nuclides from the valley of stability to its boundaries and the heaviest elements.

• In high energy nuclear physics experiments like ALICE, we have the unique possibility to study also the production of the corresponding anti-nuclei in ppand - in particular - PbPbcollisions.

• Compared to e.g. π, K, p these particles are only rarely produced and the production probabilitydecreases quickly with increasing mass...

11

2012-OCT-09 | alexander.philipp.kalweit@cern.ch

Light anti-nuclei

• Unique experimental possibilities at the LHC: matter and anti-matter are produced in equal amount:

12

arXiv:1208.1974 [hep-ex]

2012-OCT-09 | alexander.philipp.kalweit@cern.ch

Light anti-nuclei

• Unique experimental possibilities at the LHC: matter and anti-matter are produced in equal amount:

12

2012-OCT-09 | alexander.philipp.kalweit@cern.ch

Observation of anti-alpha

• Powerful combination of dE/dx and time-of-flight measurements: clean identification of deuterons, tritons, 3He, and 4He.

• First observation by STAR:Nature 473 (2011) 353-356

• Significant increase instatistics w.r.t. to the 2010Pb-Pb run: 10 clearly identified candidates compared to 4.

• Extraction of yield isongoing, but correction forabsorption of anti-matter in detector material remains challenging.

13

Search for exotic hyper-matter states

2012-OCT-09 | Quark Confinement and the Hadron Spectrum Conference -- Munich

2012-OCT-09 | alexander.philipp.kalweit@cern.ch

(Anti-)Hyper-Matter

• By replacing a baryon with a hyperon, the table of nuclides can be extended in another dimension:

• N.B: basic properties of these particles, e.g. lifetime and decay topology are very similar to the one of Λs etc. (classical V0s and cascades).

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2012-OCT-09 | alexander.philipp.kalweit@cern.ch

The hyper-triton

• The lightest known hyper-nucleus. Signal from 2011 Pb-Pb run.• Currently working on pT-spectra extraction.

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2012-OCT-09 | alexander.philipp.kalweit@cern.ch

H-Dibaryon and Lambda-neutron bound state• Are there even lighter hyper-nuclei systems?

• Λ-Λ bound state might exist: H-Dibaryon.• Experimental signature of a Λn bound state in the HypHI-experiment at GSI.

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2012-OCT-09 | alexander.philipp.kalweit@cern.ch

Search for a Lambda-neutron bound state (1)

• If it existed, what would be the expected yield in ALICE at the LHC?

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BRefficiencyfrom fullsimulation

yield from thermal model

2012-OCT-09 | alexander.philipp.kalweit@cern.ch

Search for a Lambda-neutron bound state (2)

• But no visible signal in real data...

• From the non observation we can set an upper limit:

dN/dy < 1.5x10-3 (99% CL)

• For illustration: this is a factor 10 lower than the expectation from the thermal model.

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2012-OCT-09 | alexander.philipp.kalweit@cern.ch

H-Dibaryon

• First predicted by Jaffe with a bag model calculation (Jaffe, PRL 38, 617 (1977)) and revisited by recent lattice calculations (Inoue et al., PRL 106, 162001 (2011) and Beane et al., PRL 106, 162002 (2011)).

• Similar study as for the Lambda-neutron bound state. Also here no visible signal. Upper limit:

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For a strongly bound H: dN/dy < 8.4x10-4 (99% CL)

For a lightly bound H: dN/dy < 2x10-4 (99% CL)

2012-OCT-09 | alexander.philipp.kalweit@cern.ch

Summary

• ALICE’s unique particle identification capabilities allow for a very precise and detailed study of low momentum (bulk) particle production at the LHC.

• The particle production is found to be in agreement with hydrodynamical and thermal model calculations. However, late fireball descriptions have to be included in the hydro-codes and the observed proton yield is lower than the expectation.

• The LHC offers unique experimental possibilities for the measurement of known and the search for unknown anti- and hyper-matter states.

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2012-OCT-09 | alexander.philipp.kalweit@cern.ch

Outlook: p-A pilot run in September

• Early next year: p-A run for the measurement of cold nuclear matter effects.

• 13th of September: very successful pilot run (one night) at much lower luminosity

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ALICE pA collision 5.02 TeV

BACKUP SLIDES

2012-OCT-09 | Quark Confinement and the Hadron Spectrum Conference -- Munich

2012-OCT-09 | alexander.philipp.kalweit@cern.ch

Non-equilibrium models

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