Hadron Physics• QCD: are we satisfied with it?

• Antiproton’s potentiality

• The PANDA enterprise1

Paola Gianotti

Our present knowledge of matter is the result of centuries of studies…

Philosophers of ancient Greece believed it was made of 4 elements

what is matter made of?what is matter made of?

Mendeleev 1869 introduced the periodic table of elements1808 Dalton, following

their weights, make a first list of elements1963 Murray, Gell-Mann, and Zweig

laid the foundation of quark model

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Quantum ChromodynamicsQuantum Chromodynamics

The QCD Lagrangian is, in principle, a complete description of the strong interaction. There is just one overall coupling constant g , and six quark-mass parameters mj for the six quark flavors

But, it leads to equations that are hard to solve

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Furthermore, we've never seen particles carrying fractional electric charge, which we nonetheless ascribe to the quarks.

And certainly we haven't seen anything like gluons--massless particles mediating long-range strong forces.

The ConfinementThe Confinement

So if QCD is to describe the world, it must explain why quarks and gluons cannot exist as isolated particles. That is the so-called confinement problem.

None of the particles that we've actually seen appear in the formula and none of the particles that appear in the formula has ever been observed.

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Hadron massesHadron massesThe elementary particles of the Standard Model gain their mass through the Higgs mechanism.However, only a few percent of the mass of the proton is due to the Higgs mechanism. The rest is created in an unknown way by the strong interaction.

Glueballs would be massless without the strong interaction and their predicted masses arise solely from the strong interaction.

C. Morningstar and M. Peardon, Phys. Rev. D 60, 034509 (1999)

The possibility to study a whole spectrum of glueballs might thereforebe the key of understanding the mechanism of mass creation by the strong interaction.

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The chiral symmetryThe chiral symmetry

There is another qualitative difference between the observed reality and the world of quarks and gluons.

The phenomenology indicates that if QCD is to describe the world, then the u and d quarks must have very small masses.

But if u and d quarks have very small masses, then the equations of QCD possess some additional symmetry, called chiral symmetry.

There is no such symmetry among the observed strongly interacting particles; they do not come in opposite-parity pairs. So if QCD is to describe the real world, the chiral symmetry must be spontaneously broken.

and this mechanism is playing an important role in the process of mass generation

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Chiral Chiral symmetry symmetry restorationrestoration

The mass of light hadrons (u,d,(s)) is dominated by spontaneous chiral symmetry breaking.

In the nuclear medium (ρ>0) we can restore, at least partially this symmetry.

Hints of this effect have been already observed. We wants to extend these studies to Charmed mesons

pionic atoms

KAOS/FOPI

HESR

π

K

D

vacuum nuclear mediumρ = ρ0

π+

π-

K-

K+

D+

D-

25 MeV

100 MeV

50 MeV

Mass modifications of mesons

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How do we solve QCD problems?How do we solve QCD problems?

The first approach is to try to solve the equations. That's not easy. Fortunately, powerful modern computers have made it possible to calculate a few of the key predictions of QCD directly.

The agreement with the measured masses is at the 10% level.

The second approach is that of creating phenomenological models that are simpler to deal with, but still bear some significant resemblance to the real thing.

arXiv:hep-lat/9904012v1

quark antiqark

Meson

Hybrid

Glueball8

Nowadays, QCD prediction can reach precisions at the GeV around 10 %, and also the phenomenological models are not doing better!Can we be satisfied of this accuracy?

Can we be satisfied?Can we be satisfied?

Just a note: the Tolemaic system allowed to predict the positions of the planets with the same level of accuracy…..

but it was wrong! 9

Experimental tests are needed…Experimental tests are needed…High statistics and high quality data are necessary to help constraining the models

Different experimental techniques can be used to focus on different aspects:

• The selection of special working conditions or of final states helps filtering initial/final state quantum numbers;

• In protons-antiproton annihilations complex objects collide

• The interaction occurs between two beams of (anti)quarks and gluons

p

p

pe-

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High Energy: pp-Colliders (CERN, Fermilab)

Discovery of Z0, W±

Discovery of t-quark

High Energy: pp-Colliders (CERN, Fermilab)

Discovery of Z0, W±

Discovery of t-quark

Medium Energy: Conventional p-beams (LBL, BNL, CERN, Fermilab, KEK, ...) p-Storage Rings (LEAR (CERN); Antiproton Accumulator (Fermilab))

Meson Spectroscopy (u, d, s, c)p-nucleus interactionHypernucleiAntihydrogen first productionCP-violation

Medium Energy: Conventional p-beams (LBL, BNL, CERN, Fermilab, KEK, ...) p-Storage Rings (LEAR (CERN); Antiproton Accumulator (Fermilab))

Meson Spectroscopy (u, d, s, c)p-nucleus interactionHypernucleiAntihydrogen first productionCP-violation

Low Energy (Stopped p‘s): Conventional p-beams p-Storage Rings (LEAR, AD (CERN))

p-Atoms (pHe)p/p-mass ratioAntihydrogen

Low Energy (Stopped p‘s): Conventional p-beams p-Storage Rings (LEAR, AD (CERN))

p-Atoms (pHe)p/p-mass ratioAntihydrogen

Physics with antiprotons had a great pastPhysics with antiprotons had a great past

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Physics with antiprotons have a great futurePhysics with antiprotons have a great future

High Energy: pp-Collider (Fermilab)

B physics, Top, Electroweak, QCD, Higgs

High Energy: pp-Collider (Fermilab)

B physics, Top, Electroweak, QCD, Higgs

Medium Energy: Conventional p-beams (Fermilab, (KEK), ...) p-Storage Rings (HESR, (Fermilab))

Charmonium spectroscopyExotic searchD physicsBaryon spectroscopyHypernucleiCP-violation

Medium Energy: Conventional p-beams (Fermilab, (KEK), ...) p-Storage Rings (HESR, (Fermilab))

Charmonium spectroscopyExotic searchD physicsBaryon spectroscopyHypernucleiCP-violation

Low Energy (Stopped p‘s): Conventional p-beams p-Storage Rings (FLAIR, AD (CERN))

p-Atoms Antihydrogen spectroscopy

Low Energy (Stopped p‘s): Conventional p-beams p-Storage Rings (FLAIR, AD (CERN))

p-Atoms Antihydrogen spectroscopy 12

Spectroscopy studies

Production

all JPC available

Exotic states are produced with rates similar to qq conventional systems

All ordinary quantum numbers can be reached σ ~1 μb

All ordinary quantum numbers can be reached σ ~1 μb

p

p_

G

M

p

M

H

p_

p

M

H

p_

Even exotic quantum numbers can be reached σ ~100 pb

Even exotic quantum numbers can be reached σ ~100 pb

Two are the mechanisms to access particular final states:

Formation

only selected JPC

p

p_

p

p_

H

p

p_

HG

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In the light meson region, about 10 states have been classified as “Exotics”. Almost all of them have been seen in pp...

Exotic hadronsExotic hadrons

Main non-qq candidates

f0(980) 4q state - molecule

f0(1500) 0++ glueball candidate

f0(1370) 0++ glueball candidate

f0(1710) 0++ glueball candidate

(1410); (1460) 0+ glueball candidate

f1(1420) hybrid, 4q state

1(1400) hybrid candidate 1

1(1600) hybrid candidate 1

(1800) hibrid candidate 0

2(1900) hybrid candidate 2

1(2000) hybrid candidate 1

a2’(2100) hybrid candidate 1++ 14

Charmonium regionCharmonium region

From G. S. Bali, Int.J.Mod.Phys. A21 (2006) 5610-5617

arXiv:hep-lat/0608004

Only with high statistics and different final states, quantum number assignment become clear

Charmonium spectrum, glueballs, spin-exotics cc-glue hybrids with experimental results

Charmonium spectrum, glueballs, spin-exotics cc-glue hybrids with experimental results

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Antiproton’s power Antiproton’s power

3500 3520 MeV3510C

Ball

ev./

2 M

eV

100

ECM

CBallE835

1000

E 8

35

ev./

pb

c1

e+e→’→ 1,2

→ e+e→ J

e+e interactions:

- Only 1 states are formed- Other states only by secondary decays (moderate mass resolution)

- All states directly formed (very good mass resolution)

→ J→ e+e

p p→ 1,2

_

pp reactions:_

Br(e+e →·Br( → c) = 2.5 Br( )pp → c = 1.2 _

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p-beams can be cooled Excellent resonance resolutionAntiproton’s power Antiproton’s power

bBW EEEdEfL )(),(0

The resonance mass MR, total width R and product of branching ratios into the initial and final state BinBout can be extracted by measuring the formation rate for that resonance as a function of the cm energy E.

The production rate of a certain final state is a convolution of theBW cross section and the beam energy distribution function f(E,E):

Measured rate

Beam

Resonance cross

section

CM Energy

Crystal Ball: typical resolution ~ 10 MeV

Fermilab: 240 keV

PANDA: ~30 keV

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The hadron’s structureThe hadron’s structureThe characteristics hadrons are given only in minor part by the constituent quarks.Quarks and gluons dynamics plays a fundamental role in the definitions of hadron’s properties: mass, spin, etc…

Nucleon Form Factors have been mainly studied using electromagnetic probes, but the physical diagrams can be reverted… and a complementary approach can be used

Generalized Parton Distributions functions (GPDs) contain both the usual form factors and parton distributions, but in addition they include correlations between states of different longitudinal and transverse momenta. GPDs give a three-dimensional picture of the nucleon.

In a similar way Deeply Virtual Compton Scattering (DVCS) can be crossed-studied

perturbative QCDnon-perturbative QCD18

0 2 4 6 8 12 1510p Momentum [GeV/c]

Mass [GeV/c2]

1 2 3 4 5 6

ΛΛΣΣΞΞ

ΛcΛc

ΣcΣc

ΞcΞc

ΩcΩcΩΩ DDDsDs

qqqq ccqq

nng,ssg ccg

ggg,gg

light qqπ,ρ,ω,f2,K,K*

ccJ/ψ, ηc, χcJ

nng,ssg ccg

ggg

Our PlaygroundOur Playground

Meson spectroscopy• light mesons• charmonium• exotic states

− glueballs− hybrids− molecules/multiquarks

• open charm

Baryon/antibaryon production

Charm in nuclei

Hypernuclei

Em. form factors of the proton

Generalized Parton Distributions19

Production Rates (1-2 (fb)Production Rates (1-2 (fb)-1-1/y)/y)Final StateFinal State cross sectioncross section # rec. events/y# rec. events/y

Key elements : Low multiplicity events Possibility to trigger on defined final states

Key elements : Low multiplicity events Possibility to trigger on defined final states

mbpp

nb

nb

nbJ

nbeeJ

nbDD

bA

b

nbKK

T

cc

cc

Sc

70)(

101.0

1020

107.3)/(

10630),(/

103)3770(

)10(102)(

1050

1010

5

7

72

9––

7

58

10

70

20

below DD threshold• all the predicted states have been detected,

but• there is lack of precise measurements of masses, widths and branching ratios(i.e. c, c(2S), hc)

Charmonium spectroscopyCharmonium spectroscopyCharmonium energy is the transition range between perturbative and non-perturbative regime. It is the energy range where models are tuned

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Charmonium above DD thresholdCharmonium above DD thresholdThis is the more obscure region: old and new measurements at electron machines seem not in agreement.

On the other side several new states showed up at the B-factories

for most states JPC is not well established…and 23

Newly-bornNewly-bornnew Charmonium-like states from Bellenew Charmonium-like states from Belle

Y(4361)

Y(4664)Z(4430) →ψ(2S)π±

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Open charm statesOpen charm states• Open charm sates are the QCD

analogon of hydrogen atom for QED

• Narrow states Ds0(2317) andDs1 (2458) recently discovered at B-factories do not fit theoretical calculations.

• Quantum numbers for the newest states DsJ(2700) and DsJ

(2880) are open

• At full luminosity at p momenta larger than 6.4 GeV/c PANDA will produce large numbers of DD pairs.

• Despite small signal/background ratio (510-6) background situation favourable because of limited phase space for additional hadrons in the same process. 25

By making an energy scan around threshold → counting signal events, determine the excitation function and extract the width

An example…An example…

thresholdDs*Ds0*

• The width of Ds0*(2317) can be measured in the reaction ppDsDs0*(2317)

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: the new antiproton facility: the new antiproton facility

Primary Beams

•1012/s; 1.5 GeV/u; 238U28+

•Factor 100-1000 present in intensity•2(4)x1013/s 30 GeV protons•1010/s 238U73+ up to 25 (- 35) GeV/u

Secondary Beams

•Broad range of radioactive beams up to 1.5 - 2 GeV/u; up to factor 10 000 in intensity over present •Antiprotons 3 (0) - 30 GeV

Storage and Cooler Rings•Radioactive beams•e – A collider•1011 stored and cooled 0.8 - 14.5 GeV antiprotons

•Cooled beams•Rapidly cycling superconducting magnets

Key Technical Features

Facility for AntiprotonFacility for Antiprotonand Ion Researchand Ion Research

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HESR - High Energy Storage Ring HESR - High Energy Storage Ring

High luminosity mode

High resolution mode

• p/p ~ 10 (electron cooling)• Lumin. = 1031 cm s

• Lumin. = 2 x 1032 cm s • p/p ~ 10 (stochastic cooling)

• Production rate 2x107/sec

• Pbeam = 1 - 15 GeV/c

• Nstored = 5x1010 p

• Internal Target

_

from RESR

Pellet-Target H2 (ρ=0.08 g/cm2)70000 pellets/s p

2p HΔT ρ d

d = 1 mm

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Detector requirements:

• nearly 4 solid angle (partial wave analysis)• high rate capability (2·107 annihilations/s)• good PID (, e, , , K, p)• momentum resolution (~1%)• vertex info for D, K0

S, (c = 317 m for D±)• efficient trigger (e, , K, D, )• modular design (Hypernuclei experiments)

General Purpose DetectorGeneral Purpose Detector

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Pellet or cluster-jet targetPellet or cluster-jet target

2T Superconducting solenoidfor high pt particles 2T Superconducting solenoidfor high pt particles

2Tm Dipole for forward tracks2Tm Dipole for forward tracks30

Silicon Microvertex detectorSilicon Microvertex detector

Central TrackerCentral Tracker

Forward ChambersForward Chambers31

Barrel DIRCBarrel DIRCBarrel TOFBarrel TOF

Endcap DIRCEndcap DIRC Forward TOFForward TOF

Forward RICHForward RICH

Muon DetectorsMuon Detectors

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PWO EMCPWO EMC Forward Shashlyk EMCForward Shashlyk EMC Hadron CalorimeterHadron Calorimeter33

Collaboration

• At present a group of 420 physicists from 55 institutions of 17 countries

Basel, Beijing, Bochum, IIT Bombay, Bonn, Brescia, IFIN Bucharest, Catania, Cracow, IFJ PAN Cracow, Cracow UT, Dresden, Edinburgh,

Erlangen, Ferrara, Frankfurt, Genova, Giessen, Glasgow, GSI, Inst. of Physics Helsinki, FZ Jülich, JINR Dubna, Katowice, KVI Groningen, Lanzhou, LNF, Lund, Mainz, Minsk, ITEP Moscow, MPEI Moscow,

TU München, Münster, Northwestern, BINP Novosibirsk, IPN Orsay, Pavia, Piemonte Orientale, IHEP Protvino, PNPI St.Petersburg,

KTH Stockholm, Stockholm, INFN Torino, Torino, Torino Politecnico, Trieste, TSL Uppsala, Tübingen, Uppsala, Valencia, SINS Warsaw, TU

Warsaw, SMI Wien

Basel, Beijing, Bochum, IIT Bombay, Bonn, Brescia, IFIN Bucharest, Catania, Cracow, IFJ PAN Cracow, Cracow UT, Dresden, Edinburgh,

Erlangen, Ferrara, Frankfurt, Genova, Giessen, Glasgow, GSI, Inst. of Physics Helsinki, FZ Jülich, JINR Dubna, Katowice, KVI Groningen, Lanzhou, LNF, Lund, Mainz, Minsk, ITEP Moscow, MPEI Moscow,

TU München, Münster, Northwestern, BINP Novosibirsk, IPN Orsay, Pavia, Piemonte Orientale, IHEP Protvino, PNPI St.Petersburg,

KTH Stockholm, Stockholm, INFN Torino, Torino, Torino Politecnico, Trieste, TSL Uppsala, Tübingen, Uppsala, Valencia, SINS Warsaw, TU

Warsaw, SMI Wien

http://www.gsi.de/panda

Austria – Belaruz - China - Finland - France - Germany – India - Italy – The Nederlands - Poland – Romania - Russia – Spain - Sweden – Switzerland - U.K. – U.S.A..

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SummarySummary

perform high resolution spectroscopy with p-beam in formation experiments:E ≈ Ebeam

produce, with high yields, gluonic excitations: glueballs, hybrids, multi-quark states ≈ 100 pb

study partial chiral symmetry restoration by implanting mesons inside the nuclear medium

produce hyperon-antihyperon taggable beams

perform high resolution spectroscopy with p-beam in formation experiments:E ≈ Ebeam

produce, with high yields, gluonic excitations: glueballs, hybrids, multi-quark states ≈ 100 pb

study partial chiral symmetry restoration by implanting mesons inside the nuclear medium

produce hyperon-antihyperon taggable beams

Thanks to the new HESR antiproton ring at FAIR we will be able to...

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Space: The final frontier…

In the Star Trek universe, spaceships use the enormous energy of matter-antimatter annihilation to leap across the universe.

This is science fiction, but antiproton-proton annihilation is not36

A new challenging Enterprise is started!If you are interested….Jump on!

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