Experimental Study of the Strong Interaction at FAIR · Experimental Study of Charmonium e+e-annihilation • Direct formation only possible for JPC = 1--states. • All other states

Experimental Study of the Strong Interaction at FAIR

Diego BettoniIstituto Nazionale di Fisica Nucleare, Ferrara

Lattice 2007Regensburg, 31 July 2007

D. Bettoni Physics at FAIR 2

Outline• FAIR• HESR• PANDA Physics Program

– Charmonium Spectroscopy– Hybrids and Glueballs– Hadrons in Nuclear Matter– Hypernuclear Physics– Timelike Proton Form Factors

• The PANDA Detector• PAX Physics Program

– Transversity in Polarized Deep Inelastic Scattering– Single Spin Asymmetries– Timelike Proton Form Factors

• The PAX Detector Concept• Conclusions


FAIR at a glance


The FAIR Complex

Antiprotonproduction

100 TmSynchrotron

SIS100

Collector & CoolerRing

AccumulatorRing

Deceleration

Rare isotopeProduction &

separator

HighEnergy

Storage Ring

HESR&

PANDA

NewExperimentalStorage Ring

CompressedBarionicMatter

experiment

NESR

300 TmStretcher

Ring

SIS300

From existing GSIUNILAC & SIS18& new proton linac

+ Experiments:E-I colliderNuclear PhysicsAtomic PhysicsPlasma PhysicsApplied Physics


Technical Realization of FAIR

100 m

UNILACSIS 18

SIS 100/300

HESR

SuperFRS

NESR

CR

RESR

FLAIR

Accelerator Components & Key CharacteristicsRing/Device Beam Energy Intensity

SIS100 (100Tm) protons 30 GeV 4x1013

238U 1 GeV/u 5x1011

(intensity factor 100 over present)

SIS300 (300Tm) 40Ar 45 GeV/u 2x109

238U 34 GeV/u 2x1010

CR/RESR/NESR ion and antiproton storage and experiment rings

HESR antiprotons 14 GeV ~1011

Super-FRS rare-isotope beams 1 GeV/u <109

Radioactive Ion Production Target

Anti-Proton Production Target

Existing facility: provides ion-beam source and injector for FAIR

Existing facility: provides ion-beam source and injector for FAIR

New future facility: provides ion and anti-matterbeams of highest-intensity and up to high energies

New future facility: provides ion and anti-matterbeams of highest-intensity and up to high energies

Technical Realization of FAIR


Beam Intensity:- primary heavy-ion beam intensity increases by x 100 – x 1000- secondary beam intensity increases by up to x 10000

Beam Energy:- heavy-ion energy : x 30

Beam Variety:- antiprotons - protons to uranium & radioactive ion beams

Beam Precision:- cooled antiproton beams- intense cooled radioactive ion beams

Beam Pulse structure:- optimized for experiments: from dc to 50 ns

Parallel Operation:- full accelerator performance for up to four different and independent experiments and experimental programs

Unprecedented System Parameters at FAIR


High luminosity mode

High resolution mode

• Production rate 2x107/sec

• Pbeam = 1 - 15 GeV/c

• Nstored = 5x1010 p

• Internal Target

_

• δp/p ~ 10−5 (electron cooling)• Lumin. = 1031 cm−2 s−1

• Lumin. = 2 x 1032 cm−2 s−1

• δp/p ~ 10−4 (stochastic cooling)

High-Energy Storage Ring

PANDA


Antiproton Physics Program

• Charmonium Spectroscopy. Precision measurement of masses, widths and branching ratios of all (c⎯c) states (hydrogen atom of QCD).

• Search for gluonic excitations (hybrids, glueballs) in the charmonium mass range (3-5 GeV/c2).

• Search for modifications of meson properties in the nuclear medium, and their possible relation to the partial restoration of chiral symmetry for light quarks.

• Precision γ-ray spectroscopy of single and double hypernuclei, to extract information on their structure and on the hyperon-nucleon and hyperon-hyperon interaction.

• Electromagnetic processes (DVCS, D-Y, FF ...) , open charm physics


QCD Systems to be studied in Panda


Charmonium Spectroscopy

Charmonium is a powerful tool for theunderstanding of the strong interaction.The high mass of the c quark (mc ~ 1.5GeV/c2) makes it plausible to attempt a

description of the dynamical properties ofthe (c⎯c) system in terms of non relativistic

potential models, in which the functionalform of the potential is chosen to reproduce

the known asymptotic properties of thestrong interaction. The free parameters in

these models are determined from acomparison with experimental data.

Non-relativistic potential models +Relativistic corrections + PQCD + LQCD

β2 ≈ 0.2 αs ≈ 0.3


Experimental Study of Charmonium

e+e- annihilation• Direct formation only possible for

JPC = 1-- states.• All other states must be produced

via radiative decays of the vector states, or via two-photon processes, ISR, B-decay, double charmonium.

Good mass and width resolution for the vector states. For the other statesmodest resolutions (detector-limited).

In general, the measurement of In general, the measurement of subsub--MeV widths not possible in eMeV widths not possible in e++ee--..

⎯pp annihilation• Direct formation possible for all

quantum numbers.•• Excellent measurement of masses Excellent measurement of masses

and widths for all states, given by and widths for all states, given by beam energy resolution and not beam energy resolution and not detectordetector--limitedlimited.


Experimental Method in ⎯pp Annihilation

( ) 4/412

22

2

2RR

RoutinBW ME

BBk

JΓ+−

Γ+=

πσ

The cross section for the process:⎯pp →⎯cc → final state

is given by the Breit-Wigner formula:

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

∫ +Δ= bBW EEEdEfL σσεν )(),(0

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


Example: χc1 and χc2 scans in Fermilab E835

χ1

χ2


χc1 and χc2 masses and widths

χc1 E835E835 E760E760

M(MeV/c2) 3510.719 ± 0.051 ± 0.019 3510.60 ± 0.09 ± 0.02

Γ(MeV) 0.876 ± 0.045 ± 0.026 0.87 ± 0.11 ± 0.08

B(p⎯p)Γ(J/ψγ)(eV) 21.5 ± 0.5 ± 0.6 ± 0.6 21.4 ± 1.5 ± 2.2

χc2 E835E835 E760E760

M(MeV/c2) 3556.173 ± 0.123 ± 0.020 3556.22 ± 0.13 ± 0.02

Γ(MeV) 1.915 ± 0.188 ± 0.013 1.96 ± 0.17 ± 0.07

B(p⎯p)Γ(J/ψγ)(eV) 27.0 ± 1.5 ± 0.8 ± 0.7 27.7 ± 1.5 ± 2.0

χ1 χ2


The ηc(11S0) Mass

M(ηc) = 2980.4 ± 1.2 MeV/c2

Experiment Mass (MeV/c2)CLEO 2981.8 ± 1.3 ± 1.5BaBar 2982.5 ± 1.1 ± 0.9E835 2984.1 ± 2.1 ± 1.0BES 2977.5 ± 1.0 ± 1.2Belle 2979.6 ± 2.3 ± 1.6BES 2976.3 ± 2.3 ± 1.2Mark III 2969 ± 4 ± 4Crystal Ball 2984± 2.3 ± 4

PDG 2006


The ηc(11S0) Total Width

Γ(ηc) = 25.5 ± 3.4 MeV

PDG 2006

Experiment Width (MeV)CLEO 24.8 ± 3.4 ± 3.5BaBar 34.3 ± 2.3 ± 0.9E835 20.4+7.7

-6-7 ± 2.0BES 17.0 ± 3.7 ± 7.4Belle 29 ± 8 ± 6BES 11.0 ± 8.1 ± 4.1E760 23.9+12.6

-7.1

R704 7.0+7.5-7.0

Mark III 10.1+33.0-8.2

Crystal Ball 11.5 ± 4.5


The ηc(21S0)

BaBar

PDG 2006M(ηc′) = 3638 ± 4 MeV/c2

Γ(η′c) = 14 ± 7 MeV

Belle


The hc(11P1)0

c /Jhpp πψ +→→

E760

E835

γηcch →2/4.06.04.3524)( cMeVhM c ±±=

CLEOe+e- →ψ′→π0hchc →ηcγ ηc→hadrons

M(E835)=3525.8±0.2±0.2 MeV/c2


Charmonium States abovethe D⎯D threshold

The energy region above the D⎯Dthreshold at 3.73 GeV is very poorlyknown. Yet this region is rich in newphysics.• The structures and the higher vector

states (ψ(3S), ψ(4S), ψ(5S) ...) observed by the early e+e-experiments have not all been confirmed by the latest, much more accurate measurements by BES.

• This is the region where the first radial excitations of the singlet and triplet Pstates are expected to exist.

• It is in this region that the narrow D-states occur.


The D wave states

• The charmonium “D states”are above the open charm threshold (3730 MeV ) but the widths of the J= 2 states

and are expected to be small:

DDD →23,1

forbidden by parity conservation*

23,1 DDD → forbidden by energy conservation

21D2

3D

Only the ψ(3770), considered to be largely 3D1 state, has been clearlyobserved. It is a wide resonance (Γ(ψ(3770)) = 25.3 ± 2.9 MeV) decayingpredominantly to D⎯D. A recent observation by BES of the J/ψπ+π- decaymode was not confirmed by CLEO-c.


New States above D⎯D threshold

Y(3940)→J/ψω

ee→J/ψ X(3940)

γγ→χc2’

)2) (GeV/cψJ/-π+πm(3.8 4 4.2 4.4 4.6 4.8 5

2E

vent

s / 2

0 M

eV/c

0

10

20

30

40

)2) (GeV/cψJ/-π+πm(3.8 4 4.2 4.4 4.6 4.8 5

2E

vent

s / 2

0 M

eV/c

0

10

20

30

40

)2) (GeV/cψJ/-π+πm(3.8 4 4.2 4.4 4.6 4.8 5

2E

vent

s / 2

0 M

eV/c

0

10

20

30

40

)2) (GeV/cψJ/-π+πm(3.8 4 4.2 4.4 4.6 4.8 5

2E

vent

s / 2

0 M

eV/c

0

10

20

30

40

sidebandsψJ/

3.6 3.8 4 4.2 4.4 4.6 4.8 51

10

210

310

410

ψ(2S)ee→Y(4260)γ

)2) (GeV/cψ)J/-π+πm(2(4 5 6 7 8

2E

ven

ts /

50

MeV

/c

0

5

10

)2) (GeV/cψ)J/-π+πm(2(4 5 6 7 8

2E

ven

ts /

50

MeV

/c

0

5

10

)2) (GeV/cψ)J/-π+πm(2(4 4.5 5

2E

ven

ts /

50

MeV

/c

0

5

10

)2) (GeV/cψ)J/-π+πm(2(4 4.5 5

2E

ven

ts /

50

MeV

/c

0

5

10

ee→Y(4320)γ

X(3872)→J/ψππ



Open Issues in Charmonium Spectroscopy

• All 8 states below threshold have been observed: hc evidence stronger (E835, CLEO), its properties need to be measured accurately.

• The agreement between the various measurements of the ηc mass and width is not satisfactory. New, high-precision measurments are needed. The large value of the total width needs to be understood.

• The study of the η′c has just started. Small splitting from the ψ′ must be understood. Width and decay modes must be measured.

• The angular distributions in the radiative decay of the triplet P states must be measured with higher accuracy.

• The entire region above open charm threshold must be explored in great detail, in particular:– the missing D states must be found– the newly discovered states understood (c⎯c, exotics, multiquark, ...)– Confirm vector states observed in R


Charmonium at PANDA• At 2×1032cm-2s-1 accumulate 8 pb-1/day (assuming 50 % overall

efficiency) ⇒ 104÷107 (c⎯c) states/day.• Total integrated luminosity 1.5 fb-1/year (at 2×1032cm-2s-1, assuming

6 months/year data taking).• Improvements with respect to Fermilab E760/E835:

– Up to ten times higher instantaneous luminosity.– Better beam momentum resolution Δp/p = 10-5 (GSI) vs 2×10-4 (FNAL)– Better detector (higher angular coverage, magnetic field, ability to detect

hadronic decay modes).• Fine scans to measure masses to ≈ 100 KeV, widths to ≈ 10 %.• Explore entire region below and above open charm threshold.• Decay channels

– J/ψ+X , J/ψ → e+e-, J/ψ → μ+μ−

– γγ– hadrons– D⎯D


Hybrids and GlueballsThe QCD spectrum is much richer than that of the quark model as the gluons can also act as hadron components.Glueballs states of pure glueHybrids q⎯qg

Ex o

tic

light

qq

Exotic

cc

1-- 1-+

0 2000 4000MeV/c2

10-2

1

102

•Spin-exotic quantum numbers JPC arepowerful signature of gluonic hadrons.

•In the light meson spectrum exoticstates overlap with conventional states.•In the c⎯c meson spectrum the densityof states is lower and the exotics can be resolved unambiguously.

•π1(1400) and π1(1600) with JPC=1-+.••ππ11(2000) and h(2000) and h22(1950)(1950)•Narrow state at 1500 MeV/c2 seen byCrystal Barrel best candidate for

glueball ground state (JPC=0++).


π1(1400) – Proof of Exotic Wave (CB)Positive

χ (Fit - Data)Negative

χ 2 (Fit - Data)

5σ

5σ

no π1 in Fit

π1 in Fit

2

ρ−

a2

ρ−

a2

ρ−

a2

ρ−

a2

0 1

1

2

2

3

3

GeV /c2 4

GeV /c2 4

0 1

1

2

2

3

3

GeV /c2 4

GeV /c2 4

0 1

1

2

2

3

3

GeV /c2 4

GeV /c2 4

0 1

1

2

2

3

3

GeV /c2 4

GeV /c2 4

CrystalBarrel

m2 (

ηπ0 )

[GeV

2 /c4 ]

m2(ηπ-) [GeV2/c4]


Charmonium Hybrids

• Bag model, flux tube model constituent gluon model and LQCD.

• Three of the lowest lying c⎯c hybrids have exotic JPC (0+-,1-+,2+-)⇒ no mixing with nearby c⎯c states

• Mass 4.2 – 4.5 GeV/c2.• Charmonium hybrids expected to

be much narrower than light hybrids(open charm decays forbidden or suppressed below DD** threshold).

• Cross sections for formation and production of charmonium hybrids similar to normal c⎯c states (~ 100 – 150 pb).

CLEO

Σ

Π

One-gluon exchange

Excited gluon flux


Charmonium Hybrids

•Gluon rich process creates gluonic excitation in a direct way

– ccbar requires the quarks to annihilate (no rearrangement)

– yield comparable tocharmonium production

•2 complementary techniques– Production

(Fixed-Momentum)– Formation

(Broad- and Fine-Scans)

•Momentum range for a survey– p → ~15 GeV

ProductionAll Quantumnumberspossible

RecoilMeson

FormationQuantumnumberslike pp


GlueballsDetailed predictions of mass spectrumfrom quenched LQCD.

– Width of ground state ∼ 100 MeV– Several states predicted below 5

GeV/c2, some exotic (oddballs)– Exotic heavy glueballs:

• m(0+-) = 4140(50)(200) MeV• m(2+-) = 4740(70)(230) MeV• predicted narrow width

Can be either formed directly or produced in ⎯pp annihilation.Some predicted decay modes φφ, φη, J/ψη, J/ψφ ...

Morningstar und Peardon, PRD60 (1999) 034509Morningstar und Peardon, PRD56 (1997) 4043

The detection of nonThe detection of non--exotic glueballs is not trivial, as these states mix withexotic glueballs is not trivial, as these states mix withthe nearby qthe nearby q⎯⎯q states with the same quantum numbers, thus modifying theq states with the same quantum numbers, thus modifying theexpected decay pattern.expected decay pattern.


The f0(1500)

Observed in ⎯pp annihilations by Crystal Barrel (π0ηη, π0π0ηand 3π0 ) and Obelix(π+π-π0, K+K-π0, KK0

Sπ ).

f0(1450) and a0(1370) also observed in same channels.

Mixing between conventionalscalar mesons (0++) and glueball state.

Evidence for tensor glueball at 2 GeV contradictory.

( )( )( ) NNssggf

NNssggf

NNssggf

79.013.060.01370

62.037.069.01500

14.091.039.01710

0

0

0

−−=

−+−=

++=

2/161440 cMeVmG ±=


Hadrons in Nuclear Matter•Partial restoration of chiral symmetry in nuclear matter

– Light quarks are sensitive to quark condensate•Evidence for mass changes of pions and kaons has been deduced previously:

– deeply bound pionic atoms– (anti)kaon yield and phase space distribution

•(c⎯c) states are sensitive to gluon condensate– small (5-10 MeV/c2) in medium modifications for

low-lying (c⎯c) (J/ψ, ηc)– significant mass shifts for excited states:

40, 100, 140 MeV/c2 for χcJ, ψ’, ψ(3770) resp.•D mesons are the QCD analog of the H-atom.

– chiral symmetry to be studied on a single light quark

– theoretical calculations disagree in size and sign of mass shift (50 MeV/c2 attractive – 160 MeV/c2

repulsive)

vacuumvacuum nuclearnuclear mediummedium

π

K

25 MeV

100 MeV

K+

K−

π−

π+

Hayaski, PLB 487 (2000) 96Morath, Lee, Weise, priv. Comm.

D−

50 MeV

D

D+


Charmonium in Nuclei

• Measure J/ψ and D production cross section in ⎯p annihilation on a series of nuclear targets.

• J/ψ nucleus dissociation cross section• Lowering of the D+D- mass would allow

charmonium states to decay into this channel, thus resulting in a dramatic increase of width

ψ(1D) 20 MeV → 40 MeVψ(2S) .28 MeV → 2.7 MeV

⇒Study relative changes of yield and width of the charmonium states.

• In medium mass reconstructed from dilepton (c⎯c) or hadronic decays (D)


Multi-Strangeness SystemsHypernuclei, systems where one (or more) nucleon is substituted by one (or more) hyperon, allow access to a whole set of nuclear statescontaining an extra degree of freedom: strangeness

The lighter single strangeness Λ-hypernuclei have been studied since 50 years allowing to test and define shell model parameters and ΛN interaction. ΛΛ-hypernuclei, Ξ-atoms Ω-atoms are described by more complicated approaches, but allows to have an insight to more complex nuclear systems containing strangeness (hyperon-star, strange-quark star,...)Experimental situation : ~35 Λ-hypernuclei established since 50 years ago. Only 6 ΛΛ-hypernuclei

NAGARA

H. Takahashi et al., PRL 87, 212502-1 (2001)


Ξ- capture: Ξ- p → ΛΛ + 28 MeVΞ-

3 GeV/c

Kaons _

Ξ

ΛΛ

trigger

p_

2. Slowing down and capture

of Ξ− insecondary

target nucleus

2. Slowing down and capture

of Ξ− insecondary

target nucleus

1.Hyperon-

antihyperonproduction

at threshold

1.Hyperon-

antihyperonproduction

at threshold+28MeV

γ

3. γ-spectroscopy

with Ge-detectors

3. γ-spectroscopy

with Ge-detectors

γ

Production of Double HypernucleiProduction of Double Hypernuclei

Ξ-(dss) p(uud) → Λ(uds) Λ(uds)


Proton Electromagnetic Form Factorsin the Timelike Region

The electromagnetic form factors of the proton in the time-like regioncan be extracted from the cross section for the process:

⎯pp → e+e-

First order QED predicts:

Data at high Q2 are crucial to test the QCD predictions for theasymptotic behavior of the form factors and the spacelike-timelikeequality at corresponding values of Q2.

( ) ( ) ( )⎥⎥⎦

⎤

⎢⎢⎣

⎡−++= *22

2*22

222

* cos14

cos12cos

θθπαθ

σE

pM G

sm

Gxs

cd

d h


The dashed line is the PQCD fit:

⎟⎠⎞

⎜⎝⎛

Λ

=

222 ln ss

CG

p

M

μ

E835 Form Factor Measurement

s(GeV2)

102×|GM|(a)

102× |GM|(b)

11.63

12.43

11.018.007.016.074.1 ++

−−12.020.008.017.094.1 ++

−−08.015.005.013.048.1 ++

−−09.017.005.014.063.1 ++

−−



Form Factor Measurement in Panda

In Panda we will be able to measure the proton timelike form factorsover the widest q2 range ever covered by a single experiment, fromthreshold up to q2=30 GeV2, and reach the highest q2.• At low q2 (near threshold) we will be able to measure the form factors with

high statistics, measure the angular distribution (and thus |GM| and |GE| separately) and confirm the sharp rise of the FF.

• At the other end of our energy region we will be able to measure the FF at the highest values of q2 ever reached, ≤ 25-30 GeV2, which is 2.5 larger than the maximum value measured by E835. Since the cross sections decrease ~1/s5, to get comparable precision to E835 we will need ~82 times more data.

• In the E835 region we need to gain a factor of at least 10-20 in data size to be able to measure the electric and magnetic FF separately.


Crossed-Channel Compton Scattering

H, E(x, ξ, t)

H, E(x, ξ, t)~ ~

γ* γ

non-perturbative QCD

perturbative QCDWide angle Compton scatteringfactorisation into hard amplitude(calculable in perturbative QCD)

and soft amplitude(information on parton distributions)

Reversed Deeply Virtual Compton Scattering

pp → γγclear experimental signatureboth baryons in ground state

σ ≈ 2.5pb @ s ≈10 GeV2

L = 2·1032 cm-2 s-1→ 103 events per month

Identical diagramreversed


The Detector

• Detector Requirements:– (Nearly) 4π solid angle coverage (partial wave analysis)– High-rate capability (2×107 annihilations/s)– Good PID (γ, e, µ, π, K, p)– Momentum resolution (≈ 1 %)– Vertex reconstruction for D, K0

s, Λ– Efficient trigger– Modular design

• For Charmonium:– Pointlike interaction region– Lepton identification– Excellent calorimetry

• Energy resolution• Sensitivity to low-energy photons


Panda Detector


Target SpectrometerTarget Spectrometer

p of momentum from 1.5 up to 15 GeV/c2 Tesla solenoidproton pellet target or gas jet targetMicro Vertex DetectorInner Time of Flight detector Tracking detector: Straw Tubes/TPCDIRCElectromagnetic CalorimeterMuon countersMultiwire Drift Chambers


Forward SpectrometerForward Spectrometer

Multiwire Drift Chambers/ Straw tubesdeflecting dipole: 2 Tesla·meterForward DIRC and RICHForward Electromagnetic CalorimetersTime of Flight countersHadron Calorimeter


Collaboration

• At present a group of 350 physicistsfrom 47 institutions of 15 countries

Basel, Beijing, Bochum, Bonn, IFIN Bucharest, Catania, Cracow, Dresden, Edinburg, Erlangen, Ferrara, Frankfurt, Genova, Giessen, Glasgow, GSI, Inst. of Physics Helsinki, FZ Jülich, JINR Dubna, Katowice, Lanzhou, LNF, Mainz, Milano, Minsk, TU München, Münster, Northwestern,

BINP Novosibirsk, Pavia, Piemonte Orientale, IPN Orsay, IHEP Protvino, PNPI St. Petersburg, Stockholm,

Dep. A. Avogadro Torino, Dep. Fis. Sperimentale Torino, Torino Politecnico, Trieste, TSL Uppsala, Tübingen,

Uppsala, Valencia, SINS Warsaw, TU Warsaw, AAS Wien

Basel, Beijing, Bochum, Bonn, IFIN Bucharest, Catania, Cracow, Dresden, Edinburg, Erlangen, Ferrara, Frankfurt, Genova, Giessen, Glasgow, GSI, Inst. of Physics Helsinki, FZ Jülich, JINR Dubna, Katowice, Lanzhou, LNF, Mainz, Milano, Minsk, TU München, Münster, Northwestern,

BINP Novosibirsk, Pavia, Piemonte Orientale, IPN Orsay, IHEP Protvino, PNPI St. Petersburg, Stockholm,

Dep. A. Avogadro Torino, Dep. Fis. Sperimentale Torino, Torino Politecnico, Trieste, TSL Uppsala, Tübingen,

Uppsala, Valencia, SINS Warsaw, TU Warsaw, AAS Wien

http://www.gsi.de/panda

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

PAX


Polarized Antiproton eXperiments

Cerenkovpppp →↑↑

Fixed target experiment (√s<2 GeV):pol./unpol. pbar beam (p<4 GeV/c)internal H polarized target

Proton EFFs

−+↑↑ → eepp

pbar-p elastic

Nucleon structure: polarized reactions

Asymmetric collider (√s=15 GeV): polarized antiprotons in HESR (p=15 GeV/c)polarized protons in CSR (p=3.5 GeV/c)

Parton distribution: transversity

Xeepp −+↑↑ →

Drell-Yan

Charmonium

XJpp ψ/→↑↑

SSA

XllDXpp −+↑ → ,


Nucleon Structure and Transverse Spin Effects

transversely polarisedquarks and nucleons

h1(x): helicity flip chiral-odd needs a chiral odd partner

=q1h −=q

1f =q1g −

unpolarised quarksand nucleons

longitudinally polarisedquarks and nucleons

HERMES,COMPASS,JLab PAX,RHIC,Jparc

Inclusive DIS Semi-inclusive DIS Drell-Yan

h1xh1h1xH1

т


Drell-Yan

,...d,d,u,uq =

M invariant Massof lepton pair /2 / 2

2121 sQxsMxxxxx LFF =≡=−= τ

[ ])( )()( )(1 94

21212

212

2

2

2

xqxqxqxqexxsMdxdM

dq

qF

++

= ∑πασsM 2

−+→→ llqq *γ

Μ2 > 4 GeV2


h1 from ⎯pp Drell-Yan

Similar predictions by Efremov et al., Eur. Phys. J. C35, 207 (2004)

PAX : Μ2/s=x1x2~0.02-0.3valence quarks

(ATT large ~ 0.2-0.3 )

)()()()(ˆ

21

2111

xuxuxhxhaA uu

TTTT ≈

Anselmino et al.PLB 594,97 (2004)

[ ][ ]∑

∑+

+=

+−

=↑↓↑↑

↑↓↑↑

q q

q qqqqqTTTT xqxqxqxqe

xhxhxhxheaA

)()()()(

)()()()(ˆ

dddd

21212

211121112

σσσσ

• u-dominance• |h1u|>|h1d|

1year run: 10 % precision on the h1u(x) in the valence region

Pp=10%Pp=30%


h1 from pp Drell-Yan

Barone, Calarco, Drago

Martin, Schäfer, Stratmann, Vogelsang

h1q (x ,Q2)

h1q (x, Q2) small and with much

slower evolution thanΔq(x, Q2) and q(x, Q2) at small x

- h1q (x, Q2)≠

RHIC: M2/s=x1x2~10-3 → sea quarks (ATT ~ 0.01 )

JPARC/U70: M2/s=x1x2~10-1-10-2 → valence and sea (ATT ~ 0.1 )

PAX: M2/s=x1x2~10-1-10-2 → valence and sea (ATT ~ 0.1 )

[ ][ ] )()(

)()(ˆ)()()()(

)()()()(ˆ

21

2111

21212

211121112

xuxuxhxha

xqxqxqxqe

xhxhxhxheaA uu

TTq q

q qqqqqTTTT ≈

+

+=

∑∑


DY Event Distribution

pp--pp

At x1=x2 ATT ~ h1u2

Direct measurement of h1ufor 0.05<x<0.5

M2/s = x1x2 ~ 0.02-0.3

pp--pp, , pp--dd

Extraction of h1d, h1q

for x<0.2

p↑p↑, p↑p↑, p↑d↑: complete mapping of transversity


Single Spin Asymmetries

pq

Pqπk Collins effect = fragmentation of polarized quark

depends on Pq· (pq x k)

Chiral-Odd

Sivers effect = number of partons in polarizedproton depends on P · (p x k)

Chiral-Even

P

pp

k

q

k

qPq

pp

Boer-Mulders effect = polarization of partons in unpolarized proton depends on Pq · (p x k)

Chiral-Odd

These effects may generate SSA ↓↑

↓↑

+−

=σσσσ

d dd d

NA

pq

PΛ Λk Polarizing FF = polarization of hadrons from

unpolarized partons depends on PΛ · (pq x k)

PDFs

FFs


BNL-AGS √s = 6.6 GeV0.6 < pT < 1.2 p↑p

E704 √s = 20 GeV0.7 < pT < 2.0 p↑p

STAR-RHIC √s = 200 GeV1.1 < pT < 2.5 p↑p

E704 √s = 20 GeV0.7 < pT < 2.0 p↑p

SSA, pp → πX


The Sivers Function

M. Anselmino et al.,

Phys. Rev. D72, 094007 (2005)

DYTTSIDISTT xfxf )p,()p,( 21

21

⊥⊥ −=

Test of Universality

A.V. Efremov et al.,

Phys. Lett. B 612, 233 (2005)

XeeppPAX −+→↑:

y22/1 / ±= esMx

XppE π→↑:704

XeepSIDIS π→↑:


The Sivers Function

No Collins effect U.D’Alesio and F. Murgia

hep-ph/0612208

DXpp →↑ DXpp →↑

Xpp γ→↑ccqq →

No fragmentation process


Proton Electromagnetic Form Factors

(Phys. Rev.C 68 (2003) 034325)

JLab PT data

SLAC RS data

TWO DIFFERENTS METHODS

TWO DIFFERENTS RESULTS

COMPARISON BETWEEN

ROSENBLUTH SEPARATION AND

POLARIZATION TRANSFER TECHNIQUES


Proton Timelike Form Factors

• Double-spin asymmetry in pp → e+e-

– independent GE-Gm separation– test of Rosenbluth separation in

the time-like region

-0.4

-0.2

0

0.2

0.4

5 10 15 20 25 30 35 40

1/Q fit

(log2 Q2) /Q2 fit

impr. (log2 Q2) /Q2 fitIJL fit

Pol

ariz

atio

n P

y (fo

r θ

= 4

5°)

q2 (GeV2)

( )[ ]2

p2

2E

22M

2M

*E

y

m4/q

/|G|)(sin|G|)(cos1)GGIm()2sin(A

=τ

ττθ+θ+⋅⋅θ

=

S. Brodsky et al., Phys. Rev. D69 (2004)

• Single-spin asymmetry in pp → e+e-

Measurement of relative phasesof magnetic and electric FF inthe time-like region


pp,pd,pp beams are possiblepp,pd,pp beams are possible• APR: Antiproton Polarizer Ring (Ppbar>0.2)

• CSR: Cooled Synchrotron Ring ( p<3.5 GeV/c)

• HESR: High Energy Synchrotron Ring (p<15 GeV/c)

Asymmetric collider Luminosity up to 5·1031 cm-2s-1


PAX Detector Concept

Designed for Collider but compatible with fixed target

(200 μm)

(20 μm)

GEANT simulation


Polarized Antiproton Experiments

Phase I: Proton time-like FFsHard pbar-p elastic scatt.

Fixed target experiment (√s<2 GeV):pol./unpol. pbar beam (p<4 GeV/c)internal H polarized target

Phase II: Transversity Distribution

Asymmetric collider (√s=15 GeV): polarized antiprotons in HESR (p=15 GeV/c)polarized protons in CSR (p=3.5 GeV/c)


Antiproton PolarizationThe polarization of antiprotons is based on the Spin Filtering method (interaction of unpolarized antiprotons with a polarized hydrogen target). This technique has been experimentally tested in 1992 (Filtex experiment) and it works, but:

1. Controversial interpretations of FILTEX experiment• Further experimental tests necessary• How does spin-filtering works?• Which role do electrons play?→ Tests with protons at COSY

2. No data to predict polarization from filtering with antiprotons.→ Measurements with antiprotons at AD/CERN

Fall 2007 Technical proposal to COSY-PAC for spin filteringTechnical proposal to SPSC for spin filtering at AD

2007-2008 Depolarization studies2008-2009 Design and construction phase2009-2010 Spin-filtering studies at COSY

Commissioning of AD experiment2010 Installation at AD2010-2011 Spin-filtering studies at AD


Summary and Outlook:Spectroscopy at FAIR

PANDAHigh-intensity cooled antiproton beamsHigh precision spectroscopy from √s 2.25 GeV to 5.5 GeV:• charmonium• hybrids and glueballs• multiquark• mesons and hadrons• open charm


Summary and Outlook:Nucleon Structure at FAIR

PANDA• Proton Timelike Form Factors

– Very high-statistics measurement near threshold– Measure angular distribution ⇒ |GE|/|GM|– Extend q2 range to 20-25 GeV2

PAX• Transversity in polarized ⎯pp DY• Single Spin Asymmetries and Sivers Function• Proton Timelike Form Factors

– Measurement with polarized beams– Single- and double-spin observables– Moduli and phases of TL form factors


Recent decision by German Minister Ms. Schavan:

Start of the International FAIR Project

on November 7, 2007

together with all partners that have expressed their commitment on FAIR.

Backup Slides


FAIR Schedule


Transversity and Tensor Charges

Soffer inequality M. Anselmino et al.

hep-ph/0008186

Transversity

δu≈ 0.39, δd≈-0.16

Tensor charges

M. Wakamatsu

arXiv: 0705.2917


Elastic Scattering

SpinSpin--dependence at dependence at largelarge--PP⊥⊥ (9090°°cmcm):):Hard scattering takes place Hard scattering takes place only with spins only with spins ↑↑↑↑..

D.G. Crabb et al., PRL 41, 1257 (1978)

T=10.85 GeV

Similar studies in pp elastic scattering

HighHigh--t pp from ZGS, AGSt pp from ZGS, AGS

LowLow--E pp, pd at ADE pp, pd at AD

Polarization build-up studies

70

Principle of spin filter methodPrinciple of spin filter methodP beam polarizationQ target polarizationk || beam direction

σtot = σ0 + σ⊥·P·Q + σ||·(P·k)(Q·k)

transverse case:

Q0tot ⋅σ±σ=σ ⊥±

longitudinal case:

Q)( ||0tot ⋅σ+σ±σ=σ ⊥±

For initially equally populated spin states: ↑ (m=+½) and ↓ (m=-½)

Unpolarizedanti-p beam

Polarized H target

Documents

Experimental Study of the Strong Interaction at FAIR · Experimental Study of Charmonium e+e-annihilation • Direct formation only possible for JPC = 1--states. • All other states