The completion of single-spin asymmetry measurements at the PROZA setup

The completion The completion of single-spin asymmetry of single-spin asymmetry

measurements measurements at the PROZA setup at the PROZA setup

V. MochalovV. Mochalov (IHEP, Protvino) (IHEP, Protvino)On behalf of the On behalf of the PROZA-SPASCHARMPROZA-SPASCHARM

collaborationcollaboration

5 September 20095 September 2009 V. Mochalov, PROZA-M experimentV. Mochalov, PROZA-M experiment 22

Introduction remarkIntroduction remark

This talk itself is This talk itself is sadsad in some sense: in some sense:This is probably the This is probably the last reportlast report devoted to the devoted to the

current PROZA activitycurrent PROZA activityPolarization program with old JINR target is Polarization program with old JINR target is

completedcompleted after 30 years of investigations after 30 years of investigationsNevertheless Nevertheless new spin programnew spin program at IHEP is at IHEP is

under preparation (see next talk by under preparation (see next talk by S.NurushevS.Nurushev) )


OutlineOutline Recent Single-spin asymmetry results from Recent Single-spin asymmetry results from

PROZAPROZA AANN in the beam (non-polarized) fragmentation region in the beam (non-polarized) fragmentation region AANN in the target (polarized) fragmentation region in the target (polarized) fragmentation region

Review of previous results from PROZAReview of previous results from PROZA Polarization and single-spin asymmetry in exclusive Polarization and single-spin asymmetry in exclusive

(charge-exchange) reactions(charge-exchange) reactions Single-spin asymmetry in inclusive reactions in the Single-spin asymmetry in inclusive reactions in the

central region central region PROZA – answers and questions (instead of PROZA – answers and questions (instead of

conclusion)conclusion)


Asymmetry in the beam Asymmetry in the beam fragmentation regionfragmentation region

Negative beam (Negative beam (ππ--/K/p-bar:97.9/1.8/0.3%)/K/p-bar:97.9/1.8/0.3%) Beam particle identificationBeam particle identification Propane-diol (CPropane-diol (C33HH88OO22) target with 90% average ) target with 90% average

polarization (diameter 20 mm, length 200 mm )polarization (diameter 20 mm, length 200 mm ) Neutral particle triggerNeutral particle trigger EMC (800 lead glass channels) with trigger on EMC (800 lead glass channels) with trigger on

transverse momenta ptransverse momenta pTT


Negative particle beam Negative particle beam profile on the targetprofile on the target

x(target) x(target) = = y(target)y(target)=3.5 mm (98% inside the target)=3.5 mm (98% inside the target)


AANN in the in the π-d↑→π0X reaction

AANN in the in the K-d↑→π0X reaction is equaled zero (-0.46.1)% at 0.6<pT (GeV/c)(GeV/c) <1.2 and

AN=(116.1)% at pT>1.2 (GeV/c)(GeV/c)


ppTT dependence of A dependence of ANN in the beam in the beam

fragmentation regionfragmentation region

Asymmetry is zero at small pAsymmetry is zero at small pTT ( (red pointsred points – previous – previous

results, published in 1989 ) andresults, published in 1989 ) and Is significant at large pIs significant at large pTT: A: ANN=(13.6=(13.62.6(stat)2.6(stat)2.0(syst))% 2.0(syst))%

at pat pTT>1 (GeV/c)>1 (GeV/c) and 0.7 (0.7<xand 0.7 (0.7<xFF<1.0)<1.0)


First asymmetry measurements First asymmetry measurements at the at the polarized polarized target fragmentationtarget fragmentation region region

Asymmetry in the Asymmetry in the inclusive inclusive ππ00-production -production in the polarized target in the polarized target fragmentation region fragmentation region was measured in 1996-was measured in 1996-2002 in the reactions 2002 in the reactions

π-p↑→π0X

pp↑→π0X

AANN increases with |x increases with |xFF| |

increased. The result is increased. The result is in agreement with E704 in agreement with E704 and STAR data. and STAR data. pp↑→π0X, Phys.At.Nucl, 68 (2005)1790

π-p↑→π0X, Phys.At.Nucl, 67 (2004) 1495


Final PROZA-2 Final PROZA-2 measurementsmeasurements

Asymmetry in Asymmetry in pp↑→π0X in the polarized target in the polarized target fragmentation region at 50 GeV. fragmentation region at 50 GeV.

Two sets of data (2005 and 2007) are being used for Two sets of data (2005 and 2007) are being used for analysis. analysis.

EMC consists of 720 lead glass blocksEMC consists of 720 lead glass blocks proton beam up to 7∙10proton beam up to 7∙1066 p/cycle p/cycle


Beam properties and stabilityBeam properties and stability

Proton beam was Proton beam was extracted from U70 extracted from U70 vacuum chamber vacuum chamber using bent crystal (80 using bent crystal (80 mrad)mrad)

xx=2.7 mm, =2.7 mm, yy=3.7 =3.7

mmmm P/P<0.013%P/P<0.013% Beam position Beam position

stability stability <x><x><0.1 mm<0.1 mm


γγ and and ππ00 reconstruction in reconstruction in EMCEMC

EMC-720 was adjusted to EMC-720 was adjusted to measure low energy measure low energy gammas (2.2 MeV/ADC gammas (2.2 MeV/ADC channel)channel) Nevertheless reconstructed Nevertheless reconstructed

energy depends on real energy depends on real γγ energyenergy

EMC is 2.3 m EMC is 2.3 m downstream target:downstream target: Reconstructed energy Reconstructed energy

depends on angle of depends on angle of incident incident γγ

Special algorithm was Special algorithm was developeddeveloped


ππ00 mass mass

((ππ00)=17 MeV (left))=17 MeV (left) <m<m((ππ00)> after correction (circles) does not depend on )> after correction (circles) does not depend on

angle and energy (right)angle and energy (right)


ππ00 kinematics kinematics


AANN in the reaction in the reaction pp↑→π0X (close to (close to

final) at 50 GeV (final) at 50 GeV (2005+20072005+2007 data) data)

xxFF AANN,%,%

-(0.13-0.11)-(0.13-0.11) -(0.8-(0.82.2) 2.2)

-(0.17-0.13)-(0.17-0.13) -(2.0-(2.01.8) 1.8)

-(0.21-0.17)-(0.21-0.17) -(1.5-(1.51.9) 1.9)

-(0.25-0.21)-(0.25-0.21) -(2.-(2.332.2.11) )

-(0.35-0.25)-(0.35-0.25) -(-(55..8811..88) )

-(0.45-0.35)-(0.45-0.35) -(-(66..8844..11) )

-(0.60-0.45)-(0.60-0.45) -(-(1111..0055..88) )

At -0.6<xF<-0.25 single spin asymmetry AN= -(-(66..2211..55)) %

Preliminary


Comparison of the asymmetry Comparison of the asymmetry with other experimentswith other experiments

AANN in the inclusive in the inclusive ππ0 0

production at polarized particle production at polarized particle fragmentation region at fragmentation region at 0.25<x0.25<xFF<0.6 at 50 GeV <0.6 at 50 GeV ((66..2211..55))%% is in a very good is in a very good agreement with other agreement with other experiments:experiments:

AANN In the reaction In the reaction ππ--pp↑↑→→ππ00XX at at 40 GeV 40 GeV ((66..9922..88) )

With E704 data at 200 GeV With E704 data at 200 GeV ((66..3300..77) )

AANN in inclusive in inclusive ππ00 production production does NOT depend on does NOT depend on

beam energy.beam energy.


Polarization in the reaction Polarization in the reaction π-p↑→π0n

Polarization P(t) in the range of 0<|t|<0.35 (GeV/c)2 equals 5.00.7%.

There is a minimum at "crossover" effect region t=-0.25 (GeV/c)2

Polarization changes its sign in the dip region in the differential cross-section.

There are oscillations in polarization behavior.

V.D. Apokin et al., Sov. J. Nucl. Phys. 45:840, 1987, [Yad.Fiz.45:1355-1357,1987]

V.D. Apokin et al. Z.Phys.C15:293,1982


Polarization in the reactions Polarization in the reactions

π-p↑→n and and π-p↑→’(958)n An essential polarization in wide An essential polarization in wide

interval of 0.05<-t<1.6 (GeV/c)interval of 0.05<-t<1.6 (GeV/c)22 in in π-p↑→n at 40 GeV.at 40 GeV.

In the region 0.05<-t<0.4 (GeV/c)In the region 0.05<-t<0.4 (GeV/c)22 polarization is small (-5% );polarization is small (-5% );

with -t increasing up to ~1(GeV/c)with -t increasing up to ~1(GeV/c)22, , the polarization absolute value the polarization absolute value increases. Aincreases. ANN=(-44=(-4411)% at the |t| 11)% at the |t| range of 0.8-1.6 (GeV/c)range of 0.8-1.6 (GeV/c)22

polarization changes a sign near polarization changes a sign near -t=1.8 (GeV2/c)-t=1.8 (GeV2/c)22 . .

The averaged value of the The averaged value of the polarization in the reaction polarization in the reaction π-

p↑→’(958)n in the region of 0.05< in the region of 0.05< -t <0.5 (GeV2/c)-t <0.5 (GeV2/c)22 is (-17 is (-17 8)%. 8)%.

V.D. Apokin et al., Z.Phys.C35:173,1987.


Asymmetry in the reactions Asymmetry in the reactions

π-p↑→(783)n and and π-p↑→f2(1270)n was registered via was registered via

γγ decay (branching decay (branching only 8.9%).only 8.9%).

Asymmetry is large in Asymmetry is large in both reactionsboth reactions

Indication on minimum Indication on minimum at –t=0.2 (GeV/c)at –t=0.2 (GeV/c)22 for for both reactionsboth reactions

I.A. Avvakumov et al. Yad.Fiz.42:1146,1985

V.D. Apokin et al. Yad.Fiz.47:727-730,1988]


Asymmetry in inclusive Asymmetry in inclusive ππ00 production at production at xxFF=0=0

Asymmetry in the Asymmetry in the reaction reaction π-p(d)↑→π0X is big and does not depend on target flavor. The result can not be explained by Sivers and Collins functions. Asymmetry in π-p(d)↑→ηX is even bigger

Asymmetry in the Asymmetry in the reaction reaction pp↑→π0X is zero at the whole pT interval. The result confirms E-704 measurements at 200 GeV.

pp↑→ π0X, Phys.At.Nucl, 67 (2004) 1487

π-p↑→π0X, Phys.Lett.B243,461 (1990)


PROZA – PROZA – answersanswers and and quesquestionstions exclusiveexclusive

Essential polarization (asymmetry) Essential polarization (asymmetry) was found in all reactionswas found in all reactions

There is indication on asymmetry There is indication on asymmetry oscillationsoscillations

There is a minimum at "crossover" There is a minimum at "crossover" effect region ineffect region in π-p↑→π0n Polarization changes sign in the Polarization changes sign in the dip region in the disserential cros-dip region in the disserential cros-sectionsection

Simple Regge model can not Simple Regge model can not describe polarization modification describe polarization modification required:required: U matrix with pomeron spin-flipU matrix with pomeron spin-flip Odderon pole is required in Odderon pole is required in

addition to addition to ρρ-pole-pole Prediction: Prediction: PP((π0)+2P(η)=P(η) aa00(980) – see Achasov.(980) – see Achasov.

Does the asymmetry magnitude Does the asymmetry magnitude increase with meson mass?increase with meson mass?

Is it real effect for all particles? Is it real effect for all particles? Better accuracy is required.Better accuracy is required.

Is it valid for other reactions?Is it valid for other reactions? What is theoretical explanation of What is theoretical explanation of

this effect?this effect? How we can discriminate between How we can discriminate between

models?models? There is no predictions for the There is no predictions for the

most of the reactions except most of the reactions except π-

p↑→π0n and: and: It is very interesting to measure It is very interesting to measure

these processes with good these processes with good accuracy.accuracy.


PROZA – PROZA – answersanswers and and quesquestionstions inclusiveinclusive

Asymmetry mainly does not depend on Asymmetry mainly does not depend on energy (see also E704, BNL, RHIC)energy (see also E704, BNL, RHIC)

Essential asymmetry was found for u- Essential asymmetry was found for u- and d- quark particles. and d- quark particles.

Asymmetry is quark flavor dependend Asymmetry is quark flavor dependend (pion and proton beams). Asymmetry (pion and proton beams). Asymmetry in η production is bigger than in πin η production is bigger than in π00 production (see also STAR)production (see also STAR)

Asymmetry increases with p_T at the Asymmetry increases with p_T at the central region in the reaction central region in the reaction π-

p↑→π0X Threshold effect and scaling was Threshold effect and scaling was

observed.observed. Asymmetry in non-polarized beam and Asymmetry in non-polarized beam and

polarized target (beam) regions close polarized target (beam) regions close to the edge of phase space is equal in to the edge of phase space is equal in the reaction the reaction π-p↑→π0X

We have very good possibility to We have very good possibility to measure asymmetry in different measure asymmetry in different channels at intermediate energies with channels at intermediate energies with good accuracy.good accuracy.

PQCD type models do not work at PQCD type models do not work at these energies?these energies?

What is the asymmetry for ss-bar and What is the asymmetry for ss-bar and heavier states (heavier states (φφ and others) and others)??

Most of the models can not predict Most of the models can not predict non-zero asymmetry in the central non-zero asymmetry in the central region and describe p_T behavior.region and describe p_T behavior.

It is very important to measure It is very important to measure asymmetry in wide kinematic region in asymmetry in wide kinematic region in different channels to discriminate different channels to discriminate between different models.between different models.


We have found a lot of interesting in spin We have found a lot of interesting in spin physicsphysics

We all have desires, possibilities and duties We all have desires, possibilities and duties trying to find much more inviting and trying to find much more inviting and

unpredictableunpredictable


Backup slidesBackup slides


IHEP/1968 -1977IHEP/1968 -1977HERA Collaboration (France-USSRHERA Collaboration (France-USSR))

Polarization in elastic scattering of particles and Polarization in elastic scattering of particles and antiparticles on polarized protons at 40 and 45 GeVantiparticles on polarized protons at 40 and 45 GeV..

Pomeron may carry the spin flip interaction (the first Pomeron may carry the spin flip interaction (the first experimental hint)experimental hint)

Polarization in the elastic scattering of particle and Polarization in the elastic scattering of particle and antiparticle is not equal each to other with opposite sign antiparticle is not equal each to other with opposite sign in general, as it was predicted in the asymptotic model in general, as it was predicted in the asymptotic model [S.M. Bilenky et al. 1963][S.M. Bilenky et al. 1963]

The energy variation of polarization depends on the type The energy variation of polarization depends on the type of particles and the magnitude of t.of particles and the magnitude of t.

Spin rotation parameter is consistent with the Chou - Spin rotation parameter is consistent with the Chou - Yang model of rotating hadronic matter.Yang model of rotating hadronic matter.

Chirality conservation hypothesis does not workChirality conservation hypothesis does not work

The completion of single-spin asymmetry measurements at the PROZA setup

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