Double Spin Azimuthal Asymmetries by dffhrtcv3

VIEWS: 3 PAGES: 30

									New target transverse spin dependent
azimuthal asymmetries from
COMPASS experiment
                  Bakur Parsamyan
                INFN & University of Turin

         on behalf of the COMPASS collaboration



               SPIN - Praha - 2007
               Prague, July 08 – 14, 2007



                                                  1
Outline

    General expression of polarized SIDIS cross-section
    Target transverse spin asymmetries
    COMPASS experimental setup
    Event selection
    Extraction
          1D method
                Systematic checks
          2D method
                Correlation Coefficients
    Results
    ALT h s ) asymmetry, comparison with the model
      cos(


    Conclusions




     SPIN – Praha – 2007, July 08-14                Bakur Parsamyan   2
General expression of polarized SIDIS cross-section
A.Kotzinian, Nucl. Phys. B441, 234 (1995).
                                                                                                                  This is a general,
Bacchetta, Diehl, Goeke, Metz, Mulders and Schlegel JHEP 0702:093,2007
                                                                      model independent expression
       d
                                                                    which is also valid for exclusive
dxdyd dzdh dPh2
                                                                                                       reactions and for entire phase space of
    2
         y     2
                         2

                1  2 x  { FUU ,T   FUU , L                         2 (1   ) cos h FUU h
                                                                                              cos
                                                                                                                 SIDIS (TFR, CFR)
xyQ 2 2(1   )         

 cos( 2h ) FUU 2h )  PLl 2 (1   ) sin h FLU h
                cos(                               sin                                                        Azimuthal modulations:
                                                                                                             2 polarization independent
 PL [ 2 (1   ) sin h FUL h   sin( 2h ) FUL 2h ) ]
                            sin                   sin(                                                  1 single beam polarization dependent
                                                                                                       2 single target longitudinal polarization
 PLN PLl [ 1   2 FLL        2 (1   ) cos h FLcos h ]
                                                      L                                                               dependent
                                                                                                        1 double beam + target longitudinal
 P [sin(h  S )  F
     T
      N                      sin( h S )
                            UT ,T             F    sin( h S )
                                                    UT , L                                                    polarization dependent
                                                                                                        5 single target transverse polarization
 sin(h  S ) FUT h S )   sin(3h  S ) FUT 3h S )
                   sin(                            sin(
                                                                                                                      dependent
                                                                                                         3 double beam + target transverse
 2 (1   ) sin S FUT S 
                       sin
                                         2 (1   ) sin( 2h  S ) FUT 2h S ) ]
                                                                       sin(

                                                                                                               polarization dependent
 P N PLl [ 1   2 cos(h  S ) FLT h S ) 
   T
                                    cos(
                                                                         2 (1   ) cos S FLT S
                                                                                              cos


                                                                                                             1  y  1 y 2 2
 2 (1   ) cos( 2h  S ) F          cos( 2h S )
                                                          ]},                                where                 4
                                                                                                                                 ,   2 xM / Q
                                        LT                                                                1  y  2 y  1 y 2 2
                                                                                                                  1 2
                                                                                                                          4

          SPIN – Praha – 2007, July 08-14                                                            Bakur Parsamyan                          3
General expression of polarized SIDIS cross-section

 d  d 00  PLl d L 0  PLN (d 0 L  PLl d LL )  P N (d 0T  PLl d LT )
                                                        T
          N                                     N
where, PL - target longitudinal polarization, P - target transverse polarization,
                                               T
  l
PL - beam longitudinal polarization.
                    Target transverse spin dependent azimuthal
                                          modulations
 d 0T  A sin(h  s )  A2 sin(3h  s )  A3 sin(h  s )
          1


               A4 sin(2h   s )  A5 sin  s             Published by HERMES & COMPASS



d LT  A6 cos(h   s )  A7 cos(2h   s )  A8 cos  s



For Collins and Sivers asymmetries from COMPASS see next talk by Girisan Venugopal


    SPIN – Praha – 2007, July 08-14                               Bakur Parsamyan           4
Transverse spin dependent azimuthal modulations

w1 (h ,  s )  sin(h   s )
w2 (h ,  s )  sin(h   s )                             8 – modulations.
w3 (h ,  s )  sin(3h   s )            UT
w4 (h ,  s )  sin( s )
w5 (h ,  s )  sin(2h   s )
w6 (h ,  s )  cos(h   s )
                                                  5 – single spin             3 – double spin
w7 (h ,  s )  cos( s )                  LT
w8 (h ,  s )  cos(2h   s )
                                            5
d (h ,  s )  (1  ST  D wi (h ,s ) ( y ) AUT(h ,s ) wi (h ,  s ) 
                                                 wi

                                           i 1
                                       8
                      P ST  D wi (h ,s ) ( y) ALT(h ,s ) wi (h ,  s )  ...).
                       beam
                                                  wi

                                     i 6
                                                                          FUw(i LhT,s )
                                                                                (
ST - target polarization, Pbeam – beam polarization    w h ,
                                                      AU i((L ),Ts )            ),

D wi (h ,s ) ( y ) – Depolarization factor                                FUU ,T
     SPIN – Praha – 2007, July 08-14                            Bakur Parsamyan             5
Interpretation of the transverse asymmetries
Within QCD parton model                Ai  DF  FF (i  1,..8)




                                  →
                                            Twist-2:
 AUT h s )  h1q  H1h
  sin(
                        q
                                                                     ALT h s )  g1T  D1hq
                                                                      cos(           q

 AUT h s )  f1T q  D1hq
  sin(            



 AUT h s )  h1q  H1h
  sin(3
                  T      q
                                                                           double spin

  single spin                  Twist-2 + kT/Q kinematical corrections:



AUT (s ) 
 sin

             Q
                h1  H1qh  f1Tq  D1hq 
             M q
                                                                   ALTs(s ) 
                                                                    co            M q
                                                                                  Q
                                                                                    g1T  D1hq

AUT h s )   h1q  H1h  f1T q  D1hq 
               M                                                    cos(2h s )   M q
 sin(2
                     T       q
                                    
                                                                   ALT             g1T  D1hq
               Q                                                                    Q

     SPIN – Praha – 2007, July 08-14                              Bakur Parsamyan                6
Definition of the UT asymmetries
                              AUT ,hw s )
                               sin( 

AUT h s ) 
 sin(                              ra

                     Dsin(h s ) ( y ) f ST                                                               2(1  y )
                                                          Dsin(h S ) ( y )  D sin(3h S ) ( y ) 
                              sin(3h
                             AUT ,raw s )                                                               1  (1  y ) 2
AUT h s ) 
 sin(3

                     Dsin(3h s ) ( y) f ST
                               sin(2h
                              AUT ,raw s )
AUT h s ) 
 sin(2

                     Dsin( 2h s ) ( y ) f ST                                                   2(2  y) 1  y
                                                     Dsin(2h S ) ( y)  Dsin(S ) ( y) 
                     AUT ,sw
                      sin( )
                                                                                                    1  (1  y)2
AUin(s ) 
 s                         ra

              Dsin(s ) ( y ) f ST
   T



  sin(h s )               AUT ,hw s )
                              sin( 
                                                         sin(h  S )          1  (1  y ) 2
A                                ra
                         sin(h s )
                                                     D                   ( y)                 1
  UT
                     D                  ( y ) f ST                              1  (1  y ) 2



“raw” – indicates number event asymmetry extracted as an amplitude of the corresponding modulation

 f - target dilution factor, ST - target polarization

D wi (h ,s ) – Depolarization factor
       SPIN – Praha – 2007, July 08-14                                                Bakur Parsamyan                      7
Definition of the LT asymmetries


 cos(2h s )
                               cos(2
                              ALT ,rawh s )
A                
 LT
                     Dcos( 2h s ) ( y) fPbeam ST             cos(2h S )              cos(S )           2 y 1 y
                                                            D                   ( y)  D              ( y) 
                       ALT ,rsw)
                          cos(
                                                                                                             1  (1  y)2
ALT (s ) 
 cos                           a

              Dcos(s ) ( y) fPbeam ST
                             cos(h
                            ALT ,raws )                                                 y (2  y )
ALTs(h s ) 
 co
                                                           D cos(h S ) ( y ) 
                  Dcos(h s ) ( y) fPbeam ST                                          1  (1  y ) 2

f - target dilution factor, ST - target polarization

D wi (h ,s ) – Depolarization factor


 AUT(,h ,s )  Dwi (h ,s ) ( y) f ST AUT(h ,s ) , (i  1,..,5)
  wi
      raw
                                          wi
                                                                             - Single Spin Asymmetries


 ALT(,h ,s )  Dwi (h ,s ) ( y) fP eam ST ALT(h ,s ) , (i  6,.., 8)
  wi
      raw                             b
                                               wi
                                                                                  - Double Spin Asymmetries


      SPIN – Praha – 2007, July 08-14                                           Bakur Parsamyan                        8
The COMPASS Experimental Setup
       COmmon Muon Proton Apparatus for Structure and Spectroscopy
   Longitudinally polarized µ+ beam (160 Gev/c).
   Longitudinally or Transversely polarized 6LiD target
   Momentum, tracking and calorimetric measurements, PID


                  High energy beam
                  Large angular acceptance
                  Broad kinematical range




                                                            CERN SPS North Area.
                                                            Two stages spectrometer
                                                               Large Angle Spectrometer (SM1)
                                                               Small Angle Spectrometer (SM2)

                                                            Hadron & Muon high energy beams.
                                                            Beam rates: 108 muons/s, 5·107
                                                                hadrons/s.
     SPIN – Praha – 2007, July 08-14                        Bakur Parsamyan                      9
Polarized target


                                                          2002-2004 6LiD:
                                                          Target Polarization ±50%
                                                          dilution factor f ≈ 0.4
              superconductive                             ~20% of the time transversely polarized
      Solenoid (2.5 T) Dipole (0.5 T)
                                                                 For transverse runs polarization reversal
                                                                 in two cells each ~ 5days



          Two 60 cm long 6LiD cells with opposite polarization




                                                 Data collected simultaneously for the two target spin orientations.

                                                           Longitudinal polarization    Transverse polarization




   SPIN – Praha – 2007, July 08-14                                            Bakur Parsamyan                     10
Event selection (2002-2004 deuteron data)
   DIS cuts :                All Hadrons :
       Q2 > 1 GeV2               z > 0.2
       0.1 < y < 0.9             pt > 0.1 GeV/c
       W > 5 GeV

Year      Period     Positive hadrons    Negative hadrons

2002     P2B/P2C         0.71·106            0.59·106

2002       P2H           0.48·106            0.40·106

2003     P1G/P1H         2.46·106            2.03·106

2004     W33/W34         2.12·106            1.74·106

2004     W35/W36         2.75·106            2.26·106
Sum                      8.52·106            7.02·106




       SPIN – Praha – 2007, July 08-14                      Bakur Parsamyan   11
Extraction of the asymmetries
d   d 
             AU i((L)hT,raw i  1,..,5 (i  6,..,8)
               w            s)

d   d 
                          ,


AUT(,h ,s )  Dwi (h ,s ) ( y) f ST AUT(h ,s ) , (i  1,..,5)
 wi
     raw
                                         wi
                                                                                  The number-of-event

ALT(,h ,s )  Dwi (h ,s ) ( y) fP ST ALT(h ,s ) , (i  6,..,8)
 wi
     raw                             beam
                                          wi                                           asymmetries

                                                                                        1   h   s
8 modulations           5 combinations of φh and φS
                                                                                         2  h  s
                                                         Independent angles              3  3 h   s
                                                                                         4  s

                 w1 (h , s )                  w6 (h , s )
                                                                                         5  2 h   s
W1 (1 )  A     UT , raw        sin(1 )  A   LT , raw        cos(1 )
             w2 h ,
W2 ( 2 )  AUT (,raws ) sin( 2 )
W3 ( 3 )  AUT (,h ,s ) sin( 3 )
             w3
                  raw
                                                                                         Azimuthal
                                                                                        modulations
                  w4 (h , s )                   w7 ( h , s )
W4 ( 4 )  A     UT , raw        sin( 4 )  A   LT , raw         cos( 4 )
                                        w8 h ,
W5 ( 5 )  AUT (,h ,s ) sin( 5 )  ALT (,raws ) cos( 5 )
             w5
                  raw


      SPIN – Praha – 2007, July 08-14                                          Bakur Parsamyan             12
Double Ratio method (NP B765 (2007) 31)
For each data taking period, each cell and polarization state the Φj distribution of the number of
events can be presented like:
                                                                        u - Up Stream cell, d - Down Stream cell,
                              
        N  u/d   ( j )  N    0u / d   ( j )(1  Wj ( j ))           +/- - target polarization

                                                                            
                                                                N u ( j ) N d (  j )
“ratio product” quantities                        F ( j )                 
                                                                N u ( j ) N d (  j )
Under the reasonable assumption on the ratio of the acceptances -
to be constant before and after polarization reversal in each Φj bin:

                         
         au ( j )       au ( j )
           
                         
                                       const          Acceptance differences cancel out
         a ( j )
           d             a ( j )
                          d


                                
                   N u (  j ) N d ( j )
      F ( j )                  
                                             1  4W j ( j )
                   N ( j ) N ( j )
                     u            d


  minimizes acceptance effects
  spin independent terms cancel at 1st order (Cahn)


    SPIN – Praha – 2007, July 08-14                                        Bakur Parsamyan                          13
1-D fitting procedure (MINUIT with  2 minimization method)

9 – XBj, 8 – z, 9 - PhT bins and 16 Φj bins.
                                                                         
                                                             N u ( j ) N d (  j )
Fitting the “ratio product”                     F ( j )                
                                                             N u ( j ) N d (  j )

quantities                                                   1          1          1           1
                                           R ( j )      
                                                                                       
                                                         N u ( j ) N u ( j ) N d (  j ) N d (  j )

   in case if W j ( j ) contains only sin or only cos moment.
   by F ( j )  par[0](1  4 par[1] sin( j )), or by F ( j )  par[0](1  4 par[1] cos( j ))


                                                          par[1] - Raw Asymmetry value.

                 and in case if W j ( j ) contains both sin and cos moments.
  by F ( j )  par[0](1  4( par[1] sin( j )  par[2] cos( j )))

        par[1] - "sin" Raw Asymmetry value and par[2] - "cos" Raw Asymmetry.

Newly extracted Collins & Sivers asymmetries gave the same result as published (NP B765 (2007) 31)

      SPIN – Praha – 2007, July 08-14                                      Bakur Parsamyan               14
Systematic checks

    Periods compatibility
         Asymmetries from each period were compared with the weighed
          mean from all periods.
    Par[0] test
         Extracted from the fit par[0] ≈ 1 (acceptance cancellation)
    Stability of the acceptance in Φj angles
                              
                  N u ( j ) N d (  j )
     R ( j )                
                                           const ( j ) (acceptance assumption)
                  N ( j ) N (  j )
                    u          d


    The quality of the fit
        2 - distribution




               Systematic errors are smaller than statistical

     SPIN – Praha – 2007, July 08-14                             Bakur Parsamyan   15
2-D fitting procedure (9 parameter fit using MINUIT)
  9 – XBj, 8 - z, 9 - PhT bins and 8x8 – φh,φS bins.

                                          Fitting function
F (h ,  s )  par[0](1  4( par[1] sin(h   s )  par[2] sin(3h   s ) 
                par[3] sin(h   s )  par[4] sin(2h   s )  par[5] sin  s 
                par[6] cos(h   s )  par[7] cos(2h   s )  par[8] cos  s ))
 Fitting the “ratio product” quantities
                                                   Nu (h , S ) N d (h , S )
                                                                  
                                                 F 
                                                   Nu (h , S ) N d (h , S )
                                                                   


                                                     1                   1                    1                    1
                                         R                                                           
                                                Nu (h , S )
                                                 
                                                                    Nu (h , S )
                                                                     
                                                                                        N d (h , S )
                                                                                          
                                                                                                             N d (h , S )
                                                                                                               




by F ( h ,  S )  par[0](1  4( par[i ] sin( i )  par[ j ] cos( j )))


                                       ,.., par[i],..., par[ j ],..                        Raw Asymmetries
Results from 1D and 2D fits are in good agreement, only 1D results have been released
     SPIN – Praha – 2007, July 08-14                                         Bakur Parsamyan                                  16
Correlation Coefficients (positive hadrons, x)
             covarinace[i, j]
                                      i, j = 1,..,8
       variance[i,i]  variance[j, j]
                                                        - Correlation between Collins and Sivers asymmetries

   For the most of the pairs of parameters
    ρ≈0 and always < 0.4
   Only some correlation coefficients are
    larger than 0.1
   Correlations are small or negligible




                                                                                   preliminary


                                                                                                               x
     SPIN – Praha – 2007, July 08-14                                   Bakur Parsamyan                         17
Correlation Coefficients (+/- hadrons, x, z and PT)




   SPIN – Praha – 2007, July 08-14         Bakur Parsamyan   18
                     sin(3 h  s )    sin( s )
Results for        A UT                &A
                                        UT        (2002-2004 deuteron data, 1D fit)




   SPIN – Praha – 2007, July 08-14                       Bakur Parsamyan              19
                   sin(2 h  s )    cos( h  s )
Results for A      UT                &A
                                      LT          (2002-2004 deuteron data, 1D fit)




   SPIN – Praha – 2007, July 08-14                       Bakur Parsamyan              20
                      cos( s )       cos(2 h  s )
Results for        A  LT             &A
                                      LT              (2002-2004 deuteron data, 1D fit)




   SPIN – Praha – 2007, July 08-14                          Bakur Parsamyan               21
   cos( h  s )
A  LT                   asymmetry (PRD73:114017,2006)
First estimations by A.Kotzinian & P.Mulders, PRD 54, 1229 (1996)
A.Kotzinian, B.Parsamyan & A.Prokudin, PRD73:114017,(2006)


    Lorentz Invariance Relations:                                           Deuteron
                                                                            Proton

                  d q(1)
    g2 ( x) 
     q
                     g1T ( x)
                  dx
                          1
                               g1q ( y )
    gq (1)
     1T      ( x, k )  x  dy
                  2
                  T
                          x
                                  y


                                                                            Deuteron
    Predicted for COMPASS kinematical range and                             Proton
                   cos(  )
 deuteron target ALT h s asymmetry is small ≈ 1-2%

    Measured      ALT h s ) is small, compatible with zero.
                   cos(




     SPIN – Praha – 2007, July 08-14                                Bakur Parsamyan    22
ALT asymmetry (COMPASS) PRD73:114017,(2006)




Predicted dependence of ALT h S ) on x, y and z with P ,min  0.5 GeV / c for COMPASS
                         cos(
                                                         hT

Kinematical cuts: Q2>1.0 (GeV/c)2, W2>25 GeV2, 0.05<xBj<0.6, 0.5 < y < 0.9, 0.4 < z < 0.9


                   cos( h  s )
 The predicted ALT          asymmetries are small (few % for deuteron target) in COMPASS
“preferable” (with sizable statistics) kinematical regions.


     SPIN – Praha – 2007, July 08-14                                    Bakur Parsamyan     23
ALT asymmetry (HERMES & JLab) PRD73:114017,(2006)




Predicted dependence of ALT h S ) on x, y and z with PhT ,min  0.5 GeV / c for HERMES and JLab
                         cos(



Kinematical cuts (HERMES): - Q2>1.0 (GeV/c)2, W2>10 GeV2, 0.1<xBj<0.6, 0.45 < y < 0.85, 0.4 < z < 0.9
Kinematical cuts (JLab): - Q2>1.0 (GeV/c)2, W2>4 GeV2, 0.2<xBj<0.6, 0.4 < y < 0.7, 0.4 < z < 0.7

                    cos( h  s )
 The predicted ALT         asymmetries can reach up to ~10% for proton target and up to ~6-7% for
deuteron target with high x, y, z and pT cuts at HERMES and JLab kinematics.


      SPIN – Praha – 2007, July 08-14                                    Bakur Parsamyan                24
Conclusions

     6 new asymmetries were measured in COMPASS (2002-2004
      deuteron data)
        sin(3h  s )     sin  s     sin(2h  s )    cos(h s )       cos  s       cos(2h s )
      A UT               ,AUT        ,AUT               ,A
                                                         LT             , A LT        &A  LT

     Analysis was done using 1 dimensional and 2 dimensional fitting
      procedures
     Asymmetries obtained from both methods are in agreement and
      point to the same physical result.
          Only 1D results have been released
     Correlation coefficients obtained from 2 dimensional fit are negligible
      or small
          In most of the cases ρ ≈ 0 and always < 0.4
     Results have been checked for systematic effects
          Systematical errors appears to be smaller than statistical
     All measured asymmetries are compatible with zero within statistical
      accuracy…


     SPIN – Praha – 2007, July 08-14                                    Bakur Parsamyan                   25
The end




                            Thank you!!!




   SPIN – Praha – 2007, July 08-14     Bakur Parsamyan   26
Additional slides




   SPIN – Praha – 2007, July 08-14   Bakur Parsamyan   27
ALT asymmetry PRD 54, 1229 (1996)

                                         1     d   d                    H g1T
             A ( x, y, z, PhT ,  ) 
               h                   h
                                                             D( y ) cos(s )
                                                                           h
                                                                                      ...
                                      l ST d  d
                                                        
               LT                  s       N
                                                                               H f1

           First estimations by A.Kotzinian & P.Mulders, PRD 54, 1229 (1996)


| PhT |
                                                 PhT
                                         d PT  M cos(s )(d  d )
                                               2              h          
                                                                                         eq2 g1qT(1) ( x) Dqh ( z)
        cos(sh ) ALT
                   h
                        ( x, y, z )  2                                        2 zD( y) q 2 q
  M                                             d 2 PT  (d   d  )                eq f1 ( x) Dqh ( z)
                                                                                                 q

              Weighted asymmetry is related to the first kT-momentum of g1T:
                                                  2
                                                kT q
                              g ( x)   d kT
                                       q (1)
                                       1T            g1T ( x, kT2 )
                                                       2

                                              2M 2
               There exists a relation between first momentum of g1T and g2
                 (follows from Lorentz invariance, Tangerman & Mulders) :
                        x                          1                   q                     1
                                                                      g1 ( y)
     g1T(1) ( x)   g 2 ( y)dy    g 2 ( y)dy  (WW  appr )  x 
      q                q                q
                                                                              dy
                   0                x                               x
                                                                         y
                        All ingredients (DFs & FFs) are known!
     SPIN – Praha – 2007, July 08-14                                       Bakur Parsamyan                       28
 ALT asymmetry PRD73:114017,(2006)
  A.Kotzinian, B.Parsamyan & A. Prokudin, Phys.Rev. D73 (2006)
                                                         2
                                       1                kT                         From analysis of unpolarized
 f ( x, k )  f ( x)
   q         2        q
                                            exp(              ),
  1          T       1
                                  0
                                    2
                                                     0      2
                                                                                   PhT dependence and Cahn effect
                                                           2
                                        1                PhT
D ( z, P )  D ( z )
   h          2        h
                                                exp(            ),
   q         hT        q
                                          2
                                            D               2
                                                             D             0  0.25(GeV / c) 2 ,  D  0.2(GeV / c) 2
                                                                            2                       2
                                                    2
                                                   kT
g ( x, k )  g ( x) N exp(
  q          2        q
                                                         )                                              kT q
  1T         T        1T
                                                   12                   Naïve positivity constraint:      g1T ( x, kT2 )  f1q ( x, kT2 )
 N is fixed by                                                                                          M
                                                  holds if 1  0.246 (GeV/c)
                             2                                2                  2
                            kT
g1qT(1) ( x)   d 2 kT                    2
                                g1qT ( x, kT )
                          2M 2                    Predictions done for:
                                                2
                               2M 2            kT
g1T ( x, kT )  g1T ( x)
  q          2        q (1)
                                        exp( 2 )                12  0.1, 0.15 and 0.25(GeV / c) 2
                                    4
                                            1                     1

                                                                  2  y Mz PhT                        2
                                                                                                    PhT
                                                                                                        2 2  q 1T
                                  2                                                      exp( 2                              h
                                                                                                            ) e2 g q (1) ( x) Dq ( z )
                                      dh (d  d ) cos h
                                            S           S
                                                                   xy (  D  1 z )
                                                                            2       2 2 2
                                                                                                 D  1 z q
ALT h ( x, y, z, PhT )  2
       S
 cos                          0
                                         2
                                                              2
                                                                 1  (1  y ) 2                          2
                                       0 dh (d  d )
                                                                                 1                 PhT
                                                                                                           2 2  q 1
                                              S
                                                                                            exp( 2                             h
                                                                                                              ) e2 f q ( x) Dq ( z )
                                                                      xy 2
                                                                                 D  0 z
                                                                                  2     2 2
                                                                                                   D  0 z q


           SPIN – Praha – 2007, July 08-14                                                     Bakur Parsamyan                          29
ALT asymmetry, kinematical cuts PRD73:114017,(2006)



                                               High
                       Low         +        x, y, z & pT
                    x, y, z & pT
 ATMD=
                        Low
                                                 High
                   x, y, z & pT         +
                                              x, y, z & pT




GRV98+GRSV2000 LO, std DFs Kretzer FFs
COMPASS - Q2>1.0 (GeV/c)2, W2>25 GeV2, 0.05<xBj<0.6, 0.5 < y < 0.9, 0.4 < z < 0.9, |Ph,T| > 0.5GeV/c

HERMES - Q2>1.0 (GeV/c)2, W2>10 GeV2, 0.1<xBj<0.6, 0.45 < y < 0.85, 0.4 < z < 0.9, |Ph,T| > 0.5GeV/c

JLab - Q2>1.0 (GeV/c)2, W2>4 GeV2, 0.2<xBj<0.6, 0.4 < y < 0.7, 0.4 < z < 0.7, |Ph,T| > 0.5GeV/c



     SPIN – Praha – 2007, July 08-14                                     Bakur Parsamyan               30

								
To top