References - Bogoliubov Laboratory of Theoretical Physics - JINR

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Concerning the strange quark and antiquark distributions, a careful analysis of the NuTeV CCFR data led us to the conclusion that s(x, Q 2 ) �= ¯s(x, Q 2 ) and the corresponding polarized distributions are unequal, small and negative [11], as shown in Fig. 5. The rapid rise one observes in the small x region is compatible with the data from Hermes, as shown in Fig. 6. Finally let us recall that the subject of quark and antiquark transversity distribution in the proton is also a very interesting topic. By studying a possible connection between helicity and transversity, we have proposed a simple toy model (see Ref. [13]). Acknowledgments I am grateful to the organizers of DSPIN09 for their warm hospitality at JINR and for their invitation to present this talk. My special thanks go to Prof. A.V. Efremov for providing a full financial support and for making, once more, this meeting so successful. References [1] C. Bourrely, F. Buccella, J. Soffer, Euro. Phys. J. C23 (2002) 487. For a practical use of these PDF, we refer the reader to the following web site: www.cpt.univ-mrs.fr/∼ bourrely/research/bbs-dir/bbs.html. [2] C. Bourrely, F. Buccella, J. Soffer, Mod. Phys. Letters A18 (2003) 771. [3] C. Bourrely, F. Buccella, J. Soffer, Euro. Phys. J. C41 (2005) 327. [4] C. Bourrely, F. Buccella, J. Soffer, (in preparation). [5] C. Bourrely, F. Buccella, J. Soffer, Mod. Phys. Letters A21 (2006) 143. [6] F.D. Aaron, et al., H1 Collaboration, DESY-09-005, arXiv:0904.3513 [hep-ex], to appear EPJC. [7] A.M.Cooper-Sarkaretal., Z.Phys.C39, (1988) 281. [8] H1 Collaboration, submitted to DIS 2009, Madrid, Spain, April 26-30 (2009). [9] S. Chekanov, et al., ZEUS Collaboration, Phys. Lett. B682 (2009) 8. [10] S. Chekanov, et al., ZEUS Collaboration, Euro. Phys. J. C62 (2009) 625. [11] C. Bourrely, F. Buccella, J. Soffer, Phys. Lett. B648 (2007) 39. [12] A. Airapetian, et al., Hermes Collaboration, Phys. Lett. B666 (2008) 446. [13] C. Bourrely, F. Buccella, J. Soffer, Mod. Phys. Letters A24 (2009) 1889. 142
POLARIZED HADRON STRUCTURE IN THE VALON MODEL AND THE NUCLEON AXIAL COUPLING CONSTANTS: a3 AND a8 F. Taghavi Shahri 1 † ,F.Arash 2 (1) School of Particles and Accelerators, Institute for Research in Fundamental Sciences (IPM) P.O. Box 19395-5531, Tehran, Iran (2) Physics Department, Tafresh University, Tafresh, Iran † E-mail: f taghavi@ipm.ir Abstract We have utilized the concept of valon model to calculate the spin structure function of the nucleon. The structure of the valon itself developed through the perturbative dressing of a valence quark in QCD, which is independent of the hosting hadron. In this paper we calculate the nucleon axial coupling constants, a3 and a8 in the valon framework. We compare the results with experimental data and find good agreement between them. 1 Polarized hadron structure in the Valon model One of the fundamental properties of the nucleon is its spin. The spin structure of nucleon has been the subject of heated debates over the past twenty years. The key question is that how the spin of the nucleon is distributed among its constituent partons. Any determination of parton distribution function in a nucleon in the framework of QCD always involves some model-dependent procedures. We utilized the valon model [1] to study polarized nucleon structure. In the valon model, it is assumed that a nucleon is composed of three dressed valence quarks: the valons. Each valon has its own internal structure which can be probed at high enough Q 2 . At low Q 2 , a valon behaves as a valence quark. The valons play a role in scattering problems as the constituents do in bound state problems. It is assumed that the valons stand at a level in between hadrons and partons and that the valon distributions are independent of the probe or Q 2 . In this representation a valon is viewed as a cluster of its own partons. The evolution of the parton distributions in a hadron is effected through the evolution of the valon structure, as the higher resolution of a probe reveals the parton content of the valon. The valon model is essentially a two component model. In this framework, the helicity distributions of various partons in a hadron are given by: δq h i (x, Q2 )= � � 1 dy x y δGhvalon (y)δqvalon i ( x y ,Q2 ) (1) where δGh valon (y) is the helicity distribution of the valon in the hosting hadron. It is related to unpolarized valon distribution by: δGj(y) =δFj(y)Gj(y). (2) 143
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XIII Advanced Research Workshop on
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ã�� [539.12.01 + 539.12 ... 14
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Analytic perturbation theory and pr
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Measurements of GEp/GMp to high Q 2
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WELCOME ADDRESS Alexei Sissakian Di
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he joined the group of prof. Przemy
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proton. Dividing these 90 ◦ cm p-
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p-p scattering angle fixed at exact
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tuning for each ring. The Workshop
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was only about 10 5 per second, but
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[10] E.F. Parker et al., Phys. Rev.
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MICROSCOPIC STERN-GERLACH EFFECT AN
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DeGrand-Miettinen model predicted P
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TOWARDS STUDY OF LIGHT SCALAR MESON
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104xdBR(φ--> π η 0 -1 γ )/dm, G
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RECURSIVE FRAGMENTATION MODEL WITH
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Figure 2: String decaying into pseu
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pT -distributions in the quark frag
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4 Inclusion of spin-1 mesons For a
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CONSTITUENT QUARK REST ENERGY AND W
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〈r 2 ch 〉≈1fm2 . Now with Eqs
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TOWARDS A MODEL INDEPENDENT DETERMI
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Common for the difference cross sec
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TRANSVERSITY GPDs FROM γN → πρ
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The scattering amplitude of the pro
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INFRARED PROPERTIES OF THE SPIN STR
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5 Acknowledgement B.I. Ermolaev is
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We shall call this model the “sec
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y f ν V = f l V = f u V = f d gz V
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2. We remind, that the celebrated G
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of the resonance A, θV � 39 o .
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• Right-handed EW currents. The c
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pesum- (p Entries 0 + pe)-(p-pe) Me
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CROSS SECTIONS AND SPIN ASYMMETRIES
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R(ρ) 5 4 3 2 1 0 2 3 4 5 6 7 8 9 1
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TWO-PHOTON EXCHANGE IN ELASTIC ELEC
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and depend on three parameters : fN
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O(αs) SPIN EFFECTS IN e + e −
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3 Polarization results for mq → 0
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Since one has (↑↓) pc Born =(
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Figure 1: A typical lowest order Fe
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sin φ S (π + ) A UT 1.0 0.8 0.6 0
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form the agreement with these data
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in settling this dynamical issue. G
Page 93 and 94: SPIN CORRELATIONS OF THE ELECTRON A
Page 95 and 96: the two-photon system equaling 1).
Page 97 and 98: ANOTHER NEW TRACE FORMULA FOR THE C
Page 99 and 100: Compare the gain of time and effort
Page 101 and 102: where the triplet and octet axial c
Page 103 and 104: [2] Y. Prok et al. [CLAS Collaborat
Page 105 and 106: Melosh rotations which boost the re
Page 107 and 108: ky �GeV� 0.4 0.2 0.0 �0.2 �
Page 109 and 110: [2] B. Pasquini, and S. Boffi, Phys
Page 111 and 112: The appearance of both |+〉 and |
Page 113 and 114: 2.2 Intrinsic Transverse Motion Qua
Page 115 and 116: are still complex: for a given corr
Page 117 and 118: This last is required to complete t
Page 119 and 120: [16] P.G. Ratcliffe and O.V. Teryae
Page 121 and 122: Figure 1: a)[left] μpG p E /Gp M (
Page 123 and 124: 4 Conclusion We introduced a simple
Page 125 and 126: √ δΔq8 x for Δq8 and γΔGx fo
Page 127 and 128: understanding of polarized light qu
Page 129 and 130: They are inverse powers of Q 2 kine
Page 131 and 132: accounts approximately for the TM a
Page 133 and 134: POTENTIAL FOR A NEW MUON g-2 EXPERI
Page 135 and 136: When the momentum increases (p >p0)
Page 137 and 138: EVOLUTION EQUATIONS FOR TRUNCATED M
Page 139 and 140: 4 Perspectives Evolution equations
Page 141 and 142: NEW DEVELOPMENTS IN THE QUANTUM STA
Page 143: statistical approach compared to th
Page 147 and 148: g 3 A =Δuv(Q 2 ) − Δdv(Q 2 ), g
Page 149 and 150: AXIAL ANOMALIES, NUCLEON SPIN STRUC
Page 151 and 152: 3. Vector current of strange quarks
Page 153 and 154: ORBITAL MOMENTUM EFFECTS DUE TO A L
Page 155 and 156: The elastic scattering S-matrix in
Page 157 and 158: IDENTIFICATION OF EXTRA NEUTRAL GAU
Page 159 and 160: for final l + l − events (l = μ,
Page 161 and 162: QUARK INTRINSIC MOTION AND THE LINK
Page 163 and 164: where wP = − m 2M 2 −p1 cos ω
Page 165 and 166: where g q 2x − ξ 1(x, pT )= πM2
Page 167: EXPERIMENTAL RESULTS
Page 170 and 171: 01 00 11 01 01 01 00 11 01 01 01 00
Page 172 and 173: where C1, C2 and A1 - signals from
Page 174 and 175: Figure 1: Layout of experiment targ
Page 176 and 177: According to requirements of the de
Page 178 and 179: Electron energy is measured at ATLA
Page 180 and 181: Fig. 2 shows the results of the lon
Page 182 and 183: e γ* e’ x+ ξ x− ξ A A’ e e
Page 184 and 185: cos 0φ C A φ cos C A cos 2φ C A
Page 186 and 187: 5 Summary HERMES has measured signi
Page 188 and 189: (1.205 ± 0.0012) GeV/c, 10 10 p/s,
Page 190 and 191: was done in the interval ”−t”
Page 192 and 193: If we admit a non-zero quark transv
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which is trivial in collinear LO ap
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In figure 3 the expected errors on
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[12] A. V. Efremov and O. V. Teryae
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Figure 1: The COMPASS spectrometer.
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Comparing this formula to the inclu
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Figure 5: Comparison of COMPASS inc
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[9] B. Adeva et al. (SMC Coll.), Ph
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q T sin( φ-φ ) M AUT 0.14 0.12 0.
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proton beam is planned. References
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Run Year √ s (GeV) Polarization R
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ackground fraction, and asymmetry i
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At √ s = 200 GeV, ALL(pp → π
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[6] D. de Florian, W. Vogelsang, an
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higher energies, where the cross se
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Figure 3: The experimental results
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kinematic range to low values of Bj
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3 Semi-Inclusive DIS Collins and Si
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Unpolarized target asymmetries. The
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4 Summary Since the end of data-tak
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polarization as well as a construct
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Finally the COMPASS reconstruction
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tained in the NLO QCD approximation
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with only modern NN potential are r
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(a) (b) Figure 3: (a) T20 data take
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of electroproduction from polarized
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As is seen in Fig. 1 values of the
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SEMI-INCLUSIVE DIS AND TRANSVERSE M
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The yellow band in Fig. 1 is the re
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At leading twist, a third asymmetry
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THE COMPLETION OF SINGLE-SPIN ASYMM
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A N , % 30 20 10 0 0 0.2 0.4 0.6 0.
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Unexpectedly large single spin asym
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THE GENERALIZED PARTON DISTRIBUTION
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, E) H ~ (H, I Im C 5 4 3 2 1 Q = 1
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Reducing to a common denominator (
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LAMBDA PHYSICS AT HERMES S. Belosto
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analysis was carried out reconstruc
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SPIN PHYSICS AT NICA A. Nagaytsev J
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original software packages (MC simu
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MEASUREMENTS OF TRANSVERSE SPIN EFF
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to “near-side” and “away-side
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THE FIRST STAGE OF POLARIZATION PRO
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In paper [12] the study was made of
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emphasis to increase the statistics
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Table 2: The parameters of the main
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POLARIZATION MEASUREMENTS IN PHOTOP
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With a polarized electron beam inci
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Figure 3: Preliminary helicity asym
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INVESTIGATION OF DP-ELASTIC SCATTER
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framework with the use of deuteron
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SPIN PHYSICS WITH CLAS Y. Prok 12,
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1.3 Flavor Decomposition of the Hel
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Γ p 1 0.15 0.125 0.1 0.075 0.05 0.
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The upcoming energy upgrade of Jeff
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y the nearly 1000 combined citation
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� R = −Pt/Pl τ(1 + ε)/2ε; he
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4 Results of GEp-III Experiment In
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6 Theoretical Developments The earl
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lz = 0 (along the direction of the
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models have recently been challenge
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[32] Chung P. L. and F. Coester, Ph
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48 ± 3% for two beams. The proton
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is constant with cos θ∗ , as exp
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In summary, we made measurements on
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angle between the direction of the
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The sensitivity of the data to the
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COMPASS could be converted into a f
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3.1.2 Beam charge and spin asymmetr
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contributions enter only beyond lea
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References [1] D. Mueller et al, Fo
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l’ l p q p h H (z) 1 h (x) 1 l l
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3. Data selection. The data selecti
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φ sin3 a 0.06 0.04 0.02 0 -0.02 -0
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TRANSVERSE SPIN AND MOMENTUM EFFECT
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model. Both the cos φh and the cos
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D cos φ A 0 -0.1 -0.2 -0.3 + h -2
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4.3 The Sivers asymmetry According
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[3] A. Airapetian et al. [HERMES co
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2. Delta-Sigma Experimental Set-up.
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6. Estimate of the count rate in tr
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2 Analysis Formalism Spin-dependent
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The MC production comprises three s
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6 High pT hadron pair analysis for
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[2] V. Y. Alexakhin et al. [COMPASS
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2 Towards polarized Antiprotons For
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4 Spin-Filtering Experiments at COS
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to test the theoretical models of t
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C1 C2 π CH1,2 CH3,4 CH5,6 111 000
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not even resemble the data behavior
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to the slope of the Rosenbluth plot
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The differential cross section of t
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with zero for all mass ranges, with
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more precise and dedicated measurem
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oth types of experiment results are
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is recorded, a good particle identi
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error of the extracted asymmetries
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2.6 Summary and Outlook The first d
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386
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PROTON BEAM POLARIZATION MEASUREMEN
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N A 0.06 0.05 0.04 0.03 0.02 0.01 0
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Intensity profile (arb. units) 1 0.
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[4] H. Okada et al., Proc. of the 1
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The amplitudes of the signals and t
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The following results has been obta
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interaction vanishes and a single Z
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an amorphous NH3 for low and high,
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and depends on a choice of � ℓ1
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3 The conditions for transparent sp
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where angles α and β are defined
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forward angles, where vector Ay and
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espectively. The open symbols repre
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RF dipole (transverse B): εBdl = 1
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i PV / PV i PV / PV 1 0.5 0 -0.5 -1
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The energies of the states Ψ1 −
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field P ≈ +1. If we add the trans
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econstruction provide more accurate
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y detector saturation from pC colli
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2 �p+ 8 He analyzing power measur
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3.3 Effect of valence neutrons on s
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i.e. n0(θ +2π) =n0(θ) . There ar
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w and ˙ɛ. For example, we use par
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436
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REGULARIZATION OF SOURCE OF THE KER
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The corresponding phase transition
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ABOUT SPIN PARTICLE SOLUTION IN BOR
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where the functions fi(s, η) must
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SPINDYNAMICS I.B. Pestov JINR, 1419
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State of hadron matter is defined t
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REMARK ON SPIN PRECESSION FORMULAE
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It is easy to see that for a (massi
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DYNAMICS OF SPIN IN NONSTATIC SPACE
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Schwinger gauge. Probably for the f
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DSPIN-09 WORKSHOP SUMMARY Jacques S
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to some preliminary results reporte
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A new measurement of the polarizati
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new NLO QCD parametrization of the
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Name (Institution, Town, Country) E
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