References - Bogoliubov Laboratory of Theoretical Physics - JINR

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In summary, we made measurements on the longitudinal spin transfer to Λ and ¯ Λ hyperons in √ s = 200 GeV polarized proton-proton collisions for hyperon pT up to 4GeV/c. The spin transfer is found to be DLL = −0.03±0.13(stat)±0.04(syst) for Λ and DLL = −0.12±0.08(stat)±0.03(syst) for ¯ Λhyperonswith〈η〉 =0.5and〈pT〉 =3.7GeV/c. The measurements of the transfer spin transfer may provide access to transversity distribution of the nucleon, and feasibility studies have started. References [1] D. Buskulic et al. [ALEPH Collaboration], Phys. Lett. B 374, 319 (1996). K. Ackerstaff et al. [OPAL Collaboration], Eur. Phys. J. C 2, 49 (1998). P. Astier et al. [NOMAD Collaboration], Nucl. Phys. B 588, 3 (2000); 605, 3 (2001). M.R. Adams et al. [E665 Collaboration], Eur. Phys. J. C 17, 263 (2000). M. Alekseev et al. [COMPASS Collaboration], arXiv:0907.0388 [hep-ex]. A. Airapetian et al. [HERMES Collaboration], Phys.Rev. D 64, 112005 (2001); 74, 72004 (2006). [2] B.I.Abelevet al. [STAR Collaboration], arXiv:0910.1428 [hep-ex]. [3] B.I.Abelevet al. [STAR Collaboration], Phys. Rev. C 75, 064901 (2007). [4] D. de Florian, M. Stratmann and W. Vogelsang, Phys. Rev. Lett. 81, 530 (1998) and W. Vogelsang, private communication (2009). [5] C. Boros, J.T. Londergan and A.W. Thomas, Phys. Rev. D 62, 014021 (2000). [6] B.Q. Ma, I. Schmidt, J. Soffer and J.J. Yang, Nucl. Phys. A 703, 346 (2002). [7] Q.H. Xu, C.X. Liu and Z.T. Liang, Phys. Rev. D 65, 114008 (2002). Q.H. Xu, Z.T. Liang and E. Sichtermann, Phys. Rev. D 73, 077503 (2006); Y. Chen et al., ibid. 78, 054007 (2008). [8] C. Amsler et al. [Particle Data Group], Phys. Lett. B 667, 1 (2008). [9] K. H. Ackermann et al. [STAR Collaboration], Nucl. Instrum. Meth. A499, 624 (2003). [10] O. Jinnouchi et al., arXiv:nucl-ex/0412053. [11] J. Kiryluk [STAR Collaboration], arXiv:hep-ex/0501072. [12] B. I. Abelev et al. [STAR Collaboration], Phys. Rev. Lett. 97, 252001 (2006). B. I. Abelev et al. [STAR Collaboration], Phys. Rev. Lett. 100, 232003 (2008). [13] A. Bravar et al. [E704 Collaboration], Phys. Rev. Lett. 78, 4003 (1997). [14] J. C. Collins, S. F. Heppelmann and G. A. Ladinsky, Nucl. Phys. B 420, 565 (1994). 318
LONGITUDINAL SPIN TRANSFER OF THE Λ AND ¯ Λ HYPERONS IN DIS AT COMPASS V.L. Rapatskiy 1 on behalf of the COMPASS collaboration (1) Joint Institute for Nuclear Research, 141980, Russia, Moscow reg., Dubna E-mail: rapatsky@cern.ch Abstract The longitudinal spin transfer from muons to Λ and ¯ Λ hyperons has been studied in deep inelastic scattering off an unpolarized isoscalar target at the COMPASS experiment at CERN. The spin transfers to Λ and ¯ Λ produced in the current fragmentation region exhibit different behaviors as a function of x and xF . The resulting average values are DΛ LL = −0.01 ± 0.05 ± 0.02 and D ¯ Λ LL =0.25 ± 0.06 ± 0.05. These results are discussed in the frame of recent model calculations. Interest to study the polarization of Λ and ¯ Λ in DIS resides in the possibility of accessing the distributions of strange quarks and antiquarks in nucleon (s(x) and¯s(x)). The present results are based on the analysis of data collected by COMPASS during the years 2003-2004. The Λ and ¯ Λ hyperons were produced by scattering 160 GeV polarized μ + off a polarized 6 LiD target. The COMPASS spectrometer is described in [1]. The average beam polarization was Pb = −0.76 ± 0.04 in the 2003 run and Pb = −0.80 ± 0.04 in the 2004 run. The cryogenic target consists of two 60 cm long cells filled with 6 LiD, which is characterized by high polarizability. Both cells are oppositely polarized, the polarization vector is reversed every 8 hours. DIS events are selected by cuts on the photon virtuality (Q 2 > 1(GeV/c) 2 )andonthe fractional energy of the virtual photon (0.2
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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
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SPIN CORRELATIONS OF THE ELECTRON A
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the two-photon system equaling 1).
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ANOTHER NEW TRACE FORMULA FOR THE C
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Compare the gain of time and effort
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where the triplet and octet axial c
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[2] Y. Prok et al. [CLAS Collaborat
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Melosh rotations which boost the re
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ky �GeV� 0.4 0.2 0.0 �0.2 �
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[2] B. Pasquini, and S. Boffi, Phys
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The appearance of both |+〉 and |
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2.2 Intrinsic Transverse Motion Qua
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are still complex: for a given corr
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This last is required to complete t
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[16] P.G. Ratcliffe and O.V. Teryae
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Figure 1: a)[left] μpG p E /Gp M (
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4 Conclusion We introduced a simple
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√ δΔq8 x for Δq8 and γΔGx fo
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understanding of polarized light qu
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They are inverse powers of Q 2 kine
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accounts approximately for the TM a
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POTENTIAL FOR A NEW MUON g-2 EXPERI
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When the momentum increases (p >p0)
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EVOLUTION EQUATIONS FOR TRUNCATED M
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4 Perspectives Evolution equations
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NEW DEVELOPMENTS IN THE QUANTUM STA
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statistical approach compared to th
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POLARIZED HADRON STRUCTURE IN THE V
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g 3 A =Δuv(Q 2 ) − Δdv(Q 2 ), g
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AXIAL ANOMALIES, NUCLEON SPIN STRUC
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3. Vector current of strange quarks
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ORBITAL MOMENTUM EFFECTS DUE TO A L
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The elastic scattering S-matrix in
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IDENTIFICATION OF EXTRA NEUTRAL GAU
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for final l + l − events (l = μ,
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QUARK INTRINSIC MOTION AND THE LINK
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where wP = − m 2M 2 −p1 cos ω
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where g q 2x − ξ 1(x, pT )= πM2
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EXPERIMENTAL RESULTS
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01 00 11 01 01 01 00 11 01 01 01 00
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where C1, C2 and A1 - signals from
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Figure 1: Layout of experiment targ
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According to requirements of the de
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Electron energy is measured at ATLA
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Fig. 2 shows the results of the lon
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e γ* e’ x+ ξ x− ξ A A’ e e
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cos 0φ C A φ cos C A cos 2φ C A
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5 Summary HERMES has measured signi
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(1.205 ± 0.0012) GeV/c, 10 10 p/s,
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was done in the interval ”−t”
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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
Page 270 and 271: original software packages (MC simu
Page 272 and 273: MEASUREMENTS OF TRANSVERSE SPIN EFF
Page 274 and 275: to “near-side” and “away-side
Page 276 and 277: THE FIRST STAGE OF POLARIZATION PRO
Page 278 and 279: In paper [12] the study was made of
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Page 282 and 283: Table 2: The parameters of the main
Page 284 and 285: POLARIZATION MEASUREMENTS IN PHOTOP
Page 286 and 287: With a polarized electron beam inci
Page 288 and 289: Figure 3: Preliminary helicity asym
Page 290 and 291: INVESTIGATION OF DP-ELASTIC SCATTER
Page 292 and 293: framework with the use of deuteron
Page 294 and 295: SPIN PHYSICS WITH CLAS Y. Prok 12,
Page 296 and 297: 1.3 Flavor Decomposition of the Hel
Page 298 and 299: Γ p 1 0.15 0.125 0.1 0.075 0.05 0.
Page 300 and 301: The upcoming energy upgrade of Jeff
Page 302 and 303: y the nearly 1000 combined citation
Page 304 and 305: � R = −Pt/Pl τ(1 + ε)/2ε; he
Page 306 and 307: 4 Results of GEp-III Experiment In
Page 308 and 309: 6 Theoretical Developments The earl
Page 310 and 311: lz = 0 (along the direction of the
Page 312 and 313: models have recently been challenge
Page 314 and 315: [32] Chung P. L. and F. Coester, Ph
Page 316 and 317: 48 ± 3% for two beams. The proton
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Page 324 and 325: The sensitivity of the data to the
Page 326 and 327: COMPASS could be converted into a f
Page 328 and 329: 3.1.2 Beam charge and spin asymmetr
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Page 332 and 333: References [1] D. Mueller et al, Fo
Page 334 and 335: l’ l p q p h H (z) 1 h (x) 1 l l
Page 336 and 337: 3. Data selection. The data selecti
Page 338 and 339: φ sin3 a 0.06 0.04 0.02 0 -0.02 -0
Page 340 and 341: TRANSVERSE SPIN AND MOMENTUM EFFECT
Page 342 and 343: model. Both the cos φh and the cos
Page 344 and 345: D cos φ A 0 -0.1 -0.2 -0.3 + h -2
Page 346 and 347: 4.3 The Sivers asymmetry According
Page 348 and 349: [3] A. Airapetian et al. [HERMES co
Page 350 and 351: 2. Delta-Sigma Experimental Set-up.
Page 352 and 353: 6. Estimate of the count rate in tr
Page 354 and 355: 2 Analysis Formalism Spin-dependent
Page 356 and 357: The MC production comprises three s
Page 358 and 359: 6 High pT hadron pair analysis for
Page 360 and 361: [2] V. Y. Alexakhin et al. [COMPASS
Page 362 and 363: 2 Towards polarized Antiprotons For
Page 364 and 365: 4 Spin-Filtering Experiments at COS
Page 366 and 367: to test the theoretical models of t
Page 368 and 369: 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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