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6. Estimate of the count rate in transmission measurements using new SPD. An expression for the measured −ΔσL,T (np) value is following −σL,T =ln[(M − T + )/(M + T − )]/(|PBPT |nH), (6.1) where the M + , M − and T + , T − are the statistics for monitor and transmission neutron detectors with the P + B and P − B neutron beam polarizations, respectively. The PT is the polarized proton target polarization value and nH is the number of polarizable hydrogen atoms at polarized proton target. A systematic uncertainty of the −ΔσL,T valueismainlycausedbytheerrorsin|PB|, |PT |, andnH. The statistical error of −ΔσL,T is given by the formula δstat = � (1/M + +1/M − +1/T + +1/T − )/(|PB PT | nH). (6.2) where the M + , M − and T + , T − are the statictics for monitor and transmission neutron detectors with the P + B and P − B neutron beam polarizations, respectively. To estimate the required statistics for the monitor neutron detectors M in order to reach desired value of the ΔσL,T statistical error δstat, we substitute the experimentally obtained nH, |PB|, |PT |, andT/M values [7 - 8] in to this formula: nH =9.14 × 10 23 ; |PB| =0.5; |PT | = 07; T/M =0.82. To reach the δstat value of ∼ 1 mb it is required to accumulate the M statistics equal to ∼ 4.5 × 10 7 counts. From our experience obtained during the np charge-exchange measurements [9 - 10] using high intensity (∼ 2 × 10 10 particles per cycle) unpolarized deuteron beam, such M statistics will be accumulated within 8 hours approximately. Therefore to measure the −ΔσT values at 10 points of the neutron beam energy Tn it is required about ∼ 80 hours of the ”pure” run time for statistics accumulation. The count rate which will be accessible with new source of polarized deuteron ions at the Nuclotron- M estimated above, allows obtaining the −ΔσT values with very high precision [14]. References [1] J. Ball, N.S. Borisov, J. Bystrick´y, A.N. Chernikov et al., In: Proc. Int. Workshop ”Dubna Deuteron- 91”, JINR E2-92-25, p.12, Dubna, 1992. [2] V.I. Sharov, N.G. Anischenko, V.G. Antonenko et al. In: Proc. of the SPIN-PRAHA 2004. Czech. J. Phys. 55, 2005, p.p. A289-A305. [3] F. Lehar, B.Adiasevich, V.P. Androsov et al., Nucl. Instr. Meth. A356, 58 (1995). [4] N. A. Bazhanov et al., Nucl. Instr. Meth. A372, 349 (1996); A402, 484 (1998). [5] I.B. Issinsky et al., Acta Phys. Pol. v. 25, 673 (1994). [6] A. Kirillov, A. Kovalenko et al. Preprint JINR E13-96-210, JINR Dubna, 1996. [7] B.P. Adiasevich, V.G. Antonenko, S.A. Averichev et al., Z. Phys. C71, 65 (1996). [8] V.I. Sharov et al. JINR Rapid Commun. 3[77]-96, 13 (1996); JINR Rapid Commun. 4[96]-99, 5 (1999); Eur. Phys. J. C13, 255 (2000); Eur. Phys. J. C37, 79 ( 2004); Yad. Fiz. 68, 1858 (2005) (Phys. At. Nucl. 68, 1796 (2005)). [9] V.I. Sharov, A.A.Morozov, R.A. Shindin et al. Eur. Phys. J. A39, 267 (2009); Yad. Fiz. 72, No. 6, 1051 (2009) (Phys. At. Nucl. 72, No. 6, 1007 (2009). [10] V.I. Sharov, A.A.Morozov, R.A. Shindin et al. Yad. Fiz. 72, No. 6, 1065 (2009) (Phys. At. Nucl. 72, No. 6, 1021 (2009). [11] V.I. Sharov. Report on the scientific project ”Delta-Sigma experiment”. Dubna, 2009. [12] V.V. Fimushkin, A.S. Belov et al., Eur. Phys. J. ST, v. 162, 275 (2008). [13] L. Sidorin. ”Nuclotron-M project: Status and the nearest plans”. Talk at the LHEP Scientific- Technical Council. April 16, 2009. [14] V.I. Sharov. The new project proposal ”Measurements of the total cross section difference ΔσT (np) and spin-correlation parameter Aoonn(np) at the Nuclotron-M”. (Delta-Sigma-T). Dubna, 2009. 350
COMPASS RESULTS ON GLUON POLARISATION FROM HIGH PT HADRON PAIRS L. Silva On behalf of the COMPASS Collaboration. LIP Lisboa E-mail: lsilva@lip.pt Abstract One of the goals of the COMPASS experiment is the determination of the gluon polarisationΔG/G, for a deep understanding of the spin structure of the nucleon. In DIS the gluon polarisation can be measured via the Photon-Gluon-Fusion (PGF) process, identified by open charm production or by selecting high pT hadron pairs in the final state. The data used for this work were collected by the COMPASS experiment during the years 2002-2004, using a 160 GeV naturally polarised positive muon beam scattering on a polarised nucleon target. A new preliminary result of the gluon polarisation ΔG/G from high pT hadron pairs in events with Q2 > 1(GeV/c) 2 is presented. In order to extract ΔG/G, this analysis takes into account the leading process γq contribution together with the PGF and QCD Compton processes. A new weighted method based on a neural network approach is used. A preliminary ΔG/G result for events from quasi-real photoproduction (Q2 < 1(GeV/c) 2 )isalso presented. 1 Introduction The COMPASS experiment is located in the Super Proton Synchrotron (SPS) accelerator at CERN. For a more complete description of the experimental apparatus the reader is addressed to [1]. In 2007, the COMPASS collaboration estimated the quark contribution to the nucleon spin with high precision [2], using a NLO QCD fit with all world data available. This contribution confirms that approximately 1/3 of the nucleon spin is carried by the quarks, as demonstrated by earlier experiments [3]. The nucleon spin can be written as: 1 2 1 = ΔΣ + ΔG + L (1) 2 ΔΣ and ΔG are, respectively, the quark and gluon contributions to the nucleon spin and L is the orbital angular momentum contribution coming from from the quarks and gluons. The aim of this analysis is to estimate the gluon polarisation, ΔG/G, usingthehigh transverse momentum (high pT ) hadron pairs sample. The analysis is performed in two complementary kinematic regions: Q 2 < 1(GeV/c) 2 (low Q 2 )andQ 2 > 1(GeV/c) 2 (high Q 2 ) regions. The present work is mainly focused on the analysis for high Q 2 . However, the analysis for the low Q 2 region is summarised in sec. 6. For completeness, the slides of the presentation can be found in [4]. 351
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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
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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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Page 306 and 307: 4 Results of GEp-III Experiment In
Page 308 and 309: 6 Theoretical Developments The earl
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Page 312 and 313: models have recently been challenge
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Page 320 and 321: In summary, we made measurements on
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Page 324 and 325: The sensitivity of the data to the
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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
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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 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
Page 370 and 371: not even resemble the data behavior
Page 372 and 373: to the slope of the Rosenbluth plot
Page 374 and 375: The differential cross section of t
Page 376 and 377: with zero for all mass ranges, with
Page 378 and 379: more precise and dedicated measurem
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Page 382 and 383: is recorded, a good particle identi
Page 384 and 385: error of the extracted asymmetries
Page 386 and 387: 2.6 Summary and Outlook The first d
Page 388 and 389: 386
Page 391 and 392: PROTON BEAM POLARIZATION MEASUREMEN
Page 393: N A 0.06 0.05 0.04 0.03 0.02 0.01 0
Page 396 and 397: Intensity profile (arb. units) 1 0.
Page 398 and 399: [4] H. Okada et al., Proc. of the 1
Page 400 and 401: 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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