References - Bogoliubov Laboratory of Theoretical Physics - JINR

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1.3 Flavor Decomposition of the Helicity Structure If we want to understand the three-dimensional structure of the nucleon, we have to go beyond inclusive measurements that are only sensitive to the longitudinal momentum fraction x carried by the quarks. The large acceptance of CLAS allows us to collect data on semi-inclusive (SIDIS) reactions simultaneously. In these reactions, a second particle, typically a meson, is detected along with the scattered lepton. By making use of the additional information given by the identification of this meson, one can learn more about the polarized partons inside the nucleon than from DIS alone. The asymmetry measured by DIS experiments is sensitive to combinations of quark and anti-quark polarized parton distribution functions (Δq+Δ¯q), as well as (via NLO analysis) the gluon PDF ΔG. SIDIS experiments exploit the statistical correlation between the flavor of the struck quark and the type of hadron produced to extract information on quark and antiquark PDFs of all flavors separately. Combined NLO analysis of DIS and SIDIS data can therefore give a more detailed picture of the contribution of all quark flavors and both valence and sea quarks to the total nucleon helicity. Beyond the determination of the polarized PDFs, SIDIS data can also yield a plethora of new insights into the internal structure of the nucleon as well as the dynamics of quark fragmentation. For instance, looking at the z- andpT -dependence of the various meson asymmetries (both double spin asymmetries and single spin target or beam asymmetries), one can learn about the intrinsic transverse momentum of quarks and their orbital angular momentum. 2 Measurements and Data Analysis A1 and g1 were extracted from measurements of the double spin asymmetry A� in inclusive ep scattering: g1 = F1 1+γ2 [A�/D +(γ − η)A2], (4) where F1 is the unpolarized structure function, A2 is the virtual photon asymmetry, and γ, D and η are kinematic factors. F1 and A2 are calculated using a parametrization of the world data, and A� is measured. The spin asymmetry for ep scattering is given by: A� = N− − N+ N− + N+ CN fPbPtfRC + ARC, (5) where N−(N+) is the number of scattered electrons normalized to the incident charge with negative (positive) beam helicity, f is the dilution factor needed to correct for the electrons scattering off the unpolarized background, fRC and ARC correct for radiative effects, and CN is the correction factor associated with polarized 15 N nuclei in the target. A� was measured by scattering polarized electrons off polarized nucleons using a cryogenic solid polarized target and CLAS in Hall B. The raw asymmetries were corrected for the beam charge asymmetry, the dilution factor and radiative effects. Since the elastic peak is within the acceptance range, the product of beam and target polarization was determined from the known ep elastic asymmetry. The longitudinally polarized electrons were produced by a strained GaAs electron source with a typical beam polarization of ∼ 70%. Two solid polarized targets were used: 294
15 ND3 for polarized deuterons and 15 NH3 for polarized protons. The targets were polarized using the method of Dynamic Nuclear Polarization, with the typical polarization of 70-90% for protons, and 10-35% for deuterons. Besides the polarized targets, three unpolarized targets ( 12 C, 15 N, liquid 4 He) were used for background measurements. The scattered electrons were identified using the CLAS package [4], consisting of drift chambers, Cherenkov detector, time-of-flight counters and electromagnetic calorimeters. Data were taken with beam energies of 1.6, 2.4, 4.2 and 5.7 GeV, covering a kinematic range of of 0.05
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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
Page 246 and 247: SEMI-INCLUSIVE DIS AND TRANSVERSE M
Page 248 and 249: The yellow band in Fig. 1 is the re
Page 250 and 251: At leading twist, a third asymmetry
Page 252 and 253: THE COMPLETION OF SINGLE-SPIN ASYMM
Page 254 and 255: A N , % 30 20 10 0 0 0.2 0.4 0.6 0.
Page 256 and 257: Unexpectedly large single spin asym
Page 258 and 259: THE GENERALIZED PARTON DISTRIBUTION
Page 260 and 261: , E) H ~ (H, I Im C 5 4 3 2 1 Q = 1
Page 262 and 263: Reducing to a common denominator (
Page 264 and 265: LAMBDA PHYSICS AT HERMES S. Belosto
Page 266 and 267: analysis was carried out reconstruc
Page 268 and 269: 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 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
Page 318 and 319: is constant with cos θ∗ , as exp
Page 320 and 321: In summary, we made measurements on
Page 322 and 323: angle between the direction of the
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
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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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