The asymmetries of semi-inclusive deep inelastic scattering of neutrino on polarized deuteron with the neutral current have been used for the extraction of valence quark, anti­-quark and strange quark contributions to the nucleon spin

Degtyareva, E. A.

Timoshin, S. I.

Electronic Library Pavel Sukhoi State Technical University of Gomel (GSTU)

Nonlinear Dynamics and Applications. Vol. 15 (2008) 40 - 43The Spin Structure of the Nucleon from Semi-Inclusive Deep Inelastic Neutrino Scattering with Neutral CurrentE.A.Degtyareva, S.I.Timoshin* Gomel State Technical "University, 246146 Gomel.. BelarusThe asymmetries of semi-inchisivc deep inelastic scattering of neutrino on polarized deuteron with the neutral current have been used for the extraction of valence quark, anti­quark and strange quark contributions to the nucleon spin.PACS numbers: I3.15.+g, 12.39.-х, 14.65.-qKeywords: nucleon spin, quark, deep inelastic scattering, neutrino processes1. IntroductionThe investigation of spin structure of the nucleon is one of the actual problems of particle physics, The present experiments [1] show, that total quark contribution to the nucleon spin is 0.30-0.35, th« strange quark polarization is negative and have matter -8-10%. At the same time data of HERMES shows, that, it can be close to zero. Existing experimental data specify, that gluon polarization has not big positive value as it earlier supposed. The orbital angular momentum of quarks and gluons contribution to the nucleon spin while experimental data are not present.In the last years the information of the quarks and gluons contribution to the spin of nucleon receivt from semi-inclusive experiments. However the semi-inclusive deep inelastic scattering (S1DIS) witl charged leptons [2] allow to receive the valence quarks contribution. At the same time is important to know strange quarks contribution for the nucleon spin problem decision. The neutrino processes are the interest from this point, of view. In article [4] the spin structure of the nucleon in i/(P)Ar- DIS with the charged weak current was considered.In the present work the approach [4] on the neutrino deep inelastic scattering with a neutral currea extends.2. The semi-inclusive P^ A ’-DIS with neutral currentThe differential cross sections of the semi-inclusive i/(p)Ar-DIS with the neutral weak current ц the quark-parton model arc equal to the Ji _ f ~a  \h 1wheredxdydz« V  = 1 ъчу  ̂ * 52 ~ ■“ <! ' 4'E -m a ik  d e k a te r in a a S iD a il .ru10The spin structure of the nucleon from semi-inclusive deep inelastic . ..=  < ^ .p ; 4 E  +b<ly + } ^ ) D ' ‘(z) ± £  -  b4 y f ] S y ( . ^L Q X /  q \  /  JНете— (9v T 9Afq- bq — (уУУЛИр (sv)u = 2 -  =»пгви , (UA)U = M l ,  -  I  I |em4„, M d,, = Ц ,a o  = C ^M E /v , x  = у = г =  =  “ V2 , Ч = к -  к', Е  is the energy of incomingneutrino or antineutrino, k(k ). P. Ph - are the initial (final)lepton, the nucleon and hadron h four ^omenta respectively , G is Fermi constant. M is the nucleon mass, j/i =  1 -  y, PN  is degree longitudinal polarization of nucleon: q(x), &q(x)(q(x), A^(r)) is the unpolarizcd (polarized) quark (antiquark) function of contribution, Z)J(z) is the function fragmentation of quark q to the hadron h.Define the polarization asymmetries in the form ofНт.П +(3)The first arrow corresponds to the helicity of the neutrino ( 1 ) or antineutrino ( f  ), and the second .  to the spin direction of the nucleon: { — +1) and I (Py  =  -1 ).Set cross sections (1) in (3) received(4)where(5)Consider the deuteron target. In this case the cross sections are equal to the expressionswhere ш =  0.05 is a probability of D-statc of the wave1 function of the deuteron.Then from (2), (4). (5), (6) and consider the equation for the тг-meson function of fragmentatk+  —  _  П Л  ’ r jT T 1 7Г _ _ Г ) 7 Г + - Я ”for the semi-inclusive pd-DIS asymmetries can be obtained as followsД..Т+-Я- _ _  i 5 ^' "rf ” y :Q ^ )  + y t ^ i v ^ ' )  'where N  = ^ s m 20w , Q(x) = utx) + «(ж) + d(x) + d(x), qv(x) = uy(x) + dy(x).Similarly by asymmetries for semi-inclusive antineutrino DIS on polarized deuterons we receiyfprf y t^ Q iz )  + y^qvix)The obtained asymmetries not depend on the function of fragmentation.Asymmetries (7), (8) соц the function of distribution of the polarized quarks Д</(г) and antiquarks Aq(x). The first pat distribution moments as followsAq(Aq) = У Aq{x)(Aq(x))d:which correspond to the quark q (antiquark q) contribution to the spin of nucleon.Therefore from observable asymmetries (7). (8) the quark contributions to the nucleon spin car defined asAny 4- Ady =} N y, Vi Qis') + y f  Ngv(x) n -  У  y+NQ(x) + У1 qv (ж) */-- t---------- ------- L —— --- J---- dx.0 (1 -  1.5w) ( 2Л У  У, + (A y )2 + (У )2 )Au 4- Ad =}. О У  + У )  У < Ж  + Уі Ы О У м  71 -  №  ~УІ N 1 W W 'W  + Ji Q(x) A^d 71/  ----------------L----------------------- 1 1 ---------------------------------------- І0 2(1 -  1.5У 2ЛГУ УГ + (N y ;)2 + (У ) 2The strange quark contribution can be determinate using the additional measured quantity- axial charge agag = (Atg- + Ady) + 2(Ди + Ad) — 2(As + As).Then .using (9), (10), (11) the strange quark contributions isАй + Ad42The >pin structure of the nucleon from semi-inclusive deep inelastic . . .3. C onclusionP polarizing asymmetries * of ufy}- DIS with neutral current on the deuteron targets was received independent of functions of fragmentation.2. Trie valence quark (A uy + Adv у antiquarks (Дй -V Ad) contribution to  the nucleon spin is obtained from measurable asymmetries . Using of the additional measurable quantity allowsto receive information about strange quarks contribution (As- P As).References[j] The HERMES Collaboration. ArXiv: hep-ex /' 0609039.[2] Altarelli G. Status of the Standard Model at the LHC Start. ArXiv: hep-ph /  0804.4147.[3] The polarised valence quark distribution front serni-inclusive DIS. The COMPASS Collaboration. ArXiv: hep-ex /  0707.4077.|4] Degtyareva E.A.,Timoshin S.I.//Proc, of the national Academy ol Sciences of Belarus. Ser. of Phys- Math.sciences. - 2008. no. 1.- p.74-79.[5] Christova E.. leader E. A model independent approach to semi-inclusive deep inelastic scattering. arXiv: he p-pli / 0412150.43

The Spin Structure of the Nucleon from Semi-Inclusive Deep Inelastic Neutrino Scattering with Neutral Current

https://elib.gstu.by/bitstream/220612/28040/1/40-43.pdf

The Spin Structure of the Nucleon from Semi-Inclusive Deep Inelastic Neutrino Scattering with Neutral Current

Abstract

Similar works

Full text

Available Versions

Electronic Library Pavel Sukhoi State Technical University of Gomel (GSTU)