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Comparative study of the specific charge hadron in electron SIDIS off proton and deuteron Ben-Hao Sa China Institute of Atomic Energy Central China normal University
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It was done in collaboration with CCNU: Dai-Mei Zhou Yun Cheng Xu Cai CIAE: Yu-Ling Yan Xing-Long Li Xiao-Mei Li Bao-Guo Dong benefit
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Contents Introduction Brief description for PACIAE Results Conclusion
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Introduction
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Sketch of lowest order (Born approximation) e-p deep inelastic scattering (DIS) q 2 = -Q 2 hh NC CC
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IDIS (inclusive deep inelastic scattering) in which all accessible states X & h, all possible outgoing momenta, are included. Remainder is only the scattered electron SIDIS (semi-inclusive deep inelastic scattering) is the same as DIS but includes a specific type of hadron in addition
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Confinement of quark and gluon in hadron, such as PDF, FF, & extractions, as well as searching for Higgs boson, SUSY, etc. Hadronization processes space & time evolutions, energy loss, etc. eRHIC (e-p,CM energy 45 – 175 GeV), LHeC (e-p, CM energy more than 1 TeV), and EIC We, extend PACIAE for l-p and l-A, Confront IDIS: an impotent & hot frontier in between particle & nuclear physics since eightieth of last century. It plays a crucial role in the field of nDIS era
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Second order e-p DIS Feynman diagram
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Complete e-p NC differentia cross section may be factorized as : QED radiative correction : weak radiative correction (similar for CC)
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Two independent variables: in the past: (E', ) presently: (x B,Q 2 ); or (x B,W 2 ); or (x B,y)
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HERMES e - SIDIS off p & D experiments HERRMES -> specific charged hadron yield of pi +,pi -,K +,K - in DIS is crucial for reliable extraction of FF with distinguished from HERMES corrects measured yield of type h hadrons for: limitation in geometric acceptance radiative effect detector resolution Born-level yield is then resulted. Normalizing it by DIS yield (yield of scattered e - ) they obtain
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for the normalized hadron yield as a function of z Polar angle
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Brief description for PACIAE
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1) Initiation Nucleons in colliding nucleus, distributed according to Woods-Saxon distribution Paticipant nucleons, to be inside OZ Spectator nucleons, to be outside OZ but inside nucleus system Projectile nucleons (in Lab. frame): p x =p y =0, p z =p beam Target nucleons (in Lab, frame) p x =p y =p z =0 Decompose nucleus-nucleus colli. -> NN collisions according to straight-line trajectories & NN total x-section PYTHIA 6.4 vs. PACIAE2.0
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Describe each NN collision by PYTHIA with string fragmentation switched-off & qq ( ) broken into q pair ( pair) A partonic initial state is obtained after all NN collisions are exhausted
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2) Parton rescattering (PRS) PRS is performed by MC method 2->2 LO perturbative QCD x-section is used
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3) Hadronization Two options are provied for hadronization Lund string fragmentation Phenomenological coalescence model
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4) Hadron rescattering (HRS) Usual two body collision model is used Only some hadrons are considered & their anti-particles
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Some specials For p+p & p+A (A+p), OZ is not introduced l+p & l+A are dealt like p+p & p+A,respectively As l+p x-section is a few order of magnitude lower than p+p, incident lepton is probably only one colliding with nucleon when it passes through the target Strike nucleon is the one with lowest approaching distance from incident lepton
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Results
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1. Comparison with data and other theories
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HLMC: composed of Lepto e-p event generator <- JETSET 7.4 & PYTHIA 5.7 Program for detector simulation Event reconstruction where thirteen parameters were tuned to the yield as function of z, p T, & \eta LOQCD: in factorization theorem framework: PDF, hard scattering x-section, & FF
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in quark parton model: hadron yield is a convolution of PDF & FF
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2. Effect of α and β
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3. Effect of PRS & HRS
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4. Effect of SQSF
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Conclusions
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Default PACIAE reproduced HERMES data nearly as well as HLMC where thirteen paramters were tuned Normalized yield increases (decreases) with increasing α and β Effect of PRS & HPS is visual, former>later, due to interacting volume & # of particles Effect of SQSF is obvious. It is possible to improve the agreement between HERMES & PACIAE by adjusting SQSF Effects are expected to be increased with increasing target size
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Thank you very much
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selected in order of Eqs. 2,1,3,4,5,6,7,& 8 hadron,(E h,p l,p t ) direction of virtual photon
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taken from Nucl. Phys. B780(2007)1 z > 0.1 >4 GeV III) HERMES results: 27.6 GeV e - beam on A
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Theoretical models 1) Phenomenological models: Formation time/legth Absorption cross section NP, B291(1987)793; NP, B346(1990)1; Z. Phys. C56(1992)493; Eur. Phys. J. C44 (2005)219; hep-ph/0205123 arXiV:1310.5285
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2) QCD-inspired models: Partonic rescattering (energy loss) NP, B483(1997)291; NP, B484(1997)265; PRL 85(2000)3591; PRL 89(2002)162301; JHEP 0211(2002)44; NP, A720(2003)131; Eur. Phys. J. C30(2003)213; arXiV:09073534; NP, A761(2005)67; PR, C81(2010)024902 3) PYTHIA + BUU simulation Formation time/length Hadronic rescattering PR, C70(2004)054609; NP, A801(2008)68
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4) PACIAE Partonic initiation for eA collisions Praton rescattering hadronization hadron rescatering As both partonic and hadronic rescatterings are considered in PACIAE, experimental results may be better studied by PACIAE
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Plan for studying A dependence of ratio Comparing with HERMES data Predecte for LHeC (60 or 140 e - beam energy) Utilize,, … (cf. NP,B780(2007)1) & same experimental constraints (Lorentz invarience)
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e(K’, E’ ) p(p) h e(K,E) … first (born) second ++ Sketch of ep deep inelastic scattering X X h ;… * black box,hints for QCD processes: vacume excitation,parton shower, resattering,etc. q=-Q 2 (q, )
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A sketch for an exposing of black box struck quark fragments Exchange Z,W +,and W -,bosons either
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