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

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

Contents

• Introduction

• Brief description for PACIAE

• Results

• Conclusion

Introduction

Sketch of lowest order (Born approximation) e-p deep inelastic scattering (DIS)

q2 = -Q2 q2 = -Q2

hh

NC CC

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

• 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

s

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

Second order e-p DIS Feynman diagram

Complete e-p NC differentia cross section may be factorized as

2 2

2 2= 1+ )(1 )

BornQED weakd d

dxdQ dxdQ

（

: QED radiative correction : weak radiative correction (similar for CC)

2 222

12 2

4 ( )[ (1 ) ( ) ]

2

Bornd F x Mxyy F x y

dxdQ Q x E

QEDweak

Two independent variables: in the past: (E', ) presently: (xB ,Q2); or (xB ,W2); or (xB ,y)

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

for the normalized hadron yield as a function of z

Polar angle

Brief description for PACIAE

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): px=py=0, pz=pbeam Target nucleons (in Lab, frame) px=py=pz=0 Decompose nucleus-nucleus colli. -> NN collisions according to straight-line trajectories & NN total x-section

PYTHIA 6.4 vs. PACIAE2.0

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

qq q

2) Parton rescattering (PRS)

• PRS is performed by MC method

• 2->2 LO perturbative QCD x-section is used

3) Hadronization

Two options are provied for hadronization

• Lund string fragmentation

• Phenomenological coalescence model

4) Hadron rescattering (HRS)

Usual two body collision model is used Only some hadrons are considered

& their anti-particles

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

Results

1. Comparison with data and other theories

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, pT, & \eta

LOQCD:

in factorization theorem framework: PDF, hard scattering x-section, & FF

in quark parton model: hadron yield is a convolution of PDF & FF

2. Effect of α and β

3. Effect of PRS & HRS

4. Effect of SQSF

Conclusions

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

Thank you very much

selected in order of Eqs. 2,1,3,4,5,6,7,& 8

hadron,(Eh,pl,pt)

direction of virtual photon

taken from Nucl. Phys. B780(2007)1

z > 0.1>4 GeV

III) HERMES results: 27.6 GeV e- beam on A

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

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

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

Plan for studying A dependence of ratio

• Comparing with HERMES data• Predecte for LHeC (60 or 140 e- beam energy) • Utilize <z>, <Q2>, … (cf. NP,B780(2007)1) & same experimental constraints (Lorentz invarience)

e(K’,E’ )

p(p)

h

e(K,E)

…

first

(born) second

+ +

Sketch of ep deep inelastic scattering

EM

EM

EM

EM

EM EMX

/

)( 2'22

'

hEz

kkqQ

EE

X

h

;… *

black box,hints for QCD processes: vacumeexcitation,parton shower,resattering,etc.

q=-Q2

(q, )

A sketch for an exposing of black box

struck quark

fragments

Exchange Z,W+,and W-,bosons either