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{\Large \bf Accessing characteristics of hadronization from DIS } 
\\[.5cm]

Valeria Muccifora\\[.2cm]
{\small \em 
Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, via E.Fermi, Frascati, Italy}
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A review on the recent progress in the study of the parton propagation, interaction and hadronization in 
{\it cold} nuclear matter has been presented.
It has been pointed out that the cleanest environment to address nuclear modification of hadron production is the nuclear Deep Inelastic Scattering:
it allows to experimentally control many kinematic variables; the nuclear medium (i.e., the nucleus itself) is well known; the hadron multiplicity in the final state is low, allowing for precise measurements. Moreover, the nucleons act as fentometer-scale detectors of the hadronizing quark, allowing to study its
space-time evolution into the observed hadron.

\vspace{.2cm}

 The experimental highlights from deep inelastic lepton nuclear scattering have been shown,
in particular results from the HERMES experiment have been discussed.
At Hermes, nuclear semi-inclusive deep-inelastic scattering 
is used to study the quark propagation and hadronization  
via single hadron multiplicity ratio  \cite{hermess}, double hadron production \cite{hermesd}
and broadening of the hadron transverse momentum $p_t~$\cite{ptbroad}.
 While hadron multiplicity ratio is sensitive to all stages of the 
hadronization process, i.e. to the production time $t_p$ of the colorless q$\bar{q}$ system and to the formation time $t_f$ of the final hadron,
 the $p_t$-broadening has been shown to be sensitive to  $t_p$ 
because, once the q$\bar{q}$ is formed (t $>$ $t_p$) , no further broadening occurs as 
inelastic interaction is suppressed. 

\vspace{.2cm}
The most recent theoretical frameworks for describing the interaction of energetic partons and space-time evolution of the hadronization process in nuclear DIS have been discussed.
In particular models based on parton energy loss effect mainly \cite{wang,arleo} have been compared with models based mainly on the  interaction of the  q$\bar{q}$ system in the medium and that are sensitive to the time evolution of the hadronization in the medium \cite{kopel}-\cite{gellmeister}. 

\vspace{.2cm}

It has been pointed out the importance to study parton propagation and interaction in {\it cold} nuclear matter for the interpretation
of data in A+A collisions. In particular the connections between the kinematic in DIS and in nucleon-nucleon collisions have been discussed and 
the equivalent phase spaces covered by different experiments have been compared \cite{acca2}.

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\begin{thebibliography}{9}

\bibitem{hermess} A. Airapetian {\it et al.}, Hermes Collab., {\it Eur. Phys. J.} C {\bf 20} (2001) 479;
 {\it Phys. Lett.} B {\bf 577} (2003) 37;  {\it Nucl. Phys.} B {\bf 780} (2007) 1
\bibitem{hermesd} A. Airapetian {\it et al.}, Hermes Collab., {\it Phys. Rev. Lett.} {\bf 96} (2006) 16230.
\bibitem{ptbroad} Y. Van Haarlem, A. Jgoun, P. Di Nezza, arXiv:0704.3712

\bibitem{wang} X.N. Wang and X. Guo, {\it Nucl. Phys.} A {\bf 696} (2001) 788
\bibitem{arleo} F. Arleo, JHEP {\bf 0211} (2002) 044, Eur. Phys. J P {\bf C30} (2003) 213. 
\bibitem{kopel} B.Z. Kopeliovic, J. Nemchik, E. Predazzi and A. Hayashigaki, {\it Nucl. Phys.} A {\bf 740} (2003) 211
\bibitem{falter} T. Falter {\it et al.}, {\it Nucl. Phys.} B {\bf 594} (2004) 61
\bibitem{acca} A. Accardi, D. Gr\"{u}newald, V. Muccifora, H.J. Pirner, {\it Nucl. Phys.} A {\bf 761} (2005) 67
\bibitem{pirner} H.J.Pirner and D. Gr\"{u}newald, hep-ph/0608033
\bibitem{gellmeister} K.Gellmeister {\it et al.} nucl-th/0701064;nucl-th/07122200.
\bibitem{acca2} A. Accardi arXiv:0706.3227 [nucl-th].
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