High Density QCD

Ducati, M. B. Gay

doi:10.1590/s0103-97332001000200002

Cited by 7 publications

(10 citation statements)

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“…For the correspondent wavefunctions, the quark mass in Eqs. (2,3) should be substituted by the charm quark mass m c . Here, we should take care of the connection between the Regge parameter x = (W 2 + Q 2 )/(Q 2 + 4 m 2 q ) and the Bjorken variable x Bj .…”

Section: B the Longitudinal Structure Function Fl(x Q 2 )mentioning

confidence: 99%

Unitarity corrections to the structure functions through the dipole picture

Machado¹

2002

Phys. Rev. D

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We study the dipole picture for the description of deep inelastic scattering, focusing on the structure functions which are driven directly by the gluon distribution. One performs estimates using the effective dipole cross section given by the Glauber-Mueller approach in QCD, which encodes the corrections due to the unitarity effects associated with the saturation phenomenon. We also address issues about frame invariance of the calculations when analyzing the observables.

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Section: B the Longitudinal Structure Function Fl(x Q 2 )mentioning

confidence: 99%

Unitarity corrections to the structure functions through the dipole picture

Machado¹

2002

Phys. Rev. D

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“…Such a region presents the onset of the saturation phenomenon (at scale Q 2 s ), i.e. the taming of the parton (mostly gluon) distribution due to nonlinear dynamics associated with unitarity effects 1 . In this contribution, we study the high energy DY cross section in the target rest frame.…”

mentioning

confidence: 99%

Parton Saturation Effects to the Drell-Yan Process in the Color Dipole Picture

Betemps¹,

Machado²

2003

Hadron Physics 2002

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We report on the results obtained in the study of the parton saturation effects, taken into account through the multiscattering Glauber-Mueller approach, applied to the Drell-Yan (DY) process described in the color dipole picture. As a main result, one shows that those effects play an important role in the estimates of the DY differential cross section at RHIC energies.The Drell-Yan (DY) process, i.e. the production of massive lepton pairs in hadronic collisions, in conjunction with deep inelastic scattering (DIS), has been one of the important processes probing strong interaction physics. Recently, in connection with the availability of high energy accelerators, a great attention has been focused on the small-x region of QCD. There, the parton densities become high and the limits of the perturbative methods are tested. Such a region presents the onset of the saturation phenomenon (at scale Q 2 s ), i.e. the taming of the parton (mostly gluon) distribution due to nonlinear dynamics associated with unitarity effects 1 . In this contribution, we study the high energy DY cross section in the target rest frame. In this case, the relevant degrees of freedom are the projectile wavefunction and the dipole-proton effective cross section. The underlying process is the scattering of a parton from the projectile structure function off the target color field. This parton radiates (bremsstrahlung) a massive photon, which subsequently decays into a lepton pair. The interaction with the target can occur before or after the photon emission. A remarkable feature emerging is that the γ * q-proton (or hadron) interaction can be described by the same qq (color dipole)-proton cross section as in DIS. Although diagramatically no dipole is present, the interference among graphs results in a product of two quark amplitudes in the DY cross section testing the external gluonic field at two different transverse positions (impact parameters), in a similar way to DIS 2 . In such a representation, the photoabsorbtion cross section on deep inelastic is described by the convolution of the wavefunctions, Ψ γ * , from the virtual photon and the interaction dipole cross section, σ dip . The wavefunctions are considered taking into account the simplest photon Fock state configuration,

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“…In that follows we present a brief review of some signatures of the high parton density regime (For other recent reviews see Refs. [12,13,14]). In the next section, we discuss the high density effects in the deep inelastic scattering process and the property of geometric scaling predicted theoretically and observed in the HERA data.…”

Section: )] and On The Atomic Number Of The Colliding Nuclei [Rmentioning

confidence: 99%