Bound state effects in transverse momentum parton distributions

Diakonos, F. K.; Galanopoulos, Georgios; Maintas, X. N.

doi:10.1103/physrevd.73.034007

Cited by 3 publications

(8 citation statements)

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“…Such potentials have been extensively used for a consistent description of a large set of hadronic observables which besides their spectra include the photo-couplings [12], the electromagnetic form factors and the strong decay ampli-tudes [13,14]. Recently it has been proposed that within the potential model approach one could also obtain an estimation of the transverse momentum distribution of partons inside the hadrons g(k T ) [15]. The resulting probability density, characterized by a non-Gaussian shape, was then used within the framework of perturbative QCD for a phenomenological description of the cross section for π 0 production in pp collisions.…”

Section: Introductionmentioning

confidence: 99%

“…Interestingly enough, this treatment turned out to be very efficient in the description of the experimental data resolving several unsatisfactory issues present in the usual approach involving a Gaussian form for g(k T ). In [15] the treatment was based on a twobody potential of the form (1) while in a later work the MIT bag model [16] was used in a similar manner to obtain g(k T ) and subsequently to describe successfully the prompt photon production in pp collisions [17]. The results of these two works indicate that confinement, asymptotic freedom and/or relativistic description make an imprint on the intrinsic transverse momentum distribution of the constituent quarks, detectable in the cross section of pp collisions.…”

Section: Introductionmentioning

confidence: 99%

“…Having fixed A k , B k we determine g(k T ) for several values of k (k = 0.1, 0.5, 1, 2) and then we use the standard treatment within perturbative QCD for the calculation of the cross section for prompt photon production in a pp collision experiment. We compare our results with those of [15,17] in order to extract information concerning the presence or not of traces of three-body effects in g(k T ) traceable through the considered experimental data.…”

Section: Introductionmentioning

confidence: 99%

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Partonic transverse momenta in non-relativistic hyper-central quark potential models

Diakonos,

Kaplis,

Maintas

2010

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We investigate the impact of three-body forces on the transverse momentum distribution of partons inside the proton. This is achieved by considering the three body problem in a class of hypercentral quark potential models. Solving the corresponding Schrödinger equation we determine the quark wave function in the proton and with appropriate transformations and projections we find the transverse momentum distribution of a single quark. In each case the parameters of the quark potentials are adjusted in order to sufficiently describe observable properties of the proton. Using a factorization ansatz we incorporate the obtained transverse momentum distribution in a perturbative QCD scheme for the calculation of the cross section for prompt photon production in pp collisions. A large set of experimental data is fitted using as a single free parameter the mean partonic transverse momentum. The dependence of kT on the collision characteristics (initial energy and transverse momentum of the final photon) is much smoother when compared with similar results found in the literature using a Gaussian distribution for the partonic transverse momenta. Within the considered class of hyper-central quark potentials the one with the weaker dependence on the hyper-radius is preferred for the description of the data since it leads to the smoothest mean partonic transverse momentum profile. We have repeated all the calculations using a two-body potential of the same form as the optimal (within the considered class) hyper-central potential in order to check if the presence of three body forces is supported by the experimental data. Our analysis indicates that three-body forces influence significantly the form of the parton transverse momentum distribution and consequently lead to an improved description of the considered data.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Partonic transverse momenta in non-relativistic hyper-central quark potential models

Diakonos,

Kaplis,

Maintas

2010

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“…Within the framework of pQCD an alternative scenario for the description of pp collisions has been recently proposed [26], incorporating the calculation of the partonic transverse momentum distribution using a phenomenological quark potential model introduced in the past to describe baryonic spectra [27,28]. The underlying idea in this treatment is to determine the influence of bound state effects on the shape of g(k T ).…”

mentioning

confidence: 99%

“…The underlying idea in this treatment is to determine the influence of bound state effects on the shape of g(k T ). In the calculation performed in [26] g(k T ) turns out to have a non-gaussian profile with a characteristic tail. Furthermore, when applied to the description of the pp → π 0 + X process, one succeeds to overcome the disadvantages of the gaussian g(k T ) discussed above.…”

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confidence: 99%

MIT bag model inspired partonic transverse momentum distribution for prompt photon production inppcollisions

2008

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We consider the prompt photon production in pp collisions using, within the framework of perturbative QCD, a non-gaussian distribution for the transverse momentum distribution of the partons inside the proton. Our description adopts the widely used in the literature factorization of the partonic momentum distribution into longitudinal and transverse components. It is argued that the non-gaussian distribution of the intrinsic transverse momenta of the partons is dictated by the asymptotic freedom as well as the 3D confinement of the partons in the proton. To make this association more transparent we use the MIT bag model, which plainly incorporates both properties (asymptotic freedom, confinement), in order to determine in a simplified way the partonic transverse momentum distribution. A large set of data from 6 different experiments have been fitted with this simple description using as a single free parameter the mean partonic transverse momentum kT . Surprisingly enough, a perfect fit of the experimental data turns out to require kT values which are compatible with Heisenberg's uncertainty relation for the proton and decrease almost smoothly as a function of the scaled variable z = p T √ s , where pT is the transverse momentum of the final photon and √ s is the beam energy in the center of mass frame. Our analysis indicates that asymptotic freedom and 3D confinement may influence significantly the form of the partonic transverse momentum distribution leaving an imprint on the pp → γ + X cross section.PACS numbers: 13.60. Le,13.85.Ni,12.38.Qk The production of photons with large transverse momentum is an excellent probe of the dynamics in hard scattering processes [1,2]. In particular, the study of direct photon production possesses numerous and well known advantages, both theoretical and experimental [2][3][4][5][6][7][8][9]. In the latter case the main advantage is that photons are easier to detect than jets. From the theoretical point of view the main advantage is the simplicity of the process allowing for an accurate determination of the gluon distribution within the proton. In the lowest order (O(αα s )) only two subprocesses, gq → γq (Compton) and qq → γg (annihilation), contribute to high p T photons. Their characteristic signature is the production of a photon isolated from the hadrons in the event, accompanied by a kinematically balancing high-p T jet appearing on the opposite site. In the next-to-leading order (NLO) the process associated with the production of a photon coming from the collinear fragmentation of a hard parton produced in a short-distance subprocess, constitutes a background to the direct photon production of the same order in α s as the corresponding Born level terms [10] provided that the fragmentation scale is large enough. However, the contribution from fragmentation remains small (less than 10%) for fixed target experiments and becomes significant only in inclusive prompt photon production at higher collider energies [10]. Recently there has been observed a systematic disagreeme...

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Partonic transverse momenta in non-relativistic hyper-central quark potential models

2009

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Bound state effects in transverse momentum parton distributions

Cited by 3 publications

References 46 publications

Partonic transverse momenta in non-relativistic hyper-central quark potential models

Partonic transverse momenta in non-relativistic hyper-central quark potential models

MIT bag model inspired partonic transverse momentum distribution for prompt photon production inppcollisions

Partonic transverse momenta in non-relativistic hyper-central quark potential models

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