Heavy quark production in parton model and in QCD

Ryskin, M.G.; Shabelski, Yu. M.; Shuvaev, A. G.

doi:10.1007/s002880050027

Cited by 30 publications

(29 citation statements)

References 5 publications

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“…2x x g 3 5x). This conclusion also agrees with that of Ryskin et al [21] where the estimated value of the longitudinal gluon momentum x g is shown to be approximately three times larger than the Bjorken x B , that corresponds to the expansion at α 0 75.…”

Section: Resultssupporting

confidence: 92%

A solution of the DGLAP equation for gluon at low x

Choudhury

Sahariah

2002

Pramana - J Phys

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We obtain a solution of the DGLAP equation for the gluon at low x first by expanding the gluon in a Taylor series and then using the method of characteristics. We test its validity by comparing it with that of Glück, Reya and Vogt. The convergence criteria of the approximation used are also discussed. We also calculate ∂ F 2´x Q 2 µ ∂ ln Q 2 using its approximate relations with the gluon distribution at low x. The predictions are then compared with the HERA data.

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Section: Resultssupporting

confidence: 92%

A solution of the DGLAP equation for gluon at low x

Choudhury

Sahariah

2002

Pramana - J Phys

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“…As a result, S(0, 0) produces the standard expression of collinear factorization (ref. [10,14]), while S(q 1⊥ , 0), S(0, q 2⊥ ) correspond to the asymmetric configurations, where one of the gluons is described by the unintegrated distribution and the other by the integrated one. Here it is important to notice that when we insert (5), (6) GeV from [15] In all our numerical calculations we used for the unintegrated gluon distribution F (x, k) the code by Kwiecinski, Martin and Staśto [10], because they use a combination of DGLAP and BFKL equations which governs simultaneously the evolution in Q 2 and x.…”

Section: Fig 2 the Effective Vertexmentioning

confidence: 99%

Heavy-quark production as a sensitive test for an improved description of high-energy hadron collisions

et al. 2000

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QCD dynamics at small quark and gluon momentum fractions or large total energy, which plays a major role for HERA, the Tevatron, RHIC and LHC physics, is still poorly understood. For one of the simplest processes, namely bb production, next-to-leading-order perturbation theory fails. We show that the combination of two recently developed theoretical concepts, the k ⊥ -factorization and the next-to-leadinglogarithmic-approximation BFKL vertex, gives perfect agreement with data. One can therefore hope that these concepts provide a valuable foundation for the description of other high energy processes.Existing QCD calculations describe many high energy observables which involve partonic transverse momentum rather poorly. This is also true for the theoretically especially clean case of bb production, which was investigated experimentally at Fermilab [1]. Since central quark-antiquark production at √ s = 1.8 TeV is sensitive to very small gluon momentum fraction x ≈ 10 −2 − 10 −4 , one probes the gluon content of the nucleon at small x, which is a central issue of current research. We reconsider this process and combine as essential new ingredients the k t -factorization scheme with the next-to-leadinglogarithmic-approximation (NLLA) BFKL production vertex derived in [2]. The k t -factorization approach for the description of high energy processes [3-6] differs strongly from the conventional NLO collinear approximation (e.g. [7]) because it takes the non-vanishing transverse momenta of the scattering partons into account. The usual gluon densities are replaced by unintegrated gluon distributions which depend on the transverse momentum k t . These together with the k t -factorization form a basis for a general calculation scheme for high energy (i.e. small x). The standard collinear approximation has the advantage of being closely related to the operator product expansion. It is, however, only justified for the processes dominated by x = O(1). In application to processes governed by small x the k t -factorization approach has the advantage that its approximations correspond to the dominant kinematics. Essential small x contributions are included in the Born approximation which in the collinear approach are accounted for in higher orders only. This is well known from the case of structure functions where the DGLAP evolution is appropriate for x = O(1) and the BFKL evolution for small x.While the k t -factorization formalism is very attractive theoretically, its phenomenological usefullness has been mostly tested in the case of the structure function F 2 [9,10]. The NLLA BFKL vertices are just the ones needed to treat semi-hard central production at collider energies in this approach.In our calculation we use one particular element of the NLLA BFKL formalism [2,8], namely the effective vertex for quark-antiquark production. Thus our calculation can be seen as a first phenomenological application of this vertex which decides whether the NLLA BFKL formalism can be hoped to converge.One special aspect of the reaction we in...

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“…This approach was previously advocated for the study of heavy quark production at high energy hadron colliders [11,12]. Recently, more phenomenological studies were performed along this direction by several groups [13][14][15], and some successes seem to be achieved by comparing the calculations with experimental data on heavy quark production at the DESY HERA and the Fermilab Tevatron [14][15][16]. Especially for b andb production, the k t factorization approach may provides a successful resolution for the long standing conflict between the NLO collinear parton model prediction and the experimental data at the Tevatron [15].…”

mentioning

confidence: 99%

Polarizations ofJ/ψandψ′in Hadroproduction at the Tevatron in the
Yuan
¹
,
Kong
²

2001
Phys. Rev. Lett.
39
6
20
0
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We present a calculation for the polarizations of J/ψ and ψ ′ produced in the hadron collisions at the Fermilab Tevatron. Various color octet channels including 1 S (8) 0 , 3 P (8) J , and 3 S (8) 1 as well as contributions from χ cJ decays are considered in the k t factorization approach. We find that in a rather wide range of the transverse momenta of J/ψ and ψ ′ , the production rates could be dominated by the 1 S (8) 0 channel, and the predicted polarizations from the Typeset using REVT E X

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Heavy quark production in parton model and in QCD

Cited by 30 publications

References 5 publications

A solution of the DGLAP equation for gluon at low x

A solution of the DGLAP equation for gluon at low x

Heavy-quark production as a sensitive test for an improved description of high-energy hadron collisions

Polarizations ofJ/ψandψ′in Hadroproduction at the Tevatron in the
Yuan
¹
,
Kong
²

2001
Phys. Rev. Lett.
39
6
20
0
View full text Add to dashboard Cite

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Heavy quark production in parton model and in QCD

Cited by 30 publications

References 5 publications

A solution of the DGLAP equation for gluon at low x

A solution of the DGLAP equation for gluon at low x

Heavy-quark production as a sensitive test for an improved description of high-energy hadron collisions

Polarizations ofJ/ψandψ′in Hadroproduction at the Tevatron in theYuan1, Kong2 2001Phys. Rev. Lett.396200View full textAdd to dashboardCite

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Polarizations ofJ/ψandψ′in Hadroproduction at the Tevatron in the
Yuan
¹
,
Kong
²

2001
Phys. Rev. Lett.
39
6
20
0
View full text Add to dashboard Cite