Scale dependence of polarized deep inelastic scattering asymmetries

Canal, C. A. García; Joffily, S.; Sassot, R.

doi:10.1103/physrevd.53.73

Cited by 26 publications

(47 citation statements)

References 19 publications

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“…With this definition of factorization in the case P 2 = 0 we make sure that we obtain the same NLO corrections as in [19], where P 2 = 0, when in the P 2 = 0 calculation we choose P 2 extremely small. So, for the actual calculations we apply the formulas (2)- (5) where M is now given by (13). We note that for averaging over the spin of initial gluons and photons we apply a factor 1/(2 − 2ǫ), that gives rise to some additional finite terms which should be included in (9) when expanded in ǫ.…”

Section: Subtraction Of Photon Initial State Singularitiesmentioning

confidence: 99%

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Inclusive jet production with virtual photons in next-to-leading order QCD

1998

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We present a next-to-leading order calculation for the virtual photoproduction of one and two jets in ep collisions. Soft and collinear singularities are extracted using the phase space slicing method. The collinear photon initial state singularity depends logarithmically on the mass of the virtual photon and is absorbed into the virtual photon structure function. An MS factorization scheme is defined similarly to the real photon case. Numerical results are presented for HERA conditions using the Snowmass jet definition for inclusive single jet and dijet cross sections. We study the dependence of these cross sections on the transverse energies and rapidities of the jets. Finally, we compare the ratio of the experimentally defined resolved and direct cross sections with recent ZEUS data as a function of the photon virtuality P 2 .

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Section: Subtraction Of Photon Initial State Singularitiesmentioning

confidence: 99%

“…It is expected that the resolved component decreases relative to the contribution from the direct photon processes as the virtuality of the photon increases. Some theoretical studies of the single inclusive and dijet inclusive cross section in LO have been presented recently [12,13,14].…”

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confidence: 99%

Inclusive jet production with virtual photons in next-to-leading order QCD

1998

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“…LX, ep ! LX) where all relevant coefficient functions are now available at next-to-leading order (NLO) [2,[6][7][8]. In various analyses of processes sensitive to polarized parton distributions it has turned out to be particularly useful to study distributions differential in the rapidity of a produced particle [9], on which we will therefore focus also in the present analysis.…”

mentioning

confidence: 99%

PolarizedΛ-Baryon Production inppCollisions

1998

Self Cite

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We study the production of longitudinally polarized L baryons in single-spin p p collisions at BNL RHIC and DESY HERA-N as a means of determining the spin-dependent L fragmentation functions. It is shown that a measurement of the rapidity distribution of the L's would provide an excellent way of clearly discriminating between various recently suggested sets of polarized L fragmentation functions that are all compatible with present e 1 e 2 data. We also address the main theoretical uncertainties, which appear to be well under control. [S0031-9007(98)06651-4] PACS numbers: 13.88. + e, 13.85. Ni, 13.87.Fh, 14.20.Jn The understanding of spin-dependent deep-inelastic scattering (DIS) processes in terms of QCD-evolved polarized parton distributions Df͑x, Q 2 ͒ ͑ f q,q, g͒ is still far from being satisfactory, despite significant experimental and theoretical progress over the past few years. In particular, the angular momentum component of the proton's spin and the polarized gluon density Dg͑x, Q 2 ͒ remain almost completely unknown for the time being, and more experimental results are required.Studies of spin-transfer reactions could provide further invaluable and completely new insight into the field of "spin physics" and, in addition, might also yield a better understanding of the hadronization process. Such cross sections can be expressed as convolutions of perturbatively calculable partonic spin-transfer cross sections with certain sets of parton distributions and fragmentation functions, whose scale dependence is completely predicted by QCD once a suitable nonperturbative input at some reference scale has been determined by data. To obtain a nonvanishing twist-2 spin-transfer asymmetry, the measurement of the polarization of one outgoing particle is obviously required, in addition to having a polarized beam or target. This certainly provides a great experimental challenge. L-baryons are particularly suited for such studies due to the self-analyzing properties of their dominant weak decay L ! pp 2 , and recent results on L production reported from large electron-positron collider (LEP) [1] have demonstrated the experimental feasibility of successfully reconstructing the L spin.In [2] a first attempt was made to determine the spindependent L fragmentation functions by analyzing these LEP data [1] in leading and next-to-leading order QCD, using the results of a preceding study of unpolarized L fragmentation functions. Unfortunately it turned out, however, that the available LEP data, all obtained on the Z resonance and, hence, sensitive only to the flavor nonsinglet part of the cross section, cannot even sufficiently constrain the valence fragmentation functions for all flavors.Rather different, but all physically conceivable, scenarios adopted for the input valence distributions appear to describe the data equally well, and for the "unfavored" sea quark and gluon fragmentation functions one has to fully rely on mere assumptions. Clearly, further measurements of other helicity transfer processes are required to ...

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“…The situation in NLO [4,17] is much more complicated than in LO, since factorization is replaced by convolution, and it is also more complicated than inclusive DIS in NLO since here one has to contend with double convolutions of the form q ⊗ C ⊗ D and ∆q ⊗ ∆C ⊗ D for the unpolarized and polarized cases respectively, where C and ∆C are Wilson coefficients first derived in [17] and [4].…”

Section: Semi-inclusive Analysis In Nlo Qcdmentioning

confidence: 99%

“…involving the detection of the produced hadron h. The theoretical structure for the analysis of such reactions, in both leading order QCD (LO) and next-to-leading order (NLO), exists [4]. However we are critical of the type of LO analysis carried out thus far by the experimental groups.…”

Section: Introductionmentioning

confidence: 99%

A strategy for the analysis of semi-inclusive deep inelastic scattering

Christova

Leader

2001

Nuclear Physics B

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We present a strategy for the systematic extraction of a vast amount of detailed information on polarized parton densities and fragmentation functions from semi-inclusive deep inelastic scattering l + N → l + h + X, in both LO and NLO QCD. A method is suggested for estimating the errors involved in the much simpler, and therefore much more attractive, LO analysis. The approach is based upon a novel interplay with data from inclusive DIS and from e + e − → hX, and leads to a much simplified form of the NLO expressions. No assumptions are made about the equality of any parton densities and the only symmetries utilised are charge conjugation invariance and isotopic spin invariance of strong interactions.

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Scale dependence of polarized deep inelastic scattering asymmetries

Cited by 26 publications

References 19 publications

Inclusive jet production with virtual photons in next-to-leading order QCD

Inclusive jet production with virtual photons in next-to-leading order QCD

PolarizedΛ-Baryon Production inppCollisions

A strategy for the analysis of semi-inclusive deep inelastic scattering

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