Impact of PDF uncertainties at large x on heavy boson production

Brady, Lucas T.; Accardi, Alberto; Melnitchouk, Wally; Owens, J. F.

doi:10.1007/jhep06(2012)019

Cited by 30 publications

(34 citation statements)

References 55 publications

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“…As discussed in the introduction, global QCD fits allow for the intriguing possibility to combine deuteron and proton target data to obtain experimental constraints on nuclear models, and at the same time fully utilize the available statistics of the nuclear target data. For example, the directly reconstructed W asymmetry at Tevatron is very sensitive to nuclear corrections at y 2 [9]. A comparison with the very precise CDF data as well as the total χ 2 values in the CJ12 fits suggest that nuclear effects are somewhere between the minimum and central ones considered in the CJ12min and CJ12mid fits, respectively.…”

Section: Pos(dis 2013)040mentioning

confidence: 94%

“…However, a relatively modest improvement in statistical precision and reduction of nuclear uncertainty would allow one to restrict the range of allowable physical mechanisms. The same nuclear uncertainty also affects forward rapidity observables or production of large mass particles [9]. For example, the nuclear uncertainty becomes relevant for W production at rapidity larger than 2 at the Tevatron, and larger than 3.5 at the LHC.…”

Section: Pos(dis 2013)040mentioning

confidence: 99%

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The CJ12 parton distributions

Accardi¹,

Owens²

2013

Proceedings of XXI International Workshop on Deep-Inelastic Scattering and Related Subjects — PoS(DIS 2013)

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Three new sets of next-to-leading order parton distribution functions (PDFs) are presented. These are determined by global fits to a wide variety of data for hard scattering processes. The analysis includes target mass and higher twist corrections needed for the description of deep inelastic scattering data at large x and low Q 2 , and nuclear corrections for deuterium targets. The PDF sets correspond to three different models for the nuclear effects, and provide a more realistic uncertainty range for the d quark PDF compared with previous fits. Applications, in particular to weak boson production at colliders, are also be discussed. Deep-Inelastic Scattering and Related Subject -DIS2013, 22-26 April 2013 Marseilles,France * Speaker. XXI International Workshop on PoS(DIS 2013)040The CJ12 parton distributions A. AccardiIntroduction. Plentiful DIS data exist from fixed-target experiments at large x and low scale Q 2 , which is typically excluded in global QCD fits by imposing cuts on the invariant mass W 3.8 GeV in order to exclude the region where higher-twists and other subleading in 1/Q 2 effects are important. However, there are many reason why one should try and obtain precise PDFs at large x. For example, they are necessary to reduce the uncertainty on the QCD background in searches for new physics in high p T spectra or large mass at the LHC. On the other end of the energy spectrum, the behavior of ratios like d/u or ∆u/u and ∆d/d at x → 1 can discriminate between models of the non perturbative structure of the nucleon. Finally, the uncertainty in the extraction of the helicity gluon PDF at the smallest x, which can be reached in forward particle production in p + p collisions, is fundamentally limited by the PDF uncertainty on the large-x quark against which the gluon scatters. While these are certainly noble and necessary goals, the most interesting aspect of large-x global fits is their ability to connect particle physics at high-energy with hadronic and nuclear physics at medium energy [1]. For example, data on W and Z forward rapidity boson production at Tevatron and the LHC, which can reach large values of x, can constrain the extrapolation to x = 1 of the down-quark to up-quark ratio in the proton, and (with enough statistical precision) indicate which nonperturbative proton structure model best captures the effects of confinement on hadron structure. Likewise, but less obviously, global PDF fits can be used as a tool to study the structure of the nucleus and the differences between bound and free protons, for which current models display large theoretical uncertainties. This is possible, e.g., by exploiting the interplay of Deep Inelastic Scattering (DIS) data in deuteron targets, which allow one to extract a nuclear model dependent d quark distribution at large x [2 -4], and weak interaction processes on proton targets, which also depend on the d quark but are naturally free from nuclear effects. Global fits can thus turn detectors such as CDF at the Tevatron or LHCb at the LHC into nuclear phy...

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Section: Pos(dis 2013)040mentioning

confidence: 94%

Section: Pos(dis 2013)040mentioning

confidence: 99%

The CJ12 parton distributions

Accardi¹,

Owens²

2013

Proceedings of XXI International Workshop on Deep-Inelastic Scattering and Related Subjects — PoS(DIS 2013)

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“…Stable fits of leading twist PDFs could be obtained [6] for W down to ∼ 3 GeV and Q 2 > ∼ 1.7 GeV 2 , as long as TMC and higher twist corrections were accounted for. Aside from its intrinsic value, better knowledge of PDFs at large x may also be important for searches of new physics signals in collider experiments such as at the Tevatron or the LHC at large rapidities or for heavy mass particles [14], as well as at more central rapidities where uncertainties in large-x PDFs at low Q 2 can, through Q 2 evolution, affect cross sections at small x and large Q 2 [15].…”

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confidence: 99%

Next-to-leading order analysis of target mass corrections to structure functions and asymmetries

et al. 2011

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We perform a comprehensive analysis of target mass corrections (TMCs) to spin-averaged structure functions and asymmetries at next-to-leading order. Several different prescriptions for TMCs are considered, including the operator product expansion, and various approximations to it, collinear factorization, and ξ-scaling. We assess the impact of each of these on a number of observables, such as the neutron to proton F 2 structure function ratio, and parity-violating electron scattering asymmetries for protons and deuterons which are sensitive to γZ interference effects.The corrections from higher order radiative and nuclear effects on the parity-violating deuteron asymmetry are also quantified.

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“…Indeed, a novel aspect of large-x global fits is their ability to connect elements of high-energy physics with hadronic and nuclear physics at medium energy [1,10]. For example, data on W and Z boson production at forward rapidity at the Tevatron and LHC, that extend to large values of x, can constrain the extrapolation of PDFs to x = 1, where these are sensitive to different mechanisms of quark confinement [11,12].…”

Section: Introductionmentioning

confidence: 99%

PDFs from protons to nuclei

Accardi¹

2016

Proceedings of XXIII International Workshop on Deep-Inelastic Scattering — PoS(DIS2015)

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I review recent progress in the extraction of unpolarized parton distributions in the proton and in nuclei from a unified point of view that highlights how the interplay between high-energy particle physics and lower energy nuclear physics can be of mutual benefit to either field in areas ranging from the search for physics beyond the standard model at the LHC, to the study of the non perturbative structure of nucleons and teh emergence of nuclei from quark and gluon degrees of freedom, to the interaction of colored probes in a cold nuclear medium.

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Impact of PDF uncertainties at large x on heavy boson production

Cited by 30 publications

References 55 publications

The CJ12 parton distributions

The CJ12 parton distributions

Next-to-leading order analysis of target mass corrections to structure functions and asymmetries

PDFs from protons to nuclei

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