Parton distribution functions and constraints on the intrinsic charm content of the proton using the Brodsky-Hoyer-Peterson-Saka approach

Abstract

In this work, a new set of parton distribution functions taking into account the intrinsic charm (IC) contribution is presented. We focus on the impact of the EMC measurements on the large x charm structure function as the strongest evidence for the intrinsic charm when combined with the HERA, SLAC and BCDMS data. The main goal of this paper is the simultaneous determination of the intrinsic charm probability P cc/p and strong coupling αs. This allows us to study the interaction of these two quantities as well as the influence on the PDFs in the presence of IC contributions. By considering αs which can be fix or free parameter from our QCD analysis, we find that although there is not a significant change in the extracted central value of PDFs and their uncertainties, the obtained value of P cc/p change by factor 7.8%. The extracted value of P cc/p in the present QCD analysis is consistent with the recent reported upper limit of 1.93%, which is obtained for the first time from LHC measurements. We show the intrinsic charm probability is sensitive to the strong coupling constant and also the charm mass. The extracted value of the strong coupling constant αs(M 2 Z ) = 0.1191 ± 0.0008 at NLO is in good agreement with world average value and available theoretical models.

Constraints on Gluon Distribution Functions in the Nucleon and Nucleus from Open Charm Hadron Production at the Electron-Ion Collider

“…We have also repeated this exercise with the NNPDF3 PDF set 1 where the intrinsic charm content of the proton 1 We explicitly use the NNPDF3 IC nlo as 0118 mcpole 1470 and NNPDF3 nIC nlo as 0118 mcpole 1470 PDF sets provided by the NNPDF collaboration 3.1 [3] 5 [4] 8 [5] 12 [6] 20 [7] 31 [8] 52 [9] 76 [10] 120 [11] is determined using a "fitted" charm method [31]. The IC PDF from the NNPDF analyses is comparable to the BHPS1 model in the CT14 analysis and peaks at slightly large values of x p , and has a total momentum fraction also on the order of 1%.…”

“…These studies show at the EIC measurements of charm structure functions will be extremely sensitive to the existence of IC and to different IC models. 3.1 [3] 5 [4] 8 [5] 12 [6] 20 [7] 31 [8] 52 [9] 76 [10] 120 [11] -1 =10 fb L =63,29 GeV, s PYTHIA e+p with the baseline CT14 PDF (black points), CT14 with sea-like intrinsic charm (dashed black lines), and CT14 with BHPS-like intrinsic charm (red lines), for two representative values of Q 2 . The statistical uncertainties are scaled to 10 fb −1 .…”

“…Therefore, an understanding of the IC PDF which will be important for precise and accurate (n)PDF determinations from global fits, must come from experimental data. Most analyses find an IC component at large values of x p stemming from the large charm quark mass [7][8][9][10][11][12] (also for intrinsic bottom [13]). This limits the constraints from existing DIS data.…”

Probing the strange content of the proton with charm production in charged current at LHeC

“…Here, f g→s is the perturbative splitting of the gluon into an ss pair; the leading term is proportional to: 10 f g→s (x, μ) ∼ α S (μ) 2π P (1) g→s (x) ln . 9 Note, there are also corresponding quark-initiated processes; we will focus on the gluon-initiated processes as this is sufficient to illustrate our points. Both the gluon-and quark-initiated contributions are included in our calculations.…”

“…In the Standard Model (SM), the charm quark plays an important role in the investigation of the nucleon structure [6][7][8][9]. In the NC case, the photon-gluon fusion process for charm production was calculated at O(α 2 s ) with the full heavy-quark mass dependence included in the DIS hard cross sections [10,11].…”