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A. Vafaee

Publications and source records attributed to A. Vafaee.

7 recordsLinked to original sources

NNLO compatibility between pQCD theory and phenomenology in determination of the $b$-quark pole and \MSbar running masses

This contribution attempts to determine the $b$-quark pole mass $M_b$ and \MSbar running mass $\overline{m}_b$ with two different approaches at the next-to-next-to-leading order (NNLO) corrections. At the first approach, we derive a relation between the $b$-quark pole mass $M_b$ and its \MSbar running mass $\overline{m}_b$ at the NNLO corrections based on the perturbative Quantum Chromo Dynamics (pQCD) predictions. At the second approach, we extract numerical values of the $b$-quark pole and \MSbar running masses based on the NNLO phenomenology of H1 and ZEUS Collaborations combined beauty vertex production experimental data. Then we discuss about the compatibility between the pQCD theory results and phenomenology approach in determination of the $b$-quark pole and \MSbar running masses at the NNLO corrections. Also, we investigate the role and influence of the $b$-quark mass as an extra degree of freedom added to the input parameters of the Standard Model Lagrangian, on the improvement of the uncertainty band of the proton parton distribution functions (PDFs) and particularly on the gluon distribution.

hep-ph

The effect of LHC ATLAS jet production cross sections data at $ \sqrt{s} = 7$ TeV on the proton PDFs up to N3LO

The effect of full $7$ sets of LHC ATLAS jet cross sections data at $ \sqrt{s} = 7$ TeV on the proton parton distribution functions (PDFs) up to next-to-next-to-next-to-leading order (NNNLO or N3LO) corrections is investigated for the first time. Phenomenologically, the proton central PDFs in this perturbative Quantum Chromo Dynamics (pQCD) analysis are defined based on the full seven data sets from HERA I and II combined. It is shown that, the LHC ATLAS jet cross sections data at $ \sqrt{s} = 7$ TeV on the HERA I and II combined data reduces the error band of proton PDFs. Particularly, the uncertainties of the gluon $xg(x,Q^2)$ and charm $xc(x,Q^2)$ distributions decrease dramatically. Adding the LHC ATLAS jet cross sections data at $ \sqrt{s} = 7$ TeV on the central proton PDFs improves the quality of the fit up to $\sim 1.53$ \%, $\sim 2.72$ \% and $\sim 2.80$ \% corresponding to next-to-leading order (NLO), next-to-next-to leading order (N2LO) and N3LO, respectively.

hep-ph

The pQCD analysis to extract PDFs and $\alpha_s^{{\rm NLO}}(M^2_Z)$ from inclusive jet-hadron production data

This perturbative Quantum Chromo Dynamics (pQCD) analysis attempts to present a simultaneous determination of parton distribution functions (PDFs) and the strong coupling $\alpha_s(M^2_Z)$ from inclusion of inclusive H1 and ZEUS jet, DiJets and TriJets production cross sections data on the HERA I and II combined data, as the central data sets for probing the internal structure of proton. To present an accurate pQCD analysis, we separate the role and influence of inclusion jet production cross sections data from inclusion of the strong coupling $\alpha_s(M^2_Z)$ as an extra fit parameter parameter on the gluon distribution. We show inclusion of jet, DiJets and TriJets production cross sections data improves the consistency between experiment and theory of cross sections for neutral current (NC) and charged current (CC) interactions of deep inelastic ${e^\pm}p$ scattering on proton up to $\sim 2.8$~\%. In addition, we show inclusion of jet production cross section data and considering $\alpha_s(M^2_Z)$ as a pQCD free parameter not only reduce dramatically the uncertainty band of gluon distribution but also improve the consistency between experiment and theory of NC and CC deep inelastic ${e^\pm}p$ scattering cross sections up to $\sim 3.6$~\%. Our simultaneous determination of PDFs and the strong coupling $\alpha_s(M^2_Z)$ with inclusion of jet production cross sections data leads to $\alpha_s^{{\rm NLO}}(M^2_Z) = 0.12041 \pm 0.00086$, which is in a good agreement with world average and other individual measurements.

hep-ph

Charm-quark pole mass from HERA Combined and LHCb charm production data

One of the most popular definition for the charm-quark mass is the charm-quark pole mass $m_c^{\rm pole}$. In this contribution, we extract the charm-quark pole mass through perturbative Quantum Chromo Dynamics (pQCD) analysis up to the next-to-next-to-leading order (NNLO) corrections from HERA Combined and LHCb charm production recent data sets. Then, we investigate for the first time the charm-quark pole mass $m_c^{\rm pole}$ pure impact, as an extra pQCD parameter on the proton Parton Distribution Functions (PDFs) at the NNLO corrections.

hep-ph

Impact of Beauty and Charm H1-ZEUS Combined Measurements on PDFs and Determination of the Strong Coupling

In this QCD analysis, we investigate the impact of recent measurements of heavy-flavor charm and beauty cross sections data sets on the simultaneous determination of Parton Distribution Functions (PDFs) and the strong coupling, $\alpha_s(M^2_Z)$. We perform three different fits based on Variable-Flavour Number Scheme (VFNS) at the Leading Order (LO) and Next-to-Leading Order (NLO) and choose the full HERA run I and II combined data as a new measurement of inclusive Deep Inelastic Scattering (DIS) cross sections for our base data set. We show that including charm and beauty cross sections data reduces the uncertainty of gluon distribution and improves the fit quality up to 4.1\% from leading order to next-to-leading order and up to 1.7\% for only NLO without and with beauty and charm data contributions.

hep-ph

The Role of Different Schemes in the QCD Analysis and Determination of the Strong Coupling

In this article, we present a Next-to-Leading Order (NLO) QCD analysis to study the role and influence of different schemes on simultaneous determination of the Parton Distribution Functions (PDFs) and strong coupling, $\alpha_s(M^2_Z)$. We perform our analysis based on three different data sets, HERA I and II combined data, H1-ZEUS charm combined data, and H1 and ZEUS beauty production cross sections data, in two different Thorne-Roberts (TR or RT) and Thorne-Roberts Optimal (RT OPT) schemes. We show in going from RT scheme to RT OPT scheme, in addition of reduction the uncertainty of some PDFs, specially for the gluon distribution, we get $\sim 0.4$~\% and $\sim 0.7$~\%~improvement in the fit quality and $\sim 0.9$~\% and $\sim 1.6$~\%~improvement for the strong coupling, $\alpha_s(M^2_Z)$, without and with heavy flavor contributions, respectively.

hep-ph

Impact of Charm H1-ZEUS Combined data and Determination of the Strong Coupling in Two Different Schemes

We study the impact of recent measurements of charm cross section H1-ZEUS combined data on simultaneous determination of parton distribution functions (PDFs) and the strong coupling, $\alpha_s(M^2_Z)$, in two different schemes. We perform several fits based on Thorne-Roberts (RT) and Thorne-Roberts optimal (RTOPT) schemes at next-to-leading order (NLO). We show that adding charm cross section H1-ZEUS combined data reduces the uncertainty of the gluon distribution and improves the fit quality up to $\sim 0.4$~\% and $\sim 0.9$~\%~, without and with the charm contribution, from the RT scheme to the RTOPT scheme, respectively. We also emphasise the central role of the strong coupling, $\alpha_s(M^2_Z)$, in revealing the impact of charm flavour contribution, when it is considered as an extra free parameter. We show that in going from the RT scheme to the RT OPT scheme, we get $\sim 0.9$~\% and $\sim 2.0$~\%~improvement in the value of $\alpha_s(M^2_Z)$, without and with the charm flavour contribution respectively.

hep-ph