1,663 research outputs found

    Differential cross sections for top pair production at the LHC

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    We present results of phenomenological studies for top-quark pair production at the LHC at the center of mass energy S=7\sqrt{S} = 7 TeV. The transverse momentum and rapidity distributions for final-state top quarks are calculated in perturbative QCD at approximate next-to-next-to-leading order O(αs4){\cal O}(\alpha_s^4) by using methods of threshold resummation beyond the leading logarithmic accuracy. The theoretical predictions are obtained by using the computer code \textsc{DiffTop} and are compared to recent measurements by the ATLAS and CMS collaborations. \textsc{Difftop} can be employed in the general case of heavy-quark pair production at hadron-hadron colliders and provides a basis for applications in QCD analyses for parton distribution functions determination.Comment: 6 pages, 2 figures, Conference proceedings for DIS2014, XXII International Workshop on Deep-Inelastic Scattering and Related Subjects, 28 April - 2 May 2014, Warsaw, Poland, and ICHEP 2014, 37 International Conference on High Energy Physics, 2-9 July 2014, Valencia, Spai

    Top-quark production at the LHC: differential cross section and phenomenological applications

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    We discuss top-quark pair production at hadron colliders and review available calculations of differential top-pair production cross section in perturbative QCD at approximate next-to-next-to-leading order (NNLO) within the threshold resummation formalism. These calculations are implemented into an open source program under development. We present phenomenological studies at the LHC that include transverse momentum and rapidity distribution of the top quarks at a center-of-mass energy of 7 TeV. Preliminary results obtained with this program are in very good agreement with the recent LHC measurements.Comment: 5 pages, 2 Figures, conference proceeding, DIS2013: XXI International Workshop on Deep-Inelastic Scattering and Related Subjects 22-26 April 2013, Marseilles, Franc

    Top-quark pair production at hadron colliders: differential cross section and phenomenological applications with DiffTop

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    The results of phenomenological studies of top-quark pair production in proton-proton collisions are presented. Differential cross sections are calculated in perturbative QCD at approximate next-to-next-to-leading order O(αs4){\cal O}(\alpha_s^4) by using methods of threshold resummation beyond the leading logarithmic accuracy. Predictions for the single-particle inclusive kinematics are presented for transverse momentum and rapidity distributions of final-state top quarks. Uncertainties related to the description of proton structure, top-quark mass and strong coupling constant are investigated in detail. The results are compared to the recent measurements by the ATLAS and CMS collaborations at the LHC at the center of mass energy of 7 TeV. The calculation presented here is implemented in the computer code \textsc{Difftop} and can be applied to the general case of heavy-quark pair production at hadron-hadron colliders. For the first time, a fit of parton distribution functions at NNLO is performed by using the differential cross sections of top-quark pair production together with other data sets. The impact of the top-pair production on the precision of the gluon distribution at high scales is illustrated.Comment: 30 pages, 12 figures, 2 tables, regular article. Version accepted for a publication on JHE

    Calibration of the Top-Quark Monte Carlo Mass

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    Single-differential top quark pair production cross sections with running mass schemes at NLO

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    Single-differential cross section predictions for top quark pair production are presented at next-to-leading order, using running top quark mass renormalization schemes. The evolution of the mass of the top quark is performed in the MSR scheme mtMSR(μ)m_{\mathrm{t}}^{\textrm{MSR}}(\mu) for renormalization scales μ\mu below the MS\overline{\textrm{MS}} top quark mass mt(mt)\overline{m}_{\mathrm{t}}(\overline{m}_{\mathrm{t}}), and in the MS\overline{\textrm{MS}} scheme mt(μ)\overline{m}_{\mathrm{t}}(\mu) for scales above. In particular, the implementation of a mass renormalization scale independent of the strong coupling renormalization scale and factorization scale in quantum chromodynamics allows investigating independent dynamical scale variations. Furthermore, the first theoretically consistent extraction of the top quark MSR mass from experimental data is presented.Comment: To appear in the Proceedings of the 41st International Conference on High Energy physics - ICHEP2022, Bologna, Italy, 6-13 July, 202

    DIS structure functions and the double-spin asymmetry in rho(0) electroproduction within a Regge approach

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    The proton, neutron and deuteron structure functions F2(x,Q2) and g1(x,Q2), measured at intermediate Q2, are analyzed within a Regge approach. This analysis serves to fix the parameters of this scheme which are then used to calculate, in a unified Regge approach, the properties of ρ0 meson electroproduction on the proton and the deuteron. In this way, the double-spin asymmetry observed at HERMES in ρ0 electroproduction on the proton, can be related to the anomalous behavior of the flavor-singlet part of the spin-dependent structure function g1(x,Q2) at small x

    Impact of heavy-flavour production cross sections measured by the LHCb experiment on parton distribution functions at low x

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    The impact of recent measurements of heavy-flavour production in deep inelastic epep scattering and in pppp collisions on parton distribution functions is studied in a QCD analysis in the fixed-flavour number scheme at next-to-leading order. Differential cross sections of charm- and beauty-hadron production measured by LHCb are used together with inclusive and heavy-flavour production cross sections in deep inelastic scattering at HERA. The heavy-flavour data of the LHCb experiment impose additional constraints on the gluon and the sea-quark distributions at low partonic fractions xx of the proton momentum, down to x5×106x \sim 5 \times 10^{-6}. This kinematic range is currently not covered by other experimental data in perturbative QCD fits

    Pengembangan media pembelajaran berbasis ICT: konsep dan aplikasi pada pembelajaran Pendidikan Agama Islam

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    Dunia pendidikan sudah saatnya dapat memetik manfaat dari perkembangan teknologi informatika yang begitu pesat. Mungkin sudah bukan zamannya pendidik menyampaikan materi secara oral mulai awal sampai akhir pembelajaran, di samping melelahkan juga akan membosankan peserta didik. Ada beberapa media pembelajaran yang dapat difungsikan misalnya, media visual, media audio visual, media komputer, media berbasis internet, dan lain-lain. Buku ini berbicara tentang Pengembangan Media Pembelajaran berbasis ICT, Kajian dan Aplikasi pada pembelajaran Pendidikan Agama Islam. Dalam buku ini dipaparkan berbagai macam media pembelajaran, fungsi, kelebihan dan kekurangannya. Juga disajikan cara memanfaatkan media internet untuk mengembangkan materi Pendidikan Agama Islam. Dengan demikian, pendidik dapat memilah dan memilih media yang tepat untuknya, sekaligus pendidik dapat berinovasi serta mengembangkan pembelajaran yang kreatif dan inovatif

    The PDF4LHC report on PDFs and LHC data: Results from Run I and preparation for Run II

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    The accurate determination of the Parton Distribution Functions (PDFs) of the proton is an essential ingredient of the Large Hadron Collider (LHC) program. PDF uncertainties impact a wide range of processes, from Higgs boson characterisation and precision Standard Model measurements to New Physics searches. A major recent development in modern PDF analyses has been to exploit the wealth of new information contained in precision measurements from the LHC Run I, as well as progress in tools and methods to include these data in PDF fits. In this report we summarise the information that PDF-sensitive measurements at the LHC have provided so far, and review the prospects for further constraining PDFs with data from the recently started Run II. This document aims to provide useful input to the LHC collaborations to prioritise their PDF-sensitive measurements at Run II, as well as a comprehensive reference for the PDF-fitting collaborations.Comment: 55 pages, 13 figure
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