A Mathematica interface to NNPDFs

We present a Mathematica interface for handling the parton distribution functions of the NNDPF Collaboration, available from the NNPDF hepforge website http://nnpdf.hepforge.org/. As a case study we briefly summarise the first PDF set which includes all relevant LHC data, NNPDF2.3, and demonstrate the use of our new Mathematica interface.Comment: 4 pages, 5 figures, to appear in the proceedings of the 16th International Conference in Quantum Chromodynamics (QCD2012), Montpellier July 201

APFELgrid: a high performance tool for parton density determinations

We present a new software package designed to reduce the computational burden of hadron collider measurements in Parton Distribution Function (PDF) fits. The APFELgrid package converts interpolated weight tables provided by APPLgrid files into a more efficient format for PDF fitting by the combination with PDF and $\alpha_s$ evolution factors provided by APFEL. This combination significantly reduces the number of operations required to perform the calculation of hadronic observables in PDF fits and simplifies the structure of the calculation into a readily optimised scalar product. We demonstrate that our technique can lead to a substantial speed improvement when compared to existing methods without any reduction in numerical accuracy.Comment: 13 pages, 2 figures. Submitted to CPC. Code available from https://github.com/nhartland/APFELgri

A determination of the fragmentation functions of pions, kaons, and protons with faithful uncertainties

We present NNFF1.0, a new determination of the fragmentation functions (FFs) of charged pions, charged kaons, and protons/antiprotons from an analysis of single-inclusive hadron production data in electron-positron annihilation. This determination, performed at leading, next-to-leading, and next-to-next-to-leading order in perturbative QCD, is based on the NNPDF methodology, a fitting framework designed to provide a statistically sound representation of FF uncertainties and to minimise any procedural bias. We discuss novel aspects of the methodology used in this analysis, namely an optimised parametrisation of FFs and a more efficient $\chi^2$ minimisation strategy, and validate the FF fitting procedure by means of closure tests. We then present the NNFF1.0 sets, and discuss their fit quality, their perturbative convergence, and their stability upon variations of the kinematic cuts and the fitted dataset. We find that the systematic inclusion of higher-order QCD corrections significantly improves the description of the data, especially in the small-$z$ region. We compare the NNFF1.0 sets to other recent sets of FFs, finding in general a reasonable agreement, but also important differences. Together with existing sets of unpolarised and polarised parton distribution functions (PDFs), FFs and PDFs are now available from a common fitting framework for the first time.Comment: 50 pages, 22 figures, 5 table

Parton distributions with threshold resummation

We construct a set of parton distribution functions (PDFs) in which fixed-order NLO and NNLO calculations are supplemented with soft-gluon (threshold) resummation up to NLL and NNLL accuracy respectively, suitable for use in conjunction with any QCD calculation in which threshold resummation is included at the level of partonic cross sections. These resummed PDF sets, based on the NNPDF3.0 analysis, are extracted from deep-inelastic scattering, Drell-Yan, and top quark pair production data, for which resummed calculations can be consistently used. We find that, close to threshold, the inclusion of resummed PDFs can partially compensate the enhancement in resummed matrix elements, leading to resummed hadronic cross-sections closer to the fixed-order calculation. On the other hand, far from threshold, resummed PDFs reduce to their fixed-order counterparts. Our results demonstrate the need for a consistent use of resummed PDFs in resummed calculations.Comment: 43 pages, 17 figures, accepted for publication in JHE

Boosting Higgs pair production in the bbˉbbˉb\bar{b}b\bar{b} final state with multivariate techniques

The measurement of Higgs pair production will be a cornerstone of the LHC program in the coming years. Double Higgs production provides a crucial window upon the mechanism of electroweak symmetry breaking and has a unique sensitivity to the Higgs trilinear coupling. We study the feasibility of a measurement of Higgs pair production in the $b\bar{b}b\bar{b}$ final state at the LHC. Our analysis is based on a combination of traditional cut-based methods with state-of-the-art multivariate techniques. We account for all relevant backgrounds, including the contributions from light and charm jet mis-identification, which are ultimately comparable in size to the irreducible $4b$ QCD background. We demonstrate the robustness of our analysis strategy in a high pileup environment. For an integrated luminosity of $\mathcal{L}=3$ ab$^{-1}$, a signal significance of $S/\sqrt{B}\simeq 3$ is obtained, indicating that the $b\bar{b}b\bar{b}$ final state alone could allow for the observation of double Higgs production at the High-Luminosity LHC.Comment: 47 pages, 22 figures. v2: updated references, added comparison of post-MVA kinematic distributions. v3: matches published version in EPJ

MCgrid:projecting cross section calculations on grids

MCgrid is a software package that provides access to the APPLgrid interpolation tool for Monte Carlo event generator codes, allowing for fast and flexible variations of scales, coupling parameters and PDFs in cutting edge leading and next-to-leading-order QCD calculations. This is achieved by providing additional tools to the Rivet analysis system for the construction of MCgrid enhanced Rivet analyses. The interface is based around a one-to-one correspondence between a Rivet histogram class and a wrapper for an APPLgrid interpolation grid. The Rivet system provides all of the analysis tools required to project a Monte Carlo weight upon an observable bin, and the MCgrid package provides the correct conversion of the event weight to an APPLgrid fill call. MCgrid has been tested and designed for use with the SHERPA event generator, however as with Rivet the package is suitable for use with any code which can produce events in the HepMC event record format.Comment: 35 pages, 11 figure

A Monte Carlo global analysis of the Standard Model Effective Field Theory: the top quark sector

We present a novel framework for carrying out global analyses of the Standard Model Effective Field Theory (SMEFT) at dimension-six: SMEFiT. This approach is based on the Monte Carlo replica method for deriving a faithful estimate of the experimental and theoretical uncertainties and enables one to construct the probability distribution in the space of the SMEFT degrees of freedom. As a proof of concept of the SMEFiT methodology, we present a first study of the constraints on the SMEFT provided by top quark production measurements from the LHC. Our analysis includes more than 30 independent measurements from 10 different processes at 8 and 13 TeV such as inclusive top-quark pair and single-top production and the associated production of top quarks with weak vector bosons and the Higgs boson. State-of-the-art theoretical calculations are adopted both for the Standard Model and for the SMEFT contributions, where in the latter case NLO QCD corrections are included for the majority of processes. We derive bounds for the 34 degrees of freedom relevant for the interpretation of the LHC top quark data and compare these bounds with previously reported constraints. Our study illustrates the significant potential of LHC precision measurements to constrain physics beyond the Standard Model in a model-independent way, and paves the way towards a global analysis of the SMEFT.Comment: 76 pages, 24 figures, version accepted for publication in JHE

PENGARUH PENGGUNAAN METODE PEMBELAJARAN KOOPERATIF MAKE A MATCH TERHADAP

bstract: The purpose of this research is to looking for the influence of the using Cooperative learning type make a match to the student’s achievment. This research uses experiment method. The population is all students of 5 grade elementary school Wonogiri Wonogiri. The sample was selected using stratified cluster random sampling. The data resources focused in the achievement learning that gotten by pretest and posttest using questions test that had trough the research of validity, reability, difficulty index and ability of differentiation of question test. The pre-analytic of data are test of balance, normality test, and homogenity test. The technique of analytic of data that used to hipotesis test is t test. The result of the research can be concluded that there is a positif influence of using cooperative learning type make a match to the student’s achievement (t calculate > t table=56,691>2,00). Abstrak: Tujuan penelitian ini adalah untuk mengetahui pengaruh metode pembelajaran kooperatif make a match terhadap hasil belajar IPS. Penelitian ini menggunakan metode eksperimen. Populasi penelitian ini adalah siswa kelas 5 SDN Wonogiri, Wonogiri. Teknik pengambilan sampel yang digunakan adalah stratified cluster random sampling. Sumber data difokuskan pada proses belajar dan hasil belajar yang diperoleh melalui pretest dan posttest dengan instrument soal yang telah melalui uji validitas, reabilitas, indeks kesukaran dan daya pembeda soal. Uji prasyarat analisis menggunakan uji keseimbangan, uji normalitas, uji homogenitas. Sedangkan teknik analisis data sebagai uji hipotesis memakai uji t. Hasil dari penelitian ini dapat disimpulkan ada pengaruh yang positif signifikan model pembelajaran kooperatif Make a Match terhadap hasil belajar IPS (t hitung > t tabel =56,691>2,00). Kata Kunci: Pembelajaran Kooperatif, Make a Matc

Parton distributions from high-precision collider data: NNPDF Collaboration

We present a new set of parton distributions, NNPDF3.1, which updates NNPDF3.0, the first global set of PDFs determined using a methodology validated by a closure test. The update is motivated by recent progress in methodology and available data, and involves both. On the methodological side, we now parametrize and determine the charm PDF alongside the light-quark and gluon ones, thereby increasing from seven to eight the number of independent PDFs. On the data side, we now include the D0 electron and muon W asymmetries from the final Tevatron dataset, the complete LHCb measurements of W and Z production in the forward region at 7 and 8 TeV, and new ATLAS and CMS measurements of inclusive jet and electroweak boson production. We also include for the first time top-quark pair differential distributions and the transverse momentum of the Z bosons from ATLAS and CMS. We investigate the impact of parametrizing charm and provide evidence that the accuracy and stability of the PDFs are thereby improved. We study the impact of the new data by producing a variety of determinations based on reduced datasets. We find that both improvements have a significant impact on the PDFs, with some substantial reductions in uncertainties, but with the new PDFs generally in agreement with the previous set at the one-sigma level. The most significant changes are seen in the light-quark flavor separation, and in increased precision in the determination of the gluon. We explore the implications of NNPDF3.1 for LHC phenomenology at Run II, compare with recent LHC measurements at 13 TeV, provide updated predictions for Higgs production cross-sections and discuss the strangeness and charm content of the proton in light of our improved dataset and methodology. The NNPDF3.1 PDFs are delivered for the first time both as Hessian sets, and as optimized Monte Carlo sets with a compressed number of replicas.V. B., N. H., J. R., L. R. and E. S. are supported by an European Research Council Starting Grant “PDF4BSM”. R. D. B. and L. D. D. are supported by the UK STFC grants ST/L000458/1 and ST/P000630/1. L. D. D. is supported by the Royal Society, Wolfson Research Merit Award, grant WM140078. S. F. is supported by the European Research Council under the Grant Agreement 740006NNNPDFERC-2016-ADG/ERC-2016-ADG. E. R. N. is supported by the UK STFC grant ST/M003787/1. S. C. is supported by the HICCUP ERC Consolidator grant (614577). M. U. is supported by a Royal Society Dorothy Hodgkin Research Fellowship and partially supported by the STFC grant ST/L000385/1. S. F and Z. K. are supported by the Executive Research Agency (REA) of the European Commission under the Grant Agreement PITN-GA-2012-316704 (HiggsTools). A. G. is supported by the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 659128-NEXTGENPDF