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Measurement of the Cross-Section for W Boson Production in Association with b-Jets in Proton-Proton Collisions at TeV at the LHC using the ATLAS detector
This dissertation presents a measurement of the W+b-jets production cross-section in proton–proton collisions at a center-of-mass energy of 7 TeV at the LHC. The results are based on data corresponding to an integrated luminosity of , collected with the ATLAS detector. The measurement probes the QCD sector of the Standard Model at high energy, in a region where b-quark mass and double parton scattering play an important role. In addition, the measurement is relevant for searches for physics beyond the Standard Model in final states with a W boson and b-jets. The measurement relies on the leptonic decay modes of the W, and on the iden- tification of b-jets. The backgrounds to the W+b-jets process are estimated using Monte Carlo simulation and data-driven techniques. Cross-sections, corrected for all known detector effects and quoted in a limited kinematic range, are presented as a function of jet multiplicity and of the transverse momentum of the leading b-jet for both the muon and electron decay modes of the W boson.Physic
Automatic setup of 18 MeV electron beamline using machine learning
To improve the performance-critical stability and brightness of the electron
bunch at injection into the proton-driven plasma wakefield at the AWAKE CERN
experiment, automation approaches based on unsupervised Machine Learning (ML)
were developed and deployed. Numerical optimisers were tested together with
different model-free reinforcement learning agents. In order to avoid any bias,
reinforcement learning agents have been trained also using a completely
unsupervised state encoding using auto-encoders. To aid hyper-parameter
selection, a full synthetic model of the beamline was constructed using a
variational auto-encoder trained to generate surrogate data from equipment
settings. This paper describes the novel approaches based on deep learning and
reinforcement learning to aid the automatic setup of a low energy line, as the
one used to deliver beam to the AWAKE facility. The results obtained with the
different ML approaches, including automatic unsupervised feature extraction
from images using computer vision are presented. The prospects for operational
deployment and wider applicability are discussed
Studying the Underlying Event in Drell-Yan and High Transverse Momentum Jet Production at the Tevatron
We study the underlying event in proton-antiproton collisions by examining
the behavior of charged particles (transverse momentum pT > 0.5 GeV/c,
pseudorapidity |\eta| < 1) produced in association with large transverse
momentum jets (~2.2 fb-1) or with Drell-Yan lepton-pairs (~2.7 fb-1) in the
Z-boson mass region (70 < M(pair) < 110 GeV/c2) as measured by CDF at 1.96 TeV
center-of-mass energy. We use the direction of the lepton-pair (in Drell-Yan
production) or the leading jet (in high-pT jet production) in each event to
define three regions of \eta-\phi space; toward, away, and transverse, where
\phi is the azimuthal scattering angle. For Drell-Yan production (excluding the
leptons) both the toward and transverse regions are very sensitive to the
underlying event. In high-pT jet production the transverse region is very
sensitive to the underlying event and is separated into a MAX and MIN
transverse region, which helps separate the hard component (initial and
final-state radiation) from the beam-beam remnant and multiple parton
interaction components of the scattering. The data are corrected to the
particle level to remove detector effects and are then compared with several
QCD Monte-Carlo models. The goal of this analysis is to provide data that can
be used to test and improve the QCD Monte-Carlo models of the underlying event
that are used to simulate hadron-hadron collisions.Comment: Submitted to Phys.Rev.
Measurement of the Production Cross Section and Search for Anomalous and Couplings in Collisions at TeV
This Letter describes the current most precise measurement of the boson
pair production cross section and most sensitive test of anomalous
and couplings in collisions at a center-of-mass energy of 1.96
TeV. The candidates are reconstructed from decays containing two charged
leptons and two neutrinos, where the charged leptons are either electrons or
muons. Using data collected by the CDF II detector from 3.6 fb of
integrated luminosity, a total of 654 candidate events are observed with an
expected background contribution of events. The measured total
cross section is pb, which is in good agreement
with the standard model prediction. The same data sample is used to place
constraints on anomalous and couplings.Comment: submitted to Phys. Rev. Let
Report from Working Group 3: Beyond the standard model physics at the HL-LHC and HE-LHC
This is the third out of five chapters of the final report [1] of the Workshop on Physics at HL-LHC, and perspectives on HE-LHC [2]. It is devoted to the study of the potential, in the search for Beyond the Standard Model (BSM) physics, of the High Luminosity (HL) phase of the LHC, defined as ab of data taken at a centre-of-mass energy of 14 TeV, and of a possible future upgrade, the High Energy (HE) LHC, defined as ab of data at a centre-of-mass energy of 27 TeV. We consider a large variety of new physics models, both in a simplified model fashion and in a more model-dependent one. A long list of contributions from the theory and experimental (ATLAS, CMS, LHCb) communities have been collected and merged together to give a complete, wide, and consistent view of future prospects for BSM physics at the considered colliders. On top of the usual standard candles, such as supersymmetric simplified models and resonances, considered for the evaluation of future collider potentials, this report contains results on dark matter and dark sectors, long lived particles, leptoquarks, sterile neutrinos, axion-like particles, heavy scalars, vector-like quarks, and more. Particular attention is placed, especially in the study of the HL-LHC prospects, to the detector upgrades, the assessment of the future systematic uncertainties, and new experimental techniques. The general conclusion is that the HL-LHC, on top of allowing to extend the present LHC mass and coupling reach by on most new physics scenarios, will also be able to constrain, and potentially discover, new physics that is presently unconstrained. Moreover, compared to the HL-LHC, the reach in most observables will, generally more than double at the HE-LHC, which may represent a good candidate future facility for a final test of TeV-scale new physics
Search for Technicolor Particles Produced in Association with a W Boson at CDF
submitted to Phys. Rev. LettWe present a search for the technicolor particles and in the process at a center of mass energy of . The search uses a data sample corresponding to approximately of integrated luminosity accumulated by the CDF II detector at the Fermilab Tevatron. The event signature we consider is and or depending on the charge. We select events with a single high- electron or muon, large missing transverse energy, and two jets. Jets corresponding to bottom quarks are identified with multiple -tagging algorithms. The observed number of events and the invariant mass distributions are consistent with the standard model background expectations, and we exclude a region at 95% confidence level in the - mass plane. As a result, a large fraction of the region - and - is excluded.We present a search for the technicolor particles ρT and πT in the process pp̅ →ρT→WπT at a center of mass energy of √s=1.96 TeV. The search uses a data sample corresponding to approximately 1.9 fb-1 of integrated luminosity accumulated by the CDF II detector at the Fermilab Tevatron. The event signature we consider is W→ℓν and πT→bb̅ , bc̅ or bu̅ depending on the πT charge. We select events with a single high-pT electron or muon, large missing transverse energy, and two jets. Jets corresponding to bottom quarks are identified with multiple b-tagging algorithms. The observed number of events and the invariant mass distributions are consistent with the standard model background expectations, and we exclude a region at 95% confidence level in the ρT-πT mass plane. As a result, a large fraction of the region m(ρT)=180–250 GeV/c2 and m(πT)=95–145 GeV/c2 is excluded.Peer reviewe
Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an
Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð¥with constraintsð ð 𥠥 ðandð´ð¥ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis
First Measurement of the b-jet Cross Section in Events with a W Boson in p-pbar Collisions at sqrt{s} = 1.96 TeV
8 pages, 2 figures. Slight change to abstract per PRL referee requests. A few additional citations as well per PRL referee request.The cross section for jets from b quarks produced with a W boson has been measured in ppbar collision data from 1.9/fb of integrated luminosity recorded by the CDF II detector at the Tevatron. The W+b-jets process poses a significant background in measurements of top quark production and prominent searches for the Higgs boson. We measure a b-jet cross section of 2.74 +- 0.27(stat.) +- 0.42(syst.) pb in association with a single flavor of leptonic W boson decay over a limited kinematic phase space. This measured result cannot be accommodated in several available theoretical predictions.The cross section for jets from b quarks produced with a W boson has been measured in pp̅ collision data from 1.9 fb-1 of integrated luminosity recorded by the CDF II detector at the Tevatron. The W+b-jets process poses a significant background in measurements of top quark production and prominent searches for the Higgs boson. We measure a b-jet cross section of 2.74±0.27(stat)±0.42(syst) pb in association with a single flavor of leptonic W boson decay over a limited kinematic phase space. This measured result cannot be accommodated in several available theoretical predictions.Peer reviewe
Search for Fermion-Pair Decays Q\Qbar \to (\t\Wmp)(\tbar\Wpm) in Same-Charge Dilepton Events
7 pages, 4 figures, for Phys. Rev. LettWe report the most restrictive direct limits on masses of fourth-generation down-type quarks , and quark-like composite fermions ( or ), decaying promptly to . We search for a significant excess of events with two same-charge leptons (, ), several hadronic jets, and missing transverse energy. An analysis of data from collisions with an integrated luminosity of 2.7 fb collected with the CDF II detector at Fermilab yields no evidence for such a signal, setting mass limits 338 and 365 at 95% confidence level.We report the most restrictive direct limits on masses of fourth-generation down-type quarks b′, and quarklike composite fermions (B or T5/3), decaying promptly to tW∓. We search for a significant excess of events with two same-charge leptons (e, μ), several hadronic jets, and missing transverse energy. An analysis of data from pp̅ collisions with an integrated luminosity of 2.7 fb-1 collected with the CDF II detector at Fermilab yields no evidence for such a signal, setting mass limits mb′, mB>338 GeV/c2 and mT5/3>365 GeV/c2 at 95% confidence level.Peer reviewe
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