High Transverse Momentum Physics at the Large Hadron Collider

This note summarizes many detailed physics studies done by the ATLAS and CMS Collaborations for the LHC, concentrating on processes involving the production of high mass states. These studies show that the LHC should be able to elucidate the mechanism of electroweak symmetry breaking and to study a variety of other topics related to physics at the TeV scale. In particular, a Higgs boson with couplings given by the Standard Model is observable in several channels over the full range of allowed masses. Its mass and some of its couplings will be determined. If supersymmetry is relevant to electroweak interactions, it will be discovered and the properties of many supersymmetric particles elucidated. Other new physics, such as the existence of massive gauge bosons and extra dimensions can be searched for extending existing limits by an order of magnitude or more.Comment: Authors listed are the editor

QCD-supression by Black Hole Production at the LHC

Possible consequences of the production of small black holes at the LHC for different scenarios with large extra dimensions are investigated. The effects from black hole production on some standard jet observables are examined, concentrating on the reduction of the QCD cross section. It is found that black hole production of partons interacting on a short enough distance indeed seem to generate a drastic drop in the QCD cross section. However from an experimental point of view this will in most cases be camouflaged by energetic radiation from the black holes

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内容摘要薪酬制度是企业人力资源管理的核心。它体现了企业人力资源价值的分配和人力资源管理理念。企业在设计新酬制度的过程中，必须在其经营战略的框架下，通过对其薪酬组成元素的优化配置，以整体薪酬制度的形式来发挥薪酬效能，以支持企业战略目标的实现和满足员工多元化的需求。企业营销人员薪酬制度问题，是营销管理中的一个重要课题，建立一套科学、有效的销售人员薪酬制度并非易事。世界上没有通用、固定不变的某种销售薪酬制度，它将随企业营销战略、模式、渠道，所提供的产品或服务性质，细分客户群和客户类型等的不同而存在差异。可以说，不同类型的销售人员、不同类型的企业、不同类型的市场，就有不同类型的薪酬制度。本文从薪酬的基...ABSTRACT Salary system is the core of human resource management for enterprise. It expresses the enterprise’s value distribution and management idea of human resource. When an enterprise initiates its salary system, it is very important for them to optimize the allocation of salary elements based on the enterprise’s operation strategy so as to maximize the efficiency of salary system by way ...学位：工商管理硕士院系专业：管理学院高级经理教育中心（EMBA项目）_管理经济学学号：X20031503

A high efficiency photon veto for the Light Dark Matter eXperiment

Fixed-target experiments using primary electron beams can be powerful discovery tools for light dark matter in the sub-GeV mass range. The Light Dark Matter eXperiment (LDMX) is designed to measure missing momentum in high-rate electron fixed-target reactions with beam energies of 4 GeV to 16 GeV. A prerequisite for achieving several important sensitivity milestones is the capability to efficiently reject backgrounds associated with few-GeV bremsstrahlung, by twelve orders of magnitude, while maintaining high efficiency for signal. The primary challenge arises from events with photo-nuclear reactions faking the missing-momentum property of a dark matter signal. We present a methodology developed for the LDMX detector concept that is capable of the required rejection. By employing a detailed Geant4-based model of the detector response, we demonstrate that the sampling calorimetry proposed for LDMX can achieve better than 10⁻¹³ rejection of few-GeV photons. This suggests that the luminosity-limited sensitivity of LDMX can be realized at 4 GeV and higher beam energies

A high efficiency photon veto for the Light Dark Matter eXperiment

Fixed-target experiments using primary electron beams can be powerful discovery tools for light dark matter in the sub-GeV mass range. The Light Dark Matter eXperiment (LDMX) is designed to measure missing momentum in high-rate electron fixed-target reactions with beam energies of 4 GeV to 16 GeV. A prerequisite for achieving several important sensitivity milestones is the capability to efficiently reject backgrounds associated with few-GeV bremsstrahlung, by twelve orders of magnitude, while maintaining high efficiency for signal. The primary challenge arises from events with photo-nuclear reactions faking the missing-momentum property of a dark matter signal. We present a methodology developed for the LDMX detector concept that is capable of the required rejection. By employing a detailed Geant4-based model of the detector response, we demonstrate that the sampling calorimetry proposed for LDMX can achieve better than 10⁻¹³ rejection of few-GeV photons. This suggests that the luminosity-limited sensitivity of LDMX can be realized at 4 GeV and higher beam energies

Photon-rejection Power of the Light Dark Matter eXperiment in an 8 GeV Beam

The Light Dark Matter eXperiment (LDMX) is an electron-beam fixed-target experiment designed to achieve comprehensive model independent sensitivity to dark matter particles in the sub-GeV mass region. An upgrade to the LCLS-II accelerator will increase the beam energy available to LDMX from 4 to 8 GeV. Using detailed GEANT4-based simulations, we investigate the effect of the increased beam energy on the capabilities to separate signal and background, and demonstrate that the veto methodology developed for 4 GeV successfully rejects photon-induced backgrounds for at least $2\times10^{14}$ electrons on target at 8 GeV.Comment: 28 pages, 20 figures; corrected author lis

Measurement of distributions sensitive to the underlying event in inclusive Z-boson production in pp collisions at √s = 7 TeV with the ATLAS detector

A measurement of charged-particle distributions sensitive to the properties of the underlying event is presented for an inclusive sample of events containing a TeX -boson, decaying to an electron or muon pair. The measurement is based on data collected using the ATLAS detector at the LHC in proton–proton collisions at a centre-of-mass energy of TeX TeV with an integrated luminosity of TeX fb TeX . Distributions of the charged particle multiplicity and of the charged particle transverse momentum are measured in regions of azimuthal angle defined with respect to the TeX -boson direction. The measured distributions are compared to similar distributions measured in jet events, and to the predictions of various Monte Carlo generators implementing different underlying event models

Measurement of the muon reconstruction performance of the ATLAS detector using 2011 and 2012 LHC proton–proton collision data

This paper presents the performance of the ATLAS muon reconstruction during the LHC run with pp collisions at √s = 7–8 TeV in 2011–2012, focusing mainly on data collected in 2012. Measurements of the reconstruction efficiency and of the momentum scale and resolution, based on large reference samples of J/ψ → μμ, Z → μμ and ϒ → μμ decays, are presented and compared to Monte Carlo simulations. Corrections to the simulation, to be used in physics analysis, are provided. Over most of the covered phase space (muon |η| < 2.7 and 5 ≲pT ≲pT 100 GeV) the efficiency is above 99% and is measured with per-mille precision. The momentum resolution ranges from 1.7% at central rapidity and for transverse momentum pT ≃ 10 GeV, to 4% at large rapidity and pT ≃ 100 GeV. The momentum scale is known with an uncertainty of 0.05% to 0.2% depending on rapidity. A method for the recovery of final state radiation from the muons is also presented

Search for pair and single production of new heavy quarks that decay to a Z boson and a third-generation quark in pp collisions at √s=8 TeV with the ATLAS detector

A search is presented for the production of new heavy quarks that decay to a Z boson and a third-generation Standard Model quark. In the case of a new charge +2/3 quark (T ), the decay targeted is T → Zt, while the decay targeted for a new charge −1/3 quark (B) is B → Zb. The search is performed with a dataset corresponding to 20.3 fb−1 of pp collisions at TeX TeV recorded in 2012 with the ATLAS detector at the CERN Large Hadron Collider. Selected events contain a high transverse momentum Z boson candidate reconstructed from a pair of oppositely charged same-flavor leptons (electrons or muons), and are analyzed in two channels defined by the absence or presence of a third lepton. Hadronic jets, in particular those with properties consistent with the decay of a b-hadron, are also required to be present in selected events. Different requirements are made on the jet activity in the event in order to enhance the sensitivity to either heavy quark pair production mediated by the strong interaction, or single production mediated by the electroweak interaction. No significant excess of events above the Standard Model expectation is observed, and lower limits are derived on the mass of vector-like T and B quarks under various branching ratio hypotheses, as well as upper limits on the magnitude of electroweak coupling parameters.publishedVersio