Fake Missing Transverse Energy from Calorimeter Effects

Calorimeter-Based Triggers at the ATLAS Detector for Searches for Supersymmetry in Zero-Lepton Final States

This thesis consists of three closely related parts. An analysis of data recorded by the ATLAS detector in 2010 in proton-proton collisions at a center-of-mass energy of 7 TeV with an integrated luminosity of 33.4/pb is performed, searching for supersymmetric final states containing jets and missing transverse energy and no electrons or muons (zero-lepton channel). No excess over the Standard Model background expectation is observed. Using the CLs and PLR methods, exclusion limits are set in two different supergravity models. These considerably extend the excluded parameter ranges from earlier…

Characterisation and performance of the PADME electromagnetic calorimeter

The PADME experiment at the LNF Beam Test Facility searches for dark photons produced in the annihilation of positrons with the electrons of a fix target. The strategy is to look for the reaction $e^{+}+e^{-}\rightarrow γ+A'$, where $A'$ is the dark photon, which cannot be observed directly or via its decay products. The electromagnetic calorimeter plays a key role in the experiment by measuring the energy and position of the final-state $γ$. The missing four-momentum carried away by the $A'$ can be evaluated from this information and the particle mass inferred. This paper presents the design,…

利用图神经网络进行强子聚类及减少Belle~II电磁量能器的束流背景

Using Graph Neural Networks for hadronic clustering and to reduce beam background in the Belle~II electromagnetic calorimeter

本文提出利用图神经网络解决Belle~II电磁量能器中强子聚类和减少背景挑战，通过改进的图结构学习提升能量分辨率和粒子识别能力。

Jets and Missing Transverse Energy Reconstruction with CMS

We report on the current simulation studies regarding the reconstruction of Jets and Missing Transverse Energy (MET) with the CMS detector at the CERN proton-proton LHC accelerator. The performance of various jet algorithms is compared, when using calorimeter energy deposits as inputs to the algorithm. The plan for obtaining jet energy corrections is outlined and data-driven correction methods are described. Finally, the performance of MET reconstruction is summarized.

Searches for New Physics in Events with a photon and a missing energy at CDF Run II

The addition of the EMTiming system installed to provide the time measurements of the electromagnetic calorimeter signals has significantly increased the sensitivity of CDF to events with a photon and a missing energy. Here I review recent searches in this signature performed by CDF using data from proton-antiproton collisions at the center of mass energy of 1.96 TeV. They provide new constraints on models with large extra dimensions and with gauge mediated supersymmetry breaking.

利用电磁量能器作为目标进行早期暗物质搜索的灵敏度研究

Sensitivity of an Early Dark Matter Search using the Electromagnetic Calorimeter as a Target for the Light Dark Matter eXperiment

LDMX实验通过电磁量能器作为主动靶，研究轻暗物质候选粒子的灵敏度，探索低质量暗物质的相互作用强度范围。

Performance of missing transverse momentum reconstruction with the ATLAS detector using proton-proton collisions at $\sqrt{s}$ = 13 TeV

The performance of the missing transverse momentum (E$_{T}^{miss}$) reconstruction with the ATLAS detector is evaluated using data collected in proton-proton collisions at the LHC at a center-of-mass energy of 13 TeV in 2015. To reconstruct E$_{T}^{miss}$, fully calibrated electrons, muons, photons, hadronically decaying $τ$-leptons, and jets reconstructed from calorimeter energy deposits and charged-particle tracks are used. These are combined with the soft hadronic activity measured by reconstructed charged-particle tracks not associated with the hard objects. Possible double counting of con…

Probabilistic Particle Flow Algorithm for High Occupancy Environment

Algorithms based on the particle flow approach are becoming increasingly utilized in collider experiments due to their superior jet energy and missing energy resolution compared to the traditional calorimeter-based measurements. Such methods have been shown to work well in environments with low occupancy of particles per unit of calorimeter granularity. However, at higher instantaneous luminosity or in detectors with coarse calorimeter segmentation, the overlaps of calorimeter energy deposits from charged and neutral particles significantly complicate particle energy reconstruction, reducing t…

Search for long-lived particles in events with photons and missing energy in proton-proton collisions at sqrt(s) = 7 TeV

Results are presented from a search for long-lived neutralinos decaying into a photon and an invisible particle, a signature associated with gauge-mediated supersymmetry breaking in supersymmetric models. The analysis is based on a 4.9 inverse femtobarn sample of proton-proton collisions at sqrt(s) = 7 TeV, collected with the CMS detector at the LHC. The missing transverse energy and the time of arrival of the photon at the electromagnetic calorimeter are used to search for an excess of events over the expected background. No significant excess is observed, and lower limits at the 95% confiden…

一种灵活高效的缺失横动量重建方法

A flexible and efficient approach for missing transverse momentum reconstruction

针对强子对撞机缺失横动量高精度计算的挑战，提出一种可适配任意重建对象选择标准的高效重建方法，含堆积抑制等模块，已助力ATLAS合作组优化多轮实验分析并支持未来研究。

Top-quark mass measurement in events with jets and missing transverse energy using the full CDF data set

We present a measurement of the top-quark mass using the full data set of Tevatron $\sqrt{s} = 1.96$ TeV proton-antiproton collisions recorded by the CDF II detector, corresponding to an integrated luminosity of \invfb{8.7}. The analysis uses events with one semileptonic $t$ or $\bar{t}$ decay, but without detection of the electron or muon. We select events with significant missing transverse energy and multiple jets. We veto events containing identified electrons or muons. We obtain distributions of the top-quark masses and the invariant mass of the two jets from $W$-boson decays from data an…

Search for long-lived particles using nonprompt jets and missing transverse momentum with proton-proton collisions at $\sqrt{s} =$ 13 TeV

A search for long-lived particles decaying to displaced, nonprompt jets and missing transverse momentum is presented. The data sample corresponds to an integrated luminosity of 137 fb$^{-1}$ of proton-proton collisions at a center-of-mass energy of 13 TeV collected by the CMS experiment at the CERN LHC in 2016-2018. Candidate signal events containing nonprompt jets are identified using the timing capabilities of the CMS electromagnetic calorimeter. The results of the search are consistent with the background prediction and are interpreted using a gauge-mediated supersymmetry breaking reference…

Search for non-pointing and delayed photons in the diphoton and missing transverse momentum final state in 8 TeV $pp$ collisions at the LHC using the ATLAS detector

A search has been performed, using the full 20.3 fb$^{-1}$ data sample of 8 TeV proton--proton collisions collected in 2012 with the ATLAS detector at the LHC, for photons originating from a displaced vertex due to the decay of a neutral long-lived particle into a photon and an invisible particle. The analysis investigates the diphoton plus missing transverse momentum final state, and is therefore most sensitive to pair-production of long-lived particles. The analysis technique exploits the capabilities of the ATLAS electromagnetic calorimeter to make precise measurements of the flight directi…

用于GeV中微子物理的液态氩时间投影室自补偿光量热法

Self-compensating Light Calorimetry with Liquid Argon Time Projection Chamber for GeV Neutrino Physics

本研究发现液态氩时间投影室（LArTPC）因复合发光效应可作为自补偿光量热仪，通过案例验证其在宽漂移电场范围内实现电子与强子响应比的良好补偿，为GeV中微子能量重建提供补充方法并提出非均匀光收集的解决方案。

Performance of algorithms that reconstruct missing transverse momentum in $\sqrt{s}=$ 8 TeV proton-proton collisions in the ATLAS detector

The reconstruction and calibration algorithms used to calculate missing transverse momentum ($E_{\rm T}^{\rm miss}$) with the ATLAS detector exploit energy deposits in the calorimeter and tracks reconstructed in the inner detector as well as the muon spectrometer. Various strategies are used to suppress effects arising from additional proton-proton interactions, called pileup, concurrent with the hard-scatter processes. Tracking information is used to distinguish contributions from the pileup interactions using their vertex separation along the beam axis. The performance of the $E_{\rm T}^{\rm…

\sqrt{s}_min: a global inclusive variable for determining the mass scale of new physics in events with missing energy at hadron colliders

We propose a new global and fully inclusive variable \sqrt{s}_{min} for determining the mass scale of new particles in events with missing energy at hadron colliders. We define \sqrt{s}_{min} as the minimum center-of-mass parton level energy consistent with the measured values of the total calorimeter energy E and the total visible momentum \vec{P}. We prove that for an arbitrary event, \sqrt{s}_{min} is simply given by the formula \sqrt{s}_{min}=\sqrt{E^2-P_z^2}+\sqrt{\met^2+M_{inv}^2}, where M_{inv} is the total mass of all invisible particles produced in the event. We use t\bar{t} productio…

在NA64实验中利用CERN SPS高能μ子束对μ子 $g-2$ 和轻质量暗物质解释的探索

Exploration of the Muon $g-2$ and Light Dark Matter explanations in NA64 with the CERN SPS high energy muon beam

本研究在NA64实验中利用160 GeV/c高能μ子束和缺失能量技术寻找 $Z'$ ($L_μ-L_τ$) 矢量玻色子，未观察到信号事件，从而对可能解释μ子 $g-2$ 反常及热暗物质遗迹丰度的参数空间设定了新限制，为探索暗物质铺平了道路。