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A Study Of Data/Monte Carlo Agreement In Charmed Baryon Decays At Belle Ii, Kaitlyn Thurmond

Honors Theses

The Belle II experiment at the SuperKEKB electron-positron accelerator facility in Tsukuba, Japan has a primary goal of searching for new physics beyond the Standard Model of particle physics. Extremely precise measurements of particle decays will be compared with Standard Model predictions in order to expose the presence of new particles and interactions. These measurements are prepared using simulated samples to avoid potential biases when studying the data. The Belle II collaboration produces two types of simulated samples for this purpose. One is produced with consistent calibration payloads and another with payloads calibrated as a function of data taking. This …

An Analysis Of Detection Asymmetry Using Baryon Decays In Belle Ii, Matthew Mestayer

Honors Theses

The purpose of this study was to determine the detection asymmetry of the Belle II detector using decays of two common baryons, Λ⁰ → ��π^- and Σ⁺ → ��π⁰. A Monte Carlo simulation of both decays was used to determine the validity of signal isolation criteria. These criteria were then applied to the Belle II data, allowing for a comparison of the detection asymmetry in the data relative to the simulation. The results show a moderate detection asymmetry when using the Λ⁰ → ��π^- decay, particularly for forward-going baryons. For the Σ^{+ …}

Study Of Missing Mass Background In The Clas12 Detector, Jessie Hess, Gerard P. Gilfoyle, Lamya Baashen

Honors Theses

At Jefferson Lab we use the CLAS12 detector to measure the neutron magnetic form factor. An accurate measurement of the CLAS12 neutron detection efficiency (NDE) is required. We use the nuclear reaction ���� → ��′��+�� as a source of tagged neutrons and obtain the NDE from the ratio of expected neutrons to detected ones. We assume the final state consists of ��′��+�� only, use the ��′��+ information to predict the neutron's position(expected) and then search for that neutron(detected). We select neutrons with the missing mass (MM) technique. We use simulation to validate our methods. We simulated events with the Monte-Carlo …

New Physics In The Age Of Precision Cosmology, Vivian I. Sabla

Dartmouth College Ph.D Dissertations

The Lambda-cold dark matter (LCDM) model has become the standard model of cosmology because of its ability to reproduce a vast array of cosmological observations, from the earliest moments of our Universe, to the current period of accelerated expansion, which it does with great accuracy. However, the success of this model only distracts from its inherent flaws and ambiguities. LCDM is purely phenomenological, providing no physical explanation for the nature of dark matter, responsible for the formation and evolution of large-scale structure, and giving an inconclusive explanation for dark energy, which drives the current period of accelerated expansion.

Furthermore, cracks …

Symbolic Computation Of Squared Amplitudes In High Energy Physics With Machine Learning, Abdulhakim Alnuqaydan

Theses and Dissertations--Physics and Astronomy

The calculation of particle interaction squared amplitudes is a key step in the calculation of cross sections in high-energy physics. These complex calculations are currently performed using domain-specific symbolic algebra tools, where the computational time escalates rapidly with an increase in the number of loops and final state particles. This dissertation introduces an innovative approach: employing a transformer-based sequence-to-sequence model capable of accurately predicting squared amplitudes of Standard Model processes up to one-loop order when trained on symbolic sequence pairs. The primary objective of this work is to significantly reduce the computational time and, more importantly, develop a model that …

Improved Constraints On The Standard Model Higgs Self-Interaction Using A Search For Hh → 4b Via The Vector-Boson Fusion Production Mode At √S = 13 Tev In 126 Fb^-1 Of Data Collected By The Atlas Experiment, Christopher Milke

Physics Theses and Dissertations

A search for di-Higgs production via the Vector Boson Fusion mechanism decaying to 4 bottom quarks is performed using 126 fb−1 of data from Run 2 of ATLAS at √s = 13 TeV. The search was performed in the non-resonant regime, finding an upper bound on the production cross-section for the Standard Model VBF→HH→4b of about 200 times the Standard Model. Constraints are placed on both the HHVV coupling (which determines the W/Z-higgs four-point interaction strength) and HHH Higgs self-coupling scale factors at 95% confidence. The HHVV coupling scaling factor (κ2V ) is constrained to an observed interval between 0.09 …

A Performance Analysis Of The Belle Ii Detector, John Stacy

Honors Theses

The Belle II experiment has recently (2018) started data taking at the SuperKEKB electron-positron collider in Tsukuba, Japan. Detector performance studies are necessary to understand early data and prepare for more complex analyses. This study of the proton detection efficiency of the Belle II detector compares real and simulated data to find discrepancies with the intention to provide useful information for detector and calibration experts to better gauge detector performance. It also attempts to improve the characterization of proton identification efficiency at low momenta, which performs poorly under the current fitting model. This helps analysts exploring final states that include …

Monte Carlo Study Of Lepton Flavor Universality Violation In B Decays With Belle Ii Simulation, Sakul Mahat

Honors Theses

Belle II, the first super B-Factory experiment, is designed to make precise measurements of weak interaction parameters and search for New Physics beyond the Standard Model of particle physics. The Standard Model of particle physics is a theory that classifies all known elementary particles and describes three of the four known fundamental forces in the universe. Physics beyond the Standard Model that addresses the theoretical developments needed to explain the deficiencies in the Standard Model is often referred to as New Physics. One of the assumptions of the Standard Model is that the couplings of particles that mediate the weak …

Fast Statistical Methods For The Global Qcd Analysis Of The Proton Structure, Xiaoxian Jing

Physics Theses and Dissertations

Parton distribution functions (PDFs) quantify probabilities to find partons (quarks and gluons) in a hadron as a function of the fraction x of the hadron’s momentum carried by the parton at a given energy scale. PDFs play a critical role in precision tests of the Standard Model in Higgs boson production and other electroweak processes at the Large Hadron Collider (LHC), and in searches for physics beyond the Standard Model. PDFs are obtained by the global QCD analysis, which fits theoretical predictions to experimental measurements. PDF fitting and post-analysis are computationally intensive. This dissertation discusses fast statistical methods for the …

Constraints On Parton Distribution Functions Imposed By Hadronic Experiments, Boting Wang

Physics Theses and Dissertations

The theoretical uncertainties of the Large Hadron Collider (LHC) observables are decreasing with the increasing statistics of the LHC experiments, and it is becoming more and more important to reduce the uncertainties in the knowledge of the nucleon structure. The latest LHC high-energy experiments, future experimental proposals, and computational tools are expected to enhance the knowledge of the nucleon structure. However, the global analysis that assesses their impact on Parton Distribution Functions (PDFs) knowledge is computationally expensive due to the corresponding large size of data. I developed a new approach that can make a quick preliminary evaluation to help the …

A Search For Boosted Low Mass Resonances Decaying To The Bb̅ Final State And Produced In Association With A Jet At √S = 13 Tev With The Atlas Detector, Matthew Feickert

Physics Theses and Dissertations

A search in the high momentum regime for new resonances, produced in association with a jet, decaying into a pair of bottom quarks is presented using an integrated luminosity of 80.5 fb^-1 of proton-proton collisions at center-of-mass energy √s = 13 TeV recorded by the ATLAS detector at the Large Hadron Collider. The search was performed for low mass resonances, including the Standard Model Higgs boson and leptophobic Z' dark matter mediators, in the mass range of 100 GeV to 200 GeV. For the Standard Model Higgs boson, the observed signal strength is μH = 5.8 ± 3.1 (stat.) …

Massive Elementary Particles In The Standard Model And Its Supersymmetric Triplet Higgs Extension, Keping Xie

Physics Theses and Dissertations

In this dissertation, we focus on massive elementary particles in the Standard Model and its supersymmetric triplet Higgs extension.

In the first part, we start with a review of electroweak (EW) sector in the Standard Model. Motivated by nonzero neutrino masses, we consider triplet scalars in addition to the Standard Model. The vacuum expectation values of scalar triplets are strongly constrained by the $\rho$ parameter, extracted from electroweak precision measurements. Therefore, we introduce a custodial symmetry to weaken this constraint and obtain the well-known Georgi-Machacek (GM) Model. The GM model still requires fine-tuning to satisfy the $\rho$ parameter constraint. It …

The Impact Of Ppb W/Z Lhc Data On Ncteq15 Parton Distribution Functions With An Emphasis On Refitting The Ncteq15 Npdf Set, Eric Godat

Physics Theses and Dissertations

As the LHC experiments increase their statistics and reduce their systematics, it is in- creasingly important to reduce the theoretical uncertainties so we can perform precision com- parisons. The parton distribution functions (PDFs) which describe the hadronic structure of protons and nuclei are the critical link between the experimental data and the proposed theoretical models; hence, a better understanding of the PDFs is essential for improved pre- dictions. Nuclear PDFs, in particular, have proven valuable in this regard, especially for flavor differentiation. I introduce ”nCTEQ+LHC,” the first PDF set fit using the nCTEQ formalism to include data from the LHC. …

Muon-Neutrino Electron Elastic Scattering And A Search For The Muon-Neutrino Magnetic Moment In The Nova Near Detector, Biao Wang

Physics Theses and Dissertations

We use the NOvA near detector and the NuMI beam at Fermilab to study the neutrino-electron elastic scattering and the muon neutrino magnetic process beyond the Standard Model physics. The particle identifications of neutrino on electron elastic scattering are trained by using the multi-layer neural networks. This thesis provides a general discussion of this technique and shows a good agreement between data and MC for the neutrino-electron elastic weak scattering. By using 3.62e20 POT dataset in the NOvA near detector, we find 1.58e-9 Bohr magneton as the 90% C.L. upper limit. We also find a sensitivity of 8e-10 Bohr magneton …

Observing Orbital Angular Momentum Transfer From Electron Vortex Beams To Matter, Hannah Devyldere

Senior Theses

It is possible to produce electron beams with non-zero orbital angular momentum. Such beams, known as electron vortex beams, are theoretically able to transfer their orbital angular momenta to matter, causing the matter to rotate. Nanoparticles in an aqueous solution were observed with an electron vortex beam to detect the transfer of orbital angular momentum in a low-friction environment. Observing the transfer of orbital angular momentum to particles in solution is difficult due to the necessity of imaging the particles through a liquid and the random movement of particles in the solution. Thus, orbital angular momentum transfer to matter could …

Correction To Luminosity Measurement For The Pixel Luminosity Telescope At Cms, Krishna Thapa

Masters Theses

The search for and detailed study of new particles and forces with the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC) of CERN is fundamentally dependent on the precise measurement of the rate at which proton-proton collisions produce any particles, the so-called luminosity. Therefore, a new detector, the Pixel Luminosity Telescope (PLT), dedicated to measure the luminosity at high precision was added to the CMS experiment in 2015. It measures the inclusive charged particle production from each collision of proton bunches in the LHC. Additional charged particles which are observed by the instrument but produced from sources …

Solar Modulation Of The Cosmic Ray Intensity And The Measurement Of The Cerenkov Reemission In Nova’S Liquid Scintillator, Philip James Mason

Doctoral Dissertations

The NOνA (NuMI Off-axis electron neutrino Appearance) experiment is a long baseline neutrino oscillation experiment at Fermi National Accelerator Laboratory. Its purpose is to observe the oscillation of ν_μ (muon neutrino) to ν_e (electron neutrino) and to investigate the neutrino mass hierarchy and CP violation in the neutrino sector. Two detectors have been built for this purpose, a Near Detector 300 feet underground at Fermilab, and a Far Detector, on the surface at Ash River, Minnesota.

The completion of NOνA’s Far Detector in October 2014 enabled not only the recent measurement of neutrino oscillations, but an array of …

Measurement Of The Prompt Double J/Psi Production Cross Section In Pp Collisions At Sqrt(S) = 7 Tev, Andrew David York

Doctoral Dissertations

The simultaneous production of two J/psi mesons has been significantly observed in proton-proton collisions at a center-of-mass energy of 7 TeV with the CMS detector. The two J/psi mesons are fully reconstructed in their decay to muons. The signal yield is extracted with an extended maximum likelihood fit based on four event variables. A method was developed to correct for detector acceptances and efficiencies based on the measured momenta of the J/psi and their decay muons to maintain the least model dependence possible.

The measurement is performed in an acceptance region defined by the individual J/psi transverse momentum and rapidity. …