| Title▼ | Belle II Number▼ | Tags | Submit date▼ | Downloads |
|---|---|---|---|---|
|
Study of $B\rightarrow (\chi_{c1} \gamma) K$ DecayPublic
The thesis aims to perform a sensitivity study of the $B \to X(3823) K \pi$ in the Belle II data set. If $X(3823)$ is $\psi(1\,^3D_{2})$ state with $J^{PC}=2^{--}$, like $\chi_{c2}$ ($J^{PC}=2^{++}$), its branching fraction of three body decay mode $B \rightarrow (\chi_{c1}\gamma) K \pi$ will be higher than its two body decay mode $B \rightarrow (… |
BELLE2-MTHESIS-2023-027 | - | 2020-11-11 |
|
|
Study of 𝐵 → 𝜋^−ℓ^+𝜈_ℓ Decays Using Fully Reconstructed ϒ(4𝑆) → 𝐵 \bar 𝐵 Events at the Belle II ExperimentPublic
We present the results of a study of exclusively reconstructed 𝐵 → 𝜋^−ℓ^+𝜈_ℓ decays, where ℓ is an electron or a muon. Complementary 𝐵 meson is reconstructed using the Full Event Interpretation algorithm. We take a piece of MC as a data and using an independent second MC sample try to analyse the method and its implications. We then try to make an… |
BELLE2-MTHESIS-2021-070 | - | 2020-11-11 |
|
|
Search for the decay Bs0 → η' Xss̄ Using a Semi-Inclusive Method at the Belle ExperimentPublic
The decay Bs0 → η' Xss̄ is searched for at Belle, using Belle’s 121.4 fb − 1 integrated luminosity data sample, taken at Υ( 5S ) resonance. A semi- inclusive reconstruction method whereby the Xss̄ is reconstructed as a system of two kaons and up to four pions, with at most one neutral pion, is used. Using the η' sub-decay mode η' → η (→ γγ ) π + π −… |
BELLE2-PTHESIS-2021-003 | - | 2020-11-11 |
|
|
A Study for Improvements in Signal Readout and Background Rejection of Belle II Silicon Vertex DetectorPublic
The Belle II experiment at KEK, Tsukuba, Japan, is conducted to search for new physics beyond the Standard Model (SM) through the precise measurement of the SM parameter in the flavor physics. For this purpose, we measure e+e− collision events using the high luminosity accelerator SuperKEKB. To precisely measure the decay vertices, we locate the V… |
BELLE2-MTHESIS-2021-017 | - | 2020-11-11 |
|
|
Search for an invisible $Z^\prime$ in $\mu^{+}\mu^{-}$ plus missing energy events at Belle IIPublic
The Standard Model (SM) of particle physics has been proven by many experimental results to be a predictive theory and currently the best known description of the fundamental constituents of nature and their interactions. However, it cannot account for some known phenomena, such as the existence of dark matter, established by many astrophysical an… |
BELLE2-PTHESIS-2020-001 | - | 2020-11-11 |
|
|
Search for new physics in B0 radiative decays and measure of their lifetime with the Belle II experimentPublic
After the Big Bang matter and antimatter were present in equal amounts. Today, however, everything we see, is made almost entirely of matter. A fundamental ingredient to explain this asymmetry between matter and antimatter is the violation of the CP (Charge Parity) symmetry. CP violation has been observed but quantitatively not enough to explain t… |
BELLE2-PTHESIS-2021-001 | - | 2020-11-11 |
|
|
Development and performance study of particle identification using machine learning technique at the Belle II experiment (in Japanese)Public
SuperKEKB/Belle II実験では7 GeVと4 GeVに加速された電子・陽電子を衝突させることで高統計量のB中間子対等を生成し、終状態粒子の情報をもとに崩壊の様子を精密に測定することで標準理論の精密測定や新物理探索を行う。本実験では荷電粒子の識別を行う際に、チェレンコフ角やエネルギー損失などの測定が可能な6つの検出器の情報を用いる。現在各検出器から得られる尤度の積を指標として粒子識別を行なっている。しかしまだ期待通りの識別性能が出ておらず、例えば尤度計算の際に必要な検出器の応答モデルに問題がある可能性が存在する。そこで本研究ではそうした問題等によって現れる各検出器の尤度の相関を考慮することが可能な機械学習手法を導入することで、検出器の応答をより理解するとともに、粒子識別性能の向… |
BELLE2-MTHESIS-2021-009 | - | 2020-11-11 |
|
|
First charmless B decay reconstruction in Belle II dataPublic
This is an experimental particle physics thesis aimed at the first reconstruction of charmless decays of B mesons in Belle II data. Belle II is a detector designed to reconstruct billions of decays of heavy mesons and τ leptons from 10 GeV electron-positron collisions in search for indirect indications of non-Standard-Model physics. Decays of b qu… |
BELLE2-MTHESIS-2020-007 | - | 2020-11-11 |
|
|
Demonstrating learned particle decay reconstruction using Graph Neural Networks at BelleIIPublic
The clean environment within Belle II, with decay processes originating from non-composite electron-positron pairs, allows for the reconstruction of the entire collision event. Having precise information about the initial state kinematics gives a unique advantage to the Belle II experiment in that allows for direct measurements of decay processes … |
BELLE2-MTHESIS-2020-006 | - | 2020-11-11 |
|
|
B-Physics in Lattice QCD and at Belle IIPublic
Theory and experiment both have key roles to play in our understanding of the Universe. In flavour physics, semileptonic and leptonic decays of B mesons let us access CKM matrix elements, and anomalies in these decay processes offer tantalising hints of new physics. New measurements of these processes with improved statistical and systematic error… |
BELLE2-PTHESIS-2020-003 | - | 2020-11-11 |
|
|
Measurement of time-integrated CP asymmetry in D0->pipi and D0->KK with Belle II Monte Carlo dataPublic
It could be the key of the new physics to measure Time-integrated CP asymmetry(A_CP) of Charm particles. This is because the order of A_CP is small in Standard Model. Among many charm decay channels, Belle collaboration measured A_CP of D0->pipi channel and D0->KK using 976fb-1 experiment data whose result is A_CP^pipi = (+0.55+-0.36+-0.09)% and A… |
BELLE2-MTHESIS-2020-003 | - | 2020-11-11 |
|
|
Extending the Full Event Interpretation to the Υ(5S) ResonancePublic
The Full Event Interpretation is Belle II's algorithm to fully reconstruct B mesons in several thousand decay channels at the Y(4S) bottomonium resonance. This work presents the adaptation of this algorithm to B meson production at a higher center-of-mass energy, the Y(5S) resonance. The implemented changes are validated using converted data from … |
BELLE2-MTHESIS-2020-002 | - | 2020-11-11 |
|
|
Machine induced background study and simulation optimization at the SuperKEKB acceleratorPublic
In 2004 the idea of an upgrade of KEKB to a machine with an even higher instantaneous luminosity started to be developed, and culminated in 2019 with the start of operations of SuperKEKB and the Belle II detector. One big challenge for such a high luminosity collider is machine induced backgrounds, so it is necessary to study all possible counterm… |
BELLE2-PTHESIS-2023-012 | - | 2020-11-11 |
|
|
Belle II 実験のための光検出器HAPDを用いた ARICH検出器の性能評価Public
Belle II 実験は標準理論を越えた新物理探索を目的とする素粒子物理学実験である。高エネルギー加速器研究機構KEK のSuperKEKB 加速器を用いて電子・陽電子対をそれぞれ7GeV/c と4GeV/c まで加速し、衝突によりB・反B中間子対を大量に生成する。それらが崩壊して出てくる素粒子をBelle II 検出器によって精密測定し、B 中間子の崩壊過程や崩壊時間を測定する。崩壊過程の測定では崩壊後の粒子識別が非常に重要であり、特に荷電K 中間子と荷電 中間子は様々な物理解析において精度の高い識別が要求されており、実験の精度に大きく影響する。ARICH検出器はBelle II 検出器エンドキャップ部においてK= 識別を担うリングイメージ型のチェレンコフ検出器である。ARICH 検出器… |
BELLE2-MTHESIS-2021-026 | - | 2020-11-11 |
|
|
Search for an invisibly decaying $Z^{\prime}$ dark boson at Belle II in $e^+ e^- \to \mu^+ \mu^- (e^{\pm} \mu^{\mp})$ + missing energy final statesPublic
The Standard Model (SM) is a successful and highly predictive theory of fundamental particles and interactions. However, it cannot be considered as a complete description of nature due to the fact that many phenomena, including Dark Matter, are not accounted for. One of the simplest ways to extend the SM is by adding an extra $U(1)^{\prime}$ gaug… |
BELLE2-PTHESIS-2020-002 | - | 2020-11-11 |
|
|
Irradiation Burst Studies on Belle II PXD Module ComponentsPublic
The Belle II detector started recording collision data in spring 2019. During physics runs, unexpected irradiation burst events occurred, which exposed the inner detectors and especially the PXD (PiXel Detector) to unwanted levels of prompt irradiation. Dedicated measurement campaigns were carried out at the Mainz Microtron (MAMI), which aimed to … |
BELLE2-MTHESIS-2022-037 | - | 2020-11-11 |
|
|
Displaced track finding efficiency and detecting new long-lived particles at Belle IIPublic
There are numerous extensions to the Standard Model that introduce new particles that have long lifetimes, corresponding to a flight length of centimetres or more in a particle collider. No such particle has yet been found, with searches often being limited statistically. The high luminosity that the SuperKEKB collider provides the Belle II experi… |
BELLE2-MTHESIS-2022-023 | - | 2020-11-11 |
|
|
Feasibility study of dark-photon searches in the single photon plus missing events in e+e- collisions at Belle II. Public
We carried out the feasibility study of the dark-photon searches for events where only a single photon is detected, using signal and background Monte-Carlo simulation. The backgrounds are dominated by the radiative Bhabha and three-photon production processes. Signal sensitivities are studied by changing the requirements for the responses in the … |
BELLE2-MTHESIS-2022-016 | - | 2020-11-11 |
|
|
SEARCH FOR B → K (∗) ν ν̄ DECAYS IN BELLE IIPublic
The B → K (∗) ν ν̄ decay channel, never discovered to this day, is actively sought for in the Belle II experiment. Its branching fraction of the order of 10 −6 could be significantly skewed by new physics, which makes it a potential probe for physics beyond the Standard Model. During this internship, we simulated and analyzed pairs of B mesons prod… |
BELLE2-MTHESIS-2022-003 | - | 2020-11-11 |
|
|
Search for B → τν decay at the Belle II experimentPublic
This thesis project is divided into two parts. In the first part, the sensitivity of the Belle II experiment to the search for B → τ ν decays with a Monte Carlo simulated sample of 1 ab-1 is described. In the second part, it is studied the agreement of the MC simulation with data collected in 2019 corresponding to L = 8.86fb−1. |
BELLE2-MTHESIS-2023-009 | - | 2020-11-11 |
|