Perturbative series in Quantum Field Theory (QFT) is typically divergent. While there is a standard way to resum divergent series called Borel resummation, it is expected that naive Borel resummation does not work in many QFTs including QCD. Resurgence is often used to cure this kind of situation both in physics and mathematics. In my lecture, I will begin with general expectation on...
Perturbative series in Quantum Field Theory (QFT) is typically divergent. While there is a standard way to resum divergent series called Borel resummation, it is expected that naive Borel resummation does not work in many QFTs including QCD. Resurgence is often used to cure this kind of situation both in physics and mathematics. In my lecture, I will begin with general expectation on...
Part 1
General introduction: Why do we need new physics beyond the SM?
General introduction: processes in e+e- as a function of energy; run plan of the ILC
Higgs boson: SM predictions for the decay rates and properties -- and, brief review of LHC measurements
Higgs boson: BSM effects on the Higgs couplings
Higgs boson: aspects of the experimental study in e+e-
Higgs boson: ...
Future lepton colliders are now intensively discussed around the world, and we have so far four proposals of the colliders; one from Asia (ILC and CEPC) and the other from Europe (FCC-ee and CLIC). The main goal of the colliders at the first stage (s1/2 = 240-250 GeV) is to precisely measure known Higgs couplings to tackle the problem of the electroweak symmetry breaking. On the other hand, it...
We revisit the Higgs-to-invisible decay ratio in Higgs-portal dark matter models. The Higgs-to-invisible decay searches are powerful probes of the models with increasing sensitivity in upcoming colliders. Close to the mass threshold of a Higgs decay into a pair of DM particles, the coupling value is expected to be very small in order to be compatible with the observed value of the thermal...
Sphaleron is a non-perturbative solution of electroweak gauge theories, which is crucially important for various scenarios of baryogenesis. In many of new physics models, the deviation in the sphaleron energy from the standard-model prediction is proportional to that in the triple Higgs boson coupling with opposite signs. This interesting relation would be useful to determine the sphaleron...
The discrepancy between the measured value and the Standard Model prediction of the muon anomalous magnetic moment is one of the most important issues in the particle physics. It is known that introducing a mediator boson X with the μτ lepton flavor violating (LFV) couplings is one good solution to explain the discrepancy, due to the τ mass enhancement in the one-loop correction. We study the...
A bit of Statistics
Precision: Jets, Higher-order corrections, more kinematics, and machine learning
Long-Lived Particles
Future hadron colliders (physics)
I will introduce the basic concepts of hadron collider physics in the first part of the lecture and discuss a few advanced topics in the second part of the lecture. The goal is to let the audience get familiar with the key...
We demonstrate that the classification of boosted, hadronically-decaying weak gauge bosons can be significantly improved over traditional cut-based and BDT-based methods by using deep learning and the jet charge variable. We construct binary taggers for W+ vs. W− and Z vs. W discrimination, as well as an overall ternary classifier for W+/W−/Z discrimination. We construct both ordinary and new...
Information deformation and loss in jet clustering are one of the major limitations for precisely measuring hadronic events at future e−e+ colliders. Because of their dominance in data, the measurements of such events are crucial for advancing the precision frontier of Higgs and electroweak physics in the next decades. In a recent arXiv paper (https://arxiv.org/pdf/2004.15013.pdf), the speaker...
A Higgsino-like particle is an attractive candidate for the WIMP dark matter. Thanks to the electroweak interaction, the production cross section of the Higgsino at the LHC is rather high. However, the huge Standard Model background prevents the Higgsino discovery, and the present LHC sensitivity can be even worse than the LEP result in some parameter region. In this talk, I discuss a new...
We study displaced vertex signatures of long-lived particles (LLPs) from exotic Higgs decays in the context of a Higgs-portal model and a neutral-naturalness model at the circular electron positron collider (CEPC) and future circular collider e+ e− (FCC-ee). Such two models feature two representative mass ranges for LLPs, which show very different behavior in their decay signatures. The...
Direct search of dark matter is expanding its search phase space. This lecture will cover the concepts, current status, and prospects of the dark matter direct searches including related topics.
Stars can be powerful laboratories to constrain the properties of low-mass particles such as neutrinos, axions, dark photons, low-mass dark-matter candidates, and others. This lecture will mainly focus on the back-reaction on stellar properties caused by the emission of new particles, so we will explain some of the basics of stellar evolution theory. We will also review some old and new limits...
In extensions of the Standard Model of particle physics, this could have been a first order phase transition, at about 10 picoseconds after the Big Bang. I will discuss the dynamics of the transition, the characteristic spectrum of gravitational radiation, and the prospects for observing the radiation at the future space-based gravitational wave detector LISA.
I will discuss the motivations for physics beyond the Standard Model below the Fermi scale, resulting in the existence of feebly interacting long-lived particles. The experimental prospects to search for these particles will be outlined.
Computation of QCD processes is always hard. The use of lattice QCD is limited to low-lying hadronic (often single-particle) states, so that only exclusive processes can be computed. Perturbation theory, plus operator product expansion, is used for high-energy processes for which the final states are not specified, or summed over all possible states, i.e. inclusive processes. There are...
I will provide a review of the theoretical basis of predictions for exclusive b -> s mu mu processes within the Standard Model and beyond. I will then discuss how present phenomenological studies of these decays are carried out, what improvements are forthcoming, and how the results should be interpreted.
