Vortex strings are topological solitons in field theories and appear in various systems, such as superconductor, neutron star, early universe and so on. We clarify the nature of vortex strings in the Abelian-Higgs-like model with a Coleman-Weinberg type Higgs potential, which is inspired by the argument of the naturalness problem in particle physics. This model has the gauge U(1) symmetry and the classical scale invariance. The model has no vortex string solution at the classical level, while quantum corrections spontaneously break the U(1) symmetry and stable vortex strings exist. The interaction between the two vortex strings is found to be very different from that of the Abelian-Higgs model with the conventional second- and fourth-order type potentials. Implications for particle physics and cosmology are also discussed.

In this talk, I want to motivate a possible way to realise time as an emergent concept. I will introduce a general fermionic system and demonstrate how a modular flow can be interpreted as a physical time flow. I will provide support for this interpretation using the thermofield double state together with the relations between various quantum chaos diagnostic quantities. I will explain how these concepts can be linked together and realise an emergence of time. I will end by discussing some limitations of our example.

The CDF collaboration recently announced the most precise measurement of the W-boson mass by using the proton-antiproton collision data at the Fermilab Tevatron. This data provides a significant inconsistency between the measured mass and the Standard Model prediction. In this talk, first, I will summarize the current circumstances of the W-boson mass measurements and the Standard Model prediction. Next, I will present several explanations of this anomaly by the new physics beyond the Standard Model. Finally, a model with the vector-like quark will be introduced, based on our recent work arXiv:2204.05962.

In the last year, the Fermilab experiment has reported their first result on the measurement of the muon anomalous magnetic moment (g-2). The result was consistent with the Brookhaven E821 experiment, and the deviation from the standard model prediction becomes 4.2sigma, which is planned to be revised soon. In this talk, we will overview the status and prospect of the theoretical side of the muon g-2. I will first review the standard model prediction and explain the issues explored today. Then, new physics interpretations will be discussed, especially focusing on the supersymmetric models.

A Narain CFT is a conformal field theory (CFT) that describes a compactified spacetime. On the other hand, an error-correcting code is a concept in information theory for transmitting information correctly in spite of errors. In this talk, I will discuss the relation between Narain CFTs and error-correcting codes on finite fields through lattices. Using this correspondence, we can consider the spectrum and the symmetries of the CFT in the language of the code. In particular, the spectral gap of the CFT and the error correction capability of the code are roughly proportional, which helps to find CFTs with large spectral gaps.

Axion (or axion-like particle) is a prominent candidate of light dark matter (DM). It emerged as the pseudo Nambu-Goldstone boson originated from the breaking of global U(1) symmetry. If the mass scale is keV, axion usually suffers from the severe constraint from the X-ray bounds. However, a fascinating axion, which can evade such a severe constraint, was proposed as an anomaly-free axion. In this talk, I will discuss a three Higgs doublet model (3HDM) as a UV complete model where the anomaly-free axion is embodied. I will show the synergy between the anomaly-free axion and the heavy Higgs bosons predicted in this concrete model.

Symmetry protected topological (SPT) phases are one of the simplest, yet nontrivial, gapped systems that go beyond the Landau paradigm. In this work, we study the notion of SPT for critical systems, namely, symmetry protected topological criticality (SPTC). We discuss a systematic way of constructing a large class of SPTCs using decorated defect construction, study the physical observables that characterize the nontrivial topological signatures of SPTCs, and discuss the stability under symmetric perturbations. Our exploration of SPTC is mainly based on several previous studies of gapless SPT: gapless symmetry protected topological order, symmetry enriched quantum criticality and intrinsically gapless topological phases. We partially reinterpret these previous studies in terms of decorated defect construction, and discuss their generalizations.

We present a class of dS/CFT correspondence between two-dimensional CFTs and three-dimensional de Sitter spaces. We argue that such a CFT includes an SU(2) WZW model in the critical level limit k → −2, which corresponds to the classical gravity limit. We can generalize this dS/CFT by considering the SU(N) WZW model in the critical level limit k →−N, dual to the higher spin gravity on a three-dimensional de Sitter space. We confirm that under this proposed duality the classical partition function in the gravity side can be reproduced from CFT calculations.

I will talk about some phenomenological aspects of the two Higgs doublet model(2HDM). The 2HDM can explain the muon anomalous magnetic moment with a light pseudoscalar. I will discuss the prospect of discovering such particles at the lepton collider like ILC. Then I will discuss how an extension of 2HDM can connect neutrino mass and muon anomalous magnetic moment.

The Nuclear Incompressibility parameter is one of three important components characterizing the nuclear equation of state (EOS). It has crucial bearing on diverse nuclear and astrophysical phenomena, including radii of neutron stars, strength of supernova collapse, emission of neutrinos in supernova explosions, and collective flow in medium- and high-energy nuclear collisions. In this talk I will review current status of the research on direct experimental determination of nuclear incompressibility via the compressional-mode giant resonances. In particular, measurements on a series of Sn and Cd isotopes have provided an "experimental" value for the asymmetry term of the nuclear incompressibility; this term is important for the EOS of neutron stars. We also find that the GMR centroid energies of the in both Sn and Cd isotopes are significantly lower than the theoretical predictions, pointing to the possible role of superfluidity in nuclear incompressibility.
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IPC intensive lecture will be also given online by Prof. Umesh Garg during Feb 1-4.
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問い合わせ先：川畑　貴裕　（理学研究科物理学専攻）