Junsei Tokuda, Ibs
Swampland program from amplitudes: gravitational positivity bounds
It is interesting if there exist non-trivial relations between ultraviolet complete quantum gravity and its low energy effective field theories (EFTs). Such relations are so-called swampland conditions. In this talk, we will develop a method to derive swampland conditions by extending so-called S-matrix positivity bounds to gravitational context. In our formulation, several working assumptions on quantum gravity S-matrix such as unitarity and the Reggeization of graviton exchange are imposed. We will then discuss the implications of positivity bounds on gravitational EFTs. First, we will demonstrate that our bounds are indeed satisfied in the Standard Model. Next, we will show that our bounds provide strong constraints on dark photon models which can be tested against on-going future experiments. This implies the possibility of probing quantum gravity from low-energy observables and the phenomenological importance of studying the properties of quantum gravity S-matrix.
Kyohei Mukaida, KEK
[QCD theory Seminar] Chiral asymmetry in the early Universe
Since the SM model is a chiral theory, asymmetries in matter generically result in chiral asymmetries. Nevertheless, the effect of the primordial chiral asymmetry is often neglected in the study of the early Universe because the baryon asymmetry is tiny. In this talk, I will discuss some examples where the chiral asymmetry plays essential roles, in particular in the context of baryogenesis.
KEK 素核研物構研 連携研究会
素粒子，原子核，宇宙，物性物理は，全く異なるスケールを対象と しているが，これらはすべて多体系の物理であり，相転移や対称性の 自発的破れといった様々な共通した概念や手法が見られる．一方で 分野の細分化により，それぞれの分野で独立に発展している概念や 手法が存在する．本研究会は，これらの分野の理論，実験の研究者が 一同に集まりそれぞれの分野で発展している話題を共有し，アイデアを 出し合うことでそれぞれの分野の発展および新しい科学の創出を目指します．
小野 寛太, 大阪大学
Hidenori Fukaya, Osaka University
Curved domain-wall fermion and its anomaly inflow
We consider a fermion system on a square lattice, where a curved domain-wall is assigned to the mass term. In a similar way to the standard flat domain-wall fermion, chiral edge modes appear at the wall. These edge-localized modes feel gravity, through the induced spin connection or metric due to the Einstein’s equivalence principle.
In the cases of circle $S^1$ and sphere $S^2$ domain-walls embedded into higher dimensional square lattices of one dimension higher, we numerically confirm the existence of the edge-localized modes and the effect of gravity encoded in the spectrum. With $U(1)$ link variables, we also find a good consistency to the anomaly inflow described by the Atiyah-Patodi-Singer index theorem in the continuum theory. This talk is based on a work with Shoto Aoki, https://arxiv.org/abs/2203.03782 and some preliminary results.
David J.E. Marsh, King's College London
[JpDe Joint Seminar] Axion Miniclusters: Recent Progress and Open Problems
If the Peccei Quinn symmetry is broken after inflaiton, then axions are produced by the decay of topological defects. This scenario is attractive, since the axion mass is in principle predictable from the relic density, and favours the range ~0.1-10 meV. Miniclusters offer a route to probe this scenario astrophysically. Miniclusters are formed from the overdensities in the axion field left over after the topological defects decay. I will describe recent efforts to understand the mass distribution and density profiles of miniclusters, using theory and simulation. I will also describe efforts to test the minicluster scenario using gravitational microlensing, and radio transients. Open problems surround both scenarios, related to the possible existence and survival fraction of the densest miniclusters.
Niklas Mueller, Univ. of Washington
[QCD theory Seminar] QCD meets Quantum Information Science -- Thermalization of Gauge Theories from their Entanglement Spectrum
The possibility to simulate quantum many-body systems with digital quantum computers and analog devices is an exciting opportunity for high energy and nuclear physics. One example is Entanglement Structure (ES), first explored in the context of non-Abelian fractional quantum Hall states, but largely unexplored for gauge theories and high energy and nuclear physics. ES is crucial e.g., to understand thermalization of the quark gluon plasma in ultra-relativistic heavy ion collisions, or the structure of QCD bound states in deeply inelastic scattering (DIS) at the future Electron-Ion Collider. To illustrate this, I will show how I used Entanglement Structure and Entanglement Tomography to gain insight into quantum thermalization of strongly-coupled gauge theories, which proceeds in characteristic stages and reveals quantum phenomena remarkably similar to their classical counterparts: chaos, turbulence and universality.
Miguel Montero, Harvard University
New String Theories from Discrete Theta Angles
Topological couplings play a prominent role in our understanding of field theories, but their role in string compactifications is much less understood. I explore an example in compactifications of type IIB string theory with sixteen supercharges, showing that they lead to previously unknown components of moduli space in nine, eight, and seven dimensions. I also explain why a similar construction fails to produce a new string theory in ten dimensions. The new components of moduli space thus constructed feature an incomplete lattice of BPS strings, which has implications for a number of Swampland constraints.
Aleksey Cherman, Univ. of Minnesota
[QCD theory Seminar] 1-form symmetry and large N QCD
The most modern way to understand quark confinement involves the notion of `1-form symmetry’. The reason we care about quark confinement is of course because of its implications for real-world QCD, but unfortunately confinement is believed to be only an approximate concept in the real world, so it is not tied to any exact symmetries. However, confinement is supposed to become well-defined in the large N limit of QCD, and so one might expect large N QCD to have a Z_N 1-form symmetry. However, to our surprise, in recent work we found some severe obstructions to the conjecture that large N QCD has a Z_N 1-form symmetry. Our results suggest that a symmetry-based understanding of (approximate) confinement in QCD may require some further generalization of the notion of generalized global symmetries.
Tomohiro Ishizu, Kansai University
[KEK IPNS-IMSS-QUP Joint Colloquium] Empirical approaches to study aesthetic experiences -an introduction to neuroaesthetics-