Miguel Montero, Harvard University
New String Theories from Discrete Theta Angles
Online (Zoom) https://kds.kek.jp/event/44336/
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
Online (Zoom)
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-
Online (Zoom)
Art and aesthetic experiences enrich our daily lives. It may appear distant from the empirical sciences at first glance, but it shares similar goals and is closely related to them in that it explores perception and engages with the workings of the mind. Neuroaesthetics is a discipline that studies the relationship between brain function and aesthetic experience (e.g., beauty, ugliness, being moved, sublime) as well as between cognitive processes and artistic activity (e.g. appreciation of artworks, artistic critique, creativity) using empirical methods from cognitive neuroscience. It is an interdisciplinary field that includes researchers from psychology, neuroscience, philosophy, art, art history, to welfare engineering. Following an overview of basic cognitive neuroscience research findings on aesthetic judgements such as beauty and ugliness, I will present research on more complex aesthetic experiences beyond simple beauty, such as sorrow and the sublime. Through these, I hope to explore what beauty means to humanity from a neuroaesthetics point of view.
Naritaka Oshita, RIKEN
Probing gravity with ringing black holes
Hybrid On-site: Kenkyu Honkan Seminar room 321, 322 Online: Zoomhttps://kds.kek.jp/event/44132/
A gravitational-wave (GW) signal emitted from a binary black hole merger is an important probe of gravity. The observation of GW ringdown allows us to perform a robust test of gravity as the ringdown waveform is a superposition of quasi-normal (QN) modes of the remnant black hole. It is known that black holes have an infinite number of QN modes. The precise measurement of multiple QN modes puts Einstein’s general relativity to the test. Also, the tentative detection of anomalous signals following the ringdown signal, i.e., GW echoes, has been claimed. The echo is postulated to be the footprint of quantum gravitational effects that can be significant in the vicinity of black hole horizons.I will explain how we can probe classical and quantum gravity with the observation of black hole ringing and will review the open issues and progress in this field.
Xu-Guang Huang, Fudan University
[QCD theory Seminar] QCD phase structure under rotation
Online (Zoom)
Due to the recent experimental breakthrough in heavy ion collisions about the spin polarization measurements, the QCD matter under rotation attracts a lot of attentions. Many novel phenomena are under intensive discussions, like the hyperon spin polarization, vector meson spin alignment, chiral vortical effects, and so on. It would be also interesting to ask what would be the effect of a global rotation on the QCD phase structure. The natural expectation would be that due to the spin polarization by rotation, all the spin-0 condensate, like the chiral condensate, would be unfavored and thus the chiral phase structure may vary under rotation. We will discuss whether this is the case for QCD by either model discussion and by lattice simulation. We will also discuss the confinement-deconfinement transtion under rotation.
Etsuko Itou, RIKEN
Velocity of Sound beyond the High-Density Relativistic Limit from Lattice Simulation of Dense Two-Color QCD
Online (Zoom) https://kds.kek.jp/event/43730/ We obtain the equation of state (EoS) for two-color QCD at low temperature and high density from the lattice Monte Carlo simulation. We find that the velocity of sound exceeds the relativistic limit (c_s^2/c^2=1/3) after BEC-BCS crossover in the superfluid phase. Such an excess of the sound velocity is predicted by several effective theories but is previously unknown from any lattice calculations for QCD-like theories.
We obtain the equation of state (EoS) for two-color QCD at low temperature and high density from the lattice Monte Carlo simulation. We find that the velocity of sound exceeds the relativistic limit (c_s^2/c^2=1/3) after BEC-BCS crossover in the superfluid phase. Such an excess of the sound velocity is predicted by several effective theories but is previously unknown from any lattice calculations for QCD-like theories.
This finding might have possible relevance to the EoS of neutron star matter revealed by recent measurements of neutron star masses and radii.
This talk is based on arXiv:2207.01253.
Guang Juan Wang, JAEA
The study of P-wave strange mesons in coupled channel framework
Hybrid On-site: Kenkyu Honkan Seminar room, Online (Zoom) https://kds.kek.jp/event/43887/
In this talk, I will discuss a novel framework to extract resonant states from finite-volume energy levels of lattice QCD and apply it to elucidate structures of the positive parity Ds resonant states nearby the DK and D*K thresholds. In the framework, the Hamiltonian effective field theory is extended by combining it with the quark model. The Hamiltonian contains the bare mesons from the quark model, its coupling with the threshold channels described by quark-pair-creation (QPC) model, and the channel-channel interactions induced by exchanging light mesons. A successful fit of the finite-volume energy levels of lattice QCD with the Hamiltonian model is made. The extracted masses and the predication for an additional state, Ds(2573), are well consistent with experimental measurements. The same framework has also be extended to the P-wave Bs states.
Sung Hak Lim, Rutgers University
Measuring Galactic Dark Matter through Unsupervised Machine Learning
Hybrid On-site: Kenkyu Honkan Seminar room, Online: (Zoom) https://kds.kek.jp/event/43893/
Measuring the density profile of dark matter in the Solar neighborhood has important implications for both dark matter theory and experiment. In this work, we apply autoregressive flows to stars from a realistic simulation of a Milky Way-type galaxy to learn — in an unsupervised way — the stellar phase space density and its derivatives. With these as inputs, and under the assumption of dynamic equilibrium, the gravitational acceleration field and mass density can be calculated directly from the Boltzmann Equation without the need to assume either cylindrical symmetry or specific functional forms for the galaxy’s mass density. We demonstrate our approach can accurately reconstruct the mass density and acceleration profiles of the simulated galaxy, even in the presence of Gaia-like errors in the kinematic measurements.
Kazushi Yamashiro, Shizuoka University
Target space entanglement in a matrix model for the bubbling geometry
Online (Zoom) https://kds.kek.jp/event/43729/
We study the target space entanglement entropy in a complex matrix model that describes the chiral primary sector in N=4super Yang-Mills theory, which is associated with the bubbling AdS geometry. The target space for the matrix model is a two-dimensional plane where the eigenvalues of the complex matrix distribute. The eigenvalues are regarded as the position coordinates of fermions, and the eigenvalue distribution can be viewed as a droplet formed by the fermions, which is identified with one that specifies a boundary condition in the bubbling geometry. We consider states in the matrix model that correspond to AdS5× S5, an AdS giant graviton and a giant graviton in the bubbling geometry. We calculate the target space entanglement entropy of a subregion for each of such states in the matrix model as well as the area of the boundary of the subregion in the bubbling geometry, and find a qualitative agreement between them.
Masaaki Tomii, Univ. of Connecticut
Lattice calculation of $K ¥to ¥pi¥pi$ decay on the lattice with periodic boundary conditions
Hybrid On-site: Kenkyu-Honkan Seminar room, Online: (Zoom) https://kds.kek.jp/event/43752/ Since RBC/UKQCD’s latest publication of lattice result for direct CP violation and the Delta I = 1/2 rule in $K ¥to ¥pi¥pi$ decay, which was made with G-parity boundary conditions in 2020, we have been revisiting this problem with a different lattice setup with periodic boundary conditions and multiple lattice spacings to see the consistency with our previous result and to improve the precision. While there was an expectation that it could be difficult to extract physical kinematics of K to pipi decay with periodic boundary conditions, we overcome it through the variational method. Also periodic boundary conditions provide a relatively easy way to introduce electromagnetic and isospin breaking corrections, which is desired to be implemented in near future.
