Masanori Hanada, University of Surrey
Large-N limit as a second quantization
Online (Zoom) https://kds.kek.jp/event/37783/ In gauge/gravity duality, the information regarding the gravitational geometry (e.g., black hole and smooth exterior geometry) has to be encoded in gauge theory. Clearly, the color degrees of freedom (matrix degrees of freedom) should play the key role, because the duality can hold even when the gauge theory side is a matrix model. In this talk, I will provide a simple way of encoding the geometry to matrices, along the line of Witten’s work on the effective action of D-branes and strings, and the Matrix Theory conjecture by Banks, Fischler, Shenker and Susskind. Roughly speaking, eigenvalues of matrices can be identified with the location of the D-brane probe or extended objects such as black hole.
In gauge/gravity duality, the information regarding the gravitational geometry (e.g., black hole and smooth exterior geometry) has to be encoded in gauge theory. Clearly, the color degrees of freedom (matrix degrees of freedom) should play the key role, because the duality can hold even when the gauge theory side is a matrix model. In this talk, I will provide a simple way of encoding the geometry to matrices, along the line of Witten’s work on the effective action of D-branes and strings, and the Matrix Theory conjecture by Banks, Fischler, Shenker and Susskind. Roughly speaking, eigenvalues of matrices can be identified with the location of the D-brane probe or extended objects such as black hole.
Actually there is a famous argument against such simple interpretation advocated by Polchinski in 1998. His argument used generic properties of large-N gauge theory to show that the ground-state wave function delocalizes at large N, leading to a conflict with the locality in the bulk geometry. We show that this argument is not correct: the ground-state wave function does not delocalize, and there is no conflict with the locality of the bulk geometry. In order to understand how the old argument fails, recently-discovered connection between color confinement and Bose-Einstein condensation is useful. This confinement-BEC connection has a striking consequence: in the SU(N) gauge theory, there is a partially-deconfined phase in which an SU(M)-subgroup is deconfined. Partial deconfinement, combined with the “eigenvalue = location” picture, provides us with a natural scenario to realize the idea in BFSS Matrix Theory conjecture — extended objects, such as black hole, are realized as bound states of D-branes and strings, that look like non-commutative blocks in big matrices — in the Maldacena-type gauge/gravity duality. In the large-N limit, various many-body states can be realized by considering block-diagonal matrix configurations, just as in the BFSS proposal. Therefore, the large-N limit of gauge theory can be interpreted as the second quantization of the gravity side.
If time permits, we will discuss how we might be able to check this proposal quantitatively, via classical or quantum simulations.
Christof Wetterich, Heidelberg University
Pregeometry and emergent general relativity
Online (Zoom) https://kds.kek.jp/event/37782/
Geometry is not fundamental. The metric and general relativity can emerge from more basic pregeometry. We formulate a euclidean functional integral for quantum gravity as a Yang-Mills theory with local gauge symmetry SO(4) and diffeomorphism invariance. It shows no instabilities and can be analytically continued to Minkowski signature. The quantum effective action leads to general relativity as an effective low energy theory. This ensures compatibility with the numerous precision tests for gravity. Adding a scalar field the cosmological solutions of the field equations describe an early inflationary epoch and late cosmology with dynamical dark energy and a candidate for dark matter. The beginning is a vacuum state which can be associated to the ultraviolet fixed point of the renormalisation flow. There is no big bang singularity.
Shu Lin, Sun Yat-Sen University
[QCD theory Seminar] Magneto-vortical effect in strong magnetic field
Online (Zoom)
We study the response of magnetized chiral plasma to transverse electric field and a steady vorticity. By solving chiral kinetic equation in the lowest Landau level approximation, we find the resulting current and stress tensor can be matched consistently with constitutive equations of magnetohydrostatics after we identify a vacuum shift in the case with vorticity. The solution in this case contains both shifts in temperature and chemical potential as well as excitations of the lowest Landau level states. It gives rise to an vector charge density and axial current density. The vacuum parts coming from both shifts and excitations agree with previous studies and the medium parts coming entirely from excitations leads to a new contribution to vector charge and axial current density, which is consistent with standard chiral vortical effect.
Masashi Aiko, Osaka University
Exploring the near alignment region in the two-Higgs doublet model
Online (Zoom), indico page, slides (kek.jp only)
In this talk, I discuss the phenomenology of the near alignment region in the two-Higgs doublet model (2HDM). It has turned out that the couplings of discovered Higgs boson with the SM particles are consistent with those in the SM within the experimental and theoretical uncertainties. One way to realize this SM-like limit in the 2HDM is the decoupling of the additional Higgs bosons. However, there is another way which is so-called alignment without decoupling motivated by some new physics scenario such as the electroweak baryogenesis. I show that the near alignment region where the Higgs couplings slightly deviate from the SM values can be widely explored by utilizing the synergy between the future hadron and lepton colliders. I would like to remark that this near alignment scenario is naturally predicted if the alignment is realized by the global symmetry of the Higgs potential at a higher energy scale. This talk is based on arXiv: 2009.04330 and 2010.15057.
Henry S. Lamm, Fermilab
Quantum Computation in Hadronic Physics
Online (Zoom)
The advent of quantum computation presents the opportunity to solve questions in hadronic physics which are inaccessible to classical computation such as real-time evolution and the equation of state at finite density. In order to take advantage of this new resource, a number of theoretical and computational hurdles will need to be addressed. In this talk, I will discuss the state of the art research being performed in hadronic physics and outstanding questions that require our attention going forward, focusing on digitization of gauge theories and extracting physical results that demonstrate practical quantum advantage.
Michio Kohno, RCNP, Osaka university
[EX] Baryon-baryon interactions in chiral effective field theory
Online (Zoom), indico page, slides (kek.jp only) Over the last two decades, the description of nucleon-nucleon (NN) interaction in chiral effective field theory has progressed. Based on the symmetry of QCD, together with the properties such as the precision equal to or better than other modern NN potentials for reproducing NN scattering data and the possibility of introducing more than three-body interactions in a systematic way, the ChEFT NN potentials now play a central role in the first-principle investigations of nuclear structure and reactions by using various methods of quantum many-body theory that have been developed around the same period. The ChEFT method is also applied to interactions in the strangeness sector. The seminar outlines the construction of the baryon-baryon interactions in chiral effective field theory.
Over the last two decades, the description of nucleon-nucleon (NN) interaction in chiral effective field theory has progressed. Based on the symmetry of QCD, together with the properties such as the precision equal to or better than other modern NN potentials for reproducing NN scattering data and the possibility of introducing more than three-body interactions in a systematic way, the ChEFT NN potentials now play a central role in the first-principle investigations of nuclear structure and reactions by using various methods of quantum many-body theory that have been developed around the same period. The ChEFT method is also applied to interactions in the strangeness sector. The seminar outlines the construction of the baryon-baryon interactions in chiral effective field theory.
・The idea of effective theory, and the general theory of effective interaction in a restricted space
・Chiral effective field theory (ChEFT)
・Parametrization of NN potentials in ChEFT
・Baryon-baryon potentials in the strangeness sector
・Comment: Present ChEFT NLO Xi-N interactions in view of the J-PARC E07 experiment
Sabyasachi Chakraborty, Florida State University
Heavy QCD axions in B decays
Online (Zoom)
We study B->Ka transition as a powerful probe of the heavy QCD axion (mass~GeV) by performing necessary 2-loop calculations for the first time. Such an axion is kinematically inaccessible or poorly constrained by most experimental probes. We will discuss some interesting subtleties of our calculation and present limits and projections on the axion parameter space using B-physics results.
Jay Armas, University of Amsterdam
Topological hydrodynamic modes on curved surfaces
Online (Zoom), indico page, slides (kek.jp only)
I will review the usage of topological methods in the case of the Dirac fermion and their role in predicting trapped edge modes. I will then show that these methods can be applied to classical systems, in particular to hydrodynamic systems that describe a broad range of phenomena, from geophysical waves to waves in topologically non-trivial soft matter experiments. Some of these system include activity (i.e. self-propelled organisms within the fluid). In particular, I will derive an index theorem that relates the topology of Fourier space determined by the underlying Hamiltonian with the real space topology of the surface in which the waves are hosted. At the end, I will give details about how the same methods can be applied to high energy physics, in particular to astrophysics and the AdS/CFT correspondence.
Noriyuki Sogabe, KEK / Institute of Moden Physics, CAS
Topological color-superconductivity in QCD with one flavor
Online (Zoom) https://kds.kek.jp/event/37256/ Superconductive gaps have topologically protected nodal structure if the fermions form the inter-chiral Cooper pair [1]. We generalize this Li and Haldane’s argument to the color superconductivity in QCD with one flavor. Among several order parameters with different spins and colors [ 2], we show that the nodes in the phases with a simple color-spin structure have the vortices characterized by the Berry monopoles, similarly to the previous literature. On the other hand, the paring function has no nodes if the color and spin degrees of freedom are entangled, such as in the ground state called the color-spin locking (CSL) phase. Even in this case, we find a non-trivial Berry curvature defined by the gap eigenvectors in the color-spin space. The CSL phase has an emergent Weyl fermion characterized by the doubled monopole charges as a quasi-particle. We discuss its possible relevance to the topological phase diagram of QCD with one flavor.
Superconductive gaps have topologically protected nodal structure if the fermions form the inter-chiral Cooper pair [1]. We generalize this Li and Haldane’s argument to the color superconductivity in QCD with one flavor. Among several order parameters with different spins and colors [ 2], we show that the nodes in the phases with a simple color-spin structure have the vortices characterized by the Berry monopoles, similarly to the previous literature. On the other hand, the paring function has no nodes if the color and spin degrees of freedom are entangled, such as in the ground state called the color-spin locking (CSL) phase. Even in this case, we find a non-trivial Berry curvature defined by the gap eigenvectors in the color-spin space. The CSL phase has an emergent Weyl fermion characterized by the doubled monopole charges as a quasi-particle. We discuss its possible relevance to the topological phase diagram of QCD with one flavor.
[1] Yi Li and F. D. M. Haldane, “Topological nodal Cooper pairing in doped Weyl metals,” Phys. Rev. Lett. 120, 067003 (2018).
[2] T. Sch?fer, “Quark hadron continuity in QCD with one flavor,” Phys. Rev. D 62, 094007 (2000).
Kazuki Ikeda, Osaka University / Kyocera
Real-time dynamics of Chern-Simons fluctuations near a critical point
Online (Zoom), indico page, slides (kek.jp only)
