Tomomi Sunayama, IPMU
Cosmology with Subaru Prime Focus Spectrograph (PFS)
Meeting room 1, Kenkyu honkan 1F
PFS (Prime Focus Spectrograph), a next generation facility instruments on the Subaru telescope, is a wide-field, massively multiplexed, and optical & near-infrared spectrograph. In the PFS cosmology survey, emission line galaxies (ELGs) in the wide redshift range from z= 0.6to2.4 over 1400 square-degree will be observed. The unique redshift range for the PFS cosmology survey is at z>2. We envision that we will start our survey from 2022, and I will describe strategies to achieve the scientific goals as well as the possible systematic problems for future fiber-fed spectroscopic surveys.
Po-Yen Tseng, Yonsei University
Light gauge boson interpretation for muon g-2 and J-PARC KOTO anomalies
Meeting room 3, Kenkyu honkan 1F
We discuss a list of possible light gauge boson interpretations for the long-standing experimental anomaly in $(g-2)\mu$ and also recent anomalous excess in $KL \rightarrow \pi^0 + \text{(invisible)}$ events at the J-PARC KOTO experiment. We consider two models: i) $L\mu – L\tau$ gauge boson with heavy vector-like quarks and ii) $(L\mu – L\tau) + \epsilon (B3 – L\tau)$ gauge boson in the presence of right-handed neutrinos. When the light gauge boson has mass close to the neutral pion in order to satisfy the Grossman-Nir bound, the models successfully explain the anomalies simultaneously while satisfying all known experimental constraints. We extensively provide the future prospect of suggested models.
Tatsuhiro Misumi, Akita University
Central-branch Wilson fermion, Spin chain and Aoki phase
Meeting room 1, Kenkyu honkan 1F In this talk, we first discuss the central-branch Wilson fermion, which is defined by imposing a specific relation between the mass and the Wilson parameter [1]. This setup gives two massless Dirac fermions in the continuum limit, and it turns out that no fine-tuning of m is required because the extra U(1) symmetry at the central branch prohibits the additive mass renormalization [2,3]. We show that Dirac determinant is positive semi-definite and this formulation is free from the sign problem, so the Monte Carlo simulation of the path integral is possible. By identifying the symmetry at low energy, we find that this lattice model has the mixed ’t Hooft anomaly between the extra U(1) symmetry, lattice translation, and lattice rotation, which means that the trivially gapped phase is forbidden at the central branch [4]. We discuss its relation to the anomaly of half-integer anti-ferromagnetic spin chains, so our lattice gauge theory is suitable for numerical simulation of Haldane conjecture. We also argue that it gives new and strict understanding on parity-broken phase (Aoki phase) of 2d Wilson fermion [4]. Furthermore, we show that our study can be extended to 4d lattice QCD with Wilson fermion, leading to a novel insight into the question which of Aoki-phase or Sharpe-Singleton scenarios is valid.
In this talk, we first discuss the central-branch Wilson fermion, which is defined by imposing a specific relation between the mass and the Wilson parameter [1]. This setup gives two massless Dirac fermions in the continuum limit, and it turns out that no fine-tuning of m is required because the extra U(1) symmetry at the central branch prohibits the additive mass renormalization [2,3]. We show that Dirac determinant is positive semi-definite and this formulation is free from the sign problem, so the Monte Carlo simulation of the path integral is possible. By identifying the symmetry at low energy, we find that this lattice model has the mixed ’t Hooft anomaly between the extra U(1) symmetry, lattice translation, and lattice rotation, which means that the trivially gapped phase is forbidden at the central branch [4]. We discuss its relation to the anomaly of half-integer anti-ferromagnetic spin chains, so our lattice gauge theory is suitable for numerical simulation of Haldane conjecture. We also argue that it gives new and strict understanding on parity-broken phase (Aoki phase) of 2d Wilson fermion [4]. Furthermore, we show that our study can be extended to 4d lattice QCD with Wilson fermion, leading to a novel insight into the question which of Aoki-phase or Sharpe-Singleton scenarios is valid.
[References]
[1] M. Creutz, T. Kimura, T. Misumi, Phys. Rev. D83 (2011) 094506, [arXiv:1101.4239].
[2] T. Kimura, S. Komatsu, T. Misumi, T. Noumi, S. Torii, S. Aoki, JHEP 01 (2012) 048, [arXiv:1111.0402].
[3] T. Misumi, PoS LATTICE2012 (2012) 005, [arXiv:1211.6999].
[4] T. Misumi, Y. Tanizaki, [arXiv:1910:09604].
Sanefumi Moriyama, Osaka City University
ABJM Matrix Model and 2D Toda Lattice Hierarchy
Meeting room 1, Kenkyu honkan 1F
It was known that the worldvolume of multiple M2-branes is described by 3D supersymmetric Chern-Simons theory (known as ABJM theory). After moving to the grand canonical ensemble, it was found in our previous works that the vacuum expectation values of half-BPS Wilson loops in the ABJM theory satisfy Giambelli relations and Jacobi-Trudi relations, which imply integrability directly. To investigate the integrable structure, we further defined two-point functions in ABJM matrix model and identified the structure as 2D Toda lattice hierarchy. In this talk I will give an overview of the recent progress on integrability in the ABJM theory.
Noriyuki Sogabe, Keio U
Triangle anomalies and nonrelativistic Nambu-Goldstone modes of generalized global symmetries
Meeting room 1, Kenkyu honkan 1F In massless QCD coupled to QED in an external magnetic field, a photon with the linear polarization in the direction of the external magnetic field mixes with the charge neutral pion through the triangle anomaly, leading to one gapless mode with the quadratic dispersion relation ω?k^2 and one gapped mode. In this talk, we show that this gapless mode can be interpreted as the so-called type-B Nambu-Goldstone (NG) mode associated with the spontaneous breaking of the generalized global symmetries and that its presence is solely dictated by the anomalous commutator in the symmetry algebra. We also argue a possible realization of such nonrelativistic NG modes in 3-dimensional Dirac semimetals.
In massless QCD coupled to QED in an external magnetic field, a photon with the linear polarization in the direction of the external magnetic field mixes with the charge neutral pion through the triangle anomaly, leading to one gapless mode with the quadratic dispersion relation ω?k^2 and one gapped mode. In this talk, we show that this gapless mode can be interpreted as the so-called type-B Nambu-Goldstone (NG) mode associated with the spontaneous breaking of the generalized global symmetries and that its presence is solely dictated by the anomalous commutator in the symmetry algebra. We also argue a possible realization of such nonrelativistic NG modes in 3-dimensional Dirac semimetals.
Syuhei Iguro, Nagoya University
Testing the 2HDM explanation of the muon g-2 anomaly at the LHC
Meeting room 3, Kenkyu honkan 1F
The discrepancy between the measured value and the Standard Model prediction for the muon anomalous magnetic moment is one of the important issues in the particle physics. In this talk, we consider a two Higgs doublet model (2HDM) where the extra Higgs doublet couples to muon and tau in lepton flavor violating (LFV) way and the one-loop correction involving the scalars largely contributes to the muon anomalous magnetic moment. The couplings should be sizable to explain the discrepancy, so that the extra Higgs bosons would dominantly decay into μτ LFV modes, which makes the model testable at the LHC through multi-lepton signatures even though they are produced via the electroweak interaction. We discuss the current status and the future prospect for the extra Higgs searches at the LHC, and demonstrate the reconstruction of the mass spectrum using the multi-lepton events.
Shintaro Eijima, KEK
Sterile neutrino dark matter and heavy neutral leptons
Meeting room 1, Kenkyu honkan 1F
Sterile neutrino as a possible dark matter candidate is reviewed. I will give an overview of the current status of the research on the dark matter particle, and discuss the motivation and limits obtained through astrophysical observations. Originally the thermal production via mixing was suggested which, however, is ruled out in current constraints. I will introduce different mechanisms to produce the dark matter. In particular a resonant production with lepton asymmetry in thermal plasma and the asymmetry originated by heavy neutral leptons are explained.
Etsuko Itou, Keio University
Two-colour QCD phases and the topology at low temperature and high density
Meeting room 1, Kenkyu honkan 1F
>We delineate equilibrium phase structure and topological charge distribution of dense two-colour QCD at low temperature by using a lattice simulation with two-flavour Wilson fermions that has a chemical potential μ and a diquark source j incorporated. We systematically measure the diquark condensate, the Polyakov loop, the quark number density and the chiral condensate with improved accuracy and j→0 extrapolation over earlier publications; the known qualitative features of the low temperature phase diagram, which is composed of the hadronic, Bose-Einstein condensed (BEC) and BCS phases, are reproduced. In addition, we newly find that around the boundary between the hadronic and BEC phases, nonzero quark number density occurs even in the hadronic phase in contrast to the prediction of the chiral perturbation theory (ChPT), while the diquark condensate approaches zero in a manner that is consistent with the ChPT prediction. At the highest μ, which is of order the inverse of the lattice spacing, all the above observables change drastically, which implies a lattice artifact. Finally, at temperature of order 0.45Tc, where Tc is the chiral transition temperature at zero chemical potential, the topological susceptibility is calculated from a gradient-flow method and found to be almost constant for all the values of μ ranging from the hadronic to BCS phase. This is a contrast to the case of 0.89Tc in which the topological susceptibility becomes small as the hadronic phase changes into the quark-gluon plasma phase. This talk is based on arXiv:1910.07872.
Daisuke Nomura, KEK
[IPNS Physics Seminar] The muon g-2: a new data-analysis
Room 345, bldg. 4
Following updates in the compilation of e^+ e^- –> hadrons data, I will talk about re-evaluations of the hadronic vacuum polarization contributions to the anomalous magnetic moment of the muon (a_¥mu). Combining the results for the hadronic vacuum polarization contributions with recent updates for the hadronic light-by-light corrections, the electromagnetic and the weak contributions, the deviation between the measured value of a_¥mu and its Standard Model prediction amounts to ¥Delta a_¥mu = (28.02 +/- 7.37) x 10^{-10}, corresponding to a muon g-2 discrepancy of 3.8 ¥sigma.
Gerald V. Dunne, University of Connecticut
[12th KEK joint colloquium] Decoding the Path Integral: Resurgence and Non-Perturbative Physics
Kobayashi hall, Kenkyu honkan 1F There are several important conceptual and computational questions concerning the Minkowski space path integral, which have recently been approached from a new perspective motivated by “resurgent asymptotics”, which is a novel mathematical formalism that seeks to unify perturbative and non-perturbative physics. In this general talk, I will introduce the basic ideas, report on some examples in quantum mechanics and quantum field theory, and discuss future prospects.
