Masanori Hanada, Queen Mary University of London

[QCD theory seminar] Color Confinement and Random Matrices

Oneine (Zoom)
We describe how the general mechanism of partial deconfinement applies to large-N QCD and the partially deconfined phase inevitably appears between completely-confined and completely-deconfined phases. Furthermore, we propose how the partial deconfinement can be observed in the real-world QCD with the SU(3) gauge group. For this purpose, we employ lattice configurations obtained by the WHOT-QCD collaboration and examine our proposal numerically. In the discussion, the Polyakov loop plays a crucial role in characterizing the phases, without relying on center symmetry, and hence, we clarify the meaning of the Polyakov loop in QCD at large N and finite N. As a nontrivial test for our proposal, we also investigate the relation between partial deconfinement and instanton condensation and confirm the consistency with the lattice data. As a nontrivial application, we show that computation of the two-point correlator of Polyakov loops in the confined phase reduces to the problem of random walk on group manifold. As a consequence, linear confinement potential with approximate Casimir scaling follows immediately.

Ten Brandes, Munich Tech U

Constraints on Phase Transitions in Neutron Star Matter

Online (Zoom)
Recent inference results of the sound velocity in the cores of neutron stars are summarized. Implications for the equation of state and the phase structure of highly compressed baryonic matter are discussed. In view of the strong constraints imposed by the heaviest known pulsars, the equation of state must be very stiff in order to ensure the stability of these extreme objects. This required stiffness limits the possible appearance of phase transitions in neutron star cores. For example, a Bayes factor analysis quantifies strong evidence for squared sound velocities c_s^2 > 0.1 in the cores of 2.1 solar-mass and lighter neutron stars. Only weak first-order phase transitions with a small phase coexistence density range \Delta\rho/\rho < 0.2 (at the 68\% level) in a Maxwell construction still turn out to be possible within neutron stars. The central baryon densities in even the heaviest neutron stars do not exceed five times the density of normal nuclear matter. In view of these data-based constraints, much discussed issues such as the quest for a phase transition towards restored chiral symmetry and the active degrees of freedom in cold and dense baryonic matter, are reexamined.

Aleskey Cherman, MInnesota U

Exact lattice chiral symmetry in 2d gauge theory

Online (Zoom)
Preserving the symmetries of massless fermions is a well-known challenge in lattice field theory. I’ll discuss symmetry-preserving lattice regularizations of 2d QED with one and two flavors of Dirac fermions, as well as the `3450′ chiral gauge theory. The construction leverages bosonization and recently-proposed modifications of Villain-type lattice actions. The internal global symmetries act just as locally on the lattice as they do in the continuum, the anomalies are reproduced at finite lattice spacing, and in each case we’ve found a sign-problem-free dual formulation.

鈴木勝彦, 海底資源センター

[金茶会] 第6回 海洋鉱物資源:放射光や同位体を用いた有用金属濃集プロセスの研究から環境影響評価まで

東海:J-PARC研究棟2階会議室 (リモート会場:つくば3号館セミナーホール)


Xiaojun Yao, Univ. of Washington

[QCD theory seminar] When is axial gauge applicable?

Oneine (Zoom)
Axial gauge has been used in many perturbative calculations. However, it sometimes leads to puzzling results. In this talk, I will discuss a specific example in the context of heavy quark and quarkonium transport coefficients, where naive application of temporal axial gauge leads to an incorrect result. Then I will discuss the origin of the problem from both perturbative and nonperturbative aspects. Finally I will summarize the applicability condition of axial gauge and give a few examples.

Ippei Obata, KIPMU

Parity-violating scalar trispectrum from axion inflation

Hybrid On-site: Kenkyu Honkan Seminar room 321, 322 Online: Zoom
We study a mechanism of generating the trispectrum (4-point correlation) of curvature perturbation through the dynamics of a spectator axion field and U(1) gauge field during inflation. Owing to the Chern-Simons coupling, only one helicity mode of the gauge field experiences a tachyonic instability and sources scalar perturbations. Sourced curvature perturbation exhibits parity-violating nature which can be tested through its trispectrum. We numerically compute the parity-even and parity-odd components of the sourced trispectrum. It is found that the ratio of parity-odd to parity-even mode can reach O(10%) in an exact equilateral momentum configuration. We also investigate a quasi-equilateral shape where only one of the momenta is slightly longer than the other three, and find that the parity-odd mode can reach, and more interestingly, surpass the parity-even one. This may help us to interpret a large parity-odd trispectrum signal extracted from BOSS galaxy-clustering data.

Teppei Kitahara, CAS

[IPNS Physics and Theory Seminar] Recent Progress and Future Prospects in Flavor Physics

Hybrid On-site: Kobayashi Hall Online: Zoom
Flavor physics is the field that explores new physics in a bottom-up approach by comprehensive and precise measurements of processes that occur through weak interactions, leading to small theoretical uncertainty. Flavor physics is also the only method that can observe CP violation at this moment. The goal is to explore the mysteries of matter-antimatter asymmetry and the origin of flavor structures. In recent years, progress in experimental techniques and improvements in lattice QCD simulations have boosted sensitivity to new physics, and even reported several flavor anomalies. Based on this background, I will present some of the recent flavor theories and their future prospects, and also discuss physics related to B anomaly, which is currently attracting particular attention.

Minoru Tanaka, Osaka University

Isotope shift as a probe of new physics

Hybrid On-site: Kenkyu Honkan Seminar room 321, 322 Online: Zoom

Isotope shift (IS) in atomic spectra is sensitive to a new interaction between the electron and the neutron. In the standard model (SM) of particle physics, the finite nuclear mass and size varying from one isotope to another cause the IS. Since the theoretical calculation of IS is not easy, even in the SM, we introduce a new method to search for the new interaction. Our method employs a generalization of the King linearity of IS, the generalized IS linearity.
We apply various generalized linearities to recent IS data of Ytterbium (Yb) and illustrate constraints on the new interaction.

K. Mikami, MT, Y.Yamamoto, EPJC 77, 896 (2017)
K. Ono, MT et al. PRX 12, 021033 (2022)

高柳匡, 京都大学基礎物理学研究所

[金茶会] 第5回 時空は幻想?量子力学とブラックホールの不思議な物語

つくば:4号館セミナーホール (リモート会場:J-PARC研究棟2階会議室)


Laszlo Feher, Szeged University

Bi-Hamiltonian structures of integrable many-body models

Seminar room, Kenkyu Honkan 3F
The evolution equations of several exactly solvable dynamical systems can be written in Hamiltonian form in two distinct manners, using two different Poisson bracket structures and corresponding Hamiltonians. Such bi Hamiltonian structures lead to the existence of conserved quantities associated with the integrability of the pertinent systems. In this talk we review our results on bi-Hamiltonian structures of integrable many-body models of point particles moving along one dimension, which are also coupled to internal `spin’ degrees of freedom. The models of our interest belong to the celebrated family of Calogero–Moser–Sutherland and Toda type systems. They will be viewed as shadows (alias Poisson reductions) of simple higher dimensional bi-Hamiltonian systems having large symmetry groups.

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