DSpace Collection:https://scholars.lib.ntu.edu.tw/handle/123456789/284422023-12-02T22:57:17Z2023-12-02T22:57:17ZGravitational Faraday effect from on-shell amplitudesWei-Ming ChenMing-Zhi ChungYU-TIN HUANGJung-Wook Kimhttps://scholars.lib.ntu.edu.tw/handle/123456789/6340192023-07-21T07:32:59Z2022-05-15T00:00:00ZTitle: Gravitational Faraday effect from on-shell amplitudes
Authors: Wei-Ming Chen; Ming-Zhi Chung; YU-TIN HUANG; Jung-Wook Kim
Abstract: Effects of massive object's spin on massive-massless $2 \to 2$ classical
scattering is studied. Focus is set on the less-considered dimensionless
expansion parameter $\lambda/b$, where $\lambda$ is the massless particle's
wavelength and $b$ is the impact parameter. Corrections in $\lambda/b$ start to
appear from $\mathcal{O}(G^2)$, with leading correction terms tied to the
gravitational Faraday effect, which is a special case of the Lense-Thirring
effect. We compute the eikonal phase up to $\mathcal{O}(G^2)$ and extract spin
effect on the scattering angle and time delay up to 14th order in spin. The
gravitational Faraday effect at linear order in spin is reproduced by
$\lambda/b$ correction terms, which we compute to higher orders in spin. We
find that the equivalence principle, or universality, holds up to NLO for
general spinning bodies, i.e. away from geometric optics limit. Furthermore, in
the black hole limit, we confirm the absence of particular spin structure
observed, along with the associated shift symmetry, and argue that it holds to
arbitrary spin order at $\mathcal{O}(G^2)$ in the massless probe limit.
Description: published version; changed title; expanded discussions on the special
role of Kerr coupling in exponentiation; additional references; 45 pages, 4
figures, 1 ancillary file2022-05-15T00:00:00ZThe two-loop eight-point amplitude in ABJM theorySong HeYU-TIN HUANGChia-Kai KuoZhenjie Lihttps://scholars.lib.ntu.edu.tw/handle/123456789/6340182023-07-21T07:32:41Z2022-11-03T00:00:00ZTitle: The two-loop eight-point amplitude in ABJM theory
Authors: Song He; YU-TIN HUANG; Chia-Kai Kuo; Zhenjie Li
Abstract: In this paper, we present the two-loop correction to scattering amplitudes in
three-dimensional $\mathcal{N}=6$ Chern-Simons matter theory. We use
eight-point case as our main example, but the method generalizes to all
multiplicities. The integrand is completely fixed by dual conformal symmetry,
maximal cuts, constraints from soft-collinear behavior and from vanishing of
odd-multiplicity amplitudes. After performing integrations with Higgs
regularizations, the integrated results demonstrate that the infrared
divergence is again identical to that of ${\cal N}=4$ super Yang-Mills. After
subtracting divergences, the finite part is dual conformal invariant, and
respects various symmetries; it has uniform transcendentality weight two and
exhibits nice analytic structure.
Description: 57 pages, version accepted in JHEP2022-11-03T00:00:00ZPhase structure of the CP(1) model in the presence of a topological $θ$-termKatsumasa NakayamaLena FunckeKarl JansenYING-JER KAOStefan Kühnhttps://scholars.lib.ntu.edu.tw/handle/123456789/6340172023-07-21T07:25:51Z2021-07-30T00:00:00ZTitle: Phase structure of the CP(1) model in the presence of a topological $θ$-term
Authors: Katsumasa Nakayama; Lena Funcke; Karl Jansen; YING-JER KAO; Stefan Kühn
Abstract: We numerically study the phase structure of the CP(1) model in the presence
of a topological $\theta$-term, a regime afflicted by the sign problem for
conventional lattice Monte Carlo simulations. Using a bond-weighted tensor
renormalization group method, we compute the free energy for inverse couplings
ranging from $0\leq \beta \leq 1.1$ and find a CP-violating, first-order phase
transition at $\theta=\pi$. In contrast to previous findings, our numerical
results provide no evidence for a critical coupling $\beta_c<1.1$ above which a
second-order phase transition emerges at $\theta=\pi$ and/or the first-order
transition line bifurcates at $\theta\neq\pi$. If such a critical coupling
exists, as suggested by Haldane's conjecture, our study indicates that is
larger than $\beta_c>1.1$.
Description: 10 pages, 9 figures, v2: updated to match journal version2021-07-30T00:00:00ZVariational Tensor Network OperatorYu-Hsueh ChenKe HsuWei-Lin TuHyun-Yong LeeYING-JER KAOhttps://scholars.lib.ntu.edu.tw/handle/123456789/6340162023-07-21T07:25:33Z2022-07-05T00:00:00ZTitle: Variational Tensor Network Operator
Authors: Yu-Hsueh Chen; Ke Hsu; Wei-Lin Tu; Hyun-Yong Lee; YING-JER KAO
Abstract: We propose a simple and generic construction of the variational tensor
network operators to study the quantum spin systems by the synergy of ideas
from the imaginary-time evolution and variational optimization of trial wave
functions. By applying these operators to simple initial states, accurate
variational ground state wave functions with extremely few parameters can be
obtained. Furthermore, the framework can be applied to study spontaneously
symmetry breaking, symmetry protected topological, and intrinsic topologically
ordered phases, and we show that symmetries of the local tensors associated
with these phases can emerge directly after the optimization without any gauge
fixing. This provides a universal way to identify quantum phase transitions
without prior knowledge of the system.
Description: 16 pages, 12 figures2022-07-05T00:00:00Z