Masataka Watanabe, YITP
Callan-Rubakov effect and non-invertible defects
Online (Zoom)
There is a famous puzzle in QED coupled to N massless Dirac fermions that the scattering of a fermion off a monopole creates an out-state which cannot be any of the elementary particles in the theory. We give a new understanding of the s wave reduced version of the phenomena by interpreting the magnetic defect as a Tambara-Yamagami line defect.
Amarjit Soni, Brookhaven
Progress in eps' et al and the Kaon UT
Hybrid On-site: Kenkyu honkan, Seminar room Online: Zoom
For the past ~3 years we have been involved in an independent calculation of K=> 2 pi for the real and imaginary amplitudes and of direct CP violation parameter epsilon’ using periodic boundary conditions (PBC). In 2020 we reported the results using G-Parity BC (GPBC). The new calculation is giving us hope that we should be able to improve on the previous results. Furthermore, with new ideas we may be able to reduce the errors cn CKM parameter(s) using K^+ => pi^+ \nu +\bar nu. Thereby progress in the calculation of a Unitarty Triangle based primarily on K-decays will be discussed. This should provide a useful constraint on KL => pi^0 nu \bar nu which the KOPIO experiment at JPARC is trying to measure.
Michael J. Landry, MIT
[QCD theory Seminar] A systematic formulation of chiral anomalous magnetohydrodynamics
Online (Zoom)
We present a new way of deriving effective theories of dynamical electromagnetic fields in general media. It can be used to give a systematic formulation of magnetohydrodynamics (MHD) with strong magnetic fields, including systems with chiral matter and Adler-Bell-Jackiw (ABJ) anomaly. We work in the regime in which velocity and temperature fluctuations can be neglected. The resulting chiral anomalous MHD incorporates and generalizes the chiral magnetic effect, the chiral separation effect, the chiral electric separation effect, as well as recently derived strong-field MHD, all in a single coherent framework. At linearized level, the theory predicts that the chiral magnetic wave does not survive dynamical electromagnetic fields. A different chiral wave, to which we refer as the chiral magnetic electric separation wave, emerges as a result of dynamical versions of the chiral electric separation effect and the chiral magnetic effect. We predict its wave velocity. We also introduce a simple, but solvable nonlinear model to explore the fate of the chiral instability.
Axel Brandenburg, Nordita
[JpDe Joint Seminar] Origins of cosmic magnetism
Online (Zoom)
The magnetic fields of cosmic bodies like the Earth or the Sun have puzzled scientists for well over a hundred years. The basic principle is that of a self-excited dynamo, which is an electric generator where the weak permanent magnets are replaced by electromagnets. But cosmic dynamos are made of plasma with no wires and uniform conductivity, so they are prone to short-circuiting themselves. We now know of a handful of very different examples where a suitable flow geometry can exponentially amplify weak seed fields. Demonstrating this experimentally is still hard, but it did work in a few case. It is much easier on the computer. After explaining some of the examples, I will address the problem of primordial magnetic fields. For a long time, this was thought to be an alternative to galactic dynamos, but now we know that it is very much a research field in its own right. Not much is known with certainty, but there are believed to be lower observational limits on their strength. The field generation would also leave traces in relic gravitational waves, which is a rapidly growing topic that I will address at the end.
Kanji Mori, Fukuoka University
Core-collapse Supernovae as Laboratories for Axion-like Particles
Hybrid On-site: Seminar room, Kenkyu honkan 3F Online: Zoom Axion-like particles (ALPs) are a class of hypothetical pseudoscalar particles which feebly interact with ordinary matter. The hot plasma in core-collapse supernovae is a possible laboratory to explore physics beyond the standard model including ALPs. Once produced in a supernova, a part of the ALPs can be absorbed by the supernova matter and affect energy transfer. We recently calculated the ALP emission in core-collapse supernovae and the backreaction on supernova dynamics
Axion-like particles (ALPs) are a class of hypothetical pseudoscalar particles which feebly interact with ordinary matter. The hot plasma in core-collapse supernovae is a possible laboratory to explore physics beyond the standard model including ALPs. Once produced in a supernova, a part of the ALPs can be absorbed by the supernova matter and affect energy transfer. We recently calculated the ALP emission in core-collapse supernovae and the backreaction on supernova dynamics
consistently. It is found that the stalled bounce shock can be revived even in one-dimensional models if the coupling between ALPs and photons is as high as g_{a gamma} ~ 10^{-9} GeV^{-1} and the ALP mass is 40-400 MeV. In addition, we found that the explosion energy of supernovae can be increased by the ALP heating. This implies that ALPs can be a key to reproduce 10^51 erg explosion.
Valerie Domcke, CERN
Searching for high-frequency GWs with axion haloscopes
Hybrid On-site: Seminar room, Kenkyu honkan 3F Online: Zoomhttps://kds.kek.jp/event/45204/
Gravitational waves (GWs) generate oscillating electromagnetic effects in the vicinity of external electric and magnetic fields. I will discuss this phenomenon with a particular focus on reinterpreting the results of axion haloscopes based on lumped-element detectors, which probe GWs in the 100 kHz–100 MHz range. Measurements from ABRACADABRA and SHAFT already place bounds on GWs, although the present strain sensitivity is weak. However, the sensitivity scaling with the volume of such instruments is significant—faster than for axions—and so rapid progress will be made in the future. I will discuss opportunities at future facilities with a focus on the DMRadio program.
Glennys Farrar, New York University
[IPNS Physics Seminar] The muon g-2 and lattice QCD hadronic vacuum polarization may point to new, long-lived neutral hadrons
Hybrid On-site: Bldg.4 room 345, Online: Zoom
The experimental value the muon g-2 is 4.2 sigma larger than the Standard Model prediction, when the hadronic vacuum polarization contribution (HVP) is determined from the measured R-ratio. At the same time, the HVP calculated in lattice QCD also significantly exceeds the measured R-ratio value. A review of existing e+e experiments reveals that the contribution of certain types of hadronic final states would not have been counted, due to the event selection and trigger requirements of experiments to date. We further show that the lattice HVP and g-2 discrepancies can be naturally explained by an undetected contribution to e+e—> hadrons from production of previously unidentified neutral, long-lived hadrons. We suggest potential candidates for the new hadrons and propose several experimental tests. There are favorable cosmological and astrophysical impacts of Dark Matter having hadronic interactions, which will be discussed as time permits.
Daiki Suenaga, RIKEN
[QCD theory Seminar] Heavy-quark spin polarization induced by the Kondo effect in a magnetic field
Online (Zoom) The Kondo effect is one of the most important quantum many-body effects triggered by condensates made of a heavy impurity and a light fermion. Recently, importance of the Kondo effect in dense QCD has been discussed by regarding a heavy (charm or bottom) quark as the impurity in the light-quark medium, which is referred to as the QCD Kondo effect.
The Kondo effect is one of the most important quantum many-body effects triggered by condensates made of a heavy impurity and a light fermion. Recently, importance of the Kondo effect in dense QCD has been discussed by regarding a heavy (charm or bottom) quark as the impurity in the light-quark medium, which is referred to as the QCD Kondo effect.
Besides, properties of the Kondo effect were found to be described from a field theoretical approach, e.g., the NJL-type model together with the heavy-quark effective theory. In this talk I summarize the recent development of theoretical study of the QCD Kondo effect. Moreover, I explain the latest results of emergence of the heavy-quark spin polarization induced by the effect in a magnetic field, and show its relation to solid-state physics.
Chengpeng Yu, The University of Tokyo
Anomaly Induced Pulsar Kick
Hybrid On-site: Kenkyu honkan, Seminar room Online: Zoom
Pulsars, a special type of neutron star, often move at very high speed ($\sim 450 \mathrm{km/s}$), referred to as the pulsar kick phenomenon. However, why this high speed occurs is unclear. In this study, starting from realistic cooling model and equation of state, we analyzed the scattering between the neutrinos emitted during the cooling stage of a proto-neutron star and the anomalous axial current induced by the chiral separation effect in the star, and calculated the resulting time-dependent pulsar kick velocity.The result is: for isotropic axial current, the velocity is zero; however, with a 10\% anisotropic component of the axial current and the magnetic field strength $4\times 10^{11} \mathrm{T}$, the velocity is $223 \textrm{km/s}$. This value explains the well-known difference between the observed pulsar kick velocity ($\sim 450 \textrm{km/s}$) and the hydrodynamic simulation of supernova explosions ($\sim 200 \textrm{km/s}$). Hence, for the understanding of neutron star evolution during its early age, quantum anomaly is a crucial mechanism.
Samadrita Mukherjee, TIFR
A twisted tale of the transverse-mass tail in the W-boson mass measurement
Hybrid On-site: Kenkyu honkan, Seminar room Online: Zoomhttps://kds.kek.jp/event/44979/
