Roman Zwicky, Edinburgh

Massive Hadrons and Conformality

Hybrid On-site: Seminar room 321, 322. Online:(Zoom)
I will advocate a phase of gauge theories where the long distance scale symmetry is spontaneously broken by the quark condensate. This phase allows for massive hadrons and requires a dilaton, a genuine goldstone boson, which restores the Ward identities. I will discuss this on the example of the gravitational form factors. I will discuss the response of this system to explicit scale breaking of quark masses. At the end I will speculate that QCD itself and the Higgs sector could be of this type.

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: Seminar room 322, 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.

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 Onsite: Kenkyu-Honkan Seminar room, 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
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 322, Online (Zoom) https://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.

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.
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:Seminar room 322, 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: Seminar room 321, 322. Online:(Zoom) https://kds.kek.jp/event/44979/
The discrepant measurement of the W mass by the CDF collaboration can be made consistent with all other current measurements, by the ATLAS, the LHCb, the D0, the LEP collaborations, and with the electroweak precision fit for $M_W$ in a minimal—albeit naive— an extension of the Standard Model. In our setup, there is only one new operator and a single new (pseudo-)scalar particle which manifests as an unaccounted-for contribution to missing energy. This simple extension is enough to simultaneously explain the different extractions of $M_W$ for a sizeable chunk of the parameter space. We support our analysis by extracting novel bounds on the new physics scenario from W-cross-section measurements and $WW$ cross-section measurements to show that parts of the parameter space are, indeed, still allowed. We also discuss possible ultraviolet completions of the setup. Finally, we present our predictions for $M_W$ that ATLAS and CMS would extract from their 13 TeV data.

[Cosmophysics Seminar] Impact of half-wave plate systematics on the measurement of cosmic birefringence from CMB polarization

Online (Zoom)
Polarization of the cosmic microwave background (CMB) can probe new parity-violating physics such as cosmic birefringence (CB), which requires exquisite control over instrumental systematics. The non-idealities of the half-wave plate (HWP) represent a source of systematics when used as a polarization modulator. We study their impact on the CMB angular power spectra, which is partially degenerate with CB and miscalibration of the polarization angle. We use full-sky beam convolution simulations including HWP to generate mock noiseless time-ordered data, process them through a bin averaging map-maker, and calculate the power spectra including TB and EB correlations. We also derive analytical formulae which accurately model the observed spectra. For our choice of HWP parameters, the HWP-induced angle amounts to a few degrees, which could be misinterpreted as CB. Accurate knowledge of the HWP is required to mitigate this. Our simulation and analytical formulae will be useful for deriving requirements for the accuracy of HWP calibration.

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