Toru Kojo, Tohoku University
Sound velocity peak as a signature of quark matter formation
Online (Zoom)
Sound velocity characterizes how the stiffness of matter changes as density increases. Nuclear many-body calculations and nuclear constraints indicate that matter is soft up to 1-2n0 (nuclear saturation density), while neutron star observations require stiff matter around 3-5n0 to pass the so-called two-solar mass constraint. This suggests that the QCD equation of state must have soft-to-stiff evolution in the interval of 2-5n0. Purely nuclear matter calculations typically lead to gentle stiffening to ~5n0.. We argue that the quark substructure of baryons is important even before baryons substantially overlap, leading to rapid stiffening and the sound velocity peak. These features are implemented in the Quark-Hadron-Crossover (QHC) equation of state (EOS). Using this EOS we study neutron star observables, in particular, gravitational waves in the post-merger phase, and quantify how large the impact of the sound velocity peak can be.
John Ellis, King's College
Atom Interferometer experiments to search for ultralight dark matter and gravitational waves
Hybrid On-site: Seminar room, Kenkyu honkan 3F Online:(Zoom)
Atom interferometers measure the quantum interference between cold atoms in clouds following different space-time trajectories, which is sensitive to phase shifts induced by interactions with ultralight dark matter or the passage of gravitational waves. The capabilities of atom interferometers will be illustrated by their estimated sensitivities to the possible couplings of ultralight dark matter to electrons and photons, and to gravitational waves in the frequency range around 1 Hz intermediate between the peak sensitivities of the LIGO and LISA experiments. The latter open a window on mergers of masses intermediate between those discovered by the LIGO and Virgo experiments and the supermassive black holes present in the cores of galaxies, as well as fundamental physics processes in the early Universe.
Roman Zwicky, the University of Edinburgh
Massive Hadrons and Conformality
Hybrid On-site: Seminar room, Kenkyu honkan 3F 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: 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
