Yevgeny Stadnik, Kavli IPMU, University of Tokyo
Novel low-energy probes of dark matter
Seminar room, Kenkyu honkan 3F
I present a brief overview of some novel detection strategies for ultra-low-mass bosonic dark matter that forms a coherently oscillating classical field. Possible effects of such dark-matter fields include apparent time-varying fundamental constants and time-varying spin-precession effects. These effects can be sought with a diverse variety of high-precision, low-energy (and often table-top) experiments, including: spectroscopy (clock) and optical cavity measurements, laser interferometers, atom interferometers, torsion pendula (fifth-force experiments), magnetic resonance techniques, and astrophysical measurements (such as big bang nucleosynthesis). Existing and new experimental and observational data have allowed us and other groups to improve on previous observational bounds on possible non-gravitational interactions of ultra-low-mass dark matter with ordinary matter by many orders of magnitude.
Kenji Kadota, Center for Theoretical Physics of the Universe (CTPU), Institute for Basic Science (IBS)
Radio telescope probes on the light dark matter
Meeting room 1, Kenkyu honkan 1F
An overview for the light dark matter will be presented along with the illustration for the complementarity between the cosmology and particle physics probes. The concrete examples include the radio emission from the axion-photon conversion around the neutron star and the cross-correlations between the 21cm and the CMB B mode from the cosmological birefringence.
Christian Rohrhofer, Osaka University
Two Flavor QCD Spectrum and Symmetries at High Temperature
Meeting room 1, Kenkyu honkan 1F QCD matter and properties change significantly around the chiral crossover temperature, and so far the effects on chiral observables and thermodynamical quantities have been studied with much care.
QCD matter and properties change significantly around the chiral crossover temperature, and so far the effects on chiral observables and thermodynamical quantities have been studied with much care.
Here I present the screening spectrum for light hadrons, which includes chiral partners of mesons as well as different nucleon operators and their parity partners.
Measurements are done with two flavors of chirally symmetric domain-wall fermions at temperatures above the critical one, for different volumes and quark-masses.
Emergent SU(4) and SU(2)_CS symmetries will be discussed, as well as their implications.
Luigi Accardi, University of Rome Tor Vergata
Extensions of Quantum Mechanics Canonically Emerging from the Theory of Orthogonal Polynomials
Seminar room, Kenkyu honkan 3F
For more than one century quantum mechanics has been considered a singular theory, uniquely related to quantum physics. In the past few years it has become clear that all the basic structures of quantum theory naturally emerge from a combination of classical probability with the theory of orthogonal polynomials. In fact any classical random variable has a canonical quantum decomposition as a sum of 3 linear operators called respectively: generalized creation, annihilation and preservation (CAP) operators. These operators satisfy generalized commutation relations (GCR) that are natural extensions of Heisenberg commutation relations and characterize the given random variable in the sense of moments. The Heisenberg commutation relations characterize the Gaussian class which is included in the larger class of measures ”linearly equivalent” to product measures. This larger class is characterized by the property that CAP operators associated to different degrees of freedom commute. Thus usual quantum mechanics belongs to this class. For this class the theory of multi—dimensional orthogonal polynomials is essentially reduced to the tensor product of 1-dimensional cases. For truly interacting random variables (or fields) new commutations relations arise from the commutativity of the multiplication operators associated to different components of the random variable. In this sense non-commutativity arises from commutativity. The construction has functorial properties that generalize the usual Fock functor.
Yoichi Kazama, Rikkyo University
Issues in Quantum Gravity
Seminar room, Kenkyu honkan 3F, slides (kek.jp only) Among the important questions that remain after the success of the standard model, by far the most fundamental would be the understanding of quantum gravity, which is not only of utmost academic interest but also might play the key role in the observational cosmology in an unexpectedly near future.
Among the important questions that remain after the success of the standard model, by far the most fundamental would be the understanding of quantum gravity, which is not only of utmost academic interest but also might play the key role in the observational cosmology in an unexpectedly near future.
Although many studies are made on this subject, more often than not, papers on “quantum gravity” actually discuss quantum behavior of matter fields in a (semi-)classical gravity background. Clearly, what is required, however, is a bona fide understanding of the quantization of gravity itself.
In this talk, I wish to make an attempt to
(i) clarify what the essential issues of quantum gravity are,
(ii) survey the present status of our understanding, and
(iii) look for promissing directions of attack,
Yuichiro Tada, Nagoya University
Aspects of primordial black hole in the light of gravitational wave
Room 345, 4 go-kan
Since Carr and Hawking proposed it more than 4 decades ago, primordial black hole (PBH) has attracted people and is increasing its importance more recently. It can explain ubiquitous massive BHs for LIGO/Virgo events, the main component of dark matters, etc., etc. The key point is that, once abundant PBHs are required, it might change the “naturalness” of inflation: the small scale perturbations are free from the CMB scale and might have a large amplitudes. In such a case, stochastic gravitational waves (GWs) induced by the large density perturbations get important. They are not just an evidence of large perturbations but also can carry the information of phase transitions in the universe such as QCD and/or EW. In this talk, I will introduce the astrophysical motivations of PBH, its implication to theories of inflation, and future possibilities in the light of stochastic GWs.
Rodrigo Alonso De Pablo, Kavli IPMU, University of Tokyo
On resonances, amplitudes and the UV completion of gravity
Meeting room 1, Kenkyu honkan 1F
We will construct, making use of the on-shell amplitude methods, a possible ultraviolet completion of gravity following a “bottom-up” approach. The assumptions of locality, unitarity and causality i) require an infinite tower of resonances with increasing spin and quantized mass, ii) introduce a duality relation among crossed scattering channels, and iii) dress all gravitational amplitudes in the Standard Model with a form factor that closely resembles either the Veneziano or the Virasoro-Shapiro amplitude in string theory. As a consequence of unitarity, the theory predicts leading order deviations from General Relativity in the coupling of gravity to fermions that can be explained if space-time has torsion in addition to curvature.
Jonathan Miller, OIST
[10th KEK joint colloquium] Psychophysics of Cephalopod Camouflage: What is the input/output response function of a Cuttlefish？カモフラージュの精神物理学：コウイカは何を「考えて」身体模様を変化させるのか？
Seminar hall 4 go-kan / Room 324 1 go-kan Tokai campus（TV link） The physicist and philosopher Hermann von Helmholtz, whose foundational contributions to physics you all know very well, also invented “psychophysics,” a paradigm for phenomenology by
The physicist and philosopher Hermann von Helmholtz, whose foundational contributions to physics you all know very well, also invented “psychophysics,” a paradigm for phenomenology by
– inferring minimal predictive quantitative models;
– combining physical calculations and behavioral studies to establish that human color vision is trichromatic.
Detailed mechanisms were confirmed a century later by electro/neurophysiological, genetic/genomic and biochemical methods. Now phenomenology can drive development of novel AI/machine learning technology by elucidating the neuroscience, principles and computational algorithms of cognitive processing in humans and animals. Think of, for example, generalized adversarial networks [GAN], the state of the art in deconstructing human visual processing.
Cephalopods (octopus, cuttlefish, and squid) modulate their skin color and texture to match their marine backgrounds on millisecond timescales; in this sense, they “report” to us their perceptions. I will describe how biologists in my unit at OIST have developed a flexible model organism ideal for deconstructing this process. Living organisms are wetware, and as such one role of science is to establish their device characteristics. My unit is pursuing the development of customized physical hardware, algorithms, and software to quantitatively probe the i/o response function of this model organism, and to reverse engineer the biophysics and neural algorithms of its cognition and consciousness.
Yoshinobu Kuramashi, University of Tsukuba
Application of Tensor Renormalization Group to Particle Physics
Meeting room 1, Kenkyu honkan 1F
Tensor renormalization group, which is a numerical algorithm in tensor network scheme, has fascinating features: (i) no sign problem, (ii) logarithmic volume dependence of computational cost, (iii) direct treatment of Grassmann variables, (iv) direct measurement of partition function itself. These inspires the interest across various research fields. Application of tensor renormalization group to particle physics has been led by our group. I will explain the recent progress of our research.
Ping Yeh, Google
[IPNS Physics/Theory Seminar] Google's quantum computer and pursuit of quantum supremacy
Room 345, 4 go-kan
