セミナー 2022年

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.

Kyohei Mukaida, KEK

[QCD theory Seminar] Chiral asymmetry in the early Universe

Online (Zoom)
Since the SM model is a chiral theory, asymmetries in matter generically result in chiral asymmetries. Nevertheless, the effect of the primordial chiral asymmetry is often neglected in the study of the early Universe because the baryon asymmetry is tiny. In this talk, I will discuss some examples where the chiral asymmetry plays essential roles, in particular in the context of baryogenesis.

小野 寛太, 大阪大学

[KEK連携コロキウム] 量子ビーム計測の自律化

ハイブリッド形式 : オンライン (Zoom) + セミナールーム(研究本館321)

Hidenori Fukaya, Osaka University

Curved domain-wall fermion and its anomaly inflow

Online (Zoom) https://kds.kek.jp/event/44588/
We consider a fermion system on a square lattice, where a curved domain-wall is assigned to the mass term. In a similar way to the standard flat domain-wall fermion, chiral edge modes appear at the wall. These edge-localized modes feel gravity, through the induced spin connection or metric due to the Einstein’s equivalence principle.
In the cases of circle $S^1$ and sphere $S^2$ domain-walls embedded into higher dimensional square lattices of one dimension higher, we numerically confirm the existence of the edge-localized modes and the effect of gravity encoded in the spectrum. With $U(1)$ link variables, we also find a good consistency to the anomaly inflow described by the Atiyah-Patodi-Singer index theorem in the continuum theory. This talk is based on a work with Shoto Aoki, https://arxiv.org/abs/2203.03782 and some preliminary results.

David J.E. Marsh, King's College London

[JpDe Joint Seminar] Axion Miniclusters: Recent Progress and Open Problems

Online (Zoom)
If the Peccei Quinn symmetry is broken after inflaiton, then axions are produced by the decay of topological defects. This scenario is attractive, since the axion mass is in principle predictable from the relic density, and favours the range ~0.1-10 meV. Miniclusters offer a route to probe this scenario astrophysically. Miniclusters are formed from the overdensities in the axion field left over after the topological defects decay. I will describe recent efforts to understand the mass distribution and density profiles of miniclusters, using theory and simulation. I will also describe efforts to test the minicluster scenario using gravitational microlensing, and radio transients. Open problems surround both scenarios, related to the possible existence and survival fraction of the densest miniclusters.

Niklas Mueller, Univ. of Washington

[QCD theory Seminar] QCD meets Quantum Information Science -- Thermalization of Gauge Theories from their Entanglement Spectrum

Online (Zoom)
The possibility to simulate quantum many-body systems with digital quantum computers and analog devices is an exciting opportunity for high energy and nuclear physics. One example is Entanglement Structure (ES), first explored in the context of non-Abelian fractional quantum Hall states, but largely unexplored for gauge theories and high energy and nuclear physics. ES is crucial e.g., to understand thermalization of the quark gluon plasma in ultra-relativistic heavy ion collisions, or the structure of QCD bound states in deeply inelastic scattering (DIS) at the future Electron-Ion Collider. To illustrate this, I will show how I used Entanglement Structure and Entanglement Tomography to gain insight into quantum thermalization of strongly-coupled gauge theories, which proceeds in characteristic stages and reveals quantum phenomena remarkably similar to their classical counterparts: chaos, turbulence and universality.

Miguel Montero, Harvard University

New String Theories from Discrete Theta Angles

Online (Zoom) https://kds.kek.jp/event/44336/
Topological couplings play a prominent role in our understanding of field theories, but their role in string compactifications is much less understood. I explore an example in compactifications of type IIB string theory with sixteen supercharges, showing that they lead to previously unknown components of moduli space in nine, eight, and seven dimensions. I also explain why a similar construction fails to produce a new string theory in ten dimensions. The new components of moduli space thus constructed feature an incomplete lattice of BPS strings, which has implications for a number of Swampland constraints.

Aleksey Cherman, Univ. of Minnesota

[QCD theory Seminar] 1-form symmetry and large N QCD

Online (Zoom)
The most modern way to understand quark confinement involves the notion of `1-form symmetry’. The reason we care about quark confinement is of course because of its implications for real-world QCD, but unfortunately confinement is believed to be only an approximate concept in the real world, so it is not tied to any exact symmetries. However, confinement is supposed to become well-defined in the large N limit of QCD, and so one might expect large N QCD to have a Z_N 1-form symmetry. However, to our surprise, in recent work we found some severe obstructions to the conjecture that large N QCD has a Z_N 1-form symmetry. Our results suggest that a symmetry-based understanding of (approximate) confinement in QCD may require some further generalization of the notion of generalized global symmetries.

Tomohiro Ishizu, Kansai University

[KEK IPNS-IMSS-QUP Joint Colloquium] Empirical approaches to study aesthetic experiences -an introduction to neuroaesthetics-

Online (Zoom)
Art and aesthetic experiences enrich our daily lives. It may appear distant from the empirical sciences at first glance, but it shares similar goals and is closely related to them in that it explores perception and engages with the workings of the mind. Neuroaesthetics is a discipline that studies the relationship between brain function and aesthetic experience (e.g., beauty, ugliness, being moved, sublime) as well as between cognitive processes and artistic activity (e.g. appreciation of artworks, artistic critique, creativity) using empirical methods from cognitive neuroscience. It is an interdisciplinary field that includes researchers from psychology, neuroscience, philosophy, art, art history, to welfare engineering. Following an overview of basic cognitive neuroscience research findings on aesthetic judgements such as beauty and ugliness, I will present research on more complex aesthetic experiences beyond simple beauty, such as sorrow and the sublime. Through these, I hope to explore what beauty means to humanity from a neuroaesthetics point of view.

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