Albert Escriva, Nagoya University
Simulations of PBH formation: from the collapse of adiabatic fluctuations to the formation of vacuum bubbles
Hybrid On-site: Seminar room, Kenkyu honkan 3F Online: Zoom
Primordial Black Holes are black holes that could have been formed in the very early Universe and are arguably the most economical candidates for Dark Matter. But to make precise estimations of their abundance, it is essential to accurately know the initial conditions that could lead to their production. In this seminar, I will describe the current standard formalism and methods to accurately predict the necessary initial conditions for black hole formation, including the consequent numerical results from simulations of the collapse of adiabatic fluctuations generated during inflation. Moreover, I will present new results on the simulation of the formation of false vacuum bubbles, which can be produced if the inflaton becomes trapped during inflation. These localized bubbles will eventually end up forming black holes, also called baby Universes.
Csaba Csaki, Cornell University
Exploring the dynamics of gauge theories via AMSB
Hybrid On-site: Seminar room, Kenkyu honkan 3F Online:(Zoom) https://kds.kek.jp/event/46187/
Finding the vacuum structure and the low energy effective Lagrangian of strongly coupled gauge theories is one of the important unsolved questions in particle physics. Within supersymmetric (SUSY) theories many of these questions have been largely resolved in the 1990’s following the work of Seiberg and others, however so far we have not been able to convincingly connect these results to their non-supersymmetric counterparts. Recently Murayama proposed to use anomaly mediated supersymmetry breaking (AMSB) to introduce the SUSY breaking terms which allows finding results consistent with the qualitative expectations for the structure of the non-SUSY theories. In this talk I first show how what the resulting phase structure of the QCD-like theories obtained from perturbing SUSY QCD via AMSB is, and that the expected vauca with chiral symmetry breaking are present for any number of flavors F< 3N at least as local minima. I then discuss the resulting chiral Lagrangian for the light Goldstone bosons in these models, and examine the large N limit of the eta' mass generation mechanism. We confirm Witten's picture of several branches of vacua as a function of the theta parameters for fixed number of flavors. However, for F~N we find that in some situations the vacuum energy as a function of theta might be smooth without any phase transitions, corresponding to an instanton generated potential. If time allows I will also comment on applying AMSB to find novel vacua of chiral gauge theories as well as monopole condensation as the origin of confinement for the SO(N) series.
Tilo Wettig, University of Regensburg
Induced QCD
Hybrid On-site: Seminar room, Kenkyu honkan 3F Online:(Zoom) We explore an alternative discretization of continuum SU($N_c$) Yang-Mills theory on a Euclidean spacetime lattice, originally introduced by Budzcies and Zirnbauer. In this discretization the self-interactions of the gauge field are induced by a path integral over $N_b$ auxiliary boson fields, which are coupled linearly to the gauge field. The main progress compared to earlier approaches is that $N_b$ can be as small as $N_c$. We show analytically and numerically that the continuum limit of the new discretization reproduces Yang-Mills theory
We explore an alternative discretization of continuum SU($N_c$) Yang-Mills theory on a Euclidean spacetime lattice, originally introduced by Budzcies and Zirnbauer. In this discretization the self-interactions of the gauge field are induced by a path integral over $N_b$ auxiliary boson fields, which are coupled linearly to the gauge field. The main progress compared to earlier approaches is that $N_b$ can be as small as $N_c$. We show analytically and numerically that the continuum limit of the new discretization reproduces Yang-Mills theory
and perform a perturbative calculation to match the bare parameter of the induced gauge theory to the standard lattice coupling. We also explore the possibility to integrate out the gauge fields to arrive at a dual formulation of lattice QCD.
Michael E. Peskin, SLAC
Thinking about Particle Physics at 10 TeV and above
Hybrid On-site: Seminar room, Kenkyu honkan 3F Online: (Zoom) https://kds.kek.jp/event/46186/
Particle physicists have become interested in accelerators much more powerful than the LHC, probing energy scales 10 times higher or more. This idea stimulates many questions for which we do not yet know the answers. These questions cover all areas of particle physics from accelerators to theory: (1) What is the motivation for experiments at the 10 TeV scale? Do we really expect to find something beyond the Standard Model? What are the important targets for experiment? (2) How will we do experiments at 10 TeV? Can we simply evolve current experimental concepts? (3) What accelerator technologies will take us to 10 TeV? At this moment, different groups propose proton colliders such as SPPC, muon colliders, and electron and photon colliders. All of these approaches have significant challenges. How close are we to solving them? I do not have good answers to any of these questions, but I will give my perspective.
Rafał Masełek, Warsaw University
Prospects for detecting long-lived particles at the Large Hadron Collider
Hybrid On-site: Seminar room, Kenkyu honkan 3F Online:(Zoom)
The detection of the Higgs boson in 2012 raised hopes for rapid discovery of Physics Beyond the Standard Model at the LHC, however, the search for New Physics turned out to be much more difficult than anticipated. The lack of a positive result led to a growing interest in previously unexplored exotic signatures, e.g. long-lived particles. In the talk, I will discuss different search strategies for long-lived particles at the LHC. Special emphasis will be put on the prospects for the detection of long-lived particles in the MoEDAL experiment, which had been primarily designed to search for magnetic monopoles, but can also be utilised to detect semi-stable charged particles. Prospects for the detection of long-lived particles at the end of Run 3 and HL-LHC phases will be presented, and a comparison between different search strategies in MoEDAL, ATLAS and CMS experiments will be made.
Shi Chen, Univ. of Tokyo
[QCD theory Seminar] Solitonic symmetry beyond homotopy groups
Online(Zoom)
Solitonic symmetry is believed to be classified by homotopy groups, but I will point out a more sophisticated algebraic structure. I shall focus on a concrete QFT, the 4d CP^1 model, and demonstrate that π_3 (CP^1) = Z does not lead to a U(1) 0-form solitonic symmetry. Actually, the invertible 0-form solitonic symmetry is a Z_2 which comes from Ω^spin_3 (CP^1) = Z_2. The complete 0-form solitonic symmetry is a non-invertible symmetry generated by 3d spin TQFTs.
Xu-Hui Jiang, HKUST
Testing Lepton Flavor Universality at Future Lepton Colliders
Hybrid On-site: Seminar room, Kenkyu honkan 3F Online:(Zoom)
As one of the hypothetical principles in the Standard Model (SM), lepton flavor universality (LFU) should be tested with a precision as high as possible such that the physics violating this principle can be fully examined. The run of $Z$ factory at a future $e^+e^-$ collider such as CEPC or FCC-$ee$ provides a great opportunity to perform this task because of the large statistics and high reconstruction efficiencies for $b$-hadrons at $Z$ pole. In this paper, we present a systematic study on the LFU test in the future $Z$ factories. The goal is three-fold. Firstly, we study the sensitivities of measuring the LFU-violating observables of $b\to c \tau \nu$, {\it i.e.}, $R_{J/\psi}$, $R_{D_s}$, $R_{D_s^\ast}$ and $R_{\Lambda_c}$, where $\tau$ decays muonically. For this purpose, we develop the strategies for event reconstruction, based on the track information significantly. Secondly, we explore the sensitivity robustness against detector performance and its potential improvement with the message of event shape or beyond the $b$-hadron decays. A picture is drawn on the variation of analysis sensitivities with the detector tracking resolution and soft photon detectability, and the impact of Fox-Wolfram moments is studied on the measurement of relevant flavor events. Finally, we interpret the projected sensitivities in the SM effective field theory, by combining the LFU tests of $b\to c \tau \nu$ and the measurements of $b\to s \tau^+\tau^-$ and $b\to s \bar{\nu} \nu$. We show that the limits on the LFU-violating energy scale can be pushed up to $\sim \mathcal{O} (10)$~TeV for $\lesssim \mathcal O(1)$ Wilson coefficients at Tera-$Z$.
Goro Ishiki, University of Tsukuba
On the existence of the NS5-brane limit of the plane wave matrix model
Hybrid On-site: Seminar room, Kenkyu honkan 3F Online:(Zoom)
We consider a double scaling limit of the plane wave matrix model (PWMM), in which the gravity dual geometry of PWMM reduces to a class of spherical NS5-brane solutions. We identify the form of the scaling limit for the dual geometry of PWMM around a general vacuum and then translate the limit into the field theoretic language. We also show that the limit indeed exists at least in a certain planar 1/4-BPS sector of PWMM by using the localization computation analytically. In addition, we employ the hybrid Monte Carlo method to compute the matrix integral obtained by the localization method, near the parameter region where the supergravity approximation is valid. Our numerical results, which are considered to be the first computation of quantum loop correction to the Lin-Maldacena geometry, suggest that the double scaling limit exists beyond the planar sector.
Priyanka Lamba, Warsaw University
Quantum information and CP measurement in "$H \rightarrow \tau^+ \tau^- $" at future lepton colliders
Hybrid On-site: Seminar room, Kenkyu honkan 3F Online:(Zoom)
We introduce a methodology and investigate the feasibility of measuring quantum properties of tau lepton pairs in the H→τ+τ− decay at future lepton colliders. In particular, observation of entanglement, steerability and violation of Bell inequalities are examined for the ILC and FCC-ee. We find that detecting quantum correlation crucially relies on precise reconstruction of the tau leptons rest frame and a simple kinematics reconstruction does not suffice due to the finite energy resolution of the colliding beams and detectors. To correct for energy mismeasurements, a log-likelihood method is developed that incorporates the information of impact parameters of tau lepton decays. We demonstrate that an accurate measurement of quantum properties is possible with this method. As a by-product, we show that a novel model-independent test of CP violation can be performed and the CP-phase of Hττ interaction can be constrained with an accuracy comparable to dedicated analyses, i.e., up to 7.9∘ and 5.4∘ at ILC and FCC-ee, respectively.
Rajan Gupta, Los Alamos National Laboratory
The nucleon structure and contributions of novel CP violating interactions to the neutron electric dipole moment
Hybrid On-site: Seminar room, Kenkyu honkan 3F Online: Zoom
