KEK-PH Lectures and Workshops 2021


"KEK-PH lectures and workshops" is a form of KEK-PH workshop series at the time of Covid-19.

The annual KEK Theory Meeting on Particle Physics Phenomenology (KEK-PH) covers many topics in Particle Physics and Cosmology, from the Standard Model and models beyond it to particle cosmology and astrophysics. At the time of Covid-19, the KEK theory center is organizing an on-line lecture and workshop series, "KEK-PH lectures and workshops 2021."

The 5th KEK-PH on "Jet Physics"

In the search for new physics at the LHC experiment, jet is often produced from heavy particle decays. By studying the jet structure, we can reconstruct particles with high momentum, such as W, Z, top, and H, and increase the sensitivity to new physics. In "KEK-PH Jet Physics", we will discuss recent theoretical developments, the latest data from the ATLAS and CMS experiments, and the expected sensitivity at the HL-LHC from both theoretical and experimental perspectives.
Invited talks
Nov. 30th (Tue.)
16:15-17:00:  Prof. Takuya Nobe (ICEPP, Tokyo), "Jet physics with ATLAS"
17:00-18:00:  Prof. Gavin Salam (Oxford), "Jets through the LHC era"
Dec. 1st (Wed.)
10:00-10:45: Prof. Cristina Mantilla (FermiLab), "Boosted jet physics in CMS" 


The 4th KEK-PH on "New Ideas in Particle Physics"

We are now preparing a workshop on "New ideas in particle physics," on Nov. 16 and 17. This time, it is a joint workshop with Florida State University (co-organizer: Kosaku Tobioka). The topics cover cosmological solutions to the naturalness problems, swampland conjectures, as well as quantum gravity effects on low energy physics.


Invited talks

First day:
16th (Tue.), Nov. 16:00-19:15 (JST)

  • Michael Geller (Tel Aviv U.), "Crunching Naturalness" 
  • Raffaele D'Agnolo (IPhT, Saclay), "Aspects of Cosmological Selection of the Weak Scale"
  • Gia Dvali (Munich U., ASC and Munich, Max Planck Inst.), "S-matrix exclusion of de Sitter landscape, and naturalness"
  • Matthew McCullough (CERN), "Gegenbauer Goldstones"

Second day:
17th (Wed.), Nov. 9:00-12:30 (JST)

  • Surjeet Rajendran (Johns Hopkins U.), "A Causal Framework for Non Linear Quantum Mechanics"
  • Anson Hook (Maryland U.), "Solving the naturalness puzzle using old ideas"
  • Yuta Hamada (Harvard U.), "Brane Probes, Finiteness and Distance Conjecture"
  • Tom Rudelius (UC, Berkeley), "Consequences of No Global Symmetries in Quantum Gravity"

Registration dead line:  

15th (Mon.) Nov. 18:00 (JST)

Zoom link will be sent to the registered e-mail address.

Grant-in-Aid for Scientific Research on Innovative Areas (18H05542), Japan
Scientific Research A (19H00689), Japan
Scientific Research B (21H01086), Japan

The 3rd KEK-PH + 1st KEK-Cosmo joint workshop on "Primordial Black Holes"

Convener(s): Kazunori Kohri and Kyohei Mukaida (KEK/Theory)


Invited talks

First invited talk:
19th (Tue.), Oct. 16:00-17:30 (JST):

Dr. Gabriele Franciolini (Geneva U), "Primordial Black Holes and Gravitational Wave Observations"

Second invited talk:
20th (Wed.), Oct. 16:00-17:30 (JST): 

Dr.  Christian Byrnes (Sussex U), "Primordial black holes as a LIGO-Virgo and dark matter candidate"

Zoom link will be sent to the registered e-mail address.

Short talks

19th (Tue.), Oct. 13:30-15:30: 

13:30 - 13:55: Marcos Flores (UCLA), "Primordial Black Holes from Long-Range Scalar Forces and Scalar Radiative Cooling"

14:00 - 14:25: Yuichiro Tada (Nagoya U), "Primordial black holes in peak theory with a non-Gaussian tail"

14:30 - 14:55: Tomohiro Harada (Rikkyo U), "Spins of primordial black holes formed in the radiation-dominated phase of the universe: first-order effect"

15:00 - 15:25: Qianhang Ding (HKUST), "Ultrahigh-energy Gamma Rays and Gravitational Waves from Primordial Exotic Stellar Bubbles"

Registration deadlines:

28th (Tue.),  Sep. 17:00 (JST): to apply for a short talk
18th (Mon.), Oct. 17:00 (JST): only for your participation


2nd KEK-PH on "Next Generation Accelerators"


Invited talks

First talk:
June 23 16:00-17:30: Prof. Mitsuhiro Yoshida (Accelerator Laboratory, KEK), "
Future laser and beam driven high gradient accelerator technology"

Registration dead line: June 21 (Mon.)  June 22 (Tue.) 17:00(JST)

Second talk:
June 30 16:00-17:30: Prof.
Daniel Schulte (CERN), "Muon Collider"

Registration dead line: June 29 (Tue.) 17:00(JST)

Zoom link will be sent to the registered e-mail address.

1st KEK-PH on "Muon g-2"


Invited talks

May 11 17:00-18:30: Dr. Massimo Passera (INFN, Padua), "Muon g-2 and Δα connection"

May 19 17:00-18:30: Prof. Christoph Lehner (Regensburg U. and Brookhaven Natl. Lab.), "Consistency of the hadronic vacuum polarization between lattice QCD and the R-ratio"

Organizers: Motoi Endo, Amon Furuichi, Toru Goto, Yu Hamada, Takahisa Igata, Ryuichiro Kitano, Kazunori Kohri, Takahiko Matsubara, Ryutaro Matsudo, Satoshi Mishima, Kyohei Mukaida, Mihoko M. Nojiri, Hajime Otsuka, Yutaka Sakamura, Kengo Shimada, Hiromasa Takaura, Yuko Urakawa

KEK-PH Jet Physics
  • Ahmed Hammad
  • Aoto Tanaka
  • Atsuya Niki
  • Cendikia Abdi
  • Chul Kim
  • Dan Kondo
  • Dong Woo Kang
  • Fathiyya Izzatun Az Zahra
  • Haruka Asada
  • Haruki Takahashi
  • Hiromasa TAKAURA
  • Hirotsugu Fujii
  • Jihun Kim
  • Junichi Tanaka
  • Junichiro Kawamura
  • Jurina Nakajima
  • Katsumasa Ikematsu
  • Katsuo Tokushuku
  • Kazunori Kohri
  • Keiichi Watanabe
  • Kengo Shimada
  • Kentarou Mawatari
  • Koichi Hattori
  • Kunihiro Nagano
  • Lakmin Wickremasinghe
  • Masahiro Kuze
  • Michihisa Takeuchi
  • Mihoko Nojiri
  • Minuk Choi
  • Motoi ENDO
  • Peiwen Wu
  • Pyungwon Ko
  • Ryu Sawada
  • Satoshi Mishima
  • Shun-ichiro Koh
  • shunyu yao
  • So Chigusa
  • SooJin Lee
  • Suyong Choi
  • Takeshi Chikamatsu
  • Tetsufumi Hirano
  • Toshi Sumida
  • Won Jun
  • Yasuki Tachibana
  • Yuta Okazaki
  • Yutaro Iiyama
  • Yuuka Kanakubo
    • 17:00 18:30
      KEK-PH Muon g-2
      Convener: Motoi ENDO
      • 17:00
        Muon g-2 and Δα connection 1h 30m

        The Muon g-2 experiment at Fermilab has recently confirmed Brookhaven's earlier measurement of the muon anomalous magnetic moment aμ. This new result increases the discrepancy Δaμ with the Standard Model (SM) prediction and strengthens its "new physics" interpretation as well as the quest for its underlying origin. In this talk I will review the SM prediction of the muon g-2, focusing on some of the latest developments, and discuss the connection of the discrepancy Δaμ to precision electroweak predictions via their common dependence on hadronic vacuum polarization effects.

        Speaker: Dr Massimo Passera (INFN, Padua)
    • 17:00 18:30
      KEK-PH Muon g-2
      Convener: Motoi ENDO
      • 17:00
        Consistency of the hadronic vacuum polarization between lattice QCD and the R-ratio 1h 30m

        I will review the current status of data-driven R-ratio as well as lattice QCD determinations of the hadronic vacuum polarization. I will then discuss universality tests within the lattice QCD community and the consistency with data-driven results based on the R-ratio. The talk will also present expected progress in the coming years.

        Speaker: Prof. Christoph Lehner (Regensburg U. and Brookhaven Natl. Lab.)
    • 16:00 17:30
      KEK-PH Next Generation Accelerators
      • 16:00
        Future laser and beam driven high gradient accelerator technology 1h 30m

        Recent high gradient accelerator technologies will be introduced. Most popular high gradient accelerator is the laser plasma wakefield accelerator and it reaches up to 100 GV/m level. However it is currently low repetition rate and difficult for the cascading acceleration. On the other hand, there are another accelerator technologies to realize the high repetition and the cascading acceleration based on the THz wave. The main issue for the THz accelerator is the efficient THz generation driven by high power laser or the electron beam. Further recent high power laser technologies are also introduced.

        Speaker: Prof. Mitsuhiro Yoshida (Accelerator Laboratory, KEK)
    • 16:00 17:30
      KEK-PH Next Generation Accelerators
      • 16:00
        Muon Collider 1h 30m

        A muon collider provides a unique path to a high-energy, high-luminosity lepton collider that combines precision measurements and discovery potential. The talk will introduce the scheme and highlight some key challenges. It will also introduce the new collaboration that plans to develop the concept.

        Speaker: Prof. Daniel Schulte (CERN)
    • 13:00 16:00
      The KEK-PH + KEK-Cosmo joint workshop on "Primordial Black Holes": Short talks
      Convener: Dr Kazunori Kohri (KEK)
      • 13:30
        Primordial Black Holes from Long-Range Scalar Forces and Scalar Radiative Cooling 30m

        Primordial black holes (PBHs) are a natural consequence of long-range scalar forces in the early Universe. These forces can lead to the formation of halos of heavy particles, Q-balls or oscillons even during the radiation dominated era. This same force removes energy and angular momentum from virialized systems via scalar radiation, leading to the subsequent formation of black holes. We will discuss two scenarios which result in the formation of PBHs. First, we consider heavy fermions interacting via a light scalar mediator. This scenario relates the mass of the dark-sector particles to the masses and abundance of dark matter PBHs in a way that can explain why dark matter and ordinary matter have similar mass densities. Second, we consider interactions among SUSY Q-balls. The mass and abundance of PBHs in this scenario are naturally explained by the SUSY breaking scale. Lastly, we will comment on the expected PBH spins from this formation mechanism in comparison to other earlier models.

        Speaker: Mr Marcos Flores (UCLA)
      • 14:00
        Primordial black holes in peak theory with a non-Gaussian tail 30m

        In this work, we update the peak theory for the estimation of the primordial black hole (PBH) abundance,
        particularly by implementing the critical behavior in the estimation of the PBH mass and employing the averaged compaction function for the PBH formation criterion to relax the profile dependence.
        We apply our peak theory to a specific non-Gaussian feature called the exponential tail, which is characteristic in ultra slow-roll models of inflation. With this type of non-Gaussianity, the probability of a large perturbation is not suppressed by the Gaussian factor but decays only exponentially, so the PBH abundance is expected to be much enhanced.
        Not only do we confirm this enhancement even compared to the case of the corresponding nonlinearity parameter $f_\mathrm{NL}=5/2$, but also we find that the resultant PBH mass spectrum has a characteristic maximal mass which is not seen in the simple Press--Schechter approach.

        Speaker: Dr Yuichiro Tada (Nagoya U)
      • 14:30
        Spins of primordial black holes formed in the radiation-dominated phase of the universe: first-order effect 30m

        The standard deviation of the initial values of the nondimensional Kerr parameter a∗ of primordial black holes (PBHs) formed in the radiation-dominated phase of the universe is estimated to the first order of perturbation for the narrow power spectrum. Evaluating the angular momentum at turn around based on linearly extrapolated transfer functions and peak theory, we obtain the expression. This implies that for M≃MH, where MH is the horizon mass at the horizon entry, the higher the probability of the PBH formation, the larger the standard deviation of the spins, while PBHs of M≪MH formed through near-critical collapse may have larger spins than those of M≃MH. In comparison to the previous estimate, the new estimate has the explicit dependence on the ratio M/MH and no direct dependence on the current dark matter density. On the other hand, it suggests that the first-order effect can be numerically comparable to the second-order one.

        Speaker: Prof. Tomohiro Harada (Rikkyo U)
      • 15:00
        Ultrahigh-energy Gamma Rays and Gravitational Waves from Primordial Exotic Stellar Bubbles 30m

        We put forward a novel class of exotic celestial objects that can be produced through phase transitions occurred in the primordial Universe. These objects appear as bubbles of stellar sizes and can be dominated by primordial black holes (PBHs). We report that, due to the processes of Hawking radiation and binary evolution of PBHs inside these stellar bubbles, both electromagnetic and gravitational radiations can be emitted that are featured on the gamma-ray spectra and stochastic gravitational waves (GWs). Our results reveal that, depending on the mass distribution, the exotic stellar bubbles consisting of PBHs provide not only a decent fit for the ultrahigh-energy gamma-ray spectrum reported by the recent LHAASO experiment, but also predict GW signals that are expected to be tested by the forthcoming GW surveys.

        Speaker: Mr Qianhang Ding (HKUST)
      • 15:30
        Break 30m
    • 16:00 18:00
      The KEK-PH + KEK-Cosmo joint workshop on "Primordial Black Holes": 1st Invited Talk
      Convener: Dr Mukaida Kyohei (KEK)
      • 16:00
        Primordial Black Holes and Gravitational Wave Observations 2h

        Primordial Black Holes might comprise a significant fraction of dark matter in the Universe and can give rise to observable signatures at current and future gravitational wave experiments. First, we review the PBH model and discuss how accretion and clustering may affect the properties of PBH binaries. Second, we confront the PBH model with LIGO/Virgo data showing its upsides and shortcomings, by also including state-of-the-art astrophysical models in a multi-population inference. Finally, we discuss how 3G detectors, such as Einstein Telescope and Cosmic Explorer, may be able to discover a PBH population by searching for high redshift merger events.

        Speaker: Dr Gabriele Franciolini (Geneva U)
    • 16:00 18:00
      The KEK-PH + KEK-Cosmo joint workshop on "Primordial Black Holes": 2nd Invited Talk
      Convener: Kazunori KOHRI (KEK/Theory)
      • 16:00
        Primordial black holes as a LIGO-Virgo and dark matter candidate 2h

        Although black holes can be the remnants of dead stars, it is also possible that some are primordial. Such primordial black holes are the unique dark matter candidate which is not a new type of particle, and they could also explain some of the unexpected properties of the black hole mergers that LIGO and Virgo have detected. I will summarise the evidence and (fine-tuning) challenges behind this claim, including a new Bayesian model comparison between astrophysical and primordial black holes.
        I will also discuss the interesting coincidence of scales between the LIGO events, Chandrasekhar limit and the horizon mass during the QCD transition in the early universe, and the wavelength of gravitational waves on which NANOGrav may (potentially) have detected a stochastic gravitational wave background.

        Speaker: Dr Christian Byrnes (Sussex U)
    • 16:00 19:15
      KEK-PH New Ideas in Particle Physics: 1st day
      • 16:00
        Crunching Naturalness 45m
        Speaker: Michael Geller (Tel Aviv U.)
      • 16:45
        Aspects of Cosmological Selection of the Weak Scale 45m
        Speaker: Raffaele D'Agnolo (IPhT, Saclay)
      • 17:30
        Break 15m
      • 17:45
        S-matrix exclusion of de Sitter landscape, and naturalness 45m
        Speaker: Gia Dvali (Munich U., ASC and Munich, Max Planck Inst.)
      • 18:30
        Gegenbauer Goldstones 45m
        Speaker: Matthew McCullough (CERN)
    • 09:00 12:30
      KEK-PH New Ideas in Particle Physics: 2nd day
      • 09:00
        A Causal Framework for Non Linear Quantum Mechanics 1h
        Speaker: Surjeet Rajendran (Johns Hopkins U.)
      • 10:00
        Solving the naturalness puzzle using old ideas 45m
        Speaker: Anson Hook (Maryland U.)
      • 10:45
        Break 15m
      • 11:00
        Brane Probes, Finiteness and Distance Conjecture 45m
        Speaker: Yuta Hamada (Harvard U.)
      • 11:45
        Consequences of No Global Symmetries in Quantum Gravity 45m
        Speaker: Tom Rudelius (UC, Berkeley)
    • 16:15 18:00
      KEK-PH Jet Physics
      • 16:15
        Jet physics with ATLAS 45m

        New physics searches using jet substructure are actively performed at the LHC era. There are several new techniques with ATLAS to extract the substructure information more precisely. A new particle-flow algorithm, unified-flow objects (UFOs), is recently developed to improve the resolution of the substructure variables. On top of that, to identify boosted W/Z/top/H decaying to hadrons, as well as unknown new particles which form the characteristic jet substructure, some new approaches are introduced, using some machine-learning techniques and/or new substructure representatives e.g. Lund-plane variables. The modeling of the jet substructure is an important key to improve the sensitivity. In this talk, I will summarize recent developments of the ATLAS jet substructure, and the status of the new physics searches using it.

      • 17:00
        Jets through the LHC era 1h

        In this talk I will give a personal view of some of the major theoretical advances that have been made in jet physics through the LHC era so far. Topics that I will touch on will include the development of infrared safe jet finders, essential for quantitative interpretation of LHC data; the development of the field of jet substructure to identify hadronic decays of boosted electroweak bosons; and progress towards the use of complete event information in interpreting the underlying scattering dynamics of high-energy collisions.

    • 10:00 10:45
      KEK-PH Jet Physics
      • 10:00
        Boosted jet physics in CMS 45m

        Many measurements and searches at the Large Hadron Collider need to identify highly boosted particles that decay to hadronic final states. The decay products of these particles will be closely collimated and reconstructed into one single large-radius jet. One can then use jet substructure and deep learning approaches to learn information about the radiation pattern inside the jet and mitigate combinatorial backgrounds. For example, graph neural networks can be trained to take the unordered set of jet constituent particles as inputs and infer attributes of the jet. These jet tagging methods are then calibrated to reflect their tagging efficiency in data and the uncertainties on the calibration will vary depending on the complexity of the final state. In this talk, I will review the latest jet tagging techniques in CMS, their calibration methods and its usage in searches for boosted heavy resonances with 13 TeV LHC data.