KEK Theory Meeting on Particle Physics Phenomenology (KEK-PH2018 winter) and 3rd KIAS-NCTS-KEK workshop on Particle Physics Phenomenology

4 Dec 2018, 08:00 → 7 Dec 2018, 18:00 Asia/Tokyo

 

The annual Theory Meeting on Particle Physics Phenomenology (KEK-­PH2018) together with the 3rd KIAS-NCTS-KEK Joint Workshop will be held at KEK between December 4 - 7, 2018. This meeting covers many topics in Particle Physics and Cosmology, from the Standard Model and models beyond the Standard Model to particle cosmology and astrophysics. We plan to discuss recent developments in modeling Physics Beyond the Standard Model with their phenomenological aspects and also learn about the latest results and status of various ongoing and planned experiments.

The meeting includes talks by invited speakers and short talks by participants. All the talks will be given in English. We aim to provide an opportunity, not only for experts but also for master/Ph.D course students, to learn recent developments in particle physics phenomenology and to activate intensive discussions. The participants will also have the opportunity to present their work through poster presentations.

 

Registration is open now! Deadline: October 31, 2018.

A limited amount of support for local expenses (travel within Japan and KEK dormitory expenses) is available. Unfortunately, we cannot cover International travel.

Late registration is available with no financial support. The deadline for requesting VISA letter and local support is September 30, 2018.

 

Invited Speakers (KEK-PH):

==Theory==

• Csaba Csaki (Cornell U.)
• Raffaele D'Agnolo (SLAC) 
• Jose Ramon Espinosa (Barcelona)
• Patrick Fox (Fermilab)
• Gino Isidori (Zurich U.)
• Joerg Jaeckel (ITP, Heidelberg)
• Joachim Kopp (Mainz U.)
• David McKeen (TRIUMF)
• Maxim Pospelov (Perimeter Inst.)
• Matthew Schwartz (Harvard U.) 

==Expt==

• Toshio Namba  (Tokyo U.)
• Yoshiyuki Onuki (Tokyo U.)
• Kirill Prokofiev (HKUST)

 

Invited Speakers (KIAS-NCTS-KEK Joint workshop):

 

From Japan:

• Natsumi Nagata (Tokyo U.)
• Toshifumi Noumi (Kobe U.)
• Motoo Suzuki (ICRR)
• Hiromasa Takaura (Kyushu U.)

 

From Korea: 

• Sang Hui Ihm (Pusan National U.)
• Sunghoon Jung (Seoul National U.)
• Doojin Kim (Arizona U.)
• Jeonghan Kim (Kansas U.)
• Minho Son (KAIST)

 

From Taiwan: 

• Chuan-Ren Chen (NTNU)
• Gang Li (NTU)
• Kin-Wang NG (Academia Sinica)
• Martin Spinrath (National Tsing Hua University)
• Yue-Lin Sming Tsai (Academia Sinica)
• Kimiko Yamashita (NTHU)

 

 

 

 

Local Organizers:

• Amit Chakraborty                        
• Yohei Ema
• Motoi Endo                                  
• Toru Goto
• Ryuichiro Kitano                           
• Kazunori Kohri 
• Masafumi Kurachi 
• Sung Hak Lim 
• Satoshi Mishima 
• Mihoko M. Nojiri
• Daisuke Nomura 
• Yutaka Sakamura
• Yoshihiro Shigekami 
• Takahiro Terada 
• Daiki Ueda

External Organizers:

• Koichi Hamaguchi (U. Tokyo)                        
• Junji Hisano (Nagoya U.)
• Shinya Kanemura (Osaka U.)                                  
• Shigeki Matsumoto (Kavli IPMU)
• Fuminobu Takahashi (Tohoku U.)                          
• Koji Tsumura (Kyoto U.)

Organizers (KIAS-NCTS-KEK Joint workshop): 

  Korea:

• Pyungwon Ko (KIAS)  
• Eung Jin Chun (KIAS)

  Taiwan:

• Kingman Cheung (NTHU)
• Tzu-Chiang Yuan (Academia Sinica)

 

The KEK-­PH 2018 winter workshop is supported by the KEK theory center research project, "BSM in high energy and high intensity frontier," and MEXT Grant-in-aid for Scientific Research on Innovative Areas, "Neutrino physics and the origin of the Universe (25105011)," and "Exploration of Particle Physics and Cosmology with Neutrinos (18H05542)."

Group Photo DSC_4021p.jpg

Tuesday, 4 December

09:00 → 09:30 Registration

09:30 → 10:30 Plenary Session

Convener: Mihoko Nojiri (KEK)

09:30 Cosmological Signatures of the SM Vacuum Instability

Speaker: Jose Ramon Espinosa (ICREA/IFAE Barcelona and CERN)

Slides Espinosa_KEK2018.pdf

10:00 Birefringent DE/DM and CMB B-modes

We discuss CMB B-mode polarization induced by dark energy or dark matter birefringence.

Speaker: Kin-Wang Ng (Academia Sinica)

Slides KEK18_Ng.pdf

10:30 → 11:00 Tea Break

11:00 → 12:00 Plenary Session

Convener: Mihoko Nojiri (KEK)

11:00 Higgs boson pair production at HL-LHC and HL-100 Collider

We perform the most up-to-date comprehensive signal-background analysis for Higgs-pair production in HH ->b ̄b gamma gamma channel at the HL-LHC and HL-100 TeV hadron collider, with the goal of probing the self-coupling of the Higgs boson.

Speaker: Kingman Cheung (National Tsing Hua University)

11:30 Primordial non-Gaussianities as a particle collider

The energy scale of inflation could be as high as 1014 GeV, hence it is a phenomenon at the highest energy scale we may explore. Primordial non-Gaussianities can then be thought of as a 1014 GeV collider (dubbed the cosmological collider), which may be used to probe new particles at the inflationary scale. In this talk I will review recent progress in the cosmological collider program including our own works. In particular I will discuss how to read of the mass and spin of new particles from non-Gaussianities.

Speaker: Toshifumi Noumi (Kobe University)

Slides Noumi.pdf

12:00 → 13:30 Lunch

13:30 → 15:00 Plenary Session

Convener: Kazunori Kohiri (KEK)

13:30 Infrared frontier of fundamental physics

Speaker: Maxim Pospelov (University of Victoria / Perimeter Institute)

14:00 The impact of EDGES 21-cm data on WIMP dark matter interactions

The recently announced results on the 21-cm absorption spectrum by the EDGES experiment can place very stringent limits on dark matter annihilation cross sections. We properly take into account the heating energy released from dark matter annihilation from the radiation epoch to the 21-cm observation redshifts in the radiative transfer to compute the evolution of the gas temperature. Our results show that the global 21-cm absorption profile is a powerful cosmological probe of the dark matter interactions. For dark matter annihilating into electron-positron pairs, the EDGES results give a more stringent upper limit than the PLANCK result on the annihilation cross section at the lower dark matter mass region.

Speaker: Yue-Lin Tsai (Academia Sinica)

Slides 2018-KEK-21cm-Tsai.pdf

14:30 LHC Searches for Kaluza-Klein Graviton Decaying into SM/DM Particles

We study the phenomenology of a massive graviton G with universal and non-universal (top-philic) couplings to the Standard Model (SM) particles. Such a particle can arise as a warped Kaluza-Klein graviton from a framework of the Randall-Sundrum extra-dimension model. We also consider simplified dark matter models where a dark matter candidate couples to the SM particles via a G mediator. We study constraints on the model parameter space from the current LHC data. Eur. Phys. J. C 77, no. 5, 326 (2017) (arXiv: 1701.07008) JHEP 1810, 046 (2018) (arXiv1807.09643)

Speaker: Kimiko Yamashita (National Tsing Hua University)

15:00 → 15:30 Tea Break

15:30 → 16:30 Parallel Session 1

Convener: Yutaka Sakamura (KEK)

15:30 Current status of the singlet-doublet dark matter model

Weakly interacting massive particle (WIMP) has been a popular candidate of dark matter (DM) in our universe. However, many WIMP models are now severely constrained from the DM direct detection experiments. The singlet-doublet model is one of the models that can evade the strong constraints from the DM direct detection experiments. The model predicts interesting phenomenology due to the CP violation in the dark sector. In this talk, I will discuss the current status of the singlet-doublet dark matter model from viewpoints of DM indirect detection experiments, LHC constraints, and the stability of the Higgs potential.

Speaker: Abe Tomohiro (Nagoya University)

Slides Tomohiro-Abe_KEK-PH2018-winter.pdf

15:45 Modeling evolution of dark matter substructure and annihilation boost

We study evolution of dark matter substructures, especially how they lose the mass and change density profile after they fall in gravitational potential of larger host halos. We develop an analytical prescription that models the subhalo mass evolution and calibrate it to results of N-body numerical simulations of various scales from very small (Earth size) to large (galaxies to clusters) halos. We then combine the results with halo accretion histories, and calculate the subhalo mass function that is physically motivated down to Earth-mass scales. Our results --- valid for arbitrary host masses and redshifts --- show reasonable agreement with those of numerical simulations at resolved scales. Our analytical model also enables self-consistent calculations of the boost factor of dark matter annhilation, which we find to increase from tens of percent at the smallest (Earth) and intermediate (dwarfs) masses to a factor of several at galaxy size, and to become as large as a factor of ∼10 for the largest halos (clusters) at small redshifts. Our analytical approach can accommodate substructures in the subhalos (sub-subhalos) in a consistent framework, which we find to give up to a factor of a few enhancement to the annihilation boost. Presence of the subhalos enhances the intensity of the isotropic gamma-ray background by a factor of a few, and as the result, the measurement by Fermi Large Area Telescope excludes the annihilation cross section greater than ∼4×10−26 cm3 s−1 for dark matter masses up to ∼200 GeV.

Speaker: Nagisa Hiroshima (The University of Tokyo & KEK)

Slides KEK-PH_hirosima.pdf

16:00 Extended Dark Matter EFT

We present a new framework in the language of effective field theory (EFT) to describe Dark Matter and combine limits from experimental searches from nuclear ("Direct Detection") to LHC energies. To improve the high energy-validity of conventional DM EFTs we add a dynamical (pseudo-) scalar serving as mediator to the dark sector, represented by a fermion (or scalar), where richer new-physics sectors can be consistently included via higher-dimensional operators. The model is formulated in a gauge-invariant way and allows to confront classical Dark Matter observables with measurements of the Higgs sector. Interestingly the leading effects originate at dimension-five, allowing to capture them with a rather small set of parameters. We present constraints on the parameter space arising from collider mono-X searches, the relic abundace, indirect and direct detection experiments. The "model-independent" approach allows to apply the results to different UV-complete models such as 2HDM+a, extended fermion sectors, the NMSSM and composite mediators.

Speaker: Valentin Tenorth (Max-Planck-Institut für Kernphysik)

Slides KEK-PH18_Tenorth.pdf

16:15 Solving core-cusp problem with Pauli exclusion principle

I will present a dark matter model in which the dark matter particle is a fermion with mass about 200 eV. In this mass range the Fermi pressure can solve the core-cusp problem of the dwarf galaxies and the Lyman-alpha constraints can be avoided by cooling and scattering in the dark sector.

Speaker: Haipeng An (Tsinghua University)

15:30 → 16:30 Parallel Session 2

Convener: Daisuke Nomura (KEK)

15:30 Vacuum decay rates in the standard model and beyond

The electroweak vacuum is not absolutely stable in the standard model and various models beyond the standard model. This is due to an appearance of another deeper vacuum, into which the electroweak vacuum can decay. We have performed one-loop calculations of the decay rates in various models including the standard model. In this talk, I explain current status of our analysis on models beyond the standard model.

Speaker: Yutaro Shoji (KMI, Nagoya U.)

Slides yshoji-vacuum.pdf

15:45 Lower Bound on the Bounce Action

To calculate lifetime of false vacuum, we have to estimate bounce action. We derive a lower bound on the bounce action without solving equation of motion of scalar field explicitly. This technique is useful to analyze models with large number of scalar fields.

Speaker: Ryosuke Sato (DESY)

Slides bounce.pdf

16:00 De Sitter swampland conjecture and cosmological applications

Speaker: Hiroki Matsui (Tohoku University)

Slides KEK-Swampland_2018v5.pdf

16:15 Leptogenesis via active neutrino oscillation

The possibility of generating the baryon asymmetry of the Universe via flavor oscillation in the early Universe is discussed. After the inflation, leptons are born in some states, travel in the medium, and are eventually projected onto flavor eigenstates due to the scattering via the Yukawa interactions. By using the Lagrangian of the Standard Model with the Majorana neutrino mass terms, llHH, we follow the time evolution of the density matrices of the leptons in this very first stage of the Universe and show that the CP violation in the flavor oscillation can explain the baryon asymmetry of the Universe. In the scenario where the reheating is caused by the decay of the inflaton into the Higgs bosons, the baryon asymmetry is generated by the CP phases in the Pontecorvo-Maki-Nakagawa-Sakata matrix and thus can be tested by the low energy neutrino experiments.

Speaker: Wen Yin (KAIST)

Slides KEKPH.pdf

16:30 → 16:45 Break

16:45 → 17:45 Parallel Session 1

Convener: Yutaka Sakamura (KEK)

16:45 Vector SIMP dark matter

Strongly Interacting Massive Particles (SIMPs) have recently been proposed as light thermal dark matter relics. Here we consider an explicit realization of the SIMP mechanism in the form of vector SIMPs arising from an SU(2)X hidden gauge theory, where the accidental custodial symmetry protects the stability of the dark matter. We propose several ways of equilibrating the dark and visible sectors in this setup. In particular, we show that a light dark Higgs portal can maintain thermal equilibrium between the two sectors, as can a massive dark vector portal with its generalized Chern-Simons couplings to the vector SIMPs, all while remaining consistent with experimental constraints.

Speaker: Soo-Min Choi (Chung-Ang University)

Slides 181204_SM_Choi_v2.pdf

17:00 Gravitational wave generation by B-L symmetry breaking

B-L gauge symmetry is a promising extension of the standard model and its breaking plays an important role for neutrino masses. We show that the first order phase transition of the B-L gauge symmetry breaking could generate a large amplitude of stochastic gravitational waves radiation.

Speaker: Osamu Seto (Hokkaido University)

Slides kekph2018(Seto).pdf

17:15 Sneutrino Dark Matter meets EW SUSY inverse seesaw

In this paper we study sneutrino dark matter in a recently proposed supersymmetric electroweak-scale inverse seesaw model, in which the majority of the sneutrino dark matter particle is a mixture of the right-handed sneutrino and the singlet field. The scalar field X responsible for the generation of neutrino masses can simultaneously play a crucial role for sneutrino annihilation in the early Universe via the pseudoscalar mediator into neutrinos. We focus here on the dominant annihilation channels and provide all the formulas together with analytic estimates in order to identify the relevant parameters.

Speaker: Hiroyuki Ishida (NCTS)

Slides Joint-ISHIDA.pdf

17:30 Gravity-mediated dark matter

We consider a Kaluza-Klein (KK) massive spin-2 graviton as the mediator between dark matter (DM) and Standard Model (SM) particles. KK graviton can mediate the annihilations of dark matter into SM particles and it can be searched for at the LHC through monophoton and dijet channels, etc. In some benchmark models for massive gravitons, we discuss the DM-nucleon spin-independent elastic scattering and show that the parameter space for the DM relic density is consistent with current direct/indirect detection and collider searches.

Speaker: Yoo-Jin Kang (Chung-Ang University)

Slides yoojin_KEK_1812.pdf

16:45 → 17:45 Parallel Session 2

Convener: Daisuke Nomura (KEK)

16:45 Indirect search for CP-violation in the Higgs sector by the precision test of Higgs couplings

Although the discovered Higgs boson appears to favor the standard model, the structure of the Higgs sector is not clear yet. For instance, we can consider some extension of the Higgs sector while we keep consistency in the collider experiments. In particular, CP-violating Higgs sector is motivated by the baryon number asymmetry of the Universe. In this talk, we discuss how effects of the CP-violation in the Higgs sector can be observed indirectly. We focus on two Higgs doublet model (2HDM) with the CP-violation, and then we analyze indirect effects of the CP-violation on couplings of the discovered Higgs boson and discuss the precision test using the future colliders. As a result, we find that by measuring the Higgs boson couplings very precisely we are able to distinguish the CP-violating 2HDM from the CP-conserving one. This talk is based on [M. Aoki, K. Hashino, D. Kaneko, S. Kanemura and M. Kubota, arXiv:1808.08770 [hep-ph]].

Speaker: Mitsunori Kubota (Osaka University)

Slides KEK-PH2018_Kubota.pdf

17:00 Revisiting Flavor and CP Violation in Supersymmetric SU(5) with Right-Handed Neutrinos

We revisit the minimal supersymmetric SU(5) grand unified theory with three right-handed neutrinos in which universality conditions for soft-supersymmetry breaking parameters are imposed at the Planck scale. If the Majorana masses for the neutrinos are around 10^15 GeV, large mixing angles and phases in the neutrino sector lead to flavor-violation and CP-violation in the right-handed down squark and left-handed slepton sectors. Since the observed Higgs boson mass and the proton decay constraints indicate sfermions have masses larger than a few TeV, flavor and CP constraints are less restrictive. We explore the constraints on models with a universal soft-supersymmetry breaking input parameters coming from proton stability, electric dipole moments, μ→ eγ decay, and the Higgs mass observed at the LHC. Regions compatible with all constraints can be found if non-zero A-terms are taken.

Speaker: Takumi Kuwahara (Institute for Basic Science)

17:15 Non-perturbative effects of loop-induced mixing: Majorana fields and CP violation

In the loop-induced mixing of multiple flavors of fields, there exist non-perturbative effects which produce phenomenolgical effects which have been improperly considered so far especially when the mass differences among flavors are small. In this talk, I will discuss how to correctly handle such effects and their phenomenological implications especially in connection with CP violation. I will explicitly discuss only Majorana fields, but similar effects in cases of scalar and Dirac fields will also be discussed briefly.

Speaker: Chang-Hun Lee (NCTS)

Slides NPEShort.pdf

17:30 CP violating mode of the stoponium decay into Zh

We show that a novel decay mode Zh of the bound state of stop-anti-stop pair in the ground state may have a significant branching ratio if the CP violating mixing appears in the stop sector, even after we apply the stringent constraint from the measurement of the electric dipole moment (EDM) of the electron. We show that the branching ratio can be as large as 10% in some parameter space that it may be detectable at the LHC.

Speaker: Po Yen Tseng

Slides talk.pdf

Wednesday, 5 December

09:00 → 10:30 Plenary Session

Convener: Motoi Endo (KEK)

09:00 Old and recent puzzles in Flavour Physics

A series of recent results in B physics seem to indicate a coherent pattern of deviations from the Standard Model predictions. I will show how these “anomalies” could naturally be linked to the old, and still open, puzzle of quark and lepton masses, and I will discuss attempts to solve both these problems in terms of physics beyond the Standard Model.

Speaker: Gino Isidori (University of Zurich)

Slides KEK2.pdf

09:30 Sterile Neutrinos - Whence, Where, and Whither?

We discuss some of the manifold ways in which sterile neutrinos (SM singlet fermions mixing with neutrinos) affect particle physics, astrophysics, and cosmology. In the first part of the talk, we focus on eV-scale sterile neutrinos as a possible explanation for various short-baseline oscillation anomalies. In the second part, we discuss several ways in which sterile neutrinos can affect dark matter physics and early Universe cosmology.

Speaker: Joachim Kopp (CERN)

Slides sterile-nu.key sterile-nu.pdf

10:00 Direct Detection Prospects for the Cosmic Neutrino Background

Speaker: Martin Spinrath (National Tsing Hua University)

Slides KEK_Spinrath.pdf

10:30 → 11:00 Tea Break

11:00 → 12:00 Plenary Session

Convener: Pyungwon Ko (Korea Institute for Advanced Study)

11:00 Limit on the Axion Decay Constant from the Cooling Neutron Star in Cassiopeia A

The observed rapid cooling of the neutron star (NS) located at the center of the supernova remnant Cassiopeia A (Cas A) can be explained in the minimal NS cooling scenario. This consequence may be changed if there exists an extra cooling source, such as axion emission. In this work, we study the Cas A NS cooling in the presence of axion emission, taking account of the temperature evolution in the whole life of the Cas A NS. We obtain a lower limit on the axion decay constant, f_a > (5-7) x 10^8 GeV, if the star has an envelope with a thin carbon layer. This is as strong as existing limits imposed by other astrophysical observations such as SN1987A.

Speaker: Natsumi Nagata (University of Tokyo)

Slides 20181205.pdf

11:30 Realistic axion model with "Gauged" PQ mechanism

The Peccei-Quinn (PQ) symmetry may be badly broken by the quantum gravity effect. I suggest the general prescription to protect the PQ symmetry by the gauge symmetry. Then, I mention its potential cosmological problem due to extra fermions which are introduced to cancel the self and the gravitational anomalies. Finally, I show the simple model with the B-L gauge symmetry, where the PQ symmetry can be sufficiently protected without adding extra fermions.

Speaker: Motoo Suzuki (ICRR)

Slides KEK-PH2018.pdf

12:00 → 13:30 Lunch

13:30 → 15:00 Plenary Session

Convener: Csaba Csaki (Cornell University)

13:30 Recent results from the LHC

Speaker: Kirill Prokofiev (Hong Kong University of Science and Technology)

Slides KEK18.pdf

14:30 Resolving phenomenological problems with SIMP models with dark vector resonances

Speaker: Pyungwon Ko (Korea Institute for Advanced Study)

Slides KEK2018_pko.pdf

15:00 → 15:30 Poster Session & Tea Break

15:00 Gauge invariant regularization for perturbative chiral gauge theory

We propose a novel gauge-invariant regularization for the perturbative chiral gauge theory. Our method consists of the two ingredients: use of the domain-wall fermion to describe a chiral fermion with Pauli-Villars regulators and application of the dimensional regularization only to the gauge field. This regularization is implemented in the Lagrangian level, unlike other gauge-invariant regularizations (eg. the covariant regularizations). We show that the Abelian (fermion number) anomaly is reproduced correctly in this formulation.

Speaker: Yu Hamada (Kyoto University)

15:00 Leptoquarks for B-meson anomalies and dark matter

The LHCb experiment has recently provided several new measurements to test the lepton flavor universality in the Standard Model (SM) and confirmed some of the prevailing anomalies from the B-meson decays in BaBar and/or Belle experiments. We consider the setup where scalar leptoquarks or extra U(1) gauge bosons have flavor-dependent couplings to the SM. In this work, we discuss the flavor structure for quarks and leptons and various constraints on the model and propose a natural candidate for dark matter.

Speaker: Tae Gyu Ro (Chung-Ang University)

15:00 MeV-scale reheating temperature and thermalization of three active neutrinos by radiative and hadronic decays of massive particles

We study a possible minimum value of reheating temperature in terms of Big-Bang Nucleosynthesis by considering both radiative and hadronic decays of massive particles. In the current study, neutrino oscillation and neutrino self-interactions are also taken into account. We adopt updated observational bounds on the primordial abundance of light elements. We obtain the lower bound on the reheating temperature of 4 MeV -- 5 MeV depending on the mass and hadronic branching ratio of the massive particles. Compared with cases with 100% radiative decay, we find that the change due to hadronic decays on the lower bound is of the order of O(10)%, whereas those of neutrino oscillation and neutrino self-interaction are of the order of O(1)%.

Speaker: Takuya Hasegawa (SOKENDAI (KEK))

15:00 Non-Abelian Schwinger Pair Production in Topologically Non-Trivial Background Fields

Schwinger pair production is examined in SU(2) (SL(2,C)) background fields through the worldline instanton method, whose non-Abelian equivalent stems from Wong’s equations. The role of group complexification for pair production in non-Abelian fields is elucidated. The gauge group winding number is compared and contrasted with the worldline instanton winding number, related to number of produced pairs, for special topologically non-trivial background gauge configurations.

Speaker: Patrick Copinger (Tokyo University)

15:00 Resonant leptogenesis at TeV-scale and neutrinoless double beta decay

We investigate a resonant leptogenesis by quasi-degenerate right-handed neutrinos which masses are TeV scale. At TeV scale, the yield of the baryon asymmetry depends on the phases of PMNS matrix thanks to the flavor effect. In this talk, we show how the yield of the baryon asymmetry correlates with the Dirac-type CP phase and the Majorana-type CP phase. In addition, we discuss the impact on the neutrinoless double beta decay from the observed baryon asymmetry. We present the predicted range of the effective neutrino mass in neutrinoless double beta decay in order to account for the baryon asymmetry.

Speaker: Takahiro Yoshida (Niigata University)

15:00 Symmetry and geometry in generalized Higgs sector

We formulate a generalization of Higgs effective field theory (HEFT) to include arbitrary number of extra neutral and charged Higgs bosons. The relationship between the finiteness of the electroweak oblique corrections and the perturbative unitarity of the scattering amplitudes involving the Higgs bosons and the longitudinal gauge bosons is clarified in this setup: we verify that once the tree level unitarity is ensured, then oblique parameters' one-loop finiteness is automatically guaranteed. We also obtain formulas which relates the coefficients of the S and U parameter divergences with the scattering amplitudes which can be measured in future collider experiments. These relations give us new prospects when we formulate the strategy of model-building.

Speaker: Yoshiki Uchida (Nagoya University)

15:30 → 16:30 Parallel Session 1

Convener: Masafumi Kurachi (Keio University & KEK)

15:30 Fermion dark matter model with U(1) gauge symmetry

We investigate models with a gauge symmetry which is spontaneously broken by an additional Higgs field. In this framework, dark matter (DM) is stabilized by the remnant discrete symmetry originated from the gauge symmetry. We classify such a scenario in cases with the local U(1) symmetry and the global U(1) symmetry. In order to discuss how can we distinguish each case, we here focus on a scenario for fermion DM. We search parameter regions considering various constraints such as searches for DM, second Higgs boson, and dark photon or dark radiation. One of the experimental interests, we expect to explain the gamma-ray excess as the DM indirect detection in the local model. This talk is based on a collaboration with Seungwon Baek, Pyungwon Ko and Wan-Il Park.

Speaker: Toshinori Matsui (Korea Institute for Advanced Study)

15:45 Dark matter models with Higgs portal to multicomponent dark sector

We consider multi-component dark sector, where the heavier dark particles have stronger couplings to the scalar mediators and may be copiously produced at colliders. These heavier particles then decay to the dark matter (DM) plus standard model (SM) particles outside the detectors, thus behaving as DM imposters at colliders. In a such case, there is no longer tight correlation between the DM direct detection and collider searches, thereby widely opening a new window for DM model building and phenomenology. We construct two explicit models, one for fermionic DM and the other for vector DM, and study various DM phenomenolgy including collider signatures.

Speaker: Takaaki Nomura (Korea Institute for Advanced Study)

16:00 Semi-Analytic Calculation of Gravitational Wave Spectrum Induced from Primordial Curvature Perturbations

Whether or not the primordial gravitational wave (GW) produced during inflation is sufficiently strong to be observable, GWs are necessarily produced from the primordial curvature perturbations in the second order of perturbation. The induced GWs can be enhanced by curvature perturbations enhanced at small scales or by the presence of matter-dominated stages of the cosmological history, both of which are motivated in primordial black hole scenarios to explain dark matter or the LIGO/Virgo event rate. We analytically calculate the integral in the expression of the power spectrum of the induced GWs which is a universal part independent of the primordial spectrum. This makes the subsequent numerical integrals significantly easy. In simple cases, we derive fully analytic formulae for the induced GW spectrum.

Speaker: Takahiro Terada (KEK)

Slides 2ndGW_KEK-PH2018w_Terada.pdf

16:15 Gravitational waves induced by scalar perturbations at second order as probes of the primordial power spectrum on small scales

Compared to curvature perturbations on large scales ($>1$Mpc), those on small scales ($<1$Mpc) are not severely constrained. In this talk, we revisit the issue of probing small-scale primordial perturbations using gravitational waves (GWs), based on the fact that, when large-amplitude primordial perturbations on small scales exist, GWs are induced at second order, and these induced GWs can be probed by both existing and planned gravitational-wave detectors. We use updated, more precise formulae for these induced GWs, and include a variety of gravitational-wave detectors, to report existing and expected limits on the small-scale primordial spectrum. We also discuss how an early matter-dominated era changes these limits on curvature perturbations.

Speaker: Keisuke Inomata (ICRR, The University of Tokyo)

Slides kek_ph_2018_inomata.pdf

15:30 → 16:30 Parallel Session 2

Convener: Toru Goto (KEK)

15:30 Sbottoms as probes to MSSM with Nonholomorphic Soft Interactions

Presence of nonholomorphic soft SUSY breaking terms is known to be a possibility in the popular setup of the Minimal Supersymmetric Standard Model (MSSM). It has been shown that such a scenario known as NonHolomorphic Supersymmetric Standard Model (NHSSM) could remain ‘natural’ (i.e., not fine-tuned) even in the presence of a rather heavy higgsino-like LSP. However, it turns out that distinguishing such a scenario from the MSSM is unlikely to be an easy task, in particular at the Large Hadron Collider (LHC). In a first study of such a scenario at colliders (LHC), we explore a possible way that focuses on the sbottom phenomenology. This exploits the usual tan β-dependence (enhancement) of the bottom Yukawa coupling but reinforced/altered in the presence of non-vanishing nonholomorphic soft trilinear parameter A' for sbottom sector . For a given set of masses of the sbottom(s) and the light electroweakinos (LSP, lighter chargino etc.) which are known from experiments, the difference between the two scenarios could manifest itself via event rate in the 2b-jets + MET final state, which could be characteristically different from its MSSM expectation. Impact on the phenomenology of the stops at the LHC is also touched upon.

Speaker: Samadrita Mukherjee (Indian Association for the Cultivation of Science)

Slides Mukherjee_KEKPH2018.pdf

15:45 SUSY model for muon g-2 anomaly and dark matter, and its implications

Since constraints from LHC SUSY searches and direct detection experiments of dark matter become increasingly stringent, it becomes non-trivial task to find a SUSY model which can explain the muon g-2 anomaly and the nature of dark matter, simultaneously. In this talk, I will present a relatively simple SUSY model solving these two important issues, satisfying the LHC and other constraints. It is also shown that, although the model is free from flavor changing neutral current processes in the quark sector, lepton flavor violating processes of the muon can be seen at near future experiments when the thermal leptogenesis is responsible for the observed baryon asymmetry.

Speaker: Norimi Yokozaki (Tohoku University)

Slides kekph_2018_yokozaki.pdf

16:00 Spontaneous SUSY breaking in natural SO(10) GUT

If from natural SO(10) GUT, in which DT splitting can be realized with natural assumption in which all interactions allowed by the symmetry are introduced with O(1) coefficients, one singlet field is reduced, SUSY is spontaneously broken in meta-stable vacuum. Although gaugino masses become much smaller than sfermion masses, we discuss a few interesting phenomenological predictions of this scenario.

Speaker: Nobuhiro Maekawa (Nagoya Univ. KMI)

Slides KEKph18.pdf

16:15 Phenomenology in the model with parity symmetry

We construct an extended Standard Model (SM), motivated by the strong CP problem and the dark matter. In our model, the parity symmetry is conserved, introducing the extra gauge symmetry, $ SU(2)_R ¥times U(1)_R$. The charges of $SU(2)_R ¥times U(1)_R$ are assigned to the mirror fields in the same way as in the SM, but the chirality of the extra fermions is opposite to respect the parity symmetry. The mirror quarks are also charged under the $SU(3)_c$ in the SM, so that the strong CP problem is resolved. In this setup, the gauge symmetry in the mirror leads stable particles like proton and electron. In order to avoid the stable colored particle, we introduce some scalars that also become stable because of the gauge symmetry. In this talk, we discuss the dark matter (DM) physics assuming the lightest scalar is DM.

Speaker: Yuji Omura (KMI, Nagoya Univ.)

Slides Omura@KEKPH2018.pdf

16:30 → 16:45 Break

16:45 → 17:45 Parallel Session 1

Convener: Masafumi Kurachi (Keio University & KEK)

16:45 Thermal Effects Induced Freeze-in Dark Matter and the Gravitational Wave

Speaker: Yi-Lei Tang (Korea Institute for Advanced Study)

17:00 Stochastic Gravitational Waves from Particle Origin

This talk will be based on arXiv:1810.04975, which investigated how inflaton's gravitational decay can contribute to gravitational waves.

Speaker: Yong Tang (University of Tokyo)

Slides KEK-Tang.pdf

17:15 Loop corrections to dark matter direct detection in a pseudoscalar mediator dark matter model

If dark matter (DM) is a fermion and its interactions with the standard model particles are mediated by pseudoscalar particles, the tree-level amplitude for the DM-nucleon elastic scattering is suppressed by the momentum transfer in the non-relativistic limit. At the loop level, on the other hand, the spin-independent contribution to the cross section appears without such suppression. Thus, the loop corrections are essential to discuss the sensitivities of the direct detection experiments for the model prediction. The one-loop corrections were investigated in the previous works. However, the two-loop diagrams give the leading order contribution to the DM-gluon effective operator and have not been correctly evaluated yet. Moreover, some interaction terms which affect the scattering cross section were overlooked. In this talk, we show the cross section obtained by the improved analysis and discuss the region where the cross section becomes large.

Speaker: Motoko Fujiwara (Nagoya University)

Slides KEK-PH2018_FUJIWARA.pdf

17:30 QCD axion window and low-scale inflation

We show that the upper bound of the classical QCD axion window can be significantly relaxed for low-scale inflation. If the Gibbons-Hawking temperature during inflation is lower than the QCD scale, the initial QCD axion misalignment angle follows the Bunch-Davies distribution. The distribution is peaked at the strong CP conserving minimum if there is no other light degree of freedom contributing to the strong CP phase. As a result, the axion overproduction problem is significantly relaxed even for an axion decay constant larger than 1012GeV. We also provide concrete hilltop inflation models where the Hubble parameter during inflation is comparable to or much smaller than the QCD scale, with successful reheating taking place via perturbative decays or dissipation processes.

Speaker: Fuminobu Takahashi (Tohoku University)

16:45 → 17:45 Parallel Session 2

Convener: Toru Goto (KEK)

16:45 Neutral Naturalness and its UV realization

We will present a neutral naturalness model with emphasizing the realistic misalignment between the electroweak scale and the new physics scale, and we will discuss its Ultraviolet realization in holographic Higgs setup, which realizes the finiteness of the Higgs potential.

Speaker: Ling-Xiao Xu (Peking University)

Slides slides_KEK_xulingxiao.pdf

17:00 Composite 2 Higgs doublet model

We discuss composite 2 Higgs doublet models based on the global symmetry breaking SO(6) to SO(4)*SO(2), where 2 Higgs doublets emerge as a pseudo Nambu-Goldstone bosons. The Higgs potential is generated at one-loop level via the Coleman-Weinberg mechanism. We show that the prediction of the Higgs boson mass spectrum and couplings can be different from those in the minimal supersymmetric standard model.

Speaker: Kei Yagyu (Seikei University)

17:15 Matching renormalisable couplings between generic theories

The precise study of the Higgs boson properties -- in particular its mass and couplings -- is of the utmost importance for the investigation of BSM models with extended Higgs sectors. As New Physics currently seems to be driven to higher scales by experimental searches, the framework of Effective Field Theory becomes necessary to address the large mass hierarchies that appear in calculations. In this context, there is a growing interest for the precise matching of Higgs couplings and its automation. I will present recent work on the matching of renormalisable couplings -- in particular scalar quartic and Yukawa couplings -- between generic theories at one-loop order. I will first show how to avoid a potential loss of accuracy in the automated calculation of threshold corrections due to large logaritmic terms in both the low- and high-energy parts of the corresponding matching conditions. Then, I will discuss different possible choices of renormalisation schemes that can potentially simplify the matching procedure, focusing in particular on the treatment of mixing between scalars in these schemes. Finally, I show some examples of results, with a comparison of different schemes in a toy model, and expressions for the one-loop matching of the Higgs quartic coupling in Supersymmetric models with Dirac gauginos.

Speaker: Johannes Braathen (Osaka University)

Slides Braathen_KEK-PH2018.pdf

17:30 Machine learning with augmentation for boosting di-Higgs searches

Augmentation of invisible information with respect to many hypothetical models of background and signal processes, can highly improve the performance of the machine learning classifiers for HEP event discrimination. In this regard di-Higgs searches in the channels with multiple invisible final states, is one of the most important applications. Focusing on the di-Higgs channels with 2 bottom quarks + 0/1/2 leptons/taus + MET from bbWW and bbtautau productions, we introduce various augmentation schemes and ways to build better multi-class classifiers using deep neural networks. We conclude our study with demonstration how much the new deep learning classifiers supervised by physical augmentation, can improve the discovery potential of di-Higgs production at the LHC, and discuss on the implications for future collider study.

Speaker: Kayoung Ban (Yonsei University)

Slides KEK_PH2018_KYBAN.pdf

18:00 → 20:00 Banquet

Thursday, 6 December

09:00 → 10:30 Plenary Session

Convener: Jose Ramon Espinosa (ICREA/IFAE Barcelona and CERN)

09:00 The Inelastic Frontier at DM and Neutrino detectors

There exist well motivated models of particle dark matter which predominantly scatter inelastically off nuclei in direct detection experiments. This inelastic transition causes the DM to up-scatter in terrestrial experiments into an excited state heavier than the DM itself. The relative competitiveness of DM search experiments is governed by the upper bound on the recoil energies employed by each experiment, as well as strong sensitivity to the mass of the heaviest element in the detector. Several implications, including sizable recoil energy-dependent annual modulation, and improvements for future experiments are discussed. I will also discuss how low threshold neutrino detectors can be used to search for the de-excitation of iDM which has up scattered in the Earth.

Speaker: Patrick Fox (Fermilab)

Slides iDMFrontier.pdf

09:30 Cosmic neutrino searches as decaying dark matter detectors

The dark matter (or some of it) could exist in a form that decays to neutrinos at cosmologically late times. Proposed experiments searching for the cosmic neutrino background, such as PTOLEMY, could be sensitive to this scenario. We discuss the signals allowed at such an experiment given cosmological constraints.

Speaker: David McKeen (TRIUMF)

Slides mckeen_KEK_12_06_18.pdf

10:00 Non-canonical forth generation leptons

Speaker: Chuan-Ren Chen (National Taiwan Normal University)

Slides 4thL_KEK.pptx

10:30 → 11:00 Tea Break

11:00 → 12:00 Plenary Session

Convener: Maxim Pospelov (University of Victoria / Perimeter Institute)

11:00 Machine Learning in Particle Physics

Speaker: Matthew Schwartz (Harvard University)

Slides KEK-Pheno-Schwartz.pdf

11:30 Inelastic Boosted Dark Matter Searches at Neutrino Detectors

The search for boosted dark matter, which often arises in two-component dark matter scenarios, has received rising attention as an alternative dark matter search strategy. I will discuss phenomenology of boosted dark matter at neutrino detectors including Super/Hyper Kamiokande, focusing on the case where such boosted dark matter scatters off target material inelastically to a heavier unstable dark-sector state which further decays into visible particles in addition to visible target recoil.

Speaker: Doojin Kim (University of Arizona)

Slides Presentation_KEK_DoojinKim.pdf

12:00 → 12:10 Group Photo

12:10 → 13:30 Lunch

13:30 → 15:00 Plenary Session

Convener: Joachim Kopp (CERN)

13:30 WISP searches by Tokyo tabletop experiments group

Speaker: Toshio Namba (ICEPP, the University of Tokyo)

Slides namba-kekph.pdf

14:00 Hot Topics at Belle and Belle II

Speaker: Yoshiyuki Onuki (University of Tokyo)

Slides KEK-PH2018WinterOnukiV6.pdf

14:30 Physics Beyond Colliders - Exploring BSM Physics

Speaker: Joerg Jaeckel (ITP Heidelberg)

Slides KEK-talk-Beyond.pdf

15:00 → 15:30 Poster Session & Tea Break

15:30 → 16:30 Parallel Session 1

Convener: Takahiro Terada (KEK)

15:30 Enhanced photon coupling of ALP dark matter adiabatically converted from the QCD axion

We revisit the adiabatic conversion between the QCD axion and axion-like particle (ALP) at level crossing, which can occur in the early universe as a result of the existence of a hypothetical mass mixing. This is similar to the Mikheyev-Smirnov-Wolfenstein effect in neutrino oscillations. After refining the conditions for the adiabatic conversion to occur, we focus on a scenario where the ALP produced by the adiabatic conversion of the QCD axion explains the observed dark matter abundance. Interestingly, we find that the ALP decay constant can be much smaller than the ordinary case in which the ALP is produced by the realignment mechanism. As a consequence, the ALP-photon coupling is enhanced by a few orders of magnitude, which is advantageous for the future ALP and axion-search experiments using the ALP-photon coupling.

Speaker: Shu-Yu Ho (Tohoku University)

Slides KEK_PH_Seminar_12_06_2018_Shu_Yu_Ho.pdf

15:45 The EDGES 21 cm anomaly, and axion dark matter

Recent observations by the EDGES collaboration have energised the worldwide cosmological community by opening a first observational window into the 'cosmic dawn', when the first stars and galaxies emerged. Yet more excitingly, their findings also suggest that the primordial hydrogen gas present at that time may have been much colder than expected, possibly betraying the indirect influence of the mysterious dark matter known to invisibly permeate our Universe. We report on recent research (Phys. Rev. Lett. 121, 111301 (2018)) demonstrating that, by virtue of the ability to mediate cooling processes whilst in the condensed phase, a small amount of axion dark matter can explain these observations within the context of standard models of axions and axion-like-particles. The EDGES best-fit result favours an axion-like-particles mass in the (10, 450) meV range, which can be compressed for the QCD axion to (100, 450) meV in the absence of fine tuning. Future experiments and large scale surveys, particularly the International Axion Observatory (IAXO) and EUCLID, should have the capability to directly test this scenario.

Speaker: Nick Houston (ITP-CAS)

Slides KEK-PH_2018-houston.pdf

16:00 Dark photon dark matter from axion oscillations

We present a new mechanism for producing the correct relic abundance of dark photon dark matter over a wide range of its mass, extending down to 10−20 eV. The dark matter abundance is initially stored in an axion which is misaligned from its minimum. When the axion starts oscillating, it efficiently transfers its energy into dark photons via a tachyonic instability. If the dark photon mass is within a few orders of magnitude of the axion mass, mγ′ /ma = O(10−3 − 1), then dark photons make up the dominant form of dark matter today. We present a numerical lattice simulation for a benchmark model that explicitly realizes our mechanism. This mechanism firms up the motivation for a number of experiments searching for dark photon dark matter.

Speaker: Naoya Kitajima (Nagoya University)

16:15 Spectral Analysis of Color Charge in Two-Prong Jets with Neural Networks

We discuss signatures in the two-point correlation spectrum S2(R) on the angular scale R for identifying color charge in two-prong jets. In a two-prong jet, the radiation pattern is correlated with the color charge of originating partons and the decay topology of the jet so that we need a strategy considering those effects simultaneously. The spectral analyses with S2(R) and neural network provide us with a visual framework for studying two-prong substructure as well as color superstructure in terms of the angular scale R. Furthermore, we can design neural networks with interpretable subparts in this framework. The interpretable subparts help us understand how the prediction from the neural network came out. We show our results in the context of classification among Higgs, Sgluon, and QCD jets.

Speaker: Sung Hak Lim (KEK)

Slides JetSubstructureSpectroscopy_SungHak.pdf

15:30 → 16:30 Parallel Session 2

Convener: Satoshi Mishima (KEK)

15:30 Lattice calculation of B to D(*) semileptonic form factor and determination of |Vcb|

We report our works on calculation of exclusive B-meson decays to charmed mesons. In lattice simulation, we use the Oktay-Kronfeld action for the bottom and the charmed quark and HISQ action for the light quarks. We report how discretization error in the lattice simulation can be controlled in systematic way.

Speaker: Jaehoon Leem (Korea Institute For Advanced Study)

Slides LEEM_201812_KEK.pdf

15:45 SMEFT top-quark effects on \Delta F=2 observables

We investigate model independent top-quark corrections to ∆F = 2 processes within the framework of the Standard Model Effective Field Theory. Dimension-six ∆F = 1 operators contribute to them though renormalization group evolutions and matching conditions. We provide a complete one-loop matching formula from the top quarks for ∆F = 2 transitions. We also demonstrate these corrections on ∆MBs in the left-right symmetric model, which are compared with the conventional calculations.

Speaker: Daiki Ueda (Sokendai)

16:00 Flavon Stabilization in Models with Discrete Flavor Symmetry

We propose a simple mechanism for stabilizing flavon fields with aligned vacuum structure in models with discrete flavor symmetry. The basic idea is that flavons are stabilized by the balance between the negative soft mass and non-renormalizable terms in the potential. We explicitly discuss how our mechanism works in A4 flavor model, and show that the field content is significantly simplified. It also works as a natural solution to the cosmological domain wall problem.

Speaker: So Chigusa (University of Tokyo)

Slides SoChigusa.pdf

16:15 Test of the $R(D^{(*)})$ anomaly at the LHC

There are discrepancies between the experimental results and the Standard Model predictions, in the lepton flavor universality of the semileptonic $B$ decays: $B ¥to D^{(*)} ¥ell ¥nu$. As the new physics interpretations, new charged vector and charged scalar fields, that dominantly couple to the second and third generations, have been widely discussed. In this work, we study the signals of the new particles at the LHC, and test the interpretations via the direct search for the new resonances. In particular, we see that the $¥tau ¥nu$ resonance search at the LHC has already covered most of the parameter regions favored by the Belle and BaBar experiments. We find that the bound is already stronger than the one from the $B_c$ decay depending on the mass of charged scalar. This talk is based on arXiv:1810.05843.

Speaker: Syuhei Iguro (Nagoya University)

Slides 18_Iguro_KEKph.pdf

16:30 → 16:45 Break

16:45 → 17:45 Parallel Session 1

Convener: Takahiro Terada (KEK)

16:45 Direct measurement of the trilinear Higgs self-coupling in $e^+e^- \to ZH$.

A method to measure "directly" the trilinear Higgs self-coupling $\lambda$ in a single Higgs production process is proposed. Time-reversal-odd (T-odd) quantities in the process $e^+e^- \to ZH$, $Z \to f\bar{f}$ are computed from the absorptive part of the electroweak one-loop amplitude. They are essentially up-down asymmetries of the final fermion $f$ with respect to the $ZH$ production plane. The T-odd asymmetries directly measure $\lambda$, because the tree-level diagram for a final-state interaction between the $ZH$ contributes linearly to them.

Speaker: Junya Nakamura (Universität Tübingen)

Slides KEKPH2018-JN.pdf

17:00 Time-information at colliders

We study the kinematics of long-lived particles which decay inside the detector using precision timing information. We consider the event with two long-lived particles which decay to visible and invisible particles. We reconstruct 4-momentum of long-lived particles as well as invisible particles by solving kinematic equations with and without the timing information. Without using the timing information, the kinematic equation is only solved in very special case. But using the timing information we can solve it in general cases. With this method, we can find out more information of long-lived particles at the collider.

Speaker: Dong Woo Kang (Yonsei University)

Slides KEK_DWK.pdf

17:15 Fingerprinting models of first-order phase transitions by the synergy between collider and gravitational-wave experiments

If a first-order phase transition occurs in the early Universe, gravitational waves are produced from collisions of bubbles and subsequent plasma dynamics. Since the resulting GW spectrum reflects the underlying particle physics model, we may be able to use the gravitational-wave spectrum to explore the form of the Higgs potential. In this talk, we quantitatively discuss this possibility by adopting the Fisher matrix analysis, which is essentially a Gaussian approximation of the likelihood function, to analyze the expected constraints in future space-based interferometers for parameters of the extended models and discuss the testability of the model by the synergy between the collider and gravitational-wave experiment. This talk is based on [K. H, R. Jinno, M. Kakizaki, S. Kanemura, T. Takahashi and M. Takimoto, arXiv:1809.04994 [hep-ph]].

Speaker: Katsuya Hashino (Osaka University / University of Toyama)

Slides KEKPH_2018_winter_Katsuya.pdf

17:30 The LHC potential of Vector-like quark doublets

I will talk about the recent result of our work “The LHC potential of Vector-like quark doublets” which is arxiv:1806.01024.

Speaker: Daisuke Harada (KEK)

16:45 → 17:45 Parallel Session 2

Convener: Satoshi Mishima (KEK)

16:45 Leptoquark interpretations of B anomaly and its implications on top quark physics

Recently, various leptoquark models have been investigated in terms of interpreting the recent B meson anomalies. We study the possible implications of relevant leptoquark scenarios on the top quark observables.

Speaker: Peiwen Wu (Korea Institute For Advanced Study)

Slides PeiwenWu-RD-topFCNC.pdf

17:00 Tomography by neutrino pair beam

We consider the neutrino tomography. The idea of neutrino tomography is the imaging of the Earth ’s interior structure by using the neutrino. We assume the neutrino pair beam which has recently been proposed as neutrino source. The beam produces a large amount of neutrino and antineutrino pairs from the circulating partially stripped ions and provides the possibility to measure precisely the energy spectrum of neutrino oscillation probability together with a sufficiently large detector. It is shown that the pair beam gives a better sensitivity to probe the Earth’s crust compared with the neutrino sources at present. In addition we present a method to reconstruct a matter density profile by means of the analytic formula of the oscillation probability in which the matter effect is included perturbatively to the second order.

Speaker: Hirashi Okui (Niigata University)

Slides 20181206_KEK-PH_okui.pdf

17:15 Muon decay into an electron and a light boson in a muonic atom

The charged lepton flavor violation (CLFV) is a good probe to search for new physics beyond the standard model. If there is a neutral boson X which is lighter than muon and has CLFV interaction, a muon can decay into an electron and an X, i.e. mu-> e+X. The search for this process is expected to constraint the property of X. In this talk, we focus on a search for the rare decay of muon in a muonic atom due to some advantages. We show the general quantitative calculation for the electron spectrum of the mu->e+X in a muonic atom.

Speaker: Yuichi Uesaka (Saitama University)

Slides 20181206_uesaka.pdf

17:30 Improved analysis for lepton-nucleus CLFV scattering $\ell_{i}N \to \ell_{j}X$ by scalar interaction

We revisit charged lepton flavor violating (CLFV) scattering $\ell_{i}N \to \ell_{j}X$ mediated by scalar interaction. We point out that a new subprocess $\ell_{i}g \to \ell_{j}g$ via the effective interactions of CLFV mediator and gluon gives large contribution. Furthermore, in the light of quark number conservation, we consider quark pair-production processes $\ell_{i}g \to \ell_{j} Q \bar{Q}$ ($Q$ denotes heavy quarks) instead of $\ell_{i}Q \to \ell_{j}Q$. We discuss model discrimination by analyzing final state distributions.

Speaker: Masato Yamanaka (Kyushu Sangyo University)

Friday, 7 December

09:00 → 10:30 Plenary Session

Convener: Patrick Fox (Fermilab)

09:00 New directions for composite Higgs models

Speaker: Csaba Csaki (Cornell University)

Slides KEKDecember2018Csaki.pdf

09:30 Disorder in Model Building: from the Hierarchy Problem to Colliders

I will talk about two distinct ideas connected by the introduction in particle phenomenology of disordered systems with a large number of degrees of freedom. First I will show how freeze-in dark matter can solve the hierarchy problem. Then I will discuss how hidden sectors with a large number of new particles can hide at colliders.

Speaker: Raffaele D'Agnolo (SLAC)

Slides KEK_Dec2018.pdf

10:00 Group Theoretic Approach to Theory of Fermion Production

Speaker: Minho Son (KAIST)

Slides KEK-PH2018_SON.pdf

10:30 → 11:00 Tea Break

11:00 → 12:00 Plenary Session

Convener: Gino Isidori (University of Zurich)

11:00 Heterotic M-theory from the clockwork perspective

A continuum limit of the clockwork mechanism provides a useful picture to understand extra dimensions. The Generalized Linear Dilaton model (GLD) realizes the continuum clockwork with varying clockwork gear masses. A special point of GLD is the linear dilaton model (LD) which has been discussed from the type II little string theory. In this talk, I will discuss a possible UV completion of GLD from different types of string theory. It will be shown that the Horava-Witten theory (or Heterotic M-theory) provides a direct realization of certain types of GLD with characteristic phenomenological features. Furthermore, I will discuss the possibility that more general M-theory limit via 11D supergravity can realize LD and Randall-Sundrum (RS) points.

Speaker: Sang Hui Im (Pusan National University)

Slides KEK_SHI.pdf

11:30 Determination of alpha_s from static QCD potential with renormalon subtraction

We determine the strong coupling constant alpha_s from the static QCD potential by matching a theoretical calculation with lattice QCD computation. We adopt a new theoretical framework where we subtract the renormalon uncertainties, which limit the accuracy of perturbation theory, based on OPE. This allows us to take a considerably wider fitting range than ordinary perturbation theory, which leads to a more reliable determination. We obtain alpha_s(M_Z) with 1.3 % accuracy, which is consistent with the current PDG value.

Speaker: Hiromasa Takaura (Kyushu University)

Slides KEKPH2018-Takaura.pdf

12:00 → 13:30 Lunch

13:30 → 15:00 Plenary Session

Convener: Ryuichiro Kitano (KEK)

13:30 A Dark Horse in Search for Non-Resonant Double Higgs

We propose a novel method for measuring the triple Higgs coupling at the LHC. We choose the hh -> (b b)(l+l- MET) process, as a concrete example, which is least investigated due to huge backgrounds. The method relies on two new kinematic functions, Topness and Higgsness, which respectively characterize features of ttbar (major background) and hh events. It leads to a surprisingly high signal significance compared to existing results without employing sophisticated machine learning techniques. Our approach is applicable to different final states such as (b b)(j j l MET) and (bb)(tautau), as well as searches for other BSM particles. Reference: arXiv:1807.11498

Speaker: Jeong Han Kim (The University of Kansas)

Slides KEK_JHK.pdf

14:00 Charged scalars at the LHC

Speaker: Gang Li (National Taiwan University)

Slides 2018_charged_scalars_KEK.pdf

14:30 Probing Dark Matter at LIGO and Mid-band

Speaker: Sunghoon Jung (Seoul National University)

Slides DMatLIGO.pdf

15:00 → 15:30 Closing Remarks