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

Session

Parallel Session 1

4 Dec 2018, 15:30

Conveners

Parallel Session 1

• Yutaka Sakamura (KEK)

Parallel Session 1

• Yutaka Sakamura (KEK)

Parallel Session 1

• Masafumi Kurachi (Keio University & KEK)

Parallel Session 1

• Masafumi Kurachi (Keio University & KEK)

Parallel Session 1

• Takahiro Terada (KEK)

Parallel Session 1

• Takahiro Terada (KEK)

31. Current status of the singlet-doublet dark matter model

Abe Tomohiro (Nagoya University)

04/12/2018, 15:30

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...

32. Modeling evolution of dark matter substructure and annihilation boost

Nagisa Hiroshima (The University of Tokyo & KEK)

04/12/2018, 15:45

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)...

33. Extended Dark Matter EFT

Valentin Tenorth (Max-Planck-Institut für Kernphysik)

04/12/2018, 16:00

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...

34. Solving core-cusp problem with Pauli exclusion principle

Haipeng An (Tsinghua University)

04/12/2018, 16:15

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.

39. Vector SIMP dark matter

Soo-Min Choi (Chung-Ang University)

04/12/2018, 16:45

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...

40. Gravitational wave generation by B-L symmetry breaking

Osamu Seto (Hokkaido University)

04/12/2018, 17:00

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.

41. Sneutrino Dark Matter meets EW SUSY inverse seesaw

Hiroyuki Ishida (NCTS)

04/12/2018, 17:15

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...

42. Gravity-mediated dark matter

Yoo-Jin Kang (Chung-Ang University)

04/12/2018, 17:30

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...

47. Fermion dark matter model with U(1) gauge symmetry

Toshinori Matsui (Korea Institute for Advanced Study)

05/12/2018, 15:30

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...

48. Dark matter models with Higgs portal to multicomponent dark sector

Takaaki Nomura (Korea Institute for Advanced Study)

05/12/2018, 15:45

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...

49. Semi-Analytic Calculation of Gravitational Wave Spectrum Induced from Primordial Curvature Perturbations

Takahiro Terada (KEK)

05/12/2018, 16:00

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...

50. Gravitational waves induced by scalar perturbations at second order as probes of the primordial power spectrum on small scales

Keisuke Inomata (ICRR, The University of Tokyo)

05/12/2018, 16:15

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...

55. Thermal Effects Induced Freeze-in Dark Matter and the Gravitational Wave

Yi-Lei Tang (Korea Institute for Advanced Study)

05/12/2018, 16:45

56. Stochastic Gravitational Waves from Particle Origin

Yong Tang (University of Tokyo)

05/12/2018, 17:00

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

57. Loop corrections to dark matter direct detection in a pseudoscalar mediator dark matter model

Motoko Fujiwara (Nagoya University)

05/12/2018, 17:15

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,...

58. QCD axion window and low-scale inflation

Fuminobu Takahashi (Tohoku University)

05/12/2018, 17:30

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...

63. Enhanced photon coupling of ALP dark matter adiabatically converted from the QCD axion

Shu-Yu Ho (Tohoku University)

06/12/2018, 15:30

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...

64. The EDGES 21 cm anomaly, and axion dark matter

Nick Houston (ITP-CAS)

06/12/2018, 15:45

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...

65. Dark photon dark matter from axion oscillations

Naoya Kitajima (Nagoya University)

06/12/2018, 16:00

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...

66. Spectral Analysis of Color Charge in Two-Prong Jets with Neural Networks

Sung Hak Lim (KEK)

06/12/2018, 16:15

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...

71. Direct measurement of the trilinear Higgs self-coupling in $e^{+}{e}^{-}\to ZH$.

Junya Nakamura (Universität Tübingen)

06/12/2018, 16:45

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 $e^{+}{e}^{-}\to ZH$, $Z\to f\overline{f}$ 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....

72. Time-information at colliders

Dong Woo Kang (Yonsei University)

06/12/2018, 17:00

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...

73. Fingerprinting models of first-order phase transitions by the synergy between collider and gravitational-wave experiments

Katsuya Hashino (Osaka University / University of Toyama)

06/12/2018, 17:15

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...

80. The LHC potential of Vector-like quark doublets

Daisuke Harada (KEK)

06/12/2018, 17:30

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