380 citations · 2.4k across the 61 of their papers we have counts for
21 papers · 1 filter
Anapole Moment of Majorana Fermions and Implications for Direct Detection of Neutralino Dark Matter
Alejandro Ibarra, Merlin Reichard, Ryo Nagai
For Majorana fermions the anapole moment is the only allowed electromagnetic multipole moment. In this work we calculate the anapole moment induced at one-loop by the Yukawa and ga…
Electroweak phase transition in the nearly aligned Higgs effective field theory
Shinya Kanemura, Ryo Nagai, Masanori Tanaka
We investigate the strongly first-order electroweak phase transition using an effective field theoretical approach. The standard effective field theory with finite number truncatio…
A new Higgs effective field theory and the new no-lose theorem
Shinya Kanemura, Ryo Nagai
Non-decoupling effects of heavy new particles cannot be described by the standard effective field theory with finite truncation of higher dimensional operators. We propose a new ef…
CP-Violation in a Composite 2-Higgs Doublet Model
Stefania De Curtis, Stefano Moretti, Ryo Nagai +1
We study CP-Violation (CPV) in a Composite 2-Higgs Doublet Model (C2HDM) based on the global symmetry breaking , wherein the strong sector is modeled by…
Scalar and fermion on-shell amplitudes in generalized Higgs effective field theory
Ryo Nagai, Masaharu Tanabashi, Koji Tsumura +1
Beyond standard model (BSM) particles should be included in effective field theory in order to compute the scattering amplitudes involving these extra particles. We formulate an ex…
Direct detection of vector dark matter through electromagnetic multipoles
Junji Hisano, Alejandro Ibarra, Ryo Nagai
Dark matter particles, even if they are electrically neutral, could interact with the Standard Model particles via their electromagnetic multipole moments. In this paper, we focus…
Lepton flavor violations in SUSY models for muon with right-handed neutrinos
Ryo Nagai, Norimi Yokozaki
We consider supersymmetric (SUSY) models for the muon anomaly without flavor violating masses at the tree-level. The models can avoid LHC constraints and the vacuum stability…
Oscillating Composite Asymmetric Dark Matter
Masahiro Ibe, Shin Kobayashi, Ryo Nagai +1
The asymmetric dark matter (ADM) scenario can solve the coincidence problem between the baryon and the dark matter (DM) abundance when the DM mass is of GeV. In the…
Renormalization Effects on Electric Dipole Moments in Electroweakly Interacting Massive Particle Models
Takumi Kuwahara
The extended models of the standard model with a single Majorana fermion could be realized as the low-energy effective theory of the well-motivated ultraviolet models. We study the…
Symmetry and geometry in generalized Higgs effective field theory -- Finiteness of oblique corrections v.s. perturbative unitarity
Ryo Nagai, Masaharu Tanabashi, Koji Tsumura +1
We formulate a generalization of Higgs effective field theory (HEFT) including arbitrary number of extra neutral and charged Higgs bosons (generalized HEFT, GHEFT) to describe non-…
Renormalization Effects on Electric Dipole Moments in Electroweakly Interacting Massive Particle Models
Wataru Kuramoto, Takumi Kuwahara, Ryo Nagai
We study the renormalization effects on electric dipole moments in the models with new electroweakly interacting massive fermions. The electric dipole moments are generated by the…
Search for steady point-like sources in the astrophysical muon neutrino flux with 8 years of IceCube data
IceCube Collaboration, M. G. Aartsen, M. Ackermann +325
The IceCube Collaboration has observed a high-energy astrophysical neutrino flux and recently found evidence for neutrino emission from the blazar TXS 0506+056. These results open…
Singlet Dirac Fermion Dark Matter with Mediators at Loop
Junji Hisano, Ryo Nagai, Natsumi Nagata
We study the phenomenology of singlet Dirac fermion dark matter in the simplified models where the dark matter interacts with the Standard Model particles at loop-level with the he…
Heavy Gravitino from Dynamical Generation of Right-Handed Neutrino Mass Scale, and Gravitational Waves
Ryo Nagai, Fuminobu Takahashi, Norimi Yokozaki
The absence of supersymmetric particles at the weak scale is a puzzle if supersymmetry solves the gauge hierarchy problem. We show that, if the right-handed neutrino masses arise f…
Model independent evaluation of the Wilson coefficient of the Weinberg operator in QCD
Tomohiro Abe, Junji Hisano, Ryo Nagai
We derive a Wilson coefficient of a CP-violating purely gluonic dimension-6 operator called the Weinberg operator () generated by a scalar and two fermions at the two-…
Light Higgsino and Gluino in -invariant Direct Gauge Mediation
Norimi Yokozaki, Ryo Nagai
We provide a simple solution to the - problem in the "-invariant direct gauge mediation model". With the solution, the Higgsino and gluino are predicted to be light as $…
Classification of simple heavy vector triplet models
Tomohiro Abe, Ryo Nagai
We investigate decay modes of spin-1 heavy vector bosons () from the viewpoint of perturbative unitarity in a model-independent manner. Perturbative unitarity requires some rel…
Unitarity sum rules, three site moose model, and the ATLAS 2 TeV diboson anomalies
Tomohiro Abe, Ryo Nagai, Shohei Okawa +1
We investigate interpretations for the ATLAS 2 TeV diboson anomalies. The roles of the unitarity sum rules, which ensure the perturbativity of the longitudinal vector boson sc…
Tree level unitarity and finiteness of electroweak oblique corrections
Ryo Nagai
We study perturbative unitarity and electroweak oblique corrections in the electroweak symmetry breaking models including an arbitrary number of neutral Higgs bosons. Requiring the…
Effective Theories for Dark Matter Nucleon Scattering
Junji Hisano, Ryo Nagai, Natsumi Nagata
We reformulate the calculation of the dark matter-nucleon scattering cross sections based on the method of effective field theories. We assume that the scatterings are induced by t…
Does unitarity imply finiteness of electroweak oblique corrections at one-loop? - constraining extra neutral Higgs bosons -
Ryo Nagai, Masaharu Tanabashi, Koji Tsumura
Introducing arbitrary number of neutral Higgs bosons in the electroweak symmetry breaking sector, we derive a set of conditions among Higgs couplings which need to be satisfied to…