We study the compatibility of the unitarity bound and the 8TeV LHC on the effective theory of the scalar dark matter. In several signals of effective interactions, mono-jet with missing energy events are studied. We found that, at least, if the dark
matter mass is about 800GeV or heavier, contributions of events violating the unitarity are not negligible. The unitarity conditions in the 14TeV LHC are also calculated.
The perturbative unitarity bound is studied in the monojet process at LHC. The production of the dark matter is described by the low-energy effective theory. The analysis of the dark matter signal is not validated, if the unitarity condition is viola
ted. It is shown that the current LHC analysis the effective theory breaks down, at least, when the dark matter is lighter than O(100) GeV. Future prospects for $sqrt{s}$ = 14 TeV are also discussed. The result is independent of physics in high energy scales.
We study the perturbative unitarity bound given by dimension six derivative interactions consisting of Higgs doublets. These operators emerge from kinetic terms of composite Higgs models or integrating out heavy particles that interact with Higgs dou
blets. They lead to new phenomena beyond the Standard Model. One of characteristic contributions by derivative interactions appear in vector boson scattering processes. Longitudinal modes of massive vector bosons can be regarded as Nambu Goldstone bosons eaten by each vector field with the equivalence theorem. Since their effects become larger and larger as the collision energy of vector bosons increases, vector boson scattering processes become important in a high energy region around the TeV scale. On the other hand, in such a high energy region, we have to take the unitarity of amplitudes into account. We have obtained the unitarity condition in terms of the parameter included in the effective Lagrangian for one Higgs doublet models. Applying it to some of models, we have found that contributions of derivative interactions are not so large enough to clearly discriminate them from the Standard Model ones. We also study it in two Higgs doublet models. Because they are too complex to obtain the bound in the general effective Lagrangian, we have calculated it in explicit models. These analyses tell us highly model dependence of the perturbative unitarity bounds.
We derive the general structure of dimension-six derivative interactions in the N Higgs doublet models, where Higgs fields arise as pseudo Nambu-Goldstone modes of a strongly interacting sector. We show that there are several relations among the dime
nsion-six operators, and therefore the number of independent operators decreases compared with models on which only SU(2)_L x U(1)_Y invariance is imposed. As an explicit example, we derive scattering amplitudes of longitudinal gauge bosons and Higgs bosons at high energy on models involving two Higgs doublets, and compare them with the amplitudes in the case of one Higgs doublet.
A uniformly accelerated charged particle feels the vacuum as thermally excited and fluctuates around the classical trajectory. Then we may expect additional radiation besides the Larmor radiation. It is called Unruh radiation. In this report, we revi
ew the calculation of the Unruh radiation with an emphasis on the interference effect between the vacuum fluctuation and the radiation from the fluctuating motion. Our calculation is based on a stochastic treatment of the particle under a uniform acceleration. The basics of the stochastic equation are reviewed in another report in the same proceeding. In this report, we mainly discuss the radiation and the interference effect.
An accelerated particle sees the Minkowski vacuum as thermally excited, which is called the Unruh effect. Due to an interaction with the thermal bath, the particle moves stochastically like the Brownian motion in a heat bath. It has been discussed th
at the accelerated charged particle may emit extra radiation (the Unruh radiation) besides the Larmor radiation, and experiments are under planning to detect such radiation by using ultrahigh intensity lasers. There are, however, counterarguments that the radiation is canceled by an interference effect between the vacuum fluctuation and the radiation from the fluctuating motion. In this reports, we review our recent analysis on the issue of the Unruh radiation. In this report, we particularly consider the thermalization of an accelerated particle in the scalar QED, and derive the relaxation time of the thermalization.
Lepton flavor violation in tau and mu processes is studied in the littlest Higgs model with T-parity. We consider various asymmetries defined in polarized tau and mu decays. Correlations among branching ratios and asymmetries are shown in the followi
ng lepton flavor violation processes: mu+ --> e+ gamma, mu+ --> e+ e+ e-, mu- A --> e- A (A = Al, Ti, Au and Pb), tau+ --> mu+ gamma, tau+ --> mu+ mu+ mu-, tau+ --> mu+ e+ e-, tau+ --> mu+ P (P = pi0, eta and eta), tau+ --> mu+ V (V = rho0, omega and phi), tau+ --> e+ gamma, tau+ --> e+ e+ e-, tau+ --> e+ mu+ mu-, tau+ --> e+ P, tau+ --> e+ V, tau+ --> mu+ mu+ e- and tau+ --> e+ e+ mu-. It is shown that large parity asymmetries and time-reversal asymmetries are allowed in mu+ --> e+ e+ e-. For tau lepton flavor violation processes, sizable asymmetries are possible reflecting characteristic chirality structure of lepton flavor violating interactions in this model.
An accelerated particle sees the Minkowski vacuum as thermally excited, and the particle moves stochastically due to an interaction with the thermal bath. This interaction fluctuates the particles transverse momenta like the Brownian motion in a heat
bath. Because of this fluctuating motion, it has been discussed that the accelerated charged particle emits extra radiation (the Unruh radiation) in addition to the classical Larmor radiation, and experiments are under planning to detect such radiation by using ultrahigh intensity lasers constructed in near future. There are, however, counterarguments that the radiation is canceled by an interference effect between the vacuum fluctuation and the fluctuating motion. In fact, in the case of an internal detector where the Heisenberg equation of motion can be solved exactly, there is no additional radiation after the thermalization is completed. In this paper, we revisit the issue in the case of an accelerated charged particle in the scalar-field analog of QED. We prove the equipartition theorem of transverse momenta by investigating a stochastic motion of the particle, and show that the Unruh radiation is partially canceled by an interference effect.
