セミナー

Rabin Banerjee, S N Bose National Centre for Basic Science

Unifying tunneling and anomaly based approaches for Hawking effect

Seminar Room, Kenkyu Honkan 3F
We consider the tunneling formalism, based on density matrix, and the covariant trace and diffeomorphism anomaly formalism to discuss the Hawking effect. The two approaches are connected using the notion of chirality.

Yong Tang, National Center for Theoretical Sciences

Electroweak Vacuum Stability with Neutrino and Dark Matter

Meeting Room 1 , Kenkyu Honkan 1F
Motivated by the discovery of the Standard Model (SM) Higgs mass around 125 GeV at the LHC, we study the vacuum stability and perturbativity bounds on Higgs scalar of the SM extensions including neutrinos and dark matter (DM). Guided by the SM gauge symmetry and the minimal changes in the SM Higgs potential we consider two extensions of neutrino sector (Type-I and Type-III seesaw mechanisms) and DM sector (a real scalar singlet (darkon) and minimal dark matter (MDM)) respectively. The darkon contributes positively to the $beta$ function of the Higgs quartic coupling $lambda$ and can stabilize the SM vacuum up to high scale. Similar to the top quark in the SM, the cause of instability is sensitive to the size of new Yukawa couplings between heavy neutrinos and Higgs boson, namely, the scale of seesaw mechanism. MDM and Type-III seesaw fermion triplet, two nontrivial representations of $SU(2)_{L}$ group, will bring the additional positive contributions to the gauge coupling $g_{2}$ renormalization group (RG) evolution and would also help to stabilize the electroweak vacuum up to high scale. Reference: arXiv:1202.5717

Nobuhiro Maekawa, Nagoya U

Spontaneous CP violation in E6 GUT and flavor physics

Meeting Room 1, Kenkyu Honkan 1F
It is shown that the origin of Kobayashi-Maskawa phase can be understood by spontaneous CP violation in E6 GUT with family symmetry and moreover, it can solve the SUSY CP problem, especially the strong constraint for the effective SUSY type sfermion mass spectrum from CEDM can be satisfied in a non-trivial way. The naive problem for massless mu neutrino can be solved by considering the higher dimensional operators which are allowed by the symmetry. As the result, realistic neutrino masses iand mixings including large theta13 can be obtained. In the end of this talk, we will comment on the 125 GeV Higgs for this scenario.

Yasutaka Taniguchi, U Tsukuba

Cluster correlations in largely deformed states of nuclei

Seminar Room, Kenkyu Honkan 3F
Nuclear structure changes drastically by low-excitation energies. We discuss deformations and clustering effects, which play important roles in nuclear structures. Nuclei have various structures such as coexistence of various rotational bands, prolate-oblate shape coexistence, multi-cluster states, and so on. In order to understand those structures, both of deformations and clustering should be taken into account.

Laszlo Feher, Institute for Particle and Nuclear Physics, Wigner RCP, HAS

The Ruijsenaars self-duality map as a mapping class symplectomorphism

Seminar Room, Kenkyu Honkan 3F
We explain that the self-duality symplectomorphism of the completely integrable compactified trigonometric Ruijsenaars-Schneider system arises from the natural action of the mapping class group on the moduli space of flat SU(n) connections on the one-holed torus. The talk is based on joint work with C. Klimcik reviewed in arXiv:1203.3300.

Andrew G. Akeroyd, University of Southampton

Phenomenology of the Higgs Triplet Model at the LHC

Meeting Room 1, Kenkyu Honkan 1F
The Higgs Triplet Model is a model of neutrino mass generation which predicts the existence of a doubly charged scalar and a singly charged scalar. Such particles could enhance the branching ratio of a neutral Higgs boson decaying to two photons, a channel which has been observed recently at the LHC. I also discuss the phenomenology of the doubly/singly charged scalars at the LHC, as well as summarise their ongoing searches.

森田辰弥, 東京大

量子系の弱い測定による弱値について

Seminar Room, Kenkyu Honkan 3F
量子系の測定において量子系の始状態と終状態を指定して定まる弱値が注目さ れている。本講演では弱値とその測定である弱測定の手法、及び実験的に有用 とされる弱値の測定値に対する増幅効果について紹介する。また量子力学の基 礎的側面から見た弱値の意味についても議論する。

Koji Tsumura

RG improvements on the CEDM via CP violating four-Fermi operators

Meeting room 1, Kenkyu honkan 1F
The electric dipole moment (EDM) is known to be a good probe of CP violation. In this talk, we focus the CP violating four-Fermi operators, which can mix with the EDM and chromo-EDM (CEDM) operators at one loop level. We show the renormalization-group equations (RGEs) for the (flavor-conserving) CP-violating interaction are derived up to the dimension six. We apply them to the models with the neutral scalar boson or the color-octet scalar boson which have CP-violating Yukawa interactions with quarks. Using the RGEs, the evaluation of the Barr-Zee diagram and the dimension five Weinberg operator is improved.

Kyohei Mukaida, Tokyo U

Boltzmann equation for non-equilibrium particles and its application to non-thermal dark matter production

Meeting room 1, Kenkyu honkan 1F
We consider a scalar field which is very weakly interacting with the thermal bath, and study thermal effects on the evolution of its number density. We use the Boltzmann equation derived from the Kadanoff-Baym equation, assuming that the degrees of freedom in the thermal bath are well described as “quasi-particles” with thermally modified dispersion relations. The obtained Boltzmann equation differs from the conventional one since the collision term is thermally modified through “quasi-particles.” Then, we apply this equation to the Freeze-In dark matter production scenario. We show that thermal effects can change the resultant dark matter abundance by ${cal O} (10-100) %$ compared to the result without taking account of thermal effects.

Corneliu Sochichiu, Sung KyunKwan U

Dirac Lattice or Down to High Energy

Meeting room 1, Kenkyu honkan 1F
I consider the conditions for the emergence of Dirac/Weyl/Majorana fermions from a (nonrelativistic) Fermi system.

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