齋川賢一 , 東京大学宇宙線研究所
Axion production from topological defects
Meeting Room 1, Kenkyu Honkan 1F
The axion arises as a consequence of the spontaneous breaking of Peccei-Quinn (PQ) symmetry, which is a viable solution to the strong CP problem of quantum chromodynamics and may explain the dark matter of the universe. However, this PQ mechanism predicts the formation of topological defects such as strings and domain walls in the early universe, and the evolution and decay of these defects give some implications for the early universe cosmology. In particular, the analysis of the spectrum of axions radiated from networks of topological defects revealed that axions produced by the defects give significant contributions to the relic cold dark matter abundance. In this talk, I will report recent results of field-theoretic lattice simulations of topological defects and discuss cosmological constraints on axion models.
藤川和男, RIKEN Nishina Center
Universally valid Heisenberg uncertainty relation
Seminar room, Kenkyu honkan 3F The original formulation of the uncertainty relation by Heisenberg, which is based on a thought experiment with an emphasis on measurement processes, lacked a simple mathematical basis compared to the widely accepted relations of Kennard and Robertson. In fact, a commonly assumed form of the Heisenberg-type error-disturbance relation has been recently invalidated by spin-measurements at Vienna [J. Erhart, et al., Nature Phys. 8, 185 (2012)]. On the other hand, the analysis of measurement processes is missing in the relations of Kennard and Robertson. Here we suggest to reformulate the Heisenberg uncertainty relation in such a manner that it incorporates both the intrinsic quantum fluctuations and the effects of measurement, and yet with the same mathematical rigor as the relations of Kennard and Robertson and thus universally valid. This relation, which assumes the form δxδp ∼ ℏ(instead of ℏ/2) when written in a popular notation, is regarded as a combination of the past works on the uncertainty relation by Arthurs and Kelly, who emphasized the role of measurement apparatus, and by Ozawa who clarified the mathematical structure.
The original formulation of the uncertainty relation by Heisenberg, which is based on a thought experiment with an emphasis on measurement processes, lacked a simple mathematical basis compared to the widely accepted relations of Kennard and Robertson. In fact, a commonly assumed form of the Heisenberg-type error-disturbance relation has been recently invalidated by spin-measurements at Vienna [J. Erhart, et al., Nature Phys. 8, 185 (2012)]. On the other hand, the analysis of measurement processes is missing in the relations of Kennard and Robertson. Here we suggest to reformulate the Heisenberg uncertainty relation in such a manner that it incorporates both the intrinsic quantum fluctuations and the effects of measurement, and yet with the same mathematical rigor as the relations of Kennard and Robertson and thus universally valid. This relation, which assumes the form δxδp ∼ ℏ(instead of ℏ/2) when written in a popular notation, is regarded as a combination of the past works on the uncertainty relation by Arthurs and Kelly, who emphasized the role of measurement apparatus, and by Ozawa who clarified the mathematical structure.
Ref. K. Fujikawa. Phys. Rev. A85, 062117 (2012).
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
