Richard Hill, University of Chicago

Universal behavior in the scattering of heavy, weakly interacting dark matter on nuclear targets

Meeting room 3, Kenkyu honkan 1F
Particles that are heavy compared to the electroweak scale (M >> m_W), and that are charged under electroweak SU(2) gauge interactions display universal properties such as a characteristic fine structure in the mass spectrum induced by electroweak symmetry breaking, and an approximately universal cross section for scattering on nuclear targets. The heavy particle effective theory framework is developed to compute these properties. As illustration, the spin independent cross section for low-velocity scattering on a nucleon is evaluated in the limit M >> m_W, including complete leading-order matching onto quark and gluon operators, renormalization analysis, and systematic treatment of perturbative and hadronic-input uncertainties.

Keiko I. Nagao, KEK

Dark Matter in Inert Triplet Models

Meeting room 1, Kenkyu honkan 1F
Since the standard model (SM) does not accommodate dark matter candidate, new physics models are expected. In the inert triplet model (ITM), we introduce one triplet scalar which does not couple to the SM fermions. In this talk I plan to talk about the signature of the DM candidates in the model.

Andrey Tayduganov

Determining the photon polarization of the $b¥to s¥gamma$ using the $B¥to K_1(1270)¥gamma¥to(K¥pi¥pi)¥gamma$ decay

Seminar hall, 4 go-kan
Recently the radiative $B$ decay to the strange axial-vector mesons, $B¥to K_1(1270) ¥gamma$, has been observed with rather large rate. This process is particularly interesting as the subsequent $K_1$ decay into its three body final state allows to determine the polarization of the gamma, which is mostly left- (right-)handed for $¥overline{B} (B)$ in the SM while various new physics models predict additional right- (left-)handed components. A new method is proposed to determine the polarization, exploiting the full Dalitz plot distribution, which seems to reduce strongly the statistical errors. In order to obtain a theoretical prediction for this polarization measurement, it is necessary to understand the hadronic $K_1 ¥to K ¥pi ¥pi$ decay channel and its uncertainties. The strong decays of the $K_1$ mesons, namely the partial wave amplitudes as well as their relative phases, are revisited in the framework of the $^3P_0$ quark-pair-creation model. Then, the result on the sensitivity of the $B¥to K_1(1270) ¥gamma$ process to the photon polarization is presented.

Tsuyoshi Houri, Osaka City University

Geometrization of Hamiltonian Dynamics and Hidden Symmetry of Space-times

Meeting room 1, Kenkyu honkan 1F
It is known that motion of free particles in curved space-times is deeply connecting with symmetry of space-times. In particular, it has been revealed that besides isometry “hidden symmetry” is important in black hole space-times since it was discovered first in Kerr space-time. Therefore it is interesting question to study how hidden symmetry works in higher-dimensional black hole space-times. In this talk, we will study hidden symmetry of five-dimensional black ring space-times together with a “Geomtrization” method. According to Maupertuis’ principle, Hamiltonian dynamics result in geodesic problems on the corresponding manifolds, which is called “Geometrization.” In the first half of this talk, beginning with a review of hidden symmetry, we will introduce the geometrization carefully. After that, hidden symmetry of five-dimensional black ring space-times will be discussed.

Kentaroh Yoshida, Kyoto University

Classical integrable structure of deformed sigma models

Meeting room 1, Kenkyu honkan 1F
We show that Yangian x quantum group symmetries are realized in two-dimensional sigma models whose target spaces are three-dimensional squashed spheres, warped AdS spaces and Schrodinger spacetimes. These symmetries enable us to develop two descriptions to describe its classical dynamics, according to the left and right symmetries. Each of the Lax pairs constructed in both ways leads to the same equations of motion. The two descriptions are related one another through a non-local map.

Kunihisa Morita, Waseda Institute for Advanced Study


Seminar room, Kenkyu honkan 3F

坂口貴男, Brookhaven National Laboratory


Seminar room, Kenkyu honkan 3F
2000年よりRHICで始まった重イオン衝突の実験においては、これまで生成量が小さかったために困難であった、ハード過程を利用した研究が可能となった。衝突でできた高温高密度物質と、ハード過程で散乱されたパートンの相互作用によって起きた、高横運動量ハドロンの収量の抑制は、この研究手法における大きな成果の一つであるが、その解釈を決定的にしたのが、衝突初期の情報をそのまま持ち出す単光子の測定である。 単光子は衝突初期から、系がハドロン化するまでに、連続的に放射されるため、重イオン衝突を系統的に研究する、最適のプローブである。 本講演では、重イオン衝突における単光子測定の歴史と、その測定手法、そしてRHICにおける最新の測定結果を紹介する。

Handhika Satrio Ramadhan, LIPI

Exotic Transitions in 6d Flux Compactifications

Room 345, 4 go-kan
“We present two profound tunneling phenomena in 6d Toy Model of Flux compactification. The first is a non-perturbative instability of the flux vacua, where the tunneling is achieved by dropping all the flux altogether and tunnel to no-flux state. We found that this state is a state with no (classical) space-time. It is a tunneling to Nothing, i.e., a bubble of nothing (reminiscent to the Wittens bubble of nothing). The second is the reverse-process, i.e., that the flux vacua can be spontaneously created from Nothing. We dubbed it Bubble from Nothing. Finally we show that a bubble from nothing is stable against nucleation of bubble of nothing, and in fact there is a smooth transition between the two.”

Mitsuru Kakizaki, Toyama University

Dark matter in UED : the role of the second KK level

Room 345, 4 go-kan
We perform a complete calculation of the relic abundance of the KK-photon LKP in the universal extra dimension model including all coannihilation channels and all resonances. We show that the production of level 2 particles which decay dominantly into SM particles contribute significantly to coannihilation processes involving level 1 KK-leptons. As a result the preferred dark matter scale is increased to R^{-1}=1.3 TeV. A dark matter candidate at or below the TeV scale can only be found in the non-minimal model by reducing the mass splittings between the KK-particles and the LKP. The LKP nucleon scattering cross section is typically small, ¥sigma <10^{-10} pb, unless the KK-quarks are nearly degenerate with the LKP.

Shuichiro Yokoyama, Nagoya University


Meeting room 1, Kenkyu honkan 1F

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