Multi bunch GMMA Ray generation experiment at ATF

We construct a new detector to monitor $\gamma$ yields in bunch by bunch basis for the Laser Compton experiment at the KEK ATF which is capable to separate $\gamma$ rays in 5.6ns-spacing multi-bunch operation of the KEK ATF. In this article we report a result of measurement of multi bunch $\gamma$ ray detection for the first time at the KEK ATF.Comment: 6 pagese 4 figures, Proceedings of POSIPOL 2011, Beijing Aug. 201

How Well Can We Reconstruct the ttbar System Near its Threshold at Future e+e- Linear Colliders?

We developed a new method for full kinematical reconstruction of the ttbar system near its threshold at future linear e+e- colliders. In the core of the method lies likelihood fitting which is designed to improve measurement accuracies of the kinematical variables that specify the final states resulting from ttbar decays. The improvement is demonstrated by applying this method to a Monte-Carlo ttbar sample generated with various experimental effects including beamstrahlung, finite acceptance and resolution of the detector system, etc. In most cases the fit brings a broad non-Gaussian distribution of a given kinematical variable to a nearly Gaussian shape, thereby justifying phenomenological analyses based on simple Gaussian smearing of parton-level momenta. The standard deviations of the resultant distributions of various kinematical variables are given in order to facilitate such phenomenological analyses. A possible application of the kinematical fitting method and its expected impact are also discussed.Comment: 14 pages, LaTeX, 11 figure

A study of the measurement precision of the Higgs boson decaying into tau pairs at the ILC

We evaluate the measurement precision of the production cross section times the branching ratio of the Higgs boson decaying into tau lepton pairs at the International Linear Collider (ILC). We analyze various final states associated with the main production mechanisms of the Higgs boson, the Higgs-strahlung and WW-fusion processes. The statistical precision of the production cross section times the branching ratio is estimated to be 2.6% and 6.9% for the Higgs-strahlung andWW-fusion processes, respectively, with the nominal integrated luminosities assumed in the ILC Technical Design Report; the precision improves to 1.0% and 3.4% with the running scenario including possible luminosity upgrades. The study provides a reference performance of the ILC for future phenomenological analyses.Comment: 10 pages, 6 figures, 9 tables, revised from v

Gene Expression and the Physiological Role of Transforming Growth Factor-α in the Mouse Pituitary

Transforming growth factor-alpha (TGF-alpha), a member of the epidermal growth factor (EGF) family, is produced within the mouse anterior pituitaries. However, the cell types of TGF-alpha-expressing cells and the physiological roles of TGF-a within mouse pituitary glands remain unclear. The aim of the present study was to localize TGF-alpha mRNA-expressing cells, and to clarify the involvement of TGF-alpha in estrogen-induced DNA replication in mouse anterior pituitary cells. Northern blot analysis demonstrated TGF-alpha mRNA expression in adult male and female mouse anterior pituitaries. In situ hybridization analysis of the pituitaries in these mice showed that TGF-alpha mRNA-expressing cells in the anterior pituitary are round, oval, and medium-sized. TGF-alpha mRNA was colocalized in most of the growth hormone (GH) mRNA-expressing cells, while only some of the prolactin (PRL) mRNA-expressing cells. DNA replication in the anterior pituitary cells was detected by monitoring the cellular uptake of a thymidine analogue, bromodeoxyuridine (BrdU) in a primary serum-free culture system. Estradiol-17beta (E2) and TGF-alpha treatment increased the number of BrdU-labelled mammotrophs, indicating that E2 and TGF-alpha treatment stimulates the DNA replication in mammotrophs. Immunoneutralization of TGF-alpha with anti-TGF-alpha-antibodies nullified the E2-induced increase in DNA replication. RT-PCR analysis of TGF-alpha mRNA expression in ovariectomized female mice revealed that E2 increases TGF-alpha mRNA levels. These results indicate that the TGF-alpha produced primarily in the somatotrophs mediates the stimulatory effects of estrogen on the DNA replication of pituitary cells in a paracrine or autocrine manner

A feasibility study of the measurement of Higgs pair creation at a Photon Linear Collider

We studied the feasibility of the measurement of Higgs pair creation at a Photon Linear Collider (PLC). From the sensitivity to the anomalous self-coupling of the Higgs boson, the optimum $\gamma \gamma$ collision energy was found to be around 270 GeV for a Higgs mass of 120 GeV/$c^2$. We found that large backgrounds such as $\gamma \gamma \rightarrow W^+W^-, ZZ,$ and $b\bar{b}b\bar{b}$, can be suppressed if correct assignment of tracks to parent partons is achieved and Higgs pair events can be observed with a statistical significance of $\sim 5 \sigma$ by operating the PLC for 5 years.Comment: 7 pages, 8 figures, 5 table

New Supporting Evidence for the Overdensity of Galaxies around the Radio-Loud Quasar SDSS J0836+0054 at z =5.8

Recently, Zheng et al. (2005) found evidence for an overdensity of galaxies around a radio-loud quasar, SDSS J0836+0054, at z=5.8 (a five arcmin$^2$ region). We have examined our deep optical imaging data (B, V, r', i', z', and NB816) taken with the Suprime-Cam on the Subaru Telescope. The NB816 narrow-band filter (lambda_c = 815 nm and $\Delta\lambda = 12$ nm) is suitable for searching for Ly$\alpha$ emitters at $z\approx 5.7$. We have found a new strong Ly$\alpha$ emitter at $z \approx 5.7$ close to object B identified by Zheng et al. Further, the non detection of the nine objects selected by Zheng et al. (2005) in our B, V, and r' images provides supporting evidence that they are high-z objects.Comment: 5 pages, 1 figure, accepted for PAS