What's new


日時:2015年02月04日 (水) 14:00-

講師:Paul Jackson (University of Adelaide)
題目:「Third generation SUSY at the LHC and Kinematic Variables for new physics searches」

Signal events where multiple missing neutral particles are present in a final state represent challenging topologies to search for new physics at the LHC. The key to any search is the ability to separate background-like events from signal-like events. Identifying such signal-like events, and extracting their properties, is exacerbated by a lack of knowledge of the particle masses and some missing kinematic handles. In this talk we will briefly summarise the state-of-the-art of searches for third generation Supersymmetry with the ATLAS experiment. Then, we present a new method to search for open final states where the decays of the two parent particles may proceed via the same, or different, channels. For final states with weakly interacting particles, a new basis of variables can be derived using the "Recursive Jigsaw" technique. We discuss the application of this procedure by considering final states containing 2 b-jets, 2 charged leptons and missing transverse momentum. We apply the “Recursive Jigsaw” reconstruction to extract quantities sensitive to scales and angles on an event-by-event basis. The utility of this variable basis is demonstrated by studying dileptonic ttbar decays in comparison to various parameter choices for direct third generation scalar top quark (stop) production, where each stop decays to bottom chargino, which subsequently decay to a neutralino LSP via either on- or off-shell W decay. The applicability of the variable basis is further demonstrated using resonant ttbar production through a heavy graviton.


日時:2014年10月31日 (火) 11:30-
会場:ES館 ES706

題目:New method for precise determination of top quark mass at LHC

The mass of the top quark is an important input parameter to the Standard Model and models of new physics. Recently a measurement of the top quark mass with an accuracy of 0.8GeV has been reported. This mass, however, is not identical to the pole mass nor well-defined in perturbative QCD. On the other hand, the present error of the (theoretically more preferable) top quark MSbar mass is still large with 4-5GeV. In this study, we propose a new method to measure a theoretically well-defined top quark mass at the LHC. This method requires only lepton energy distribution and is basically independent of the production process of the top quark. We perform a simulation analysis of the top quark mass measurement with ttbar pair production and lepton+jets decay channel at the leading order. The estimated statistical error of the top quark mass is about 0.4GeV with an integrated luminosity of 100fb^{-1} at \sqrt{s}=14TeV. We also estimate some of the major systematic uncertainties and find that they are under good control. By including higher-order corrections, the MSbar mass of the top quark can be determined.


現在、着々と準備が進んでいる国際リニアコライダー計画についての講演会素粒子宇宙起源研究機構、理学研究科タウ・レプトン物理研究センター共催で開催致します。講演会は、物理、加速器、全体計画の3部構成となっており、特に全体計画はリニアコライダー国際推進委員会 (Linear Collider Board:LCB)委員長である駒宮先生にお話していただきます。非専門家や、学部生にも分かりやすい講演をお願いしてありますでの、皆様奮ってご参加ください。

会場:理学南館 坂田平田ホール


日時:2014年1月21日 (火) 15:00-
会場:ES館 ES635

題目:「Study of proton spin structure at RHIC-spin」

It is well known that the spin of proton is 1/2, but its origin is poorly known. Past measurements on quark helicity distribution show that quark spin carries only 20-30% of the proton spin. This is a long-standing problem called "proton spin puzzle". In order to solve the problem, we are measuring gluon spin contribution at Relativistic Heavy Ion Collider using polarized proton beams (RHIC-spin).
I will show recent results of RHIC-spin and discuss how the results improve our understanding of proton spin. I will also mention future upgrades of RHIC-spin.


日時:2013年10月11日 (金) 15:00-
会場:ES館 ES635


T2K(Tokai-To-Kamioka)実験は世界初のoff-axisニュートリノビームを用いた長基線ニュートリノ振動実験である。2010年の実験開始より現在までに6.3x10^20 Proton on Target (POT)のデータを取得した。 今回、このデータを用いて行ったミューオンニュートリノから電子型ニュートリノへの振動現象(nu_e appearance現象)の解析結果を報告する。またミューオンニュートリノの消失を研究した成果も報告する予定である。


日時:2013年6月14日 (金) 15:00-
会場:ES館 ES635

講師:Yannis Semertzidis (BNL)
題目:Storage Ring EDM method: probing the proton and the deuteron with highest EDM sensitivity

The Storage Ring EDM method was developed based on the muon g-2 experimental techniques. The muon g-2 experiment provides, indirectly, some sensitivity to muon EDM. We have focused on developing a dedicated Storage Ring EDM method, first for the muon (10^{-24} e.cm) and then the proton (10^{-29} e.cm with 10^{-30} e.cm a distinct possibility) and deuteron (10^{-29} e.cm) nuclei, to optimize sensitivity on the particle EDM. For the proton and deuteron beams, the available polarized beam intensities provide a revolution in statistical sensitivity and a great opportunity to answer the matter-antimatter asymmetry mystery of our universe.


名古屋大学 タウ・レプトン物理研究センター

Nagoya University Tau-Lepton Physics Research Center

〒464-8602 名古屋市千種区不老町 名古屋大学大学院理学研究科

Phone:052-789-2902 Fax:052-782-5752