\documentclass[12pt]{article} \usepackage[left=2.0cm,right=2.0cm,top=2.0cm,bottom=2.0cm]{geometry} \usepackage[dvips]{color} \renewcommand{\baselinestretch}{1.0} %%% FONT SIZE TABLE % Default : 12pt % Huge : 25pt % huge : 25pt % LARGE : 21pt % Large : 17pt % large : 14pt % normalsize : 12pt % small : 11pt % footnotesize: 10pt % scriptsize : 8pt % tiny : 6pt \begin{document} \pagestyle{empty} \parindent=0mm \parskip=0mm % Custom macros \newcommand{\lagr}{\cal{L}} \newcommand{\mueg}{$\mu^{+} \rightarrow e^{+}\gamma$~} \newcommand{\meee}{$\mu \rightarrow eee$~} \newcommand{\muenn}{$\mu \rightarrow e \nu \overline{\nu}$~} \newcommand{\muenng}{$\mu \rightarrow e \nu \overline{\nu} \gamma$~} \newcommand{\muec}{$\mu^{-} N \rightarrow e^{-} N$~} \newcommand{\muecaz}{$\mu^{-} + N(A,Z) \rightarrow e^{-} + N(A,Z)$~} \begin{center} %%% %%% TITLE %%% %{\large\bfseries The COMET Experiment and its Background Study} {\large\bfseries Status of the COMET Experiment at J-PARC} ~\\ %%% %%% AUTHOR(S) %%% \underline{Nam Hoai Tran}, on behalf of the COMET Collaboration ~\\ %%% %%% AFFILIATION %%% {\small\itshape Department of Physics, Graduate School of Science, \\ Osaka University, Osaka 560-0043, Japan}\\ ~\\ ~\\ %%% %%% EMAIL %%% {\small nam@kuno-g.phys.sci.osaka-u.ac.jp} %%% %%% %%% \end{center} %%% %%% BODY OF ABSTRACT %%% COMET [1] is an experiment that aims to search for a charged lepton flavor violation (CLFV) process, the muon-to-electron conversion in the presence of a nucleus, \muec. The process is forbidden in the Standard Model (SM), however is predicted to occur in various extensions of SM, such as . Current experimental upper limit of the branching ratio is $BR(\mu^{-} + Au \rightarrow e^{-} + Au) < 7 \times 10^{-13}$, set by the SINDRUM II experiment [2]. Using the J-PARC proton beam and the pion capture by a solenoidal field, COMET will have a single event sensitivity 10,000 times better than the current limit. The COMET collaboration has taken a phased approach in which the first phase, COMET Phase-I [3], starts in 2013 and initial data taking in around 2017. This paper provides some highlights among ongoing R\&D activities. %Charged lepton flavor violation (CLFV) has attracted much attention from %experimentalists and theorists in particle physics. The CLFV rates are %predicted to be in the order of of $O(10^{-54})$ in the Standard Model (SM). %Therefore, any experimental observations of CLFV would be an unambiguous signal %of new physics beyond the SM. COMET [1] is an experiment %that aims to search for a CLFV process of muon-to-electron conversion in the %presence of a nucleus, \muec. %Using the J-PARC proton beam and the pion capture by %a solenoidal field, COMET expects to have a sensitivity a factor of 10,000 %times that of the current limit. The COMET experiment has taken a phased %approach [2] in which the COMET Phase-I (first phase) will start its %construction in 2013 and initial data taking in around 2016. %The COMET Phase-I will be subjected to significant backgrounds from the %products of the nuclear muon capture process. However, experimental data on %this matter is insufficient. As so, precise measurements of the products, %including protons, neutrons and photons, are required for the design and %optimization of the experiment. Detailed of these measurements will be %presented. %%% %%% LIST OF REFERENCES %%% ~\\ ~\\ ~[1] D.~Bryman (The COMET collaboration): ``An experimental search for lepton flavor violating $\mu^- - e^-$ conversion at sensitivity of $10^{-16}$ with a slow-extracted bunched proton beam'', J-PARC Proposal, 2007. \\ ~[2] W.~Bertl (SINDRUM-II collaboration): Eur. Phys. J. C \textbf{47} (2006) 337-346.\\ ~[3] R. Akhmetshin (The COMET collaboration): ``Experimental proposal for Phase--I of the COMET experiment at J-PARC'', KEK/J-PARC-PAC 2012-10. %%% %%% END OF ABSTRACT %%% \end{document}