%================================================================ % LaTeX file with prefered layout for H1 paper drafts % use: dvips -D600 file-name %================================================================ \documentclass[12pt]{article} \usepackage{epsfig} \usepackage{graphicx} \usepackage{amsmath} \usepackage{hhline} \usepackage{amssymb} \usepackage{times} \usepackage{cite} \renewcommand{\topfraction}{1.0} \renewcommand{\bottomfraction}{1.0} \renewcommand{\textfraction}{0.0} \newlength{\dinwidth} \newlength{\dinmargin} \setlength{\dinwidth}{21.0cm} \textheight23.5cm \textwidth16.0cm \setlength{\dinmargin}{\dinwidth} \setlength{\unitlength}{1mm} \addtolength{\dinmargin}{-\textwidth} \setlength{\dinmargin}{0.5\dinmargin} \oddsidemargin -1.0in \addtolength{\oddsidemargin}{\dinmargin} \setlength{\evensidemargin}{\oddsidemargin} \setlength{\marginparwidth}{0.9\dinmargin} \marginparsep 8pt \marginparpush 5pt \topmargin -42pt \headheight 12pt \headsep 30pt \footskip 24pt \parskip 3mm plus 2mm minus 2mm %===============================title page============================= \begin{document} % The rest \newcommand{\pom}{{I\!\!P}} \newcommand{\reg}{{I\!\!R}} \newcommand{\slowpi}{\pi_{\mathit{slow}}} %\newcommand{\gevsq}{\mathrm{GeV}^2} \newcommand{\fiidiii}{F_2^{D(3)}} \newcommand{\fiidiiiarg}{\fiidiii\,(\beta,\,Q^2,\,x)} \newcommand{\n}{1.19\pm 0.06 (stat.) \pm0.07 (syst.)} \newcommand{\nz}{1.30\pm 0.08 (stat.)^{+0.08}_{-0.14} (syst.)} \newcommand{\fiidiiiful}{F_2^{D(4)}\,(\beta,\,Q^2,\,x,\,t)} \newcommand{\fiipom}{\tilde F_2^D} \newcommand{\ALPHA}{1.10\pm0.03 (stat.) \pm0.04 (syst.)} \newcommand{\ALPHAZ}{1.15\pm0.04 (stat.)^{+0.04}_{-0.07} (syst.)} \newcommand{\fiipomarg}{\fiipom\,(\beta,\,Q^2)} \newcommand{\pomflux}{f_{\pom / p}} \newcommand{\nxpom}{1.19\pm 0.06 (stat.) \pm0.07 (syst.)} \newcommand {\gapprox} {\raisebox{-0.7ex}{$\stackrel {\textstyle>}{\sim}$}} \newcommand {\lapprox} {\raisebox{-0.7ex}{$\stackrel {\textstyle<}{\sim}$}} \def\gsim{\,\lower.25ex\hbox{$\scriptstyle\sim$}\kern-1.30ex% \raise 0.55ex\hbox{$\scriptstyle >$}\,} \def\lsim{\,\lower.25ex\hbox{$\scriptstyle\sim$}\kern-1.30ex% \raise 0.55ex\hbox{$\scriptstyle <$}\,} \newcommand{\pomfluxarg}{f_{\pom / p}\,(x_\pom)} \newcommand{\dsf}{\mbox{$F_2^{D(3)}$}} \newcommand{\dsfva}{\mbox{$F_2^{D(3)}(\beta,Q^2,x_{I\!\!P})$}} \newcommand{\dsfvb}{\mbox{$F_2^{D(3)}(\beta,Q^2,x)$}} \newcommand{\dsfpom}{$F_2^{I\!\!P}$} \newcommand{\gap}{\stackrel{>}{\sim}} \newcommand{\lap}{\stackrel{<}{\sim}} \newcommand{\fem}{$F_2^{em}$} \newcommand{\tsnmp}{$\tilde{\sigma}_{NC}(e^{\mp})$} \newcommand{\tsnm}{$\tilde{\sigma}_{NC}(e^-)$} \newcommand{\tsnp}{$\tilde{\sigma}_{NC}(e^+)$} \newcommand{\st}{$\star$} \newcommand{\sst}{$\star \star$} \newcommand{\ssst}{$\star \star \star$} \newcommand{\sssst}{$\star \star \star \star$} \newcommand{\tw}{\theta_W} \newcommand{\sw}{\sin{\theta_W}} \newcommand{\cw}{\cos{\theta_W}} \newcommand{\sww}{\sin^2{\theta_W}} \newcommand{\cww}{\cos^2{\theta_W}} \newcommand{\trm}{m_{\perp}} \newcommand{\trp}{p_{\perp}} \newcommand{\trmm}{m_{\perp}^2} \newcommand{\trpp}{p_{\perp}^2} \newcommand{\alp}{\alpha_s} \newcommand{\alps}{\alpha_s} \newcommand{\sqrts}{$\sqrt{s}$} \newcommand{\LO}{$O(\alpha_s^0)$} \newcommand{\Oa}{$O(\alpha_s)$} \newcommand{\Oaa}{$O(\alpha_s^2)$} \newcommand{\PT}{p_{\perp}} \newcommand{\JPSI}{J/\psi} \newcommand{\sh}{\hat{s}} %\newcommand{\th}{\hat{t}} \newcommand{\uh}{\hat{u}} \newcommand{\MP}{m_{J/\psi}} %\newcommand{\PO}{\mbox{l}\!\mbox{P}} \newcommand{\PO}{I\!\!P} \newcommand{\xbj}{x} \newcommand{\xpom}{x_{\PO}} \newcommand{\ttbs}{\char'134} \newcommand{\xpomlo}{3\times10^{-4}} \newcommand{\xpomup}{0.05} \newcommand{\dgr}{^\circ} \newcommand{\pbarnt}{\,\mbox{{\rm pb$^{-1}$}}} \newcommand{\gev}{\,\mbox{GeV}} \newcommand{\WBoson}{\mbox{$W$}} \newcommand{\fbarn}{\,\mbox{{\rm fb}}} \newcommand{\fbarnt}{\,\mbox{{\rm fb$^{-1}$}}} % % Some useful tex commands % \newcommand{\qsq}{\ensuremath{Q^2} } \newcommand{\gevsq}{\ensuremath{\mathrm{GeV}^2} } \newcommand{\et}{\ensuremath{E_t^*} } \newcommand{\rap}{\ensuremath{\eta^*} } \newcommand{\gp}{\ensuremath{\gamma^*}p } \newcommand{\dsiget}{\ensuremath{{\rm d}\sigma_{ep}/{\rm d}E_t^*} } \newcommand{\dsigrap}{\ensuremath{{\rm d}\sigma_{ep}/{\rm d}\eta^*} } % Journal macro \def\Journal#1#2#3#4{{#1} {\bf #2} (#3) #4} \def\NCA{\em Nuovo Cimento} \def\NIM{\em Nucl. Instrum. Methods} \def\NIMA{{\em Nucl. Instrum. Methods} {\bf A}} \def\NPB{{\em Nucl. Phys.} {\bf B}} \def\PLB{{\em Phys. Lett.} {\bf B}} \def\PRL{\em Phys. Rev. Lett.} \def\PRD{{\em Phys. Rev.} {\bf D}} \def\ZPC{{\em Z. Phys.} {\bf C}} \def\EJC{{\em Eur. Phys. J.} {\bf C}} \def\CPC{\em Comp. Phys. Commun.} \begin{titlepage} \begin{center} %{\it {\large version 1.08 of \today}} \\[.3em] \begin{small} \begin{tabular}{llrr} %Submitted to & \multicolumn{3}{r}{\footnotesize Electronic Access: {\it http://www-h1.desy.de/h1/www/publications/conf/conf\_list.html}} \\[.2em] \hline %Submitted to & \multicolumn{3}{r}{\footnotesize {\it www-h1.desy.de/h1/www/publications/conf/conf\_list.html}} \\[.2em] \hline Submitted to & & & %\epsfig{file=/h1/www/images/H1logo_bw_small.epsi,width=2.cm} \\[.2em] \hline \epsfig{file=H1logo_bw_small.epsi,width=2.cm} \\[.2em] \hline \multicolumn{4}{l}{{\bf XV International Workshop on Deep-Inelastic Scattering and Related Subjects,}}\\ \multicolumn{4}{l}{{ DIS 2007 April~16-20,~2007,~Munich}} \\ % & Abstract: & &\\ % & Parallel Session: & &\\ \hline & \multicolumn{3}{r}{\footnotesize {\it www-h1.desy.de/h1/www/publications/conf/conf\_list.html}} \\[.2em] \end{tabular} \end{small} \end{center} % \noindent % Date: \\ % Version: \\ % Editors: \\ % Referees: \\ % Comments by %\begin{flushright} %H1prelim-04-063\\ %July 28, 2004 %\end{flushright} \vspace{2cm} \begin{center} \begin{Large} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% {\bf \boldmath Multi--lepton events at HERA} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \vspace{2cm} H1 Collaboration \end{Large} \end{center} \vspace{1cm} \begin{abstract} \noindent A search for multi--lepton (electron or muon) events at high transverse momenta is performed on a data sample collected in $e^\pm p$ collisions with the H1 detector at HERA during the period 1994--2007. This data sample corresponds to an integrated luminosity of 459 pb$^{-1}$. With respect to the published HERA I multi-electron and multi-muon analyses, additional topologies with high $P_T$ electrons and muons are investigated. Yields of di-lepton and tri-lepton events are measured and a general good agreement is found with the Standard Model (SM) predictions. Combining all channels, four events are observed with a scalar sum of lepton transverse momenta ($\sum P_T $) greater than 100 GeV, compared to a SM expectation of 1.9 $\pm$ 0.4. The four events with $\sum P_T >$ 100 GeV are observed in $e^{+}p$ collisions only where the SM expectation is of 1.2 $\pm$ 0.2. \end{abstract} \vspace{1.5cm} \end{titlepage} \newpage \pagestyle{plain} %\clearpage % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % \section{Multi-lepton Analysis} % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % % % Multi--lepton (electron or muon) production is measured at high % transverse momentum using the full HERA data sample. In addition to an % update of the published HERA I multi-electron and multi-muon analyses, new topologies with high $P_T$ electrons and muons are investigated here for the % first time. Yields of di-lepton and tri-lepton events are measured and % a general good agreement is found with the Standard Model predictions. % However, combining all channels, four events are observed with a scalar sum of lepton transverse momenta greater than 100 GeV, compared to a Standard Model expectation % of 1.1 $\pm$ 0.22. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \section{Introduction} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Within the Standard Model (SM) the production of multi-lepton events in $ep$ collisions mainly proceeds via photon-photon interactions\cite{Vermaseren:1982cz}. Precise cross-section measurements of both electron (e) and muon ($\mu$) pair production at high transverse momentum ($P_T$) have already been performed by the H1 collaboration \cite{Aktas:2003jg,Aktas:2003sz} using HERA~I data taken until 2000. At large di-electron masses, an excess of events is observed in both the di-electron and tri-electron samples \cite{Aktas:2003jg}. The present analysis extends our previous measurements to the e$\mu$ and e$\mu\mu$ topologies and to a higher luminosity, combining all HERA~II data taken in 2003--2007 (${\cal L} =$ 341 pb$^{-1}$) with the previous HERA~I data sample from 1994--2000 (${\cal L} =$ 118 pb$^{-1}$). %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \section{Standard Model Processes and their Simulation} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Multi--lepton events are generated with the GRAPE ~\cite{Abe:2000cv} program, which includes all electroweak matrix elements at tree level. Multi-lepton production via $\gamma \gamma$, $\gamma Z$, $ZZ$ collisions, internal photon conversion and the decay of virtual or real $Z$ bosons is considered. Initial and final state QED radiation is included. The complete hadronic final state is simulated via interfaces to PYTHIA and SOPHIA~\cite{Mucke:1999yb} for the inelastic and quasi-elastic regimes, respectively. Consequently, GRAPE predicts $ep \rightarrow \mu \mu X$ and $ep \rightarrow e e X$, as well as $ep \rightarrow e \mu \mu X$ and $ep \rightarrow e e e X$ if the scattered electron is detected. %Processes with an additional radiated photon are %also modelled. The $ep \rightarrow \tau \tau X$ process is also simulated with GRAPE and its contribution was found to be negligible. The dominant background contributions arise from neutral current deep-inelastic scattering (DIS) events ($ep \rightarrow e X$) \cite{Aktas:2003jg}. QED Compton scattering $ep \rightarrow e \gamma X$ can also contribute. The DIS and elastic Compton processes are simulated using the RAPGAP~\cite{Jung:1993gf} (for HERA I) or DJANGO~\cite{Schuler:yg} (HERA II) and WABGEN~\cite{Berger:kp} generators, respectively. All generated events are passed through the full GEANT \cite{Brun:1987ma} based simulation of the H1 apparatus, which takes into account the running conditions of the different data taking periods. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \section{Multi-lepton Event Selection} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% The electron identification procedure follows the criteria described in \cite{Aktas:2003jg}. Electron candidates with energies above 5 GeV are identified in the liquid argon and backward calorimeters, in the range $5^\circ < \theta < 175^\circ$. Electron candidates are required to be isolated by demanding that they are separated from other leptons or jets by at least 0.5 units in the pseudorapidity-azimuth ($\eta-\phi$) plane. In addition, the total hadronic energy within 0.75 units in $\eta-\phi$ of the electron direction is required to be below 2.5 \% of the electron energy. In the region of angular overlap between the liquid argon calorimeter and the central drift chambers ($20^\circ < \theta < 150^\circ$), the calorimetric electron identification is complemented by tracking conditions. In this region it is required that a high quality track geometrically matches the electromagnetic cluster within a distance of closest approach to the cluster centre-of-gravity of $12$~cm. No other good track is allowed within $0.5$ units in $\eta-\phi$ around the electron direction. In the central region ($20^\circ < \theta < 150^\circ$) the distance between the first measured point in the central drift chambers and the beam axis is required to be below $30$~cm in order to reject photons that convert late in the central tracker material. In addition, in this central region, the transverse momentum measured from the associated track $P_T^{e_{tk}}$ is required to match the calorimetric measurement $P_T^e$ with $1/P_T^{e_{tk}} - 1/P_T^e < 0.02$~GeV$^{-1}$. This criteria is relaxed to 0.04 for the new HERA II data %to match the changes of calibrations. since a final calibration and alignment have not been performed yet. Due to the higher material density in the forward region ($5^\circ < \theta < 20^\circ$) the electrons are more likely to shower and therefore no track conditions are required. The same applies in the backward region ($150^\circ < \theta < 175^\circ$). The electron energy threshold is raised to 10~GeV in the forward region. Muon candidates are identified with a $P_T$ $>$ 2 GeV in the range $20^\circ < \theta < 160^\circ$, with a similar procedure to that described in \cite{Aktas:2003sz}. The muon identification is based on a track in the inner tracking systems associated with a track segment or an energy deposit in the instrumented iron~\cite{Andreev:2003pm}. %The muon identification is based on a track in the forward muon system or the inner tracking systems associated with a track segment or an energy deposit in the instrumented iron~\cite{Andreev:2003pm}. %The momentum of the muons detected in the forward muon detector is measured from the curvature in a toroidal magnetic field. The muon momentum is measured in the central region from the track curvature in the solenoidal magnetic field. A muon candidate should have no more than 5~GeV deposited in the LAr calorimeter in a cylinder of radius 25 cm and 50 cm in the electromagnetic and hadronic sections of the LAr calorimeter, respectively, centred on the muon track direction. In di-muon events, the requirement of an opening angle between the two muons smaller than $160^\circ$ discards cosmic rays background. Beam halo events are rejected by requiring that the muons originate from the event vertex. Finally, misidentified hadrons are strongly suppressed by requiring that the muon candidate be separated from the closest jet and from any good quality track by 1 unit in the $\eta-\phi$ plane. % Muon canditates are also required to be isolated from other leptons by at least 0.5 units in the $\eta-\phi$ plane. The final multi-lepton selection requires that there be at least two central ($20^\circ < \theta < 150^\circ$) lepton (electron or muon) candidates, of which one must have $P_T^l > 10$ GeV and the other $P_T^{l} > 5$ GeV. Additional lepton candidates are identified in the detector according to the above criteria without any additional explicit $P_T$ or angular requirement. The lepton candidates are ordered according to decreasing $P_T$, $P_T^{l_i} > P_T^{l_{i+1}}$. The selected events are classified as belonging to the two lepton sample if only two central leptons are identified, and to the three lepton sample if exactly one additional lepton candidate is identified. According to the flavours of the identified leptons, these samples are further classified into ee, $\mu\mu$, e$\mu$, eee and e$\mu\mu$. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%\subsection{Systematic Uncertainties} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%% %%% %%%The electromagnetic energy scale uncertainty varies between 0.7 \% and %%%3 \% depending on the particle's impact on the LAr calorimeter %%%surface~\cite{Adloff:2003uh} for HERA I data. For new HERA II data %%%this uncertainty is determined to be 1.5 \% and 3 \% in the central %%%($z\,<\,100$~cm) and forward regions ($z\,>\,100$~cm), respectively. %%%The angular uncertainty of electromagnetic clusters are 3 and 5 mrad %%%in HERA I and HERA II data, respectively. The identification of %%%central electrons depends on the tracking efficiency which is known %%%with a precision ranging from 3 \% for polar angles around 90$^\circ$ %%%to 15 \% at the forward edge of the angular acceptance of the central %%%tracker ($\theta =$ 20 $^\circ$) \cite{Aktas:2003jg}. The uncertainty %%%on the transverse momentum measurement for muons is 5~\%. The %%%uncertainty on the muon polar angle is $3$~mrad. The muon %%%identification efficiency is known with a precision of 5\%. The %%%hadronic energy scale of the LAr calorimeter is known to 2 \%. The %%%uncertainty on the trigger efficiency is estimated to be 5 \%. It is %%%10 \% for di-muon only events in HERA II data. The uncertainty in the %%%integrated luminosity results in an overall normalisation error of %%%1.5~\% for HERA I data and 3 \% for HERA II data. The theoretical %%%uncertainty on the pair production process cross section, calculated %%%with GRAPE, is 3~\% \cite{Aktas:2003jg}. The uncertainty on the %%%Compton and DIS background contributions is 20~\%. %%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \section{Results} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% The event yields observed in all channels are summarised in table \ref{tab:mlepyields}. The observed event yields are in good agreement with SM expectations, which are dominated by pair production. %One %e$\mu$ data event with an additional radiated low $P_T$ photon enters %in the ee$\mu$ class for 0.92 $\pm$ 0.56 expected. % In addition to the events in the classes listed, one event is classified as $ee\mu$. Upon closer inspection, this event is consistent with an $e\mu$ topology with an additional radiated low $P_T$ photon. 0.92 $\pm$ 0.56 such events are expected. % One event is % identified as a four lepton event, compared to a SM expectation of % 0.56 $\pm$ 0.14, which is domintated by three lepton events containing % a radiated photon. The data event is consistent with this explanation. Such % events enter the sample because no tracks are required to be % associated with the electron cluster at the most backward angles ($\theta % >$ 150$^\circ$). No event with three muons is observed. The distributions of the invariant mass of the two leptons in the di-lepton event classes are presented in figure \ref{fig:M2lep}. The agreement with the SM prediction is good. In the ee invariant mass distribution, for $M_{12}$~$>$~100~GeV, three events previously described in \cite{Aktas:2003jg} are present, compared to an expectation of 1.5 $\pm$ 0.3 (see table \ref{tab:mlepyieldsM100}). The distribution of the invariant mass $M_{12}$ of the two highest $P_T$ electrons for the eee sample is shown in figure \ref{figM3lep}, as well as the invariant mass combinations of the electron with the higest $P_T$ muon ($M_{e\mu}$) and of both muons ($M_{\mu\mu}$) in the e$\mu\mu$ sample. The event yields in the tails of invariant mass distributions ($M >$ 100 GeV) of all channels are summarised in table \ref{tab:mlepyieldsM100}. The three ee events with $M_{12} >$ 100 GeV are observed in HERA~I data and are discussed in \cite{Aktas:2003jg}, as well as the three eee with $M_{12} >$ 100 GeV. Two e$\mu\mu$ events are observed in the new HERA~II data, of which one has a high muon-muon and the other a high electron-muon invariant mass. The e$\mu\mu$ event with the high $M_{e\mu}$ invariant mass is shown in figure \ref{fig:emumu_evtdisp}. The distributions of the scalar sum of $P_T$ of all identified leptons for the combination of di-- and tri--lepton samples is shown in figure \ref{fig:SumEt_All_lep}. For $\sum P_T >$ 100 GeV 4 events are observed in all channels combined while 1.9 $\pm$ 0.4 are expected. These four data events correspond to the three ee events observed in HERA I data \cite{Aktas:2003jg} and one new e$\mu\mu$ event observed in HERA~II data. The separation of the total HERA data sample between events taken in collisions with a positron or electron beam is also presented in figure \ref{fig:SumEt_All_lep} and in table \ref{tab:mlepyieldsM100}. All high invariant masses and $\sum P_T$ events have been recorded in $e^+p$ collisions and none is observed in $e^-p$ data. In $e^+p$ collisions and for $\sum P_T >$ 100 GeV 4 events are observed in all channels combined while 1.2 $\pm$ 0.1 are expected (see table \ref{tab:mlepyieldsEt100}). % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % \subsection{Results for 2005 data} % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % % The multi-lepton analysis has been carried out on recent $e^{-}p$ data. % The event yields observed in all channels for this data sample are summarised in table \ref{tab:mlepyields_2005}. A good agreement with the SM expectation is observed. % The distribution of the invariant mass of the two higest $P_T$ electrons for events classified as ee and eee is presented in figure \ref{fig:DIS2005}. The distribution of the scalar sum of $P_T$ of all identified leptons for the combination of di and tri--lepton samples is also shown. No new events with high $P_T$ leptons or at high invariant mass are observed. % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \section{Summary} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% The production of multi-leptons (electrons and muons) at high transverse momenta in $ep$ scattering has been studied. The measurement extends previous analyses \cite{Aktas:2003jg,Aktas:2003sz} by including the HERA~II data. The integrated luminosities corresponding to $e^+p$ and $e^-p$ collisions are 286 pb$^{-1}$ and 173 pb$^{-1}$, respectively. The event yields in the di-lepton (ee, $\mu\mu$ and e$\mu$) and tri-lepton (eee and e$\mu\mu$) sub-samples are in good agreement with the SM predictions. The distribution of the scalar sum of transverse momenta of the leptons is studied for the combination of all di- and tri-lepton sub-samples. For $\sum P_T >$ 100 GeV 4 events are observed while 1.9 $\pm$ 0.4 are expected. \newpage %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \begin{thebibliography}{99} %\cite{Vermaseren:1982cz} \bibitem{Vermaseren:1982cz} J.~A.~M.~Vermaseren, %``Two Photon Processes At Very High-Energies,'' Nucl.\ Phys.\ B {\bf 229} (1983) 347. %%CITATION = NUPHA,B229,347;%% %\cite{Aktas:2003jg} \bibitem{Aktas:2003jg} A.~Aktas {\it et al.} [H1 Collaboration], %``Multi-electron production at high transverse momenta in e p collisions at HERA,'' Eur.\ Phys.\ J.\ C {\bf 31} (2003) 17 [hep-ex/0307015]. %%CITATION = HEP-EX 0307015;%% %\cite{Aktas:2003sz} \bibitem{Aktas:2003sz} A.~Aktas {\it et al.} [H1 Collaboration], %``Muon pair production in e p collisions at HERA,'' Phys.\ Lett.\ B {\bf 583} (2004) 28 [hep-ex/0311015]. %%CITATION = HEP-EX 0311015;%% %\cite{Abe:2000cv} \bibitem{Abe:2000cv} T.~Abe, %``GRAPE-Dilepton (Version 1.1): A generator for dilepton production in e p collisions,'' Comput.\ Phys.\ Commun.\ {\bf 136} (2001) 126 [hep-ph/0012029]. %%CITATION = HEP-PH 0012029;%% %\cite{Mucke:1999yb} \bibitem{Mucke:1999yb} A.~Mucke, R.~Engel, J.~P.~Rachen, R.~J.~Protheroe and T.~Stanev, %``Monte Carlo simulations of photohadronic processes in astrophysics,'' Comput.\ Phys.\ Commun.\ {\bf 124} (2000) 290 [astro-ph/9903478]. %%CITATION = ASTRO-PH 9903478;%% %\cite{Jung:1993gf} \bibitem{Jung:1993gf} H.~Jung, %``Hard diffractive scattering in high-energy e p collisions and the Monte Carlo generation RAPGAP,'' Comput.\ Phys.\ Commun.\ {\bf 86} (1995) 147. %%CITATION = CPHCB,86,147;%% %\cite{Schuler:yg} \bibitem{Schuler:yg} G.~A.~Schuler and H.~Spiesberger, ``Django: The Interface for The Event Generators Heracles and Lepto.'' %href{http://www.slac.stanford.edu/spires/find/hep/www?irn=2712555}{SPIRES entry} %\cite{Berger:kp} \bibitem{Berger:kp} C.~Berger and P.~Kandel, %``A New Generator For Wide Angle Bremsstrahlung,'' %\href{http://www.slac.stanford.edu/spires/find/hep/www?irn=4270703}{SPIRES entry} Prepared for Workshop on Monte Carlo Generators for HERA Physics Hamburg, Germany, 27-30 Apr 1998. %\cite{Brun:1987ma} \bibitem{Brun:1987ma} R.~Brun, F.~Bruyant, M.~Maire, A.~C.~McPherson and P.~Zanarini, %``Geant3,'' CERN-DD/EE/84-1. %\cite{Andreev:2003pm} \bibitem{Andreev:2003pm} V.~Andreev {\it et al.} [H1 Collaboration], %``Isolated electrons and muons in events with missing transverse momentum at HERA,'' Phys.\ Lett.\ B {\bf 561} (2003) 241 [hep-ex/0301030]. %%CITATION = HEP-EX 0301030;%% %\cite{Adloff:2003uh} %\bibitem{Adloff:2003uh} %C.~Adloff {\it et al.} [H1 Collaboration], %``Measurement and QCD analysis of neutral and charged current cross sections %at HERA,'' %Eur.\ Phys.\ J.\ C {\bf 30}, 1 (2003) %[hep-ex/0304003]. %%CITATION = HEP-EX 0304003;%% \end{thebibliography} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \newpage \begin{table}[] \begin{center} \begin{tabular}{|c|c|c|c|c|} \multicolumn{5}{c}{H1 Multi-lepton analysis HERA I+II (459 pb$^{-1}$, preliminary)}\\ \hline Selection & Data & SM & Pair Production & NC-DIS + Compton \\ \hline ee & 446 & 450 $\pm$ 68 & 375 $\pm$ 42 & 75 $\pm$ 39 \\ $\mu\mu$ & 185 & 194 $\pm$ 38 & 194 $\pm$ 38 & --- \\ e$\mu$ & 201 & 194 $\pm$ 26 & 136 $\pm$ 13 & 58 $\pm$ 17 \\ \hline eee & 81 & 90 $\pm$ 10 & 90 $\pm$ 10 & --- \\ e$\mu\mu$ & 102 & 112 $\pm$ 19 & 112 $\pm$ 19 & --- \\ \hline \end{tabular} \end{center} \caption{Observed and predicted event yields for the ee, $\mu\mu$, e$\mu$, eee and e$\mu\mu$ event classes. The errors on the prediction include model uncertainties and experimental systematic errors added in quadrature.} \label{tab:mlepyields} \end{table} \begin{table}[] \begin{center} \begin{tabular}{|c|c|c|c|c|} \multicolumn{5}{c}{H1 Multi-lepton analysis HERA I+II (preliminary)}\\ \hline Selection & Data & SM & Pair Production & NC-DIS + Compton \\ \hline \multicolumn{5}{c}{$e^+p$ collisions (286 pb$^{-1}$)}\\ \hline ee $M_{12}>$100 GeV & 3 & 1.0 $\pm$ 0.2 & 0.6 $\pm$ 0.2 & 0.4 $\pm$ 0.1 \\ $\mu\mu$ $M_{\mu\mu}>$100 GeV & 0 & 0.06 $\pm$ 0.03 & 0.06 $\pm$ 0.03 & --- \\ e$\mu$ $M_{e\mu}>$100 GeV & 1 & 0.53 $\pm$ 0.05 & 0.53 $\pm$ 0.05 & --- \\ \hline eee $M_{12}>$100 GeV & 3 & 0.6 $\pm$ 0.1 & 0.6 $\pm$ 0.1 & --- \\ e$\mu\mu$ $M_{e\mu}>$100 GeV & 1 & 0.04 $\pm$ 0.02 & 0.04 $\pm$ 0.02 & --- \\ e$\mu\mu$ $M_{\mu\mu}>$100 GeV & 1 & 0.007 $\pm$ 0.005 & 0.007 $\pm$ 0.005 & --- \\ \hline \multicolumn{5}{c}{$e^-p$ collisions (173 pb$^{-1}$)}\\ \hline ee $M_{12}>$100 GeV & 0 & 0.55 $\pm$ 0.1 & 0.3 $\pm$ 0.1 & 0.25 $\pm$ 0.07 \\ $\mu\mu$ $M_{\mu\mu}>$100 GeV & 0 & 0.03 $\pm$ 0.02 & 0.03 $\pm$ 0.02 & --- \\ e$\mu$ $M_{e\mu}>$100 GeV & 0 & 0.3 $\pm$ 0.05 & 0.3 $\pm$ 0.05 & --- \\ \hline eee $M_{12}>$100 GeV & 0 & 0.32 $\pm$ 0.06 & 0.32 $\pm$ 0.06 & --- \\ e$\mu\mu$ $M_{e\mu}>$100 GeV & 0 & 0.04 $\pm$ 0.01 & 0.04 $\pm$ 0.01 & --- \\ e$\mu\mu$ $M_{\mu\mu}>$100 GeV & 0 & 0.006 $\pm$ 0.004 & 0.006 $\pm$ 0.004 & --- \\ \hline \multicolumn{5}{c}{All data (459 pb$^{-1}$)}\\ \hline ee $M_{12}>$100 GeV & 3 & 1.5 $\pm$ 0.3 & 0.9 $\pm$ 0.2 & 0.6 $\pm$ 0.2 \\ $\mu\mu$ $M_{\mu\mu}>$100 GeV & 0 & 0.09 $\pm$ 0.05 & 0.09 $\pm$ 0.05 & --- \\ e$\mu$ $M_{e\mu}>$100 GeV & 1 & 0.9 $\pm$ 0.1 & 0.9 $\pm$ 0.1 & --- \\ \hline eee $M_{12}>$100 GeV & 3 & 0.9 $\pm$ 0.2 & 0.9 $\pm$ 0.2 & --- \\ e$\mu\mu$ $M_{e\mu}>$100 GeV & 1 & 0.1 $\pm$ 0.04 & 0.1 $\pm$ 0.04 & --- \\ e$\mu\mu$ $M_{\mu\mu}>$100 GeV & 1 & 0.03 $\pm$ 0.02 & 0.03 $\pm$ 0.02 & --- \\ \hline % \multicolumn{5}{c}{All data}\\ % \hline % ee $M_{12}>$100 GeV & 3 & 0.61 $\pm$ 0.14 & 0.39 $\pm$ 0.12 & 0.22 $\pm$ 0.06 \\ % $\mu\mu$ $M_{\mu\mu}>$100 GeV & 0 & 0.047 $\pm$ 0.03 & 0.047 $\pm$ 0.03 & --- \\ % e$\mu$ $M_{e\mu}>$100 GeV & 0 & 0.40 $\pm$ 0.04 & 0.40 $\pm$ 0.04 & --- \\ % \hline % eee $M_{12}>$100 GeV & 3 & 0.39 $\pm$ 0.07 & 0.39 $\pm$ 0.07 & --- \\ % e$\mu\mu$ $M_{e\mu}>$100 GeV & 1 & 0.05 $\pm$ 0.015 & 0.05 $\pm$ 0.015 & --- \\ % e$\mu\mu$ $M_{\mu\mu}>$100 GeV & 1 & 0.02 $\pm$ 0.01 & 0.02 $\pm$ 0.01 & --- \\ % \hline \end{tabular} \end{center} \caption{Yields for high di-lepton masses, $M >$ 100 GeV in all analysed samples. For the eee sample, the mass of the two highest $P_T$ electrons is shown. The errors on the prediction include model uncertainties and experimental systematic errors added in quadrature.} \label{tab:mlepyieldsM100} \end{table} \begin{table}[] \begin{center} \begin{tabular}{|c|c|c|c|c|} \multicolumn{5}{c}{H1 Multi-lepton analysis HERA I+II (459 pb$^{-1}$, preliminary)}\\ \hline \multicolumn{5}{|c|}{$\Sigma E_T>$100 GeV}\\ \hline Data sample & Data & SM & Pair Production & NC-DIS + Compton \\ \hline e$^{+}$p (286 pb$^{-1}$) & 4 & 1.2 $\pm$ 0.2 & 1.0 $\pm$ 0.2 & 0.2 $\pm$ 0.1 \\ e$^{-}$p (173 pb$^{-1}$) & 0 & 0.8 $\pm$ 0.2 & 0.6 $\pm$ 0.2 & 0.2 $\pm$ 0.1 \\ All (459 pb$^{-1}$) & 4 & 1.9 $\pm$ 0.4 & 1.5 $\pm$ 0.3 & 0.4 $\pm$ 0.1 \\ \hline \end{tabular} \end{center} \caption{Yields of events with $\sum P_T >$ 100 GeV for the combination of di- and tri-leptons. The errors on the prediction include model uncertainties and experimental systematic errors added in quadrature.} \label{tab:mlepyieldsEt100} \end{table} \begin{figure}[htbp] \begin{center} \includegraphics[width=16cm]{H1prelim-07-062.fig1.eps} \end{center} \caption{Distribution of the invariant mass $M$ of the two leptons compared to expectations for events classified as ee, $\mu\mu$ and e$\mu$. } \label{fig:M2lep} \end{figure} \begin{figure}[htbp] \begin{center} \includegraphics[width=16cm]{H1prelim-07-062.fig2.eps} \end{center} \caption{Distribution of the invariant mass $M_{12}$ of the two highest $P_T$ electrons for the eee sample (top left). For the e$\mu\mu$ sample, invariant mass combinations of the electron with the higest $P_T$ muon ($M_{e\mu}$, bottom left) and of both muons ($M_{\mu\mu}$, top right) are presented. In the tri--lepton channels the background contribution from NC-DIS or Compton events is negligible.} \label{figM3lep} \end{figure} \begin{figure}[htbp] \begin{center} \includegraphics[width=20cm,angle=90]{H1prelim-07-062.fig3.eps} \end{center} \caption{Display of the e$\mu\mu$ event with a scalar sum of transverse momenta of the leptons $\sum P_T >$ 100 GeV, observed in HERA II data.} \label{fig:emumu_evtdisp} \end{figure} \begin{figure}[htbp] \begin{center} \includegraphics[width=16cm]{H1prelim-07-062.fig4.eps} \end{center} \caption{Distributions of the scalar sum of the transverse momenta of the combination of 2 and 3 leptons events compared to expectations for data taken in $e^+p$ (upper left) and $e^-p$ (upper right) collisions. The combination of all HERA data is shown in the bottom figure. } \label{fig:SumEt_All_lep} \end{figure} \clearpage % \begin{table}[] % \begin{center} % \begin{tabular}{|c|c|c|c|c|} % \multicolumn{5}{c}{H1 Preliminary $e^{-}p$ ~2005~ (21 pb$^{-1}$)}\\ % \hline % Selection & Data & SM & Pair Production (GRAPE) & NC-DIS + Compton \\ % \hline % ee & 21 & 21.1 $\pm$ 2.9 & 17.2 $\pm$ 1.9 & 3.9 $\pm$ 1.9 \\ % e$\mu$ & 8 & 10.8 $\pm$ 2.5 & 6.6 $\pm$ 0.6 & 4.2 $\pm$ 2.2 \\ % \hline % eee & 1 & 4.2 $\pm$ 0.7 & 4.2 $\pm$ 0.7 & --- \\ % e$\mu\mu$ & 6 & 5.4 $\pm$ 0.9 & 5.4 $\pm$ 0.9 & --- \\ % \hline % \end{tabular} % \end{center} % \caption{Observed and predicted event yields for the ee, e$\mu$, eee and e$\mu\mu$ event classes. % The analysed data sample corresponds to an integrated luminosity of 21 pb$^{-1}$ of $e^{-}p$ data recorded in 2005. % The errors on the prediction include model uncertainties and experimental systematic errors added in quadrature.} % \label{tab:mlepyields_2005} % \end{table} % % % \begin{figure}[htbp] % \begin{center} % \includegraphics[width=16cm]{figprelimDIS05.eps} % \end{center} % \caption{Distributions of the scalar sum of the transverse momenta of leptons compared to expectations in all two-lepton and three-lepton event classes % and for the combination of both samples. The analysed data sample corresponds to an integrated luminosity of 21 pb$^{-1}$ of $e^{-}p$ data recorded in 2005.} % \label{fig:DIS2005} % \end{figure} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%% General search part .... %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % \clearpage % % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % \section{General Search Analysis} % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % \subsection{Introduction} % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % % The general search for new physics involving high $P_T$ particle production consists of a comprehensive % and generic search for deviations from the SM prediction using all high $P_T$ final state configurations % involving electrons ($e$), muons ($\mu$), jets ($j$), photons % ($\gamma$) or neutrinos ($\nu$). The % analysis covers phase space regions where the SM prediction is % sufficiently precise to detect anomalies and does not rely on % assumptions concerning the characteristics of any SM extension. Such a % model-independent approach may discover unexpected manifestations of % new physics. % % Results obtained with HERA~I data (${\cal L} =$ 115 % pb$^{-1}$) have previously been published~\cite{prelimgen}. The results from the HERA~II data sample (${\cal L} =$ 45 % pb$^{-1}$) are presented here. % % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % \subsection{Analysis of HERA~II Data} % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % % As in the HERA~I analysis, all final states containing at least two % objects ($e$, $\mu$, $j$, $\gamma$, $\nu$) with $P_T >$~$20$~GeV in % the polar angle range $10^\circ < \theta < 140^\circ$ are % investigated. All selected events are classified into exclusive event % classes according to the number and types of objects detected in the % final state, for example $ej$, $\mu j \nu$, $jjjj$. % % Figure~\ref{fig:Nb_tot_gen} shows the yields obtained in the various % event classes. Good agreement with the SM expectation is observed in % all event classes, indicating the good understanding of the SM predictions for HERA and of the H1 detector in the HERA II configuration. The majority of the events observed in the dedicated % multi--lepton and isolated lepton analyses are also selected in this % general analysis. % % % The general search at high $P_T$ gives a global view of the physics % % rates as a function of the final state topology. The future increase % % in luminosity at HERA will benefit all searches for new phenomena at % % high transverse momentum. % % % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % \begin{thebibliography}{99} % % \bibitem{prelimgen} % H1Colaboration, ``General search for new phenomena in $ep$ scattering at HERA''\\ % DESY 04-140, submitted to Phys.Lett. [h1p-ex 0408044] % %http://www-h1.desy.de/h1/www/publications/htmlsplit/H1prelim-03-063.long.html % % \end{thebibliography} % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % % % \begin{figure}[htbp] % \begin{center} % \includegraphics[width=19cm,angle=-90]{H1prelim-05-165.fig5.eps} % \end{center} % \caption{Results of the H1 general search using the new HERA II data (2003-2004). The analysed data sample corresponds to an integrated luminosity of 45 pb$^{-1}$. % The errors on the prediction include model uncertainties and experimental errors added in quadrature. % % The event classes with more than 3 jets are placed in a grey area since their SM prediction suffers from larger theoretical uncertainties. % } % \label{fig:Nb_tot_gen} % \end{figure} \end{document}