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Changeset 561 in svn


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Timestamp:
Apr 5, 2010, 3:46:43 PM (14 years ago)
Author:
Xavier Rouby
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commentaires VL: derniere vague

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trunk/paper/CommPhysComp
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  • trunk/paper/CommPhysComp/notes.tex

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    4949calorimeters and a muon system, and possible very forward detectors arranged
    5050along the beamline.
    51 The framework is interfaced to standard file formats (e.g.\ Les Houches Event File or \texttt{HepMC}) and outputs observables such as isolated leptons, missing transverse energy and collection of jets which can be used for dedicated analyses.
    52 The simulation of the detector response takes into account the effect of magnetic field, the granularity of the calorimeters and subdetector resolutions.
    53 A simplified preselection can also be applied on processed events for trigger emulation. Detection of very forward scattered particles relies on the transport in beamlines with the \textit{Hector} software. Finally, the \textsc{FROG} 2D/3D event display is used for visualisation of the collision final states.
     51The framework is interfaced to standard file formats (e.g.\ Les Houches Event
     52File or \texttt{HepMC}) and outputs observables such as isolated leptons,
     53missing transverse energy and collection of jets which can be used for dedicated
     54analyses. The simulation of the detector response takes into account the effect
     55of magnetic field, the granularity of the calorimeters and subdetector
     56resolutions.
     57A simplified preselection can also be applied on processed events for trigger
     58emulation. Detection of very forward scattered particles relies on the transport
     59in beamlines with the \textit{Hector} software. Finally, the \textsc{FROG} 2D/3D
     60event display is used for visualisation of the collision final states.
    5461\\ \\
    5562
    … …  
    116123
    117124
    118 This complexity can only be handled by large collaborations. Such simulation is
    119 very complicated, technical and requires a large \texttt{CPU} power.
     125This complexity can only be handled by large collaborations. 
    120126Phenomenological studies, looking for the observability of given signals,
    121127require in general only fast but realistic estimates of the expected signal
    … …  
    210216\textsc{ATLAS}), this input parameter file interfaces a flexible parametrisation
    211217for other cases, e.g.\ at future linear colliders~\citep{qr:datacards}.
    212 If no detector card is provided, predefined values based on ``typical''
    213 \textsc{CMS} acceptances and resolutions are used. The geometrical coverage of
    214 the various subsystems used in the default configuration are summarised in
    215 Tab.~\ref{tab:defEta}. The detector is assumed to be strictly symmetric around
    216 the beam axis.
     218The geometrical coverage of the various subsystems used in the default
     219configuration are summarised in Tab.~\ref{tab:defEta}.
    217220
    218221\begin{table}[t]
    … …  
    257260position at which charged particles enter the calorimeters and their
    258261corresponding tracks. The field extension is limited to the tracker volume and
    259 is in particular not applied for muon chambers. Howerver, this is not a limiting
    260 factor as the resolution applied for muon reconstruction is the one expected by
    261 the experiment, which consequently includes the effects of the magnetic field
    262 within the muon system.
     262is in particular not applied for muon chambers. This is not a limiting
     263factor since the magnetic field is not used for the muon momentum smearing.
    263264
    264265
    265266\subsection{Tracks reconstruction}
    266 Every stable charged particle with a transverse momentum above some threshold and lying inside the detector volume covered by the tracker provides a track.
     267Every stable charged particle with a transverse momentum above some threshold
     268and lying inside the detector volume covered by the tracker provides a track.
    267269By default, a track is assumed to be reconstructed with $90\%$ probability if
    268270its transverse momentum $p_T$ is higher than $0.9~\textrm{GeV}/c$ and if its
    269271pseudorapidity $|\eta| \leq 2.5$~\citep{qr:tracks}. No smearing is currently
    270 applied on tracks.
     272applied on track parameters. For each track, the positions at vertex
     273$(\eta,\phi)$ and at the entry point in the calorimeter layers
     274$(\eta,\phi)_{calo}$ are available.
    271275
    272276
    … …  
    280284regions~\citep{bib:cmsjetresolution,bib:ATLASresolution}. It is thus very
    281285important to compute the exact coordinates of the entry point of the particles
    282 into the calorimeters, via the magnetic field calculations.
     286into the calorimeters, in taking the magnetic field effect into account.
    283287
    284288The smallest unit for geometrical sampling of the calorimeters is a
    … …  
    308312where $S$, $N$ and $C$ are the \textit{stochastic}, \textit{noise} and \textit{constant} terms, respectively, and $\oplus$ stands for quadratic additions~\citep{qr:energysmearing}.\\
    309313
    310 In the default parametrisation, ECAL and HCAL are assumed to cover the pseudorapidity range $|\eta|<3$, and FCAL between $3.0$ and $5.0$, with different response to electromagnetic objects ($e^\pm, \gamma$) or hadrons.
    311 Muons and neutrinos are assumed not to interact with the calorimeters~\citep{qr:invisibleparticles}.
    312 The default values of the stochastic, noise and constant terms are given in Tab.~\ref{tab:defResol}.\\
     314In the default parametrisation, ECAL and HCAL are assumed to cover the
     315pseudorapidity range $|\eta|<3$, and FCAL between $3.0$ and $5.0$, with
     316different response to electrons and photons, or to hadrons.
     317Muons and neutrinos are assumed not to interact with the
     318calorimeters~\citep{qr:invisibleparticles}. The default values of the
     319stochastic, noise and constant terms are given in Tab.~\ref{tab:defResol}.\\
    313320
    314321\begin{table}[!h]
    … …  
    336343
    337344
    338 Electrons and photons leave their energy in the electromagnetic parts of the
    339 calorimeters (\textsc{ECAL} and \textsc{FCAL}, e.m.), while charged and neutral
    340 final-state hadrons interact with the hadronic parts (\textsc{HCAL} and
    341 \textsc{FCAL}, had.).
     345Electrons and photons are assumed to leave their energy in the electromagnetic
     346parts of the calorimeters (\textsc{ECAL} and \textsc{FCAL}, e.m.), while charged
     347and neutral final-state hadrons are assumed to leave their entire energy
     348interactin the hadronic parts (\textsc{HCAL} and \textsc{FCAL}, had.).
    342349Some long-living particles, such as the $K^0_s$ and $\Lambda$'s, with lifetime
    343350$c\tau$ smaller than $10~\textrm{mm}$ are considered as stable particles by the
    344 generators although they may decay before the calorimeters. The energy smearing
    345 of such particles is therefore performed using the expected fraction of the
    346 energy, determined according to their decay products, that would be deposited
    347 into the \textsc{ECAL} ($E_{\textsc{ECAL}}$) and into the \textsc{HCAL}
    348 ($E_{\textsc{HCAL}}$). Defining $F$ as the fraction of the energy leading to a
    349 \textsc{HCAL} deposit, the two energy values are given by
     351generators although they may decay before reaching the calorimeters. The energy
     352smearing of such particles is therefore performed using the expected fraction of
     353the energy, determined according to their decay products, that would be
     354deposited into the \textsc{ECAL} ($E_{\textsc{ECAL}}$) and into the
     355\textsc{HCAL} ($E_{\textsc{HCAL}}$). Defining $F$ as the fraction of the energy
     356leading to a \textsc{HCAL} deposit, the two energy values are given by
    350357\begin{equation}
    351358\left\{
    … …  
    356363\right.
    357364\end{equation}
    358 where $0 \leq F \leq 1$. The electromagnetic part is handled similarly as for
    359 electrons and photons. The resulting calorimetry energy measurement given after
    360 the application of the smearing is then $E = E_{\textsc{HCAL}} +
     365where $0 \leq F \leq 1$. The resulting calorimetry energy measurement given
     366after the application of the smearing is then $E = E_{\textsc{HCAL}} +
    361367E_{\textsc{ECAL}}$. For $K_S^0$ and $\Lambda$ hadrons, the energy fraction is
    362368$F$ is assumed to be $0.7$~\citep{qr:emhadratios}.\\
    … …  
    370376(\textsc{MET}), and are used as input for the jet reconstruction algorithms.
    371377
    372 
    373 
    374 
    375 \section{High-level object reconstruction}
    376 
    377378The output file created by \textit{Delphes}~\citep{qr:analysistree} stores the
    378379final collections of particles ($e^\pm$, $\mu^\pm$, $\gamma$) and objects (light
    379 jets, $b$-jets, $\tau$-jets, $E_T^\textrm{miss}$). In addition, some detector
    380 data are added, such as tracks, calorimetric cells and hits in the very forward
    381 detectors (\textsc{ZDC}, \textsc{RP220} and \textsc{FP420}, see
    382 Sec.~\ref{sec:vfd}). While electrons, muons and photons are easily identified,
    383 other quantities are more difficult to evaluate as they rely on sophisticated
    384 algorithms (e.g. jets or missing energy).
     380jets, $b$-jets, $\tau$-jets, $E_T^\textrm{miss}$). In addition, collections of
     381tracks, calorimetric cells and hits in the very forward detectors (\textsc{ZDC},
     382\textsc{RP220} and \textsc{FP420}, see Sec.~\ref{sec:vfd}) are added.
     383
     384\section{High-level reconstruction}
     385
     386While electrons,
     387muons and photons are easily identified, other quantities are more difficult to
     388evaluate as they rely on sophisticated algorithms (e.g. jets or missing energy).
    385389
    386390For most of these objects, their four-momentum and related quantities are
    … …  
    411415collections if they fall into the acceptance of the tracking system and have a
    412416transverse momentum above some threshold (default: $p_T > 10~\textrm{GeV}/c$).
    413 Assuming a good measurement of the track parameters in the real experiment, the
    414 electron energy can be reasonably recovered. \textit{Delphes} assumes a perfect
     417\textit{Delphes} assumes a perfect
    415418algorithm for clustering and Brehmstrahlung recovery. Electron energy is smeared
    416419according to the resolution of the calorimetric cell where it points to, but
    417 independently from any other deposited energy is this cell.
    418 Electrons and photons may create a candidate in the jet collection.
     420independently from any other deposited energy in this cell.
     421Electrons and photons may create a candidate in the jet collection. The $(\eta,
     422\phi)$ position at vertex corresponds to corresponding track vertex.
    419423
    420424\subsubsection*{Muons}
    421425Generator-level muons entering the muon detector acceptance (default: $-2.4
    422 \leq \eta \leq 2.4$) and overpassing some threshold (default : $p_T >
     426\leq \eta \leq 2.4$) and overpassing some threshold (default: $p_T >
    42342710~\textrm{GeV}/c$) are considered as good candidates for analyses.
    424428The application of the detector resolution on the muon momentum depends on a
    425429Gaussian smearing of the $p_T$~\citep{qr:muonsmearing}.
    426 Neither $\eta$ nor $\phi$ variables are modified beyond the calorimeters: no
    427 additional magnetic field is applied. Multiple scattering is neglected. This
    428 implies that low energy muons have in \textit{Delphes} a better resolution than
    429 in a real detector.  At last, the particles which might leak out of the
    430 calorimeters into the muon systems (\textit{punch-through}) are not considered
    431 as muon candidates in \textit{Delphes}.
     430Neither $\eta$ nor $\phi$ variables are modified beyond the calorimeters.
     431Multiple scattering is neglected. This implies that low energy muons have in
     432\textit{Delphes} a better resolution than in a real detector.  At last, the
     433particles which might leak out of the calorimeters into the muon systems
     434(\textit{punch-through}) are not considered as muon candidates in
     435\textit{Delphes}.
    432436
    433437\subsubsection*{Charged lepton isolation}
    … …  
    437441isolation criteria can be applied. This requires that electron or muon
    438442candidates are isolated in the detector from any other particle, within a small
    439 cone. In \textit{Delphes}, charged lepton isolation demands that there is no
    440 other charged particle with $p_T>2~\textrm{GeV}/c$ within a cone of $\Delta R =
    441 \sqrt{\Delta \eta^2 + \Delta \phi^2} <0.5$ centered on the cell associated to
    442 the charged lepton $\ell$, obviously taking the magnetic field into account.
     443cone. In \textit{Delphes}, charged lepton isolation demands by default that
     444there is no other charged particle with $p_T>2~\textrm{GeV}/c$ within a cone of
     445$\Delta R = \sqrt{\Delta \eta^2 + \Delta \phi^2} <0.5$ centered on the cell
     446associated to the charged lepton $\ell$, obviously taking the magnetic field
     447into account.
    443448
    444449The result (i.e.\ \textit{isolated} or \textit{not}) is added to the charged lepton measured properties.
    … …  
    509514In jets, several particle can leave their energy into a given calorimetric cell,
    510515which broadens the jet energy resolution. However, the energy of charged
    511 particles associated to jets can be deduced from their reconstructed track, thus
     516particles associated to jets can be deduced from their associated track, thus
    512517providing a way to identify some of the components of cells with multiple hits.
    513518When the \textit{energy flow} is switched on in \textit{Delphes}, the energy of
    514519tracks pointing to calorimetric cells is subtracted and smeared separately,
    515520before running the chosen jet reconstruction algorithm. This option allows a
    516 better jet $E$ reconstruction~\citep{qr:energyflow}.
     521better jet energy reconstruction~\citep{qr:energyflow}.
    517522 
    518523\subsection{$b$-tagging}
    … …  
    520525
    521526A jet is tagged as $b$-jets if its direction lies in the acceptance of the
    522 tracker and if it is associated to a parent $b$-quark. By default, a $b$-tagging
    523 efficiency of $40\%$ is assumed if the jet has a parent $b$ quark. For $c$-jets
    524 and light jets (i.e.\ originating in $u$, $d$, $s$ quarks or in gluons), a fake
    525 $b$-tagging efficiency of $10 \%$ and $1 \%$ respectively is
    526 assumed~\citep{qr:btag}. The (mis)tagging relies on the identity of
     527tracker and if it is associated to a parent $b$-quark.
     528The (mis)tagging relies on the identity of
    527529the most energetic parton within a cone around the jet axis, with a
    528530radius equal to the one used to reconstruct the jet (default: $\Delta R$ of
    529 $0.7$). In current version of \textit{Delphes}, the displacement of secondary
    530 vertices is not simulated.
    531 
    532 \subsection{\texorpdfstring{$\tau$}{\texttau} identification}
     531$0.7$).
     532By default, a $b$-tagging efficiency of $40\%$ is assumed if the jet has a
     533parent $b$ quark. For $c$-jets and light jets (i.e.\ originating in $u$, $d$,
     534$s$ quarks or in gluons), a fake $b$-tagging efficiency of $10 \%$ and $1 \%$
     535is assumed respectively~\citep{qr:btag}. Therefore, in current version of
     536\textit{Delphes}, the displacement of secondary vertices is not taken into
     537account. As such, the $b$-tagging efficiency is below the expected $40\%$.
     538
     539\subsection{Identification of hadronic \texorpdfstring{$\tau$}{\texttau} decays}
    533540
    534541Jets originating from $\tau$-decays are identified using a procedure consistent
    … …  
    536543The tagging relies on two properties of the $\tau$ lepton. First, $77\%$ of the
    537544$\tau$ hadronic decays contain only one charged hadron associated to a few
    538 neutrals (Tab.~\ref{tab:taudecay}). Secondly, the particles arisen from the
     545neutrals (\textit{1-prong}). Secondly, the particles arisen from the
    539546$\tau$ lepton produce narrow jets in the calorimeter (this is defined as the jet
    540547\textit{collimation}).
    541 
    542 
    543 \begin{table}[!h]
    544 \begin{center}
    545 \caption{ Branching ratios for $\tau^-$ lepton~\citep{bib:pdg}. $h^\pm$ and
    546 $h^0$ refer to charged and neutral hadrons, respectively. $n \geq 0$ and $m \geq
    547 0$ are integers.
    548 \vspace{0.5cm}  }
    549 \begin{tabular}[!h]{lll}
    550 \hline
    551  \multicolumn{3}{l}{\textbf{Leptonic decays}}\\
    552  & $ \tau^- \rightarrow e^- \ \bar \nu_e \ \nu_\tau$ & $17.9\% $ \\
    553  & $ \tau^- \rightarrow \mu^- \ \bar \nu_\mu  \ \nu_\tau$ & $17.4\%$ \\
    554  \multicolumn{3}{l}{\textbf{Hadronic decays}}\\
    555  & $ \tau^- \rightarrow h^-\ (n\times h^\pm) \ (m\times h^0) \  \nu_\tau$  & $64.7\%$ \\
    556  & $ \tau^- \rightarrow h^-\ (m\times h^0) \ \nu_\tau$  & $50.1\%$ \\
    557  & $ \tau^- \rightarrow h^-\ h^+ h^-  (m\times h^0) \ \nu_\tau$  & $14.6\%$ \\
    558 \hline
    559 \end{tabular}
    560 \label{tab:taudecay}
    561 \end{center}
    562 \end{table}
    563548
    564549\begin{figure}[!ht]
    … …  
    622607of tracks associated to particles with significant transverse momenta is one and
    623608only one in a cone of radius $R^\textrm{tracks}$ ($3-$prong $\tau$-jets are
    624 dropped). This cone should be entirely incorporated into the tracker to be taken
    625 into account. Default values of these parameters are given in
     609rejected). This cone should be entirely incorporated into the tracker to be
     610taken into account. Default values of these parameters are given in
    626611Tab.~\ref{tab:tauRef}.
    627612
    … …  
    658643worsens directly the measured missing transverse energy $\overrightarrow
    659644{E_T}^\textrm{miss}$. In \textit{Delphes}, \textsc{MET} is based on the
    660 calorimetric cells only. Muons and neutrinos are therefore not taken into
    661 account for its evaluation:
     645calorimetric cells only. Muons and neutrinos are therefore
     646not taken into account for its evaluation:
    662647\begin{equation}
    663648\overrightarrow{E_T}^\textrm{miss} = - \sum^\textrm{cells}_i \overrightarrow{E_T}(i)
    … …  
    694679\section{\label{sec:vfd}Very forward detector simulation}
    695680
    696 Most of the recent experiments in beam colliders have additional
    697 instrumentation along the beamline. These extend the $\eta$ coverage to higher
    698 values, for the detection of very forward final-state particles. In
    699 \textit{Delphes}, Zero Degree Calorimeters, roman pots and forward taggers have
    700 been implemented (Fig.~\ref{fig:fdets}), similarly as for CMS and
    701 ATLAS collaborations~\citep{bib:cmsjetresolution, bib:ATLASresolution}.
     681Collider experiments often have additional instrumentation along the beamline.
     682These extend the $\eta$ coverage to higher values, for the detection of very
     683forward final-state particles. In \textit{Delphes}, Zero Degree Calorimeters,
     684roman pots and forward taggers have been implemented (Fig.~\ref{fig:fdets}),
     685similarly as for CMS and ATLAS collaborations~\citep{bib:cmsjetresolution,
     686bib:ATLASresolution}.
    702687
    703688\begin{figure}[!ht]
    … …  
    822807
    823808To be able to reach these detectors, particles must have a charge identical to
    824 the beam particles, and a momentum very close to the nominal value of the beam.
    825 These taggers are near-beam detectors located a few millimetres from the true
    826 beam trajectory and this distance defines their acceptance
     809the beam particles, and a momentum very close to the nominal value of the beam
     810particules. These taggers are near-beam detectors located a few millimetres from
     811the true beam trajectory and this distance defines their acceptance
    827812(Tab.~\ref{tab:fdetacceptance}). For instance, roman pots at $220~\textrm{m}$
    828813from the  \textsc{IP} and $2~\textrm{mm}$ from the beam will detect all forward
    829814protons with an energy between $120$ and $900~\textrm{GeV}$~\citep{bib:hector}.
    830 In practice, in the \textsc{LHC}, only positively charged muons ($\mu^+$) and
    831 protons can reach the forward taggers as other particles with a single positive
    832 charge coming from the interaction points will decay before their possible
    833 tagging. In \textit{Delphes}, extra hits coming from the beam-gas events or
     815In \textit{Delphes}, extra hits coming from the beam-gas events or
    834816secondary particles hitting the beampipe in front of the detectors are not taken
    835817into account.
    … …  
    849831these the particle energy ($E$) and the momentum transfer it underwent during
    850832the interaction ($q^2$) can be reconstructed at the analysis level (it is not
    851 implemented in the current versions of \textit{Delphes}. The time-of-flight
     833implemented in the current versions of \textit{Delphes}). The time-of-flight
    852834measurement can be smeared with a Gaussian distribution (default value
    853835$\sigma_t = 0~\textrm{s}$)~\citep{qr:protontaggers}.
    … …  
    868850\textsc{ATLAS}~\citep{bib:ATLASresolution} detectors.
    869851
    870 Electrons and muons are by construction equal to the experiment designs, as the
    871 Gaussian smearing of their kinematics properties is defined according to the
    872 detector specifications. Similarly, the $b$-tagging efficiency (for real
    873 $b$-jets) and misidentification rates (for fake $b$-jets) are taken directly
    874 from the expected values of the experiment. Unlike these simple objects, jets
    875 and missing transverse energy should be carefully cross-checked.
     852Electrons and muons resolutions in \textit{Delphes} match by construction the
     853experiment designs, as the Gaussian smearing of their kinematics properties is
     854defined according to the detector specifications. Similarly, the $b$-tagging
     855efficiency (for real $b$-jets) and misidentification rates (for fake $b$-jets)
     856are taken directly from the expected values of the experiment. Unlike these
     857simple objects, jets and missing transverse energy should be carefully
     858cross-checked.
    876859
    877860\subsection{Jet resolution}
    … …  
    895878The jets made of generator-level particles, here referred as \textit{MC jets},
    896879are obtained by applying the algorithm to all particles considered as stable
    897 after hadronisation (i.e.\ including muons). Jets produced by \textit{Delphes}
     880after hadronisation. Jets produced by \textit{Delphes}
    898881and satisfying the matching criterion are called hereafter \textit{reconstructed
    899882jets}. All jets are computed with the clustering algorithm (JetCLU) with a cone
    … …  
    918901%\includegraphics[width=\columnwidth]{resolutionJet}
    919902\includegraphics[width=\columnwidth]{fig8}
    920 \caption{Resolution of the transverse energy of reconstructed jets $E_T^\textrm{rec}$ as a function of the transverse energy of the closest jet of generator-level particles $E_T^\textrm{MC}$, in a \textsc{CMS}-like detector. The jets events are reconstructed with the JetCLU clustering algorithm with a cone radius of $0.7$. The maximum separation between the reconstructed and \textsc{MC}-jets is $\Delta R= 0.25$. Dotted line is the fit result for comparison to the \textsc{CMS} resolution~\citep{bib:cmsjetresolution}, in blue. The $pp \rightarrow gg$ dijet events have been generated with MadGraph/MadEvent and hadronised with \textit{Pythia}.}
     903\caption{Resolution of the transverse energy of reconstructed jets
     904$E_T^\textrm{rec}$ as a function of the transverse energy of the closest jet of
     905generator-level particles $E_T^\textrm{MC}$, in a \textsc{CMS}-like detector.
     906The jets events are reconstructed with the JetCLU clustering algorithm with a
     907cone radius of $0.7$. The maximum separation between the reconstructed and
     908\textsc{MC}-jets is $\Delta R= 0.25$. Dotted line is the fit result for
     909comparison to the \textsc{CMS} resolution~\citep{bib:cmsjetresolution}, in blue.
     910The $pp \rightarrow gg$ dijet events have been generated with MadGraph/MadEvent
     911and hadronised with \textit{Pythia}.}
    921912\label{fig:jetresolcms}
    922913\end{center}
    923914\end{figure}
    924915
    925 The resulting jet resolution as a function of $E_T^\textrm{MC}$ is shown in Fig.~\ref{fig:jetresolcms}.
     916The resulting jet resolution as a function of $E_T^\textrm{MC}$ is shown in
     917Fig.~\ref{fig:jetresolcms}.
    926918This distribution is fitted with a function of the following form:
    927919\begin{equation}
    … …  
    930922\end{equation}
    931923where $a$, $b$ and $c$ are the fit parameters.
    932 It is then compared to the resolution published by the \textsc{CMS} collaboration~\citep{bib:cmsjetresolution}. The resolution curves from \textit{Delphes} and \textsc{CMS} are in good agreement.
    933 
    934 Similarly, the jet resolution is evaluated for an \textsc{ATLAS}-like detector. The $pp \rightarrow gg$ events are here arranged in $8$ adjacent bins in $p_T$. A $k_T$ reconstruction algorithm with $R=0.6$ is chosen and the maximal matching distance between the \textsc{MC}-jets and the reconstructed jets is set to $\Delta R=0.2$. The relative energy resolution is evaluated in each bin by:
     924It is then compared to the resolution published by the \textsc{CMS}
     925collaboration~\citep{bib:cmsjetresolution}. The resolution curves from
     926\textit{Delphes} and \textsc{CMS} are in good agreement.
     927
     928Similarly, the jet resolution is evaluated for an \textsc{ATLAS}-like detector.
     929The $pp \rightarrow gg$ events are here arranged in $8$ adjacent bins in $p_T$.
     930A $k_T$ reconstruction algorithm with $R=0.6$ is chosen and the maximal matching
     931distance between the \textsc{MC}-jets and the reconstructed jets is set to
     932$\Delta R=0.2$. The relative energy resolution is evaluated in each bin by:
    935933\begin{equation}
    936 \frac{\sigma(E)}{E} = \sqrt{~~ \Bigg \langle ~\Bigg( \frac{E^\textrm{rec} - E^\textrm{MC}}{E^\textrm{rec}} \Bigg)^2 ~ \Bigg \rangle ~ - ~ \Bigg \langle \frac{E^\textrm{rec} - E^\textrm{MC}}{ E^\textrm{rec} } \Bigg \rangle^2}.
     934\frac{\sigma(E)}{E} = \sqrt{~~ \Bigg \langle ~\Bigg( \frac{E^\textrm{rec} -
     935E^\textrm{MC}}{E^\textrm{rec}} \Bigg)^2 ~ \Bigg \rangle ~ - ~ \Bigg \langle
     936\frac{E^\textrm{rec} - E^\textrm{MC}}{ E^\textrm{rec} } \Bigg \rangle^2}.
    937937\end{equation}
    938938
    939 Figure~\ref{fig:jetresolatlas} shows a good agreement between the resolution obtained with \textit{Delphes}, the result of the fit with Equation~\ref{eq:fitresolution} and the corresponding curve provided by the \textsc{ATLAS} collaboration~\citep{bib:ATLASresolution}.
     939Figure~\ref{fig:jetresolatlas} shows a good agreement between the resolution
     940obtained with \textit{Delphes}, the result of the fit with
     941Equation~\ref{eq:fitresolution} and the corresponding curve provided by the
     942\textsc{ATLAS} collaboration~\citep{bib:ATLASresolution}.
    940943
    941944\begin{figure}[!ht]
    942945\begin{center}
    943946\includegraphics[width=\columnwidth]{fig9}
    944 \caption{Relative energy resolution of reconstructed jets as a function of the energy of the closest jet of generator-level particles $E^\textrm{MC}$, in an \textsc{ATLAS}-like detector. The jets are reconstructed with the $k_T$ algorithm with a radius $R=0.6$. The maximal matching distance between \textsc{MC}- and reconstructed jets is $\Delta R=0.2$. Only central jets are considered ($|\eta|<0.5$). Dotted line is the fit result for comparison to the \textsc{ATLAS} resolution~\citep{bib:ATLASresolution}, in blue. The $pp \rightarrow gg$ di-jet events have been generated with MadGraph/MadEvent and hadronised with \textit{Pythia}.}
     947\caption{Relative energy resolution of reconstructed jets as a function of the
     948energy of the closest jet of generator-level particles $E^\textrm{MC}$, in an
     949\textsc{ATLAS}-like detector. The jets are reconstructed with the $k_T$
     950algorithm with a radius $R=0.6$. The maximal matching distance between
     951\textsc{MC}- and reconstructed jets is $\Delta R=0.2$. Only central jets are
     952considered ($|\eta|<0.5$). Dotted line is the fit result for comparison to the
     953\textsc{ATLAS} resolution~\citep{bib:ATLASresolution}, in blue. The $pp
     954\rightarrow gg$ di-jet events have been generated with MadGraph/MadEvent and
     955hadronised with \textit{Pythia}.}
    945956\label{fig:jetresolatlas}
    946957\end{center}
    … …  
    950961\subsection{MET resolution}
    951962 
    952 All major detectors at hadron colliders have been designed to be as much hermetic as possible in order to detect the presence of one or more neutrinos and/or new weakly interacting particles through apparent missing transverse energy.
    953 The resolution of the $\overrightarrow{E_T}^\textrm{miss}$ variable, as obtained with \textit{Delphes}, is then crucial.
    954 
    955 The samples used to study the \textsc{MET} performance are identical to those used for the jet validation.
    956 It is worth noting that the contribution to $E_T^\textrm{miss}$ from muons is negligible in the studied sample.
    957 The input samples are divided in five bins of scalar $E_T$ sums $(\Sigma E_T)$. This sum, called \textit{total visible transverse energy}, is defined as the scalar sum of transverse energy in all cells.
    958 The quality of the \textsc{MET} reconstruction is checked via the resolution on its horizontal component $E_x^\textrm{miss}$.
    959 
    960 The $E_x^\textrm{miss}$ resolution is evaluated in the following way.
    961 The distribution of the difference between $E_x^\textrm{miss}$ in \textit{Delphes} and at generator-level is fitted with a Gaussian function in each $(\Sigma E_T)$ bin. The fit \textsc{RMS} gives the \textsc{MET} resolution in each bin.
    962 The resulting value is plotted in Fig.~\ref{fig:resolETmis} as a function of the total visible transverse
     963All major detectors at hadron colliders have been designed to be as hermetic as
     964possible in order to detect the presence of one or more neutrinos and/or new
     965weakly interacting particles through apparent missing transverse energy.
     966The resolution of the $\overrightarrow{E_T}^\textrm{miss}$ variable, as
     967obtained with \textit{Delphes}, is then crucial.
     968
     969The samples used to study the \textsc{MET} performance are identical to those
     970used for the jet validation. It is worth noting that the contribution to
     971$E_T^\textrm{miss}$ from muons is negligible in the studied sample.
     972The input samples are divided in five bins of scalar $E_T$ sums $(\Sigma E_T)$.
     973This sum, called \textit{total visible transverse energy}, is defined as the
     974scalar sum of transverse energy in all cells. The quality of the \textsc{MET}
     975reconstruction is checked via the resolution on its horizontal component
     976$E_x^\textrm{miss}$.
     977
     978The $E_x^\textrm{miss}$ resolution is evaluated in the following way. The
     979distribution of the difference between $E_x^\textrm{miss}$ in \textit{Delphes}
     980and at generator-level is fitted with a Gaussian function in each $(\Sigma E_T)$
     981bin. The fit \textsc{RMS} gives the \textsc{MET} resolution in each bin.
     982The resulting value is presented in Fig.~\ref{fig:resolETmis} as a function of
     983the total visible transverse
    963984energy, for \textsc{CMS}- and \textsc{ATLAS}-like detectors.
    964985 
    … …  
    968989\includegraphics[width=\columnwidth]{fig10}
    969990\includegraphics[width=\columnwidth]{fig10b}
    970 \caption{$\sigma(E^\textrm{mis}_{x})$ as a function on the scalar sum of all cells ($\Sigma E_T$) for $pp \rightarrow gg$ events, for a \textsc{CMS}-like detector (top) and an \textsc{ATLAS}-like detector (bottom), for di-jet events produced with MadGraph/MadEvent and hadronised with \textit{Pythia}.}
     991\caption{$\sigma(E^\textrm{mis}_{x})$ as a function on the scalar sum of all
     992cells ($\Sigma E_T$) for $pp \rightarrow gg$ events, for a \textsc{CMS}-like
     993detector (top) and an \textsc{ATLAS}-like detector (bottom), for di-jet events
     994produced with MadGraph/MadEvent and hadronised with \textit{Pythia}.}
    971995\label{fig:resolETmis}
    972996\end{center}
    973997\end{figure}
    974998 
    975 The resolution $\sigma_x$ of the horizontal component of \textsc{MET} is observed to behave like
     999The resolution $\sigma_x$ of the horizontal component of \textsc{MET} is
     1000observed to behave like
    9761001\begin{equation}
    9771002\sigma_x = \alpha ~\sqrt{E_T}~~~(\mathrm{GeV}^{1/2}),
    … …  
    9791004where the $\alpha$ parameter depends on the resolution of the calorimeters.
    9801005
    981 The \textsc{MET} resolution expected for the \textsc{CMS} detector for similar events is $\sigma_x = (0.6-0.7) ~ \sqrt{E_T} ~ \mathrm{GeV}^{1/2}$ with no pile-up (i.e. extra simultaneous $pp$ collision occurring at high-luminosity in the same bunch crossing)~\citep{bib:cmsjetresolution}, which compares very well with the $\alpha = 0.63$ obtained with \textit{Delphes}. Similarly, for an \textsc{ATLAS}-like detector, a value of $0.53$ is obtained by \textit{Delphes} for the $\alpha$ parameter, while the experiment expects it in the range $[0.53~ ;~0.57]$~\citep{bib:ATLASresolution}.
     1006The \textsc{MET} resolution expected for the \textsc{CMS} detector for similar
     1007events is $\sigma_x = (0.6-0.7) ~ \sqrt{E_T} ~ \mathrm{GeV}^{1/2}$ with no
     1008pile-up (i.e. extra simultaneous $pp$ collision occurring at high-luminosity in
     1009the same bunch crossing)~\citep{bib:cmsjetresolution}, which compares very well
     1010with the $\alpha = 0.63$ obtained with \textit{Delphes}. Similarly, for an
     1011\textsc{ATLAS}-like detector, a value of $0.53$ is obtained by \textit{Delphes}
     1012for the $\alpha$ parameter, while the experiment expects it in the range $[0.53~
     1013;~0.57]$~\citep{bib:ATLASresolution}.
    9821014
    9831015\subsection{\texorpdfstring{$\tau$}{\texttau}-jet efficiency}
    984 Due to the complexity of their reconstruction algorithm, $\tau$-jets have also to be checked.
    985 Table~\ref{tab:taurecoefficiency} lists the reconstruction efficiencies in \textit{Delphes} for the hadronic $\tau$-jets from $H,Z \rightarrow \tau^+ \tau^-$. The mass of the Higgs boson is set successively to $140$ and $300~\textrm{GeV}/c^2$. The inclusive gauge boson productions  ($pp \rightarrow HX$ and $pp \rightarrow ZX$) are performed with MadGraph/MadEvent and the $\tau$ lepton decay and further hadronisation are handled by \textit{Pythia/Tauola}. All reconstructed $\tau$-jets are $1-$prong, and follow the definition described in section~\ref{btagging}, which is very close to an algorithm of the \textsc{CMS} experiment~\citep{bib:cmstauresolution}. At last, corresponding efficiencies published by the \textsc{CMS} and \textsc{ATLAS} experiments are quoted for comparison. The agreement is good enough at this level to validate the $\tau-$reconstruction.
     1016Table~\ref{tab:taurecoefficiency} lists the reconstruction efficiencies in
     1017\textit{Delphes} for the hadronic $\tau$-jets from $H,Z \rightarrow \tau^+
     1018\tau^-$. The mass of the Higgs boson is set successively to $140$ and
     1019$300~\textrm{GeV}/c^2$. The inclusive gauge boson productions  ($pp \rightarrow
     1020HX$ and $pp \rightarrow ZX$) are performed with MadGraph/MadEvent and the $\tau$
     1021lepton decay and further hadronisation are handled by \textit{Pythia/Tauola}.
     1022All reconstructed $\tau$-jets are $1-$prong, and follow the definition described
     1023in section~\ref{btagging}, which is very close to an algorithm of the
     1024\textsc{CMS} experiment~\citep{bib:cmstauresolution}. At last, corresponding
     1025efficiencies published by the \textsc{CMS} and \textsc{ATLAS} experiments are
     1026quoted for comparison. The level of agreement is satisfactory provided possible
     1027differences due to the event generation chain and the detail of reconstruction
     1028algorithms.
    9861029
    9871030\begin{table}[!h]
    9881031\begin{center}
    989 \caption{Reconstruction efficiencies of $\tau$-jets in $\tau^+ \tau^-$ decays from $Z$ or $H$ bosons, in \textit{Delphes}, \textsc{CMS} and \textsc{ATLAS} experiments~\citep{bib:cmstauresolution,bib:ATLASresolution}. Two scenarios for the mass of the Higgs boson are investigated. Events generated with MadGraph/MadEvent and hadronised with \textit{Pythia}. The decays of $\tau$ leptons is handled by the \textit{Tauola} version embedded in \textit{Pythia}.\vspace{0.5cm}}
    990 %\begin{tabular}{lll}
    991 %\hline
    992 %\multicolumn{2}{c}{\textsc{CMS}} & \\
    993 %$Z \rightarrow \tau^+ \tau^-$                   & $38 \%$ &  \\
    994 %$H \rightarrow \tau^+ \tau^-$ & $36 \%$ & $m_H = 150~\textrm{GeV}/c^2$ \\
    995 %$H \rightarrow \tau^+ \tau^-$ & $47 \%$ & $m_H = 300~\textrm{GeV}/c^2$ \\
    996 %\multicolumn{2}{c}{Delphes} & \\
    997 %$H \rightarrow \tau^+ \tau^-$ &$42 \%$  & $m_H = 140~\textrm{GeV}/c^2$ \\
    998 %\hline
    999 %\end{tabular}
    1000 
     1032\caption{Reconstruction efficiencies of $\tau$-jets in $\tau^+ \tau^-$ decays
     1033from $Z$ or $H$ bosons, in \textit{Delphes}, \textsc{CMS} and \textsc{ATLAS}
     1034experiments~\citep{bib:cmstauresolution,bib:ATLASresolution}. Two scenarios for
     1035the mass of the Higgs boson are investigated. Events generated with
     1036MadGraph/MadEvent and hadronised with \textit{Pythia}. The decays of $\tau$
     1037leptons is handled by the \textit{Tauola} version embedded in
     1038\textit{Pythia}.\vspace{0.5cm}}
    10011039\begin{tabular}{lrlrl}
    10021040\hline
    1003                                 & \textsc{CMS}&Delphes & \textsc{ATLAS}&Delphes         \\
     1041                                & \textsc{CMS}&Delphes & \textsc{ATLAS}&Delphes
     1042\\
    10041043$Z \rightarrow \tau^+ \tau^-$   & $38.2\%$ & $32.4\pm1.8\%$     & $33\%$ & $28.6\pm 1.9\%$              \\
    10051044$H(140) \rightarrow \tau^+ \tau^-$      & $36.3\%$ & $39.9\pm1.6\%$     & & $32.8\pm 1.8\%$             \\
    … …  
    10151054\section{Visualisation}
    10161055
    1017 When performing an event analysis, a visualisation tool is useful to convey information about the detector layout and the event topology in a simple way. The \textit{Fast and Realistic OpenGL Displayer} \textsc{FROG}~\citep{bib:FROG} has been interfaced in \textit{Delphes}, allowing an easy display of the defined detector configuration~\citep{qr:frog}.
    1018 %\footnote{\texttt{[code] } To prepare the visualisation, the \texttt{FLAG\_FROG} parameter should be equal to $1$.}.
    1019  
    1020 % \begin{figure}[!ht]
    1021 % \begin{center}
    1022 % \includegraphics[width=\columnwidth]{Detector_DELPHES_1}
    1023 % \caption{Layout of the generic detector geometry assumed in Delphes. The innermost layer, close to the interaction point, is a central tracking system (pink), embedded into a solenoidal magnetic field.
    1024 % It is surrounded by a central calorimeter volume (green) with both electromagnetic and hadronic sections.
    1025 % The outer layer of the central system (red) consist of a muon system.
    1026 % In addition, two end-cap calorimeters (blue) extend the pseudorapidity coverage of the central detector.
    1027 % The actual detector granularity and extension is defined in the detector card.
    1028 % The detector is assumed to be strictly symmetric around the beam axis (black line).
    1029 % Additional forward detectors are not depicted.}
    1030 % \label{fig:GenDet}
    1031 % \end{center}
    1032 % \end{figure}
    1033  
    1034 Two and three-dimensional representations of the detector configuration can be used for communication purposes, as they clearly illustrate the geometric coverage of the different detector subsystems.
    1035 As an example, the generic detector geometry assumed in this paper is shown in Fig.~\ref{fig:GenDet3}
    1036 %, \ref{fig:GenDet}
    1037  and~\ref{fig:GenDet2}. 
    1038 The extensions of the central tracking system, the central calorimeters and both forward calorimeters are visible. 
    1039 Note that only the geometrical coverage is depicted and that the calorimeter segmentation is not taken into account in the drawing of the detector. Moreover, both the radius and the length of each sub-detectors are just display parameters and are not relevant for the physics simulation.
     1056When performing an analysis, a visualisation tool is useful to convey
     1057information about the detector layout and the event topology in a simple way.
     1058The \textit{Fast and Realistic OpenGL Displayer} \textsc{FROG}~\citep{bib:FROG}
     1059has been interfaced in \textit{Delphes}, allowing an easy display of the defined
     1060detector configuration~\citep{qr:frog}.
     1061 
     1062Two and three-dimensional representations of the detector configuration can be
     1063used for communication purposes, as they clearly illustrate the geometric
     1064coverage of the different detector subsystems.
     1065As an example, the generic detector geometry assumed in this paper is shown in
     1066Fig.~\ref{fig:GenDet3} and~\ref{fig:GenDet2}. The extensions of the central
     1067tracking system, the central calorimeters and both forward calorimeters are
     1068visible. Note that only the geometrical coverage is depicted and that the
     1069calorimeter segmentation is not taken into account in the drawing of the
     1070detector.
    10401071 
    10411072\begin{figure}[!ht]
    … …  
    10431074%\includegraphics[width=\columnwidth]{Detector_DELPHES_2b}
    10441075\includegraphics[width=\columnwidth]{fig11}
    1045 \caption{Layout of the generic detector geometry assumed in \textit{Delphes}. Open 3D-view of the detector with solid volumes. Same colour codes as for Fig.~\ref{fig:GenDet3} are applied. Additional forward detectors are not depicted.}
     1076\caption{Layout of the generic detector geometry assumed in \textit{Delphes}.
     1077Open 3D-view of the detector with solid volumes. Same colour codes as for
     1078Fig.~\ref{fig:GenDet3} are applied. Additional forward detectors are not
     1079depicted.}
    10461080\label{fig:GenDet2}
    10471081\end{center}
    10481082\end{figure}
    10491083 
    1050 Deeper understanding of interesting physics processes is possible by displaying the events themselves.
    1051 The visibility of each set of objects ($e^\pm$, $\mu^\pm$, $\tau^\pm$, jets, transverse missing energy) is enhanced by a colour coding.
    1052 Moreover, kinematics information of each object is visible by a simple mouse action.
    1053 As an illustration, an associated photoproduction of a $W$ boson and a $t$ quark is shown in Fig.~\ref{fig:wt}.
    1054 This corresponds to a $pp(\gamma p \rightarrow Wt)pX$ process, where the $Wt$ couple is induced by an incoming photon emitted by one of the colliding proton~\citep{bib:wtphotoproduction}.
    1055 This leading proton survives after photon emission and is present in the final state.
    1056 As the energy and virtuality of the emitted photon are low, the surviving proton does not leave the beam and escapes from the central detector without being detected.
    1057 The experimental signature is a lack of hadronic activity in the forward hemisphere where the surviving proton escapes.
    1058 The $t$ quark decays into a $W$ boson and a $b$ quark.
    1059 Both $W$ bosons decay into leptons ($W \rightarrow \mu \nu_\mu$ and $W \rightarrow e \nu_e$).
    1060 The balance between the missing transverse energy and the charged lepton pair is clear, as well as the presence of an empty forward region. It is interesting to notice that the reconstruction algorithms build a fake $\tau$-jet around the electron.
     1084Deeper understanding of interesting physics processes is possible by displaying
     1085the events themselves. The visibility of each set of objects ($e^\pm$,
     1086$\mu^\pm$, $\tau^\pm$, jets, transverse missing energy) is enhanced by a colour
     1087coding. Moreover, kinematics information of each object is visible by a simple
     1088mouse action. As an illustration, an associated photoproduction of a $W$ boson
     1089and a $t$ quark~\citep{bib:wtphotoproduction} is shown in Fig.~\ref{fig:wt}.
     1090
     1091% This corresponds to a $pp(\gamma p \rightarrow Wt)pX$ process, where the $Wt$
     1092% couple is induced by an incoming photon emitted by one of the colliding
     1093% proton. This leading proton survives after photon emission and is present in
     1094% the final state. As the energy and virtuality of the emitted photon are low,
     1095% the surviving proton does not leave the beam and escapes from the central
     1096% detector without being detected. The experimental signature is a lack of
     1097% hadronic activity in the forward hemisphere where the surviving proton
     1098% escapes.
     1099% The $t$ quark decays into a $W$ boson and a $b$ quark. Both $W$ bosons decay
     1100% into leptons ($W \rightarrow \mu \nu_\mu$ and $W \rightarrow e \nu_e$). The
     1101% balance between the missing transverse energy and the charged lepton pair is
     1102% clear, as well as the presence of an empty forward region. It is interesting
     1103% to notice that the reconstruction algorithms build a fake $\tau$-jet around
     1104% the electron.
    10611105
    10621106\begin{figure}[!ht]
    … …  
    10641108%%\includegraphics[width=\columnwidth]{Events_DELPHES_1}
    10651109%\includegraphics[width=\columnwidth]{DisplayWt}
    1066 \includegraphics[width=\columnwidth]{fig12}
    1067 \caption{Example of $pp(\gamma p \rightarrow Wt)pY$ event display in different orientations, with $t \rightarrow Wb$.
    1068 One $W$ boson decays into a $\mu \nu_\mu$ pair and the second one into a $e \nu_e$ pair.
    1069 The surviving proton leaves a forward hemisphere with no hadronic activity.
    1070 The isolated muon is shown as the dark blue vector.
    1071 Around the electron, in red, is reconstructed a fake $\tau$-jet (green vector surrounded by a blue cone), while the reconstructed missing energy (in grey) is very small. One jet is visible in one forward region, along the beamline axis, opposite to the direction of the escaping proton.}
     1110\includegraphics[width=0.6\columnwidth]{fig12}
     1111\caption{Example of $pp(\gamma p \rightarrow Wt)pY$ event display in
     1112transverse view, with $t \rightarrow Wb$. One
     1113$W$ boson decays into a $\mu \nu_\mu$ pair and the second one into a $e \nu_e$
     1114pair. The surviving proton leaves a forward hemisphere with no hadronic
     1115activity. The isolated muon is shown as the dark blue vector. Around the
     1116electron, in red, is reconstructed a fake $\tau$-jet (blue cone surrounding a
     1117green arrow). The reconstructed missing energy is visible in grey. }
    10721118\label{fig:wt}
    10731119\end{center}
    10741120\end{figure}
    10751121
    1076 For comparison, Fig.~\ref{fig:gg} depicts an inclusive gluon pair production $pp \rightarrow ggX$.
    1077 The event final state contains more jets, in particular along the beam axis, which is expected as the interacting protons are destroyed by the collision. Two muon candidates and large missing transverse energy are also visible.
     1122For comparison, Fig.~\ref{fig:gg} depicts an inclusive gluon pair production
     1123$pp \rightarrow ggX$. The event final state contains more jets, in particular
     1124along the beam axis, which is expected as the interacting protons are destroyed
     1125by the collision.
    10781126
    10791127\begin{figure}[!ht]
    … …  
    10811129%%\includegraphics[width=\columnwidth]{Events_DELPHES_1}
    10821130%\includegraphics[width=\columnwidth]{Displayppgg}
    1083 \includegraphics[width=\columnwidth]{fig13}
    1084 \caption{Example of inclusive gluon pair production $pp \rightarrow ggX$. Many jets are visible in the event, in particular along the beam axis. Two muons (in blue) are produced and the missing transverse energy is significant in this event (grey vector).}
     1131\includegraphics[width=0.6\columnwidth]{fig13}
     1132\caption{Example of inclusive gluon pair production $pp \rightarrow ggX$. Many
     1133jets are present in the event, in particular along the beam axis (black line).}
    10851134\label{fig:gg}
    10861135\end{center}
    … …  
    10901139\section{Conclusion and perspectives}
    10911140
    1092 % \subsection{version 1}
    1093 % We have described here the major features of the \textit{Delphes} framework, introduced for the fast simulation of a collider experiment.
    1094 % It has already been used for several phenomenological studies, in particular in photon interactions at the \textsc{LHC}.
    1095 %
    1096 % \textit{Delphes} takes the output of event generators, in various formats, and yields analysis-object data.
    1097 % The simulation applies the resolutions of central and forward detectors by smearing the kinematical properties of final state particles.
    1098 % It yields tracks in a solenoidal magnetic field and calorimetric towers.
    1099 % Realistic reconstruction algorithms are run, including the FastJet package, to produce collections of $e^\pm$, $\mu^\pm$, jets and $\tau$-jets. $b$-tag and missing transverse energy are also evaluated.
    1100 % The output is validated by comparing to the \textsc{CMS} expected performances.
    1101 % A trigger stage can be emulated on the output data.
    1102 % At last, event visualisation is possible through the \textsc{FROG} 3D event display.
    1103 %
    1104 %
    1105 % \textit{Delphes} has been developped using the parameters of the \textsc{CMS} experiment but can be easily extended to \textsc{ATLAS} and other non-\textsc{LHC} experiments, as at Tevatron or at the \textsc{ILC}. Further developments include a more flexible design for the subdetector assembly and possibly the implementation of an event mixing module for pile-up event simulation.
    1106 %
    1107 %
    1108 % \subsection{version 2}
    1109 We have described here the major features of the \textit{Delphes} framework, introduced for the fast simulation of a collider experiment. This framework is a tool meant for feasibility studies in phenomenology, gauging the observability of model predictions in collider experiments.
    1110 
    1111 \textit{Delphes} takes as an input the output of event-generators and yields analysis-object data in the form of \texttt{TTree} in a \texttt{*.root} file.
    1112 The simulation includes central and forward detectors to produce realistic observables using standard reconstruction algorithms.
     1141We have described here the major features of the \textit{Delphes} framework,
     1142introduced for the fast simulation of a collider experiment. This framework is a
     1143tool meant for feasibility studies in phenomenology, gauging the observability
     1144of model predictions in collider experiments.
     1145
     1146\textit{Delphes} takes as an input the output of event-generators and yields
     1147analysis-object data in the form of \texttt{TTree} in a \texttt{*.root} file.
     1148The simulation includes central and forward detectors to produce realistic
     1149observables using standard reconstruction algorithms.
    11131150Moreover, the framework allows trigger emulation and 3D event visualisation.
    11141151
    1115 \textit{Delphes} has been developed using the parameters of the \textsc{CMS} experiment but can be easily extended to \textsc{ATLAS} and other non-\textsc{LHC} experiments, as at Tevatron or at the \textsc{ILC}. Further developments include a more flexible design for the subdetector assembly, a better $b$-tag description and possibly the implementation of an event mixing module for pile-up event simulation. This framework has already been used for several analyses~\citep{bib:wtphotoproduction, bib:papierquisortirajamais, bib:papiersimon}, in particular in photon-induced interactions at the \textsc{LHC}.
     1152\textit{Delphes} has been developed using the parameters of the \textsc{CMS}
     1153experiment but can be easily extended to \textsc{ATLAS} and other
     1154non-\textsc{LHC} experiments, as at Tevatron or at the \textsc{ILC}. Further
     1155developments include a more flexible design for the subdetector assembly, a
     1156better $b$-tag description and possibly the implementation of an event mixing
     1157module for pile-up event simulation. This framework has already been used for
     1158several analyses~\citep{bib:wtphotoproduction, bib:papierquisortirajamais,
     1159bib:papiersimon}, in particular in photon-induced interactions at the
     1160\textsc{LHC}.
    11161161
    11171162
    … …  
    11571202R. Kinnunen, A.N. Nikitenko, \textbf{CMS NOTE} \href{http://cdsweb.cern.ch/record/687274}{1997/002}.
    11581203\bibitem{bib:FROG} L. Quertenmont, V. Roberfroid, \textbf{CMS CR} \href{http://cms.cern.ch/iCMS/jsp/openfile.jsp?type=CR&year=2009&files=CR2009_028.pdf}{2009/028}, arXiv:\href{http://arxiv.org/abs/0901.2718}{0901.2718v1}[hep-ex].
    1159 \bibitem{bib:wtphotoproduction} J. de Favereau de Jeneret, S. Ovyn, \textbf{Nucl. Phys. Proc. Suppl.} \href{http://dx.doi.org/10.1016/j.nuclphysbps.2008.07.040}{179-180 (2008)} \href{http://dx.doi.org/10.1016/j.nuclphysbps.2008.07.040}{277-284}; S. Ovyn, J. de Favereau de Jeneret, \href{http://dx.doi.org/10.1393/ncb/i2008-10684-5}{Nuovo Cimento B}, arXiv:0806.4841[hep-ph].
     1204\bibitem{bib:wtphotoproduction} J. de Favereau de Jeneret, S. Ovyn,
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