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--- 2013:groups:tools:substructure [2013/06/05 18:28]
loch.peter [Signal samples]
+++ 2013:groups:tools:substructure [2013/06/07 15:46] (current)
andy.buckley [Software version 1] Link to Bitbucket, etc.
@@ Line 17: / Line 17: @@
 ===== Signal samples =====
-The following signal samples were discussed:
+The following signal samples are discussed:
   - Final states with boosted objects:
-    - _signal_ : boosted top in  $t\bar{t}$  ( $\hat{p}_{T} > 200(450) {\rm\ GeV}$ ); full hadronic ok;
+    - boosted top in  $t\bar{t}$  ( $\hat{p}_{T} > 200(450) {\rm\ GeV}$ ); full hadronic ok;
-    - _background_ : inclusive jets in similar phase space as  $t\bar{t}$ ;
+    - inclusive jets in similar phase space as  $t\bar{t}$ ;
+    -  $HZ\to b\bar{b} \nu\nu$  with  $H(125)$ ; boosted  $b\bar{b}$  system and large  $E_{\rm T}^{\rm miss}$ ;
   - VBS/VBF with (not boosted) tag jets
     - WW/ZZ/WZ continuum, high  $M_{WW/​ZZ/​WZ} > 1 {\rm\ TeV}$  (may be not possible in Pythia8 - maybe have to go for a high mass Higgs-like particle?)
@@ Line 30: / Line 31: @@
-===== Configurations =====
+===== Configurations & Software =====
+The following configurations for the (average) number of pile-up interactions  $\langle\mu\rangle$  are suggested
+ $\langle\mu\rangle = \{ 30, 60, 120, 240 \}$
+The actual number of pile-up interactions added to the signal event is taken from a Poisson distribution around  $\langle\mu\rangle$ .
+==== Software version 1 ====
+Pile-up can be added dynamically using Peter's eventmanager software. All the software for the LH pile-up/substructure studies is being developed through a [[https://bitbucket.org/andybuckley/lh2013pileup/overview|Bitbucket repository]]: you can check out without an account. Send a request for access if you want to commit (push) to the main code repository.
+(Previous version of software as a {{:2013:groups:tools:anal02.tar.gz| tarball}}.)
+The main concept here is that the ROOT based raw data is converted into an ''Event'' object containing lists of ''PseudoJet''s (from ''Fastjet'') representing
+  * the total particle (hadron) level event (signal + pile-up)
+  * the particle (hadron) level signal event
+  * the particle (hadron) level pile-up event
+The code is not very convenient to use in this version. On most systems I expect a
+<code>make all</code> should work to compile the library and the example in ''anal02.C''.  For implementing your own analysis, please check the ''anal02.C'' and ''Zprime_Py8::analyze(Event& rEvt)'' (your playground) in ''Zprime_Py8.C'' as examples. The program supports a few command line arguments
+<code>
+anal02.exe --help --mu=<mu> --nevts=<number of (signal) events>
+           --sigflist=<text file with list of signal files>
+           --puflist=<text file with list of pile-up files>
+</code>
+Some hints:
+  * ''--help'' prints a brief usage instruction (which I think is not up-to-date, so please ignore!)
+  * ''--mu=<mu>'' expects the number of interactions per event. if ''<mu> < 0'', exactly ''|<mu>|'' interactions are collected into one event. ''<mu> > 0'' means a Poisson-distributed number of pile-up interactions will be collected from the pile-up (minimum bias) event samples.
+    * if you specify both signal and pile-up input, ''<mu>'' should be the number of pile-up events to be added to one signal event
+  * ''--sigflist=<file>'' specifies a text file (no "" around file name!) with a list of signal files to be processed. If this list is not given, ''Zprime_Py8::analyze(...)'' will not be invoked.
+  * ''--puflist=<file>'' specifies a text file (no "" around file name!) with a list of pile-up files to be processed. If this list is not given, only signal events are analyzed (you should set ''--mu=1'' in this case!).
 ===== Methods =====
+The idea is to test filtering/grooming techniques as a way to reduce the sensiticity to bsoft backgrounds (initially the filter used with the BDRS tagger was meant to reduce the sensitivity to the UE).
+Following the Filter tool in FastJet3, we need (i) a jet definition to break the jet into subjets and (ii) a selection criterion that decides what subjets are kept. We'll consider 3 options:
+  * "Filtering":
+    * cluster with Cambridge/Aachen,  $R_{\rm filt} = \eta_{\rm filt} R_{\rm jet}$  [ $\eta_{\rm filt}$  between 1/3 and 1/2 sounds about right]
+    * keep the  $n_{\rm filt}$  hardest subjets [ $n_{\rm filt}$ =2.3.4]
+  * "Trimming":
+    * cluster with Cambridge/Aachen,  $R_{\rm filt} = 0.2$
+    * keep all subjets with  $p_{t,\rm sub} > f p_{t,jet}$  [ $f$  between 0.01 and 0.05 should be fine]
+  * "Area-filtering":
+    * cluster with Cambridge/Aachen,  $R_{\rm filt} = 0.2$
+    * keep all subjets with  $p_{t,\rm sub} > \rho A_{\rm sub} + n \sigma \sqrt{A_{\rm sub}}$  [ $n$  between 2 and 5]
+The 3rd option is new and based on the idea that the PU scales  $\rho$  and  $\sigma$  should set the scale of the PU/noise removal.
+For pileup sutraction, one usually want to first subtract the average PU contamination ( $\rho A_{\rm sub}$ ) from each subjet before deciding which subjets are to be kept. This is implemented in the fastjet::Filter. Note that with "Area-filtering" you should then cut with    $p_{t,​\rm sub} > n \sigma \sqrt{A_{\rm sub}}$  since the baseline has already been subtracted.

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