Changes between Initial Version and Version 1 of GravitonPlusJets


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Timestamp:
03/20/12 16:17:43 (7 years ago)
Author:
trac
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  • GravitonPlusJets

    v1 v1  
     1
     2
     3== Graviton + jets ==
     4=== I. People ===
     5   * Priscila de Aquino,
     6   * Qiang Li,
     7   * Fabio Maltoni,
     8   * Kaoru Hagiwara
     9   * Claude Duhr?
     10
     11=== II. Aim ===
     12
     13To study graviton production through multi-jet final state processes at hadron colliders taking into account the following models: ADD, RS and a massless graviton model. The goal is to compare one model to another considering they are expected to have the same signature.
     14
     15(For RS graviton,we will not consider its decay)
     16
     17=== III. Structure of the Paper ===
     18==== III.1) Introduction ====
     19
     20Small motivation for this work and introduction for each model.
     21==== III.2) Description of the models ====
     22
     232.1 - Definition of each model
     24
     252.2 - Implementation in MG
     26
     272.3 - Choice of parameters (including exclusion limits)
     28==== III.3) Validation of the inclusive samples ====
     29
     303.1 - How the matching is done
     31
     32(In this case, the scale is fixed by the matching, different from the NLO calculation case)
     33
     343.2 - Comparison with Qiang's NLO results
     35
     36(See section V for more information)
     37====== +  ======
     38==== III.4) Results: distributions at the Tevatron and the LHC ====
     39   * Plots to be shown:
     40   * Pt missing (graviton)
     41   * Rapidity (MC level)
     42   * Pt of leading jet
     43   * Pt of 2nd jet
     44   * Ht distribution
     45==== III.5) Conclusions ====
     46
     47---
     48---
     49---
     50
     51=== IV. Event generation: MLM matching ===
     52==== IV.1) General Parameters for the matching: ====
     53
     54'''a) run_card.dat:'''
     55   *
     56      * ickkw=1,
     57      * ktscheme=1 (MLM matching with KT scheme)
     58      * ptj=50 GeV (minimum pt for the jets)
     59      * etaj=4.5 (max rapidity for the jets)
     60      * xqcut=45 GeV
     61      * '''LHC''': Pt grav = 450 GeV (minimum pt for the graviton)
     62      * '''Tevatron''': Pt grav = 120 GeV
     63      * Htjmin = L_MG ("Step function" for the massless_grav case) => '''only for the massless case'''
     64
     65(In order to analyze Pt grav > 500 GeV for the LHC and Pt grav > 150 for the Tevatron, we will fix a lower parameter to generate the events.)
     66====== + <em><strong><br /></strong></em> ======
     67
     68'''b) pythia_card.dat:'''
     69   *
     70      * QCUT=50 GeV
     71
     72'''c) param_card.dat:'''
     73
     74RS - I) For both Tevatron and LHC
     75   *
     76      * M1_grav = 100 GeV (Not physical done only to see how it approaches the massless case)
     77      * L_RS = 3 TeV (limit given in 0909.1587 (fig. 1) and (fig. 2))
     78
     79RS - II) For both Tevatron and LHC
     80   *
     81      * M1_grav = 1 TeV
     82      * L_RS = 3 TeV
     83====== + '''''In the RS model, L_RS=M1_grav/x1/(k/M_Pl) (See Phys.Rev.Lett. 84, 2080 (2000)), x1 is the first root of the Bessel function of order 1, x1~=3.83. Thus from Fig.4 in 0710.3338, for M1_grav=1TeV, L_RS ~&gt;2.6TeV''''' ======
     84
     85Massless graviton) For both Tevatron and LHC
     86   *
     87      * L_MG = 1 TeV
     88
     89ADD)
     90   *
     91      * L_ADD = 5 TeV (LHC), 1 TeV (Tevatron)
     92      * NADD= 2, 4, 6
     93      * Lower mass limit = 0.01 GeV
     94      * Higher mass Limit = L_ADD
     95==== IV.2) Results and Plots ====
     96===== IV.2.1) Matching results (comparison with NLO/LO) =====
     97
     98First we show each matched results via its MatchChecker report. We also show here the comparative plots in which we compare (for each ADD run) the matched result with the NLO/LO result, given the K factor of normalization.
     99====== + a) MatchChecker reports ======
     100<table style="width: 561px; height: 1304px;" cellspacing="1" cellpadding="0" border="1"> <tbody> <tr> <td><strong>Model<br /></strong></td> <td><strong>Parameters<br /></strong></td> <td> '''Name of the Run''' </td> <td><strong>Plots<br /></strong></td> </tr> <tr> <td rowspan="6">ADD</td> <td rowspan="2">
     101
     102L_ADD = 5 TeV
     103
     104NADD = 2
     105</td> <td>ADD_LHC_Run01</td> <td>
     106
     107[attachment:ADD_LHC_Run01_Report.pdf LHC Plots report]
     108</td> </tr> <tr> <td>ADD_Tevatron_Run01</td> <td></td> </tr> <tr> <td rowspan="2">
     109
     110L_ADD = 5 TeV
     111
     112NADD = 4
     113</td> <td>ADD_LHC_Run02</td> <td>
     114
     115[attachment:ADD_LHC_Run02_Report.pdf LHC Plots report]
     116</td> </tr> <tr> <td>ADD_Tevatron_Run02</td> <td><br /></td> </tr> <tr> <td rowspan="2">L_ADD = 5 TeV
     117
     118NADD = 6
     119</td> <td>ADD_LHC_Run03</td> <td>
     120
     121[attachment:ADD_LHC_Run03_Report.pdf LHC Plots report]
     122</td> </tr> <tr> <td>ADD_Tevatron_Run03</td> <td>
     123
     124</td> </tr> <tr> <td rowspan="4">Massless</td> <td rowspan="2">L_MG = 1 TeV</td> <td>Ml_LHC_Run01</td> <td>
     125
     126[attachment:Ml_LHC_Run01_Report.pdf LHC Plots report]
     127</td> </tr> <tr> <td>Ml_Tev_Run01</td> <td> </td> </tr> <tr> <td>L_MG = 2 TeV</td> <td>Ml_LHC_Run02</td> <td>
     128
     129[attachment:Ml_LHC_Run02_Report.pdf LHC Plots report]
     130</td> </tr> <tr> <td>L_MG = 3 TeV</td> <td>Ml_LHC_Run03</td> <td></td> </tr> <tr> <td rowspan="8">RS</td> <td rowspan="2">
     131
     132L_RS = 1TeV
     133
     134M_grav = 1 TeV
     135</td> <td>RS_LHC_Run01</td> <td>[attachment:RS_LHC_Run01_Report.pdf LHC Plots report]</td> </tr> <tr> <td>RS_Tev_Run01</td> <td> </td> </tr> <tr> <td rowspan="2">
     136
     137L_RS = 1 TeV
     138
     139M_grav = 100 GeV
     140</td> <td>RS_LHC_Run02</td> <td>[attachment:RS_LHC_Run02_Report.pdf LHC Plots report]</td> </tr> <tr> <td>RS_Tev_Run02</td> <td> </td> </tr> <tr> <td rowspan="2">
     141
     142L_RS = 3 TeV
     143
     144M_grav = 1 TeV
     145</td> <td>RS_LHC_Run03</td> <td>
     146
     147[attachment:RS_LHC_Run03_Report.pdf LHC Plots report]
     148</td> </tr> <tr> <td>RS_Tev_Run03</td> <td> </td> </tr> <tr> <td rowspan="2">
     149
     150L_RS = 3 TeV
     151
     152M_grav = 100 GeV
     153</td> <td>RS_LHC_Run04</td> <td>
     154
     155[attachment:RS_LHC_Run04_Report.pdf LHC Plots report]
     156</td> </tr> <tr> <td>RS_Tev_Run04</td> <td>
     157
     158</td> </tr> </tbody> </table>
     159
     160====== + b) Comparative plots: NLO/LO & matching results ======
     161
     162|| <p>ADD model</p> || <p>[attachment:Results_LHC_d2.pdf LHC Comparative plot (PtGrav) for d=2]</p> <p>[attachment:Results_LHC_d4.pdf LHC Comparative plot (PtGrav) for d=4]</p> <p>[attachment:Results_LHC_d6.pdf LHC Comparative plot (PtGrav) for d=6]</p> <p> </p> <p>[attachment:Results_LHC_ADD.pdf LHC combined comparative plot]</p> ||
     163|| || ||
     164|| Massless grav. model || <p>[attachment:Results_LHC_Ml.pdf LHC combined comparative plot]</p> <p> </p> ||
     165|| || ||
     166|| RS model || <p> </p> <p>[attachment:Results_LHC_RS.pdf LHC combined comparative plot]</p> <p> </p> ||
     167====== + c) Jet Rates for the LHC samples ======
     168
     169|| <p>ADD model</p> || <p>[attachment:JetRates_ADD.pdf Jet rates]</p> ||
     170|| || ||
     171|| Massless grav. model || <p>[attachment:JetRates_Ml.pdf Jet rates]</p> ||
     172|| || ||
     173|| RS model || <p>[attachment:JetRates_RS.pdf Jet rates]</p> ||
     174
     175PS. The number of events is normalized by the total number of events of each run.
     176===== IV.2.2) Study on the shape of the curves (Pt grav) related to the mass of the graviton =====
     177
     178Particularly for the RS model, we can see that the slope of the curve changes with the mass of the graviton (for example, compare RS with L_{RS}{{{3TeV/M_{grav} }}} 1 TeV against L_{RS}{{{3TeV/M_grav }}} 100 GeV). That is related to the fact we are plotting the pt of the graviton. The harder is the emission, the more inclined the curve will be.
     179
     180For the RS model is easy to see, because we can control the graviton mass (considering it is an input in this case). For the ADD it is a bit harder because the graviton should be an integration of the KK states. However, we know that the mass density depends on the number of extra dimensions. Therefore, we should have a different slope for each curve given its number of extra dimensions (d=2,4,6).
     181
     182The problem is that the difference of the slopes will not be large enough that it could be recognized from the pt of the graviton plot. Nevertheless, for the ADD model in MG, the graviton decays into 2 fake particles: x1 and x2. Hence, if we plot the invariant mass of x1 and x2 for each d=2,4,6 ([attachment:ADD_InvMassGrav.pdf Plot]), we could infeer the difference of the slope through the difference of mass density, showing the same physical behavior for both theories.
     183
     184==== IV.3) Plan ====
     185===== IV.3.1) What we already have =====
     186===== IV.3.2) What is being taken care of =====
     187===== IV.3.3) What is missing =====
     188==== IV.3) To be discussed on our next meeting ====
     189
     1901) How to present the comparison of matching results with NLO/LO ones? (how to show that the difference on the k factors comes from the different techniques of computing the graviton emission?)
     191
     192Qiang: I think the comparison can be seen as just another validation way, in the sense that the MLM matched curve should lie inside the uncertainty band of the NLO one, after appropriate adaptation of normalization. And then further the MLM matching can give us more information such as 2nd/3rd jet distribution and jet rates, which the NLO calculation to G+J can not present
     193
     1942) Confirmation of the plots we both should have: pt graviton, pt leading jet, pt 2nd jet, Ht distribution, rapidity
     195
     1963) For the RS and massless model, the cuts for searching at the LHC and Tevatron are the same as for the ADD model, it is fine, right?
     197
     1984) Since ADD model is only an effective model, the results we get are valid only as long as the scales involved in the hard scattering process do not exceed the fundamental scale, we need to quantify the sensitivity of our prediction to the unknown UV completion of the theory. Should we do this?
     199
     2005) Does matching can give reliable results for total cross section or not? Or just for shape/distribution?<br />It seems the total cross section after matching is definitely not the same as G+0jet's, or G+njet's. So what is the meaning of the matched total cross section?
     201
     202---
     203---
     204---
     205
     206=== V. Qiang's NLO results ===
     207
     208For reference, the cuts in 0911.5095 (NLO QCD corrections to G+monojet) are the following:
     209
     210   * '''LHC''': PTmiss&gt;500GeV; ||\eta_j||&lt;4.5
     211   * '''Tevatron''': PTmiss&gt;120GeV; harder jet : Ptj&gt;150GeV with ||\eta_j||&lt;1; softer jet with PT&gt;60GeV, ||\eta_j||&lt;3.6 is vetoed.
     212
     213   * mur=muf= Pt graviton
     214   * 5 quark flavors considered
     215   * MSTW2008LO/NLO for LO/NLO results *(Will be changed to CTEQ6L1/6M for comparison)*
     216====== A question on comparing matched results with the NLO ones: ======
     217
     218'''In the NLO work, indeed different jet algorithm from the one chosen in MG/ME is used, see the jet definition on page 5 of 0911.5095:'''
     219<blockquote>
     220
     221   * <p> '''For the LHC, "the jets are defined by the K_T algorithm with D=0.6, and are required to satisfy ||\eta_j||&lt;4.5 and PTj&gt;50GeV"''' </p>
     222   * <p> '''For the Tevatron,"jets are defined by the K_T algorithm with D=0.7, and are required to satisfy ||\eta_j||&lt;3.6 and PTj&gt;20GeV"''' </p>
     223</blockquote>
     224
     225'''Here D is just the jet cone separation Drjj, so should we set Drjj cut futher to the matched results, in order to compare with the NLO ones?'''
     226
     227In the matching procedure, the separation between jets is defined by the xqcut and pythia's QCUT parameters. We have to set Drjj to zero in the run_card.dat.
     228
     229<strong><br /></strong>
     230=== VI. References ===
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