Difference: LightQuarkEta (1 vs. 47)

Revision 47
Changes from r45 to r47
Line: 1 to 1
 
META TOPICPARENT name="NloStudies"

Studies of the light quark pseudorapidity distribution in t-channel single top

At the Tevatron, the t-channel single top quark signal has a very nice variable that can be exploited to separate the single top quark signal from the backgrounds. The light quark, also called spectator quark, that is scattered in the t-channel exchange of a W boson typically goes in the forward direction. The corresponding variable is called Q*Eta. In this variable, the pseudorapidity of the leading non-b-tagged jet is multiplied by Q, the charge of the lepton (i.e. the charge of the top quark). The distribution is peaked in the forward direction, at a pseudorapidity of about 1.5 to 2. The plot below shows this variable, this is from a study of Tevatron t-channel single top quark production
Line: 13 to 13
 

ONETOP

The light quark pseudorapidity distribution isn't expected to change much when going from LO to NLO. Shown below is the output from the ONETOP program, comparing the light quark jet eta distribution between leading order and NLO.
Changed:
<
<
ONETOP_QEta
>
>
ONETOP_QEta
 

MCFM

Here we show the results of a quick study using MCFM. In this study, the top quark mass was set to 175GeV, and the same value was chosen for factorization and renormalization scales. The CTEQ6M PDF set was chosen. Both top and antitop quark production is included. With these settings, the total cross section at NLO for top quark production only is 150pb, and that for antitop production is 109pb. Note that MCFM uses massless b-quarks for s-channel and t-channel single top.
Revision 45
Changes from r43 to r45
Line: 1 to 1
 
META TOPICPARENT name="NloStudies"

Studies of the light quark pseudorapidity distribution in t-channel single top

At the Tevatron, the t-channel single top quark signal has a very nice variable that can be exploited to separate the single top quark signal from the backgrounds. The light quark, also called spectator quark, that is scattered in the t-channel exchange of a W boson typically goes in the forward direction. The corresponding variable is called Q*Eta. In this variable, the pseudorapidity of the leading non-b-tagged jet is multiplied by Q, the charge of the lepton (i.e. the charge of the top quark). The distribution is peaked in the forward direction, at a pseudorapidity of about 1.5 to 2. The plot below shows this variable, this is from a study of Tevatron t-channel single top quark production
Line: 7 to 7
  tevQEtaSmall.png
Changed:
<
<

MCFM, LHC, Atlas

>
>

LHC, Atlas

  At the LHC the situation is different. First, the initial beam is proton-proton rather than proton-antiproton. Thus, every distribution is symmetric in eta, and selecting events by charge of the lepton doesn't make any difference. Second, the initial beam energy is much higher, and top quarks are produced farther away from threshold and hence experience the top quark and the light quark jet will be more central.
Added:
>
>

ONETOP

The light quark pseudorapidity distribution isn't expected to change much when going from LO to NLO. Shown below is the output from the ONETOP program, comparing the light quark jet eta distribution between leading order and NLO. ONETOP_QEta

MCFM

  Here we show the results of a quick study using MCFM. In this study, the top quark mass was set to 175GeV, and the same value was chosen for factorization and renormalization scales. The CTEQ6M PDF set was chosen. Both top and antitop quark production is included. With these settings, the total cross section at NLO for top quark production only is 150pb, and that for antitop production is 109pb. Note that MCFM uses massless b-quarks for s-channel and t-channel single top.

MCFM output, no cuts

Revision 43
Changes from r41 to r43
Line: 1 to 1
 
META TOPICPARENT name="NloStudies"

Studies of the light quark pseudorapidity distribution in t-channel single top

At the Tevatron, the t-channel single top quark signal has a very nice variable that can be exploited to separate the single top quark signal from the backgrounds. The light quark, also called spectator quark, that is scattered in the t-channel exchange of a W boson typically goes in the forward direction. The corresponding variable is called Q*Eta. In this variable, the pseudorapidity of the leading non-b-tagged jet is multiplied by Q, the charge of the lepton (i.e. the charge of the top quark). The distribution is peaked in the forward direction, at a pseudorapidity of about 1.5 to 2. The plot below shows this variable, this is from a study of Tevatron t-channel single top quark production
Line: 54 to 54
  and separated from the other objects in the event. Below are the two relevant distributions: * t-channel light quark eta distribution at NLO, but only for 2-jet events:
Changed:
<
<
mcfm_tq_EtaLQ_2j_nocuts.png
>
>
mcfm_tq_EtaLQ_2j_nocuts.png
 
  • t-channel light quark eta distribution at NLO, but only for 3-jet events:
    mcfm_tq_EtaLQ_3j_nocuts.png
Added:
>
>
It is clear from these distributions that the real gluon emission diagrams are responsible for the flattening out of the eta distribution of the light quark jet.
 

-- ReinhardSchwienhorst - 06 Apr 2007 -- ReinhardSchwienhorst - 13 Apr 2007
Revision 41
Changes from r39 to r41
Line: 1 to 1
 
META TOPICPARENT name="NloStudies"

Studies of the light quark pseudorapidity distribution in t-channel single top

At the Tevatron, the t-channel single top quark signal has a very nice variable that can be exploited to separate the single top quark signal from the backgrounds. The light quark, also called spectator quark, that is scattered in the t-channel exchange of a W boson typically goes in the forward direction. The corresponding variable is called Q*Eta. In this variable, the pseudorapidity of the leading non-b-tagged jet is multiplied by Q, the charge of the lepton (i.e. the charge of the top quark). The distribution is peaked in the forward direction, at a pseudorapidity of about 1.5 to 2. The plot below shows this variable, this is from a study of Tevatron t-channel single top quark production
Line: 46 to 46
  lord_tq_EtaLQ_cuts.png
Added:
>
>

Distributions separated by jet multiplicity

The light quark jet pseudorapidity distribution shows a peak in the forward direction at leading order. Here we check whether that peak is still visible if we use the NLO distribution, but restrict ourselves to 2-jet events. Shown below are is the eta distribution of the light quark jet at NLO, but separately for 2-jet events and 3-jet events. The 2-jet events are made up of LO events, events with virtual corrections, and events with real gluon emission for which the gluon (or b-quark) momentum was low or absorbed into one of the other quark jets. Conversely, 3-jet events are produced when the additional gluon (or jet) radiation is a high momentum so that it will be reconstructed and separated from the other objects in the event. Below are the two relevant distributions: * t-channel light quark eta distribution at NLO, but only for 2-jet events:
mcfm_tq_EtaLQ_2j_nocuts.png

  • t-channel light quark eta distribution at NLO, but only for 3-jet events:
    mcfm_tq_EtaLQ_3j_nocuts.png
  -- ReinhardSchwienhorst - 06 Apr 2007 -- ReinhardSchwienhorst - 13 Apr 2007

Deleted:
<
<
  • t-channel light quark eta distribution at NLO, but only for 2-jet events:
    mcfm_tq_EtaLQ_2j_nocuts.png
 
Deleted:
<
<
  • t-channel light quark eta distribution at NLO, but only for 3-jet events:
    mcfm_tq_EtaLQ_3j_nocuts.png
 

META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution from MCFM, before any cuts" date="1176496171" name="mcfm_tq_EtaLQ_nocuts.png" path="mcfm_tq_EtaLQ_nocuts.png" size="29752" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution at NLO, but only for 2-jet events" date="1176495948" name="mcfm_tq_EtaLQ_2j_nocuts.png" path="mcfm_tq_EtaLQ_2j_nocuts.png" size="28889" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution from MCFM, after Atlas-style cuts" date="1176496213" name="mcfm_tq_EtaLQ_Atlcuts.png" path="mcfm_tq_EtaLQ_Atlcuts.png" size="25227" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark jet pT distribution from MCFM, before any cuts" date="1176404620" name="lqjetpt.png" path="lqjetpt.png" size="23531" user="Main.ReinhardSchwienhorst" version=""
Changed:
<
<
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution at LO, after Atlas-style cuts" date="1176475522" name="lord_tq_EtaLQ_cuts.png" path="lord_tq_EtaLQ_cuts.png" size="33273" user="Main.ReinhardSchwienhorst" version=""
>
>
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution at LO, after Atlas-style cuts" date="1176496443" name="lord_tq_EtaLQ_cuts.png" path="lord_tq_EtaLQ_cuts.png" size="28109" user="Main.ReinhardSchwienhorst" version=""
 
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution at NLO, but only for 3-jet events" date="1176495884" name="mcfm_tq_EtaLQ_3j_nocuts.png" path="mcfm_tq_EtaLQ_3j_nocuts.png" size="28454" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="Q*Eta distribution in t-channel single top at the Tevatron, from our MSU NLO study" date="1175887451" name="tevQEtaSmall.png" path="tevQEtaSmall.png" size="5236" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark jet pT distribution from MCFM, after Atlas-style cuts" date="1176404716" name="lqjetpt_aftercuts.png" path="lqjetpt_aftercuts.png" size="20738" user="Main.ReinhardSchwienhorst" version=""
Changed:
<
<
META FILEATTACHMENT attachment="lord_tq_EtaLQ_nocuts.png" attr="h" comment="t-channel light quark eta distribution at LO, before any cuts" date="1176496414" name="lord_tq_EtaLQ_nocuts.png" path="lord_tq_EtaLQ_nocuts.png" size="22336" stream="lord_tq_EtaLQ_nocuts.png" user="Main.ReinhardSchwienhorst" version="0"
>
>
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution at LO, before any cuts" date="1176496414" name="lord_tq_EtaLQ_nocuts.png" path="lord_tq_EtaLQ_nocuts.png" size="22336" user="Main.ReinhardSchwienhorst" version=""
Revision 39
Changes from r37 to r39
Line: 1 to 1
 
META TOPICPARENT name="NloStudies"

Studies of the light quark pseudorapidity distribution in t-channel single top

At the Tevatron, the t-channel single top quark signal has a very nice variable that can be exploited to separate the single top quark signal from the backgrounds. The light quark, also called spectator quark, that is scattered in the t-channel exchange of a W boson typically goes in the forward direction. The corresponding variable is called Q*Eta. In this variable, the pseudorapidity of the leading non-b-tagged jet is multiplied by Q, the charge of the lepton (i.e. the charge of the top quark). The distribution is peaked in the forward direction, at a pseudorapidity of about 1.5 to 2. The plot below shows this variable, this is from a study of Tevatron t-channel single top quark production
Line: 56 to 56
 
  • t-channel light quark eta distribution at NLO, but only for 3-jet events:
    mcfm_tq_EtaLQ_3j_nocuts.png
Changed:
<
<
META FILEATTACHMENT attachment="mcfm_tq_EtaLQ_nocuts.png" attr="h" comment="t-channel light quark eta distribution from MCFM, before any cuts" date="1176496171" name="mcfm_tq_EtaLQ_nocuts.png" path="mcfm_tq_EtaLQ_nocuts.png" size="29752" stream="mcfm_tq_EtaLQ_nocuts.png" user="Main.ReinhardSchwienhorst" version="0"
>
>
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution from MCFM, before any cuts" date="1176496171" name="mcfm_tq_EtaLQ_nocuts.png" path="mcfm_tq_EtaLQ_nocuts.png" size="29752" user="Main.ReinhardSchwienhorst" version=""
 
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution at NLO, but only for 2-jet events" date="1176495948" name="mcfm_tq_EtaLQ_2j_nocuts.png" path="mcfm_tq_EtaLQ_2j_nocuts.png" size="28889" user="Main.ReinhardSchwienhorst" version=""
Changed:
<
<
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution from MCFM, after Atlas-style cuts" date="1175886537" name="mcfm_tq_EtaLQ_Atlcuts.png" path="mcfm_tq_EtaLQ_Atlcuts.png" size="29054" user="Main.ReinhardSchwienhorst" version=""
>
>
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution from MCFM, after Atlas-style cuts" date="1176496213" name="mcfm_tq_EtaLQ_Atlcuts.png" path="mcfm_tq_EtaLQ_Atlcuts.png" size="25227" user="Main.ReinhardSchwienhorst" version=""
 
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark jet pT distribution from MCFM, before any cuts" date="1176404620" name="lqjetpt.png" path="lqjetpt.png" size="23531" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution at LO, after Atlas-style cuts" date="1176475522" name="lord_tq_EtaLQ_cuts.png" path="lord_tq_EtaLQ_cuts.png" size="33273" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution at NLO, but only for 3-jet events" date="1176495884" name="mcfm_tq_EtaLQ_3j_nocuts.png" path="mcfm_tq_EtaLQ_3j_nocuts.png" size="28454" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="Q*Eta distribution in t-channel single top at the Tevatron, from our MSU NLO study" date="1175887451" name="tevQEtaSmall.png" path="tevQEtaSmall.png" size="5236" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark jet pT distribution from MCFM, after Atlas-style cuts" date="1176404716" name="lqjetpt_aftercuts.png" path="lqjetpt_aftercuts.png" size="20738" user="Main.ReinhardSchwienhorst" version=""
Changed:
<
<
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution at LO, before any cuts" date="1176475490" name="lord_tq_EtaLQ_nocuts.png" path="lord_tq_EtaLQ_nocuts.png" size="24476" user="Main.ReinhardSchwienhorst" version=""
>
>
META FILEATTACHMENT attachment="lord_tq_EtaLQ_nocuts.png" attr="h" comment="t-channel light quark eta distribution at LO, before any cuts" date="1176496414" name="lord_tq_EtaLQ_nocuts.png" path="lord_tq_EtaLQ_nocuts.png" size="22336" stream="lord_tq_EtaLQ_nocuts.png" user="Main.ReinhardSchwienhorst" version="0"
Revision 37
Changes from r35 to r37
Line: 1 to 1
 
META TOPICPARENT name="NloStudies"

Studies of the light quark pseudorapidity distribution in t-channel single top

At the Tevatron, the t-channel single top quark signal has a very nice variable that can be exploited to separate the single top quark signal from the backgrounds. The light quark, also called spectator quark, that is scattered in the t-channel exchange of a W boson typically goes in the forward direction. The corresponding variable is called Q*Eta. In this variable, the pseudorapidity of the leading non-b-tagged jet is multiplied by Q, the charge of the lepton (i.e. the charge of the top quark). The distribution is peaked in the forward direction, at a pseudorapidity of about 1.5 to 2. The plot below shows this variable, this is from a study of Tevatron t-channel single top quark production
Line: 56 to 56
 
  • t-channel light quark eta distribution at NLO, but only for 3-jet events:
    mcfm_tq_EtaLQ_3j_nocuts.png
Changed:
<
<
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution from MCFM, before any cuts" date="1175886282" name="mcfm_tq_EtaLQ_nocuts.png" path="mcfm_tq_EtaLQ_nocuts.png" size="28288" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution at NLO, but only for 2-jet events" date="1176494892" name="mcfm_tq_EtaLQ_2j_nocuts.png" path="mcfm_tq_EtaLQ_2j_nocuts.png" size="33148" user="Main.ReinhardSchwienhorst" version=""
>
>
META FILEATTACHMENT attachment="mcfm_tq_EtaLQ_nocuts.png" attr="h" comment="t-channel light quark eta distribution from MCFM, before any cuts" date="1176496171" name="mcfm_tq_EtaLQ_nocuts.png" path="mcfm_tq_EtaLQ_nocuts.png" size="29752" stream="mcfm_tq_EtaLQ_nocuts.png" user="Main.ReinhardSchwienhorst" version="0"
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution at NLO, but only for 2-jet events" date="1176495948" name="mcfm_tq_EtaLQ_2j_nocuts.png" path="mcfm_tq_EtaLQ_2j_nocuts.png" size="28889" user="Main.ReinhardSchwienhorst" version=""
 
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution from MCFM, after Atlas-style cuts" date="1175886537" name="mcfm_tq_EtaLQ_Atlcuts.png" path="mcfm_tq_EtaLQ_Atlcuts.png" size="29054" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark jet pT distribution from MCFM, before any cuts" date="1176404620" name="lqjetpt.png" path="lqjetpt.png" size="23531" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution at LO, after Atlas-style cuts" date="1176475522" name="lord_tq_EtaLQ_cuts.png" path="lord_tq_EtaLQ_cuts.png" size="33273" user="Main.ReinhardSchwienhorst" version=""
Changed:
<
<
META FILEATTACHMENT attachment="mcfm_tq_EtaLQ_3j_nocuts.png" attr="h" comment="t-channel light quark eta distribution at NLO, but only for 3-jet events" date="1176495883" name="mcfm_tq_EtaLQ_3j_nocuts.png" path="mcfm_tq_EtaLQ_3j_nocuts.png" size="28454" stream="mcfm_tq_EtaLQ_3j_nocuts.png" user="Main.ReinhardSchwienhorst" version="0"
>
>
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution at NLO, but only for 3-jet events" date="1176495884" name="mcfm_tq_EtaLQ_3j_nocuts.png" path="mcfm_tq_EtaLQ_3j_nocuts.png" size="28454" user="Main.ReinhardSchwienhorst" version=""
 
META FILEATTACHMENT attr="h" autoattached="1" comment="Q*Eta distribution in t-channel single top at the Tevatron, from our MSU NLO study" date="1175887451" name="tevQEtaSmall.png" path="tevQEtaSmall.png" size="5236" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark jet pT distribution from MCFM, after Atlas-style cuts" date="1176404716" name="lqjetpt_aftercuts.png" path="lqjetpt_aftercuts.png" size="20738" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution at LO, before any cuts" date="1176475490" name="lord_tq_EtaLQ_nocuts.png" path="lord_tq_EtaLQ_nocuts.png" size="24476" user="Main.ReinhardSchwienhorst" version=""
Revision 35
Changes from r33 to r35
Line: 1 to 1
 
META TOPICPARENT name="NloStudies"

Studies of the light quark pseudorapidity distribution in t-channel single top

At the Tevatron, the t-channel single top quark signal has a very nice variable that can be exploited to separate the single top quark signal from the backgrounds. The light quark, also called spectator quark, that is scattered in the t-channel exchange of a W boson typically goes in the forward direction. The corresponding variable is called Q*Eta. In this variable, the pseudorapidity of the leading non-b-tagged jet is multiplied by Q, the charge of the lepton (i.e. the charge of the top quark). The distribution is peaked in the forward direction, at a pseudorapidity of about 1.5 to 2. The plot below shows this variable, this is from a study of Tevatron t-channel single top quark production
Line: 53 to 53
 
  • t-channel light quark eta distribution at NLO, but only for 2-jet events:
    mcfm_tq_EtaLQ_2j_nocuts.png
Added:
>
>
  • t-channel light quark eta distribution at NLO, but only for 3-jet events:
    mcfm_tq_EtaLQ_3j_nocuts.png
 
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution from MCFM, before any cuts" date="1175886282" name="mcfm_tq_EtaLQ_nocuts.png" path="mcfm_tq_EtaLQ_nocuts.png" size="28288" user="Main.ReinhardSchwienhorst" version=""
Added:
>
>
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution at NLO, but only for 2-jet events" date="1176494892" name="mcfm_tq_EtaLQ_2j_nocuts.png" path="mcfm_tq_EtaLQ_2j_nocuts.png" size="33148" user="Main.ReinhardSchwienhorst" version=""
 
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution from MCFM, after Atlas-style cuts" date="1175886537" name="mcfm_tq_EtaLQ_Atlcuts.png" path="mcfm_tq_EtaLQ_Atlcuts.png" size="29054" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark jet pT distribution from MCFM, before any cuts" date="1176404620" name="lqjetpt.png" path="lqjetpt.png" size="23531" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution at LO, after Atlas-style cuts" date="1176475522" name="lord_tq_EtaLQ_cuts.png" path="lord_tq_EtaLQ_cuts.png" size="33273" user="Main.ReinhardSchwienhorst" version=""
Added:
>
>
META FILEATTACHMENT attachment="mcfm_tq_EtaLQ_3j_nocuts.png" attr="h" comment="t-channel light quark eta distribution at NLO, but only for 3-jet events" date="1176495883" name="mcfm_tq_EtaLQ_3j_nocuts.png" path="mcfm_tq_EtaLQ_3j_nocuts.png" size="28454" stream="mcfm_tq_EtaLQ_3j_nocuts.png" user="Main.ReinhardSchwienhorst" version="0"
 
META FILEATTACHMENT attr="h" autoattached="1" comment="Q*Eta distribution in t-channel single top at the Tevatron, from our MSU NLO study" date="1175887451" name="tevQEtaSmall.png" path="tevQEtaSmall.png" size="5236" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark jet pT distribution from MCFM, after Atlas-style cuts" date="1176404716" name="lqjetpt_aftercuts.png" path="lqjetpt_aftercuts.png" size="20738" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution at LO, before any cuts" date="1176475490" name="lord_tq_EtaLQ_nocuts.png" path="lord_tq_EtaLQ_nocuts.png" size="24476" user="Main.ReinhardSchwienhorst" version=""
Deleted:
<
<
META FILEATTACHMENT attachment="mcfm_tq_EtaLQ_2j_nocuts.png" attr="h" comment="t-channel light quark eta distribution at NLO, but only for 2-jet events" date="1176494892" name="mcfm_tq_EtaLQ_2j_nocuts.png" path="mcfm_tq_EtaLQ_2j_nocuts.png" size="33148" stream="mcfm_tq_EtaLQ_2j_nocuts.png" user="Main.ReinhardSchwienhorst" version="0"
Revision 33
Changes from r31 to r33
Line: 1 to 1
 
META TOPICPARENT name="NloStudies"

Studies of the light quark pseudorapidity distribution in t-channel single top

At the Tevatron, the t-channel single top quark signal has a very nice variable that can be exploited to separate the single top quark signal from the backgrounds. The light quark, also called spectator quark, that is scattered in the t-channel exchange of a W boson typically goes in the forward direction. The corresponding variable is called Q*Eta. In this variable, the pseudorapidity of the leading non-b-tagged jet is multiplied by Q, the charge of the lepton (i.e. the charge of the top quark). The distribution is peaked in the forward direction, at a pseudorapidity of about 1.5 to 2. The plot below shows this variable, this is from a study of Tevatron t-channel single top quark production
Line: 36 to 36
  The distribution after cuts has changed and is peaked at the center (eta=0). The unique t-channel feature has disappeared. This is mostly the result of the jet pT cuts. With a looser cut of 20GeV on the pt of the jets, the distribution is more flat.
Deleted:
<
<
-- ReinhardSchwienhorst - 06 Apr 2007
 

Added:
>
>

Leading Order Distributions

The light quark jet pseudorapidity distribution looks very different if only the leading order term is included in the calculation. Below are the two relevant distributions:
  • t-channel light quark eta distribution at LO, before any cuts:
    lord_tq_EtaLQ_nocuts.png
  • t-channel light quark eta distribution at LO, after Atlas-style cuts:
    lord_tq_EtaLQ_cuts.png
 

Added:
>
>
-- ReinhardSchwienhorst - 06 Apr 2007 -- ReinhardSchwienhorst - 13 Apr 2007
 
Deleted:
<
<
  • t-channel light quark eta distribution at LO, before any cuts:
    lord_tq_EtaLQ_nocuts.png
 
Changed:
<
<
  • t-channel light quark eta distribution at LO, after Atlas-style cuts:
    lord_tq_EtaLQ_cuts.png
>
>
  • t-channel light quark eta distribution at NLO, but only for 2-jet events:
    mcfm_tq_EtaLQ_2j_nocuts.png
 

META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution from MCFM, before any cuts" date="1175886282" name="mcfm_tq_EtaLQ_nocuts.png" path="mcfm_tq_EtaLQ_nocuts.png" size="28288" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution from MCFM, after Atlas-style cuts" date="1175886537" name="mcfm_tq_EtaLQ_Atlcuts.png" path="mcfm_tq_EtaLQ_Atlcuts.png" size="29054" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark jet pT distribution from MCFM, before any cuts" date="1176404620" name="lqjetpt.png" path="lqjetpt.png" size="23531" user="Main.ReinhardSchwienhorst" version=""
Added:
>
>
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution at LO, after Atlas-style cuts" date="1176475522" name="lord_tq_EtaLQ_cuts.png" path="lord_tq_EtaLQ_cuts.png" size="33273" user="Main.ReinhardSchwienhorst" version=""
 
META FILEATTACHMENT attr="h" autoattached="1" comment="Q*Eta distribution in t-channel single top at the Tevatron, from our MSU NLO study" date="1175887451" name="tevQEtaSmall.png" path="tevQEtaSmall.png" size="5236" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark jet pT distribution from MCFM, after Atlas-style cuts" date="1176404716" name="lqjetpt_aftercuts.png" path="lqjetpt_aftercuts.png" size="20738" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution at LO, before any cuts" date="1176475490" name="lord_tq_EtaLQ_nocuts.png" path="lord_tq_EtaLQ_nocuts.png" size="24476" user="Main.ReinhardSchwienhorst" version=""
Changed:
<
<
META FILEATTACHMENT attachment="lord_tq_EtaLQ_cuts.png" attr="h" comment="t-channel light quark eta distribution at LO, after Atlas-style cuts" date="1176475521" name="lord_tq_EtaLQ_cuts.png" path="lord_tq_EtaLQ_cuts.png" size="33273" stream="lord_tq_EtaLQ_cuts.png" user="Main.ReinhardSchwienhorst" version="0"
>
>
META FILEATTACHMENT attachment="mcfm_tq_EtaLQ_2j_nocuts.png" attr="h" comment="t-channel light quark eta distribution at NLO, but only for 2-jet events" date="1176494892" name="mcfm_tq_EtaLQ_2j_nocuts.png" path="mcfm_tq_EtaLQ_2j_nocuts.png" size="33148" stream="mcfm_tq_EtaLQ_2j_nocuts.png" user="Main.ReinhardSchwienhorst" version="0"
Revision 31
Changes from r29 to r31
Line: 1 to 1
 
META TOPICPARENT name="NloStudies"

Studies of the light quark pseudorapidity distribution in t-channel single top

At the Tevatron, the t-channel single top quark signal has a very nice variable that can be exploited to separate the single top quark signal from the backgrounds. The light quark, also called spectator quark, that is scattered in the t-channel exchange of a W boson typically goes in the forward direction. The corresponding variable is called Q*Eta. In this variable, the pseudorapidity of the leading non-b-tagged jet is multiplied by Q, the charge of the lepton (i.e. the charge of the top quark). The distribution is peaked in the forward direction, at a pseudorapidity of about 1.5 to 2. The plot below shows this variable, this is from a study of Tevatron t-channel single top quark production
Line: 42 to 42
 

Added:
>
>
  • t-channel light quark eta distribution at LO, before any cuts:
    lord_tq_EtaLQ_nocuts.png

  • t-channel light quark eta distribution at LO, after Atlas-style cuts:
    lord_tq_EtaLQ_cuts.png
 
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution from MCFM, before any cuts" date="1175886282" name="mcfm_tq_EtaLQ_nocuts.png" path="mcfm_tq_EtaLQ_nocuts.png" size="28288" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution from MCFM, after Atlas-style cuts" date="1175886537" name="mcfm_tq_EtaLQ_Atlcuts.png" path="mcfm_tq_EtaLQ_Atlcuts.png" size="29054" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark jet pT distribution from MCFM, before any cuts" date="1176404620" name="lqjetpt.png" path="lqjetpt.png" size="23531" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="Q*Eta distribution in t-channel single top at the Tevatron, from our MSU NLO study" date="1175887451" name="tevQEtaSmall.png" path="tevQEtaSmall.png" size="5236" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark jet pT distribution from MCFM, after Atlas-style cuts" date="1176404716" name="lqjetpt_aftercuts.png" path="lqjetpt_aftercuts.png" size="20738" user="Main.ReinhardSchwienhorst" version=""
Added:
>
>
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution at LO, before any cuts" date="1176475490" name="lord_tq_EtaLQ_nocuts.png" path="lord_tq_EtaLQ_nocuts.png" size="24476" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attachment="lord_tq_EtaLQ_cuts.png" attr="h" comment="t-channel light quark eta distribution at LO, after Atlas-style cuts" date="1176475521" name="lord_tq_EtaLQ_cuts.png" path="lord_tq_EtaLQ_cuts.png" size="33273" stream="lord_tq_EtaLQ_cuts.png" user="Main.ReinhardSchwienhorst" version="0"
Revision 29
Changes from r27 to r29
Line: 1 to 1
 
META TOPICPARENT name="NloStudies"

Studies of the light quark pseudorapidity distribution in t-channel single top

At the Tevatron, the t-channel single top quark signal has a very nice variable that can be exploited to separate the single top quark signal from the backgrounds. The light quark, also called spectator quark, that is scattered in the t-channel exchange of a W boson typically goes in the forward direction. The corresponding variable is called Q*Eta. In this variable, the pseudorapidity of the leading non-b-tagged jet is multiplied by Q, the charge of the lepton (i.e. the charge of the top quark). The distribution is peaked in the forward direction, at a pseudorapidity of about 1.5 to 2. The plot below shows this variable, this is from a study of Tevatron t-channel single top quark production
Line: 16 to 16
 

MCFM output, no cuts

  • t-channel light quark eta distribution from MCFM, before any cuts:
    mcfm_tq_EtaLQ_nocuts.png
Added:
>
>
* t-channel light quark jet pT distribution from MCFM, before any cuts:
lqjetpt.png
 

There is no clear peak at high pseudorapidities. The distribution is rather wide and almost flat out to an eta of about 2. For higher pseudorapidities it drops off quickly.
Line: 25 to 27
 
  • MET>20GeV
  • At least two jets with jet pT>30GeV
Changed:
<
<
The result is the following t-channel light quark eta distribution:
>
>
The result is the following:
  • t-channel light quark eta distribution:
  mcfm_tq_EtaLQ_Atlcuts.png
Added:
>
>
  • t-channel light quark jet pT distribution from MCFM, after Atlas-style cuts:
    lqjetpt_aftercuts.png
 

The distribution after cuts has changed and is peaked at the center (eta=0). The unique t-channel feature has disappeared. This is mostly the result of the jet pT cuts. With a looser cut of 20GeV on the pt of the jets, the distribution is more flat.
Line: 35 to 40
 

Changed:
<
<
  • t-channel light quark jet pT distribution from MCFM, before any cuts:
    lqjetpt.png
>
>

 

META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution from MCFM, before any cuts" date="1175886282" name="mcfm_tq_EtaLQ_nocuts.png" path="mcfm_tq_EtaLQ_nocuts.png" size="28288" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution from MCFM, after Atlas-style cuts" date="1175886537" name="mcfm_tq_EtaLQ_Atlcuts.png" path="mcfm_tq_EtaLQ_Atlcuts.png" size="29054" user="Main.ReinhardSchwienhorst" version=""
Added:
>
>
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark jet pT distribution from MCFM, before any cuts" date="1176404620" name="lqjetpt.png" path="lqjetpt.png" size="23531" user="Main.ReinhardSchwienhorst" version=""
 
META FILEATTACHMENT attr="h" autoattached="1" comment="Q*Eta distribution in t-channel single top at the Tevatron, from our MSU NLO study" date="1175887451" name="tevQEtaSmall.png" path="tevQEtaSmall.png" size="5236" user="Main.ReinhardSchwienhorst" version=""
Changed:
<
<
META FILEATTACHMENT attachment="lqjetpt.png" attr="h" comment="t-channel light quark jet pT distribution from MCFM, before any cuts" date="1176404619" name="lqjetpt.png" path="lqjetpt.png" size="23531" stream="lqjetpt.png" user="Main.ReinhardSchwienhorst" version="0"
>
>
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark jet pT distribution from MCFM, after Atlas-style cuts" date="1176404716" name="lqjetpt_aftercuts.png" path="lqjetpt_aftercuts.png" size="20738" user="Main.ReinhardSchwienhorst" version=""
Revision 27
Changes from r25 to r27
Line: 1 to 1
 
META TOPICPARENT name="NloStudies"

Studies of the light quark pseudorapidity distribution in t-channel single top

At the Tevatron, the t-channel single top quark signal has a very nice variable that can be exploited to separate the single top quark signal from the backgrounds. The light quark, also called spectator quark, that is scattered in the t-channel exchange of a W boson typically goes in the forward direction. The corresponding variable is called Q*Eta. In this variable, the pseudorapidity of the leading non-b-tagged jet is multiplied by Q, the charge of the lepton (i.e. the charge of the top quark). The distribution is peaked in the forward direction, at a pseudorapidity of about 1.5 to 2. The plot below shows this variable, this is from a study of Tevatron t-channel single top quark production
Line: 35 to 35
 

Added:
>
>
  • t-channel light quark jet pT distribution from MCFM, before any cuts:
    lqjetpt.png
 
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution from MCFM, before any cuts" date="1175886282" name="mcfm_tq_EtaLQ_nocuts.png" path="mcfm_tq_EtaLQ_nocuts.png" size="28288" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution from MCFM, after Atlas-style cuts" date="1175886537" name="mcfm_tq_EtaLQ_Atlcuts.png" path="mcfm_tq_EtaLQ_Atlcuts.png" size="29054" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="Q*Eta distribution in t-channel single top at the Tevatron, from our MSU NLO study" date="1175887451" name="tevQEtaSmall.png" path="tevQEtaSmall.png" size="5236" user="Main.ReinhardSchwienhorst" version=""
Added:
>
>
META FILEATTACHMENT attachment="lqjetpt.png" attr="h" comment="t-channel light quark jet pT distribution from MCFM, before any cuts" date="1176404619" name="lqjetpt.png" path="lqjetpt.png" size="23531" stream="lqjetpt.png" user="Main.ReinhardSchwienhorst" version="0"
Revision 25
Changes from r23 to r25
Line: 1 to 1
 
META TOPICPARENT name="NloStudies"

Studies of the light quark pseudorapidity distribution in t-channel single top

At the Tevatron, the t-channel single top quark signal has a very nice variable that can be exploited to separate the single top quark signal from the backgrounds. The light quark, also called spectator quark, that is scattered in the t-channel exchange of a W boson typically goes in the forward direction. The corresponding variable is called Q*Eta. In this variable, the pseudorapidity of the leading non-b-tagged jet is multiplied by Q, the charge of the lepton (i.e. the charge of the top quark). The distribution is peaked in the forward direction, at a pseudorapidity of about 1.5 to 2. The plot below shows this variable, this is from a study of Tevatron t-channel single top quark production
Line: 11 to 11
  At the LHC the situation is different. First, the initial beam is proton-proton rather than proton-antiproton. Thus, every distribution is symmetric in eta, and selecting events by charge of the lepton doesn't make any difference. Second, the initial beam energy is much higher, and top quarks are produced farther away from threshold and hence experience the top quark and the light quark jet will be more central.
Changed:
<
<
Here we show the results of a quick study using MCFM. In this study, the top quark mass was set to 175GeV, and the same value was chosen for factorization and renormalization scales. The CTEQ6M PDF set was chosen.
>
>
Here we show the results of a quick study using MCFM. In this study, the top quark mass was set to 175GeV, and the same value was chosen for factorization and renormalization scales. The CTEQ6M PDF set was chosen. Both top and antitop quark production is included. With these settings, the total cross section at NLO for top quark production only is 150pb, and that for antitop production is 109pb. Note that MCFM uses massless b-quarks for s-channel and t-channel single top.
 

MCFM output, no cuts

  • t-channel light quark eta distribution from MCFM, before any cuts:
Revision 23
Changes from r21 to r23
Line: 1 to 1
 
META TOPICPARENT name="NloStudies"

Studies of the light quark pseudorapidity distribution in t-channel single top

At the Tevatron, the t-channel single top quark signal has a very nice variable that can be exploited to separate the single top quark signal from the backgrounds. The light quark, also called spectator quark, that is scattered in the t-channel exchange of a W boson typically goes in the forward direction. The corresponding variable is called Q*Eta. In this variable, the pseudorapidity of the leading non-b-tagged jet is multiplied by Q, the charge of the lepton (i.e. the charge of the top quark). The distribution is peaked in the forward direction, at a pseudorapidity of about 1.5 to 2. The plot below shows this variable, this is from a study of Tevatron t-channel single top quark production
Line: 7 to 7
  tevQEtaSmall.png
Added:
>
>

MCFM, LHC, Atlas

  At the LHC the situation is different. First, the initial beam is proton-proton rather than proton-antiproton. Thus, every distribution is symmetric in eta, and selecting events by charge of the lepton doesn't make any difference.
Changed:
<
<
Second, the initial beam energy is much higher, and top quarks are not produced so much at threshold and hence every eta distribution is a little wider.
>
>
Second, the initial beam energy is much higher, and top quarks are produced farther away from threshold and hence experience the top quark and the light quark jet will be more central.
 

Here we show the results of a quick study using MCFM. In this study, the top quark mass was set to 175GeV, and the same value was chosen for factorization and renormalization scales. The CTEQ6M PDF set was chosen.
Line: 20 to 21
  There is no clear peak at high pseudorapidities. The distribution is rather wide and almost flat out to an eta of about 2. For higher pseudorapidities it drops off quickly.

MCFM output, with Atlas-style cuts

Changed:
<
<
The following cuts were made to obtain this distribution:
>
>
The following cuts were made to mirror what has been used in recent Atlas analyses:
 
  • lepton pT>20GeV
  • MET>20GeV
  • At least two jets with jet pT>30GeV
Revision 21
Changes from r19 to r21
Line: 1 to 1
 
META TOPICPARENT name="NloStudies"

Studies of the light quark pseudorapidity distribution in t-channel single top

Changed:
<
<
At the Tevatron, the t-channel single top quark signal has a very nice variable that can be exploited to separate the single top quark signal from the backgrounds. The light quark, also called spectator quark, that is scattered in the t-channel exchange of a W boson typically goes in the forward direction. The corresponding variable is called QTimesEta. In this variable, the pseudorapidity of the leading non-b-tagged jet is multiplied by Q, the charge of the lepton (i.e. the charge of the top quark). The distribution is peaked in the forward direction, at a pseudorapidity of about 1.5 to 2.
>
>
At the Tevatron, the t-channel single top quark signal has a very nice variable that can be exploited to separate the single top quark signal from the backgrounds. The light quark, also called spectator quark, that is scattered in the t-channel exchange of a W boson typically goes in the forward direction. The corresponding variable is called Q*Eta. In this variable, the pseudorapidity of the leading non-b-tagged jet is multiplied by Q, the charge of the lepton (i.e. the charge of the top quark). The distribution is peaked in the forward direction, at a pseudorapidity of about 1.5 to 2. The plot below shows this variable, this is from a study of Tevatron t-channel single top quark production at NLO done by us at MSU (PRD72,094027 (2005)). tevQEtaSmall.png
 
Deleted:
<
<
| This is the QTimesEta distributionfrom the NLO study done by us at MSU (NLO t-channel study). | tevQEtaSmall.png |

this is my table
 

At the LHC the situation is different. First, the initial beam is proton-proton rather than proton-antiproton. Thus, every distribution is symmetric in eta, and selecting events by charge of the lepton doesn't make any difference. Second, the initial beam energy is much higher, and top quarks are not produced so much at threshold and hence every eta distribution is a little wider.
Revision 19
Changes from r17 to r19
Line: 1 to 1
 
META TOPICPARENT name="NloStudies"

Studies of the light quark pseudorapidity distribution in t-channel single top

At the Tevatron, the t-channel single top quark signal has a very nice variable that can be exploited to separate the single top quark signal from the backgrounds. The light quark, also called spectator quark, that is scattered in the t-channel exchange of a W boson typically goes in the forward direction. The corresponding variable is called QTimesEta. In this variable, the pseudorapidity of the leading non-b-tagged jet is multiplied by Q, the charge of the lepton (i.e. the charge of the top quark). The distribution is peaked in the forward direction, at a pseudorapidity of about 1.5 to 2.
Line: 8 to 8
  (NLO t-channel study). | tevQEtaSmall.png |
Changed:
<
<
>
>
 
this is my table

At the LHC the situation is different. First, the initial beam is proton-proton rather than proton-antiproton. Thus, every distribution is symmetric in eta, and selecting events by charge of the lepton doesn't make any difference.
Revision 17
Changes from r15 to r17
Line: 1 to 1
 
META TOPICPARENT name="NloStudies"

Studies of the light quark pseudorapidity distribution in t-channel single top

At the Tevatron, the t-channel single top quark signal has a very nice variable that can be exploited to separate the single top quark signal from the backgrounds. The light quark, also called spectator quark, that is scattered in the t-channel exchange of a W boson typically goes in the forward direction. The corresponding variable is called QTimesEta. In this variable, the pseudorapidity of the leading non-b-tagged jet is multiplied by Q, the charge of the lepton (i.e. the charge of the top quark). The distribution is peaked in the forward direction, at a pseudorapidity of about 1.5 to 2.
Line: 8 to 8
  (NLO t-channel study). | tevQEtaSmall.png |
Changed:
<
<

>
>
 
this is my table

At the LHC the situation is different. First, the initial beam is proton-proton rather than proton-antiproton. Thus, every distribution is symmetric in eta, and selecting events by charge of the lepton doesn't make any difference.
Revision 15
Changes from r13 to r15
Line: 1 to 1
 
META TOPICPARENT name="NloStudies"

Studies of the light quark pseudorapidity distribution in t-channel single top

At the Tevatron, the t-channel single top quark signal has a very nice variable that can be exploited to separate the single top quark signal from the backgrounds. The light quark, also called spectator quark, that is scattered in the t-channel exchange of a W boson typically goes in the forward direction. The corresponding variable is called QTimesEta. In this variable, the pseudorapidity of the leading non-b-tagged jet is multiplied by Q, the charge of the lepton (i.e. the charge of the top quark). The distribution is peaked in the forward direction, at a pseudorapidity of about 1.5 to 2.
Line: 9 to 9
 
tevQEtaSmall.png

Added:
>
>
this is my table
 

At the LHC the situation is different. First, the initial beam is proton-proton rather than proton-antiproton. Thus, every distribution is symmetric in eta, and selecting events by charge of the lepton doesn't make any difference. Second, the initial beam energy is much higher, and top quarks are not produced so much at threshold and hence every eta distribution is a little wider.
Revision 13
Changes from r11 to r13
Line: 1 to 1
 
META TOPICPARENT name="NloStudies"

Studies of the light quark pseudorapidity distribution in t-channel single top

At the Tevatron, the t-channel single top quark signal has a very nice variable that can be exploited to separate the single top quark signal from the backgrounds. The light quark, also called spectator quark, that is scattered in the t-channel exchange of a W boson typically goes in the forward direction. The corresponding variable is called QTimesEta. In this variable, the pseudorapidity of the leading non-b-tagged jet is multiplied by Q, the charge of the lepton (i.e. the charge of the top quark). The distribution is peaked in the forward direction, at a pseudorapidity of about 1.5 to 2.
Line: 6 to 7
  from the NLO study done by us at MSU (NLO t-channel study).|tevQEtaSmall.png|
Deleted:
<
<
This QTimesEta distribution is here
 

Deleted:
<
<
This distribution of this quark jet at NLO is
 

At the LHC the situation is different. First, the initial beam is proton-proton rather than proton-antiproton. Thus, every distribution is symmetric in eta, and selecting events by charge of the lepton doesn't make any difference. Second, the initial beam energy is much higher, and top quarks are not produced so much at threshold and hence every eta distribution is a little wider.
Revision 11
Changes from r9 to r11
Line: 1 to 1
 
META TOPICPARENT name="NloStudies"

Studies of the light quark pseudorapidity distribution in t-channel single top

At the Tevatron, the t-channel single top quark signal has a very nice variable that can be exploited to separate the single top quark signal from the backgrounds. The light quark, also called spectator quark, that is scattered in the t-channel exchange of a W boson typically goes in the forward direction. The corresponding variable is called QTimesEta. In this variable, the pseudorapidity of the leading non-b-tagged jet is multiplied by Q, the charge of the lepton (i.e. the charge of the top quark). The distribution is peaked in the forward direction, at a pseudorapidity of about 1.5 to 2.
Changed:
<
<
This distribution of this quark jet at NLO is this NLO t-channel study.
>
>
|This is the QTimesEta distributionfrom the NLO study done by us at MSU (NLO t-channel study).|tevQEtaSmall.png| This QTimesEta distribution is here

This distribution of this quark jet at NLO is
 

At the LHC the situation is different. First, the initial beam is proton-proton rather than proton-antiproton. Thus, every distribution is symmetric in eta, and selecting events by charge of the lepton doesn't make any difference. Second, the initial beam energy is much higher, and top quarks are not produced so much at threshold and hence every eta distribution is a little wider.
Line: 34 to 41
 

META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution from MCFM, before any cuts" date="1175886282" name="mcfm_tq_EtaLQ_nocuts.png" path="mcfm_tq_EtaLQ_nocuts.png" size="28288" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution from MCFM, after Atlas-style cuts" date="1175886537" name="mcfm_tq_EtaLQ_Atlcuts.png" path="mcfm_tq_EtaLQ_Atlcuts.png" size="29054" user="Main.ReinhardSchwienhorst" version=""
Changed:
<
<
META FILEATTACHMENT attachment="tevQEtaSmall.png" attr="" comment="Q*Eta distribution in t-channel single top at the Tevatron, from our MSU NLO study" date="1175887451" name="tevQEtaSmall.png" path="tevQEtaSmall.png" size="5236" stream="tevQEtaSmall.png" user="Main.ReinhardSchwienhorst" version="0"
>
>
META FILEATTACHMENT attr="h" autoattached="1" comment="Q*Eta distribution in t-channel single top at the Tevatron, from our MSU NLO study" date="1175887451" name="tevQEtaSmall.png" path="tevQEtaSmall.png" size="5236" user="Main.ReinhardSchwienhorst" version=""
Revision 9
Changes from r7 to r9
Line: 1 to 1
 
META TOPICPARENT name="NloStudies"

Studies of the light quark pseudorapidity distribution in t-channel single top

Changed:
<
<
At the Tevatron, the t-channel single top quark signal has a very nice variable that can be exploited to separate the single top quark signal from the backgrounds. The light quark, also called spectator quark, that is scattered in the t-channel exchange of a W boson typically goes in the forward direction. This variable is called QTimesEta. In this variable, the pseudorapidity of the leading non-b-tagged jet is multiplied by Q, the charge of the lepton (i.e. the charge of the top quark). The distribution is peaked in the forward direction, at a pseudorapidity of about 1.5 to 2. This distribution of this quark jet at NLO can be seen for example in this NLO t-channel study.
>
>
At the Tevatron, the t-channel single top quark signal has a very nice variable that can be exploited to separate the single top quark signal from the backgrounds. The light quark, also called spectator quark, that is scattered in the t-channel exchange of a W boson typically goes in the forward direction. The corresponding variable is called QTimesEta. In this variable, the pseudorapidity of the leading non-b-tagged jet is multiplied by Q, the charge of the lepton (i.e. the charge of the top quark). The distribution is peaked in the forward direction, at a pseudorapidity of about 1.5 to 2. This distribution of this quark jet at NLO is this NLO t-channel study.
 

At the LHC the situation is different. First, the initial beam is proton-proton rather than proton-antiproton. Thus, every distribution is symmetric in eta, and selecting events by charge of the lepton doesn't make any difference. Second, the initial beam energy is much higher, and top quarks are not produced so much at threshold and hence every eta distribution is a little wider.
Changed:
<
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Here we show the results of a quick study using MCFM.
>
>
Here we show the results of a quick study using MCFM. In this study, the top quark mass was set to 175GeV, and the same value was chosen for factorization and renormalization scales. The CTEQ6M PDF set was chosen.
 

MCFM output, no cuts

  • t-channel light quark eta distribution from MCFM, before any cuts:
    mcfm_tq_EtaLQ_nocuts.png
Changed:
<
<
>
>
There is no clear peak at high pseudorapidities. The distribution is rather wide and almost flat out to an eta of about 2. For higher pseudorapidities it drops off quickly.
 

MCFM output, with Atlas-style cuts

The following cuts were made to obtain this distribution:
  • lepton pT>20GeV
  • MET>20GeV
Changed:
<
<
  • jet pT>30GeV
>
>
  • At least two jets with jet pT>30GeV
 

The result is the following t-channel light quark eta distribution:
mcfm_tq_EtaLQ_Atlcuts.png
Added:
>
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The distribution after cuts has changed and is peaked at the center (eta=0). The unique t-channel feature has disappeared. This is mostly the result of the jet pT cuts. With a looser cut of 20GeV on the pt of the jets, the distribution is more flat.
 

-- ReinhardSchwienhorst - 06 Apr 2007
Line: 31 to 34
 

META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution from MCFM, before any cuts" date="1175886282" name="mcfm_tq_EtaLQ_nocuts.png" path="mcfm_tq_EtaLQ_nocuts.png" size="28288" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution from MCFM, after Atlas-style cuts" date="1175886537" name="mcfm_tq_EtaLQ_Atlcuts.png" path="mcfm_tq_EtaLQ_Atlcuts.png" size="29054" user="Main.ReinhardSchwienhorst" version=""
Added:
>
>
META FILEATTACHMENT attachment="tevQEtaSmall.png" attr="" comment="Q*Eta distribution in t-channel single top at the Tevatron, from our MSU NLO study" date="1175887451" name="tevQEtaSmall.png" path="tevQEtaSmall.png" size="5236" stream="tevQEtaSmall.png" user="Main.ReinhardSchwienhorst" version="0"
Revision 7
Changes from r5 to r7
Line: 1 to 1
 
META TOPICPARENT name="NloStudies"

Studies of the light quark pseudorapidity distribution in t-channel single top

At the Tevatron, the t-channel single top quark signal has a very nice variable that can be exploited to separate the single top quark signal from the backgrounds. The light quark, also called spectator quark, that is scattered in the t-channel exchange of a W boson typically goes in the forward direction. This variable is called QTimesEta. In this variable, the pseudorapidity of the leading non-b-tagged jet is multiplied by Q, the charge of the lepton (i.e. the charge of the top quark). The distribution is peaked in the forward direction, at a pseudorapidity of about 1.5 to 2.
Line: 16 to 16
 

MCFM output, with Atlas-style cuts

Added:
>
>
The following cuts were made to obtain this distribution:
  • lepton pT>20GeV
  • MET>20GeV
  • jet pT>30GeV

The result is the following t-channel light quark eta distribution:
mcfm_tq_EtaLQ_Atlcuts.png
 

-- ReinhardSchwienhorst - 06 Apr 2007
Deleted:
<
<
  • t-channel light quark eta distribution from MCFM, after Atlas-style cuts:
    mcfm_tq_EtaLQ_Atlcuts.png
 
Changed:
<
<
META FILEATTACHMENT attachment="mcfm_tq_EtaLQ_nocuts.png" attr="h" comment="t-channel light quark eta distribution from MCFM, before any cuts" date="1175886282" name="mcfm_tq_EtaLQ_nocuts.png" path="mcfm_tq_EtaLQ_nocuts.png" size="28288" stream="mcfm_tq_EtaLQ_nocuts.png" user="Main.ReinhardSchwienhorst" version="0"
META FILEATTACHMENT attachment="mcfm_tq_EtaLQ_Atlcuts.png" attr="h" comment="t-channel light quark eta distribution from MCFM, after Atlas-style cuts" date="1175886537" name="mcfm_tq_EtaLQ_Atlcuts.png" path="mcfm_tq_EtaLQ_Atlcuts.png" size="29054" stream="mcfm_tq_EtaLQ_Atlcuts.png" user="Main.ReinhardSchwienhorst" version="0"
>
>

META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution from MCFM, before any cuts" date="1175886282" name="mcfm_tq_EtaLQ_nocuts.png" path="mcfm_tq_EtaLQ_nocuts.png" size="28288" user="Main.ReinhardSchwienhorst" version=""
META FILEATTACHMENT attr="h" autoattached="1" comment="t-channel light quark eta distribution from MCFM, after Atlas-style cuts" date="1175886537" name="mcfm_tq_EtaLQ_Atlcuts.png" path="mcfm_tq_EtaLQ_Atlcuts.png" size="29054" user="Main.ReinhardSchwienhorst" version=""
Revision 5
Changes from r3 to r5
Line: 1 to 1
 
META TOPICPARENT name="NloStudies"

Studies of the light quark pseudorapidity distribution in t-channel single top

At the Tevatron, the t-channel single top quark signal has a very nice variable that can be exploited to separate the single top quark signal from the backgrounds. The light quark, also called spectator quark, that is scattered in the t-channel exchange of a W boson typically goes in the forward direction. This variable is called QTimesEta. In this variable, the pseudorapidity of the leading non-b-tagged jet is multiplied by Q, the charge of the lepton (i.e. the charge of the top quark). The distribution is peaked in the forward direction, at a pseudorapidity of about 1.5 to 2.
Line: 7 to 7
  At the LHC the situation is different. First, the initial beam is proton-proton rather than proton-antiproton. Thus, every distribution is symmetric in eta, and selecting events by charge of the lepton doesn't make any difference. Second, the initial beam energy is much higher, and top quarks are not produced so much at threshold and hence every eta distribution is a little wider.
Changed:
<
<
-- ReinhardSchwienhorst - 06 Apr 2007
>
>
Here we show the results of a quick study using MCFM.

MCFM output, no cuts

 
  • t-channel light quark eta distribution from MCFM, before any cuts:
Changed:
<
<
mcfm_tq_EtaLQ_nocuts.png
>
>
mcfm_tq_EtaLQ_nocuts.png

MCFM output, with Atlas-style cuts

-- ReinhardSchwienhorst - 06 Apr 2007

  • t-channel light quark eta distribution from MCFM, after Atlas-style cuts:
    mcfm_tq_EtaLQ_Atlcuts.png
 

META FILEATTACHMENT attachment="mcfm_tq_EtaLQ_nocuts.png" attr="h" comment="t-channel light quark eta distribution from MCFM, before any cuts" date="1175886282" name="mcfm_tq_EtaLQ_nocuts.png" path="mcfm_tq_EtaLQ_nocuts.png" size="28288" stream="mcfm_tq_EtaLQ_nocuts.png" user="Main.ReinhardSchwienhorst" version="0"
Added:
>
>
META FILEATTACHMENT attachment="mcfm_tq_EtaLQ_Atlcuts.png" attr="h" comment="t-channel light quark eta distribution from MCFM, after Atlas-style cuts" date="1175886537" name="mcfm_tq_EtaLQ_Atlcuts.png" path="mcfm_tq_EtaLQ_Atlcuts.png" size="29054" stream="mcfm_tq_EtaLQ_Atlcuts.png" user="Main.ReinhardSchwienhorst" version="0"
Revision 3
Changes from r1 to r3
Line: 1 to 1
 
META TOPICPARENT name="NloStudies"

Studies of the light quark pseudorapidity distribution in t-channel single top

Added:
>
>
At the Tevatron, the t-channel single top quark signal has a very nice variable that can be exploited to separate the single top quark signal from the backgrounds. The light quark, also called spectator quark, that is scattered in the t-channel exchange of a W boson typically goes in the forward direction. This variable is called QTimesEta. In this variable, the pseudorapidity of the leading non-b-tagged jet is multiplied by Q, the charge of the lepton (i.e. the charge of the top quark). The distribution is peaked in the forward direction, at a pseudorapidity of about 1.5 to 2. This distribution of this quark jet at NLO can be seen for example in this NLO t-channel study.
 
Changed:
<
<
>
>
At the LHC the situation is different. First, the initial beam is proton-proton rather than proton-antiproton. Thus, every distribution is symmetric in eta, and selecting events by charge of the lepton doesn't make any difference. Second, the initial beam energy is much higher, and top quarks are not produced so much at threshold and hence every eta distribution is a little wider.
 

-- ReinhardSchwienhorst - 06 Apr 2007 \ No newline at end of file
Added:
>
>
  • t-channel light quark eta distribution from MCFM, before any cuts:
    mcfm_tq_EtaLQ_nocuts.png

META FILEATTACHMENT attachment="mcfm_tq_EtaLQ_nocuts.png" attr="h" comment="t-channel light quark eta distribution from MCFM, before any cuts" date="1175886282" name="mcfm_tq_EtaLQ_nocuts.png" path="mcfm_tq_EtaLQ_nocuts.png" size="28288" stream="mcfm_tq_EtaLQ_nocuts.png" user="Main.ReinhardSchwienhorst" version="0"
 
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