# Presentation: 325723

## Analysis of CP Violating Higgs in MSSM using the process 

-                    t->bH+, H+->WH1, H1->bb
-                    (Generetor level analysis)

- Arun Nayak    (TIFR)

- Les Houches meeting

- June 07

## (LEP Higgs working group, hep-ex/0602042)

- LEP limits  for CPX scenario :
- Because of the suppressed H1ZZ coupling, LEP can not exclude the presence of
- a light Higgs boson at low tan (~ 3.5 to 10)

- Les Houches meeting

- June 07

## Higgs Production in CPX scenario :

- Phenomenological analysis by Ghosh, Godbole, Roy  hep-ph/0412193
- Because of the suppressed H1VV coupling one of the pseudo-scalar Higgs state is very light
- Since there is correlation between the mass of charged Higgs and that of the pseudo-scalar
- Higgs state in MSSM, that implies a light charged Higgs, with MH+< Mt .
- A suppressed H1VV coupling implies increase in H1H+W coupling because of the sum rule
-                                             g2HiVV + | gHiH+W- |2 = 1
- And that implies an increase in branching ratio of H+->H1W ( > 47% over the entire range)
- The traditional decay mode H+->  is suppressed over an order of magnitude.
- Hence both light H1 & H+ can be probed using
- this process
- pp -> t               +                     t~   + X
-                                                
-          bH+                                                  b~W
-                                                      
-              W            H1                                  qq~(l)
-                            
-               l(qq~)     bb~

- (hep-ph/0412193)

- Les Houches meeting

- June 07

## Slide 4

- Les Houches meeting

- June 07

## Slide 5

- Les Houches meeting

- June 07

## Slide 6

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- June 07

## Slide 7

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- June 07

## Top & W mass reconstruction :

- The plots shows the reconstructed W mass for W->jj,
- and top mass for t->bl & t->bjj
- The combinations with inv. mass close to W or top
- mass has been considered.
- For t->bjj case, a mass window for jj inv. mass
- has been applied. 65 GeV < mjj < 95 GeV

- Les Houches meeting

- June 07

##                        Full simulation 

- Jets using Iterative cone algorthim with cone size 0.5 (, )

- Les Houches meeting

- June 07

## Top mass contd.... 

- Top mass contd....
- Distribution of top mass for t->bbbl & t->bbbjj , the combination with inv. mass close to
- top mass was considered. For t->bbbjj case, a mass window on jj inv. mass was applied.
- 65 GeV < mjj < 95 GeV

- Les Houches meeting

- June 07

## Plots for 30 fb-1 data

- H1 & H+ mass reconstruction :
- Reconstructed mass of H1(2 b jets) & H+(2 b jets and W).  Plot includes both signal and
- background events. All combinatorial backgrounds are also included in 2 b-jet (H1) inv. mass
- Two b-jets with inv. mass close to peak of H1 mass distribution and lies within 15 GeV around
- the peak  were considered for H+ reconstruction.

- Les Houches meeting

- June 07

##          pT difference of b-jets 

- 2 lowest pT b-jets

-          pT difference of b-jets

- Les Houches meeting

- June 07

## ttjj background analysis :

- selection :
-    selection of events similar to the signal events, one W-> lnu and
-    other W->2 jets.
-    Here the final state consists two b-jets from two top quark, atleast
-    4 light quark jets, one charged lepton.
-    One W reconstructed from charged lepton and mising Et with W mass
-    constraint.  Other W from two light jets( making all possible
-    combination), W mass window 65 to 95 GeV.
-    One top reconstructed from one of two b jets and one of two (or three) W.
-    Out of remaining light jets, two jets are selected as b-jets (to do a fake
-     mis tagging)
-    Assuming a maximum possiblity, two light jets which in combination with
-    remaining one b and remaining one W gives the best top mass
-    (within  175 ± 25 GeV),  has been used as two b-jets. |(two selected jets)<2.5
-     Since I put a mass window on bbbW, I select 2-fake b-jets in this way.
-     other light jets, if taken (mis tagged) as b-jets, will not survive in the selection
-     cuts. This way of choosing two fake b-jets maximise the possible background
-     from ttjj events.

- Les Houches meeting

- June 07

## Now there are 4 b-jets (including two fake b-jets), so one can  reconstruct 

- two top and H1 and H+ using the same procedure as signal events
- with same  mass window for top, W  and H1.
- Since two fake b-jets has been considered, we multiply a constant
- (corresponding to mistagging rate) to the final selected events.
- Assuming that mistagging rate per jet is 1%,  for two jets to be
- mistagged, a constant 0.01*0.01 = 0.0001 is multiplied  to
- final selected ttjj events.
- We assume a 50% b-tagging efficiency per jet. So we multiply a factor of 0.0625
- (efficiency for tagging 4 b-jets) to signal and ttbb events and 0.25(efficiency
- for tagging 2 b-jets) to ttjj events.
-  Cross section of events after final selections : (i.e. no. of events in H+ mass
-  distribution plots)
-        signal :      ~ 1.063 fb
-        ttbb bkg :  ~  0.051 fb
-        ttjj bkg   :  ~  0.0296 fb

- Les Houches meeting

- June 07

## Signal & background contribution :

- The major background to 2 b-jet invariant mass comes from the combinatorial backgrounds
- which may make the distribution very wide and have long tail.  But a clear peak on top of it
- helps to  chose the correct b-jet pair for the H+ reconstruction.

- Plots for 30 fb-1 data

- Les Houches meeting

- June 07

##              Selection details

|  | Cross section
 pb
(no. of events) | Wl
Wqq | |(b)|
< 2.5
PT(b)>  20GeV | Atleast 6 jets | 4 b-jets matched to b-quarks | Reco
W(l+MET)
&
W(2 jets)
65<mjj<95 | Top
(b-jet +W)
150<mt<200 | Top
(3 b-jets + W)
150<mt<200 | H1
(2 b-jets)
35<mh1<65 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| signal | 8.675
(260000) | 76100 | 17803 | 14265 | 6579 | 2634 | 2529 | 515 | 510
1.063 fb |
| ttbb | 3.285
(100000) | 29037 | 15563 | 13124 | 6672 | 2242 | 2212 | 27 | 25
0.051 fb |
| ttjj | 506.99
(2000000) | 564403 | 458889 | 389639 | 340402
(2 b-jets only) | 166713 | 152193 | 5109 | 4675
0.0296 fb |

- **  multiply b-tag efficiency factor to final selected events to get the final state cross section

- Les Houches meeting

- June 07

##    Simultaneous Top Reconstruction

- Minimize sqrt((mrec(t->bW) – mtop)2 + (mrec(t->bbbW) – mtop)2)

|  | Cross section
 pb
(no. of events) | Wl
Wqq | |(b)|
< 2.5
PT(b)>  20GeV | Atleast 6 jets | 4 b-jets matched to b-quarks | Reco
W(l+MET)
&
W(2 jets)
65<mjj<95 | Top
(b-jet +W)
150 < mt <200 | Top
(3 b-jets + W)
150< 
mt <
200 | H1
(2 b-jets)

35 <
mh1 
< 65 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| signal | 8.675
(260000) | 76100 | 17803 | 14265 | 6579 | 2634 | 1793 | 892 | 879
1.832 fb |
| ttbb | 3.285
(100000) | 29037 | 15563 | 13124 | 6672 | 2242 | 1074 | 58 | 51
0.104 fb |
|  |  |  |  |  |  |  |  |  |  |

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- June 07

##                     Backups

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- June 07

## Separation of two b-jets used to reconstruct H1 

- Separation of two b-jets used to reconstruct H1

- Les Houches meeting

- June 07

- Les Houches meeting

- June 07