# Presentation: 209376

## Charged Higgs Results from Tevatron

**ICHEP04 Beijing, China**
**Aug 16, 2004**

## Fermilab

**Main Injector**
** ****& Recycler**

**Tevatron**

**Booster**

******p **

**p **

**DØ**

**DØ**

**DØ**

**CDF**

**CDF**

******p source**

**Batavia, Illinois**

**Chicago**

**REACHED  10**

**Fermilab**

## Properties of Doubly Charged Higgs

**Doubly Charged Higgs Bosons appear in several models**
**L-R Symmetric models, Little Higgs model, MSSM **
**Higgs fields can be represented as a triplet in L-R symmetric models (along with neutral and singly-charged Higgs)**
**L-handed and R-handed Higgs fields are possible**

**In L-R Symmetric models, the Higgs triplets are only one of the Higgs multiplets that break symmetry between L- and R- handed weak interactions at low energy.**
**SUSY L-R models suggest low mass for a Doubly Charged Higgs ****(~100 GeV)**

**Properties of Doubly Charged Higgs**

## Production of  H± ±

**Doubly-charged Higgs **
**production cross section is enhanced substantially ****(~35%)**** due to NLO corrections.**** **

**R-handed H++ cross section is smaller by a factor of ~2 due to different value of coupling of these particles to Z bosons.**

**Production of  H****± ±**

**M. Spira & M. M****ü****hlleitner, hep-ph/0305288**

## Decay of  H± ±

- A typical decay

- Couplings like WWH, HHH, HHW and H with hadrons are possible but with very small coupling constants (not considered).

- Experimental Signature of** ****H****± ± **decay

- A pair of like sign di-leptons

**(Yukawa coupling >10****-7****)**

**Decay of  H****± ±**

**Contamination from other Standard Model processes is low because of the requirement of two high p****T ****leptons of same sign.**

## Possible Background Decay Channels

**with charge misidentification, probable for high  **pT tracks

** **

**Possible Background Decay Channels**

**Important modes are those which produce like sign leptons**

**semileptonic decays**

**Hadronic jets**

**leptonic decays**

**WZ/ZZ**

**one electron radiates a photon which then converts to e****+****e****-****, check for photon conversion vertices.**

**W + jets**

**Hadronic jets**

**eliminated by demanding isolated muons****.**

## Search Strategy

**Choose events triggered with two high p****T ****dileptons.**
**electron – energetic EM cluster**
**muon – a high p****T**** ****track matched with a stub in the muon counter + a MIP trace in the EM calorimeter**
**Make more stringent selection offline.**
**Generate signal events in different H****±±**** mass bins covering the search region.**
**Generate Monte Carlo samples for different background decay channels.**
**Use the same selection criteria on experimental data, signal and background samples.**
**If after final selection and background subtraction an excess is seen in experimental data, a discovery is claimed.**
**If no excess is seen, a limit on ****H****±±****  is calculated.**

## Search performed by DØ  experiment

**Offline selection of events :**

**Two muons, matched to good tracks (p****T****> 15 GeV)**

**Calorimeter E****T ****in outer cone around the muon trace should be small**
**p****T ****of tracks around the muon track should be small**

** ********< 2.51 (requirement for events with less than 3 muons)**

-  **Two of the muons should have the ****same charge**

**Preselection**

**113 pb****-1**** integrated luminosity used**

**Search performed by D****Ø****  experiment**

**Isolation**

**Acolinearity**

**Like sign requirement**

**Signal Monte Carlo generation (PYTHIA 6.2)**

**Samples with ****H****±±  ****mass**** ****ranging from**** ****80 GeV to 200 GeV are generated in steps of 10 GeV**

**All efficiencies derived from data**

## Effect of Selection criteria (DØ )

-  preselection

- preselection + like sign muon
- requirement

**Effect of Selection criteria (D****Ø**** )**

**reduces after isolation cut**** **

**101 data events**

## Final Yield (DØ )

**like sign requirement**

**preselection **

**isolation**

**acolinearity**

**+**

**+**

**+**

**Signal (mass = 100 GeV)**

**Total background**

**Data**

**preselection       isolation       acolinearity      like sign**

**9.4                 8.5                 7.5                6.5**

**5254 ****±**** 47      4113 ****± ****43      368 ****± ****14          1.5 ****± ****0.4**

**5168              4133               378                   3**

## Limit on H± ± Mass (DØ )

**Limit calculation depends on mass distribution for signal and background and experimental mass resolution**

**Systematic Uncertainties**** – MC ****(27%),**** theory ****(10%),**
**                                               ****Luminosity ****(6.5%),**** normalization ****(5%)**

**Limit on H****± ±**** Mass (D****Ø**** )**

**(MCLIMIT  - T. Junk, Nucl. Instrum. Methods A 434, 435 (1999))**

**   ****Lower Mass Limit**
**H****±± ****(R) =  ****98.2 GeV**
**H****±± ****(L) = ****118.4 GeV**

## Search for H± ±  (CDF)

**Acceptance = (Kinematic + geometric) x ********trig ********ID**

**Leptons are selected in the central ************region**

**H**_**++**_** ****Acceptance**

**Search in all dilepton decay channals – e e, e ********, ******** ******

##  e e decay channel (CDF)

**Observed Events    =   1**

** ****e e decay channel (CDF)**

**Backgrounds :**

**Z ******** e e, one electron radiates a photon which converts to e****+****e****- **
**Hadronic jets**
**W + jet**
**WZ**

**Low Mass Region           High Mass Region**

**m****ee ****< 80 GeV                       m****ee ****> 80 GeV**

**-0.6**

**+0.9**

**Expected Number**

**5.8**

**m****H**** ****= 100 GeV**

## Di-lepton mass distributions (CDF)

**Total Background (e ********)**

**Di-lepton mass distributions (CDF)**

**Backgrounds :   ****Hadromic jets, W+jet, WZ**

**Total background**** (******** ********)**

**Observed Events = 0**

## Limit Calculation (CDF)

**No events are found in the high mass regions of e e, e ********, ******** ******** samples.  **

** **

**Limit on Higgs mass is calculated using Bayesian method with flat prior for signal and **
**Gaussian prior for background and acceptance uncertainties.**

**Limit Calculation (CDF)**

**H**_**+**_** **_**+**_

**(R) ******** **

**H**_**+**_** **_**+**_

**(L) ******

**(e e = 133 , e ******** = 115 , ******** = 136) GeV**

**( ******** = 115) GeV**

## Summary of mass limits

**  ****Promptly Decaying H****±±**** **

**Summary of mass limits**

**D****Ø**** H****L,R**

** **

**±±**

**Mass limits submitted to Phys. Rev. Lett. in April 2004**

**(hep-ex/0404015)**

**CDF ****H****L,R**

**±±**

**Mass limits**** ****submitted to Phy. Rev. Lett. in June 2004**** **

**(hep-ex/0406073)**

## Long Lived Doubly Charged Higgs (CDF)

** ****Search for particles with c******** > 3 m, no decay within the detector**** **

** ****They will behave like heavy stable particles, (muons but more ionising)**

**Measurement of ionization – ****dE/dx measurement along the charged**
**                                                  ****particle track in ****tracker**** and ****calorimeter****.**

**Background –**** ****Advantage is lack of Standard Model decays.**
**                         ****Events expected from**** ****highly ionizing particles.**

**Muons –**** ****data from cosmic rays (pure muon sample)**

**Hadronic decays for taus**** ****from Monte Carlo sample**

**QCD contribution**** ****calculated from experimental data**

**Long Lived Doubly Charged Higgs (CDF)**

## Long Lived Doubly Charged Higgs (CDF)

**Tracker dE/dx >35 ns**

** ****Tracker dE/dx >35 ns**

**Loose cut :**

**Tight cut :**

** ****Energy (EM) > 0.6 GeV**

** ****Energy (Had.) > 4 GeV**

**Select events which have a good muon track  with p****T**** > 18 GeV.**
**Require a second track with p****T**** > 20 GeV offline.**

**Long Lived Doubly Charged Higgs (CDF)**

**Use loose cuts for setting mass limits**
**And tight cuts for discovery.**

**206 pb****-1**** integrated luminosity used**

**Expected Number**

**10.2**

**6.6**

**3.2**

**2.4**

**100 GeV**

**130 GeV**

**m****H**

## Mass Limit for Long Lived Higgs

**Mass Limit for Long Lived Higgs**

**Bayesian upper limit on**** ****H****±± ****crosssection**

****** ****H****±±**

_**Upper Limit on No. of Signal Events at 95% C.L. for 0 Observed Events**_
**                      ****Total ****H****±± ****Acceptance x Integrated Luminosity**
_** **_

**=**

**For a H****±±**** mass of 130 GeV ****H****±± ****cross section is 0.057 ± 0.0066 ± 0.0030 **

**Mass Limit for Quasi-Stable Doubly charged Higgs is 134 GeV**

## Conclusions

**  ****There is scope for much more improvement in the coming years **

**Conclusions**

** ****Prompt Decays**
**Limits on L-handed Higgs have gone up to ~ ****130 GeV**
**Limits on R-handed Higgs have gone up to ~ ****113 GeV**
**D****Ø****  plans to include e e and e ******** modes in future. **
**Long Lived Higgs**
**Limit on Higgs mass is**** 134 GeV **
**Both experiments will redo the analyses with much more luminosity as good data is being collected at a steady rate at the Tevatron.**

**LEP Results**

**For both promptly decaying and long lived Higgs**
**Mass Limit ~**** 100 GeV**** **

**Tevatron Results**