# Presentation: 394463

## CDF Results for ICHEP 2008

*Chris Hays, *
*Oxford University*
- Fermilab Wine and Cheese
- July 25, 2008

## Tevatron Run II

- Studying the Standard Model at an unprecedented scale
*  **Measurements build up the Standard Model*
*  **Searches probe for cracks*

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## CDF Run II

**145** publications in Run II
**52**** **new results since Moriond
- Analyses with up to 3 fb-1 of data
***Thanks to the accelerator division!***

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Building the Standard Model:Light Quarks and Gluon

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Proton-Antiproton Collisions

- Non-perturbative QCD in every collision
*  **Probe by studying underlying event*
- Separate underlying event from perturbative process using Drell-Yan production

**Define regions relative **
**to boson *****p******T *****: **
**toward, transverse, away**

**Compare charged particle observables to model predictions**

**PYTHIA tune "AW" models underlying event well**
**Standard HERWIG underestimates multiplicity**

**"away"**

**"transverse"**

**"toward"**

***p******T******Z***

**2.7 fb****-1**

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Differential Cross Sections

- Measure momentum & multiplicity distributions from inelastic collisions
*  **Unfold detector response and correct for diffractive background*

**0.5 fb****-1**

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Diffractive W and Z Production

- Focus on clean process of pomeron radiation from antiproton
*  **Study pomeron structure function using weak boson production*
- Roman pots measure outgoing antiproton momentum
-   *Directly measure p**z** of neutrino from W boson decay*

**Single diffraction cross section / total cross section:  **
***W*****'s: 0.95 ± 0.05 ± 0.11%  **
***Z*****'s: 0.85 ± 0.20 ± 0.11% **

**0.6 fb****-1**

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Building the Standard Model:Bottom Quark

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## B-meson Lifetime Measurements

- Lifetimes predicted using heavy quark expansion

**1.0 fb****-1**

***G******F******2***** *****m******b*****5**

****** ****= **

***192 ************3***

**|*****V******cb*****|*****2******  ***** *****A******0****** + A******2                           ******+ A******3***

**(**

**[**

*********QCD***

***m******b***

**)**

***2****** ***

**(**

*********QCD***

***m******b***

**)**

***3****** ***

**]**

***B******c****** c************ ******= 142.5 ******+15.8******-14.8****** ± 5.5 ************m***

***World average c************ ******= 137.7 ± 11.0 ************m***

- New CDF method accounts for trigger bias using data
-   *Trigger requires tracks with large impact parameters*

***B******c****** lifetime in J/************ l***

***B******±****** c************ ******= 498.2 ± 6.8 ± 4.5 ************m***

*Applied to *
*B**±** → **D**0****±*
- Use per-event acceptance function when calculating likelihood
- Can reduce
- systematic
- uncertainties

***J/*********

***B******c***

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## b Lifetime Measurement

- Lifetime ratios predicted to O(1/*m**b**4*):  (***b**0*)/(*B**0*) = 0.88 ± 0.05
- Longstanding tension between prediction and measurements
- 	*World average (2006): 0.804 ± 0.049 *
*	**Recent CDF measurement in J/**** 2**** **above world average*
- New CDF measurement uses ***c**+****-* decay

**1.1 fb****-1**

*********b****** c************ ******= ***
***422.8 ± 13.8 ± 8.8 ************m***

*********(************b******0******)/************(B******0******) =  ***
***0.922 ± 0.039***

- World's
- most precise measurement

*********b***

*********c***

*********-***

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## s Measurement

- Complex Higgs-*q*-*q* Yukawa couplings give rise to CKM matrix

**2.8 fb****-1**

- Wolfenstein
- parametrization

- Unitarity requires combinations of different columns to sum to zero
-   *Triangles in the complex plane*

*********s***

***Not ***
***SM***

- Winter conferences:
-   DØ (2.8 fb-1): 2***s* = (-0.06, 1.20) at 90% CL  (6.6% consistency with SM)
-   CDF (1.4 fb-1): 2***s* = [0.32, 2.82] at 68% CL (15% consistency with SM)
- UTfit:
***  ******"******This is a first evidence of physics beyond the Standard Model"***

***0802.4258***

***PRL 100,***
***161802 ***

***(= 0.02 in SM*********

***0803.0659***

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## s Measurement in J/

*B**s* mixing: Flavor eigenstates oscillate (*B**s**0* ↔ *B**s**0*) with frequency *m* = 17.77 ps-1
- Measure lifetime difference (**) and *CP* asymmetry (∝ sin2***s*) in *J/*** decays
*CP* violation due to interference with and without mixing
***Complication:**** **J/**** not a CP eigenstate*
- Use angular distributions to separate longitudinal, parallel, transverse polarizations
- Combine with decay time and *B**s**0**/B**s**0** *tagging to obtain likelihood for* ****, **** *and* ****s** *

**2.8 fb****-1**

***PRL 97,***
***242003 ***

*3166 B**s**0 **candidates*

- 7% consistency with SM

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Building the Standard Model:Top Quark

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Top Quark Cross Section

- Measurements in "lepton + jets" decay mode with and without *b*-jet tagging

**2.8 fb****-1**

***BR(lepton + jets) = ******30%******   (lepton = e,************)***

**No tagging:**  Neural network separates *tt* from *W* + jets
**b-jet tagging:**  Based on either long *b*-hadron lifetimes
- 		or semi-leptonic *b*-hadron decays

*********tt***** = 6.8 ****± 0.4 (stat) ± 0.6 (sys) ± 0.4 (lum)**** pb**

**No tagging:**

**Lifetime-based *****b*****-jet tagging:**

*********tt***** = 7.2 ****± 0.4 (stat) ± 0.5 (sys) ± 0.4 (lum)**** pb**

*********tt*****  = 8.7 ****± 1.1 (stat) ****+0.9****-0.8**** (sys) ± 0.6 (lum)**** pb**

***b***** → ***********X***** tagging (2.0 fb****-1****):**

*********tt*****  = 7.8 ****± 2.4 (stat) ± 1.5 (sys) ± 0.5 (lum)**** pb**

***b***** → *****eX***** tagging (1.7 fb****-1****):**

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Top Quark Cross Section

- Measurements in "dilepton + jets" decay with and without lifetime-based *b*-jet tagging

**2.8 fb****-1**

***BR(dilepton + jets) = ******5%******   (lepton = e,************)***

- Combine with lepton + jets measurements

*********tt***** = 6.7 ****± 0.8 (stat) ± 0.4 (sys) ± 0.4 (lum)**** pb**

**No tagging:**

**With tagging:**

*********tt***** = 7.8 ****± 0.9 (stat) ± 0.7 (sys) ± 0.5 (lum)**** pb**

- 9% precision
- 8% theory uncertainty

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Top Quark Mass

- Top quark loops contribute to the *W* & *Z* boson masses
-   *m**t**2*-dependent correction drowns ln(*m**H*/*m**Z*) Higgs loop correction
- Need precise top mass measurement to constrain Higgs mass
- Winter conferences: *m**t* = 172.6 ± 1.4 GeV, *m**H* = 87+36-27 GeV

**2.8 fb****-1**

*Measurement in lepton + jets channel most precise (winter conferences:** **m**t** = 172.7 ± 2.1 GeV**)*
- Integrate matrix element over resolutions and unknowns to obtain unbinned likelihood
-   Function of top mass and jet energy scale
- Neural network separates signal from background

*m**t** **= 172.2 ± 1.0 (stat) *
*                 **± 0.9 (JES)*
*                 **± 1.0 (sys) GeV*
*    ** **= 172.2 ± 1.7 GeV*

***Also: Updated measurement in dilepton + jets channel***
***Uses likelihood based on weighting events in ******************1******-******************2****** plane ***

*m**t** = 165.1**+3.3**-3.2** (stat) ± 3.1 (sys) GeV*

***(Tevatron, 0803.1683)***

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Top Quark Mass

- Jet energy scale dominates systematic uncertainty in top mass reconstruction
- Pursue alternative mass measurements largely independent of energy scale
*	**b-jet lifetime:** *proportional to *b*-quark *p**T*
*	**lepton p**T**:** *dependent on *W* *p**T*

**1.9 fb****-1**

*Combination:** m**t** = 175.3 ± 6.2 (stat) ± 3.0 (sys) GeV*

*Lifetime: *
*m**t** = 176.7**+10.0**-8.9** (stat) ± 3.4 (sys) GeV*

*Lepton p**T**: *
*m**t** = 173.5**+8.9**-9.1** (stat) ± 4.2 (sys) GeV*

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Single Top Production

**2.7 fb****-1**

- Top produced weakly in *s*-channel (*tb* = 0.9 pb) or  *t*-channel (*tq* = 2.0 pb)
- Cross section directly measures *V**tb* magnitude
-  *Unique test of CKM unitarity*

- Single top cross section overwhelmed by *W* + jets background
- Advanced techniques required to separate signal from background

*t*-channel likelihood function:
- 7 (10) input variables for 2- (3)-jet final states

*s*-channel likelihood function:
- 6 input variables for 2-jet final state

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Single Top Production

**2.7 fb****-1**

*Matrix-element probability*:
- Combines *s* & *t* channels

*Boosted decision tree:*
- Four trees: 2 or 3 jets with 1 or 2 tags

*Neural network:*
- Four networks:
- 2 or 3 jets with 1 or 2 tags

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Building the Standard Model:Leptons and Electroweak Bosons

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## W Boson Mass

**2.4 fb****-1**

*W* mass precision the primary limitation on indirect Higgs mass constraint
-   *Also constrains other scalars with weak charge (e.g., superparticles)*
- Published measurement with 200 pb-1 has 48 MeV uncertainty (world's best)
- Dominant uncertainties expected to scale with square root of luminosity
***Now analyzing 12x data:***

***PRL 99,***
***151801 ***

***PRD 77,***
***112001 ***

***97k Z → ll events***

***1.4M W → l************ events***

**Expect total uncertainty < 25 MeV**

***Z → *********

***W → e*********

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Building the Standard Model:The Higgs Boson

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## The Higgs Boson

**3.0 fb****-1**

- The last unobserved particle in the standard model
-   *Only fundamental scalar *
*  **Gives fermions and weak bosons their masses*
*  **Responsible for generational mixing*
- Narrow allowed mass region
*  *Direct 95% CL limit:*  **m**H** > 114 GeV*
*  *Indirect 95% CL limit: * **m**H** < 160 GeV*

**Higgs boson at the Tevatron:**

********* ***
***(pb)***

**Higgs boson at CDF:**
*All dominant channels updated*
*New channels added *
*All include improvements: *
*  **scale better than luminosity*

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Higgs Searches (mH ≲130 GeV)

**2.7 fb****-1**

- Use *W/Z* + *H* production at low mass
-   *Significantly suppresses background*
*  **Leptonic boson decays provide further suppression*
*  **Balance loss in cross section with large H → bb BR  *
_***WH***__** → **__***l***__******__***bb***_

**Neural network approach:**
**Six categories based on lepton type and number of *****b*****-tags**

***m******H****** = 115 GeV:***
********* ******< 5.0 x SM  ***
***(5.8 x SM expected)***
***winter conferences: ***
*********< 7.1 x SM expected***

**Added trigger to extend **
**muon coverage**

**Matrix element probability + boosted decision tree:**
**ME likelihoods among 21 inputs**

********* ******< 5.8 x SM  ***
***(5.6 x SM expected)***

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Higgs Searches (mH ≲130 GeV)

**2.4 fb****-1**

_***ZH***__** → **__***llbb***_

**2-dimensional neural network:**
**13 input variables separate *****ZH***** from *****tt***** and *****Z*****+jets **

***m******H****** = 115 GeV:***
********* ******< 11.6 x SM  ***
***(11.8 x SM expected)***
***winter conferences: ***
*********< 16 x SM expected***

**Matrix element probability:**

***m******H****** = 120 GeV:***
********* ******< 14.2 x SM  ***
***(15.0 x SM expected)***

**Less data and lepton coverage**
**Better sensitivity for overlap sample**

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Higgs Searches (mH ≲130 GeV)

**2.1 fb****-1**

_***ZH***__** → **__******__***bb + WH***__** → **__***l***__******__***bb***_

***m******H****** = 120 GeV:***
********* ******< 38 x SM  ***
***(40 x SM expected)***

**Added H1 algorithm using charged-particle tracks to improve jet energy resolution**

***m******H****** = 115 GeV:***
********* ******< 7.9 x SM  ***
***(6.3 x SM expected)***
***winter conferences: ***
*********< 8.3 x SM expected***

**7 inputs to neural network **

_***WH + ZH***__** → **__***qqbb ***_

**Matrix element procedure**

- ME discriminant

- CDF Run II Preliminary

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Higgs Searches (mH ≳130 GeV)

**3.0 fb****-1**

- Traditionally focus on direct Higgs production
-   *High branching ratio to WW*
*  **H → WW → l****l**** low-background final state*
- Additional sensitivity with new modes
* *
_***H***__** → **__***WW***_

**Neural network:**
**Uses matrix element likelihood as a discriminant in events with no jets**

**Large boson branching ratio to quarks**
**Provides 30% additional acceptance**

***qqH***

_***WH + ZH + qqH***__** → **__***qqWW***_

***m******H****** = 160 GeV:***
********* ******< 1.6 x SM  ***
***(2.0 x SM expected)***
***winter conferences: ***
*********< 2.5 x SM expected***
********* ******< 6.9 x SM  ***
***(4.6 x SM expected)***
***Combination:***
********* ******< 1.6 x SM******  ***
***(1.8 x SM expected)***

**Also: *****WH***** → *****WWW***** → *****l************l************l*********
********* ******< 33 x SM  ******(33 x SM expected)***

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Breaking the Standard Model:Supersymmetry

- ±

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Stop and Sbottom Production

**2.7 fb****-1**

*m**gluino **- m**sbottom* = 20 GeV

- Supersymmetry solves the hierarchy problem, predicts coupling unification, has
- 	a dark matter candidate, and is required by string theory
-   *Superpartners of every particle, differing in spin by 1/2*
- Searches for stop and gluino-mediated sbottom
-   production

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Chargino + Neutralino and Sneutrino Production

**2.0 fb****-1**

- _Chargino + neutralino search_
- Spin 1/2 partners of gauge and Higgs bosons
-   mix to form charginos and neutralinos

**Limits set in *****m******0*****-*****m******1/2***** plane of constrained SUSY**

- _Sneutrino search_
- Resonant production if *R*-parity violated

***e************, e************, ************ *****final states**

***m************ > ***
***586 GeV (e************)***
***487 GeV (e************)***
***484 GeV (************)***
***for couplings 0.05-0.1***

******

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Breaking the Standard Model:Neutral Resonances

*'*

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Resonance Decays to Dimuons

**2.5 fb****-1**

- New U(1) symmetry ubiquitous in models: versions of supersymmetry, unified theories
- Excited graviton states predicted in warped extra dimension theories
*Both predict resonances decaying to dileptons, likely at Electroweak mass scale*

*'*

**Winter conferences:  dielectron search showed excess at mass around 240 GeV**
**	****	****   ****0.6% probability to be a background fluctuation**

**New search in dimuon channel: similar sensitivity to a resonance with this mass**

**Probe *****1/m***** spectrum: resolution constant vs *****1/m***

*Most significant excess at 103 GeV*
*6.6% probability to be due to background*

- Set mass limits on *Z'* and gravitons

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Breaking the Standard Model:A Fourth Generation

*'*

*'*

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Fourth Generation Top Quark

**2.8 fb****-1**

*t'* can lead to large ***s* and *D**0* mixing        (Hou, Nagashima, and Soddu, PRD 76, 016004)
- Search for *t'*  in lepton + jets final state
- Reconstruct hypothesized *t'* mass and search in plane of mass vs total transverse energy

*'*

- 1% consistency between data and SM at this mass

***m******t'****** > 311 GeV***

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## CDF Run II:ICHEP 2008

**Reaching the peak of the physics**
**Broad program with many exciting results**
**New results not shown today:**
*Z* + jets cross section
- Inclusive photon cross section
- X(3872) mass measurement
- Search for narrow resonances below the **
- Search for *B**s/d* → *e***
- Gluon fusion fraction of top production
*W* helicity measurement combination
- Limits on top decay to non-SM final states
- Anomalous single top production

- Search for charged Higgs in top decays
- Anomalous ZZZ couplings
- Search in photon + missing *p**T* + jet
- Search in photon + missing *p**T* + *b*-jet
- Search in photon + missing *p**T* + *b*-jet + lepton
- Maximal-flavor-violation in same-sign top production
- Technirho production
- Leptoquark production

**See ****http://www-cdf.fnal.gov/physics/S08CDFResults.html**** for more details**

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## The Standard Model at ICHEP 2008

*Closing in on the final piece*
- Are we seeing a new wrinkle?

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Backup

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Top Quark Pair Production

- Standard Model predicts 85% *qq* annihilation and 15% gluon fusion

**2.0 fb****-1**

***Leptons go in same direction when J = 0***

***J = 1***

***J = 0***

***t spin: ***

***l******+****** momentum:***

- Top quark decays via *W**+*: left-handed top decays to right handed *l**+*

***t spin: ***

***l******-****** momentum:***

- Measure gluon fusion fraction through lepton azimuthal correlation

***qq annihilation***

***gluon fusion***

***Distribution ***
***sculpted by event selection***

***gluon fusion fraction:***
***53******+36******-38******%***

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008

## Anomalous ZZZ Couplings

**1.9 fb****-1**

- C. Hays, Fermilab Wine and Cheese

- July 25, 2008