| 8 |
|
with $Z \to ee$ and $Z \to \mu\mu$. A separate search for new physics in the non-\Z |
| 9 |
|
sample is described in~\cite{ref:GenericOS}. |
| 10 |
|
|
| 11 |
< |
We search for new physics in the final state of \Z plus two or more jets plus missing transverse energy (MET). We reconstruct the \Z boson |
| 12 |
< |
in its decay to $e^+e^-$ or $\mu^+\mu^-$. Our search regions are defined as MET $\ge$ \signalmetl~GeV (loose signal region) and MET $\ge$ \signalmett~GeV (tight signal region), and two or more jets. We use data driven techniques to predict the |
| 13 |
< |
standard model background in this search region. |
| 14 |
< |
Contributions from Drell-Yan production combined with detector mis-measurements that produce fake MET are modeled via MET templates based on photon plus jets events. |
| 11 |
> |
We search for new physics in the final state of \Z plus two or more jets plus missing |
| 12 |
> |
transverse energy (MET). We reconstruct the \Z boson |
| 13 |
> |
in its decay to $e^+e^-$ or $\mu^+\mu^-$. Our search regions are defined as |
| 14 |
> |
MET $\ge$ \signalmetl~GeV (loose signal region) and MET $\ge$ \signalmett~GeV |
| 15 |
> |
(tight signal region), and two or more jets. We use data driven techniques to predict the |
| 16 |
> |
standard model background in these search regions. |
| 17 |
> |
Contributions from Drell-Yan production combined with detector mis-measurements that |
| 18 |
> |
produce fake MET are modeled via MET templates based on photon plus jets events. |
| 19 |
|
Top pair production backgrounds, as well as other backgrounds for which the lepton |
| 20 |
< |
flavors are uncorrelated such as di-bosons ($VV$) and DY$\rightarrow\tau\tau$, are modeled via $e^\pm\mu^\mp$ subtraction. |
| 20 |
> |
flavors are uncorrelated such as WW and DY$\rightarrow\tau\tau$, are |
| 21 |
> |
modeled via $e^\pm\mu^\mp$ subtraction. |
| 22 |
|
|
| 23 |
< |
As leptonically decaying \Z bosons is a signature that has very little background, they provide a clean final state in which to search for new physics. |
| 24 |
< |
Because new physics is expected to be connected to the Standard Model Electroweak sector, it is likely that new particles will couple to W and Z bosons. |
| 25 |
< |
For example, in mSUGRA, low $M_{1/2}$ can lead to a significant branching fraction for $\chi_2^0 \rightarrow Z \chi_1^0$. |
| 23 |
> |
As leptonically decaying \Z bosons is a signature that has very little background, |
| 24 |
> |
they provide a clean final state in which to search for new physics. |
| 25 |
> |
Because new physics is expected to be connected to the Standard Model Electroweak sector, |
| 26 |
> |
it is likely that new particles will couple to W and Z bosons. |
| 27 |
> |
For example, in mSUGRA, low $M_{1/2}$ can lead to a significant branching fraction |
| 28 |
> |
for $\chi_2^0 \rightarrow Z \chi_1^0$. |
| 29 |
|
In addition, we are motivated by the existence of dark matter to search for new physics with MET. |
| 30 |
< |
Enhanced MET is a feature of many new physics scenarios, and R-parity conserving SUSY again provides a popular example. The main challenge of this search is therefore to |
| 30 |
> |
Enhanced MET is a feature of many new physics scenarios, and R-parity conserving SUSY |
| 31 |
> |
again provides a popular example. The main challenge of this search is therefore to |
| 32 |
|
understand the tail of the fake MET distribution in \Z plus jets events. |
| 33 |
|
|
| 34 |
< |
The basic idea of the MET template method~\cite{ref:templates1}\cite{ref:templates2} is to measure the MET distribution in a control sample which has no true MET and a similar topology to the signal events. |
| 34 |
> |
The basic idea of the MET template method~\cite{ref:templates1}\cite{ref:templates2} is |
| 35 |
> |
to measure the MET distribution in a control sample which has no true MET and a similar |
| 36 |
> |
topology to the signal events. |
| 37 |
|
In our case, we choose a photon sample with two or more jets as the control sample. |
| 38 |
< |
Both the control sample and signal sample consist of a well measured object (either a photon or a leptonically decaying $Z$), which recoils against a system of hadronic jets. |
| 38 |
> |
Both the control sample and signal sample consist of a well measured object (either a |
| 39 |
> |
photon or a leptonically decaying $Z$), which recoils against a system of hadronic jets. |
| 40 |
|
In both cases, the instrumental MET is dominated by mismeasurements of the hadronic system. |
| 41 |
|
|
| 42 |
|
This note is organized as follows. |
