| 3 |
|
Standard Model background rates from true tau leptons are typically the same |
| 4 |
|
order of magnitude as the expected signal rate in many searches for new |
| 5 |
|
physics. The challenge of doing physics with taus is driven by the rate at |
| 6 |
< |
which objects are incorrectly tagged as taus. In paticular, quark and gluon |
| 6 |
> |
which objects are incorrectly tagged as taus. In particular, quark and gluon |
| 7 |
|
jets have a significantly higher production cross-section and events where |
| 8 |
|
these objects are incorrectly identified as tau leptons can dominate the |
| 9 |
|
backgrounds of searches for new physics using taus. Efficient identification |
| 10 |
< |
of hadronic tau decays and and low misidentification rate for quarks and gluons |
| 10 |
> |
of hadronic tau decays and low misidentification rate for quarks and gluons |
| 11 |
|
is thus essential to maximize the significance of searches for new physics at |
| 12 |
|
CMS. |
| 13 |
|
|
| 14 |
< |
New physics signals may be discovered through tau lepton hadronic decay channels |
| 15 |
< |
in early CMS data. The tau lepton plays a paticularly important role in |
| 16 |
< |
searches for Higgs bosons. In the Minimal Supersymmetric Model (MSSM), the |
| 17 |
< |
production cross--section is enhanced by the parameter $\tan\beta$. The |
| 18 |
< |
coupling of the MSSM Higgs to the tau lepton is also enchaced. \fixme(finish |
| 19 |
< |
this) |
| 14 |
> |
%New physics signals may be discovered through tau lepton hadronic decay channels |
| 15 |
> |
%in early CMS data. The tau lepton plays a paticularly important role in |
| 16 |
> |
%searches for Higgs bosons. In the Minimal Supersymmetric Model (MSSM), the |
| 17 |
> |
%production cross--section is enhanced by the parameter $\tan\beta$. The |
| 18 |
> |
%coupling of the MSSM Higgs to the tau lepton is also enchaced. \fixme(finish |
| 19 |
> |
%this) |
| 20 |
|
|
| 21 |
|
%The tau plays a paticularly important role in the search for Higgs |
| 22 |
|
%boson particle. In the Standard Model (SM), the Higgs boson couplings to fermions |
| 31 |
|
enough to decay to hadrons. The hadronic decays compose approximately 65\% of |
| 32 |
|
all tau decays, the remainder being split nearly evenly between $\tau^{-} |
| 33 |
|
\rightarrow \mu^{-} \bar \nu_\mu \nu_\tau$ and $\tau^{-} \rightarrow e^{-} \bar |
| 34 |
< |
\nu_e \nu_\tau$. The hadronic decays typically decay to one or three charged |
| 34 |
> |
\nu_e \nu_\tau$. The hadronic decays are typically composed of one or three charged |
| 35 |
|
pions and zero to two neutral pions. The neutral pions decay almost |
| 36 |
|
instantaneously to pairs of photons. |
| 37 |
|
|
| 38 |
|
In this note, we will describe a technique to identify hadronic tau decays. Tau |
| 39 |
|
decays to electrons and muons are difficult to distinguish from electrons and |
| 40 |
|
muons produced in $pp$ collisions. Analyses that use exclusively |
| 41 |
< |
non-hadronically decaying taus typically require that the leptonic ($e,\mu$) |
| 41 |
> |
non--hadronically decaying taus typically require that the leptonic ($e,\mu$) |
| 42 |
|
decays be of opposite flavor. The discrimination of hadronic tau decays from |
| 43 |
|
electrons and muons is described in~\cite{PFT08001}. With the Tau Neural |
| 44 |
< |
Classifier, we aim to improve the identification of true hadronic tau decays |
| 45 |
< |
associated with a collimated jet containing either one or three tracks |
| 46 |
< |
reconstructed in the pixel and silicon strip tracker, plus a low number of |
| 47 |
< |
neutral electromagnetic showers reconstructed in the calorimeter. |
| 44 |
> |
Classifier, we aim to improve the discrimination of true hadronic tau decays |
| 45 |
> |
from quark and gluon jets using a neural network approach. |
| 46 |
> |
|
| 47 |
> |
%associated with a collimated jet containing either one or three tracks |
| 48 |
> |
%reconstructed in the pixel and silicon strip tracker, plus a low number of |
| 49 |
> |
%neutral electromagnetic showers reconstructed in the calorimeter. |
