%
%
\section{The Canadian CDF-II Physics Program}

The multi-purpose CDF detector makes possible the pursuit of a very
broad physics program that is progressing on several principal fronts:
high-precision inquiry into electroweak physics observables of top
quarks and intermediate vector bosons; exploration of both
perturbative and nonperturbative QCD, including measurements of
heavy-quark hadroproduction; and energy-frontier searches for physics
beyond the Standard Model, a description of Nature that is generally
reasoned to be incomplete.

Canada's CDF group is engaging in physics analyses that span this
breadth.  Below, we summarise the significant Canadian efforts
underway using the early Run-II data; we follow this with a discussion
of the Tevatron luminosity program and its projected physics reach.


\subsection{Top Quark Physics Studies}
\label{sect:top}

Since the discovery of the top quark during Run~I of the Fermilab
Tevatron, emphasis has turned to the precise characterization of its
properties.  Given the relatively small samples collected in Run~I,
much remains to be discovered about this unusually massive and highly
short-lived fermion.  The current Run~II dataset represents an order
of magnitude increase in statistics over the world's previous top
quark sample and, together with new analysis approaches and improved
detector functionality, is enabling precision measurements of this
exotic particle.  The CDF Run~II upgrades have enhanced the top quark
yield per unit of time-integrated luminosity by both extending and
improving the lepton identification systems, and by significantly
improving the bottom quark tagging capability.  Combined with the
additional time-integrated luminosity and the higher cross section
afforded by the increase in centre-of-mass energy from 1.8 to 2.0~TeV,
we are now able to study samples of top-quark candidates of order
$10^3$ in number.

\subsubsection{Top Mass}

The top quark's great mass is arguably its most striking feature, one
that figures prominently in radiative corrections to Standard Model
descriptions of electroweak observables.  A precise understanding of
the top mass is therefore crucial to providing constraints on the
Higgs boson mass and consistency checks of the Standard Model, both
with much sensitivity to new physics.

The Canadian top-mass effort (Arguin, Sabik, Savard, and Sinervo) is
focussing on the lepton~+~jets and dilepton channels of $t\bar{t}$ 
production and decay, whereby both top quarks decay into $b$-quark jets
and $W$ bosons. In the dilepton channel, both $W$ bosons decay leptonically
whereas in the lepton~+~jets channel, one $W$ boson decays 
leptonically and the other hadronically. The resultant topologies
consist of one or two charged leptons, missing transverse energy due to the
neutrino, and two to four jets.
%The lepton~+~jets channels represent the golden modes of the possible
%$t\bar{t}$ final states by virtue of the fact that they represent
%$\sim 30$\% of the branching fraction and have relatively low
%backgrounds.
A major challenge to measuring the top mass is the
complicated reconstruction of the final state required. 
In the case of the dilepton channel, the two neutrinos 
are not measured, which requires solving a kinematically
underconstrained problem. For the lepton~+~jets case,  CDF's
b-jet-tagging capabilities are employed, with efficiencies of
approximately 40\%, to reduce these combinatorics significantly.  A
second major challenge is overcoming the largest systematic
uncertainty, namely that due to the jet energy scale.  Uncertainties
in the jet energy scale arise from model dependence in our
descriptions of fragmentation and the particle responses attributed to
jet behaviour in our detector.  A major component of the top mass
analyses, contributed by our group, is a set of top-specific
jet-energy corrections, corrections that account for fragmentation
differences between light-quark and $b$-quark jets, that are tuned to
the non-flat $p_T$ spectrum of jets from $t\bar{t}$ decay, and that
supply the mass reconstruction fitting machinery with top-specific
jet-energy resolutions.  Nevertheless, with recent increases in
time-integrated luminosity, the systematic uncertainty associated with
the jet energy scale has alone become comparable to the statistical
uncertainty.

Our Canadian group has been prominent in pioneering a novel means to
reduce the jet energy scale (JES) uncertainty in a statistically
scalable way by introducing the {\it in situ} reconstruction of
hadronic $W$ boson candidates embedded in $t\bar{t}$ candidate final
states.  In the conventional template analysis, top mass candidates
are reconstructed kinematically for each selected event and compared
with a sequence of Monte Carlo top-mass templates to extract the
best-fit mass.  In the new extended approach, templates of both
top-quark and $W$-boson mass are used to fit for the top-quark mass
and jet energy scale simultaneously.  Refer to Fig.~\ref{fig:mtop}.
This approach has resulted in the world's single best measurement of
the top quark mass, $(173.5\, ^{+2.7}_{-2.6}[{\rm stat}]\pm 2.5 [{\rm
  JES}]\pm 1.3[{\rm syst}])$~GeV/$c^2$, which is alone more precise
than the previous world average value.
% xxx Check top mass value!

\begin{figure}
\begin{center}
\epsfig{figure=datafit_mt.eps,height=2.1in}
\hskip 0.2in
\epsfig{figure=datafit_mjj.eps,height=2.1in}
\end{center}
\caption{ The reconstructed {\bf[left]} top-quark and {\bf[right]}
  $W$-boson mass distributions fit for simultaneously and plotted with
  the expected distributions from the Monte Carlo signal template at
  the fit mass and the background template.  The $m_t$ and $m_W$
  distributions are shown for different categories of $b$-jet tags,
  namely number of $b$ tags and tight (T) or loose (L) requirements.}
\label{fig:mtop}
\end{figure}


\subsubsection{$t\bar{t}$ Production Cross Section}

The top quark production cross section at the Tevatron is predicted 
within the Standard Model with an uncertainty of approximately
$<15$\%, %put reference here? xxx
and is expected to increase by $\sim 30$\% due to the increase in
centre-of-mass energy from 1.8 to 1.96~TeV.  The experimental
measurement of the cross section using a particular final-state
topology is potentially sensitive to new physics governing the
production aspect, {\it e.g.}, a heavy resonance decaying to
$t\bar{t}$ pairs; similarly, a marked departure from the Standard
Model prediction could also signal the presence of a novel mechanism
for the decay aspect, {\it e.g.}, supersymmetric particles in the
final state. %put in references for these? xxx

CDF has been pursuing several measurements of the top-pair production
cross section in the dilepton, lepton~+~jets, and all-hadronic
channels.  Using the dilepton mode, $p\bar{p} \to t\bar{t} \to
b\ell^+\nu_\ell \bar{b}\ell^{\prime -}\bar{\nu}_{\ell^\prime}$,
Canadians Savard, Spreitzer, and Tafirout have developed techniques to
% check names xxx
measure the $t\bar{t}$ production cross section with greater
acceptance using a sample with tight cuts on one lepton candidate and
generic isolated-track criteria on the other track.  Although it
results in some increase in the background contribution, this method
brings a gain in the overall acceptance as well as an ability to
accept hadronic decays of the $\tau$ lepton.  This analysis was the
first top physics paper published by the Tevatron experiments. An
updated measurement was recently obtained using $\sim$360~pb$^{-1}$ 
giving $\sigma_{t\bar{t}} = 9.9
\, ^{+2.2}_{-2.0}[{\rm stat}]\, ^{+1.3}_{-1.3} [{\rm syst}]\pm
0.6[{\rm lumi}]$~pb, assuming ${\cal
  B}(W\to\ell\nu) = 10.8$\%.

In the context of CDF $t\bar{t}$ production cross-section
measurements, Buzatu and Warburton are assessing algorithms used to
select primary vertices with respect to the high-$p_T$ leptons in
candidate $t\bar{t}$ events.  The efficient selection of the correct
primary vertex is important for the many analyses that employ
secondary-vertex $b$-tagging, and is anticipated to undergo refinement
as the instantaneous luminosity increases, with an attendant increase
in event pile-up.

\subsubsection{Single-Top Production}

Whereas the discovery of the top quark was made possible by observing
$t\bar{t}$ pairs produced via the strong interaction, single top
quarks can also be produced at the Tevatron by electroweak processes.
The cross section of a virtual $W^*$ propagator decaying into a top
and bottom quark is proportional to the CKM matrix element $\left|
  V_{tb} \right|^2$ and has sensitivity to non-standard couplings of
the top quark, making it an ideal observable in our search to uncover
new physics.  Canadian researchers Savard, B.~Stelzer, and Trischuk
have conducted an initial search for single-top production, setting a
limit $\sigma < 17.8$~pb at 95\% C.L.~in the combined $s$ and $t$
channels using 162~pb$^{-1}$, the first limit obtained using Run~II of
the Tevatron.
%  Refer to Fig.~\ref{fig:singletop}.  
The significant
additional luminosity expected from Run~II along with new analysis 
techniques developed by our group portends the exciting
prospect for the first observation of electroweak top prodcution.

%\begin{figure}
%\begin{center}
%\epsfig{figure=singletop_Ht_data.eps,height=2.0in}
%\hskip 0.3in
%\epsfig{figure=Ht_fitresult_data.pdf,height=2.0in}
%\end{center}
%\caption{ The $H_T$ (or scalar $\Sigma E_T$ over all jets, lepton, and
%  \MEt\ in the event) distribution for 162~pb$^{-1}$ of Run-II data,
%  with Monte Carlo templates representing calculated contributions for
%  single-top signal and backgrounds.  The $H_T$ variable is used
%  because both the $s$-channel and $t$-channel single-top processes,
%  which are combined in the figure, exhibit similar distributions in
%  this quantity. }
%\label{fig:singletop}
%\end{figure}


\subsubsection{$t\bar{t}$ Production Mechanisms}

A highly challenging analysis is seeking to study $t\bar{t}$
production characteristics, specifically the ratio of $t\bar{t}$ cross
section due to gluon-gluon fusion to that due to quark-antiquark
annihilation.  Pashapour and Sinervo are investigating techniques and
variables to discriminate between the two production mechanisms by
examining initial-state gluon radiation properties while minimizing
model dependence.  In particular, track and forward-jet multiplicity
observables are showing promise in providing separation between gluon-
and quark-enriched events.
%  Refer to Fig.~\ref{fig:qq_gg_tt}.  
The
study aims to measure the ratio $\sigma(gg\to t\bar{t}) / \sigma
(q\bar{q}\to t\bar{t})$ with a precision of 5$-$10\%.

%\begin{figure}
%\begin{center}
%\epsfig{figure=tt_nt_050603.eps,height=2.0in}
%\hskip 0.3in
%\epsfig{figure=nt_vs_qq_gg_frac_w_jet.eps,height=2.0in}
%\end{center}
%\caption{ a) {\bf[left]} Track multiplicity distributions from Monte
%  Carlo simulations of $t\bar{t}$ production due to $gg$ and
%  $q\bar{q}$ production processes.  A similar trend is observed in jet
%  multiplicity.  b) {\bf[right]} Mean low-$p_T$ track multiplicities
%  versus the fraction of gluon-rich events to $q\bar{q}$ events for
%  (from left to right) $W + 0$, $W + 1$, and $W + 2$ jet samples,
%  followed by inclusive jet samples with leading $E_T$ thresholds
%  increasing by 20~GeV from 100~GeV to 200+~GeV.}
%\label{fig:qq_gg_tt}
%\end{figure}


\subsection{$W$ Boson Physics Studies}

A precise mass measurement of the $W$ boson, by virtue of the fact
that its mass and that of the top quark are connected to the Higgs
boson mass through radiative corrections, can help to provide both
constraints on the Higgs mass and a valuable consistency check of the
Standard Model.  The $W$ mass is also sensitive to new physics from
exotic particles populating loops in the $W$ propagator.

Canadian CDF members Stelzer-Chilton, Trischuk, and Vollrath are
conducting a measurement of the $W$-boson mass using candidates in the
$W \to \mu\nu_\mu$ channel both in terms of transverse mass ($m_T$)
and transverse momentum ($p_T$).  For this analysis the determination
of the muon momentum scale is critical. We have been heavily involved
in understanding the tracker alignment and calibrating the momentum
scale using $J/\psi$ and $\Upsilon$ control samples. Further, the
$m_T$ distribution cannot be predicted analytically, necessitating the
use of Monte Carlo line shape predictions.  Currently, no NLO QCD
Monte Carlo calculation includes ${\cal O}(\alpha)$ electroweak
corrections.  Our group has developed techniques to merge the output
from the {\sc resbos} QCD generator numerically with that from the
{\sc wgrad/zgrad} QED generator providing improved understanding of
one of the few $W$ mass systematics that is not naturally reduced by
having larger statistics control samples.

The technique of instead using the $p_T$ distribution has an advantage
over the traditional $m_T$ approach in that it is less sensitive to
detector related effects such as calorimeter response and resolution.
In the past the charged lepton $p_T$ measurement was used as a cross
check; however, now due to better QCD Monte Carlo generators we are
able to model the $p_T(W)$ spectrum (which the $p_T(\mu)$ measurement
is sensitive to) more reliably and we observe that the $p_T$
measurement has slightly lower systematic uncertainties than the
transverse mass.  This work will be very useful for future $W$ mass
measurements at hadron colliders since the transverse mass measurement
will continue to degrade in higher luminosity environments due to
pileup, and the $p_T$ measurement will be the primary method for
measuring the $W$ mass.

%\begin{figure}
%\begin{center}
%\epsfig{figure=wm_pt_fit.eps,height=2.0in}
%\end{center}
%\caption{The muon transverse momentum distribution for
%  $W\to\mu\nu_\mu$ candidates.  }
%\label{fig:wm_pt_fit}
%\end{figure}


% \begin{figure}
% \begin{center}
% %\leavemode
% \epsfxsize=4.0in
% %\epsffile{w_mt_new.pdf}
% \end{center}
% \caption{Transverse mass distribution of $W\to\mu\nu_\mu$ candidates in
%   72~pb$^{-1}$ of Run~II data.  The background sources (from
%   $Z\to\mu\mu$, $W\to\tau\nu_\tau$, cosmic-ray, and QCD dijet
%   processes) constitute a total of $\sim$11\% of the signal (shown
%   in grey).}
% \label{fig:trans_mass_W}
% \end{figure}


\subsection{Exotics, QCD, and Higgs Physics Studies}

\subsubsection{Searches for Exotic Particles}

Supersymmetry (SUSY) is one of the most popular candidates for physics
beyond the Standard Model.  In one range of SUSY theories, those for
which R-parity is conserved, pair-produced squarks and gluinos
decay, producing energetic hadronic jets and weakly interacting stable
neutralinos.  The neutralinos would escape detection by the CDF
calorimeter, thus leaving missing transverse energy.

The IPP group (MacQueen and Orr) is exploring signatures for SUSY in
searches for $R$-parity conserving supersymmetry signals using
jet~+~\MEt~signatures.  In this search, a signal region with high
missing transverse momentum and three or more energetic jets is
defined
%  Refer to Fig.~\ref{fig:susy}.  
%The signal region is treated
as a ``blind box'', and will not be examined until the backgrounds to
the signal are fully understood in nearby control regions and the cuts
on the data are optimised.  Using the significantly increased data
sample available from Run~II, either existing limits on squark and
gluino masses will be significantly extended in a model-independent
way, or evidence for SUSY will be seen.

%\begin{figure}
%\begin{center}
%\epsfig{figure=susygen59-metht.eps,height=2.0in}
%\hskip 0.3in
%\epsfig{figure=emet0d-metht.eps,height=2.0in}
%\end{center}
%\caption{ Plots of missing transverse energy versus $H_T$ (defined in
%  Fig.~\protect\ref{fig:singletop}) in GeV for events with three or
%  more jets in a) {\bf[left]} a Monte Carlo calculation for
%  gluino-squark production using mSUGRA parameters m(up squark) =
%  375~GeV and m(gluino) = 300~GeV and b) {\bf[right]} a data sample of
%  $\sim$320~pb$^{-1}$ in which the upper-right corner is blanked due
%  to the blinded region.}
%\label{fig:susy}
%\end{figure}

% xxx Needs work, greater specificity!  Check with Pierre.
Beauchemin and Savard have also been working on the development of
generic signature-based searches involving significant missing
transverse energy, which figures prominently in the signals for many
exotica, including large extra dimensions, SUSY-associated or other
dark matter, and escaping gravitons (in models with TeV-scale
gravity).  Initial studies, which have involved low numbers of jets,
have extended existing limits of models with Large Extra Dimensions. 
With the help of Krishna-Prasad, these studies are being extended to 
include higher jet multiplicities and to make use of the expected 
larger future Tevatron data samples that will
enhance the discovery reach of this approach.


\subsubsection{QCD and Higgs Studies}

The exciting possibility of detecting a light Higgs boson has been the
focus of much attention.  Double diffractive collisions, in which the
final state contains only intact protons that escape the central
detectors, could allow a precise measurement of the Higgs mass near
200~GeV using the missing mass method on protons tagged with Roman pot
detectors, far downstream of the interaction region.  While this
method, which applies only to exclusive Higgs production, is expected
to have a rate too low to be observable at the Tevatron, the inclusive
process has recently been estimated to be detectable. Hamilton and
Pinfold are investigating the use of the doubly diffractive channel as
a clean Higgs production environment, work that is expected to inform
similar searches in diffractive production at the LHC.  In
Fig.~\ref{fig:diffractive_bjetxs}, a peak representing an absence of particle
multiplicity in both opposing forward directions is suggestive of
pomeron exchange; the ridges along the axes represent single
diffraction candidates, and the remaining events are deemed to be
non-diffractive.

\begin{figure}
\begin{center}
\epsfig{figure=inc_mp_nhits.eps,height=1.75in}
\hskip 0.1in
\epsfig{figure=Greg_APS05_bjetxs.eps,height=1.75in}
\end{center}
\caption{{\bf [left]} Particle multiplicity in the east miniplug (MP)
  vs.~the west MP for events with two loose photon candidates.  The
  peak near (0,0) is suggestive of double-pomeron exchange. {\bf
    [right]} Normalised $b$-jet cross-section distribution in a CDF-II
  sample of $\sim$340~pb$^{-1}$.}
\label{fig:diffractive_bjetxs}
\end{figure}

Intimately linked to searches for the Higgs boson in the low-mass
region, where the $H \to b\bar{b}$ mode dominates, is a deeper
understanding of QCD jets, in particular high-momentum $b$-quark jets.
Pairs of $b$ quarks can also be produced through purely QCD
interactions at rates orders of magnitude greater than those from
Standard Model Higgs decays; this underscores a need for well
understood $b$-quark production cross sections and QCD jet properties.
By demanding the presence of an associated $W$ boson, the QCD
background can be markedly reduced, and indeed the $Wb\bar{b}$ cross
section is a promising avenue to setting the world's best lower limit
on the Higgs mass with CDF.\footnote{Note that this topology is
  complementary to that for the single-top production described in
  Section~\ref{sect:top}, where the $W^*\to t\bar{b}$ channel mimics
  the associated $WH$ Higgs production final state.}  As a component
of this larger study, Snihur, Warburton, and Williams are analysing
the inclusive $b$-jet production cross section at high transverse
momenta using a jet-probability $b$-tagging method.  Refer to
Fig.~\ref{fig:diffractive_bjetxs}.  Work is going into understanding
the trigger efficiencies and prescales, as well as using
jet-probability tagging information to provide separation between
different quark-jet flavours.

%\begin{figure}
%\begin{center}
%\epsfig{figure=Greg_APS05_bjetxs.pdf,height=2.0in}
% xxx Fixing bounding box for this figure!
%\end{center}
%\caption{ A preliminary normalized $b$-jet cross-section distribution
%  using a sample of $\sim$340~pb$^{-1}$ of CDF Run-II data.}
%\label{fig:bjetxs}
%\end{figure}

Of particular relevance to energy-frontier electroweak and QCD studies
is the development of a deeper understanding of the production of an
intermediate vector boson in association with $n$ QCD jets.  Mazini is
examining the production of $Z$($W$)~+~$n$ jets processes to test
higher order QCD corrections to electroweak effects; these processes
pose a background to top, Higgs, and SUSY signatures.  Although the
$Z$~+~$n$ jets process may be favourable given the cleaner signal (no
missing energy, good kinematical reference), it is statistically
limited and will therefore benefit from the envisaged enlarged
Tevatron data samples.

Another enticing low-mass Higgs signature observable, under study by
Lai and Sinervo, is the $p\bar{p} \to t\bar{t}H$ final state.
Although the cross section for a Higgs of mass 120~GeV is predicted to
be only $\sim$4.8~fb, this mode's distinctive topology (which requires
the efficient identification of leptons and $b$-quark jets), data from
additional Run~II Tevatron operation, and our pioneering work on a new
high-efficiency ``combined tagger'' will enable us to achieve increased
signal-to-background ratios and better characterise the backgrounds in
this channel. 
% Fig.~\ref{fig:ttH} describes our acceptance as a
%function of Higgs boson mass.  
This measurement will be pursued further by the LHC experiments.

%\begin{figure}
%\begin{center}
%\epsfig{figure=lai_ttH_acceptance.eps,height=2.0in}
%\end{center}
%\caption{ Calculated CDF~II acceptance for the $t\bar{t}H$ channel as
%  a function of the Higgs boson mass.}
%\label{fig:ttH}
%\end{figure}


\section{Tevatron Luminosity Program and Projected Physics Reach}

The early Run-II results that are currently entering publications are
primarily based on data samples having time-integrated luminosities of
$0.2 - 0.4$~fb$^{-1}$.  The recorded time-integrated luminosity for
Run~II is presently in excess of 1~fb$^{-1}$ and, at the time of this
writing, the Tevatron peak instantaneous luminosity record recently
exceeded $1.5 \times 10^{32}$~cm$^{-2}$s$^{-1}$.

At present datataking efficiencies of 85$-$90\%, and under the current
Tevatron accelerator performance, a minimum of 2~fb$^{-1}$ are
expected by the end of 2006 and 6~fb$^{-1}$ by the end of 2008, at
least two doublings over the next four years.  When considered beside 
both the data already collected
and these conservative luminosity projections, the data that have been
analysed to date represent less than one tenth of the Tevatron
program's baseline reach.  Factoring in planned upgrades to the
Tevatron accelerator complex, including electron cooling, three
integrated luminosity doublings are expected, {\it i.e.}, 4~fb$^{-1}$
by 2007 and 8~fb$^{-1}$ by 2009.  The following discusses selected
physics projections for Run~II of the Tevatron.

In the broad range of $B$ physics measurements possible at, and unique
to, the Tevatron, the study of $B_s$ mixing will contribute unique
testing of the flavour sector in the Standard Model.  When taking into
account improvements in existing analysis procedures, including kaon
tagging, additional channels, trigger adjustments, and a 20\%
improvement in vertex resolution, the Tevatron is expected to extend
sensitivity from a 95\% C.L. exclusion with 2~fb$^{-1}$, to 3$\sigma$
evidence with 4~fb$^{-1}$, to 5$\sigma$ discovery with 8~fb$^{-1}$.
Refer to Fig.~\ref{fig:Bs_mixing_projection.eps}.  The absence of a
discovery of $B_s$ mixing in 8~fb$^{-1}$ would represent a striking
contravention of the Standard Model, {\it i.e.}, new physics.

\begin{figure}
\begin{center}
%\leavemode
\epsfxsize=2.5in
\epsffile{Bs_mixing_projection.eps}
\end{center}
\caption{The Tevatron $B_s$ mixing 5$\sigma$ discovery projection,
as a function of delivered luminosity per experiment.}
\label{fig:Bs_mixing_projection.eps}
\end{figure}

In the intense international search for the Standard Model Higgs
boson, the Tevatron is anticipated to play a vital role.  With samples
of 4~fb$^{-1}$, potentially attainable before the end of the period of
LHC commissioning, 3$\sigma$ evidence for Higgs masses greater than
the LEP limit (114.4 GeV at 95\% C.L.) will be possible.  With
8~fb$^{-1}$, the 3$\sigma$ evidence could be extended to Higgs masses
as high as 130~GeV.  This mass region, favoured by electroweak data
and supersymmetry, represents a particular challenge to the LHC
experiments, which, to explore it, would need ideal and well
understood detector performance, more than 10~fb$^{-1}$ of data per
experiment, and effective rejection of high backgrounds.  If the SM
Higgs boson were to lie in this favoured region, these challenges, in
addition to the fact that the Tevatron and LHC are sensitive to
different Higgs decay modes, underscore the critical importance of the
development of a multi-fb$^{-1}$ CDF-II physics programme.  The
shortened time-to-discovery that such a complementarity between the
LHC and Tevatron programmes will promote will also serve to inform
urgent planning for the International Linear Collider.

Supersymmetric mass scales could be accessible to the Tevatron if SUSY
is the mechanism for maintaining radiative stability at both the
electroweak and GUT energy scales.  Using the most straightforward
model-independent signature of jets and missing transverse energy, the
mass discovery reach for gluinos and squarks increases by over 20~GeV
for an increase in time-integrated luminosity from 2~fb$^{-1}$ to
8~fb$^{-1}$.  In the case of gaugino-partner (chargino and neutralino)
production with the distinctive decay signature of no jets, three
charged leptons, and missing transverse energy, the gain from
luminosity is even greater: 30~GeV for chargino masses when increasing
from 2~fb$^{-1}$ to 4~fb$^{-1}$, and an additional 30~GeV from
4~fb$^{-1}$ to 8~fb$^{-1}$.  It has been noted that these gains in
reach exceed those that were achievable by the energy increase
throughout the LEP2 program.

Run~II has already been able to exclude part of the light-mass regions
of MSSM Higgs boson predictions.  There exists the exciting prospect,
however, of a discovery by the Tevatron of MSSM Higgs bosons in the
large $\tan\beta$ region.  For $\tan\beta = 60$, the $3\sigma$ reach
is expected to range up to masses of 180~GeV for 1~fb$^{-1}$ and
240~GeV for 8~fb$^{-1}$.

Profound constraints placed on descriptions of electroweak symmetry
breaking are driven by the experimentally challenging reduction of
measurement uncertainties on the masses of the top quark and $W$
boson.  As the integrated luminosity increases from 2~fb$^{-1}$ to
4~fb$^{-1}$, for example, the anticipated uncertainties on the masses
are expected to improve by $\sim 20$\%; refer to
Fig.~\ref{fig:top_W_singletop}.  Once direct evidence for a Higgs or
similar mechanism begins to be revealed, these precision measurements
will be key to decisive tests of the theory.

\begin{figure}
\begin{center}
\epsfig{figure=Mtop_total.eps,height=1.50in}
\hskip 0.0in
\epsfig{figure=mw_projection.eps,height=1.50in}
\hskip 0.0in
\epsfig{figure=singleTopProjection.eps,height=1.50in}
\end{center}
\caption{ {\bf [left]} Total uncertainty on $m_{\rm top}$ for CDF in
  the lepton-plus-jets channel alone; the reduction with luminosity is
  driven by the statistical nature of the jet-energy-scale (JES)
  uncertainty.  {\bf [centre]} Extrapolation of the scaling of the
  $m_W$ uncertainty with increasing luminosity.  {\bf [right]}
  Projected sensitivity for single-top production for the $s$ and $t$
  channels combined, not taking into account systematic
  uncertainties.}
\label{fig:top_W_singletop}
\end{figure}

Clearly, some measurements made using the anticipated Tevatron Run~II
data will later be repeated at the LHC with enhanced statistics.  We
note, however, that in some cases the two accelerators probe different
regions of initial-state dynamics, by virtue of the different beam
energies and particles.  In addition to the complementary low-mass
Higgs reaches mentioned above, electroweak single-top production at
the two accelerators is expected to have differing contributions to
the $s$ and $t$ channels, each of which have different sensitivities
to new physics processes.  Single-top production may first be observed
($5\sigma$) at the Tevatron using a time-integrated luminosity of $5 -
7$~fb$^{-1}$; refer to the projection depicted in
Fig.~\ref{fig:top_W_singletop}.  In a similar spirit, and to enhance
the chances of discovering physics beyond the SM, efforts to
understand the relative strengths of different $b\bar{b}$ and
$t\bar{t}$ QCD hadroproduction mechanisms at the Tevatron are needed
for comparisons with similar measurements to be made at the LHC, where
the same production mechanisms are anticipated to contribute with
markedly different weights.

The CDF physics program has begun productively in both an
energy-frontier and precision capacity, following a significant
investment of scientific, technical, and financial resources.
Following through on this investment, the multi-fb$^{-1}$ Tevatron
Run~II plan will cover an exciting period at the discovery and
sensitivity frontiers in a manner that is both unique and
complementary to LHC turn-on and commissioning.

