Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magnifying the ATLAS Stealth Stop Splinter: Impact of Spin Correlations
  and Finite Widths   In this paper, we recast a "stealth stop" search in the notoriously difficult
region of the stop-neutralino Simplified Model parameter space for which
$m(\tilde{t}) - m(\tilde{\chi}) \simeq m_t$. The properties of the final state
are nearly identical for tops and stops, while the rate for stop pair
production is $\mathcal{O}(10\%)$ of that for $t\bar{t}$. Stop searches away
from this stealth region have left behind a "splinter" of open parameter space
when $m(\tilde{t}) \simeq m_t$. Removing this splinter requires surgical
precision: the ATLAS constraint on stop pair production reinterpreted here
treats the signal as a contaminant to the measurement of the top pair
production cross section using data from $\sqrt{s} = 7 \text{ TeV}$ and $8
\text{ TeV}$ in a correlated way to control for some systematic errors. ATLAS
fixed $m(\tilde{t}) \simeq m_t$ and $m(\tilde{\chi})= 1 \text{ GeV}$, implying
that a careful recasting of these results into the full $m(\tilde{t}) -
m(\tilde{\chi})$ plane is warranted. We find that the parameter space with
$m(\tilde{\chi})\lesssim 55 \text{ GeV}$ is excluded for $m(\tilde{t}) \simeq
m_t$ --- although this search does cover new parameter space, it is unable to
fully pull the splinter. Along the way, we review a variety of interesting
physical issues in detail: (i) when the two-body width is a good approximation;
(ii) what the impact on the total rate from taking the narrow width is a good
approximation; (iii) how the production rate is affected when the wrong widths
are used; (iv) what role the spin correlations play in the limits. In addition,
we provide a guide to using MadGraph for implementing the full production
including finite width and spin correlation effects, and we survey a variety of
pitfalls one might encounter.

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The categories of this paper are: gr-qc
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The categories of this paper are: alg-geom
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The categories of this paper are: dg-ga
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The categories of this paper are: solv-int
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The categories of this paper are: astro-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: chem-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: adap-org
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The categories of this paper are: acc-phys
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The categories of this paper are: nucl-ex
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The categories of this paper are: econ
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The categories of this paper are: chao-dyn
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The categories of this paper are: cs
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The categories of this paper are: nlin
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The categories of this paper are: atom-ph