Impact of R-Parity Violation on Supersymmetry Searches at the Tevatron

We evaluate cross sections for \eslt, 1$\ell$ and various dilepton and multilepton event topologies that result from the simultaneous production of all sparticles at the Tevatron collider, both within the minimal model framework as well as in two different $R$-parity violating scenarios. Our analysis assumes that these $R$-violating couplings are small, and that their sole effect is to cause the lightest supersymmetric particle to decay inside the detector. We reassess future strategies for sparticle searches at the Tevatron, and quantify by how much the various signals for supersymmetry could differ from their minimal model expectations, if $R$-parity is not conserved due to either baryon number or lepton number violating operators. We also evaluate the Tevatron reach in $m_{\tg}$ for the various models, and find that rate-limited multilepton signals ultimately provide the largest reach for both $R$-parity conserving and $R$-parity violating cases.Comment: preprint nos. FSU-HEP-941001, UR-1387, ER-40685-836 and UH-511-807-94, 13 pages (REVTEX) plus 3 uuencoded figures attache

SUPERSYMMETRY REACH OF AN UPGRADED TEVATRON COLLIDER

We examine the capability of a $\sqrt{s}=2$ TeV Tevatron $p\bar p$ collider to discover supersymmetry, given a luminosity upgrade to amass $25\ fb^{-1}$ of data. We compare with the corresponding reach of the Tevatron Main Injector ($1\ fb^{-1}$ of data). Working within the framework of minimal supergravity with gauge coupling unification and radiative electroweak symmetry breaking, we first calculate the regions of parameter space accessible via the clean trilepton signal from \tw_1\tz_2\to 3\ell +\eslt production, with detailed event generation of both signal and major physics backgrounds. The trilepton signal can allow equivalent gluino masses of up to $m_{\tg}\sim 600-700$ GeV to be probed if $m_0$ is small. If $m_0$ is large, then $m_{\tg}\sim 500$ GeV can be probed for $\mu 0$ and large values of $m_0$, the rate for \tz_2\to\tz_1\ell\bar{\ell} is suppressed by interference effects, and there is {\it no} reach in this channel. We also examine regions where the signal from \tw_1\overline{\tw_1}\to \ell\bar{\ell}+\eslt is detectable. Although this signal is background limited, it is observable in some regions where the clean trilepton signal is too small. Finally, the signal \tw_1\tz_2\to jets+\ell\bar{\ell} +\eslt can confirm the clean trilepton signal in a substantial subset of the parameter space where the trilepton signal can be seen. We note that although the clean trilepton signal may allow Tevatron experiments to identify signals in regions of parameter space beyond the reach of LEP II, the dilepton channels generally probe much the same region as LEP II.Comment: 19 page REVTEX file; a uuencoded PS file with PS figures is available via anonymous ftp at ftp://hep.fsu.edu/preprints/baer/FSUHEP950301.u

SIGNALS FOR MINIMAL SUPERGRAVITY AT THE CERN LARGE HADRON COLLIDER: MULTI-JET PLUS MISSING ENERGY CHANNEL,

We use ISAJET to perform a detailed study of the missing transverse energy \eslt plus multi-jet signal expected from superparticle production at the CERN LHC. Our analysis is performed within the framework of the minimal supergravity model with gauge coupling unification and radiative electroweak symmetry breaking. We delineate the region of parameter space where the \eslt supersymmetry signal should be observable at the LHC and compare it to the regions explorable via searches for sleptons and for chargino/neutralino production. We confirm that, given a data sample of 10~\fb^{-1}, $m_{\tg}\sim 1300$ GeV can be explored if m_{\tq}\gg m_{\tg}, while $m_{\tg}\sim 2000$ GeV can be probed if m_{\tq}\simeq m_{\tg}. We further examine what information can be gleaned from scrutinizing this event sample. For instance, the multi-jet multiplicity yields information on whether squark production makes a significant contribution to the observed \eslt sample. Furthermore, reconstructing hemispheric masses may yield a measure of $m_{\tg}$ to $\sim 15-25\%$. Finally, for favourable ranges of parameters, by reconstructing masses of tagged $b\bar{b}$ jet pairs, it may be possible to detect Higgs bosons produced via sparticle cascade decay chains.Comment: 22 pages (REVTEX); a PS text file (etmiss.ps) and 12 figures (etlhc.uu or etlhc.ps) can be obtained via anonymous ftp at ftp://hep.fsu.edu/anonymous.bae

Multiple Parton Emission Effects in Next-to-Leading Order Direct Photon Production

A recent global analysis of direct photon production at hadron collider and fixed target experiments has noted a disturbing trend of disagreement between next-to-leading-order (NLO) calculations and data. The conjecture has been made that the discrepancy is due to explicit multiple parton emission effects which are not accounted for in the theoretical calculations. We investigate this problem by merging a NLO calculation of direct photon production with extra multiple parton emissions via the parton shower (PS) algorithm. Our calculation maintains the integrity of the underlying NLO calculation while avoiding ambiguities due to double counting of multiple parton emissions. We find that the NLO+PS calculation can account for much of the theory/CDF data discrepancy at $\sqrt{s}=1.8$ TeV. It can also account for much of the theory/UA2 discrepancy if a very large virtuality is assumed to initiate the initial state parton shower. For lower energy data sets ({\it e.g.} $\sqrt{s}< 63$ GeV), NLO+PS calculations alone cannot account for the data/theory discrepancy, so that some additional non-perturbative $k_T$ smearing is needed.Comment: 9 page REVTEX file with 3 figures; a PS version with figures is available from ftp://hep.fsu.edu/preprints/baer/FSUHEP951229.u

Signals for the Minimal Gauge-mediated Supersymmetry Breaking Model at the Fermilab Tevatron Collider

We investigate the experimental implications of the minimal gauge-mediated low energy supersymmetry breaking (GMLESB) model for Fermilab Tevatron collider experiments. We map out the regions of parameter space of this model that have already been excluded by collider searches and by limits on $b\to s\gamma$. We use ISAJET to compute the cross sections for a variety of topological signatures which include photons in assocation with multiple leptons, jets and missing transverse energy. The reach in the parameter $\Lambda$, which fixes the scale of sparticle masses, is estimated to be $\sim 60$, 100 and 135 TeV for Tevatron integrated luminosities of 0.1, 2 and 25 fb$^{-1}$, respectively. The largest signals occur in photon(s) plus lepton(s) plus multi-jet channels; jet-free channels containing just photons plus leptons occur at much smaller rates, at least within this minimal framework.Comment: 18 page REVTEX file plus 11 PS figure

Simultaneous Search for Two Higgs Bosons of Minimal Supersymmetry at the LHC

The prospects of detecting the CP-odd Higgs pseudoscalar ($A$) in the minimal supersymmetric model via its decay into a $Z$ boson and the lighter CP-even Higgs scalar ($h$) at the CERN Large Hadron Collider are investigated. The final state of $Z \to l^+l^-$ and $h \to b\bar{b}$, may provide a promising way to simultaneously detect the $A$ and the $h$. The compact muon solenoid detector performance is adopted for a realistic study of observability. In this discovery channel, the masses of the $h$ and the $A$ can be reconstructed. The impact of supersymmetric decay modes is considered.Comment: 17 pages, REVTEX, 6 figure

The twilight of the Liberal Social Contract? On the Reception of Rawlsian Political Liberalism

This chapter discusses the Rawlsian project of public reason, or public justification-based 'political' liberalism, and its reception. After a brief philosophical rather than philological reconstruction of the project, the chapter revolves around a distinction between idealist and realist responses to it. Focusing on political liberalism’s critical reception illuminates an overarching question: was Rawls’s revival of a contractualist approach to liberal legitimacy a fruitful move for liberalism and/or the social contract tradition? The last section contains a largely negative answer to that question. Nonetheless the chapter's conclusion shows that the research programme of political liberalism provided and continues to provide illuminating insights into the limitations of liberal contractualism, especially under conditions of persistent and radical diversity. The programme is, however, less receptive to challenges to do with the relative decline of the power of modern states

Constitutivism

A brief explanation and overview of constitutivism

Signals for Minimal Supergravity at the CERN Large Hadron Collider II: Multilepton Channels

We use ISAJET to perform a detailed study of the multilepton signals expected from cascade decays of supersymmetric particle produced at the CERN LHC. Our analysis is performed within the framework of the minimal supergravity model with gauge coupling unification and radiative electroweak symmetry breaking. We delineate the regions of parameter space where jets plus missing energy plus 1, 2 (opposite sign and same-sign dileptons), and 3 isolated lepton events should be visible above standard model backgrounds. We find that if any \eslt signal at the LHC is to be attributed to gluino and/or squark production, and if m_{\tg} \alt 1~TeV, then several of these signals must be simultaneously observable. Furthermore, assuming 10\,\fb^{-1} of integrated luminosity, we find that the reach for supersymmetry in the 1\ell + \jets +\eslt channel extends to $m_{\tg}\sim 2300\ (1600)$ GeV for m_{\tq}\sim m_{\tg} (m_{\tq} \sim 1.5m_{\tg}), and exceeds the corresponding reach in the 0\ell+\eslt channel. We show that measurements of the various topological cross sections, jet and $B$-hadron multiplicities in these events, together with the charge asymmetry for single lepton and same-sign dilepton events, and flavor asymmetry for opposite sign dilepton events, serve to narrow the allowed range of underlying SUGRA parameter values. We also delineate parameter regions where signals with clean isolated dilepton (from slepton production) and trilepton events (from chargino/neutralino production) are visible at the LHC, and examine the extent to which these signals can be separated from other SUSY sources.Comment: 35 page REVTEX file; 18 uuencoded EPS figures are included. Full resolution ones available via anonymous ftp at ftp://hep.fsu.edu/preprints/baer/xxx.uu; a complete PS file of text and figures is also available as FSUHEP951215.p