Toward Full LHC Coverage of Natural Supersymmetry

We argue that combining just a handful of searches for new physics at Run I of the LHC is sufficient to exclude most supersymmetric extensions of the Standard Model in which the gluino is kinematically accessible and the spectrum is natural. Such models typically give rise to significant MET, top quarks and/or high object multiplicity, and we show that having even one of these signatures generally results in stringent limits. We also identify, among models that lack these signatures, the few gaps in coverage remaining, and propose search strategies to close these gaps. Our results are general and independent of the details of the spectrum, assumptions about minimality, R-parity, etc. Our analysis strategy should remain applicable when the LHC moves to higher energy. Central to our argument are ATLAS and CMS searches for many jets and low MET, a proposed lepton + many jets search, an ATLAS search for 6-7 high-pT jets, and a reexamination of the control and signal regions of the CMS black hole search.Comment: 53 pages, 16 figures, journal versio

Search for New Particles at LEP

The latest preliminary results of the searches for Higgs bosons and Supersymmetric particles at LEP are reviewed. The results include the data-taking in 1999 up to center-of-mass energies of 196 GeV. The combination of the results from the four LEP experiments leads to a significant increase of the detection sensitivity. No indication of a signal has been observed. In the Standard Model (SM) a lower limit of 102.6 GeV on the mass of the Higgs boson is set at 95% CL. In extended models, stringent limits are also set on the HZZ coupling. Interpretations in the Minimal extension of the Supersymmetric Standard Model (MSSM) are given and the importance of general MSSM parameter scans is emphasized. In general scans, the limit on the mass of the lightest scalar Higgs boson is about 7 GeV lower in comparison with benchmark results. The data also constrains charged Higgs bosons of a general two-doublet model and Supersymmetric partners of the SM particles.Comment: 16 pages, 38 figure

Measuring the SUSY Breaking Scale at the LHC in the Slepton NLSP Scenario of GMSB Models

We report a study on the measurement of the SUSY breaking scale sqrt(F) in the framework of gauge-mediated supersymmetry breaking (GMSB) models at the LHC. The work is focused on the GMSB scenario where a stau is the next-to-lightest SUSY particle (NLSP) and decays into a gravitino with lifetime c*tau_NLSP in the range 0.5 m to 1 km. We study the identification of long-lived sleptons using the momentum and time of flight measurements in the muon chambers of the ATLAS experiment. A realistic evaluation of the statistical and systematic uncertainties on the measurement of the slepton mass and lifetime is performed, based on a detailed simulation of the detector response. Accessible range and precision on sqrt(F) achievable with a counting method are assessed. Many features of our analysis can be extended to the study of different theoretical frameworks with similar signatures at the LHC.Comment: 28 pages, 12 figures (18 eps files). Revised version v2(published in JHEP): Some important corrections and additions to v

Phenomenology of Gluino Searches at the Tevatron

Present data indicates that the gluino (if it exists) must be heavier than about 95~GeV. During the next few years as the Tevatron integrated luminosity increases, gluino searches will be able to probe the mass range between 100 and 200~GeV. For masses in this range, a variety of gluino decay modes can provide viable signatures for gluino detection. Apart from the classic missing transverse energy signal, the detection of high transverse momentum like-sign dileptons may be the cleanest signature for gluino production. Other signatures such as the production of a hard photon in the gluino cascade decay may also play an important role in confirming the supersymmetric origin of events originating from gluino production and decay.Comment: 17 pages, PHYZZX format (with Ray Cowan's TABLES.TEX macros), invited talk presented at the SUSY-93 Workshop, Northeastern University, Boston, MA, 29 March--1 April 199

Long-lived staus from strong production in a simplified model approach

We study the phenomenology of a supersymmetric scenario where the next-to-lightest superparticle is the lighter stau and long-lived due to a very weakly coupled lightest superparticle, such as the gravitino. We investigate the LHC sensitivity and its dependence on the superparticle spectrum with an emphasis on strong production and decay. We do not assume any high-scale model for SUSY breaking but work along the lines of simplified models. Devising cuts that yield a large detection efficiency in the whole parameter space, we determine the LHC's discovery and exclusion potential. This allows us to derive robust limits on m_stau, m_gluino, a common m_squark, and m_stop1. We briefly discuss the prospects for observing stopped staus.Comment: 25 pages + references, 27 eps figures; v3: Matches journal version, typo in table 1 correcte

The same-sign top signature of R-parity violation

Baryonic R-parity violation could explain why low-scale supersymmetry has not yet been discovered at colliders: sparticles would be hidden in the intense hadronic activity. However, if the known flavor structures are any guide, the largest baryon number violating couplings are those involving the top/stop, so a copious production of same-sign top-quark pairs is in principle possible. Such a signal, with its low irreducible background and efficient identification through same-sign dileptons, provides us with tell-tale signs of baryon number violating supersymmetry. Interestingly, this statement is mostly independent of the details of the supersymmetric mass spectrum. So, in this paper, after analyzing the sparticle decay chains and lifetimes, we formulate a simplified benchmark strategy that covers most supersymmetric scenarios. We then use this information to interpret the same-sign dilepton searches of CMS, draw approximate bounds on the gluino and squark masses, and extrapolate the reach of the future 14 TeV runs.Comment: 32 pages, 12 figures, 3 tables, 1 appendi

Long-lived heavy quarks : a review

We review the theoretical and experimental situation for long-lived heavy quarks, or bound states thereof, arising in simple extensions of the Standard Model. If these particles propagate large distances before their decay, they give rise to specific signatures requiring dedicated analysis methods. In particular, vector-like quarks with negligible couplings to the three known families could have eluded the past experimental searches. While most analyses assume prompt decays at the production vertex, novel heavy quarks might lead to signatures involving displaced vertices, new hadronic bound states, or decays happening outside of the detector acceptance. We perform reinterpretations of existing searches for short- and long-lived particles, and give suggestions on how to extend their reach to long-lived heavy quarks.Comment: 17 pages, 9 figures, 8 tables. Version accepted for publication in AHEP on Very Heavy Quarks at the LHC. Version 2: References added and last section update

Analysis of sonic boom measurements near shock wave extremities for flight near Mach 1.0 and for airplane accelerations

The analysis of the 14 low-altitude transonic flights showed that the prevailing meteorological consideration of the acoustic disturbances below the cutoff altitude during threshold Mach number flight has shown that a theoretical safe altitude appears to be valid over a wide range of meteorological conditions and provides a reasonable estimate of the airplane ground speed reduction to avoid sonic boom noise during threshold Mach number flight. Recent theoretical results for the acoustic pressure waves below the threshold Mach number caustic showed excellent agreement with observations near the caustic, but the predicted overpressure levels were significantly lower than those observed far from the caustic. The analysis of caustics produced by inadvertent low-magnitude accelerations during flight at Mach numbers slightly greater than the threshold Mach number showed that folds and associated caustics were produced by slight changes in the airplane ground speed. These caustic intensities ranged from 1 to 3 time the nominal steady, level flight intensity