Searching for Supersymmetry: A Minireview

After a lightning review of current bounds on the masses of supersymmetric particles, we describe strategies that may be helpful for extracting signals from the production of squarks, gluinos or top squarks, and from associated chargino-neutralino production at the Tevatron. We then briefly review SUSY signals at hadron and $e^+e^-$ supercolliders. We discuss how various SUSY signals may be correlated within the supergravity framework and indicate the sense in which $e^+e^-$ and hadron colliders may be complementary. **Presented at the Eighth DPF Meeting, Albuquerque, NM, August, 1994**Comment: 8 pages, UH-511-794-9

Developments in Supersymmetry Phenomenology

We survey strategies generally employed for SUSY discovery at colliders and then discuss how these may have to be altered for SUSY searches at the Tevatron if $\tan\beta$ is large. We also discuss the reach of the Tevatron and the LHC in gauge-mediated SUSY breaking scenarios, assuming that the NLSP decays into photons. Finally, we briefly recapitulate measurements (which serve to guide us to the underlying theory) that might be possible at future colliders if supersymmetry is discovered.Comment: 9 pages, 3 figures, uses psfig.sty, sprocl.sty, Talk presented at PASCOS-98, March 199

Looking Beyond the Standard Model

Within the framework of the Standard Model, the scale of electroweak symmetry breaking is unstable to radiative corrections. We discuss two broad classes of models of new physics (one with a strongly interacting and the other with a perturbatively coupled electroweak symmetry breaking sector) in which this stability is restored. After reviewing experimental constraints on these, we discuss the implications of these types of models for experiments, both at currently operating colliders as well as the next generation of colliders under consideration for construction. Other extensions of the Standard Model are briefly alluded to.Comment: UH-511-803-94, 25 pages, 4 figures (not appended but available on request from the author), invited talk, presented at the Physics in Collision Conference, Tallahassee, June 199

Supersymmetry: Where it is and how to find it

We present a pedagogical, but by no means complete, review of weak scale supersymmetry phenomenology. After a general introduction to the new particles that must be present in any supersymmetric framework, we describe how to write down their interactions with one another as well as with the particles of the Standard Model. We then elucidate the assumptions underlying the Minimal Supersymmetric Model as well as the more restrictive minimal supergravity GUT model with the radiative breaking of electroweak symmetry. These models serve to guide our thinking about the implications of supersymmetry for experiments. To facilitate our study of signatures of supersymmetric particles at high energy colliders, we describe the decay patterns of sparticles as well as their production mechanisms in $e^+e^-$ and hadron-hadron collisions. We then discuss how sparticles may be searched for in on-going experiments at the Tevatron and at LEP. We review phenomenological constraints on supersymmetric particle masses from non-observation of any signals in these experiments, and also briefly discuss constraints from low energy experiments and from cosmology. Next, we study new strategies by which supersymmetric particles may be searched for at supercolliders, and also what we can learn about their properties (masses, spins, couplings) in these experiments. A determination of sparticle properties, we will see, may provide us with clues about the nature of physics at the ultra-high scale. After a brief discussion of possible extensions of the minimal framework and the implications for phenomenology, we conclude with our outlook for the future.Comment: Lectures presented at TASI'95; 58 pages LaTeX file. SPROCL.sty is needed to LaTeX file. Also needs psfig.sty. A postscript file of the whole paper including figures can be obtained via anonymous ftp at ftp://hep.fsu.edu/preprints/tata/preprint.p

Supersymmetry: Aspirations and Prospects

The realization in the early 1980s that weak scale supersymmetry stabilizes the Higgs sector of the spectacularly successful Standard Model led several authors to explore whether low energy supersymmetry could play a role in particle physics. Among these were Richard Arnowitt, Ali Chamseddine and Pran Nath who constructed a viable {\em locally} supersymmetric Grand Unified Theory (GUT), laying down the foundation for supergravity GUT models of particle physics. Supergravity models continue to be explored as one of the most promising extensions of the Standard Model. After a quick overview of some of the issues and aspirations of early researchers working to bring supersymmetry into the mainstream of particle physics, we re-examine early arguments that seemed to imply that superpartners would be revealed in experiments at LEP2 or at the Tevatron. Our purpose is to assess whether the absence of any superpartners in searches at LHC8 presents a crisis for supersymmetry. Toward this end, we re-evaluate fine-tuning arguments that lead to upper bounds on (some) superpartner masses. We conclude that phenomenologically viable superpartner spectra that could arise within a high scale model tuned no worse than a few percent are perfectly possible. While no viable underlying model of particle physics that leads to such spectra has yet emerged, we show that the (supergravity-based) Radiatively-driven Natural Supersymmetry (RNS) framework serves as a surrogate for a phenomenological analysis of an underlying theory with modest fine-tuning. We outline the phenomenological implications of this framework, with emphasis on those LHC and electron-positron collider signatures that might point to the underlying natural origin of gauge and Higgs boson masses. We conclude that the supergravity GUT paradigm laid down in 1982 by Arnowitt, Chamseddine and Nath, and others, remains a vibrant possibility.Comment: Contributed to the Proceedings of the Richard Arnowitt Memorial Symposium; 29 pages with 5 figures. arXiv admin note: text overlap with arXiv:1404.138

Recent Developments in supersymmetry Search Strategies

After a quick review of the framework for phenomenological analyses of supersymmetry, we summarize current limits on supersymmetric particle masses and discuss strategies for their searches at the Fermilab Tevatron and the LHC. We also discuss the sense in which such searches as well as those that may be carried out at LEP complement one another. Finally, we touch upon the prospects for more ambitious measurements such as those of sparticle masses and couplings. Such measurements could (a) help pin down model parameters, (b) perhaps, serve to test our ideas of physics at very high energy, and (c) provide the most direct test of supersymmetry.Comment: Talk presented at the 11th Dep't of Atomic Energy Symposium, Visvabharati University, Santiniketan, India. 19 pages. World_sci.sty attached after Latex file; Figures may be obtained by regular mail or fax from the Author

Supersymmetry, Naturalness, and Light Higgsinos

We compare and contrast three different sensitivity measures, $\Delta_{EW}^{-1}$, $\Delta_{HS}^{-1}$ and $\Delta_{BG}^{-1}$ that have been used in discussions of fine-tuning. We argue that though not a fine-tuning measure, $\Delta_{EW}$, which is essentially determined by the particle spectrum, is important because $\Delta_{EW}^{-1}$ quantifies the minimum fine-tuning present in any theory with a specified spectrum. We emphasize the critical role of incorporating correlations between various model parameters in discussions of fine-tuning. We provide toy examples to show that if we can find high scale theories with specific correlations amongst parameters, the value of the traditional fine-tuning measure $\Delta_{BG}^{-1}$ (which differs significantly from $\Delta_{HS}^{-1}$ only when these correlations are important) would be close to $\Delta_{EW}^{-1}$. We then set up the radiatively driven natural SUSY framework that we advocate for phenomenological analyses of natural models of supersymmetry, and review the implications of naturalness for LHC and ILC searches for SUSY as well as for searches for SUSY dark matter.Comment: 23 pages, 4 figures, Invited contribution to the Volume Commemorating C.V.Raman's 125th Birth Anniversary; v2: added footnote 7 and updated references, published version; v3: The cross sections for the pair production of electroweak-inos shown in Fig.2 were too high by a factor 2. The error is confined to just this figure, and does not affect any other results in the pape

Same-sign Higgsino Production at the CERN LHC: How Not to Hunt for Natural Supersymmetry

We examine the prospects for detecting light charged higgsinos that are expected to be a necessary feature of natural SUSY models via $pp\to {\widetilde W}^\pm{\widetilde W}_1^\pm jj+X$ processes arising dominantly from $W^\pm W^\pm$ fusion at LHC13. The signal will be a pair of same-sign leptons ($e$ or $\mu$) in events with two relatively forward, hemispherically-separated jets with a large rapidity gap. We find that even though the higgsinos have a full-strength $SU(2)$ gauge couplings to $W$-bosons, the LHC13 cross section for the production of same sign higgsino pairs is smaller than 0.02 fb over most of the interesting range of natural SUSY parameters, even before leptonic branching fractions of the chargino are included. This cross section is strongly suppressed because the two neutral Majorana higgsinos can be combined into a single Dirac neutralino if the bino and the winos are much heavier than the higgsinos, as is the case in natural SUSY models: in this limit, higgsino couplings to $W$-bosons exhibit an emergent (approximate) $U(1)_{\rm ino}$ global symmetry that suppresses same sign higgsino production by vector boson fusion. We conclude that this channel is not a viable way to search for natural SUSY even at the high luminosity upgrade of the Large Hadron Collider.Comment: 11 pages, 4 figure

What Is Supersymmetry And How Do We Find It?

In these Lectures, we present a pedagogical introduction to weak scale supersymmetry phenomenology. A basic understanding of the Standard Model and of the ideas behind Grand Unification, but no prior knowledge of supersymmetry, is assumed. Topics covered include: What is supersymmetry and why do we bother with it? Working with a supersymmetric theory: A toy example Construction of supersymmetric Lagrangians The Minimal Supersymmetric Model The mSUGRA Model: A paradigm for SUSY phenomenology Decays of supersymmetric particles Production of supersymmetric particles at colliders Observational constraints on supersymmetry Supersymmetry searches at future colliders Constraining supersymmetry models at future colliders R-parity violation Gauge-mediated supersymmetry breakingComment: 89 pages, 6 figures, uses psfig.sty,SPROCL.STY, Lectures given at IX Jorge A. Swieca Summer School, Campos do Jordao, Brazil, February 199

Supersymmetry Phenomenology: A Microreview

We briefly review the current status and future prospects for supersymmetry searches at colliders, and discuss strategies by which further information about sparticle properties may be obtained at the LHC.Comment: 7 pages LaTeX file, no figures. Needs sprocl.sty which can be obtained from the server. Talk presented at 1995 EPS Conference, Brussels, Belgium. A postscript file of the paper can be obtained via anonymous ftp at ftp://hep.fsu.edu/preprints/tata/brussels.p