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Supersymmetric particles
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Title: Why have supersymmetric particles not been observed?
Authors: Fuminobu Takahashi, Tsutomu T. Yanagida

If low-energy supersymmetry is the solution to the hierarchy problem, it is a puzzle why supersymmetric particles have not been observed experimentally to date. We show that supersymmetric particles in the TeV region can be explained if the fundamental cut-off scale of the theory is smaller than the 4-dimensional Planck scale and if thermal leptogenesis is the source of the observed baryon asymmetry. The supersymmetric particles such as sfermions and gauginos are predicted to be in the TeV region, while the gravitino is the LSP with mass of O(100)GeV and is a good candidate for dark matter. We argue that the gravitino dark mater is the major reason for the low-energy supersymmetry at the TeV scale. Interestingly, the cosmological moduli problem can be solved in the theory with the low cut-off scale.

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RE: Supersymmetry
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Title: Dark Matter, Baryon Asymmetry, and Spontaneous B and L Breaking
Authors: Timothy R. Dulaney (1), Pavel Fileviez Perez (2), Mark B. Wise (1) ((1) Caltech, (2) Wisconsin U., Madison)
(Version v3)

We investigate the dark matter and the cosmological baryon asymmetry in a simple theory where baryon (B) and lepton (L) number are local gauge symmetries that are spontaneously broken. In this model, the cold dark matter candidate is the lightest new field with baryon number and its stability is an automatic consequence of the gauge symmetry. Dark matter annihilation is either through a leptophobic gauge boson whose mass must be below a TeV or through the Higgs boson. Since the leptophobic gauge boson has to be below the TeV scale one finds that in the first scenario there is a lower bound on the elastic cross section of about 5x10-46 cm2. Even though baryon number is gauged and not spontaneously broken until the weak scale, a cosmologically acceptable baryon excess is possible. In particular, if L is broken at a high scale the baryon excess can be generated by right-handed neutrino decays. There is tension between achieving both the measured baryon excess and the dark matter density.

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Humans have used symmetrical patterns for thousands of years in both functional and decorative ways. Now, a new book by three mathematicians offers both math experts and enthusiasts a new way to understand symmetry and a fresh way to see the world.
In The Symmetries of Things, eminent Princeton mathematician John H. Conway teams up with Chaim Goodman-Strauss of the University of Arkansas and Heidi Burgiel of Bridgewater State College to present a comprehensive mathematical theory of symmetry in a richly illustrated volume. The book is designed to speak to those with an interest in math, artists, working mathematicians and researchers.

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Title: Supersymmetry on the Rocks
Authors: Markus Ahlers (DESY Hamburg)

In R-parity conserving supersymmetric (SUSY) models the lightest SUSY particle (LSP) is stable and a candidate for dark matter. Depending on the coupling and mass of this particle the life time of the next-to-lightest SUSY particle (NLSP) may be large compared to experimental time scales. In particular, if the NLSP is a charged particle and its decay length is of the order of the Earth's diameter Cherenkov telescopes might observe parallel muon-like tracks of NLSP pairs produced in neutrino-nucleon interactions in the Earth's interior. We have investigated two SUSY scenarios with a long-lived stau NLSP and a gravitino LSP in view of the observability at the IceCube detector.

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Supersymmetry breaking
Authors: Yael Shadmi

These lectures provide a simple introduction to supersymmetry breaking. After presenting the basics of the subject and illustrating them in tree-level examples, we discuss dynamical supersymmetry breaking, emphasizing the role of holomorphy and symmetries in restricting dynamically-generated superpotentials. We then turn to mechanisms for generating the MSSM supersymmetry-breaking terms, including "gravity mediation", gauge mediation, and anomaly mediation. We clarify some confusions regarding the decoupling of heavy fields in general and D-terms in particular in models of anomaly-mediation.

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