Presentation on theme: "PQ-invariant multi-singlet NMSSM with anomalous U(1) gauge symmetry Kiwoon Choi The IBS Center for Theoretical Physics of the Universe KIAS-NCTS Workshop."— Presentation transcript:
PQ-invariant multi-singlet NMSSM with anomalous U(1) gauge symmetry Kiwoon Choi The IBS Center for Theoretical Physics of the Universe KIAS-NCTS Workshop 2014
Outline 1. Introduction and motivation 2. Singlet extension of the MSSM with U(1) PQ originating from an anomalous U(1) gauge symmetry: * 126 GeV Higgs boson with a minimal fine tuning * Generation of an intermediate PQ scale: * Natural solution to - SUSY flavor problem - μ problem - Cosmological moduli problem 3. A specific form of the minimal model with two singlets 4. Conclusion
Introduction and motivation The Standard Model (SM) of particle physics is now completed, however it is certain that the SM is not the final story, but merely a low energy effective theory of certain form of more fundamental theory. Empirical evidences for physics beyond the SM (BSM physics): * Non-baryonic dark matter * Matter-antimatter asymmetry in our Universe * Neutrino masses * Inflation in the early Universe Incomplete or unnatural features of the SM: * Lack of the unification & quantum gravity * Fine-tuning problems: - Gauge hierarchy problem: - Strong CP problem:
What to do? * Search for the rare signals of the SM particles, reflecting the next BSM scale: Precision measurement of the Higgs and EW gauge bosons: EDM and (g-2): Flavor changing processes: * Search for new particles This requires a guideline, and at the moment, the best motivated new particles are those associated with the solutions of the fine tuning problems of the SM: Gauge hierarchy problem and Strong CP problem SUSY particles (including the WIMP DM) and axion DM
SUSY as a solution to the gauge hierarchy problem Supersymmetry SUSY particles Fermi-Bose cancellation in the Higgs boson self energy: + m SUSY = SUSY particle masses, particularly m stop and m gluino With SUSY, the Higgs boson mass can be as light as m SUSY without a fine-tuning of UV physics.
Implications of the recent LHC results for SUSY * Discovery of the SM-like 126 GeV Higgs boson * No sign of SUSY yet
Axion search experiments are approaching to this region for axion DM. The new Center for Axion and Precision Physics (CAPP) in the Institute for Basic Science (IBS) of Korea will join soon this game searching for the axion DM!
ADMX (Axion Dark Matter eXperiment) vs CAPP (Y. Semertzidis) Current plan B-field High-Q B-field DM axion mass
* Low scale SUSY and the QCD axion are still the most compelling & interesting candidates for BSM physics. * They are introduced to understand some of the highly nontrivial hierarchical structures of the SM parameters: Scale hierarchy: (Gauge hierarchy problem) CP-angle hierarchy: (Strong CP problem) * They shed a light also on different questions such as the dark matter & unification. * They provide concrete predictions which can be tested experimentally in the foreseeable future. * There are many virtues of having them together!
Difficulties of low scale SUSY: * μ-problem * SUSY flavor problem * Cosmological moduli problem Questions about the axion solution to the strong CP problem: * Origin of U(1) PQ whose explicit breaking other than the QCD anomaly is extremely suppressed: Axion potential induced by generic high scale dynamics: * Origin of the intermediate PQ scale 10 9 GeV < v PQ < GeV Having SUSY together with U(1) PQ that originates from an anomalous U(1) gauge symmetry, all of these problems can be solved in a natural manner.
* Origin of U(1) PQ : Anomalous U(1) A gauge symmetry is a nearly generic feature of realistic string compactification, and it is broken often by the Stuckelberg mechanism: -Stuckelberg mechanism: Gauge boson gains a heavy mass without breaking the global part of U(1) A. U(1) PQ = Unbroken global part of U(1) A * Origin of the intermediate PQ-breaking scale: Spontaneous PQ-breaking by a balance between SUSY-breaking effect (by the D-term of U(1) A ) and Planck-scale suppressed effect: Murayama, Suzuki, Yanagida ( )
* Flavor-degenerate sfermions masses SUSY breaking in models with anomalous U(1) A gauge symmetry: KC, Jeong, Okumura, Yamaguchi (Flavor-degenerate D A always dominates over the potentially dangerous flavor-non-degenerate gravity mediation.) There can be additional gauge-mediated SUSY breaking induced by the PQ-breaking sector, which is comparable to D A. Sfermion masses are determined mostly by the flavor-degenerate U(1) A D-term and gauge mediation. and
Among those two models, the one with is particularly interesting as it allows a limit where the singlet sector is parametrically lighter than the MSSM sector without causing any further fine-tuning: For instance, we can consider a limit which has a variety of interesting implications for the Higgs and DM physics, as well as the collider signatures of the model. KC, S.H. Im, M.S. Seo (in preparation)
Conclusion 1. Low scale SUSY and the QCD axion are still the most compelling candidate for BSM physics : -Solve the gauge hierarchy problem & the strong CP problem -Provide attractive DM candidates: axions and/or neutralinos -Fit nicely with the unification and also with string theory -Phenomenological consequences which are within the reach of experimental tests in the foreseeable future 2. Singlet-extension of the MSSM at the TeV scale is well motivated by the observed Higgs boson mass m higgs =126 GeV and a request for the minimal fine-tuning.