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Dynamical (super) symmetry breaking

Description: Dynamical Symmetry Breaking (DSB) is a concept theoristsrely on very often in the discussions of strong dynamics, model building,and hierarchy problems. In this talk, I will discuss why this is such apermeating concept among theorists and how they are used in understandingphysics. I also briefly review recent progress in using dynamicalsymmetry breaking to construct models of supersymmetry breaking andfermion masses.
Date: October 3, 2000
Creator: Murayama, Hitoshi
Partner: UNT Libraries Government Documents Department

New inflation vs. chaotic inflation, higher degree potentials and the reconstruction program in light of WMAP3

Description: The cosmic microwave background power spectra are studied for different families of single field new and chaotic inflation models in the effective field theory approach to inflation. We implement a systematic expansion in 1/N(e), where N(e)~;;50 is the number of e-folds before the end of inflation. We study the dependence of the observables (n(s), r and dn(s)/dlnk) on the degree of the potential (2n) and confront them to the WMAP3 and large scale structure data: This shows in general that fourth degree potentials (n=2) provide the best fit to the data; the window of consistency with the WMAP3 and LSS data narrows for growing n. New inflation yields a good fit to the r and n(s) data in a wide range of field and parameter space. Small field inflation yields r<0.16 while large field inflation yields r>0.16 (for N(e)=50). All members of the new inflation family predict a small but negative running -4(n+1) x 10-4<=dn(s)/dlnk<=-2 x 10-4. (The values of r, n(s), dn(s)/dlnk for arbitrary N(e) follow by a simple rescaling from the N(e)=50 values.) A reconstruction program is carried out suggesting quite generally that for n(s) consistent with the WMAP3 and LSS data and r<0.1 the symmetry breaking scale for new inflation is |phi0|~;;10MPl while the field scale at Hubble crossing is lbar phi(c) rbar~;;M(Pl). The family of chaotic models features r>=0.16 (for N(e)=50) and only a restricted subset of chaotic models are consistent with the combined WMAP3 bounds on r, n(s), dn(s)/dlnk with a narrow window in field amplitude around |phi(c)|~;;15M(Pl). We conclude that a measurement of r<0.16 (for N(e)=50) distinctly rules out a large class of chaotic scenarios and favors small field new inflationary models. As a general consequence, new inflation emerges more favored than chaotic inflation.
Date: February 12, 2007
Creator: Ho, Chiu Man; Boyanovsky, D.; de Vega, H.J.; Ho, C.M. & Sanchez, N.G.
Partner: UNT Libraries Government Documents Department

Orbital-optimized opposite-spin scaled second order correlation: An economical method to improve the description of open-shell molecules

Description: Coupled cluster methods based on Brueckner orbitals are well-known to resolve the problems of symmetry-breaking and spin-contamination that are often associated with Hartree-Fock orbitals. However their computational cost is large enough to prevent application to large molecules. Here they present a simple approximation where the orbitals are optimized with the mean-field energy plus a correlation energy taken as the opposite-spin component of the second order many-body correlation energy, scaled by an empirically chosen parameter (recommended as 1.2 for general applications). This optimized 2nd order opposite spin (abbreviated as O2) method requires fourth order computation on each orbital iteration. O2 is shown to yield predictions of structure and frequencies for closed shell molecules that are very similar to scaled second order Moller-Plesset methods. However it yields substantial improvements for open shell molecules, where problems with spin-contamination and symmetry breaking are shown to be greatly reduced.
Date: January 1, 2007
Creator: Lochan, Rohini C. & Head-Gordon, Martin
Partner: UNT Libraries Government Documents Department

rSUGRA: Putting Nonuniversal Gaugino Masses on the (W)MAP

Description: In this talk, we investigate the relic density and direct detection prospects of rSUGRA, a simple paradigm for supersymmetry breaking that allows for nonuniversal gaugino masses. We present updated plots reflecting the latest cosmological measurements from WMAP.
Date: June 17, 2003
Creator: Birkedal-Hansen, Andreas
Partner: UNT Libraries Government Documents Department

Duality after supersymmetry breaking

Description: Starting with two supersymmetric dual theories, we imagine adding a chiral perturbation that breaks supersymmetry dynamically. At low energy we then get two theories with soft supersymmetry-breaking terms that are generated dynamically. With a canonical K{umlt a}hler potential, some of the scalars of the ``magnetic`` theory typically have negative mass-squared, and the vector-like symmetry is broken. Since for large supersymmetry breaking the ``electric`` theory becomes ordinary QCD, the two theories are then incompatible. For small supersymmetry breaking, if duality still holds, the magnetic theory analysis implies specific patterns of chiral symmetry breaking in supersymmetric QCD with small soft masses.
Date: May 1, 1998
Creator: Shadmi, Yael & Cheng, Hsin-Chia
Partner: UNT Libraries Government Documents Department

RG analysis of magnetic catalysis in dynamical symmetry breaking

Description: We perform the renormalization group analysis on the dynamical symmetry breaking under strong external magnetic field, studied recently by Gusynin, Miransky and Shovkovy. We find that any attractive four-Fermi interaction becomes strong in the low energy, thus leading to dynamical symmetry breaking. When the four-Fermi interaction is absent, the {beta}-function for the electromagnetic coupling vanishes in the leading order in 1/N. By solving the Schwinger-Dyson equation for the fermion propagator, we show that in 1/N expansion, for any electromagnetic coupling, dynamical symmetry breaking occurs due to the presence of Landau energy gap by the external magnetic field. 5 refs.
Date: May 1, 1996
Creator: Hong, Deog Ki & Kim, Youngman
Partner: UNT Libraries Government Documents Department

Electroweak Symmetry Breaking via UV Insensitive Anomaly Mediation

Description: Anomaly mediation solves the supersymmetric flavor and CP problems. This is because the superconformal anomaly dictates that supersymmetry breaking is transmitted through nearly flavor-blind infrared physics that is highly predictive and UV insensitive. Slepton mass squareds, however, are predicted to be negative. This can be solved by adding D-terms for U(1)_Y and U(1)_{B-L} while retaining the UV insensitivity. In this paper we consider electroweak symmetry breaking via UV insensitive anomaly mediation in several models. For the MSSM we find a stable vacuum when tanbeta< 1, but in this region the top Yukawa coupling blows up only slightly above the supersymmetry breaking scale. For the NMSSM, we find a stable electroweak breaking vacuum but with a chargino that is too light. Replacing the cubic singlet term in the NMSSM superpotential with a term linear in the singlet wefind a stable vacuum and viable spectrum. Most of the parameter region with correct vacua requires a large superpotential coupling, precisely what is expected in the"Fat Higgs'" model in which the superpotential is generated dynamically. We have therefore found the first viable UV complete, UV insensitive supersymmetry breaking model that solves the flavor and CP problems automatically: the Fat Higgs model with UV insensitive anomaly mediation. Moreover, the cosmological gravitino problem is naturally solved, opening up the possibility of realistic thermal leptogenesis.
Date: February 19, 2004
Creator: Kitano, Ryuichiro; Kribs, Graham D. & Murayama, Hitoshi
Partner: UNT Libraries Government Documents Department

Physics of Extra Dimensions Final Report

Description: We provide the final report for Csaba Csaki's OJI project on "Physics of extra dimensions". It includes the summary of results of higgsless electroweak symmetry breaking, gauge-higgs unification, AdS/QCD and holographic technicolor, and chiral lattice theories from warped extra dimensions.
Date: December 19, 2007
Creator: Csaki, Csaba
Partner: UNT Libraries Government Documents Department

SUSY Unparticle and Conformal Sequestering

Description: We investigate unparticle physics with supersymmetry (SUSY). The SUSY breaking effects due to the gravity mediation induce soft masses for the SUSY unparticles and hence break the conformal invariance. The unparticle physics observable in near future experiments is only consistent if the SUSY breakingeffects from the hidden sector to the standard model sector are dominated by the gauge mediation, or if the SUSY breaking effects to the unparticle sector are sufficiently sequestered. We argue that the natural realization of the latter possibility is the conformal sequestering scenario.
Date: July 17, 2007
Creator: Nakayama, Yu & Nakayama, Yu
Partner: UNT Libraries Government Documents Department

Supersymmetry without the Desert

Description: Naturalness of electroweak symmetry breaking in weak scale supersymmetric theories may suggest the absence of the conventional supersymmetric desert. We present a simple, realistic framework for supersymmetry in which (most of) the virtues of the supersymmetric desert are naturally reproduced without having a large energy interval above the weak scale. The successful supersymmetric prediction for the low-energy gauge couplings is reproduced due to a gauged R symmetry present in the effective theory at the weak scale. The observable sector superpotential naturally takes the form of the next-to-minimal supersymmetric standard model, but without being subject to the Landau pole constraints up to the conventional unification scale. Supersymmetry breaking masses are generated by the F-term and D-term VEVs of singlet and U(1){sub R} gauge fields, as well as by anomaly mediation, at a scale not far above the weak scale. We study the resulting pattern of supersymmetry breaking masses in detail, and find that it can be quite distinct. We construct classes of explicit models within this framework, based on higher dimensional unified theories with TeV-sized extra dimensions. A similar model based on a non-R symmetry is also presented. These models have a rich phenomenology at the TeV scale, and allow for detailed analyses of, e.g., electroweak symmetry breaking.
Date: September 26, 2006
Creator: Nomura, Yasunori & Poland, David
Partner: UNT Libraries Government Documents Department

Models of Scherk-Schwarz Symmetry Breaking in 5D: Classification and Calculability

Description: The form of the most general orbifold breaking of gauge, global and supersymmetries with a single extra dimension is given. In certain theories the Higgs boson mass is ultraviolet finite due to an unbroken local supersymmetry, which is explicitly exhibited. We construct: a 1 parameter SU(3) \times SU(2) \times U(1) theory with 1 bulk Higgs hypermultiplet, a 2 parameter SU(3) \times SU(2) \times U(1) theory with 2 bulk Higgs hypermultiplets, and a 2 parameter SU(5) \to SU(3) \times SU(2) \times U(1) theory with 2 bulk Higgs hypermultiplets, and demonstrate that these theories are unique. We compute the Higgs mass and compactification scale in the SU(3) \times SU(2) \times U(1) theory with 1 bulk Higgs hypermultiplet.
Date: July 1, 2001
Creator: Barbieri, Riccardo; Hall, Lawrence J. & Nomura, Yasunori
Partner: UNT Libraries Government Documents Department

The Measurement of xi'/xi at Fermilab KTeV-E832

Description: The status of the analysis effort for the 25% data sample taken during the Fermilab '96-'97 fixed target run for {epsilon}'/{epsilon} measurement from KTeV is presented here. Detector performance, data statistics, background subtractions, data and monte-carlo comparison for acceptance corrections, as well as the preliminary results on K{sub L}{yields}{pi}{sup 0}{gamma}{gamma} are described in more detail. Prospects for KTeV 99, in the up coming 6 months '99 fixed target run, are also discussed here.
Date: February 15, 1999
Creator: Hsiung, Yee Bob
Partner: UNT Libraries Government Documents Department

Topcolor and the First Muon Collider

Description: We describe a class of models of electroweak symmetry breaking that involve strong dynamics and top quark condensation. A new scheme based upon a seesaw mechanism appears particularly promising. Various implications for the first-stage muon collider are discussed.
Date: April 1, 1998
Creator: Hill, C.T.
Partner: UNT Libraries Government Documents Department

Status of the KTeV experiment at Fermilab

Description: The KTeV experiment is a fixed target experiment at Fermilab. Its primary goal is the search for direct CP violation in the decay of neutral kaons. Its current status and some preliminary results will be discussed.
Date: October 1, 1997
Creator: Ben-David, R. & Collaboration, KTeV
Partner: UNT Libraries Government Documents Department

Prospects for cp violation searches at Tevatron

Description: In the near future CP violation measurements will be one of the most crucial test for the Standard Model. Several B factories are going to be built to study these phenomena in the B system. These goals can be achieved also at the Tevatron Collider by the two experiments: CDF and D0. Starting from data collected during Run I the sensitivity expected in Run II is shown.
Date: September 1, 1997
Creator: Lucchesi, D.
Partner: UNT Libraries Government Documents Department

Superstring phenomenology present-and-future perspective

Description: The objective of superstring phenomenology is to develop the models and methodology needed to connect quantitatively between Planck scale and electroweak scale experimental data. I review the present status of this endeavor with a focus on the three generation free fermionic models.
Date: July 1, 1997
Creator: Faraggi, A.E.
Partner: UNT Libraries Government Documents Department

Supersymmetry breaking in superstring theory by Gaugino condensation and its phenomenology

Description: Weakly-coupled heterotic string is known to have problems of dilaton/moduli stabilization, supersymmetry breaking (by hidden-sector gaugino condensation), gauge coupling unification, QCD axion, as well as cosmological problems involving dilaton/moduli and axion. The author studies these problems by adopting the point of view that they arise mostly due to limited calculational power, little knowledge of the full vacuum structure, and an inappropriate treatment of gaugino condensation. It turns out that these problems can be solved or are much less severe after a more consistent and complete treatment. There are two kinds of non-perturbative effects in the construction of string effective field theory: the field-theoretical non-perturbative effects of gaugino condensation (with an important constraint ignored in the past) and the stringy nonperturbative effects conjectured by S. Shenker, which are best described using the linear multiplet formalism. Stringy non-perturbative corrections to the Kaehler potential are invoked to stabilize the dilaton at a value compatible with a weak coupling regime. Modular invariance is ensured through the Green-Schwarz counterterm and string threshold corrections which, together with hidden matter condensation, lead to moduli stabilization at the self-dual point where the vev`s of moduli`s F components vanish. In the vacuum, supersymmetry is broken at a realistic scale with vanishing cosmological constant. As for soft supersymmetry breaking, this model always leads to a dilaton-dominated scenario. For the strong CP problem, the model-independent axion has the right properties to be the QCD axion. Furthermore, there is a natural hierarchy between the dilaton/moduli mass and the gravitino mass, which could solve both the cosmological moduli problem and the cosmological problem of the model-independent axion.
Date: May 1, 1997
Creator: Wu, Yi-Yen
Partner: UNT Libraries Government Documents Department

The cosmological constant: Plus CA change, plus C`est La Meme Chose

Description: Recent measurements of the cosmological parameters have renewed interest in the cosmological constant {Lambda}. I briefly review the current status of these measurements and the corresponding arguments for and against cosmological models with non-zero {Lambda}. I outline a scenario which attempts to incorporate non-zero vacuum energy into the framework of particle physics, based on an ultra-light pseudo-Nambu-Goldstone boson. With global spontaneous symmetry breaking scale f {approx_equal} 10{sup 18} GeV and explicit breaking scale comparable to MSW neutrino masses, M {approximately} 10{sup -3} eV, such a field, which acquires a mass M{sub {phi}} {approximately} M{sup 2}/f {approximately} H{sub 0}, would have become dynamical at recent epochs and currently dominate the energy density of the universe. The field acts as an effective cosmological constant for several expansion times and then relaxes into a condensate of coherent non-relativistic bosons. Such a model can reconcile dynamical estimates of the density parameter, {Omega}{sub m} {approximately} 0.2, with a spatially flat universe, and can yield an expansion age H{sub 0}t{sub 0} {approx_equal} 1 while remaining consistent with limits from gravitational lens statistics.
Date: February 1, 1998
Creator: Frieman, J.A.
Partner: UNT Libraries Government Documents Department

The pooltable analogy to axion physics

Description: An imaginary character named TSP finds himself in a playroom whose floor is tilted to one side. However, the pooltable in the playroom is horizontal. TSP wonders how this can be. In doing so, he embarks upon an intellectual journey which parallels that which has been travelled during the past two decades by physicists interested in the Strong CP Problem and axion physics.
Date: January 1, 1996
Creator: Sikivie, P.
Partner: UNT Libraries Government Documents Department

Research in baryon number violation at the superconducting supercollider

Description: This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). One of the most startling events imaginable at a future high-energy collider would be the observation of baryon (B) and lepton (L) number violation. It is surprising that this possibility is not a priori ruled out by our current theoretical understanding of the Standard Model of electroweak forces - despite the best efforts of leading theorists over the last two and one half years. In fact, initial semi-classical calculations using instantons have suggested that, at supercollider-range energies, B- and L-violating processes might occur at an observable rate. Our project has consisted of a theoretical exploration of the possibility of observing B and L violation at future very-high-energy colliders. The techniques developed for addressing this problem should impact more generally on our understanding of weakly-coupled field theories in the non- perturbative regime where both energies and multiplicities are very large. We have made significant progress in our theoretical understanding of anomalous electroweak processes that might be seen at the next generation of supercolliders. With the official cancellation of the Superconducting Supercollider, we have worked to reapply many of these ideas - with great success to date - to the realm of the strong interactions, using Skyrmion methods.
Date: July 1, 1996
Creator: Mattis, M.; Dorey, N.; Silbar, R. & Hughes, J.
Partner: UNT Libraries Government Documents Department

The experimental investigation of supersymmetry breaking

Description: If Nature is supersymmetric at the weak interaction scale, what can we hope to learn from experiments on supersymmetric particles? The most mysterious aspect of phenomenological supersymmetry is the mechanism of spontaneous supersymmetry breaking. This mechanism ties the observable pattern of supersymmetric particle masses to aspects of the underlying unified theory at very small distance scales. In this article, I will discuss a systematic experimental program to determine the mechanism of supersymmetry breaking. Both pp and e{sup +}e{sup -} colliders of the next generation play an essential role.
Date: April 1, 1996
Creator: Peskin, M.E.
Partner: UNT Libraries Government Documents Department

Non-universal SUSY breaking, hierarchy and squark degeneracty

Description: I discuss non-trivial effects in the soft SUSY breaking terms which appear when one integrates out heavy fields. The effects exist only when the SUSY breaking terms are non-universal. They may spoil (1) the hierarchy between the weak and high-energy scales, or (2) degeneracy among the squark masses even in the presense of a horizontal symmetry. I argue, in the end, that such new effects may be useful in probing physics at high-energy scales from TeV-scale experiments.
Date: March 15, 1995
Creator: Murayama, Hitoshi
Partner: UNT Libraries Government Documents Department