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An alternative NMSSM phenomenology with manifest perturbative unification

Description: Can supersymmetric models with a moderate stop mass be made consistent with the negative Higgs boson searches at LEP, while keeping perturbative unification manifest? The NMSSM achieves this rather easily, but only if extra matter multiplets filling complete SU(5) representations are present at intermediate energies. As a concrete example which makes use of this feature, we give an analytic description of the phenomenology of a constrained NMSSM close to a Peccei-Quinn symmetry point. The related pseudo-Goldstone boson appears in decays of the Higgs bosons and possibly of the lightest neutralino, and itself decays into (b anti-b) and (tau anti-tau).
Date: December 18, 2007
Creator: Hall, Lawrence; Barbieri, Riccardo; Pappadopulo, Duccio; Rychkov, Vyacheslav S.; Hall, Lawrence J. & Papaioannou, Anastasios Y.
Partner: UNT Libraries Government Documents Department

Flavorful supersymmetry

Description: Weak scale supersymmetry provides elegant solutions to many of the problems of the standard model, but it also generically gives rise to excessive flavor and CP violation. We show that, if the mechanism that suppresses the Yukawa couplings also suppresses flavor changing interactions in the supersymmetry breaking parameters, essentially all the low energy flavor and CP constraints can be satisfied. The standard assumption of flavor universality in the supersymmetry breaking sector is not necessary. We study signatures of this framework at the LHC. The mass splitting among different generations of squarks and sleptons can be much larger than in conventional scenarios, and even the mass ordering can be changed. We find that there is a plausible scenario in which the next-to-lightest superparticle is a long-lived right-handed selectron or smuon which decays into the lightest superparticle, a gravitino. This leads to the spectacularsignature of monochromatic electrons or muons in a stopper detector, providing strong evidence for the framework.
Date: December 13, 2007
Creator: Nomura, Yasunori; Nomura, Yasunori; Papucci, Michele & Stolarski, Daniel
Partner: UNT Libraries Government Documents Department

Anomalous U(1) and low-energy physics: the power of D-flatness and holomorphy

Description: In models with an anomalous abelian symmetry broken at a very large scale, we study which requirements to impose on the anomalous charges in order to prevent standard model fields from acquiring large vacuum expectation values. The use of holomorphic invariants to study D-flat directions for the anomalous symmetry, proves to be a very powerful tool. We find that in order to forbid unphysical configurations at that scale, the superpotential must contain many interaction terms, including the usual Yukawa terms. Our analysis suggests that the anomalous charge of the {mu}-term is zero. It is remarkable that, together with the seesaw mechanism, and mass hierarchies, this implies a natural conservation of R-parity.
Date: December 1, 1996
Creator: Binetruy, P.; Irges, N.; Lavignac, S. & Ramond, P.
Partner: UNT Libraries Government Documents Department

Z' Bosons, the NuTeV Anomaly, and the Higgs Boson Mass

Description: Fits to the precision electroweak data that include the NuTeV measurement are considered in family universal, anomaly free U(1) extensions of the Standard Model. In data sets from which the hadronic asymmetries are excluded, some of the Z{prime} models can double the predicted value of the Higgs boson mass, from {approx} 60 to {approx} 120 GeV, removing the tension with the LEP II lower bound, while also modestly improving the {chi}{sup 2} confidence level. The effect of the Z{prime} models on both m{sub H} and the {chi}{sup 2} confidence level is increased when the NuTeV measurement is included in the fit. Both the original NuTeV data and a revised estimate by the PDG are considered.
Date: March 3, 2009
Creator: Chanowitz, Michael S
Partner: UNT Libraries Government Documents Department

Will at least one of the Higgs bosons of the next-to-minimal supersymmetric extension of the standard model be observable at LEP2 or the LHC?

Description: We demonstrate that there are regions of parameter space in the next-to-minimal (i.e. two-Higgs-doublet, one-Higgs-singlet superfield) supersymmetric extension of the SM for which none of the Higgs bosons are observable either at LEP2 with $\sqrt{s}=192 GeV$ and an integrated luminosity of $L=1000inverse pb$ or at the LHC with $L=600 inverse fb$.
Date: June 24, 1996
Creator: Gunion, John F.; Haber, Howard E. & Moroi, Takeo
Partner: UNT Libraries Government Documents Department

DO -- antiMixing and Rare Charm Decays

Description: We review the current status of flavor-changing neutral currents in the charm sector. We focus on the standard-model predictions and identify the main sources of theoretical uncertainties in both charm mixing and rare charm decays. The potential of these observables for constraining short-distance physics in the standard model and its extensions is compromised by the presence of large nonperturbative effects. We examine the possible discovery windows in which short-distance physics can be tested and study the effects of various extensions of the standard model. The current experimental situation and future prospects are reviewed.
Date: October 6, 2003
Creator: Miller, Jeanne M & Burdman, Gustavo
Partner: UNT Libraries Government Documents Department

Dark Matter before the LHC in a Natural Supersymmetric StandardModel

Description: We show that the solid lower bound of about 10{sup -44} cm{sup 2} is obtained for the cross section between the supersymmetric dark matter and nucleon in a theory in which the supersymmetric fine-tuning problem is solved without extending the Higgs sector at the weak scale. This bound arises because of relatively small superparticle masses and a fortunate correlation that the two dominant diagrams for the dark matter detection always interfere constructively if the constraint from the b {yields} s{gamma} measurements is obeyed. It is, therefore, quite promising in the present scenario that the supersymmetric dark matter is discovered before the LHC, assuming that the dark matter is the lightest supersymmetric particle.
Date: September 21, 2005
Creator: Ryuichiro, Kitano & Yasunori, Nomura
Partner: UNT Libraries Government Documents Department

Supersymmetry and Superstring Phenomenology

Description: We briefly cover the early history of supersymmetry, describe the relation of SUSY quantum field theories to superstring theories and explain why they are considered a likely tool to describe the phenomenology of high energy particle theory beyond the Standard Model.
Date: May 5, 2008
Creator: Gaillard, Mary K; Gaillard, Mary K. & Zumino, Bruno
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

Implications of the measurement of the B0s Bbar0s massdifference

Description: We analyze the significant new model independent constraints on extensions of the standard model (SM) that follow from the recent measurements of the B{sup 0}{sub s} {bar B}{sup 0}{sub s} mass difference. The time-dependent CP asymmetry in B{sub s} {yields} {psi}{phi}, S{sub {psi}{phi}}, will be measured with good precision in the first year of LHC data taking, which will further constrain the parameter space of many extensions of the SM, in particular, next-to-minimal flavor violation. The CP asymmetry in semileptonic B{sub s} decay, A{sup s}{sub SL}, is also important to constrain these frameworks, and could give further clues to our understanding the flavor sector in the LHC era. We point out a strong correlation between S{sub {psi}{phi}} and A{sup s}{sub SL} in a very broad class of new physics models.
Date: April 20, 2006
Creator: Ligeti, Zoltan; Papucci, Michele & Perez, Gilad
Partner: UNT Libraries Government Documents Department

A New Limit on Time-Reversal Violation in Beta Decay

Description: We report the results of an improved determination of the triple correlation DP {center_dot} (p{sub e} x p{sub v}) that can be used to limit possible time-reversal invariance in the beta decay of polarized neutrons and constrain extensions to the Standard Model. Our result is D = (-0.96 {+-} 1.89(stat) {+-} 1.01(sys)) x 10{sup -4}. The corresponding phase between g{sub A} and g{sub V} is {phi}{sub AV} = 180.013{sup o} {+-} 0.028{sup o} (68% confidence level). This result represents the most sensitive measurement of D in nuclear beta decay.
Date: April 26, 2011
Creator: Mumm, H P; Chupp, T E; Cooper, R L; Coulter, K P; Freedman, S J; Fujikawa, B K et al.
Partner: UNT Libraries Government Documents Department

A Constrained Standard Model: Effects of Fayet-Iliopoulos Terms

Description: In [1]the one Higgs doublet standard model was obtained by an orbifold projection of a 5D supersymmetric theory in an essentially unique way, resulting in a prediction for the Higgs mass m_H = 127 +- 8 GeV and for the compactification scale 1/R = 370 +- 70 GeV. The dominant one loop contribution to the Higgs potential was found to be finite, while the above uncertainties arose from quadratically divergent brane Z factors and from other higher loop contributions. In [3], a quadratically divergent Fayet-Iliopoulos term was found at one loop in this theory. We show that the resulting uncertainties in the predictions for the Higgs boson mass and the compactification scale are small, about 25percent of the uncertainties quoted above, and hence do not affect the original predictions. However, a tree level brane Fayet-Iliopoulos term could, if large enough, modify these predictions, especially for 1/R.
Date: October 7, 2001
Creator: Barbieri, Riccardo; Hall, Lawrence J. & Nomura, Yasunori
Partner: UNT Libraries Government Documents Department

Squark Mixing Contributions to CP violating phase gamma

Description: We investigate the possibility that the CP violation due to the soft supersymmetry breaking terms in squark mixing can give significant contributions to the various $\gamma$ related parameters in B decays, different from those of the Standard Model. We derive the new limits on $(\delta^u_12)_LL,LR,RR$ and on $(\delta^d_23)_LL,LR,RR$ from the recent data on $D^0$--$\barD^0$ oscillation as well as those on $B_s^0$--$\barB_s^0$ oscillation. We show that, together with all the other constraints, the currents limits on these parameters still allow large contributions to the CP violating phases in $B_s^0$--$\bar{B_s}^0$ as well as $D^0$--$\barD^0$ oscillations which will modify some of the proposed measurements of $\gamma$ parameters in CP violating B decays. However, the current constraints already dictate that the one-loop squark mixing contributions to various B decay amplitudes cannot be competitive with that of the Standard Model (SM), at least for those B decay modes which are dominated the tree level amplitudes within the SM, and therefore they are not significant in contributing to CP asymmetries in the corresponding B decays.
Date: September 17, 2001
Creator: Chang, Darwin; Chang, We-Fu; Keung, Wai-Yee; Sinha, Nita & Sinha, Rahul
Partner: UNT Libraries Government Documents Department

Report of the subgroup on alternative models and new ideas

Description: We summarize some of the work done by the P3 subgroup on Alternative Models and New Ideas. The working group covered a broad range of topics including a constrained Standard Model from an extra dimension, a discussion of recent ideas addressing the strong CP problem, searches for doubly charged higgs bosons in e{gamma} collisions, and an update on discovery limits for extra neutral gauge bosons at hadron colliders. The breadth of topics rejects the many ideas and approaches to physics beyond the Standard Model.
Date: November 19, 2002
Creator: Chertok, M.; Dienes, K.; Godfrey, S.; Kalyniak, P.; Kaplan, D.; Kribs, G. D. et al.
Partner: UNT Libraries Government Documents Department

A high energy physics perspective

Description: The status of the Standard model and role of symmetry in its development are reviewed. Some outstanding problems are surveyed and possible solutions in the form of additional {open_quotes}Hidden Symmetries {close_quotes} are discussed. Experimental approaches to uncover {open_quotes}New Physics{close_quotes} associated with those symmetries are described with emphasis on high energy colliders. An outlook for the future is given.
Date: January 13, 1997
Creator: Marciano, W. J.
Partner: UNT Libraries Government Documents Department

Standard model higgs and top mass measurements at the Tevatron

Description: A summary of the present Standard Model Higgs search and measurement of top quark mass at the Tevatron are presented. The sensitivity of the present Higgs search at the Tevatron is limited by statistics to a cross section approximately two orders of magnitude higher than the predicted cross section for standard model Higgs production. With 30 fb{sup -1} of integrated luminosity, the Tevatron offers an unique potential discovery window for the Standard Model Higgs mass up to 130 GeV/c{sup 2} before LHC era. The study of top at the Tevatron has moved from discovery phase to one of characterizing its properties. The combined result of top quark mass is 174.3 {+-} 5.1 GeV/c{sup 2} ({delta}m{sub t} =m{sub t} < 3%).
Date: April 19, 1999
Creator: Yao, W.-M.
Partner: UNT Libraries Government Documents Department

Searches for beyond the MSSM phenomena at CDF

Description: CDF searches for R{sub p} violation, extra quark generations, and long-lived charged massive particles are presented. These phenomena are not predicted by the Minimal Supersymmetric Standard Model (MSSM) and therefore complement the classic SUSY searches. Prospects for continuing these analyses during Run II of the Tevatron are outlined.
Date: April 13, 1999
Creator: Chertok, M.
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

Negative contributions to S in an effective field theory

Description: We show that an effective field theory that includes non-standard couplings between the electroweak gauge bosons and the top and bottom quarks may yield negative contributions to both the S and T oblique radiative electroweak parameters. We find that such an effective field theory provides a better fit to data than the standard model (the {chi}{sup 2} per degree of freedom is half as large). We examine in some detail an illustrative model where the exchange of heavy scalars produces the correct type of non-standard couplings.
Date: September 19, 1997
Creator: Dobrescu, Bogdan A. & Terning, John
Partner: UNT Libraries Government Documents Department

D0-D bar 0 mixing and rare charm decays

Description: We review the current status of flavor-changing neutral currents in the charm sector. We focus on the standard-model predictions and identify the main sources of theoretical uncertainties in both D{sup 0} - {bar D}{sup 0} mixing and rare charm decays. The potential of these observables for constraining short-distance physics in the standard model and its extensions is compromised by the presence of large nonperturbative effects. We examine the possible discovery windows in which short-distance physics can be tested and study the effects of various extensions of the standard model. The current experimental situation and future prospects are reviewed.
Date: October 8, 2003
Creator: Burdman, Gustavo & Shipsey, Ian
Partner: UNT Libraries Government Documents Department

Higgs searches in run 2 at the Tevatron

Description: In Run 2 at the Tevatron, the upgraded CDF and D0 experiments will have greatly improved sensitivity in the search for the Higgs bosons of the Standard Model and minimal supersymmetry. In the past year the Higgs Working Group of the Tevatron Run 2 SUSY/Higgs Workshop has estimated the discovery and exclusion reach for the Higgs, combining all possible search channels and utilizing all the upgraded features of both detectors. The results give strong motivation to continue the next run of the Tevatron into Run 3, with an eventual goal of up to 20 fb<sup>-1</sup> or more delivered per experiment.
Date: July 13, 1999
Creator: Conway, John S.
Partner: UNT Libraries Government Documents Department

Infrared fixed point solution for the top quark mass and unification of couplings in the MSSM

Description: We analyze the implications of the infrared quasi fixed point solution for the top quark mass in the Minimal Supersymmetric Standard Model. This solution could explain in a natural way the relatively large value of the top quark mass and, if confirmed experimentally, may be suggestive of the onset of nonperturbative physics at very high energy scales. In the framework of grand unification, the expected bottom quark -- tau lepton Yukawa coupling unification is very sensitive to the fixed point structure of the top quark mass. For the presently allowed values of the electroweak parameters and the bottom quark mass, the Yukawa coupling unification implies that the top quark mass must be within ten percent of its fixed point values.
Date: August 1, 1993
Creator: Bardeen, W.A.; Carena, M.; Pokorski, S. & Wagner, C.E.M.
Partner: UNT Libraries Government Documents Department