More modular invariant anomalous U(1) breaking

Gaillard, Mary K.; Giedt, Joel

doi:10.1016/s0550-3213(02)00686-7

Cited by 10 publications

(7 citation statements)

References 33 publications

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“…Thus, fields which take vacuum values to cancel the anomalous U(1) FI term must be removed from the theory in modular invariant (and U(1) invariant) combinations. For example, if the field Y carries anomalous U(1) charge q X Y and acquires a vacuum value Y = 0, then the appropriate combination to integrate out of the theory is [55,56] e 2q X Y V X (T + T…”

Section: More Sophisticated Modelsmentioning

confidence: 99%

Theoretical implications of the CERN LEP Higgs search

et al. 2005

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We study the implications for the minimal supersymmetric standard model (MSSM) of the absence of a direct discovery of a Higgs boson at LEP. First we exhibit 15 physically different ways in which one or more Higgs bosons lighter than the LEP limit could still exist. For each of these cases -as well as the case that the lightest Higgs eigenstate is at, or slightly above, the current LEP limit -we provide explicit sample configurations of the Higgs sector as well as the soft supersymmetry breaking Lagrangian parameters necessary to generate these outcomes. We argue that all of the cases seem fine-tuned, with the least fine-tuned outcome being that with m h ≃ 115 GeV. Seeking to minimize this tuning we investigate ways in which the "maximal-mixing" scenario with large topquark trilinear A-term can be obtained from simple string-inspired supergravity models. We find these obvious approaches lead to heavy gauginos and/or problematic low-energy phenomenology with minimal improvement in fine-tuning. PACS numbers:The Minimal Supersymmetric Standard Model is defined as the simplest supersymmetric extension of the Standard Model (SM). Every SM particle has a superpartner, the basic Lagrangian is supersymmetric, and the gauge group is the same SU (3) × SU (2) × U (1) as that of the SM. The full supersymmetry is softly broken by certain dimension two and three operators. There is considerable indirect evidence that this theory is likely to be part of the description of nature. If it is, a Higgs boson with mass less than about 130 GeV must exist, and superpartners must be found with masses not too much larger than those of the W, Z and top quark. While the Higgs boson mass can be as heavy as 130 GeV in the MSSM, it has been known for some time that most naive models imply a lighter state, usually below about 110 GeV, when constraints from non-observation of superpartners (real or virtual) are imposed, and including the constraint that the indirect arguments for supersymmetry are valid without fine-tuning.While it is not impossible that perhaps LEP has seen a Higgs boson with m h ≃ 115 GeV, the data collected up through center-of-mass energy of 209 GeV [1] yields no unambiguous signal for such a light Higgs eigenstate. One obvious explanation for this fact is that the lightest Higgs boson is heavier than 115 GeV. Another is that one or more eigenstates are lighter than the kinematic cut-off but that they do not couple significantly to the Z-boson. Thus it is natural to ask whether the Higgs sector of the MSSM could be such that LEP would not have found a signal because of reduced Higgs cross sections or reduced branching ratios in some part of the general MSSM parameter space. Using the reported LEP limits on the cross-section × branching ratio for Higgs eigenstates as a guide, it is possible to find 15 logically distinct ways in which this could indeed have been the case at LEP. Together with the possibility that the lightest Higgs boson is at 115 GeV, and the possibility that it is much larger in mass, there are 17 distinct...

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Section: More Sophisticated Modelsmentioning

confidence: 99%

Theoretical implications of the CERN LEP Higgs search

et al. 2005

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“…An important property of ( 160) is to recognize that the factor of b + , containing as it does a loop factor, will suppress the magnitude of the auxiliary field F S relative to that of the supergravity auxiliary field M through the relation (162). That is, provided K s ∼ O(1) so that K s b + ≪ 1 we can immediately see that a Kähler potential which stabilizes the dilaton (while simultaneously providing zero vacuum energy) will necessarily result in a suppressed dilaton contribution to soft supersymmetry breaking.…”

Section: Moduli As Messengers Of Supersymmetry Breakingmentioning

confidence: 99%

“…Since the linear multiplet formalism for the dilaton is by far better suited to addressing these questions, we will use it in these two sections, and impose further that the modified linearity condition (42) remain true in the effective theory below the U (1) X breaking scale. The cases with any number m of broken U (1)'s and n ≥ m scalar vevs have been worked out in detail; 162,55 here we simply state the results. In Section 4.3 we discuss the vacuum and the moduli sector, and in Sections 4.4 and 4.5 we address observable sector and D-moduli masses, respectively, and discuss the requirements for a viable model.…”

Section: Inclusion Of Anomalous U(1)'smentioning

confidence: 99%

Kähler Stabilized, Modular Invariant Heterotic String Models

Gaillard

Nelson

2007

Int. J. Mod. Phys. A

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We review the theory and phenomenology of effective supergravity theories based on orbifold compactifications of the weakly-coupled heterotic string. In particular, we consider theories in which the four-dimensional theory displays target space modular invariance and where the dilatonic mode undergoes Kähler stabilization. A self-contained exposition of effective Lagrangian approaches to gaugino condensation and heterotic string theory is presented, leading to the development of the models of Binétruy, Gaillard and Wu. Various aspects of the phenomenology of this class of models are considered. These include issues of supersymmetry breaking and superpartner spectra, the role of anomalous U (1) factors, issues of flavor and R-parity conservation, collider signatures, axion physics, and early universe cosmology. For the vast majority of phenomenological considerations the theories reviewed here compare quite favorably to other string-derived models in the literature. Theoretical objections to the framework and directions for further research are identified and discussed.

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“…In models with an anomalous U(1) X , there is a Green-Schwarz counterterm in the form of a D-term [11] that leads to the breaking of a number m of U(1) gauge factors when n ≥ m fields Φ A acquire vev's. T-duality remains unbroken [12], but the modular weights are modified by going to unitary gauge in a way that keeps modular invariance manifest. For example in minimal models with n = m:…”

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confidence: 99%