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Adam Falkowski

Publications and source records attributed to Adam Falkowski.

At least 91 records · Page 5Linked to original sources
arXiv2008

Holographic Unhiggs

We propose an extra-dimensional approach to the unparticle Higgs (Unhiggs). The non-local 4D Unhiggs action is derived as the boundary effective action of a local 5D theory. We review the mechanism to generate unparticle spectra in the context of warped soft-wall models. Gauge invariance can be simply implemented and unitarity of the longitudinal WW scattering amplitude is particularly transparent. Furthermore, the 5D approach uncovers a broader spectrum of phenomenological possibilities. The Unhiggs is accompanied by another continuum formed by Kaluza-Klein excitations of the Standard Model gauge fields which, in some cases, may take over the leading role in unitarizing WW scattering.

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arXiv2008

A New Approach to mu-Bmu

We present a new approach to the mu-Bmu problem of gauge mediated supersymmetry breaking. Rather than reducing the generically large contribution to Bmu we point out that acceptable electroweak symmetry breaking can be achieved with mu^2 << Bmu if at the same time Bmu << m_Hd^2. This hierarchy can easily appear in models where the Higgs fields are directly coupled to the supersymmetry breaking sector. Such models can yield novel electroweak symmetry breaking vacua, can deal with the supersymmetric flavor and CP problems, allow for gauge coupling unification, and result in distinct phenomenological predictions for the spectrum of superparticles.

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arXiv2008

A Simple Flavor Protection for RS

We present a simple variation of warped flavor models where the hierarchies of fermion masses and mixings are still explained but dangerous flavor violating effects in the Kaon sector are greatly reduced. The key new ingredients are two horizontal U(1) symmetries. These symmetries forbid flavor violation in the down quark sector (with the exception of small IR brane localized kinetic mixing terms for the left-handed quarks) while allowing for flavor violation in the up quark sector. The leading flavor constraints come from D - anti-D mixing, and are safely satisfied for the KK mass scale of order 3 TeV. Our analysis of the flavor constraints also includes the constraints due to the (usually ignored) localized kinetic mixing terms. We also comment on the effects of the additional U(1) gauge bosons.

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arXiv2008

Electroweak Breaking on a Soft Wall

We extend the 5D gauge-higgs scenario to the soft-wall framework where the IR brane is replaced by a smoothly decaying warp factor. The electroweak symmetry of the Standard Model is embedded in a larger symmetry group whose gauge bosons propagate in the bulk of a warped fifth dimension. This gauge symmetry is partly broken by UV boundary conditions and by a condensate of a bulk scalar field. The Higgs boson lives partly in the 5th component of the gauge field, and partly in the the bulk scalar. The Higgs potential is not UV sensitive if the condensate vanishes fast enough in the UV region. The soft-wall realization opens new possibilities for the spectrum and the couplings of the Kaluza-Klein resonances. We study two particular soft-wall backgrounds: one with resonances whose masses follow the linear Regge trajectory, and another with a continuum above a mass gap. We find that constraints on the Kaluza-Klein scale from electroweak precision tests are less severe than in analogous models with the IR brane. For the linear spectrum the typical constraint on the lightest resonance mass is 2 TeV, while the continuum is allowed to start below 1 TeV.

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arXiv2008

The Flavor of the Composite Pseudo-Goldstone Higgs

We study the flavor structure of 5D warped models that provide a dual description of a composite pseudo-Goldstone Higgs. We first carefully re-examine the flavor constraints on the mass scale of new physics in the standard Randall-Sundrum-type scenarios, and find that the KK gluon mass should generically be heavier than about 21 TeV. We then compare the flavor structure of the composite Higgs models to those in the RS model. We find new contributions to flavor violation, which while still are suppressed by the RS-GIM mechanism, will enhance the amplitudes of flavor violations. In particular, there is a kinetic mixing term among the SM fields which (although parametrically not enhanced) will make the flavor bounds even more stringent than in RS. This together with the fact that in the pseudo-Goldstone scenario Yukawa couplings are set by a gauge coupling implies the KK gluon mass to be at least about 33 TeV. For both the RS and the composite Higgs models the flavor bounds could be stronger or weaker depending on the assumption on the value of the gluon boundary kinetic term. These strong bounds seem to imply that the fully anarchic approach to flavor in warped extra dimensions is implausible, and there have to be at least some partial flavor symmetries appearing that eliminate part of the sources for flavor violation. We also present complete expressions for the radiatively generated Higgs potential of various 5D implementations of the composite Higgs model, and comment on the 1-5 percent level tuning needed in the top sector to achieve a phenomenologically acceptable vacuum state.

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arXiv2007

Pseudo-Goldstone Higgs Production via Gluon Fusion

The gluon-gluon-higgs amplitude is investigated in the context of 5D models of gauge-higgs unification. A simple algorithm allows to include, in a fully analytical way, the contribution of the whole Kaluza-Klein tower of a 5D quark to the amplitude. This algorithm is applied to realistic models based on SO(5) symmetry. Within the studied classes of models, the higgs production cross section is always suppressed.

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arXiv2007

KK Parity in Warped Extra Dimension

We construct models with a Kaluza-Klein (KK) parity in a five- dimensional warped geometry, in an attempt to address the little hierarchy problem present in setups with bulk Standard Model fields. The lightest KK particle (LKP) is stable and can play the role of dark matter. We consider the possibilities of gluing two identical slices of 5D AdS in either the UV (IR-UV-IR model) or the IR region (UV-IR-UV model) and discuss the model-building issues as well as phenomenological properties in both cases. In particular, we find that the UV-IR-UV model is not gravitationally stable and that additional mechanisms might be required in the IR-UV-IR model in order to address flavor issues. Collider signals of the warped KK parity are different from either the conventional warped extra dimension without KK parity, in which the new particles are not necessarily pair-produced, or the KK parity in flat universal extra dimensions, where each KK level is nearly degenerate in mass. Dark matter and collider properties of a TeV mass KK Z gauge boson as the LKP are discussed.

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arXiv2007

Modelling strong interactions and longitudinally polarized vector boson scattering

We study scattering of the electroweak gauge bosons in 5D warped models. Within two different models we determine the precise manner in which the Higgs boson and the vector resonances ensure the unitarity of longitudinal vector boson scattering. We identify three separate scales that determine the dynamics of the scattering process in all cases. For a quite general background geometry of 5D, these scales can be linked to a simple functional of the warp factor. The models smoothly interpolate between a `composite' Higgs limit and a Higgsless limit. By holographic arguments, these models provide an effective description of vector boson scattering in 4D models with a strongly coupled electroweak breaking sector.

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arXiv2007

Electroweak observables in a general 5D background

Warped extra dimensions provide a new playground to study electroweak brea-king and the nature of the higgs field. In this paper we reanalyze the electroweak observables in theories with one extra dimension and a completely general warp factor. We demonstrate that, regardless of the 5D background, SU(2)_R is needed in order to avoid excessive contributions to the T parameter. For higgsless theories cancelations between different contributions to the S parameter are needed.

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arXiv2006

About the holographic pseudo-Goldstone boson

Pseudo-Goldstone bosons in 4D strongly coupled theories have a dual description in terms of 5D gauge theories in warped backgrounds. We introduce systematic methods of computing the pseudo-Goldstone potential for an arbitrary warp factor in 5D. When applied to electroweak symmetry breaking, our approach clarifies the relation of physical observables to geometrical quantities in five dimensions.

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arXiv2006

Holography, Pade Approximants and Deconstruction

We investigate the relation between holographic calculations in 5D and the Migdal approach to correlation functions in large N theories. The latter employs Pade approximation to extrapolate short distance correlation functions to large distances. We make the Migdal/5D relation more precise by quantifying the correspondence between Pade approximation and the background and boundary conditions in 5D. We also establish a connection between the Migdal approach and the models of deconstructed dimensions.

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arXiv2006

SUSY Phenomenology of KKLT Flux Compactifications

We study SUSY phenomenology of the KKLT (Kachru-Kallosh-Linde-Trivedi) scenario of string theory compactifications with fluxes. This setup leads to a specific pattern of soft masses and distinct phenomenological properties. In particular, it avoids the cosmological gravitino/moduli problems. Remarkably, the model allows for the correct abundance of SUSY dark matter consistently with all experimental constraints including the bound on the Higgs mass, b-->s gamma, etc. This occurs for both small and large tan beta, and requires the SUSY spectrum above 1 TeV.

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arXiv2006

Tools for Deconstructing Gauge Theories in AdS5

We employ analytical methods to study deconstruction of 5D gauge theories in the AdS5 background. We demonstrate that using the so-called q-Bessel functions allows a quantitative analysis of the deconstructed setup. Our study clarifies the relation of deconstruction with 5D warped theories.

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arXiv2006

Twin SUSY

We construct an extension of the MSSM in which superpartners can naturally be heavier than the electroweak scale. This ``little hierarchy'' of scales is stable because the Higgs arises as a pseudo-Nambu-Goldstone boson in the breaking of an accidental SU(4) symmetry of the Higgs sector. Supersymmetry and the global symmetry combine to forbid logarithmically divergent one-loop contributions to the Higgs mass. The accidental symmetry follows from a simple ``twin'' parity which exchanges the SU(2) sectors in the SU(3)_C x SU(2)_L x SU(2)_R x U(1)_X gauge group.

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arXiv2005

Gravity mediated supersymmetry breaking in six dimensions

We study gravity mediated supersymmetry breaking in four-dimensional effective theories derived from six-dimensional brane-world supergravity. Using the Noether method we construct a locally supersymmetric action for a bulk-brane system consisting of the minimal six-dimensional supergravity coupled to vector and chiral multiplets located at four-dimensional branes. Couplings of the bulk moduli to the brane are uniquely fixed, in particular, they are flavour universal. We compactify this system on T_2/Z_2 and derive the four-dimensional effective supergravity. The tree-level effective Kahler potential is not of the sequestered form, therefore gravity mediation may occur at tree-level. We identify one scenario of moduli stabilization in which the soft scalar masses squared are postive.

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arXiv2005

Double protection of the Higgs potential

A mechanism of double protection of the Higgs potential, by supersymmetry and by a global symmetry, is investigated in a class of supersymmetric models with the SU(3)xSU(3)xU(1) gauge symmetry. In such models the electroweak symmetry can be broken with no fine-tuning at all.

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arXiv2005

Soft Supersymmetry Breaking in KKLT Flux Compactification

We examine the structure of soft supersymmetry breaking terms in KKLT models of flux compactification with low energy supersymmetry. Moduli are stabilized by fluxes and nonperturbative dynamics while a de Sitter vacuum is obtained by adding supersymmetry breaking anti-branes. We discuss the characteristic pattern of mass scales in such a set-up as well as some features of 4D N=1 supergravity breakdown by anti-branes. Anomaly mediation is found to always give an important contribution and one can easily arrange for flavor-independent soft terms. In its most attractive realization, the modulus mediation is comparable to the anomaly mediation, yielding a quite distinctive sparticle spectrum. In addition, the axion component of the modulus/dilaton superfield dynamically cancels the relative CP phase between the contributions of anomaly and modulus mediation, thereby avoiding dangerous SUSY CP violation.

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