Flavor violation and extra dimensions

The "anarchic" Randall-Sundrum model of flavor is a low energy solution to both the electroweak hierarchy and flavor problems. Such models have a warped, compact extra dimension with the standard model fermions and gauge bosons living in the bulk, and the Higgs living on or near the TeV brane. In this paper we consider bounds on these models set by lepton flavor violation constraints. We find that loop-induced decays of the form l → l ′ γ are ultraviolet sensitive and uncalculable when the Higgs field is localized on a four-dimensional brane; this drawback does not occur when the Higgs field propagates in the full five-dimensional space-time. We find constraints at the few TeV level throughout the natural range of parameters, arising from µ − e conversion in the presence of nuclei, rare µ decays, and rare τ decays. A "tension" exists between loopinduced dipole decays such as µ → eγ and tree-level processes such as µ − e conversion; they have opposite dependences on the five-dimensional Yukawa couplings, making it difficult to decouple flavor-violating effects. We emphasize the importance of the future experiments MEG and PRIME. These experiments will definitively test the Randall-Sundrum geometric origin of hierarchies in the lepton sector at the TeV-scale.

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“…With a brane Higgs field, f = √ 2kπr c ∼ O (10). A plot of f for a bulk Higgs field is shown in Fig.…”

Section: Tri-lepton Decays and µ − E Conversionmentioning

confidence: 99%

Probing the Randall-Sundrum geometric origin of flavor with lepton flavor violation

2006

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“…The presence of KK-towers for charged and neutral CP-odd Higgs bosons provides a concrete example of this. The phenomenology of KK-excitations has been studied in great detail in recent times which covers its implications at colliders [3,4,5,6,7,8,9,10,11,12,13,14,15,16], in electroweak/flavour sector via various low-energy observables [17,18,19,20,21,22,23,24,25,26,27,28] and for dark matter/cosmology [5,13,29,30,31,32,33,34,35,36,37,38,39,40] In MUED there are only two extra free parameters when compared to the SM. These are the radius of compactification R (or, alternately R −1 , the scale of compactification) and the cutoff scale Λ of the theory.…”

Section: Introductionmentioning

confidence: 99%

Search for Higgs bosons of the universal extra dimensions at the large Hadron collider

Bandyopadhyay

Bhattacherjee

Datta

2010

J. High Energ. Phys.

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The Higgs sector of the Universal Extra Dimensions (UED) has a rather involved setup. With one extra space dimension, the main ingredients to the construct are the higher Kaluza-Klein (KK) excitations of the Standard Model Higgs boson and the fifth components of the gauge fields which on compactification appear as scalar degrees of freedom and can mix with the former thus leading to physical KK-Higgs states of the scenario. In this work, we explore in detail the phenomenology of such a Higgs sector of the UED with the Large Hadron Collider (LHC) in focus. We work out relevant decay branching fractions involving the KK-Higgs excitations. Possible production modes of the KK-Higgs bosons are then discussed with an emphasis on their associated production with the third generation KK-quarks and that under the cascade decays of strongly interacting UED excitations which turn out to be the only phenomenologically significant modes. It is pointed out that the collider searches of such Higgs bosons face generic hardship due to soft end-products which result from severe degeneracies in the masses of the involved excitations in the minimal version of the UED (MUED). Generic implications of either observing some or all of the KK-Higgs bosons at the LHC are discussed.

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“…In many extra dimensional models (see, for example Ref. [16]), a successful localization of the SM fermions to reproduce the fermion mass heirarchy can generate dangerous FCNC processes. In the split fermion scenario, Lillie and Hewett in Ref.…”

Section: Fcnc Constraintsmentioning

confidence: 99%

Fermion mass hierarchy and phenomenology in the 5D Domain Wall Standard Model

Okada

Raut

Villalba

2019

J. High Energ. Phys.

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We have recently proposed a setup of the "Domain-Wall Standard Model" in 5D spacetime, where all the Standard Model (SM) fields are localized in certain domains of the extra 5th dimension. Utilizing this setup, we attempt to solve the fermion mass hierarchy problem of the SM. The mass hierarchy can be naturally explained by suitably distributing the fermions in different positions along the extra dimension. Due to these different localization points, the effective 4D gauge couplings of Kaluza-Klein (KK) mode gauge bosons to the SM fermions become non-universal. As a result, our model is severely constrained by the Flavor Changing Neutral Current (FCNC) measurements. We find two interesting cases in which our model is phenomenologically viable: (1) the KK-mode of the SM gauge bosons are extremely heavy and unlikely to be produced at the Large Hadron Collider (LHC), while future FCNC measurements can reveal the existence of these heavy modes.(2) the width of the localized SM fermions is very narrow, leading to almost universal 4D KK-mode gauge couplings. In this case, the FCNC constraints can be easily avoided even if a KK gauge boson mass lies at the TeV scale. Such a light KK gauge boson can be searched at the LHC in the near future.

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Flavor violation and extra dimensions

Cited by 34 publications

References 57 publications

Probing the Randall-Sundrum geometric origin of flavor with lepton flavor violation

Probing the Randall-Sundrum geometric origin of flavor with lepton flavor violation

Search for Higgs bosons of the universal extra dimensions at the large Hadron collider

Fermion mass hierarchy and phenomenology in the 5D Domain Wall Standard Model

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