Questions of Lorentz Invariance in Field Theories with Indefinite Metric

Lee, T. D.; Wick, G. C.

doi:10.1103/physrevd.3.1046

Cited by 50 publications

(44 citation statements)

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“…1 we clearly see that the LEP2 data provide less stringent constraints on the LW masses than the Z-pole data. 9 They show a minimum away from the SM corresponding to M 1 ! 1 and M 2 ' 2:6 TeV.…”

Section: Numerical Resultsmentioning

confidence: 98%

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Electroweak precision data and the Lee-Wick standard model

Underwood

Zwicky

2009

Phys. Rev. D

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We investigate the electroweak precision constraints on the recently proposed Lee-Wick standard model at tree level. We analyze low-energy, Z-pole (LEP1/SLC) and LEP2 data separately. We derive the exact tree-level low-energy and Z-pole effective Lagrangians from both the auxiliary field and higher derivative formulation of the theory. For the LEP2 data we use the fact that the Lee-Wick standard model belongs to the class of models that assumes a so-called ''universal'' form which can be described by seven oblique parameters at leading order in m 2 W =M 2 1;2 . At tree level we find that Y ¼ Àm 2 W =M 2 1 and W ¼ Àm 2 W =M 2 2 , where the negative sign is due to the presence of the negative norm states. All other oblique parameters ðŜ; XÞ and ðT;Û; VÞ are found to be zero. In the addendum we show how our results differ from previous investigations, where contact terms, which are found to be of leading order, have been neglected. The LEP1/SLC constraints are slightly stronger than LEP2 and much stronger than the low-energy ones. The LEP1/SLC results exclude gauge boson masses of M 1 ' M 2 $ 3 TeV at the 99% confidence level. Somewhat lower masses are possible when one of the masses assumes a large value. Loop corrections to the electroweak observables are suppressed by the standard $1=ð4Þ 2 factor and are therefore not expected to change the constraints on M1 and M 2 . This assertion is most transparent from the higher derivative formulation of the theory.

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Section: Numerical Resultsmentioning

confidence: 98%

“…(9). Since the LWSM neither violates SUð2Þ L nor custodial symmetry in the gauge boson sector the first class ðþ; ÀÞ…”

Section: Lep2 Data and The Oblique Parametersmentioning

confidence: 99%

Electroweak precision data and the Lee-Wick standard model

Underwood

Zwicky

2009

Phys. Rev. D

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“…In this model the hidden sector consists of dark fermions charged under U (1) F . As previously noted in [23], spontaneous chiral symmetry breaking can be triggered by the presence of a higher derivative kinetic term in the gauge sector, suppressed by a scale Λ, which can be interpreted as the mass scale of the associated Lee-Wick ghost [24] of the U (1) F gauge theory. The dark fermion masses M i can be dynamically generated via nonperturbative mechanism a la Nambu-Jona-Lasinio [25] as a nontrivial solution of the (finite) mass-gap equation.…”

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confidence: 83%

Dark photons and resonant monophoton signatures in Higgs boson decays at the LHC

et al. 2014

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Motivated by dark-photonγ scenarios extensively considered in the literature, we explore experimentally allowed models where the Higgs boson coupling to photon and dark photon Hγγ can be enhanced. Correspondingly, large rates for the H → γγ decay become plausible, giving rise to one monochromatic photon with E γ mH /2 (i.e., more than twice the photon energy in the rare standard-model decay H → γZ → γνν), and a similar amount of missing energy. We perform a model-independent study of this exotic resonant monophoton signature at the LHC, featuring a distinctive E γ T peak around 60 GeV, and γ + / E T transverse invariant mass ruled by mH . At parton level, we find a 5 σ sensitivity of the present LHC data set for a H → γγ branching fraction of 0.5%. Such large branching fractions can be naturally obtained in dark U (1)F models explaining the origin and hierarchy of the standard model Yukawa couplings. We urge the LHC experiments to search for this new exotic resonance in the present data set, and in future LHC runs.Introduction. Although dark matter (DM) is five times more abundant in the Universe than ordinary baryonic matter [1], its properties are yet unknown. It is plausible that the dark sector, which is weakly coupled to the standard model (SM), possesses rich internal structure and interactions. Among the most popular scenarios is the idea that the dark sector contains light or massless gauge bosons [2] that mediate long-range forces between dark particles. In cosmology the dark photons may solve the small-scale structure formation problems [3,4] and, for massless dark photons [5], predict dark discs of galaxies [6]. In astroparticle physics dark photons may induce Sommerfeld enhancement of DM annihilation cross section needed to explain the PAMELA-Fermi-AMS2 positron anomaly [7], may assist light DM annihilations to reach the phenomenologically required magnitude, and make asymmetric DM scenarios phenomenologically viable [8]. Dark/hidden photon scenarios have also been extensively considered in beyond-the-SM frameworks in particle physics [9][10][11][12][13][14][15].Recently, a new paradigm has been proposed for generating exponentially spread SM Yukawa couplings from unbroken U (1) F quantum numbers in the dark sector [16]. In this approach, nonperturbative flavor-and chiral-symmetry breaking is transferred from the dark to visible sector via heavy scalar messenger fields [16,17] In this work we show that, in the unbroken dark U (1) scenarios, the Higgs-boson two-body decay H → γγ to one photon γ and one dark photonγ can be enhanced despite existing constraints, providing a very distinctive NP signature of a single photon plus missing energy at the Higgs resonance. If this signature will be discovered at the LHC, CP invariance will imply the spin-1 nature of the missing energy, excluding axions or other ultralight scalar particles.Monophoton plus / E T signatures have been used by the LHC experiments to search for NP scenarios such as extra dimensions, supersymmetry, DM pair production [19], and SM con...

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“…As it is expected, the presence of this higher-derivative operator introduce ghost states that, in principle, could jeopardize the unitarity of the model (since the energy wouldn't be bounded from below). The problems of non-unitarity concerning higher-derivative theories has been extensively studied in the context of Lee and Wick theories, and many solutions for this issue has been proposed along the last decades [8][9][10][11][12]. Although it was recently shown, for the Myers-Pospelov model, that in electron-positron and Compton scattering there is no contribution of the ghost states [13,14], we present here a alternative approach to the subject of tree-level unitarity.…”

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confidence: 99%

Unitarity and nonrelativistic potential energy in a higher-order Lorentz symmetry breaking electromagnetic model

Scatena

Turcati

2014

Phys. Rev. D

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The Lorentz-violating model proposed by Myers and Pospelov suffers from a higher-derivative pathology due to a dimension-five operator. In particular, its electromagnetic sector exhibits a spectrum which contains, in addition to an expected massless photon, ghost contributions that could (in principle) spoil the unitarity of the model. We find that unitarity at tree level can be assured for pure spacelike, timelike, and lightlike background four-vectors (the last two under restrictions upon the allowed momenta). We then analyze the nonrelativistic interparticle potential energy behavior for different background fourvectors and compare to the usual Coulomb potential.

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Questions of Lorentz Invariance in Field Theories with Indefinite Metric

Cited by 50 publications

References 5 publications

Electroweak precision data and the Lee-Wick standard model

Electroweak precision data and the Lee-Wick standard model

Dark photons and resonant monophoton signatures in Higgs boson decays at the LHC

Unitarity and nonrelativistic potential energy in a higher-order Lorentz symmetry breaking electromagnetic model

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