Probing the light pseudoscalar window

Anderson, David L.; Carone, Christopher D.; Sher, Marc

doi:10.1103/physrevd.67.115013

Cited by 21 publications

(39 citation statements)

References 37 publications

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“…Such an analysis was presented in Refs. [57], [58] and [64]. It was found that the low-energy data still leave open a small window for the existence of a CP-odd scalar A with a mass as light as m A < 0.2 GeV [57].…”

Section: Decays Involving Scalarsmentioning

confidence: 99%

New Physics Effects in Rare Z Decays

Pérez

Tavares‐Velasco

Toscano

2004

Int. J. Mod. Phys. A

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Virtual effects induced by new physics in rare Z decays are reviewed. Since the expected sensitivity of the giga-Z linear collider is of the order of 10 −8 , we emphasize the importance of any new physics effect that gives a prediction above this limit. It is also pointed out that an improvement on the known experimental constraints on rare Z decays will provide us with a critical test of the validity of the standard model at the loop level.

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Section: Decays Involving Scalarsmentioning

confidence: 99%

New Physics Effects in Rare Z Decays

Pérez

Tavares‐Velasco

Toscano

2004

Int. J. Mod. Phys. A

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“…As pointed out in Refs. [6,7], this particle has a very interesting phenomenology if its mass is below 200 MeV.We are interested in studying some phenomenological implications of LFV transitions mediated by a very light pseudoscalar boson φ, with 2m e < m φ < m µ . We will focus on the three-body transitions l i → l j γγ and l i → l j e + e − , with l i = µ, τ and l j = e, µ.…”

mentioning

confidence: 99%

“…As pointed out in Refs. [6,7], this particle has a very interesting phenomenology if its mass is below 200 MeV.…”

mentioning

confidence: 99%

Implications of a very light pseudoscalar boson on lepton flavor violation

2005

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A long-lived very light pseudoscalar boson would favor lepton flavor violating transitions of charged leptons. Its implications on the li → ljγγ, and li → lje + e − transitions are investigated. Assuming that 2me < m φ < mµ, it is found that the inequality B(li → ljγγ) < B(li → lj e + e − ) is hold. The experimental constraints on the decays li → ljγ, li → ljl k l k , and li → ljγγ are used to bound the φlilj couplings. PACS numbers: 12.60.Fr,14.80.Bn,11.30.Fs In the standard model (SM) the couplings of the Higgs boson to the remaining massive particles are thoroughly determined, which should be considered an outstanding feature of the model. This allowed the CERN large electron positron (LEP) collider to conclude its operative stage with a significantly strong lower bound on the Higgs boson mass of around 115 GeV [1]. However, as long as additional scalars are included in the theory, the Higgs boson masses become more difficult to bound due to the proliferation of free parameters. The bonus is the appearance of interesting new physics effects such as lepton flavor violating (LFV) and flavor changing neutral currents (FCNC) transitions, which can be mediated by the new Higgs bosons at the tree level. In particular, there are well motivated theoretical arguments that favor the existence of a very light scalar or pseudoscalar particle, which would have remained undetected so far because it would interact very weakly with ordinary matter. Since the Higgs boson masses are typically of the same order of the Fermi scale, extended scalar sectors do not lead automatically to the presence of light scalars, unless an unnatural fine tuning is implemented between all the parameters of the Higgs potential. However, an exception occurs if the theory possesses an approximate global symmetry. If such a symmetry exits and is spontaneously broken, a massless Goldstone boson arises, but if it is only approximate, a massive state arises, which is naturally light. This symmetry is only approximate because a small explicit symmetry breaking can be introduced in the classical Lagrangian or generated through quantum effects such as anomalies. The most common example is the axion . In this case, the Higgs potential possesses an exact global U (1) × U (1) symmetry in the limit of vanishing λ 5 . As pointed out in Refs. [6,7], this particle has a very interesting phenomenology if its mass is below 200 MeV.We are interested in studying some phenomenological implications of LFV transitions mediated by a very light pseudoscalar boson φ, with 2m e < m φ < m µ . We will focus on the three-body transitions l i → l j γγ and l i → l j e + e − , with l i = µ, τ and l j = e, µ. Although Higgs-mediated LFV effects have long attracted considerable attention [8,9], the current evidences of nonzero mass for the neutrinos [10] has renewed the interest in this issue, and particularly in the potential role that spin zero particles may play [11,12]. In our case, the key ingredient is the φ mass range, which imposes severe kinematical restrictions on the...

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“…This then leads to spacetime metric of the form g µν = η µν + h µν + q µν , where η µν = diag(−1, 1, 1, 1) is the background Minkowski metric, and the perturbation orders for h µν and q µν are considered to start from the first and second orders, respectively. It is important to note that for the perturbative metric expansion to be physically consistent, the energy density of the gravitational source must be below the Planck scale [18].…”

Section: Propagation Of Bosonic Fields In Fluctuating Spacetimementioning

confidence: 99%

Spacetime foam induced collective bundling of intense fields

Oniga¹,

Wang²

2016

Phys. Rev. D

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The influence of spacetime foam on a broad class of bosonic fields with arbitrary numbers of particles in the low-energy regime is investigated. Based on a recently formulated general description of open quantum gravitational systems, we analyze the propagation of scalar, electromagnetic, and gravitational waves on both long and short time scales with respect to their mean frequencies. For the long time propagation, the Markov approximation that neglects the effects of initial conditions of these waves is employed. In this case, despite intuitively expected decoherence and dissipation from the noisy spacetime, we show that such phenomena turn out to be completely suppressed for scalar bosons, photons, and gravitons, which are coupled to gravity but otherwise free. The short time effects are then recovered through the transient nonMarkovian evolution. Focusing on scalar bosons in initially incoherent states, we find that the resulting quantum dissipation depends strongly on the distribution of the particle momentum states. We further identify a hitherto undiscovered collective antidissipation mechanism for a large number of particles. The surprising new effect tends to "bundle" identical particles within sharply distributed momentum states having a width inversely proportional to the particle number due to the thermal fluctuations, or its square root due to the vacuum fluctuations of spacetime.

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Probing the light pseudoscalar window

Cited by 21 publications

References 37 publications

New Physics Effects in Rare Z Decays

New Physics Effects in Rare Z Decays

Implications of a very light pseudoscalar boson on lepton flavor violation

Spacetime foam induced collective bundling of intense fields

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