An unambiguous search for a light Higgs boson

Davier, M.; Ngoc, H. Nguyên

doi:10.1016/0370-2693(89)90174-3

Cited by 268 publications

(267 citation statements)

References 16 publications

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“…Correspondingly the resulting constraint applies to ξ e only. According to [31] life times τ A in the range 5 · 10 −12 s τ A 2 · 10 −9 s are ruled out for M A ∼ 17 − 18 MeV. This has already been translated into constraints on a reduced pseudoscalar-fermion Yukawa coupling C Aff in [13], where C Aff = ξ e in our notation.…”

Section: Jhep11(2016)039mentioning

confidence: 86%

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Possible explanation of the electron positron anomaly at 17 MeV in 8 Be transitions through a light pseudoscalar

Ellwanger

Moretti

2016

J. High Energ. Phys.

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Abstract:We estimate the values of Yukawa couplings of a light pseudoscalar A with a mass of about 17 MeV, which would explain the 8 Be anomaly observed in the Atomki pair spectrometer experiment. The resulting couplings of A to up and down type quarks are about 0.3 times the coupling of the standard Higgs boson. Then constraints from K and B decays require that loop contributions to flavour changing vertices cancel at least at the 10% level. Constraints from beam dump experiments require the coupling of A to electrons to be larger than about 4 times the coupling of the standard Higgs boson, leading to a short enough A life time consistent with an explanation of the anomaly.

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Section: Jhep11(2016)039mentioning

confidence: 86%

“…First, an electron beam dump on lead experiment was conducted in Orsay [31] with the aim to search for light scalar or pseudoscalar Higgs…”

Section: Jhep11(2016)039mentioning

confidence: 99%

Possible explanation of the electron positron anomaly at 17 MeV in 8 Be transitions through a light pseudoscalar

Ellwanger

Moretti

2016

J. High Energ. Phys.

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“…5. The scalar mediator is constrained by direct production in beam dump experiments [47][48][49][50], BaBar [51], and supernovae [52][53][54][55][56][57]. Since φ couples to electrons but not neutrinos, it modifies their relative temperatures after the weak interactions decouple, changing the effective number of neutrinos, N eff [58].…”

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confidence: 99%

Fourth Exception in the Calculation of Relic Abundances

2017

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We propose that the dark matter abundance is set by the decoupling of inelastic scattering instead of annihilations. This coscattering mechanism is generically realized if dark matter scatters against states of comparable mass from the thermal bath. Coscattering points to dark matter that is exponentially lighter than the weak scale and has a suppressed annihilation rate, avoiding stringent constraints from indirect detection. Dark matter upscatters into states whose late decays can lead to observable distortions to the blackbody spectrum of the cosmic microwave background.Introduction: Dark Matter (DM) constitutes most of the matter in our Universe, but its origin is unknown. One of the most attractive possibilities is that DM starts in thermal equilibrium in the early Universe, and its abundance is set once its annihilations become slower than the expansion rate. This framework is insensitive to initial conditions and has the further appeal of tying the DM abundance to its (potentially observable) interactions.The most widely considered possibility is that 2-to-2 annihilations to Standard Model (SM) particles set the DM relic density. This is known as the Weakly Interacting Massive Particle (WIMP) paradigm [1-4] and points to DM particles with weak scale masses and crosssections. This theoretical framework has had considerable impact shaping experimental searches for DM.However it has long been appreciated that simple variations to the cosmology of thermal relics can have dramatic consequences. In a seminal paper, Ref.[5] enumerates three "exceptions" to thermal relic cosmology: (1) mutual annihilations of multiple species (coannihilations), (2) annihilations into heaver states (forbidden channels), and (3) annihilations near a pole in the cross section. These exceptions lead to phenomenology that can differ significantly from standard WIMPs (see for example [11][12][13]34]), while sharing their appealing theoretical features.In this letter, we introduce a fourth exception. Like Ref.[5], we assume DM begins in thermal equilibrium, has its number diluted through 2-to-2 annihilations, and has a temperature that tracks the photon temperature (for studies that relax at least one of these assumptions see for example Refs. [14][15][16][17][18][19][20][21][22][23][24][25][26][27]). We consider the presence of two states charged under the symmetry that stabilizes DM: χ and ψ, where m χ < m ψ and χ is DM. We assume that χ annihilations are suppressed, and two processes are active:

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“…This boson should be able to couple with strength ε 2 e to ordinary particles by means of kinetic mixing with the SM hypercharge field [27][28][29][30][31][32][33][34]. A tipical value for the kinetic mixing parameter ε is expected to be of the order 10 −3 [27,28,33,[35][36][37][38] so that observable effects can be induced at e + e − colliders [35,[39][40][41] and fixed target [42][43][44] or beam dump experiments [45][46][47][48][49].…”

Section: Introductionmentioning

confidence: 99%

Dark Forces at KLOE/KLOE-2

Curciarello

2014

EPJ Web of Conferences

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Abstract. Searches for dark matter particles in the GeV mass range and for dark forces are strongly motivated by the numerous striking astrophysical observations recently reported by many experiments. Flavor factories, like the Frascati Φ-factory DAΦNE, are particularly suited to search for the light gauge vector boson, called U boson, which is thought to mediate an unknown interaction between hypothetical dark matter particles. By using the KLOE detector, limits on U boson coupling factor ε 2 of the order of 10 −5 ÷ 10 −7 have been set through the study of the φ Dalitz decay, the Higgsstrahlung process and Uγ events. New experiments with the upgraded KLOE detector and the increased luminosity of DAΦNE are expected to improve the already set upper limits by a factor of two or better. a

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An unambiguous search for a light Higgs boson

Cited by 268 publications

References 16 publications

Possible explanation of the electron positron anomaly at 17 MeV in 8 Be transitions through a light pseudoscalar

Possible explanation of the electron positron anomaly at 17 MeV in 8 Be transitions through a light pseudoscalar

Fourth Exception in the Calculation of Relic Abundances

Dark Forces at KLOE/KLOE-2

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