Search results for "Dark matter"
showing 10 items of 627 documents
Search for dark matter produced in association with a Higgs boson decaying to two bottom quarks inppcollisions ats=8 TeVwith the ATLAS detector
2016
This article reports on a search for dark matter pair production in association with a Higgs boson decaying to a pair of bottom quarks, using data from 20.3 fb(-1) of pp collisions at a center-of-m ...
Dark matter in the Sun: scattering off electrons vs nucleons
2017
The annihilation of dark matter (DM) particles accumulated in the Sun could produce a flux of neutrinos, which is potentially detectable with neutrino detectors/telescopes and the DM elastic scattering cross section can be constrained. Although the process of DM capture in astrophysical objects like the Sun is commonly assumed to be due to interactions only with nucleons, there are scenarios in which tree-level DM couplings to quarks are absent, and even if loop-induced interactions with nucleons are allowed, scatterings off electrons could be the dominant capture mechanism. We consider this possibility and study in detail all the ingredients necessary to compute the neutrino production rat…
Higgs in space!
2010
We consider the possibility that the Higgs can be produced in dark matter annihilations, appearing as a line in the spectrum of gamma rays at an energy determined by the masses of the WIMP and the Higgs itself. We argue that this phenomenon occurs generally in models in which the the dark sector has large couplings to the most massive states of the SM and provide a simple example inspired by the Randall-Sundrum vision of dark matter, whose 4d dual corresponds to electroweak symmetry-breaking by strong dynamics which respect global symmetries that guarantee a stable WIMP. The dark matter is a Dirac fermion that couples to a Z' acting as a portal to the Standard Model through its strong coupl…
Search for light resonances decaying to boosted quark pairs and produced in association with a photon or a jet in proton–proton collisions at s=13TeV…
2019
This Letter presents a search for new light resonances decaying to pairs of quarks and produced in association with a high- pT photon or jet. The dataset consists of proton–proton collisions with an integrated luminosity of 36.1 fb −1 at a centre-of-mass energy of s=13 TeV recorded by the ATLAS detector at the Large Hadron Collider. Resonance candidates are identified as massive large-radius jets with substructure consistent with a particle decaying into a quark pair. The mass spectrum of the candidates is examined for local excesses above background. No evidence of a new resonance is observed in the data, which are used to exclude the production of a lepto-phobic axial-vector Z′ boson.
Quark mixing in the discrete dark matter model
2011
We consider a model in which dark matter is stable as it is charged under a Z2 symmetry that is residual after an A4 flavour symmetry is broken. We consider the possibility to generate the quark masses by charging the quarks appropriately under A4. We find that it is possible to generate the CKM mixing matrix by an interplay of renormalisable and dimension-six operators. In this set-up, we predict the third neutrino mixing angle to be large and the dark matter relic density to be in the correct range. However, low energy observables - in particular meson-antimeson oscillations - strongly limit the available parameter space.
Stability of dark matter from the D4×Z2f flavor group
2011
Abstract We study a model based on the dihedral group D 4 in which the dark matter is stabilized by the interplay between a remnant Z 2 symmetry, of the same spontaneously broken non-abelian group, and an auxiliary Z 2 f introduced to eliminate unwanted couplings in the scalar potential. In the lepton sector the model is compatible with normal hierarchy only and predicts a vanishing reactor mixing angle, θ 13 = 0 . Since m ν 1 = 0 , we also have a simple prediction for the effective mass in terms of the solar angle: | m β β | = | m ν 2 | sin 2 θ ⊙ ∼ 10 − 3 eV . There also exists a large portion of the model parameter space where the upper bounds on lepton flavor violating processes are not …
The $Z$ boson in the Framed Standard Model
2018
The framed standard model (FSM), constructed initially for explaining the existence of three fermion generations and the hierarchical mass and mixing patterns of quarks and leptons, suggests also a "hidden sector" of particles including some dark matter candidates. It predicts in addition a new vector boson $G$, with mass of order TeV, which mixes with the $\gamma$ and $Z$ of the standard model yielding deviations from the standard mixing scheme, all calculable in terms of a single unknown parameter $m_G$. Given that standard mixing has been tested already to great accuracy by experiment, this could lead to contradictions, but it is shown here that for the three crucial and testable cases s…
Nonstandard Yukawa couplings and Higgs portal dark matter
2015
We study the implications of non-standard Higgs Yukawa couplings to light quarks on Higgs-portal dark matter phenomenology. Saturating the present experimental bounds on up-quark, down-quark, or strange-quark Yukawa couplings, the predicted direct dark matter detection scattering rate can increase by up to four orders of magnitude. The effect on the dark matter annihilation cross section, on the other hand, is subleading unless the dark matter is very light -- a scenario that is already excluded by measurements of the Higgs invisible decay width. We investigate the expected size of corrections in multi-Higgs-doublet models with natural flavor conservation, the type-II two-Higgs-doublet mode…
Accommodating three low-scale anomalies (g-2, Lamb shift, and Atomki) in the framed standard model
2019
The framed Standard Model (FSM) predicts a [Formula: see text] boson with mass around 20 MeV in the “hidden sector,” which mixes at tree level with the standard Higgs [Formula: see text] and hence acquires small couplings to quarks and leptons which can be calculated in the FSM apart from the mixing parameter [Formula: see text]. The exchange of this mixed state [Formula: see text] will contribute to [Formula: see text] and to the Lamb shift. By adjusting [Formula: see text] alone, it is found that the FSM can satisfy all present experimental bounds on the [Formula: see text] and Lamb shift anomalies for [Formula: see text] and [Formula: see text], and for the latter for both hydrogen and …
Dark matter searches using accelerometer-based networks
2021
Quantum science and technology 6(3), 034004 (2021). doi:10.1088/2058-9565/abef4f