Search results for "ROWE"
showing 10 items of 842 documents
LHC sensitivity to singly charged scalars decaying into electrons and muons
2020
Current LHC searches for nonsupersymmetric singly charged scalars, based on two-Higgs-doublet models, in general, focus the analysis in third-generation fermions in the final state. However, singly charged scalars in alternative extensions of the scalar sector involve Yukawa couplings not proportional to the mass of the fermions. Assuming the scalar decays into electrons and muons, it can manifest cleaner experimental signatures. In this paper, we suggest that a singly charged scalar singlet, with electroweak production, can start to be probed in the near future with dedicated search strategies. Depending on the strength of the Yukawa couplings, two independent scenarios are considered: dir…
Observation of Electroweak Production of a Same-Sign W Boson Pair in Association with Two Jets in pp Collisions at s=13 TeV with the ATLAS Detector
2019
This Letter presents the observation and measurement of electroweak production of a same-sign W boson pair in association with two jets using 36.1 fb^{-1} of proton-proton collision data recorded at a center-of-mass energy of sqrt[s]=13 TeV by the ATLAS detector at the Large Hadron Collider. The analysis is performed in the detector fiducial phase-space region, defined by the presence of two same-sign leptons, electron or muon, and at least two jets with a large invariant mass and rapidity difference. A total of 122 candidate events are observed for a background expectation of 69±7 events, corresponding to an observed signal significance of 6.5 standard deviations. The measured fiducial s…
Neutron-skin effect and centrality dependence of high-pT observables in nuclear collisions
2016
We report on our studies of the neutron-skin effects in high-pT observables at the LHC. We study the impact of the neutron-skin effect on the centrality dependence of inclusive direct photon, highpT hadron and W± production in nuclear collisions at the LHC. The neutron-skin effect refers to the observation that in spherical heavy nuclei, the tail of the neutron distribution extends farther than the distribution of protons, which can affect observables sensitive to electroweak phenomena in very peripheral collisions. We quantify this effect for direct photons, charged hadrons and W bosons as a function of the collision centrality. In the case of direct photons we find that it will be difficu…
Review of single vector boson production in pp collisions at $$\sqrt{s} = 7$$ s = 7 TeV
2014
This review summarises the main results on the production of single vector bosons in the Standard Model, both inclusively and in association with light- and heavy-flavour jets, at the Large Hadron Collider in proton–proton collisions at a centre-of-mass energy of $$7\,{\mathrm {\ TeV}}$$ . The general purpose detectors at this collider, ATLAS and CMS, each recorded an integrated luminosity of $${\approx } 40\,\mathrm{pb^{-1}}$$ and $$5\,\mathrm{fb^{-1}}$$ in the years 2010 and 2011, respectively. The corresponding data offer the unique possibility to precisely study the properties of the production of heavy vector bosons in a new energy regime. The accurate understanding of the Standard Mod…
Natural stabilization of the Higgs boson’s mass and alignment
2019
Current data from the LHC indicate that the 125 GeV Higgs boson, $H$, is either the single Higgs of the Standard Model or, to a good approximation, an "aligned Higgs". We propose that $H$ is the pseudo-Goldstone dilaton of Gildener and Weinberg. Models based on their mechanism of scale symmetry breaking can naturally account for the Higgs boson's low mass and aligned couplings. We conjecture that they are the only way to achieve a "Higgslike dilaton" that is actually the Higgs boson. These models further imply the existence of additional Higgs bosons in the vicinity of 200 to about 550 GeV. We illustrate our proposal in a version of the two-Higgs-doublet model of Lee and Pilaftsis. Our vers…
Higgs Pair Production as a Signal of Enhanced Yukawa Couplings
2018
We present a non-trivial correlation between the enhancement of the Higgs-fermion couplings and the Higgs pair production cross section in two Higgs doublet models with a flavour symmetry. This symmetry suppresses flavour-changing neutral couplings of the Higgs boson and allows for a partial explanation of the hierarchy in the Yukawa sector. After taking into account the constraints from electroweak precision measurements, Higgs coupling strength measurements, and unitarity and perturbativity bounds, we identify an interesting region of parameter space leading to enhanced Yukawa couplings as well as enhanced di-Higgs gluon fusion production at the LHC reach. This effect is visible in both t…
Search for the Standard Model Higgs Boson in theH→WW→lνq′q¯Decay Channel
2011
We present a search for the standard model Higgs boson (H) in ppbar collisions at sqrt{s}=1.96 TeV in events containing a charged lepton (ell), missing transverse energy, and at least two jets, using 5.4 fb^-1 of integrated luminosity recorded with the D0 detector at the Fermilab Tevatron Collider. This analysis is sensitive primarily to Higgs bosons produced through the fusion of two gluons or two electroweak bosons, with subsequent decay H->WW->ell+nu+q'qbar, where ell is an electron or muon. The search is also sensitive to contributions from other production channels, such as WH->ell+nu+bbbar In the absence of signal, we set limits at the 95% C.L. on the cross section for H production si…
Tau leptonic branching ratios
1996
A sample of 62249 tau-pair events is selected from data taken with the ALEPH detector in 1991, 1992 and 1993. The measurement of the branching fractions for tau decays into electrons and muons is presented with emphasis on the study of systematic effects from selection, particle identification and decay classification. The results obtained are: B-e=17.79+/-0.12(stat)+/-0.06(syst)(%) and B-mu=17.31+/-0.11(stat)+/-0.05(syst)(%). Combined with the most recent ALEPH determination of the tau lifetime, these results provide a relative measurement of the leptonic couplings in the weak charged current for transverse W bosons: g(mu)/g(e)=1.0002+/-0.0051 and g(tau)/g(mu)=0.9943+/-0.0065. RI ANTONELLI…
(g−2)e,μ in an extended inverse type-III seesaw model
2021
There has been a longstanding discrepancy between the experimental measurements of the electron and muon anomalous magnetic moments and their predicted values in the Standard Model. This is particularly relevant in the case of the muon $g\ensuremath{-}2$, which has attracted a remarkable interest in the community after the long-awaited announcement of the first results by the Muon $g\ensuremath{-}2$ collaboration at Fermilab, which confirms a previous measurement by the E821 experiment at Brookhaven and enlarges the statistical significance of the discrepancy, now at $4.2\ensuremath{\sigma}$. In this paper we consider an extension of the inverse type-III seesaw with a pair of vectorlike lep…
The coannihilation codex
2015
We present a general classification of simplified models that lead to dark matter (DM) coannihilation processes of the form DM + X $\rightarrow$ SM$_1$ + SM$_2$, where X is a coannihilation partner for the DM particle and SM$_1$, SM$_2$ are Standard Model fields. Our classification also encompasses regular DM pair annihilation scenarios if DM and X are identical. Each coannhilation scenario motivates the introduction of a mediating particle M that can either belong to the Standard Model or be a new field, whereby the resulting interactions between the dark sector and the Standard Model are realized as tree-level and dimension-four couplings. We construct a basis of coannihilation models, cl…