1,721,049 research outputs found
Uncovering quasi-degenerate Kaluza-Klein Electro-Weak gauge bosons with top asymmetries at the LHC
No full textBy exploiting the correlation between charge and spin polarisation asymmetries in t-tbar, we show that combining the two observables could identify the presence of quasi-degenerate states in a resonant signal at the LHC. As an example, we investigate experimental signatures emerging in top-antitop final states in the context of a model where the Standard Model Electro-Weak sector is allowed to propagate in large extra--dimensions of TeV-1 size while the colour sector is localised. Assuming current experimental constraints from the 7 and 8 TeV runs and taking into account the estimated top (anti-top) reconstruction efficiencies, we find that the 14 TeV upgraded LHC with the planned integrated luminosity L=100 fb-1 could access these quasi-degenerate multiple resonances and explore for the first time the rich phenomenology in the asymmetry observables. The main outcome would be having measurable quantities, complementary to the usual total and differential cross sections, capable of distinguishing a quasi-degenerate multiply resonant spectrum from a 'standard' single resonance that could present a similar signal in a bump hunt analysis
Constraining Parton Distribution Functions from neutral current Drell-Yan measurements
Full text linkWe study the cross section σ and forward-backward asymmetry (AFB) in the process pp→γ∗,Z→+- (with =e, μ) for determinations of parton distribution functions (PDFs) of the proton. We show that, once mapped in the invariant mass of the dilepton final state, M(), both observables, σ and AFB, display a statistical error which is presently competitive with that assigned to the existing PDF sets and which will rapidly become smaller than the latter as the luminosity being accumulated at Run-II of the LHC grows. This statement is applicable to both on-peak and off-peak M() regions, both (just) below and above it, thereby offering a means of constraining the quark PDFs over a sizable (x,Q2) range.</p
The four site Higgsless model at the LHC
No full textWe consider the four-site Higgsless model, which predicts the existence of four charged and two neutral extra gauge bosons, W1,2± and Z1,2. In contrast to other Higgsless models, characterized by fermiophobic extra gauge bosons, here sizeable fermion-boson couplings are allowed by the electroweak precision data. We thus analyse the prospects of detecting the new predicted particles in the mostly favored Drell-Yan channel at the LHC
Neutral current forward-backward asymmetry: from theta(W) to PDF determinations
No full textMeasurements of the forward–backward asymmetry in neutral-current Drell–Yan di-lepton production have primarily been used for determinations of the weak mixing angle θW. We observe that, unlike the case of Run-I of the Large Hadron Collider (LHC Run-I), for the first time at the LHC Run-II the reconstructed forward–backward asymmetry has the capability of placing useful constraints on the determination of the parton distribution functions (PDFs). By examining the statistical and the PDF uncertainties on the reconstructed forward–backward asymmetry, we investigate its potential for disentangling the flavour content of quark and antiquark PDFs. Access to the valence/sea u-quark and to the sea up-type antiquark PDFs, in particular, may be gained by the appropriate use of selection cuts in the rapidity of the emerging lepton pair in regions both near the Z-boson peak and away from it, in a manner complementary, though more indirect, to the case of the charged-current asymmetry. We study the extension of these results for the planned high-luminosity (HL) LHC.</p
Erratum to: Neutral current forward-backward asymmetry: from W to PDF determinations (vol 78, 663, 2018)
No full textWe submit an Erratum for our paper Eur. Phys. J. C (2018) 78: 663 (ID: EPJC-18-06-165), with title “Neutral current Forward-Backward Asymmetry:</p
Higgs physics
No full textContribution to the workshop Physics at LEP2 on theory predictions for the search for the Higgs boson at LEP2
Event Generators for WW Physics
No full textContribution to the workshop Physics at LEP2 on the status of the event generators for W-boson physics at LEP2
Standard Model processes
No full textContribution to the workshop Physics at LEP2 on the status of the theoretical calculations for a variety of Standard Model processes
- …
