Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userMeasuring the CP property of Higgs coupling to tau leptons in the VBF channel at the LHC
159
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We study the prospects of measuring the CP property of the Higgs ($h$) coupling to tau leptons using the vector boson fusion (VBF) production mode at the high-luminosity LHC. Utilizing the previously proposed angle between the planes spanned by the momentum vectors of the $(pi^+pi^0)$ and $(pi^- pi^0)$ pairs originating in $tau^pm$ decays as the CP-odd observable, we perform a detailed Monte Carlo analysis, taking into account the relevant standard model backgrounds, as well as detector resolution effects. We find that excluding a pure CP-odd coupling hypothesis requires $mathcal{O}(400 {~rm fb}^{-1})$ luminosity at the 14 TeV LHC, and values of the CP-mixing angle larger than about $25^circ$ can be excluded at $95%$ confidence level using $3 {~rm ab}^{-1}$ data. It is observed that the uncertainty in the angular resolution of the neutral pion momenta does not constitute a significant hurdle. Achieving a signal to background ratio ($S/B$) close to one, while keeping a high enough signal yield required to study the angular distributions selects out VBF as a promising mode to probe the CP nature of the $htautau$ coupling, with gluon fusion suffering from a low $S/B$, and the $W^pm h/Zh$ mode (with leptonically decaying $W^pm /Z$) having a much smaller signal rate.
rate research
Read More
The search for a new source of CP violation is one of the most important endeavors in particle physics. A particularly interesting way to perform this search is to probe the CP phase in the $htautau$ coupling, as the phase is currently completely unconstrained by all existing data. Recently, a novel variable $Theta$ was proposed for measuring the CP phase in the $htautau$ coupling through the $tau^pm to pi^pm pi^0 u$ decay mode. We examine two crucial questions that the real LHC detectors must face, namely, the issue of neutrino reconstruction and the effects of finite detector resolution. For the former, we find strong evidence that the collinear approximation is the best for the $Theta$ variable. For the latter, we find that the angular resolution is actually not an issue even though the reconstruction of $Theta$ requires resolving the highly collimated $pi^pm$s and $pi^0$s from the $tau$ decays. Instead, we find that it is the missing transverse energy resolution that significantly limits the LHC reach for measuring the CP phase via $Theta$. With the current missing energy resolution, we find that with $sim 1000,textrm{fb}^{-1}$ the CP phase hypotheses $Delta = 0^circ$ (the standard model value) and $Delta = 90^circ$ can be distinguished, at most, at the 95% confidence level.
We propose a new dihedral angle observable to measure the CP property of the interaction of top quark and Higgs boson in the $tbar{t}H$ production at the 14~TeV LHC. We consider two decay modes of the Higgs boson, $Hto bbar{b}$ and $Hto gammagamma$ and show that the dihedral angle distribution is able to distinguish the CP-even and the CP-odd hypothesis at 95% confidence level with an integrated luminosity of $sim 180~{rm fb}^{-1}$.
In phenomenological preparation for new measurements one searches for the carriers of quality signatures. Often, the first approach quantities may be difficult to measure or to provide sufficiently precise predictions for comparisons. Complexity of necessary details grow with precision. To achieve the goal one can not break the theory principles, and take into account effects which could be ignored earlier. Mixed approach where dominant effects are taken into account with intuitive even simplistic approach was developed. Non dominant corrections were controlled with the help of Monte Carlo simulations. Concept of Optimal Variables was successfully applied for many measurements. New techniques, like Machine Learning, offer solutions to exploit multidimensional signatures. Complementarity of these new and old approaches is studied for the example of Higgs Boson CP-parity measurements in H to tau^+tau^-, tau^pm to nu (3pi)^pm cascade decays.
In the Standard Model, the Higgs boson is a CP even state with CP conserving couplings; any deviations from this would be a sign of new physics. These CP properties can be probed by measuring Higgs decays to tau lepton pairs: the transverse correlation between the tau spins depends on CP. This paper develops such an analysis, using full simulation of signal and background events in the International Large Detector concept for the International Linear Collider. We consider Higgs-strahlung events e+ e- -> Z H) in which the Z boson decays to electrons, muons, or hadrons, and the Higgs boson decays to $tau$ leptons, which then decay either to (pi+ nu) or (pi+ pi0 nu). Assuming 2 ab^{-1} of integrated luminosity at a center-of-mass energy of 250~GeV, the mixing angle psi_CP between even and odd CP components of the tau pair from Higgs boson decays can be measured to a precision of 75~mrad (4.3 deg).
We study the potential of the h_1 -> a_1 a_1 -> 4 tau signal from the lightest scalar (h_1) and pseudoscalar (a_1) Higgs bosons to cover the parameter space of the Next-to-Minimal Supersymmetric Standard Model (NMSSM) at the Large Hadron Collider (LHC). We exploit a 2 mu + 2 jets signature from four taus decays (accompanied by missing transverse energy), resorting to both Higgs-strahlung (HS), by triggering on leptonic W^pm decays, and Vector Boson Fusion (VBF), by triggering on two same sign non-isolated muons.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
