119291756
Gluino Stransverse Mass
We introduce a new observable, ’gluino stransverse mass’, which is an application of the Cambridge mT2 variable to the process where gluinos are pair produced in proton-proton collision and each gluino subsequently decays into two quarks and one LSP, i.e. g̃g̃ → qqχ̃01 qqχ̃ 0 1. We show that the gluino stransverse mass can be utilized to measure the gluino mass and the lightest neutralino mass separately, and also the 1st and 2nd generation squark masses if squarks are lighter than gluino, thereby providing a good first look at the pattern of sparticle masses experimentally.
55429027
Sparticle masses from transverse mass kinks at the LHC: the case of Yukawa-unified SUSY GUTs
We explore, in a concrete example, to which extent new particle mass determinations are practicable with LHC data. Our chosen example is that of Yukawa-unified SUSY GUTs, whose viability has been recently studied for two general patterns of soft SUSY-breaking terms. We note that both patterns of SUSY spectra do not admit long decay chains, which would make it possible to determine the masses of the SUSY particles involved using endpoints or mass relations. We thus take the so-called mT2-kink method as our key strategy, since it does not rely on the presence of long decay chains. We then discuss a procedure allowing to determine the masses of the gluino, of the lightest chargino as well as of the first two neutralinos and, for the scenario where a stop is lighter than the gluino, the mass of the light stop too. Our worked example of Yukawa-unified SUSY GUTs may offer a useful playground for dealing with other theories which predict similar patterns of SUSY spectra.
119163667
MT2-reconstructed invisible momenta as spin analizers, and an application to top polarization
A bstractFull event reconstruction is known to be challenging in cases with more than one undetected final-state particle, such as pair production of two states each decaying semi-invisibly. On the other hand, full event reconstruction would allow to access angular distributions sensitive to the spin fractions of the decaying particles, thereby dissecting their production mechanism. We explore this possibility in the case of Standard-Model $ t\overline{t} $ production followed by a leptonic decay of both W bosons, implying two undetected final-state neutrinos. We estimate the t and $ \overline{t} $ momentum vectors event by event using information extracted from the kinematic variable MT2. The faithfulness of the estimated momenta to the true momenta is then tested in observables sensitive to top polarization and $ t\overline{t} $ spin correlations. Our method thereby provides a novel approach towards the evaluation of these observables, and towards testing $ t\overline{t} $ production beyond the level of the total cross section. While our discussion is confined to $ t\overline{t} $ production as a benchmark, the method is applicable to any process whose decay topology allows to construct MT2.
118657630
Transverse Mass Kink
We present a study of the collider observable mT2 applied for pair‐produced superparticles decaying to visible particles and a pair of invisible lightest supersymmetric particles (LSPs) at the LHC experiment. We also investigate the possibility to measure the top quark mass using the mT2.
119258320
Supersymmetric Higgs-portal and X-ray lines
Abstract We consider a Dirac singlet fermion as thermal dark matter for explaining the X-ray line in the context of a supersymmetric Higgs-portal model or a generalized Dirac NMSSM. The Dirac singlet fermion gets a mass splitting due to their Yukawa couplings to two Higgs doublets and their superpartners, Higgsinos, after electroweak symmetry breaking. We show that a correct relic density can be obtained from thermal freeze-out, due to the co-annihilation with Higgsinos for the same Yukawa couplings. We discuss the phenomenology of the Higgsinos in this model such as displaced vertices at the LHC.
119286463
Peccei-Quinn NMSSM in the light of 125 GeV Higgs
A bstractWe study the phenomenology of the Peccei-Quinn invariant extension of the next-to-minimal supersymmetric standard model (NMSSM) in view of the recent discovery of a 125 GeV Higgs boson. The minimal model having no quadratic and cubic terms of the NMSSM singlet field predicts a light singlino-like lightest supersymmetric particle (LSP). The model is strongly constrained by the Higgs invisible decay and the dark matter characteristic of the LSP, while some constraints can be relaxed by assuming that the saxion, the CP-even companion of the axion in the Peccei-Quinn sector, causes a late-time entropy production diluting the thermal LSP density. The collider signal of the model contains multi-jet and h/W/Z plus missing energy, which can be discovered in the early stage of the 14 TeV LHC running.
204002512
a Search for Strange B Meson in UPSILON(5S) Decay