Search results for "missing"
showing 10 items of 174 documents
New Higgs Signatures in Supersymmetry with Spontraneously Broken R Parity"
1992
Higgs production from $Z$ decay in supersymmetry with spontaneous broken R parity proceeds mostly by the Bjorken process as in the standard model. However, the corresponding production rates can be weaker than in the standard model (SM), especially in the low mass region. This will substantially weaken the Higgs boson mass limits derived from LEP1. More strikingly, the main Higgs decay channel is "invisible", over most of the mass range accessible to LEP1, leading to events with large missing energy carried by majorons. This possibility should be taken into account in the planning of Higgs boson search strategies not only at LEP but also at high energy supercolliders.
C(,pn) photon asymmetry for Eγ=180–340 MeV
1999
The photon asymmetry (Σ) of the 12C(,pn) reaction has been measured using linearly polarised tagged photons at the Mainz microtron MAMI for Eγ=180–340 MeV. The data have been analysed in separate missing energy (Em) regions corresponding to the ejection of nucleons from (1p)2 and (1p)(1s) shells. The measured Σ values for both Em regions are smaller in magnitude than corresponding 2H data, but the (1p)2 results have a similar Eγ dependence. Calculations of direct two-nucleon emission overestimate the magnitude of Σ at all photon energies.
ATLAS level-1 calorimeter trigger: subsystem tests of a Jet/Energy-sum Processor module
2003
The ATLAS Level-1 Calorimeter Trigger consists of a Preprocessor, a Cluster Processor (CP), and a Jet/Energy-sum Processor (JEP). The CP and JEP receive digitised trigger-tower data from the Preprocessor and produce trigger multiplicities and total and missing energy for the final trigger decision. The trigger will also provide region-of-interest (RoI) information for the Level-2 trigger and intermediate results of the data acquisition (DAQ) system for monitoring and diagnostics by using readout driver modules (ROD). The Jet/Energy-sum Processor identifies and localises jets, and sums total and missing transverse energy information from the trigger data. The Jet/Energy Module (JEM) is the m…
Measurements of the electron-helicity asymmetry in the quasi-elastic A(e→,e′p) process
2022
Abstract We present measurements of the electron helicity asymmetry in quasi-elastic proton knockout from 2H and 12C nuclei by polarized electrons. This asymmetry depends on the fifth structure function, is antisymmetric with respect to the scattering plane, and vanishes in the absence of final-state interactions, and thus it provides a sensitive tool for their study. Our kinematics cover the full range in off-coplanarity angle ϕ p q , with a polar angle θ p q coverage up to about 8°. The missing energy resolution enabled us to determine the asymmetries for knock-out resulting in different states of the residual 11B system. We find that the helicity asymmetry for p-shell knockout from 12C d…
Probing short-range nucleon-nucleon correlations with virtual photons at MAMI
2000
Abstract Nucleon-nucleon correlations were studied in two (e, e′pp) experiments. The first one, on 12C, was performed in close to 4π geometry at Ebeam = 705 MeV, ω = 225 MeV, and q = 412 MeV/c. The electrons were observed in a large-acceptance magnetic spectrometer in coincidence with protons detected in a BGO crystal ball. Missing energy and momentum, relative momentum and angular distributions were derived and compared with a facorised two-nucleon emision model. A G-matrix correlation function is favoured by the data. The second experiment was a high resolution study of the reaction 16O(e, e′pp)14C in super-parallel kinematics. Three magnetic spectrometers were used in coincidence at Ebea…
Searches for Supersymmetry in the photon(s) plus missing energy channels at $\sqrt{s}$ = 161 GeV and 172 GeV
1997
Searches for supersymmetric particles in channels with one or more photons and missing energy have been performed with data collected by the ALEPH detector at LEP. The data consist of 11.1 pb-1 at $\sqrt{s} = 161 GeV$, 1.1 pb-1 at 170 GeV and 9.5 pb-1 at 172 GeV. The e+e- -> nunu+photon cross section is measured. The data are in good agreement with predictions based on the Standard Model, and are used to set upper limits on the cross sections for anomalous photon production. These limits are compared to two different SUSY models and used to set limits on the neutralino mass. A limit of 71 GeV/c^2 at 95% C.L. is set on the mass of the lightest neutralino ($\tau_{\chi_{1}^{0}} \leq $ 3 ns) fo…
Doubly charged Higgs at LHC
1996
We have investigated production of doubly charged Higgs particles $\Delta_{L,R}^{++}$ via WW fusion process in proton-proton collisions at LHC energies in the framework of the left-right symmetric model. The production cross section of the right-triplet Higgs is for representative values of model parameters at femtobarn level. The discovery reach depends on the mass of the right-handed gauge boson W_R. At best $\Delta_R^{++}$ mass up to 2.4 TeV are achievable within one year run. For $\Delta^{++}_L$ the corresponding limit is 1.75 TeV which depends on the value of the left-triplet vev v_L. Comparison with Drell-Yan pair production processes shows that studies of the WW fusion processes exte…
Search for anomalous quarticWWγγcouplings in dielectron and missing energy final states inpp¯collisions ats=1.96 TeV
2013
We present a search for anomalous components of the quartic gauge boson coupling WW gamma gamma in events with an electron, a positron and missing transverse energy. The analyzed data correspond to 9.7 fb(-1) of integrated luminosity collected by the D0 detector in p (p) over bar collisions at root s 1.96 TeV. The presence of anomalous quartic gauge couplings would manifest itself as an excess of boosted WW events. No such excess is found in the data, and we set the most stringent limits to date on the anomalous coupling parameters a(0)(W) and a(C)(W). When a form factor with Lambda(cutoff) = 0.5 TeV is used, the observed upper limits at 95% C. L. are vertical bar a(0)(W)/Lambda(2)vertical …
The Higgs sector of the munuSSM and collider physics
2011
Journal of High Energy Physics 2011.10 (2011): 020 reproduced by permission of Scuola Internazionale Superiore di Studi Avanzati (SISSA)
Searching for Invisibly Decaying Higgs Bosons at LEP II
1996
We study the potential of LEP II to unravel the existence of invisibly decaying Higgs bosons, predicted in a wide class of models. We perform a model independent analysis, focusing our attention to the final state topologies exhibiting $b \bar{b}$ or $\ell^+ \ell^-$ ($\ell=\mu$ or $e$) pairs and missing energy. We carefully evaluate the signals and backgrounds, choosing appropriate cuts to enhance the discovery limits. Our results demonstrate that LEP II is capable of discovering such a Higgs boson for a wide range of masses and couplings.