This paper presents the final interpretation of the results from DELPHI on the searches for Higgs bosons in the Minimal Supersymmetric extension of the Standard Model (MSSM). A few representative scenarios are considered, that include CP conservation and explicit CP violation in the Higgs sector. The experimental results encompass the searches for neutral Higgs bosons at LEP1 and LEP2 in final states as expected in the MSSM, as well as LEP2 searches for charged Higgs bosons and for neutral Higgs bosons decaying into hadrons independent of the quark flavour. The data reveal no significant excess with respect to background expectations. The results are translated into excluded regions of the parameter space in the various scenarios. In the CP-conserving case, these lead to limits on the masses of the lightest scalar and pseudoscalar Higgs bosons, h and A, and on tan(beta). The dependence of these limits on the top quark mass is discussed. Allowing for CP violation reduces the experimental sensitivity to Higgs bosons. It is shown that this effect depends strongly on the values of the parameters responsible for CP violation in the Higgs sector.
These final results from DELPHI searches for the Standard Model SM Higgs boson, together with benchmark scans of the Minimal Supersymmetric Standard Model MSSM neutral Higgs bosons, used data taken at centre-of-mass energies between 200 and 209GeV with a total integrated luminosity of 224inv. pb.The data from 192 to 202GeV are reanalysed with improved b-tagging for MSSM final states decaying to four b-quarks. The 95% confidence level lower mass bound on the Standard Model Higgs boson is 114.1GeV. Mass limits are also given on the lightest scalar and pseudo-scalar Higgs bosons of the MSSM.
These final results from DELPHI searches for the Standard Model (SM) Higgs boson, together with benchmark scans of the Minimal Supersymmetric Standard Model (MSSM) neutral Higgs bosons, used data taken at centre-of-mass energies between 200 and 209 GeV with a total integrated luminosity of 224 pb^-1. The data from 192 to 202 GeV are reanalysed with improved b-tagging for MSSM final states decaying to four b-quarks. The 95% confidence level lower mass bound on the Standard Model Higgs boson is 114.1 GeV/c2. Limits are also given on the lightest scalar and pseudo-scalar Higgs bosons of the MSSM.
The data taken by DELPHI at centre-of-mass energies between 189 and 209 GeV are used to place limits on the CP-conserving trilinear gauge boson couplings Delta_g1z, lambda_gamma and Delta_kappag associated to W+W- and single W production at LEP2. Using data from the jjlv, jjjj, jjX and lX final states, where j, l and X represent a jet, a lepton and missing four-momentum, respectively, the following limits are set on the couplings when one parameter is allowed to vary and the others are set to their Standard Model values of zero: Delta_g1z = -0.025^{+0.033}_{-0.030}, lambda_gamma = 0.002^{+0.03…
This report summarizes the final results from the OPAL collaboration on searches for neutral Higgs bosons predicted by the Minimal Supersymmetric Standard Model (MSSM). CP-conserving and for the first time at LEP CP-violating scenarios are studied. New scenarios are also included, which aim to set the stage for Higgs searches at future colliders. The results are based on the data collected with the OPAL detector at e+e- centre-of-mass energies up to 209 GeV. The data are consistent with the prediction of the Standard Model with no Higgs boson produced. Model-independent limits are derived for …
Searches for HZ production with the Higgs boson decaying into an invisible final state were performed using the data collected by the DELPHI experiment at centre-of-mass energies between 188 GeV and 209 GeV. Both hadronic and leptonic final states of the Z boson were analysed. In addition to the search for a heavy Higgs boson, a dedicated search for a light Higgs boson down to 40 GeV/c^2 was performed. No signal was found. Assuming the Standard Model HZ production cross-section, the mass limit for invisibly decaying Higgs bosons is 112.1 GeV/c^2 at 95% confidence level. An interpretation in th…
The LEP collaborations ALEPH, DELPHI, L3 and OPAL have searched for the neutral Higgs bosons which are predicted within the framework of the Minimal Supersymmetric Standard Model (MSSM). The data of the four collaborations are statistically combined and show no signicant excess of events which would indicate the production of Higgs bosons. The search results are thus used to set upper bounds on the cross sections of various Higgs-like event topologies and limits on MSSM benchmark models, including CP-conserving and CP-violating scenarios. Here, the limits on the model parameters of the CP-viol…
The CMS and ATLAS collaborations have performed detailed studies of the discovery potential for the Higgs boson in MSSM. Different benchmarks scenarios have been studied both for the CP-conserving case and for the CP-violating one. Results are presented of the discovery potential in the parameter space of MSSM.
The four LEP collaborations, ALEPH, DELPHI, L3 and OPAL, have searched for the neutral Higgs bosons which are predicted by the Minimal Supersymmetric Standard Model (MSSM). The data of the four collaborations are statistically combined and examined for their consistency with the background hypothesis and with a possible Higgs boson signal. The combined LEP data show no significant excess of events which would indicate the production of Higgs bosons. The search results are used to set upper bounds on the cross-sections of various Higgs-like event topologies. The results are interpreted within t…
This paper discusses recent publications of the LEP collaborations DELPHI, L3 and OPAL on searches for Higgs bosons motivated by MSSM scenarios as well as their interpretation in the MSSM. With the final publication of the LEP collaborations available or awaited, more and more interpretations in different MSSM models, including both CP conserving and CP violating, become available. Also specialized analyses close open areas in the parameter space. In the same time, better theoretical calculations with an increased maximal mass of the Higgs boson were presented. Both the new scenarios as well a…
DELPHI data collected at centre-of-mass energies up to 208 GeV have been analysed to search for charginos, neutralinos and sfermions in the framework of the Minimal Supersymmetric Standard Model (MSSM) with R-parity conservation. No evidence for a signal was found in any of the channels. The results of each search were used to derive limits on production cross-sections and particle masses. In addition, the combined result of all searches excludes regions in the parameter space of the constrained MSSM, leading to limits on the mass of the Lightest Supersymmetric Particle and other supersymmetri…
Searches for R-parity conserving supersymmetric particles have been performed in e+e- data collected by LEP detectors, at centre-of-mass energies up to 209GeV, corresponding to an integrated luminosity of 3.1fb-1. The results and their interpretation in the context of MSSM frameworks are briefly reviewed.
Neutral Higgs bosons of the Standard Model (SM) and the Minimal Supersymmetric Standard Model (MSSM) were searched for in the data collected in 1999 by the DELPHI experiment at centre-of-mass energies between 191.6 and 201.7 GeV with a total integrated luminosity of 228 pb^{-1}. These analyses, in combination with our results at lower energies, set 95% confidence level lower mass bounds on the Standard Model Higgs boson (107.3 GeV/c^2) and on the lightest neutral scalar (85.9 GeV/c^2) and neutral pseudoscalar (86.5 GeV/c^2) Higgs bosons in representative scans of the MSSM parameter space. An e…
It is important to study extended models containing more than one physical Higgs boson in the spectrum. In particular, Two Higgs Doublet Models (2HDMs) are attractive extensions of the SM, predicting new phenomena with the fewest new parameters. The Higgs sector in the Minimal Supersymmetric extension of the SM (MSSM) is a 2HDM itself. The neutral Higgs searches performed at LEP are showing no evidence of the presence of a signal and have therefore been interpreted in the context of 2HDMs. Depending on the model considered exclusion of large regions of the parameter space can be obtained, but …
The four LEP experiments, ALEPH, DELPHI, L3 and OPAL, have searched for Higgs bosons predicted by a large number of extensions of the Standard Model. Flavor independent searches are presented for the h$^{0}$Z$^{0}$ process in which the h$^{0}$ decays hadronically. Search results are also presented for fermiophobic Higgs bosons, invisibly decaying Higgs bosons, charged Higgs bosons and the neutral Higgs bosons in the MSSM.
In this article the potential of the ATLAS experiment to discover MSSM Higgs bosons is discussed. Various Monte-Carlo studies for SM Higgs boson production and dedicated MSSM Higgs boson analyses are taken into account to investigate the discovery potential in four different CP-conserving MSSM benchmark scenarios, the Mh-max scenario, the no mixing scenario, the gluophobic scenario and the small alpha scenario. The most recent theoretical calculations are used for the prediction of Higgs masses and couplings. The results are shown for integrated luminosities of 30 and 300 inverse fb. With 300 …
Searches for neutral Higgs bosons in the Standard Model and the MSSM have been performed using data collected by the DELPHI experiment at a centre-of-mass energy of 188.7 GeV, corresponding to an integrated luminosity of 158 pb^{-1}. These analyses are used, in combination with our results from lower energies, to set new 95% confidence level lower mass bounds on the Standard Model Higgs boson (94.6 GeV/c^2) and on the lightest neutral scalar (82.6 GeV/c^2) and neutral pseudoscalar (84.1 GeV/c^2) Higgs bosons in a representative scan of the MSSM parameters. The results are also interpreted in t…
Searches for spontaneous R-parity violating signals at sqrt(s) = 183 GeV and sqrt(s) = 189 GeV have been performed using the 1997 and 1998 DELPHI data, under the assumption of R-parity breaking in the third lepton family. The expected topology for the decay of a pair of charginos into two acoplanar taus plus missing energy was investigated and no evidence for a signal was found. The results were used to derive a limit on the chargino mass and to constrain the allowed domains of the MSSM parameter space.
The ATLAS and CMS collaborations have observed independently at the Large Hadron Collider (LHC) a new Higgs-like particle with a mass $M_h \sim$ 125 GeV and properties similar to that predicted by the Standard Model (SM). Although the measurements indicate that this Higgs-like boson is compatible with the SM hypothesis, however due to large uncertainties in some of the Higgs detection channels, one still has the possibility of testing this object as being a candidate for some Beyond the SM (BSM) physics scenarios, for example, the Minimal Supersymmetric Standard Model (MSSM), in the CP-conserv…
A summary of the constraints from the ATLAS experiment on $R$-parity conserving supersymmetry is presented. Results from 22 separate ATLAS searches are considered, each based on analysis of up to 20.3 fb$^{-1}$ of proton-proton collision data at the centre-of-mass energy of $\sqrt{s}$ = 7 and 8 TeV at the Large Hadron Collider. The results are interpreted in the context of the 19-parameter phenomenological minimal supersymmetric standard model, in which the lightest supersymmetric particle is a neutralino, taking into account constraints from previous precision electroweak and flavour measurem…
We present SUSY_FLAVOR -- a Fortran 77 program that calculates important leptonic and semi-leptonic low-energy observables in the general R-parity conserving MSSM. For a set of input MSSM parameters, the code gives predictions for the K0-bar K0, D-bar D, B_d-bar B_d and B_s-bar B_s mixing parameters; B to X_s gamma, B_{s,d} to l+ l-, K0_L to pi nu-bar nu and K+ to pi+ nu-bar nu decay branching ratios; and the electric dipole moments of the leptons and the neutron. All these quantities are calculated at one-loop level (with some higher-order QCD corrections included) in the exact sfermion mass …
We investigate the NLO QCD and the CP-violation effects in $t\bar{t}Z^0$ production at the Large Hadron Collider(LHC) in the minimal supersymmetric standard model(MSSM). Our calculation shows that the total NLO QCD correction in the framework of the CP-conserving MSSM significantly improves the scale uncertainty at the leading order, and the contribution from the pure supersymmetric QCD (pSQCD) correction can exceed $-8\%$ with the restrictions of $90~GeV < p_T^t < 120~GeV$ and $120~GeV < p_T^Z < 150~GeV$, where $p_T^t$ and $p_T^Z$ are the transverse momenta of the top-quark and $Z^0$ gauge bo…
Experimental collaborations for the large hadron collider conducted many and various searches for supersymmetry. In the absence of signals, lower limits were put on sparticle masses but usually within frameworks with (over-) simplifications relative to the entire indications by supersymmetry models. For complementing current interpretations of experimental bounds, we introduce a 30-parameters version of the R-parity conserving minimal supersymmetric standard model (MSSM-30). Using a sample of the MSSM-30 which are in harmony with cold dark matter, flavour and precision electroweak constraints,…
Searches have been conducted for a broad range of new phenomena by the four experiments ALEPH, DELPHI, L3, and OPAL, at LEP2. Each experiment contributes approximately 150 pb-1 of e+e- annihilation data with a mean sqrt(s) of 205.9 GeV in 2000 to these searches (data prepared for the September 5 LEPC meeting). The statistical procedure for setting limits and evaluating the significance of excesses observed in the data is reviewed. Search results are presented for the Standard Model Higgs boson, the neutral Higgs bosons in the MSSM, charged Higgs bosons, invisibly decaying Higgs bosons produced…
A search for squarks in R-parity violating supersymmetry is performed in e^+p collisions at HERA at a centre of mass energy of 300 GeV, using H1 data corresponding to an integrated luminosity of 37 pb^(-1). The direct production of single squarks of any generation in positron-quark fusion via a Yukawa coupling lambda' is considered, taking into account R-parity violating and conserving decays of the squarks. No significant deviation from the Standard Model expectation is found. The results are interpreted in terms of constraints within the Minimal Supersymmetric Standard Model (MSSM), the cons…
Accurate supersymmetric spectra are required to confront data from direct and indirect searches of supersymmetry. \SUSEFLAV is a numerical tool which is capable of computing supersymmetric spectra accurately for various supersymmetric breaking scenarios applicable even in the presence of flavor violation. The program solves MSSM RGEs with complete $3\times3$ flavor mixing at 2-loop level and one loop finite threshold corrections to all MSSM parameters by incorporating radiative electroweak symmetry breaking conditions. The program also incorporates the Type-I seesaw mechanism with three massiv…
We consider the natural supersymmetry scenario in the framework of the R-parity conserving minimal supersymmetric standard model (called natural MSSM) and examine the observability of stop pair production at the LHC. We first scan the parameters of this scenario under various experimental constraints, including the SM-like Higgs boson mass, the indirect limits from precision electroweak data and B-decays. Then in the allowed parameter space we study the stop pair production at the LHC followed by the stop decay into a top quark plus a lightest neutralino or into a bottom quark plus a chargino.…
We have analysed the data collected by OPAL at centre-of-mass energies between 189 and 209 GeV searching for Higgs boson candidates from the process e+e- -> h0Z0 followed by the decay of h0 -> A0A0 where A0 is the CP-odd Higgs boson. The search is done in the region where the A0 mass, mA, is below the production threshold for bbbar, and the CP-even Higgs boson mass mh is within the range 45-86 GeV/c^2. In this kinematic range, the decay of h0 -> A0A0 may be dominant and previous Higgs boson searches have very small sensitivities. This search can be interpreted within any model that predicts th…
We investigate the phenomenology of the MSSM extended by a single R-parity violating coupling at the unification scale. For all R-parity violating couplings, we discuss the evolution of the particle spectra through the renormalization group equations and the nature of the lightest supersymmetric particle (LSP) within the CMSSM, as an example of a specific complete supersymmetric model. We use the nature of the LSP to classify the possible signatures. For each possible scenario we present in detail the current LHC bounds on the supersymmetric particle masses, typically obtained using simplified…
