3,367 research outputs found

### SUSY parameter determination

The impact of the LHC, SLHC and the ILC on the precision of the determination
of supersymmetric parameters is investigated. In particular, in the point SPS1a
the measurements performed at the ILC will improve by an order of magnitude the
precision obtained by the LHC alone. The SLHC with respect to the LHC has the
potential to reduce the errors by a factor two.Comment: Invited talk at 2005 International Linear Collider Physics and
Detector Workshop and Second ILC Accelerator Workshop, Snowmass,
CO(Snowmass05) 3 pages, LaTe

### The Higgs Sector of the Next-to-Minimal Supersymmetric Standard Model

The Higgs boson spectrum of the Next-to-Minimal Supersymmetric Standard Model
is examined. The model includes a singlet Higgs field S in addition to the two
Higgs doublets of the minimal extension. `Natural' values of the parameters of
the model are motivated by their renormalization group running and the vacuum
stability. The qualitative features of the Higgs boson masses are dependent on
how strongly the Peccei-Quinn U(1) symmetry of the model is broken, measured by
the self-coupling of the singlet field in the superpotential. We explore the
Higgs boson masses and their couplings to gauge bosons for various
representative scenarios.Comment: 32 pages with 12 figures; references and parameters updated; a few
minor comments adde

### SFitter: Reconstructing the MSSM Lagrangian from LHC data

Once supersymmetry is found at the LHC, the question arises what are the
fundamental parameters of the Lagrangian. The answer to this question should
thereby not be biased by assumptions on high-scale models. SFitter is a tool
designed for this task. Taking LHC (and possibly ILC) data as input it scans
the TeV-scale MSSM parameter space using its new weighted Markov chain
technique. Using this scan it determines a list of best-fitting parameter
points. Additionally a log-likelihood map is calculated, which can be reduced
to lower-dimensional Frequentist's profile likelihoods or Bayesian probability
maps.Comment: Submitted for the SUSY07 proceedings, 4 pages, LaTeX, 4 eps figure

### Identifying the Higgs Spin and Parity in Decays to Z Pairs

Higgs decays to Z boson pairs may be exploited to determine spin and parity
of the Higgs boson, a method complementary to spin-parity measurements in
Higgs-strahlung. For a Higgs mass above the on-shell ZZ decay threshold, a
model-independent analysis can be performed, but only by making use of
additional angular correlation effects in gluon-gluon fusion at the LHC and
gamma-gamma fusion at linear colliders. In the intermediate mass range, in
which the Higgs boson decays into pairs of real and virtual Z bosons, threshold
effects and angular correlations, parallel to Higgs-strahlung, may be adopted
to determine spin and parity, though high event rates will be required for the
analysis in practice.Comment: 14 pages, 2 postscript figure

### Reconstruction of fundamental SUSY parameters at LHC and at a future linear collider

Presentation par R. LafayeUnveiling the mechanism leading to the breaking of supersymmetry is among the outstanding questions for future colliders. To achieve this goal, models will need to be scrutinized and their parameters assessed. Global fitting tools, like Fittino and SFitter, have been developed and set a robust framework for such analyses. Using the SPS1a snowmass point as an example for the SUSY and Higgs particles that could be observed at the LHC and at a future TeV Linear Collider, we have studied the determination and its precision of MSUGRA parameters from the measurements expected in this point. While the LHC will provide the first measurement of the parameters, the Linear Collider will increase their precision by an order of magnitude. However, when moving to the unconstrained weak-scale MSSM, measurements from the LHC, such as the gluino and squarks masses and couplings, and from the LC, such as charginos and high precision slepton mass measurements, are necessary to reconstruct the Lagrangian with the best available precision. Using a set of hypothetical measurements at LHC and at a future LC, we will show how these colliders probe different sectors of the MSSM Lagrangian and how this complementarity increases our handle on the determination of the weak-scale parameters of the Lagrangian. In fact, the combination of the measurements of the LHC and the LC is essential to probe the complete MSSM weak-scale lagrangian

### HIGGS BOSON PRODUCTION AT THE LHC

Gluon fusion is the main production mechanism for Higgs particles at the LHC.
We present the QCD corrections to the fusion cross sections for the Higgs boson
in the Standard Model, and for the neutral Higgs bosons in the minimal
supersymmetric extension of the Standard Model. The QCD corrections are in
general large and they increase the cross sections significantly. In two steps
preceding the calculation of the production processes, we determine the QCD
radiative corrections to Higgs decays into two photons and gluons.Comment: 82 pages, latex, 26 figures (not included, available upon request

### Gold-plated processes at photon colliders

We review the most important topics and objectives of the physics program of
the gamma-gamma, gamma-electron collider (photon collider) option for an e+e-
linear collider.Comment: 36 pages, Latex, 11 figures(ps,eps), Talk at Intern. Workshop on High
Energy Photon Colliders; June 14-17, 2000, DESY, Hamburg, Germany; to be
published in Nucl. Instr. and Methods

### Higgs signals and hard photons at the Next Linear Collider: the $ZZ$-fusion channel in the Standard Model

In this paper, we extend the analyses carried out in a previous article for
$WW$-fusion to the case of Higgs production via $ZZ$-fusion within the Standard
Model at the Next Linear Collider, in presence of electromagnetic radiation due
real photon emission. Calculations are carried out at tree-level and rates of
the leading order (LO) processes e^+e^-\rightarrow e^+e^- H \ar e^+e^- b\bar b
and e^+e^-\rightarrow e^+e^- H \ar e^+e^- WW \ar e^+e^- \mathrm{jjjj} are
compared to those of the next-to-leading order (NLO) reactions
e^+e^-\rightarrow e^+e^- H (\gamma)\ar e^+e^- b\bar b \gamma and
e^+e^-\rightarrow e^+e^- H (\gamma)\ar e^+e^- WW (\gamma) \ar e^+e^-
\mathrm{jjjj}\gamma, in the case of energetic and isolated photons.Comment: 12 pages, LaTeX, 5 PostScript figures embedded using epsfig and
bitmapped at 100dpi, complete paper including high definition figures
available at ftp://axpa.hep.phy.cam.ac.uk/stefano/cavendish_9611.ps or at
http://www.hep.phy.cam.ac.uk/theory/papers

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