4,423 research outputs found
Effective action of a five-dimensional domain wall
We calculate the four-dimensional low-energy effective action for the
perturbations of a two-scalar domain wall model in five dimensions. Comparison
of the effective action to the Nambu-Goto action reveals the presence of an
additional coupling between the light scalar field and the massless translation
mode (branon excitation), which can be written in terms of the curvature scalar
of the induced metric. We comment on the impact of this interaction to branon
physics.Comment: 24 page
Measuring the SUSY Breaking Scale at the LHC in the Slepton NLSP Scenario of GMSB Models
We report a study on the measurement of the SUSY breaking scale sqrt(F) in
the framework of gauge-mediated supersymmetry breaking (GMSB) models at the
LHC. The work is focused on the GMSB scenario where a stau is the
next-to-lightest SUSY particle (NLSP) and decays into a gravitino with lifetime
c*tau_NLSP in the range 0.5 m to 1 km. We study the identification of
long-lived sleptons using the momentum and time of flight measurements in the
muon chambers of the ATLAS experiment. A realistic evaluation of the
statistical and systematic uncertainties on the measurement of the slepton mass
and lifetime is performed, based on a detailed simulation of the detector
response. Accessible range and precision on sqrt(F) achievable with a counting
method are assessed. Many features of our analysis can be extended to the study
of different theoretical frameworks with similar signatures at the LHC.Comment: 28 pages, 12 figures (18 eps files). Revised version v2(published in
JHEP): Some important corrections and additions to v
Aspects of GMSB Phenomenology at TeV Colliders
The status of two on-going studies concerning important aspects of the
phenomenology of gauge-mediated supersymmetry breaking (GMSB) models at TeV
colliders is reported. The first study deals with the characteristics of the
light Higgs boson spectrum allowed by the (minimal and non-minimal) GMSB
framework. Today's most accurate GMSB model generation and two-loop
Feynman-diagrammatic calculation of m_h have been combined. The Higgs masses
are shown in dependence of various model parameters at the messenger and
electroweak scales. In the minimal model, an upper limit on m_h of about 124
GeV is found for m_t = 175 GeV. The second study is focused on the measurement
of the fundamental SUSY breaking scale sqrt(F) at the LHC in the GMSB scenario
where a stau is the next-to-lightest SUSY particle (NLSP) and decays into a
gravitino with c*tau_NLSP in the range 0.5 m to 1 km. This implies the
measurement of mass and lifetime of long lived sleptons. The identification is
performed by determining the time of flight in the ATLAS muon chambers.
Accessible range and precision on sqrt(F) achievable with a counting method are
assessed.Comment: 22 pages, 9 figures (12 eps files). Report of the GMSB SUSY Working
Group, Workshop "Physics at TeV Colliders", Les Houches, 7-18 June 1999.
Revised version v3: A few typos correcte
Searching for massless dark photons at the lhc via higgs production
Massless dark photons are predicted in hidden-sector models with an unbroken dark U(1) gauge symmetry. A particular class of these models, aiming to solve both the Yukawa-hierarchy and the dark-matter problems of the standard model, manifests natural Higgs nondecoupling properties for the dark photon. As a consequence, we show that the Higgs-boson production at colliders followed by the Higgs decay into a photon and a dark photon provides a very promising dark-photon production mechanism. This decay gives rise to an unconventional Higgs signature characterized by a resonating gamma-plus-missing-momentum system with a monochromatic photon. We discuss the sensitivity of the LHC to the corresponding signal for a Higgs boson produced in both gluon-fusion and vector-boson-fusion channels. © Copyright owned by the author(s).Peer reviewe
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