4,219 research outputs found
ATLAS prospects for beyond the Standard Model searches
We discuss how ATLAS has been preparing for the analysis of the first fb-1 of good data at 14 TeV in view of discovering new physics beyond the Standard Model. We show some ideas developed for understanding the backgrounds and we present as realistic as possible estimates of the reach of the experiment
Indirect limits on SUSY Rp violating couplings lambda and lambda'
We review and update as many as possible indirect limits on SUSY Rp violating couplings lambda and lambda'. We consider about 25 experimental measurements and compare them to their expectation value in the standard model. We find more stringent limits on almost all of the parameter
Report of the GDR working group on the R-parity violation
This report summarizes the work of the "R-parity violation group" of the
French Research Network (GDR) in Supersymmetry, concerning the physics of
supersymmetric models without conservation of R-parity at HERA, LEP, Tevatron
and LHC and limits on R-parity violating couplings from various processes. The
report includes a discussion of the recent searches at the HERA experiment,
prospects for new experiments, a review of the existing limits, and also
theoretically motivated alternatives to R-parity and a brief discussion on the
implications of R-parity violation on the neutrino masses.Comment: 60 pages, LaTeX, 22 figures, 2 table
Physics Beyond the Standard Model
I briefly summarize the prospects for extending our understanding of physics
beyond the standard model within the next five years.Comment: 9 pages, 2 figures, LaTeX. Presented at the 1999 UK Phenomenology
Workshop, Durham, September 1999. To be published in Journal of Physics
Recent developments in Little Higgs Searches at LHC
Little Higgs searches were started in 2003. Early results were obtained on the heavy top T and heavy Higgs phi++ and on the heavy Z and heavy W decays to a Higgs, with a Higgs mass of 120 GeV. Here the heavy Z (Z_H) and heavy W (W_H) decays to a Higgs, with a Higgs mass of 200 GeV, and the hadronic decays of Z_H and W_H, are presented. The reach of the former is about 2 TeV, provided that cot(theta) is not close to 1. In the latter case, only the W_H->tb decay is shown to be detectable, as opposed to Z_H->bb and Z_H->tt decays
Probing RS scenarios of flavour at LHC via leptonic channels
We study a purely leptonic signature of the Randall-Sundrum scenario with
Standard Model fields in the bulk at LHC: the contribution from the exchange of
Kaluza-Klein (KK) excitations of gauge bosons to the clear Drell-Yan reaction.
We show that this contribution is detectable (even with the low luminosities of
the LHC initial regime) for KK masses around the TeV scale and for sufficiently
large lepton couplings to KK gauge bosons. Such large couplings can be
compatible with ElectroWeak precision data on the Zff coupling in the framework
of the custodial O(3) symmetry recently proposed, for specific configurations
of lepton localizations (along the extra dimension). These configurations can
simultaneously reproduce the correct lepton masses, while generating acceptably
small Flavour Changing Neutral Current (FCNC) effects. This LHC
phenomenological analysis is realistic in the sense that it is based on fermion
localizations which reproduce all the quark/lepton masses plus mixing angles
and respect FCNC constraints in both the hadron and lepton sectors.Comment: 15 pages, 6 Figures, Latex fil
Lightest-neutralino decays in R_p-violating models with dominant lambda^{prime} and lambda couplings
Decays of the lightest neutralino are studied in R_p-violating models with
operators lambda^{prime} L Q D^c and lambda L L E^c involving third-generation
matter fields and with dominant lambda^{prime} and lambda couplings.
Generalizations to decays of the lightest neutralino induced by subdominant
lambda^{prime} and lambda couplings are straightforward. Decays with the
top-quark among the particles produced are considered, in addition to those
with an almost massless final state. Phenomenological analyses for examples of
both classes of decays are presented. No specific assumption on the composition
of the lightest neutralino is made, and the formulae listed here can be easily
generalized to study decays of heavier neutralinos. It has been recently
pointed out that, for a sizable coupling lambda^{prime}_{333}, tau-sleptons may
be copiously produced at the LHC as single supersymmetric particles, in
association with top- and bottom-quark pairs. This analysis of neutralino
decays is, therefore, a first step towards the reconstruction of the complete
final state produced in this case.Comment: 40 pages, 11 figures, version to appear in JHE
KK Parity in Warped Extra Dimension
We construct models with a Kaluza-Klein (KK) parity in a five- dimensional
warped geometry, in an attempt to address the little hierarchy problem present
in setups with bulk Standard Model fields. The lightest KK particle (LKP) is
stable and can play the role of dark matter. We consider the possibilities of
gluing two identical slices of 5D AdS in either the UV (IR-UV-IR model) or the
IR region (UV-IR-UV model) and discuss the model-building issues as well as
phenomenological properties in both cases. In particular, we find that the
UV-IR-UV model is not gravitationally stable and that additional mechanisms
might be required in the IR-UV-IR model in order to address flavor issues.
Collider signals of the warped KK parity are different from either the
conventional warped extra dimension without KK parity, in which the new
particles are not necessarily pair-produced, or the KK parity in flat universal
extra dimensions, where each KK level is nearly degenerate in mass. Dark matter
and collider properties of a TeV mass KK Z gauge boson as the LKP are
discussed.Comment: 35 pages, 11 figure
Position resolution and particle identification with the ATLAS EM calorimeter
In the years between 2000 and 2002 several pre-series and series modules of
the ATLAS EM barrel and end-cap calorimeter were exposed to electron, photon
and pion beams. The performance of the calorimeter with respect to its finely
segmented first sampling has been studied. The polar angle resolution has been
found to be in the range 50-60 mrad/sqrt(E (GeV)). The neutral pion rejection
has been measured to be about 3.5 for 90% photon selection efficiency at pT=50
GeV/c. Electron-pion separation studies have indicated that a pion fake rate of
(0.07-0.5)% can be achieved while maintaining 90% electron identification
efficiency for energies up to 40 GeV.Comment: 32 pages, 22 figures, to be published in NIM
Tevatron-for-LHC Report: Preparations for Discoveries
This is the "TeV4LHC" report of the "Physics Landscapes" Working Group,
focused on facilitating the start-up of physics explorations at the LHC by
using the experience gained at the Tevatron. We present experimental and
theoretical results that can be employed to probe various scenarios for physics
beyond the Standard Model.Comment: 222 pp., additional contribution added, typos/layout correcte
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