Top Physics at ATLAS Suruliz, K.
Nuclear physics. Section B, Proceedings supplement,
2011, 2011-1-00, Letnik:
210
Journal Article
We describe the prospects for top physics with early data from the ATLAS experiment, focusing on the measurement of the top pair production cross-section in the single lepton and dilepton channels.
The branching ratio for {eta}{r arrow}{pi}{sup +}{pi}{sup {minus}}{pi}{sup 0}{gamma} is calculated using an effective low-energy Lagrangian. The bremsstrahlung part of the amplitude as well as the ...direct emission term, which is significant, are taken into account. The predicted value for the {eta}{r arrow}{pi}{sup +}{pi}{sup {minus}}{pi}{sup 0}{gamma} decay width is below present experimental limit. A comment on the possible {eta}{prime}{r arrow}{pi}{sup +}{pi}{sup {minus}}{pi}{sup 0}{gamma} decay is made.
JHEP 0705:100,2007 Anomalous U(1)'s are ubiquitous in 4D chiral string models. Their presence
crucially affects the process of moduli stabilisation and cannot be neglected
in realistic set-ups. Their ...net effect in the 4D effective action is to induce
a matter field dependence in the non-perturbative superpotential and a
Fayet-Iliopoulos D-term. We study flux compactifications of IIB string theory
in the presence of magnetised D7 branes. These give rise to anomalous U(1)'s
that modify the standard moduli stabilisation procedure. We consider simple
orientifold models to determine the matter field spectrum and the form of the
effective field theory. We apply our results to one-modulus KKLT and
multi-moduli large volume scenarios, in particular to the Calabi-Yau
P^4_{1,1,1,6,9}. After stabilising the matter fields, the effective action
for the Kahler moduli can acquire an extra positive term that can be used for
de Sitter lifting with non-vanishing F- and D-terms. This provides an explicit
realization of the D-term lifting proposal of hep-th/0309187.
JHEP0804:053,2008 We address the size of supersymmetry-breaking effects within
higher-dimensional settings where the observable sector resides deep within a
strongly warped region, with supersymmetry ...breaking not necessarily localized
in that region. Our particular interest is in how the supersymmetry-breaking
scale seen by the observable sector depends on this warping. We obtain this
dependence in two ways: by computing within the microscopic (string) theory
supersymmetry-breaking masses in supermultiplets; and by investigating how
warping gets encoded into masses within the low-energy 4D effective theory. We
find that the lightest gravitino mode can have mass much less than the
straightforward estimate from the mass shift of the unwarped zero mode. This
lightest Kaluza-Klein excitation plays the role of the supersymmetric partner
of the graviton and has a warped mass m_{3/2} proportional to e^A, with e^A the
warp factor, and controls the size of the soft SUSY breaking terms. We
formulate the conditions required for the existence of a description in terms
of a 4D SUGRA formulation, or in terms of 4D SUGRA together with soft-breaking
terms, and describe in particular situations where neither exist for some
non-supersymmetric compactifications. We suggest that some effects of warping
are captured by a linear $A$ dependence in the Kahler potential. We outline
some implications of our results for the KKLT scenario of moduli stabilization
with broken SUSY.
We study the supersymmetric particle spectra and LHC collider observables for the large-volume string models with a fundamental scale of 10^{11} GeV that arise in moduli-fixed string ...compactifications with branes and fluxes. The presence of magnetic fluxes on the brane world volume, required for chirality, perturb the soft terms away from those previously computed in the dilute-flux limit. We use the difference in high-scale gauge couplings to estimate the magnitude of this perturbation and study the potential effects of the magnetic fluxes by generating many random spectra with the soft terms perturbed around the dilute flux limit. Even with a 40% variation in the high-scale soft terms the low-energy spectra take a clear and predictive form. The resulting spectra are broadly similar to those arising on the SPS1a slope, but more degenerate. In their minimal version the models predict the ratios of gaugino masses to be M_1 : M_2 : M_3=(1.5 - 2) : 2 : 6, different to both mSUGRA and mirage mediation. Among the scalars, the squarks tend to be lighter and the sleptons heavier than for comparable mSUGRA models. We generate 10 fb^{-1} of sample LHC data for the random spectra in order to study the range of collider phenomenology that can occur. We perform a detailed mass reconstruction on one example large-volume string model spectrum. 100 fb^{-1} of integrated luminosity is sufficient to discriminate the model from mSUGRA and aspects of the sparticle spectrum can be accurately reconstructed.
Anomalous U(1)'s are ubiquitous in 4D chiral string models. Their presence crucially affects the process of moduli stabilisation and cannot be neglected in realistic set-ups. Their net effect in the ...4D effective action is to induce a matter field dependence in the non-perturbative superpotential and a Fayet-Iliopoulos D-term. We study flux compactifications of IIB string theory in the presence of magnetised D7 branes. These give rise to anomalous U(1)'s that modify the standard moduli stabilisation procedure. We consider simple orientifold models to determine the matter field spectrum and the form of the effective field theory. We apply our results to one-modulus KKLT and multi-moduli large volume scenarios, in particular to the Calabi-Yau P^4_{1,1,1,6,9}. After stabilising the matter fields, the effective action for the Kahler moduli can acquire an extra positive term that can be used for de Sitter lifting with non-vanishing F- and D-terms. This provides an explicit realization of the D-term lifting proposal of hep-th/0309187.
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