493 research outputs found
MW and sin^2\theta_eff in Split SUSY: present and future expectations
We analyse the precision electroweak observables MW and sin^2\theta_eff and
their correlations in the recently proposed Split SUSY model. We compare the
results with the Standard Model and Minimal Supersymmetric Standard Model
predictions, and with present and future experimental accuracies. Present
experimental accuracies in (MW, sin^2\theta_eff) do not allow constraints to be
placed on the Split SUSY parameter space. We find that the shifts in (MW,
sin^2\theta_eff) induced by Split SUSY can be larger than the anticipated
accuracy of the GigaZ option of the International Linear Collider, and that the
most sensitive observable is sin^2\theta_eff. These large shifts are possible
also for large chargino masses in scenarios with small tan(\beta) =~ 1.Comment: LaTeX, 13 pages, 4 figures. Comments adde
Electroweak Physics at the ILC
Some aspects of electroweak physics at the International Linear Collider
(ILC) are reviewed. The importance of precision measurements in the Higgs
sector and in top-quark physics is emphasized, and the physics potential of the
GigaZ option of the ILC is discussed. It is shown in particular that even in a
scenario where the states of new physics are so heavy that they would be
outside of the reach of the LHC and the first phase of the ILC, the GigaZ
precision on the effective weak mixing angle may nevertheless allow the
detection of quantum effects of new physics.Comment: 5 pages, contribution to the proceedings of EPS0
Precision Calculations for Future Colliders
I discuss the motivations for, and the status of, precision calculations for
the Large Hadron Collider (LHC) and the planned International Linear Collider
(ILC).Comment: latex, uses ws-ijmpe.cls, 19 pages, 9 figures, 1 table, based on a
talk given at the symposium "50 Years of High Energy Physics at UB", to
appear in International Journal of Modern Physics
A SM-like Higgs near 125 GeV in low energy SUSY: a comparative study for MSSM and NMSSM
Motivated by the recent LHC hints of a Higgs boson around 125 GeV, we assume
a SM-like Higgs with the mass 123-127 GeV and study its implication in low
energy SUSY by comparing the MSSM and NMSSM. We consider various experimental
constraints at 2-sigma level (including the muon g-2 and the dark matter relic
density) and perform a comprehensive scan over the parameter space of each
model. Then in the parameter space which is allowed by current experimental
constraints and also predicts a SM-like Higgs in 123-127 GeV, we examine the
properties of the sensitive parameters (like the top squark mass and the
trilinear coupling A_t) and calculate the rates of the di-photon signal and the
VV^* (V=W,Z) signals at the LHC. Our typical findings are: (i) In the MSSM the
top squark and A_t must be large and thus incur some fine-tuning, which can be
much ameliorated in the NMSSM; (ii) In the MSSM a light stau is needed to
enhance the di-photon rate of the SM-like Higgs to exceed its SM prediction,
while in the NMSSM the di-photon rate can be readily enhanced in several ways;
(iii) In the MSSM the signal rates of pp -> h -> VV^* at the LHC are never
enhanced compared with their SM predictions, while in the NMSSM they may get
enhanced significantly; (iv) A large part of the parameter space so far
survived will be soon covered by the expected XENON100(2012) sensitivity
(especially for the NMSSM).Comment: Version in JHEP (refs added
Optical spectra obtained from amorphous films of rubrene: Evidence for predominance of twisted isomer
In order to investigate the optical properties of rubrene we study the
vibronic progression of the first absorption band (lowest \pi -> \pi^*
transition). We analyze the dielectric function of rubrene in solution and thin
films using the displaced harmonic oscillator model and derive all relevant
parameters of the vibronic progression. The findings are supplemented by
density functional calculations using B3LYP hybrid functionals. Our theoretical
results for the molecule in two different conformations, i.e. with a twisted or
planar tetracene backbone, are in very good agreement with the experimental
data obtained for rubrene in solution and thin films. Moreover, a simulation
based on the monomer spectrum and the calculated transition energies of the two
conformations indicates that the thin film spectrum of rubrene is dominated by
the twisted isomer.Comment: 7 pages, 6 figure
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