648 research outputs found
Comparative analysis of the four-fermion contact interactions at e^+e^- and e^-e^- colliders
We study electron-electron contact-interaction searches in the process
e^+e^-\to e^+e^- at a future e^+e^- Linear Collider with both beams
longitudinally polarized. We evaluate the model-independent constraints on the
coupling constants, emphasizing the role of beam polarization, and make a
comparison with the case of e^+e^-\to\mu^+\mu^-.Comment: 5 pages with 3 figures. Talk given at the VII-th International School
- Seminar ``The Actual Problems of Microworld Physics'', Gomel, 28 July - 8
August, 200
Self-doping instability of the Wigner-Mott insulator
We present a theory describing the mechanism for the two-dimensional (2D)
metal-insulator transition (MIT) in absence of disorder. A two-band Hubbard
model is introduced, describing vacancy-interstitial pair excitations within
the Wigner crystal. Kinetic energy gained by delocalizing such excitations is
found to lead to an instability of the insulator to self-doping above a
critical carrier concentration , mapping the problem to a density-driven
Mott MIT. This mechanism provides a natural microscopic picture of several
puzzling experimental features, including the large effective mass enhancement,
the large resistivity drop, and the large positive magneto-resistance on the
metallic side of the transition. We also present a global phase diagram for the
clean 2D electron gas as a function of and parallel magnetic field
, which agrees well with experimental findings in ultra
clean samples.Comment: 5 pages, 2 figure
Signals of Warped Extra Dimensions at the LHC
We discuss the signatures of the spin-2 graviton excitations predicted by the
Randall-Sundrum model with one warped extra dimension, in dilepton and diphoton
production at LHC. By using a specific angular analysis, we assess the ranges
in mass and coupling constant where such gravitons can be discriminated against
competitor spin-1 and spin-0 objects, that potentially could manifest
themselves in these processes with the same mass and rate of events. Depending
on the value of the coupling constant to quarks and leptons, the numerical
results indicate graviton identification mass ranges up to 1.1-2.4 TeV and
1.6-3.2 TeV for LHC nominal energy of 14 TeV and time-integrated luminosity of
10 and 100~, respectively.Comment: 8 pages, Talk given at QCD@Work - International Workshop on QCD -
Theory and Experiment, 20 - 23 June, 2010, Martina Franca Ital
Discriminating Z’ from anomalous gauge coupling signatures in e+e- W+W- at International Linear Collider
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