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Register a new userCP-odd correlations using jet momenta from tt_bar events at the Tevatron
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We discuss T-odd correlations between jet and lepton momenta in tt_bar events at the Tevatron that can be used to search for CP violation. We identify correlations suitable for the lepton plus jets and purely hadronic top-quark pair decay channels. As an example of CP violation we consider the top-quark anomalous couplings, including its chromo-electric dipole moment, and we estimate the limits that can be placed at the Tevatron.
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The angular distribution in photon-jet production in pbar{p} -> gamma jet X is studied within a generalized factorization scheme taking into account the transverse momentum of the partons in the initial hadrons. Within this scheme an anomalously large cos(2phi) asymmetry observed in the Drell-Yan process could be attributed to the T-odd, spin and transverse momentum dependent parton distribution function h_1^{perp q}(x, p_{perp}^2). The same function is expected to produce a cos(2phi) asymmetry in the photon-jet production cross section. This particular azimuthal asymmetry is estimated to be smaller than the Drell-Yan asymmetry but still of considerable size for Tevatron kinematics, offering a new possibility to study T-odd effects at the Tevatron.
We revisit the effect of CP violating anomalous top-quark couplings in $tbar{t}$ production and decay. We consider $tbar{t}$ production through gluon fusion (and light $q{bar q}$ annihilation) followed by top-quark decay into $bW$ or $bell u$. We find explicit analytic expressions for all the triple products generated by the anomalous couplings that fully incorporate all spin correlations. Our results serve as a starting point for numerical simulations for the LHC.
In this paper, we discuss the observation of exclusive events using the dijet mass fraction as measured by the CDF collaboration at the Tevatron. We compare the data to pomeron exchange inspired models as well as Soft color interaction ones. We also provide the prediction on dijet mass fraction at the LHC using both exclusive and inclusive diffractive events.
The number of photon+jet and Z+jet events suitable for a determination of gluon distribution function in a proton at Tevatron Run II and during the low luminosity runs at future LHC experiments are estimated for various intervals of x and Q^2. These numbers allow to extract gluon distribution in new kinematic regions of 2 * 10^{-3} < x < 1.0 with 1.6*10^3 < Q^2 < 2*10^4 ~(GeV/c)^2 at Tevatron and of 2* 10^{-4} < x < 1.0$ with 1.6*10^3 < Q^2 < 2*10^5 ~(GeV/c)^2 at LHC. The contributions of background events in different Q^2 intervals are also given.
Spin correlations of top quarks produced in hadron collisions have not been observed experimentally with large significance. In this Letter, we propose a new variable that may enable demonstration of the existence of spin correlations with 3-4 sigma significance using just a few hundred dilepton events both at the Tevatron and the LHC. Such number of dilepton events has been observed at the Tevatron. At the LHC, it will become available once integrated luminosity of a few hundred inverse picobarns is collected.
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