12,548 research outputs found
Chain of Hardy-type local reality constraints for qubits
Non-locality without inequality is an elegant argument introduced by L. Hardy
for two qubit systems, and later generalised to qubits, to establish
contradiction of quantum theory with local realism. Interestingly, for
this argument is actually a corollary of Bell-type inequalities, viz. the
CH-Hardy inequality involving Bell correlations, but for greater than 2 it
involves -particle probabilities more general than Bell-correlations. In
this paper, we first derive a chain of completely new local realistic
inequalities involving joint probabilities for qubits, and then, associated
to each such inequality, we provide a new Hardy-type local reality constraint
without inequalities. Quantum mechanical maximal violations of the chain of
inequalities and of the associated constraints are also studied by deriving
appropriate Cirel'son type theorems. These results involving joint
probabilities more general than Bell correlations are expected to provide a new
systematic tool to investigate entanglement.Comment: 10 pages, Late
Search for Excited Quarks in at the LHC
If quarks are composite particles, then excited states are expected to play a
r\^ole in the Large Hadron Collider phenomena. Concentrating on virtual
effects, and using a large part of the CMS detection criteria, we present here
a realistic examination of their effect in diphoton production at the LHC. For
various luminosities, we present the 99 % confidence limit (CL) achievable in
parameter space where is the compositeness scale and
M_{q^*} the mass of the state. For a q^* of mass 0.5 TeV, can be excluded at 99% CL with 30 (200) integrated
luminosity.Comment: 11 pages, 11 figure
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