39 research outputs found
Using Tau Polarization for Charged Higgs Boson and SUSY Searches at LHC
The polarization can be easily measured at LHC in the 1-prong hadronic
decay channel by measuring what fraction of the -jet momentum is
carried by the charged track. A simple cut requiring this fraction to be >0.8
retains most of the polarization of +1 -jet signal while
suppressing the polarization of -1 -jet background and practically
eliminating the fake background. This can be utilized to extract the
charged Higgs signal. It can be also utilized to extract the SUSY signal in the
stau NLSP region, and in particular the stau co-annihilaton region.Comment: 8 pages, 9 figures; Fig.8 and Fig.9 are replaced, published in
"Physics at the Large Hadron Collider", A Platinum Jubilee Special Issue of
the Indian National Science Academy, Springer (2009) p 20
Tendency to Maximum Complexity in a Non-Equilibrium Isolated System
The time evolution equations of a simplified isolated ideal gas, the
"tetrahe- dral" gas, are derived. The dynamical behavior of the LMC complexity
[R. Lopez-Ruiz, H. L. Mancini, and X. Calbet, Phys. Lett. A 209, 321 (1995)] is
studied in this system. In general, it is shown that the complexity remains
within the bounds of minimum and maximum complexity. We find that there are
certain restrictions when the isolated "tetrahedral" gas evolves towards
equilibrium. In addition to the well-known increase in entropy, the quantity
called disequilibrium decreases monotonically with time. Furthermore, the
trajectories of the system in phase space approach the maximum complexity.Comment: 22 pages, 0 figures. Published in Phys. Rev. E 63, 066116(9) (2001
Back reaction in the formation of a straight cosmic string
A simple model for the formation of a straight cosmic string, wiggly or
unperturbed is considered. The gravitational field of such string is computed
in the linear approximation. The vacuum expectation value of the stress tensor
of a massless scalar quantum field coupled to the string gravitational field is
computed to the one loop order. Finally, the back-reaction effect on the
gravitational field of the string is obtained by solving perturbatively the
semiclassical Einstein's equations.Comment: 29 pages, LaTeX, no figures. A postcript version can be obtained from
anonymous ftp at ftp://ftp.ifae.es/preprint.f
Entanglement Creation Using Quantum Interrogation
We present some applications of high efficiency quantum interrogation
("interaction free measurement") for the creation of entangled states of
separate atoms and of separate photons. The quantum interrogation of a quantum
object in a superposition of object-in and object-out leaves the object and
probe in an entangled state. The probe can then be further entangled with other
objects in subsequent quantum interrogations. By then projecting out those
cases were the probe is left in a particular final state, the quantum objects
can themselves be left in various entangled states. In this way we show how to
generate two-, three-, and higher qubit entanglement between atoms and between
photons. The effect of finite efficiency for the quantum interrogation is
delineated for the various schemes.Comment: 7 pages, 13 figures, Submitted to PR
Adiabatic evolution of a coupled-qubit Hamiltonian
We present a general method for studying coupled qubits driven by
adiabatically changing external parameters. Extended calculations are provided
for a two-bit Hamiltonian whose eigenstates can be used as logical states for a
quantum CNOT gate. From a numerical analysis of the stationary Schroedinger
equation we find a set of parameters suitable for representing CNOT, while from
a time-dependent study the conditions for adiabatic evolution are determined.
Specializing to a concrete physical system involving SQUIDs, we determine
reasonable parameters for experimental purposes. The dissipation for SQUIDs is
discussed by fitting experimental data. The low dissipation obtained supports
the idea that adiabatic operations could be performed on a time scale shorter
than the decoherence time.Comment: 10 pages, 4 figures, to be pub.in Phys Rev
Quantum superpositions of clockwise and counterclockwise supercurrent states in the dynamics of a rf-SQUID exposed to a quantized electromagnetic field
The dynamical behavior of a superconducting quantum interference device (a
rf-SQUID) irradiated by a single mode quantized electromagnetic field is
theoretically investigated. Treating the SQUID as a flux qubit, we analyze the
dynamics of the combined system within the low lying energy Hilbert subspace
both in the asymmetric and in the symmetric SQUID potential configurations. We
show that the temporal evolution of the system is dominated by an oscillatory
behavior characterized by more than one, generally speaking, incommensurable
Rabi frequencies whose expressions are explicitly given. We find that the
external parameters may fixed in such a way to realize a control on the
dynamical replay of the total system which, for instance, may be forced to
exhibit a periodic evolution accompanied by the occurrence of an oscillatory
disappearance of entanglement between the two subsystems. We demonstrate the
possibility of generating quantum maximally entangled superpositions of the two
macroscopically distinguishable states describing clockwise and
counterclockwise supercurrents in the loop. The experimental feasibility of our
proposal is briefly discussed.Comment: 16 pages, 7 figures, submitted to PR
Determination of Food Preservatives in Orange Juice by Reversed-Phase Liquid Chromatography
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Hubble Space Telescope Imaging of Isolated Local Volume Dwarfs GALFA Dw3 and Dw4
We present observations of the dwarf galaxies GALFA Dw3 and GALFA Dw4 with the Advanced Camera for Surveys on the Hubble Space Telescope. These galaxies were initially discovered as optical counterparts to compact H i clouds in the GALFA survey. Both objects resolve into stellar populations which display old red giant branch (RGB), younger helium-burning, and massive main sequence stars. We use the tip of the RGB method to determine the distance to each galaxy, finding distances of Mpc and Mpc, respectively. With these distances we show that both galaxies are extremely isolated, with no other confirmed objects within ∼1.5 Mpc of either dwarf. GALFA Dw4 is also found to be unusually compact for a galaxy of its luminosity. GALFA Dw3 and Dw4 contain H ii regions with young star clusters and an overall irregular morphology; they show evidence of ongoing star formation through both ultraviolet and Hα observations and are therefore classified as dwarf irregulars (dIrrs). The star formation histories of these two dwarfs show distinct differences: Dw3 shows signs of a recently ceased episode of active star formation across the entire dwarf, while Dw4 shows some evidence for current star formation in spatially limited H ii regions. Compact H i sources offer a promising method for identifying isolated field dwarfs in the Local Volume, including GALFA Dw3 and Dw4, with the potential to shed light on the driving mechanisms of dwarf galaxy formation and evolution. © 2022. The Author(s). Published by the American Astronomical Society.Open access articleThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]