14,947 research outputs found
Canonical, squeezed and fermionic coherent states in a right quaternionic Hilbert space with a left multiplication on it
Using a left multiplication defined on a right quaternionic Hilbert space, we
shall demonstrate that various classes of coherent states such as the canonical
coherent states, pure squeezed states, fermionic coherent states can be defined
with all the desired properties on a right quaternionic Hilbert space. Further,
we shall also demonstrate squeezed states can be defined on the same Hilbert
space, but the noncommutativity of quaternions prevents us in getting the
desired results.Comment: Conference paper. arXiv admin note: text overlap with
arXiv:1704.02946; substantial text overlap with arXiv:1706.0068
Remarks on a Proposed Super-Kamiokande Test for Quantum Gravity Induced Decoherence Effects
Lisi, Marrone, and Montanino have recently proposed a test for quantum
gravity induced decoherence effects in neutrino oscillations observed at
Super-Kamiokande. We comment here that their equations have the same
qualitative form as the energy conserving objective state vector reduction
equations discussed by a number of authors. However, using the Planckian
parameter value proposed to explain state vector reduction leads to a neutrino
oscillation effect many orders of magnitude smaller than would be detectable at
Super-Kamiokande. Similar estimates hold for the Ghirardi, Rimini, and Weber
spontaneous localization approach to state vector reduction, and our remarks
are relevant as well to proposed meson and meson tests of gravity
induced decoherence.Comment: 10 pages, plain Tex, no figure
Collapse models with non-white noises
We set up a general formalism for models of spontaneous wave function
collapse with dynamics represented by a stochastic differential equation driven
by general Gaussian noises, not necessarily white in time. In particular, we
show that the non-Schrodinger terms of the equation induce the collapse of the
wave function to one of the common eigenstates of the collapsing operators, and
that the collapse occurs with the correct quantum probabilities. We also
develop a perturbation expansion of the solution of the equation with respect
to the parameter which sets the strength of the collapse process; such an
approximation allows one to compute the leading order terms for the deviations
of the predictions of collapse models with respect to those of standard quantum
mechanics. This analysis shows that to leading order, the ``imaginary'' noise
trick can be used for non-white Gaussian noise.Comment: Latex, 20 pages;references added and minor revisions; published as J.
Phys. A: Math. Theor. {\bf 40} (2007) 15083-1509
Origin of the anomalies: the modified Heisenberg equation
The origin of the anomalies is analyzed. It is shown that they are due to the
fact that the generators of the symmetry do not leave invariant the domain of
definition of the Hamiltonian and then a term, normally forgotten in the
Heisenberg equation, gives an extra contribution responsible for the non
conservation of the charges. This explanation is equivalent to that of the
Fujikawa in the path integral formalism. Finally, this approach is applied to
the conformal symmetry breaking in two-dimensional quantum mechanics.Comment: 7 pages, LaTe
Radiative and Collisional Energy Loss, and Photon-Tagged Jets at RHIC
The suppression of single jets at high transverse momenta in a quark-gluon
plasma is studied at RHIC energies, and the additional information provided by
a photon tag is included. The energy loss of hard jets traversing through the
medium is evaluated in the AMY formalism, by consistently taking into account
the contributions from radiative events and from elastic collisions at leading
order in the coupling. The strongly-interacting medium in these collisions is
modelled with (3+1)-dimensional ideal relativistic hydrodynamics. Putting these
ingredients together with a complete set of photon-production processes, we
present a calculation of the nuclear modification of single jets and
photon-tagged jets at RHIC.Comment: 4 pages, 4 figures, contributed to the 3rd International Conference
on Hard and Electro-Magnetic Probes of High-Energy Nuclear Collisions (Hard
Probes 2008), typos corrected, published versio
The dihadron fragmentation function and its evolution
Dihadron fragmentation functions and their evolution are studied in the
process of annihilation. Under the collinear factorization
approximation and facilitated by the cut-vertex technique, the two hadron
inclusive cross section at leading order (LO) is shown to factorize into a
short distance parton cross section and a long distance dihadron fragmentation
function. We provide the definition of such a dihadron fragmentation function
in terms of parton matrix elements and derive its DGLAP evolution equation at
leading log. The evolution equation for the non-singlet quark fragmentation
function is solved numerically with a simple ansatz for the initial condition
and results are presented for cases of physical interest.Comment: 27 pages, 2 column, Revtex4, 21 figure
QCD Accurately Predicts the Induced Pseudoscalar Coupling Constant
Using chiral Ward identities of QCD, we derive a relation for the induced
pseudoscalar coupling constant which is accurate within a few percent, .Comment: 5pp, LaTeX, CRN-94/1
One-Loop QCD Mass Effects in the Production of Polarized Bottom and Top Quarks
The analytic expressions for the production cross sections of polarized
bottom and top quarks in annihilation are explicitly derived at the
one-loop order of strong interactions. Chirality-violating mass effects will
reduce the longitudinal spin polarization for the light quark pairs by an
amount of , when one properly considers the massless limit for the final
quarks. Numerical estimates of longitudinal spin polarization effects in the
processes and are presented.Comment: 17 p. (5 figs available upon request), LaTeX, MZ-TH/93-30, RAL/93-81,
FTUV/93-4
Phenomenology of Jet Quenching in Heavy Ion Collisions
We derive an analytical expression for the quenching factor in the strong
quenching limit where the spectrum of hard partons is dominated by
surface emission. We explore the phenomenological consequences of different
scaling laws for the energy loss and calculate the additional suppression of
the away-side jet.Comment: Substantially modified manuscrip
Sensation Seeking and Perceived Need for Structure Moderate Soldiers’ Well-Being Before and After Operational Deployment
This study examined associations between sensation seeking and perceived need for structure, and changes in reported well-being among deployed soldiers. Participants (n = 167) were assessed before and after a six-month deployment to south Afghanistan. Results indicated that although well-being declined in the soldier sample as a whole following deployment, the degree of decrease was significantly different among soldiers with different personality profiles. Differences were moderated by soldiers’ level of sensation seeking and perceived need for structure. Results are discussed in terms of a person-environment fit theory in the context of preparation and rehabilitation of deployed military personnel
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