9,772 research outputs found
Leptoquark patterns unifying neutrino masses, flavor anomalies, and the diphoton excess
Vector leptoquarks provide an elegant solution to a series of anomalies and
at the same time generate naturally light neutrino masses through their mixing
with the standard model Higgs boson. We present a simple Froggatt-Nielsen model
to accommodate the B physics anomalies and , neutrino masses, and
the GeV diphoton excess in one cohesive framework adding only two vector
leptoquarks and two singlet scalar fields to the standard model field content.Comment: 12 pages, 10 figures; final version published in PR
The reduction of the closest disentangled states
We study the closest disentangled state to a given entangled state in any
system (multi-party with any dimension). We obtain the set of equations the
closest disentangled state must satisfy, and show that its reduction is
strongly related to the extremal condition of the local filtering on each
party. Although the equations we obtain are not still tractable, we find some
sufficient conditions for which the closest disentangled state has the same
reduction as the given entangled state. Further, we suggest a prescription to
obtain a tight upper bound of the relative entropy of entanglement in two-qubit
systems.Comment: a crucial error was correcte
A new emerging oral infection: Raoultella planticola in a boy with haematological malignancy
BACKGROUND: Oral mucositis is a common complication in pediatric cancer patients, affecting up to 80% of children. Due to neutropenia and disruption of the mucosal barrier, chemotherapy-induced oral mucositis is often complicated by super-infections.
CASE REPORT: A 16-years old male with stage 3 Burkitt's lymphoma developed chemotherapy induced oral mucositis grade 3 (according to WHO scale). Ulcers were quickly growing (reaching a maximum diameter of 3 cm) and became greyish in colour, resulting in dysphagia and pain. A swab of the lesions was taken and microbiological tests were performed. The sample grew for Raoultella planticola, an encapsulated Gram-negative bacterium whose full pathogenic potential still needs to be defined.
TREATMENT: The patient received antibiotic combination therapy with Amikacin and Ceftazidime for 8 days. Complete healing of the lesions and resolution of the symptoms were reached and he completed his antineoplastic therapy without further complications.
FOLLOW-UP: Twelve months after the infection, he is alive and well, with no oral complaints.
CONCLUSION: This is the first report of a Raoultella planticola infection in a patient with chemotherapy induced oral mucositis. This type of infection must be added to the list of organisms to be considered when caring for these patients
Influence of symmetry and Coulomb-correlation effects on the optical properties of nitride quantum dots
The electronic and optical properties of self-assembled InN/GaN quantum dots
(QDs) are investigated by means of a tight-binding model combined with
configuration interaction calculations. Tight-binding single particle wave
functions are used as a basis for computing Coulomb and dipole matrix elements.
Within this framework, we analyze multi-exciton emission spectra for two
different sizes of a lens-shaped InN/GaN QD with wurtzite crystal structure.
The impact of the symmetry of the involved electron and hole one-particle
states on the optical spectra is discussed in detail. Furthermore we show how
the characteristic features of the spectra can be interpreted using a
simplified Hamiltonian which provides analytical results for the interacting
multi-exciton complexes. We predict a vanishing exciton and biexciton ground
state emission for small lens-shaped InN/GaN QDs. For larger systems we report
a bright ground state emission but with drastically reduced oscillator
strengths caused by the quantum confined Stark effect.Comment: 15 pages, 17 figure
Generation of energy selective excitations in quantum Hall edge states
We operate an on-demand source of single electrons in high perpendicular
magnetic fields up to 30T, corresponding to a filling factor below 1/3. The
device extracts and emits single charges at a tunable energy from and to a
two-dimensional electron gas, brought into well defined integer and fractional
quantum Hall (QH) states. It can therefore be used for sensitive electrical
transport studies, e.g. of excitations and relaxation processes in QH edge
states
Structure of scalar mesons and the Higgs sector of strong interaction
The scalar mesons , , and
together with the pseudo Goldstone bosons , , and may be
considered as the Higgs sector of strong interaction. After a long time of
uncertainty about the internal structure of the scalar mesons there now seems
to be consistency which is in line with the major parts of experimental
observations. Great progress has been made by introducing the unified model of
Close and T\"ornqvist. This model states that mesons below 1 GeV may be
understood as in S-wave with some in P-wave in the
center, further out they rearrange as and finally as meson-meson
states. The P-wave component inherent in the structure of the neutral scalar
mesons can be understood as a doorway state for the formation of the scalar
meson via two-photon fusion, whereas in nucleon Compton scattering these P-wave
components serve as intermediate states. The masses of the scalar mesons are
predicted in terms of spontaneous and explicit symmetry breaking.Comment: 5 figure
Entropic bounds on coding for noisy quantum channels
In analogy with its classical counterpart, a noisy quantum channel is
characterized by a loss, a quantity that depends on the channel input and the
quantum operation performed by the channel. The loss reflects the transmission
quality: if the loss is zero, quantum information can be perfectly transmitted
at a rate measured by the quantum source entropy. By using block coding based
on sequences of n entangled symbols, the average loss (defined as the overall
loss of the joint n-symbol channel divided by n, when n tends to infinity) can
be made lower than the loss for a single use of the channel. In this context,
we examine several upper bounds on the rate at which quantum information can be
transmitted reliably via a noisy channel, that is, with an asymptotically
vanishing average loss while the one-symbol loss of the channel is non-zero.
These bounds on the channel capacity rely on the entropic Singleton bound on
quantum error-correcting codes [Phys. Rev. A 56, 1721 (1997)]. Finally, we
analyze the Singleton bounds when the noisy quantum channel is supplemented
with a classical auxiliary channel.Comment: 20 pages RevTeX, 10 Postscript figures. Expanded Section II, added 1
figure, changed title. To appear in Phys. Rev. A (May 98
Strengthened Lindblad inequality: applications in non equilibrium thermodynamics and quantum information theory
A strengthened Lindblad inequality has been proved. We have applied this
result for proving a generalized -theorem in non equilibrium thermodynamics.
Information processing also can be considered as some thermodynamic process.
From this point of view we have proved a strengthened data processing
inequality in quantum information theory.Comment: 7 pages, revte
Simple Realization Of The Fredkin Gate Using A Series Of Two-body Operators
The Fredkin three-bit gate is universal for computational logic, and is
reversible. Classically, it is impossible to do universal computation using
reversible two-bit gates only. Here we construct the Fredkin gate using a
combination of six two-body reversible (quantum) operators.Comment: Revtex 3.0, 7 pages, 3 figures appended at the end, please refer to
the comment lines at the beginning of the manuscript for reasons of
replacemen
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