51,015 research outputs found

### Weak gravity conjecture constraints on inflation

We consider the gravitational correction to the coupling of the scalar
fields. Weak gravity conjecture says that the gravitational correction to the
running of scalar coupling should be less than the contribution from scalar
fields. For instance, a new scale $\Lambda=\lambda_4^{1/2}M_p$ sets a UV cutoff
on the validity of the effective $\lambda_4 \phi^4$ theory. Furthermore, this
conjecture implies a possible constraint on the inflation model, e.g. the
chaotic inflation model might be in the swampland.Comment: 11 pages, 3 figs; monor corrections; some clarifying remarks added
and the final version for publication in JHE

### Interacting non-minimally coupled canonical, phantom and quintom models of holographic dark energy in non-flat universe

Motivated by our recent work \cite{set1}, we generalize this work to the
interacting non-flat case. Therefore in this paper we deal with canonical,
phantom and quintom models, with the various fields being non-minimally coupled
to gravity, within the framework of interacting holographic dark energy. We
employ the holographic model of interacting dark energy to obtain the equation
of state for the holographic energy density in non-flat (closed) universe
enclosed by the event horizon measured from the sphere of horizon named $L$.Comment: 18 pages, 3 figures. Accepted for publication in IJMPD (2010

### Gravitational Correction and Weak Gravity Conjecture

We consider the gravitational correction to the running of gauge coupling.
Weak gravity conjecture implies that the gauge theories break down when the
gravitational correction becomes greater than the contribution from gauge
theories. This observation can be generalized to non-Abelian gauge theories in
diverse dimensions and the cases with large extra dimensions.Comment: 8 pages; minor correction and refs adde

### The Measure for the Multiverse and the Probability for Inflation

We investigate the measure problem in the framework of inflationary
cosmology. The measure of the history space is constructed and applied to
inflation models. Using this measure, it is shown that the probability for the
generalized single field slow roll inflation to last for $N$ e-folds is
suppressed by a factor $\exp(-3N)$, and the probability for the generalized
$n$-field slow roll inflation is suppressed by a much larger factor
$\exp(-3nN)$. Some non-inflationary models such as the cyclic model do not
suffer from this difficulty.Comment: 16 page

### Eternal Chaotic Inflation is Prohibited by Weak Gravity Conjecture

We investigate whether the eternal chaotic inflation can be achieved when the
weak gravity conjecture is taken into account. We show that even the assisted
chaotic inflation with potential $\lambda\phi^4$ or $m^2\phi^2$ can not be
eternal. The effective field theory description for the inflaton field breaks
down before inflation reaches the eternal regime. We also find that the total
number of e-folds is still bounded by the inflationary entropy for the assisted
inflation.Comment: 10 page

### Fe-based superconductors: unity or diversity?

Does the high temperature superconductivity observed in the newly discovered
iron-pnictide materials represent another example of the same essential physics
responsible for superconductivity in the cuprates, or does it embody a new
mechanism?Comment: Some minor errors in the figure and in the reference in the published
version are corrected. 2 pages, 2 figure

### Parity independence of the zero-bias conductance peak in a nanowire based topological superconductor-quantum dot hybrid device

We explore the signatures of Majorana fermions in a nanowire based
topological superconductor-quantum dot-topological superconductor hybrid device
by charge transport measurements. The device is made from an epitaxially grown
InSb nanowire with two superconductor Nb contacts on a Si/SiO$_2$ substrate. At
low temperatures, a quantum dot is formed in the segment of the InSb nanowire
between the two Nb contacts and the two Nb contacted segments of the InSb
nanowire show superconductivity due to the proximity effect. At zero magnetic
field, well defined Coulomb diamonds and the Kondo effect are observed in the
charge stability diagram measurements in the Coulomb blockade regime of the
quantum dot. Under the application of a finite, sufficiently strong magnetic
field, a zero-bias conductance peak structure is observed in the same Coulomb
blockade regime. It is found that the zero-bias conductance peak is present in
many consecutive Coulomb diamonds, irrespective of the even-odd parity of the
quasi-particle occupation number in the quantum dot. In addition, we find that
the zero-bias conductance peak is in most cases accompanied by two differential
conductance peaks, forming a triple-peak structure, and the separation between
the two side peaks in bias voltage shows oscillations closely correlated to the
background Coulomb conductance oscillations of the device. The observed
zero-bias conductance peak and the associated triple-peak structure are in line
with the signatures of Majorana fermion physics in a nanowire based topological
superconductor-quantum dot-topological superconductor system, in which the two
Majorana bound states adjacent to the quantum dot are hybridized into a pair of
quasi-particle states with finite energies and the other two Majorana bound
states remain as the zero-energy modes located at the two ends of the entire
InSb nanowire.Comment: 6 pages, 4 figure

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