8,773 research outputs found
Closed strings from decaying D-branes
We compute the emission of closed string radiation from homogeneous rolling
tachyons. For an unstable decaying D-brane the radiated energy is infinite
to leading order for and finite for . The closed string state
produced by a decaying brane is closely related to the state produced by
D-instantons at a critical Euclidean distance from . In the case of a D0
brane one can cutoff this divergence so that we get a finite energy final state
which would be the state that the brane decays into.Comment: harvmac, 30 pages, 2 figures. v3: Improved discussion for non compact
brane
Topological and differentiable rigidity of submanifolds in space forms
Let be an -dimensional simply connected space form with
nonnegative constant curvature . We prove that if is a compact
submanifold in , and if where is the mean
curvature of , then is homeomorphic to a sphere. We also show that the
pinching condition above is sharp. Moreover, we obtain a new differentiable
sphere theorem for submanifolds with positive Ricci curvature.Comment: 12 page
Production of doubly heavy baryons via Higgs boson decays
We systematically analyzed the production of semi-inclusive doubly heavy
baryons (, and ) for the process through four main Higgs decay
channels within the framework of non-relativistic QCD. The contributions from
the intermediate diquark states, ,
, , , and , have been taken into consideration.
The differential distributions and three main sources of the theoretical
uncertainties have been discussed. At the High Luminosity Large Hadron
Collider, there will be about 0.43 events of ,
6.32 events of and 0.28 events of
produced per year. There are fewer events produced at the Circular Electron
Positron Collider and the International Linear Collider, about events of , events of and
events of in operation.Comment: 15 pages, 3 figures, 7 table
Stochastic Dynamics of Electrical Membrane with Voltage-Dependent Ion Channel Fluctuations
Brownian ratchet like stochastic theory for the electrochemical membrane
system of Hodgkin-Huxley (HH) is developed. The system is characterized by a
continuous variable , representing mobile membrane charge density, and
a discrete variable representing ion channel conformational dynamics. A
Nernst-Planck-Nyquist-Johnson type equilibrium is obtained when multiple
conducting ions have a common reversal potential. Detailed balance yields a
previously unknown relation between the channel switching rates and membrane
capacitance, bypassing Eyring-type explicit treatment of gating charge
kinetics. From a molecular structural standpoint, membrane charge is a
more natural dynamic variable than potential ; our formalism treats
-dependent conformational transition rates as intrinsic
parameters. Therefore in principle, vs. is experimental
protocol dependent,e.g., different from voltage or charge clamping
measurements. For constant membrane capacitance per unit area and
neglecting membrane potential induced by gating charges, , and
HH's formalism is recovered. The presence of two types of ions, with different
channels and reversal potentials, gives rise to a nonequilibrium steady state
with positive entropy production . For rapidly fluctuating channels, an
expression for is obtained.Comment: 8 pages, two figure
Teleportation of an arbitrary multipartite state via photonic Faraday rotation
We propose a practical scheme for deterministically teleporting an arbitrary
multipartite state, either product or entangled, using Faraday rotation of the
photonic polarization. Our scheme, based on the input-output process of
single-photon pulses regarding cavities, works in low-Q cavities and only
involves virtual excitation of the atoms, which is insensitive to both cavity
decay and atomic spontaneous emission. Besides, the Bell-state measurement is
accomplished by the Faraday rotation plus product-state measurements, which
could much relax the experimental difficulty to realize the Bell-state
measurement by the CNOT operation.Comment: 11 pages, 2 figures
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