2,126 research outputs found
Boundary states for a free boson defined on finite geometries
Langlands recently constructed a map that factorizes the partition function
of a free boson on a cylinder with boundary condition given by two arbitrary
functions in the form of a scalar product of boundary states. We rewrite these
boundary states in a compact form, getting rid of technical assumptions
necessary in his construction. This simpler form allows us to show explicitly
that the map between boundary conditions and states commutes with conformal
transformations preserving the boundary and the reality condition on the scalar
field.Comment: 16 pages, LaTeX (uses AMS components). Revised version; an analogy
with string theory computations is discussed and references adde
Form-factors computation of Friedel oscillations in Luttinger liquids
We show how to analytically determine for the "Friedel
oscillations" of charge density by a single impurity in a 1D Luttinger liquid
of spinless electrons.Comment: Revtex, epsf, 4pgs, 2fig
Mass Hierarchy Determination Using Neutrinos from Multiple Reactors
We report the results of Monte Carlo simulations of a medium baseline reactor
neutrino experiment. The difference in baselines resulting from the 1 km
separations of Daya Bay and Ling Ao reactors reduces the amplitudes of 1-3
oscillations at low energies, decreasing the sensitivity to the neutrino mass
hierarchy. A perpendicular detector location eliminates this effect. We
simulate experiments under several mountains perpendicular to the Daya Bay/Ling
Ao reactors, considering in particular the background from the TaiShan and
YangJiang reactor complexes. In general the hierarchy can be determined most
reliably underneath the 1000 meter mountain BaiYunZhang, which is 44.5 km from
Daya Bay. If some planned reactors are not built then nearby 700 meter
mountains at 47-51 km baselines gain a small advantage. Neglecting their low
overhead burdens, hills near DongKeng would be the optimal locations. We use a
weighted Fourier transform to avoid a spurious dependence on the high energy
neutrino spectrum and find that a neural network can extract quantities which
determine the hierarchy marginally better than the traditional RL + PV.Comment: 22 pages, added details on the neural network (journal version
Boundary bound states and boundary bootstrap in the sine-Gordon model with Dirichlet boundary conditions.
We present a complete study of boundary bound states and related boundary
S-matrices for the sine-Gordon model with Dirichlet boundary conditions. Our
approach is based partly on the bootstrap procedure, and partly on the explicit
solution of the inhomogeneous XXZ model with boundary magnetic field and of the
boundary Thirring model. We identify boundary bound states with new ``boundary
strings'' in the Bethe ansatz. The boundary energy is also computed.Comment: 25 pages, harvmac macros Report USC-95-001
Direct Calculation of Breather S Matrices
We formulate a systematic Bethe-Ansatz approach for computing bound-state
(``breather'') S matrices for integrable quantum spin chains. We use this
approach to calculate the breather boundary S matrix for the open XXZ spin
chain with diagonal boundary fields. We also compute the soliton boundary S
matrix in the critical regime.Comment: 23 pages, LaTeX, 1 eps figur
Probing Freeze-in Dark Matter via Heavy Neutrino Portal
We explore the possibility of probing freeze-in dark matter (DM) produced via
the right-handed neutrino (RHN) portal using the RHN search experiments. We
focus on a simplified framework of minimally-extended type-I seesaw model
consisting of only four free parameters, namely the RHN mass, the fermionic DM
mass, the Yukawa coupling between the DM and the RHN, and a real singlet scalar
mass. We consider two cases for the DM production either via decay of the
thermal RHN or via scattering of the bath particles mediated by the RHN. In
both cases, we show that for sub-TeV scale DM masses, the allowed model
parameter space satisfying the observed DM relic density for freeze-in scenario
falls within the reach of current and future collider, beam dump and forward
physics facilities looking for feebly-coupled heavy neutrinos.Comment: version matches journal publication, revise
Edge Critical Behaviour of the 2-Dimensional Tri-critical Ising Model
Using previous results from boundary conformal field theory and
integrability, a phase diagram is derived for the 2 dimensional Ising model at
its bulk tri-critical point as a function of boundary magnetic field and
boundary spin-coupling constant. A boundary tri-critical point separates phases
where the spins on the boundary are ordered or disordered. In the latter range
of coupling constant, there is a non-zero critical field where the
magnetization is singular. In the former range, as the temperature is lowered,
the boundary undergoes a first order transition while the bulk simultaneously
undergoes a second order transition.Comment: 6 pages, RevTex, 3 postscript figure
Neutrino mass hierarchy and octant determination with atmospheric neutrinos
The recent discovery by the Daya-Bay and RENO experiments, that \theta_{13}
is nonzero and relatively large, significantly impacts existing experiments and
the planning of future facilities. In many scenarios, the nonzero value of
\theta_{13} implies that \theta_{23} is likely to be different from \pi/4.
Additionally, large detectors will be sensitive to matter effects on the
oscillations of atmospheric neutrinos, making it possible to determine the
neutrino mass hierarchy and the octant of \theta_{23}. We show that a 50 kT
magnetized liquid argon neutrino detector can ascertain the mass hierarchy with
a significance larger than 4 sigma with moderate exposure times, and the octant
at the level of 2-3 sigma with greater exposure.Comment: 4 pages, 4 figures. Version published in Phys. Rev. Let
Boundary breathers in the sinh-Gordon model
We present an investigation of the boundary breather states of the
sinh-Gordon model restricted to a half-line. The classical boundary breathers
are presented for a two parameter family of integrable boundary conditions.
Restricting to the case of boundary conditions which preserve the \phi -->
-\phi symmetry of the bulk theory, the energy spectrum of the boundary states
is computed in two ways: firstly, by using the bootstrap technique and
subsequently, by using a WKB approximation. Requiring that the two descriptions
of the spectrum agree with each other allows a determination of the
relationship between the boundary parameter, the bulk coupling constant, and
the parameter appearing in the reflection factor derived by Ghoshal to describe
the scattering of the sinh-Gordon particle from the boundary.Comment: 16 pages amslate
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