951 research outputs found
1D Lieb-Liniger Bose Gas as Non-Relativistic Limit of the Sinh-Gordon Model
The repulsive Lieb-Liniger model can be obtained as the non-relativistic
limit of the Sinh-Gordon model: all physical quantities of the latter model
(S-matrix, Lagrangian and operators) can be put in correspondence with those of
the former. We use this mapping, together with the Thermodynamical Bethe Ansatz
equations and the exact form factors of the Sinh-Gordon model, to set up a
compact and general formalism for computing the expectation values of the
Lieb-Liniger model both at zero and finite temperature. The computation of
one-point correlators is thoroughly detailed and, when possible, compared with
known results in the literature.Comment: published version, 27 pages, 10 figure
Expectation Values in the Lieb-Liniger Bose Gas
Taking advantage of an exact mapping between a relativistic integrable model
and the Lieb-Liniger model we present a novel method to compute expectation
values in the Lieb-Liniger Bose gas both at zero and finite temperature. These
quantities, relevant in the physics of one-dimensional ultracold Bose gases,
are expressed by a series that has a remarkable behavior of convergence. Among
other results, we show the computation of the three-body expectation value at
finite temperature, a quantity that rules the recombination rate of the Bose
gas.Comment: Published version. Selected for the December 2009 issue of Virtual
Journal of Atomic Quantum Fluid
Local Correlations in the Super Tonks-Girardeau Gas
We study the local correlations in the super Tonks-Girardeau gas, a highly
excited, strongly correlated state obtained in quasi one-dimensional Bose gases
by tuning the scattering length to large negative values using a
confinement-induced resonance. Exploiting a connection with a relativistic
field theory, we obtain results for the two-body and three-body local
correlators at zero and finite temperature. At zero temperature our result for
the three-body correlator agrees with the extension of the results of Cheianov
et al. [Phys. Rev. A 73, 051604(R) (2006)], obtained for the ground-state of
the repulsive Lieb-Liniger gas, to the super Tonks-Girardeau state. At finite
temperature we obtain that the three-body correlator has a weak dependence on
the temperature up to the degeneracy temperature. We also find that for
temperatures larger than the degeneracy temperature the values of the
three-body correlator for the super Tonks-Girardeau gas and the corresponding
repulsive Lieb-Liniger gas are rather similar even for relatively small
couplings
Indication of electron neutrino appearance from an accelerator-produced off-axis muon neutrino beam
The T2K experiment observes indications of nu(mu) -> nu(mu) e appearance in data accumulated with 1.43 x 10(20) protons on target. Six events pass all selection criteria at the far detector. In a three-flavor neutrino oscillation scenario with |Delta m(23)(2)| = 2.4 x 10(-3) eV(2), sin(2)2 theta(23) = 1 and sin(2)2 theta(13) = 0, the expected number of such events is 1.5 +/- 0.3(syst). Under this hypothesis, the probability to observe six or more candidate events is 7 x 10(-3), equivalent to 2.5 sigma significance. At 90% C.L., the data are consistent with 0.03(0.04) < sin(2)2 theta(13) < 0.28(0.34) for delta(CP) = 0 and a normal (inverted) hierarchy
A clinical trial combining donor bone marrow infusion and heart transplantation: intermediate-term results.
BACKGROUND: Donor chimerism (the presence of donor cells of bone marrow origin) is present for years after transplantation in recipients of solid organs. In lung recipients, chimerism is associated with a lower incidence of chronic rejection. To augment donor chimerism with the aim to enhance graft acceptance and to reduce immunosuppression, we initiated a trial combining infusion of donor bone marrow with heart transplantation. Reported herein are the intermediate-term results of this ongoing trial. METHODS: Between September 1993 and August 1998, 28 patients received concurrent heart transplantation and infusion of donor bone marrow at 3.0 x 10(8) cells/kg (study group). Twenty-four contemporaneous heart recipients who did not receive bone marrow served as controls. All patients received an immunosuppressive regimen consisting of tacrolimus and steroids. RESULTS: Patient survival was similar between the study and control groups (86% and 87% at 3 years, respectively). However, the proportion of patients free from grade 3A rejection was higher in the study group (64% at 6 months) than in the control group (40%; P =.03). The prevalence of coronary artery disease was similar between the two groups (freedom from disease at 3 years was 78% in study patients and 69% in controls). Similar proportions of study (18%) and control (15%) patients exhibited in vitro evidence of donor-specific hyporesponsiveness. CONCLUSIONS: The infusion of donor bone marrow reduces the rate of acute rejection in heart recipients. Donor bone marrow may play an important role in strategies aiming to enhance the graft acceptance
Pause behaviour within reformulations and the proficiency level of second language learners of English
This research reports on a quantitative analysis of the combination of two types of disfluency, reformulations and pauses, in the speech of lower intermediate and advanced speakers of English as a second language (L2). The present study distinguishes between corrections and false starts within the category of reformulations as well as between silent and filled pauses. It focuses on the extent to which pause behavior within reformulations varies according to the stage of L2 development and the type of reformulation used. An analysis was made of 56 L2 speakers’ 2-min monologues. The results showed that lower intermediate and advanced speakers differed on the frequency of silent pauses inserted in corrections but not on their frequency in false starts. This suggests that false starts depend less on proficiency level, and may reflect temporary problems with conceptual encoding or extralinguistic factors that contribute to the efficacy of L2 production rather than difficulties with linguistic processing per se. The frequency of silent pauses rather than silent pause duration or the frequency and duration of filled pauses appeared to be the only marker to differentiate between false starts and corrections across the two proficiency groups
Quantum Quenches in Integrable Field Theories
We study the non equilibrium time evolution of an integrable field theory in
1+1 dimensions after a sudden variation of a global parameter of the
Hamiltonian. For a class of quenches defined in the text, we compute the long
times limit of the one point function of a local operator as a series of form
factors. Even if some subtleties force us to handle this result with care,
there is a strong evidence that for long times the expectation value of any
local operator can be described by a generalized Gibbs ensemble with a
different effective temperature for each eigenmode
On Form Factors in nested Bethe Ansatz systems
We investigate form factors of local operators in the multi-component Quantum
Non-linear Schr\"odinger model, a prototype theory solvable by the so-called
nested Bethe Ansatz. We determine the analytic properties of the infinite
volume form factors using the coordinate Bethe Ansatz solution and we establish
a connection with the finite volume matrix elements. In the two-component
models we derive a set of recursion relations for the "magnonic form factors",
which are the matrix elements on the nested Bethe Ansatz states. In certain
simple cases (involving states with only one spin-impurity) we obtain explicit
solutions for the recursion relations.Comment: 34 pages, v2 (minor modifications
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