9,841 research outputs found
Bosonic stimulation of cold 1s excitons into a harmonic potential minimum in CuO
Density distribution of cold exciton clouds generated into a strain-induced
potential well by two-photon excitation in CuO is studied at 2 K. We find
that an anomalous spike, which can be interpreted as accumulation of the
excitons into the ground state, emerges at the potential minimum. The
accumulation can be due to stimulated scattering of cold excitons, mediated by
acoustic phonon emission. Possibility of the formation of the thermodynamic
Bose-Einstein condensate of paraexcitons has been discussed.Comment: Submitted to Solid State Communications on 17 December, 200
Higher Order Bose-Einstein Correlations test the Gaussian Density Matrix Approach
A multiparticle system produced by a large number of independent sources is
described by a gaussian density matrix W. All theoretical approach to
Bose-Einstein Correlatios Cn in high energy physics use this form for W. One of
the most salient consequences of this form is the fact that all higher order
(n>2) moments of the current distribution can be expressed in terms of the
first two. We test this property by comparing the data on C2(Q^2), C3(Q^2) and
C4(Q^2) from pion-p and K-p reactions at 250 GeV/c with the predictions of a
general quantum statistical space-time approach. Even a simplified version of
such approach can account for the data. Previous attempts along these lines,
which did not use the space-time approach, met with difficulties.Comment: 17 pages (including one Table) and 2 figures. To appear in Physics
Letters B (PLB 13397
Pretext, Reality, and Verisimilitude: Truth-Seeking in the Supreme Court
The assault on truth in recent public discourse makes it especially important that judicial decisions about Executive actions reflect the world as it is. Judges should not assume some idealized reality where good faith prevails, the motives of public officials are above reproach, and administrative processes are presumptively regular. Unfortunately, however, the Supreme Court has acted on naïve or counterfactual assumptions that limit judicial review of administrative or Presidential action. Such intentional judicial blindness or suspension of justified disbelief—such lack of verisimilitude—can sow doubt regarding the Court’s candor and impartiality.
In analyzing the Court’s fealty to objective reality in its review of Executive actions, this Article focuses primarily on two Supreme Court decisions: the Travel Ban Case and the Census Case. These decisions illustrate how the mode of judicial review can influence verisimilitude. In the Travel Ban Case, the Court refused to look behind an implausible explanation of the government’s actions, a paradigm judicial departure from verisimilitude inimical to the legitimacy of the Court. The Census Case is a less direct assault on objective reality, as the Court ultimately did examine the truthfulness of the government’s justifications. But it did so in a manner that does not manifest a vital commitment to truth.
This Article will also touch upon a third case: U.S. Department of Homeland Security v. Regents of the Univ. of Cal. (the DACA Case). The DACA Case did not challenge objective reality but on the contrary insisted that agencies provide the actual reasoning behind their decisions rather than justifications they thought of later, even if those justifications were otherwise valid. The case thus reinforces the importance of candor and accuracy.
A key lesson from these cases is that to preserve its legitimacy, the Court should abandon or modify doctrines that cede judicial review of national security issues, limit consideration of `pretext, decline to assess the intent of government actors, and indulge a presumption of regularity for administrative determinations. These reforms are achievable without a major overhaul of administrative law standards
Trapping of ultracold polar molecules with a Thin Wire Electrostatic Trap
We describe the realization of a dc electric-field trap for ultracold polar
molecules, the thin-wire electrostatic trap (TWIST). The thin wires that form
the electrodes of the TWIST allow us to superimpose the trap onto a
magneto-optical trap (MOT). In our experiment, ultracold polar NaCs molecules
in their electronic ground state are created in the MOT via photoassociation,
achieving a continuous accumulation in the TWIST of molecules in low-field
seeking states. Initial measurements show that the TWIST trap lifetime is
limited only by the background pressure in the chamber.Comment: 4 pages, 3 figure
Hadron Masses and Screening from AdS Wilson Loops
We show that in strongly coupled N=4 SYM the binding energy of a heavy and a
light quark is independent of the strength of the coupling constant. As a
consequence we are able to show that in the presence of light quarks the analog
of the QCD string can snap and color charges are screened. The resulting
neutral mesons interact with each other only via pion exchange and we estimate
the massesComment: 4 pages, revte
Oscillations of solar and atmospheric neutrinos
Motivated by recent results from SuperKamiokande, we study both solar and
atmospheric neutrino fluxes in the context of oscillations of the three known
neutrinos. We aim at a global view which identifies the various possibilities,
rather than attempting the most accurate determination of the parameters of
each scenario. For solar neutrinos we emphasise the importance of performing a
general analysis, independent of any particular solar model and we consider the
possibility that any one of the techniques --- chlorine, gallium or water
Cerenkov --- has a large unknown systematic error, so that its results should
be discarded. The atmospheric neutrino anomaly is studied by paying special
attention to the ratios of upward and downward going nu_e and nu_mu fluxes.
Both anomalies can be described in a minimal scheme where the respective
oscillation frequencies are widely separated or in non-minimal schemes with two
comparable oscillation frequencies. We discuss explicit forms of neutrino mass
matrices in which both atmospheric and solar neutrino fluxes are explained. In
the minimal scheme we identify only two `zeroth order' textures that can result
from unbroken symmetries. Finally we discuss experimental strategies for the
determination of the various oscillation parameters.Comment: 20 pages, 7 figures. Final version: one reference added; fit of
atmospheric neutrinos improve
Unification in models with replicated gauge groups
We examine unification of gauge couplings in four dimensional renormalizable
gauge theories inspired by the latticized (deconstructed) SM or MSSM in five
dimensions. The models are based on replicated gauge groups, spontaneously
broken to the diagonal subgroup. The analysis is performed at one-loop level,
with the contribution from the heavy vector bosons included, and compared with
the analogous results in the SM or MSSM. Unification at or above the diagonal
breaking scale is discussed. We find that in the considered class of extensions
of the SM(MSSM) unification is possible for a wide range of unification scales
and with the similar accuracy as in the SM(MSSM). Unification above the
diagonal breaking scale is particularly attractive: it is a consequence of the
SM(MSSM) unification, but with the unification scale depending on the number of
replications of the gauge group.Comment: 19 pages, 3 figure
- …