99 research outputs found
Non-Relativistic Bose-Einstein Condensates, Kaon droplets, and Q- Balls
We note the similarity between BEC (Bose-Einstein Condensates) formed of
atoms between which we have long-range attraction (and shorter-range
repulsions) and the field theoretic "Q balls". This allows us in particular to
address the stability of various putative particle physics Q balls made of
non-relativistic bosons using variational methods of many-body physics
The BCS - BEC Crossover In Arbitrary Dimensions
Cold atom traps and certain neutron star layers may contain fermions with
separation much larger than the range of pair-wise potentials yet much shorter
than the scattering length.
Such systems can display {\em universal} characteristics independent of the
details of the short range interactions.
In particular, the energy per particle is a fraction of the Fermi
energy of the free Fermion system.
Our main result is that for space dimensions D smaller than two and larger
than four a specific extension of this problem readily yields for all
whereas is rigorously non-positive (and potentially vanishing)
for all . We discuss the D=3 case. A particular unjustified recipe
suggests in D=3.Comment: 9 pages, 1 figur
Tests of CPT
The ongoing experimental efforts in the high energy and high precision
communities keep providing evidence for CPT, a fundamental symmetry holding in
any local Lorentz invariant theory. We suggest possible interconnections
between different CPT violating parameters. Specifically, the very precise test
of CPT in the system suggests--though definitely does not
imply--that CPT violations in other observable parameters (mass, width, charge,
magnetic moments, etc.) are much smaller than the directly measured bounds.Comment: 7 pages, 1 figur
A Novel Approach to Complex Problems
A novel approach to complex problems has been previously applied to graph
classification and the graph equivalence problem. Here we consider its
applications to a wide set of NP complete problems, namely, those of finding a
subgraph g inside a graph G.Comment: 9 page
From Higgs to pions and Back -- the Unbearable Lightness of a Composite Scalar Boson at 125 GeV in Purely Vectorial Theories
We argue that the "Higgs" particle is unlikely to arise as a
fermion- antifermion composite if the underlying dynamics is a vectorial gauge
theory. The reason is that the lightest scalar in such theories is heavier than
the lightest pseudo-scalar with the mass difference being fixed by the scale of
the theory. LHC searches suggest that the scale of any new physics, including
that of a putative new theory dynamically generating the 125 GeV "Higgs"
particle, is relatively high . Also the LHC analysis
suggests that it is {\it scalar} namely rather than pseudo-scalar.
Thus it is unlikely that the "Higgs" could arise as a composite in such
theories- though it will arise in special cases when the underlying binding
gauge group is real as a fermion-fermion bound state.
The direct considerations of the various two point functions in the large
limit presented below- suggest that massless pseudo-scalars, but not any
other anomalously light meson, arise as composites of massless fermions say the
massless u and quarks in QCD. These massless pions manifest the
spontaneous breaking of the global axial symmetry in QCD with the pions being
(pseudo) Nambu Goldstone Bosons. This offers a different insight into SXSB in
QCD and most other confining non-abelian gauge vectorial gauge theory.
Specifically we consider the euclidean two point functions for
asymptotic expressed as a sum over fermionic paths. We conjecture that
for the pseudo-scalar two point function - and for that case only- self
retracing paths and closely related paths make in this limit a positive,
coherent and dominant contribution, a contribution which evades the generic
asymptotic exponential fall-off and allows the lightest pseudoscalars to be
massless. The same arguments imply that the scalars are very massive
Are Bulk Axions in Models with Extra, Large, Compact Dimensions Observable?
The high degeneracy of KK modes in models which have bulk axions moving in
some extra, compact dimensions which are larger than O (Angstrom)strongly
tightens the supernova upper bounds on the axion photon coupling making axions
practically unobservable. Conversely, discovering axions directly or indirectly
will exclude such models. These drastic conclusions are avoided if the
supernova and bounds from solar axion searches are relaxed.Comment: 7 pages; cross-reference with Astrophysic
Early inflation induced gravity waves can restrict Astro-Particle physics
In this paper, we discuss limits on various astro-particle scenarios if the
scale \textit{and} the reheat temperature of the last relevant inflation were
very high. While the observed "B" like pattern of polarizations of the CMB
suggest a very high () scale of a primordial (which motivated
this work initially) and may reflect effects of dust, we believe that
addressing these issues is nonetheless very useful. We recall the potential
difficulties with various topological defects - monopoles, strings and domain
walls generated at the SSB (spontaneous symmetry breaking) of various gauge
symmetries. The main part of the paper is devoted to discussing difficulties
with long-lived heavy particles, which could be dark matter but cannot
efficiently annihilate to the required residual density because of basic
S-Matrix unitarity/analyticity limits. We indicate in simple terms yet in some
detail how the WIMP miracle occurs at and how the axiomatic
upper bound presently updated to was originally derived by
Greist and Kamionokowski. We also argue that generically we expect the stronger
bound to hold. We then elaborate on the pure particle
physics approaches aiming to enhance the annihilation and evade the bounds. We
find that the only and in fact very satisfactory way of doing this requires
endowing the particles with gauge interactions with a confinement scale lower
than . We also comment on models with light dark matter, which
was supposed to be frozen in via out-of equilibrium processes so as to have the
right relic densities pointing out that in many such cases \textit{very} low
reheat temperatures are indeed required and speculate on the large desert
scenario of particle physics. Most of what we discuss is not new but was not
presented in a coherent fashion
Some Comments on Possible Preferred Directions for the SETI Search
The search for extraterrestrial intelligence by looking for signals from
advanced technological civilizations has been ongoing for some decades. We
suggest that it could possibly be made more efficient by focusing on stars from
which the solar system can be observed via mini-eclipsings of the Sun by
transiting planets.Comment: 12 page
Dark Matter Tomography
We consider Wimp annihilations into monochromatic and continuous 's
and the angular distribution of the resulting gammas. We discuss how the WIMP
density profile can be reconstructed from the angular dependence of the photon
flux.Comment: 6 pages, 1 figur
Is the Froissart bound relevant for the total pp cross section at s=(14 TeV)^2?
The Froissart bound limmits the asymptotic s->infinity behavior of
crossections by (\pi/t_0) ln ^2 (s/{(s_0)} where t_0 is the lightest exchanged
particle, or more generally the nearest ssingularity, in the t channel. We
suggest that in comparing this bound with data at energies less than those of
LHC, gluebaall masses raather than the small pion mass should be used for
(t_0)^{1/2}.Comment: 17 Pages, 1 Figur
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