1,890 research outputs found
Violation of the Luttinger sum rule within the Hubbard model on a triangular lattice
The frequency-moment expansion method is developed to analyze the validity of
the Luttinger sum rule within the Mott-Hubbard insulator, as represented by the
generalized Hubbard model at half filling and large . For the particular
case of the Hubbard model with nearest-neighbor hopping on a triangular lattice
lacking the particle-hole symmetry results reveal substantial violation of the
sum rule.Comment: 4 pages, 2 figure
Towards the realistic fermion masses with a single family in extra dimensions
In a class of multidimensional models, topology of a thick brane provides
three chiral fermionic families with hierarchical masses and mixings in the
effective four-dimensional theory, while the full model contains a single
vector-like generation. We carry out numerical simulations and reproduce all
known Standard Model fermion masses and mixings in one of these models.Comment: 12 pages, 2 figures, uses JHEP3.cls. Some minor corrections are mad
The Plasma Puddle as a Perturbative Black Hole
We argue that the weak coupling regime of a large N gauge theory in the Higgs
phase contains black hole-like objects. These so-called ``plasma puddles'' are
meta-stable lumps of hot plasma lying in locally un-Higgsed regions of space.
They decay via O(1/N) thermal radiation and, perhaps surprisingly, absorb all
incident matter. We show that an incident particle of energy E striking the
plasma puddle will shower into an enormous number of decay products whose
multiplicity grows linearly with E, and whose average energy is independent of
E. Once these ultra-soft particles reach the interior they are thermalized by
the plasma within, and so the object appears ``black.'' We determine some gross
properties like the size and temperature of the the plasma puddle in terms of
fundamental parameters in the gauge theory. Interestingly, demanding that the
plasma puddle emit thermal Hawking radiation implies that the object is black
(i.e. absorbs all incident particles), which implies classical stability, which
implies satisfaction of the Bekenstein entropy bound. Because of the AdS/CFT
duality and the many similarities between plasma puddles and black holes, we
conjecture that black objects are a robust feature of quantum gravity.Comment: 23 pages, 3 figures, V2: minor changes, ref added, appendix A.5 moved
to body of pape
CP violation in 5D Split Fermions Scenario
We give a new configuration of split fermion positions in one extra dimension
with two different Yukawa coupling strengths for up-type, , and down-type,
, quarks at . The new configurations can give enough
CP violating (CPV) phase for accommodating all currently observed CPV
processes. Therefore, a 5D standard model with split fermions is viable. In
addition to the standard CKM phase, new CPV sources involving Kaluza-Klein(KK)
gauge bosons coupling which arise from the fact that unitary rotation which
transforms weak eigenstates into their mass eigenstates only holds for the zero
modes which are the SM fields and not for the KK excitations. We have examined
the physics of kaon, neutron, and mesons and found the most stringent
bound on the size of the extra dimension comes from .
Moreover, it depends sensitively on the width, , of the Gaussian
wavefunction in the extra dimension used to describe of the fermions. When
, the constraint will be lifted due to GIM suppression on the
flavor changing neutral current(FCNC) and CPV couplings.Comment: 24 pages, 8 figure
Extracting the bulk metric from boundary information in asymptotically AdS spacetimes
We use geodesic probes to recover the entire bulk metric in certain
asymptotically AdS spacetimes. Given a spectrum of null geodesic endpoints on
the boundary, we describe two remarkably simple methods for recovering the bulk
information. After examining the issues which affect their application in
practice, we highlight a significant advantage one has over the other from a
computational point of view, and give some illustrative examples. We go on to
consider spacetimes where the methods cannot be used to recover the complete
bulk metric, and demonstrate how much information can be recovered in these
cases.Comment: 33 pages, 11 figures; v2 references adde
A Lattice Formulation of Super Yang-Mills Theories with Exact Supersymmetry
We construct super Yang-Mills theories with extended supersymmetry on
hypercubic lattices of various dimensions keeping one or two supercharges
exactly. Gauge fields are represented by ordinary unitary link variables, and
the exact supercharges are nilpotent up to gauge transformations. Among the
models, we show that the desired continuum theories are obtained without any
fine tuning of parameters for the cases in two-dimensions.Comment: 29 pages, 1 figure, LaTeX, (v2) problem on degenerate vacua
discussed, renormalization arguments modified, (v3) explanations and
references added, published version in JHE
Embedding of theories with SU(2|4) symmetry into the plane wave matrix model
We study theories with SU(2|4) symmetry, which include the plane wave matrix
model, 2+1 SYM on RxS^2 and N=4 SYM on RxS^3/Z_k. All these theories possess
many vacua. From Lin-Maldacena's method which gives the gravity dual of each
vacuum, it is predicted that the theory around each vacuum of 2+1 SYM on RxS^2
and N=4 SYM on RxS^3/Z_k is embedded in the plane wave matrix model. We show
this directly on the gauge theory side. We clearly reveal relationships among
the spherical harmonics on S^3, the monopole harmonics and the harmonics on
fuzzy spheres. We extend the compactification (the T-duality) in matrix models
a la Taylor to that on spheres.Comment: 56 pages, 6 figures, v2:a footnote and references added, section 5.2
improved, typos corrected, v3:typos corrected, v4: some equations are
corrected, eq.(G.2) is added, conclusion is unchange
Supersymmetry breaking in a warped slice with Majorana-type masses
We study the five-dimensional (5D) supergravity compactified on an orbifold
S^1/Z_2, where the U(1)_R symmetry is gauged by the graviphoton with Z_2-even
coupling. In contrast to the case of gauging with Z_2-odd coupling, this class
of models has Majorana-type masses and allows the Scherk-Schwarz (SS) twist
even in the warped spacetime. Starting from the off-shell formulation, we show
that the supersymmetry is always broken in an orbifold slice of AdS_5,
irrespective of the value of the SS twist parameter. We analyze the spectra of
gaugino and gravitino in such background, and find the SS twist can provide
sizable effects on them in the small warping region.Comment: 1+20 pages, 6 figure
A renormalisation group approach to two-body scattering in the presence of long-range forces
We apply renormalisation-group methods to two-body scattering by a
combination of known long-range and unknown short-range potentials. We impose a
cut-off in the basis of distorted waves of the long-range potential and
identify possible fixed points of the short-range potential as this cut-off is
lowered to zero. The expansions around these fixed points define the power
countings for the corresponding effective field theories. Expansions around
nontrivial fixed points are shown to correspond to distorted-wave versions of
the effective-range expansion. These methods are applied to scattering in the
presence of Coulomb, Yukawa and repulsive inverse-square potentials.Comment: 22 pages (RevTeX), 4 figure
How to write an original article for the Journal of Orthopaedics and Traumatology
The abstract is the precise summary of the article, not a preface. As Baue wrote in a popular editorial of the Archives of Surgery in 1979, “writing a good abstract is not abstract writing” [6]. The main data have to be represented, as they allow readers to understand contents clearly. Sentences like “The paper reports...” or “The authors describe...” have to be avoided as well as any generic statements
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