3,647 research outputs found
Exact Potts Model Partition Functions for Strips of the Honeycomb Lattice
We present exact calculations of the Potts model partition function
for arbitrary and temperature-like variable on -vertex
strip graphs of the honeycomb lattice for a variety of transverse widths
equal to vertices and for arbitrarily great length, with free
longitudinal boundary conditions and free and periodic transverse boundary
conditions. These partition functions have the form
, where
denotes the number of repeated subgraphs in the longitudinal direction. We give
general formulas for for arbitrary . We also present plots of
zeros of the partition function in the plane for various values of and
in the plane for various values of . Explicit results for partition
functions are given in the text for (free) and (cylindrical),
and plots of partition function zeros are given for up to 5 (free) and
(cylindrical). Plots of the internal energy and specific heat per site
for infinite-length strips are also presented.Comment: 39 pages, 34 eps figures, 3 sty file
Little Higgs Models and Precision Electroweak Data
We study the low energy limit of Little Higgs models. The method consists in
eliminating the heavy fields using their classical equations of motion in the
infinite mass limit. After the elimination of the heavy degrees of freedom we
can directly read off deviations from the precision electroweak data. We also
examine the effects on the low energy precision experiments.Comment: Misprint in eps3 for the custodial model corrected and additional
discussion of the triplet higg
The g-2 of the Muon in Localized Gravity Models
The (g-2) of the muon is well known to be an important model building
constraint on theories beyond the Standard Model. In this paper, we examine the
contributions to arising in the Randall-Sundrum model of localized
gravity for the case where the Standard Model gauge fields and fermions are
both in the bulk. Using the current experimental world average measurement for
, we find that strong constraints can be placed on the mass of the
lightest gauge Kaluza-Klein excitation for a narrow part of the allowed range
of the assumed universal 5-dimensional fermion mass parameter, . However,
employing both perturbativity and fine-tuning constraints we find that we can
further restrict the allowed range of the parameter to only one fourth of
its previous size. The scenario with the SM in the RS bulk is thus tightly
constrained, being viable for only a small region of the parameter space.Comment: 16 pages, 2 figs, LaTex, Additional discussion adde
Potts model on recursive lattices: some new exact results
We compute the partition function of the Potts model with arbitrary values of
and temperature on some strip lattices. We consider strips of width
, for three different lattices: square, diced and `shortest-path' (to be
defined in the text). We also get the exact solution for strips of the Kagome
lattice for widths . As further examples we consider two lattices
with different type of regular symmetry: a strip with alternating layers of
width and , and a strip with variable width. Finally we make
some remarks on the Fisher zeros for the Kagome lattice and their large
q-limit.Comment: 17 pages, 19 figures. v2 typos corrected, title changed and
references, acknowledgements and two further original examples added. v3 one
further example added. v4 final versio
A Tight Karp-Lipton Collapse Result in Bounded Arithmetic
Cook and Krajíček [9] have obtained the following Karp-Lipton result in bounded arithmetic: if the theory proves , then collapses to , and this collapse is provable in . Here we show the converse implication, thus answering an open question from [9]. We obtain this result by formalizing in a hard/easy argument of Buhrman, Chang, and Fortnow [3]. In addition, we continue the investigation of propositional proof systems using advice, initiated by Cook and Krajíček [9]. In particular, we obtain several optimal and even p-optimal proof systems using advice. We further show that these p-optimal systems are equivalent to natural extensions of Frege systems
Singlet Fermionic Dark Matter explains DAMA signal
It has been suggested that, considering channeling effect, the order of a few
GeV dark matters which are elastically scattered from detector nuclei might be
plausible candidates reconciling the DAMA annual modulation signal with the
results of other null experiments. We show that Singlet Fermionic Dark Matter
can be such a dark matter candidate, simultaneously providing the correct
thermal relic density which is consistent with the WMAP data.Comment: 9 pages, 3 figure
New Higgs signals induced by mirror fermion mixing effects
We study the conditions under which flavor violation arises in scalar-fermion
interactions, as a result of the mixing phenomena between the standard model
and exotic fermions. Phenomenological consequences are discussed within the
specific context of a left-right model where these additional fermions have
mirror properties under the new SU(2)_R gauge group.
Bounds on the parameters of the model are obtained from LFV processes; these
results are then used to study the LFV Higgs decays (H --> tau l_j, l_j = e,
mu), which reach branching ratios that could be detected at future colliders.Comment: 12 pages, 2 figures, ReVTex4, graphicx, to be published in Phys. Rev.
Controlling dipole-dipole frequency shifts in a lattice-based optical atomic clock
Motivated by the ideas of using cold alkaline earth atoms trapped in an
optical lattice for realization of optical atomic clocks, we investigate
theoretically the perturbative effects of atom-atom interactions on a clock
transition frequency. These interactions are mediated by the dipole fields
associated with the optically excited atoms. We predict resonance-like features
in the frequency shifts when constructive interference among atomic dipoles
occur. We theoretically demonstrate that by fine-tuning the coherent
dipole-dipole couplings in appropriately designed lattice geometries, the
undesirable frequency shifts can be greatly suppressed.Comment: 14 pages, 4 figure
A "Littlest Higgs" Model with Custodial SU(2) Symmetry
In this note, a ``littlest higgs'' model is presented which has an
approximate custodial SU(2) symmetry. The model is based on the coset space
. The light pseudo-goldstone bosons of the theory
include a {\it single} higgs doublet below a TeV and a set of three
triplets and an electroweak singlet in the TeV range. All of these scalars
obtain approximately custodial SU(2) preserving vacuum expectation values. This
model addresses a defect in the earlier moose
model, with the only extra complication being an extended top sector. Some of
the precision electroweak observables are computed and do not deviate
appreciably from Standard Model predictions. In an S-T oblique analysis, the
dominant non-Standard Model contributions are the extended top sector and higgs
doublet contributions. In conclusion, a wide range of higgs masses is allowed
in a large region of parameter space consistent with naturalness, where large
higgs masses requires some mild custodial SU(2) violation from the extended top
sector.Comment: 22 pages + 8 figures; JHEP style, added references and extra
discussion on size of T contributions, as well as some other minor
clarifications. Version to appear in JHE
Mass matrix Ansatz and lepton flavor violation in the THDM-III
Predictive Higgs-fermion couplings can be obtained when a specific texture
for the fermion mass matrices is included in the general two-Higgs doublet
model. We derive the form of these couplings in the charged lepton sector using
a Hermitian mass matrix Ansatz with four-texture zeros. The presence of
unconstrained phases in the vertices phi-li-lj modifies the pattern of
flavor-violating Higgs interactions. Bounds on the model parameters are
obtained from present limits on rare lepton flavor violating processes, which
could be extended further by the search for the decay tau -> mu mu mu and mu-e
conversion at future experiments. The signal from Higgs boson decays phi -> tau
mu could be searched at the large hadron collider (LHC), while e-mu transitions
could produce a detectable signal at a future e mu-collider, through the
reaction e mu -> h0 -> tau tau.Comment: 17 pages, 9 figure
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