94 research outputs found
The non-compact elliptic genus: mock or modular
We analyze various perspectives on the elliptic genus of non-compact
supersymmetric coset conformal field theories with central charge larger than
three. We calculate the holomorphic part of the elliptic genus via a free field
description of the model, and show that it agrees with algebraic expectations.
The holomorphic part of the elliptic genus is directly related to an
Appell-Lerch sum and behaves anomalously under modular transformation
properties. We analyze the origin of the anomaly by calculating the elliptic
genus through a path integral in a coset conformal field theory. The path
integral codes both the holomorphic part of the elliptic genus, and a
non-holomorphic remainder that finds its origin in the continuous spectrum of
the non-compact model. The remainder term can be shown to agree with a function
that mathematicians introduced to parameterize the difference between mock
theta functions and Jacobi forms. The holomorphic part of the elliptic genus
thus has a path integral completion which renders it non-holomorphic and
modular.Comment: 13 page
Higher Loop Spin Field Correlators in D=4 Superstring Theory
We develop calculational tools to determine higher loop superstring
correlators involving massless fermionic and spin fields in four space time
dimensions. These correlation functions are basic ingredients for the
calculation of loop amplitudes involving both bosons and fermions in D=4
heterotic and superstring theories. To obtain the full amplitudes in Lorentz
covariant form the loop correlators of fermionic and spin fields have to be
expressed in terms of SO(1,3) tensors. This is one of the main achievements in
this work.Comment: 59 pages, 1 figure; v2: final version published in JHE
Yukawa hierarchies at the point of in F-theory
We analyse the structure of Yukawa couplings in local SU(5) F-theory models
with enhancement. In this setting the symmetry is broken down to
SU(5) by a 7-brane configuration described by T-branes, all the Yukawa
couplings are generated in the vicinity of a point and only one family of
quarks and leptons is massive at tree-level. The other two families obtain
their masses when non-perturbative effects are taken into account, being
hierarchically lighter than the third family. However, and contrary to previous
results, we find that this hierarchy of fermion masses is not always
appropriate to reproduce measured data. We find instead that different T-brane
configurations breaking to SU(5) give rise to distinct hierarchical
patterns for the holomorphic Yukawa couplings. Only some of these patterns
allow to fit the observed fermion masses with reasonable local model parameter
values, adding further constraints to the construction of F-theory GUTs. We
consider an model where such appropriate hierarchy is realised and
compute its physical Yukawas, showing that realistic charged fermions masses
can indeed be obtained in this case.Comment: 46 pages + appendices, 5 figures. v2, added references and typos
corrected, version accepted on JHEP. v3, typos correcte
Boundary conditions in Toda theories and minimal models
We show that the disc bulk one-point functions in a sl(n) Toda conformal
field theory have a well-defined limit for the central charge c=n-1, and that
their limiting values can be obtained from a limit of bulk one-point functions
in the W_n minimal models. This comparison leads to a proposal for one-point
functions for twisted boundary conditions in Toda theory.Comment: 33 pages, 1 figure; v2: Minor corrections; v3: version accepted at
JHE
The relationship between the presence of anti-cyclic citrullinated peptide antibodies and clinical phenotype in very early rheumatoid arthritis
<p>Abstract</p> <p>Background</p> <p>Anti-cyclic citrullinated peptide (anti-CCP) antibodies are highly specific for RA, but are not detectable in all RA patients. The aim of this study was to establish whether the clinical phenotypes of anti-CCP positive and negative disease are distinct at the earliest clinically apparent phase of disease.</p> <p>Methods</p> <p>Patients were recruited from the Birmingham early inflammatory arthritis clinic. Participants were included in the current study if they presented within 3 months of symptom onset and fulfilled 1987 ACR criteria for RA at some point during an 18 month follow-up. Data were collected on demographic variables, joint symptoms and tender (n = 68) and swollen (n = 66) joint counts. CRP, ESR, rheumatoid factor and anti-CCP2 status were measured.</p> <p>Results</p> <p>92 patients were included (48 anti-CCP positive). The anti-CCP positive and negative groups were comparable in terms of demographic variables, inflammatory markers, joint counts and 1987 ACR classification criteria, except that more anti-CCP positive patients were rheumatoid factor positive (83.3% vs. 11.4%, p < 0.01). There was no significant difference in the pattern of joint involvement, except for an increased prevalence of knee joint swelling in anti-CCP positive patients (42.9% vs. 22.2%, p = 0.03).</p> <p>Conclusions</p> <p>Patients with and without anti-CCP antibodies present in a similar way, even within three months of clinically apparent disease that eventually develops into RA.</p
Dual Boundary Conditions in 3d SCFT's
We propose matching pairs of half-BPS boundary conditions related by IR
dualities of 3d gauge theories. From these matching pairs we
construct duality interfaces. We test our proposals by anomaly matching and the
computation of supersymmetric indices. Examples include basic abelian
dualities, level-rank dualities, and Aharony dualities.Comment: 99 pages, 3 figures. v2: minor edits, appendix on Weyl-Kac formula
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Supersymmetry: From the Fermi Scale to the Planck Scale
The physics of supersymmetry is reviewed from the perspective of physics at
ever increasing energies. Starting from the minimal supersymmetric extension of
the Standard Model at the electroweak scale, we proceed to higher energies
seeking to understand the origin of the many model parameters. Supersymmetric
grand unification, supergravity, and superstrings are introduced sequentially,
and their contribution to the sought explanations is discussed. Typical
low-energy supersymmetric models are also presented, along with their possible
experimental consequences via direct and indirect processes at high-energy
physics experimental facilities.
Contents
1. Introduction
2. Low-energy Supersymmetry
3. Supersymmetric Grand Unification
4. Supergravity
5. Superstrings
6. Dynamics
7. Experimental Prospects
8. ConclusionsComment: 61 pages, LaTeX, 11 figures (included). To appear in Reports on
Progress in Physic
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