248 research outputs found
Perturbative unitarity of Lee-Wick quantum field theory
We study the perturbative unitarity of the Lee-Wick models, formulated as
nonanalytically Wick rotated Euclidean theories. The complex energy plane is
divided into disconnected regions and the values of a loop integral in the
various regions are related to one another by a nonanalytic procedure. We show
that the one-loop diagrams satisfy the expected, unitary cutting equations in
each region: only the physical degrees of freedom propagate through the cuts.
The goal can be achieved by working in suitable subsets of each region and
proving that the cutting equations can be analytically continued as a whole. We
make explicit calculations in the cases of the bubble and triangle diagrams and
address the generality of our approach. We also show that the same
higher-derivative models violate unitarity if they are formulated directly in
Minkowski spacetime.Comment: 30 pages, 15 figures; v2: more details and comments on generality of
approach; v3: minor changes, PR
A new formulation of Lee-Wick quantum field theory
The Lee-Wick models are higher-derivative theories that are claimed to be
unitary thanks to a peculiar cancelation mechanism. In this paper, we provide a
new formulation of the models, to clarify several aspects that have remained
quite mysterious, so far. Specifically, we define them as nonanalytically Wick
rotated Euclidean theories. The complex energy plane is divided into
disconnected regions, which can be related to one another by a well-defined,
albeit nonanalytic procedure. Working in a generic Lorentz frame, the models
are intrinsically equipped with the right recipe to treat the pinchings of the
Lee-Wick poles, with no need of external ad hoc prescriptions. We describe
these features in detail by calculating the one-loop bubble diagram and
explaining how the key properties generalize to more complicated diagrams. The
physical results of our formulation are different from those of the previous
ones. The unusual behaviors of the physical amplitudes lead to interesting
phenomenological predictions.Comment: 27 pages, 17 figures; v2: details about Lorentz invariance above LW
thresholds; v3: minor changes, JHE
Quantum Gravity, Fakeons And Microcausality
We investigate the properties of fakeons in quantum gravity at one loop. The
theory is described by a graviton multiplet, which contains the fluctuation
of the metric, a massive scalar and the spin-2 fakeon
. The fields and are introduced
explicitly at the level of the Lagrangian by means of standard procedures. We
consider two options, where is quantized as a physical particle or a
fakeon, and compute the absorptive part of the self-energy of the graviton
multiplet. The width of , which is negative, shows that the
theory predicts the violation of causality at energies larger than the fakeon
mass. We address this issue and compare the results with those of the Stelle
theory, where is a ghost instead of a fakeon.Comment: 24 pages, 2 figures; v2: minor changes, JHE
Anti epidermal growth factor receptor therapy in small bowel adenocarcinoma
Rationale:Small bowel adenocarcinoma (SBA) is an uncommon gastrointestinal cancer, thus limited data about treatment for advanced disease are available. The lack of specific guidelines has justified the use of therapeutic protocols usually applied in advanced colorectal cancer. Few and preliminary data have suggested possible clinical benefit from the use of target therapy such as bevacizumab and cetuximab.Patient concerns:We present the case of a young woman who was admitted to the emergency department for acute abdominal pain, nausea, and vomiting related to a jejunal stenosis.Diagnoses:An enteroscopy with jejunal biopsy showed poorly differentiated cancerous cells suggestive for primary intestinal cancer. There were no signs of metastatic disease at radiological evaluation. A jejunal resection was subsequently carried out and the diagnosis of mucinous adenocarcinoma of the jejunum was confirmed.Interventions:The computed tomography scan performed 1 month after surgery showed metastatic disease. Therefore, the patient received combined protocols of chemotherapy and either bevacizumab or the anti-epidermal growth factor receptor (EGFR) panitumumab.Outcomes:A partial response (PR) was achieved with Folfox plus panitumumab and a maintenance therapy with panitumumab is being conducted with a mild toxicity and a progression free survival of 19 months since the beginning of panitumumab.Lessons:This is, to the best of our knowledge, the first report in the literature of a patient with SBA who has benefitted from panitumumab with an overall survival of 83 months
Predictions of quantum gravity in inflationary cosmology: effects of the Weyl-squared term
We derive the predictions of quantum gravity with fakeons on the amplitudes
and spectral indices of the scalar and tensor fluctuations in inflationary
cosmology. The action is plus the Weyl-squared term. The ghost is
eliminated by turning it into a fakeon, that is to say a purely virtual
particle. We work to the next-to-leading order of the expansion around the de
Sitter background. The consistency of the approach puts a lower bound () on the mass of the fakeon with respect to
the mass of the inflaton. The tensor-to-scalar ratio is
predicted within less than an order of magnitude ( to the
leading order in the number of -foldings ). Moreover, the relation
is not affected by the Weyl-squared term. No vector and no
other scalar/tensor degree of freedom is present.Comment: 39 pages, 1 figure; v2: minor changes, JHE
Synthesis, Structural Elucidation, and Biological Evaluation of NSC12, an Orally Available Fibroblast Growth Factor (FGF) Ligand Trap for the Treatment of FGF-Dependent Lung Tumors
NSC12 is an orally available pan-FGF trap able to inhibit FGF2/FGFR interaction and endowed with promising antitumor activity. It was identified by virtual screening from a NCI small molecule library, but no data were available about its synthesis, stereochemistry, and physicochemical properties. We report here a synthetic route that allowed us to characterize and unambiguously identify the structure of the active compound by a combination of NMR spectroscopy and in silico conformational analysis. The synthetic protocol allowed us to sustain experiments aimed at assessing its therapeutic potential for the treatment of FGF-dependent lung cancers. A crucial step in the synthesis generated a couple of diastereoisomers, with only one able to act as a FGF trap molecule and to inhibit FGF-dependent receptor activation, cell proliferation, and tumor growth when tested in vitro and in vivo on murine and human lung cancer cells
Phenomenology of a Fake Inert Doublet Model
We introduce a new way of modeling the physics beyond the Standard Model by
considering fake, strictly off-shell degrees of freedom: the fakeons. To
demonstrate the approach and exemplify its reach, we re-analyze the
phenomenology of the Inert Doublet Model under the assumption that the second
doublet is a fakeon. Remarkably, the fake doublet avoids the most stringent
-pole constraints regardless of the chosen mass scale, thereby allowing for
the presence of new effects well below the electroweak scale. Furthermore, the
absence of on-shell propagation prevents fakeons from inducing missing energy
signatures in collider experiments. The distinguishing features of the model
appear at the loop level, where fakeons modify the Higgs boson
decay width and the Higgs trilinear coupling. The running of
Standard Model parameters proceeds as in the usual Inert Doublet Model case.
Therefore, the fake doublet can also ensure the stability of the Standard Model
vacuum. Our work shows that fakeons are a valid alternative to the usual tools
of particle physics model building, with the potential to shape a new paradigm,
where the significance of the existing experimental constraints towards new
physics must necessarily be reconsidered.Comment: 12 pages, 7 figures, version accepted by JHE
N=4 Versus N=2 Phases, Hyperk\"Ahler Quotients and the 2D Topological Twist
We consider N=2 and N=4 supersymmetric gauge theories in two-dimensions,
coupled to matter multiplets. In analogy with the N=2 case also in the N=4 case
one can introduce Fayet-Iliopoulos terms.The associated three-parameters have
the meaning of momentum-map levels in a HyperK\"ahler quotient construction.
Differently from the N=2 case, however, the N=4 has a single phase
corresponding to an effective -model. There is no Landau-Ginzburg
phase. The main possible application of our N=4 model is to an effective
Lagrangian construction of a -model on ALE-manifolds. We discuss the A
and B topological twists of these models clarifying some issues not yet
discussed in the literature, in particular the identification of the
topological systems emerging from the twist. Applying our results to the case
of ALE-manifolds we indicate how one can use the topologically twisted theories
to study the K\"ahler class and complex structure deformations of these
gravitational instantons.Comment: plain Latex, 77 pages, SISSA/151/93/E
StrongNet: An International Network to Improve Diagnostics and Access to Treatment for Strongyloidiasis Control
Strongyloidiasis is a disease caused by an infection with a soil-transmitted helminth that affects, according to largely varying estimates, between 30 million and 370 million people worldwide [1,2]. Not officially listed as a neglected tropical disease (NTD), strongyloidiasis stands out as particularly overlooked [3]. Indeed, there is a paucity of research and public health efforts pertaining to strongyloidiasis. Hence, clinical, diagnostic, epidemiologic, treatment, and control aspects are not adequately addressed to allow for an effective management of the disease, both in clinical medicine and in public health programs [4]. The manifold signs and symptoms caused by Strongyloides stercoralis infection, coupled with the helminth’s unique potential to cause lifelong, persistent infection, make strongyloidiasis relevant beyond tropical and subtropical geographic regions, where, however, most of the disease burden is concentrated. Indeed, strongyloidiasis is acquired through contact with contaminated soil, and the infection is, thus, primarily transmitted in areas with poor sanitation, inadequate access to clean water, and lack of hygiene
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