740 research outputs found
The Bethe-Ansatz for N=4 Super Yang-Mills
We derive the one loop mixing matrix for anomalous dimensions in N=4 Super
Yang-Mills. We show that this matrix can be identified with the Hamiltonian of
an integrable SO(6) spin chain with vector sites. We then use the Bethe ansatz
to find a recipe for computing anomalous dimensions for a wide range of
operators. We give exact results for BMN operators with two impurities and
results up to and including first order 1/J corrections for BMN operators with
many impurities. We then use a result of Reshetikhin's to find the exact
one-loop anomalous dimension for an SO(6) singlet in the limit of large bare
dimension. We also show that this last anomalous dimension is proportional to
the square root of the string level in the weak coupling limit.Comment: 35 pages, 3 figures, LaTeX; v2 references added, typos corrected,
\Lambda fixed; v3 expanded discussion of higher loops in conclusion, matches
published versio
New therapeutic perspectives to manage refractory immune checkpoint-related toxicities.
Immune checkpoint inhibitors are reshaping the prognosis of many cancer and are progressively becoming the standard of care in the treatment of many tumour types. Immunotherapy is bringing new hope to patients, but also a whole new spectrum of toxicities for healthcare practitioners to manage. Oncologists and specialists involved in the pluridisciplinary management of patients with cancer are increasingly confronted with the therapeutic challenge of treating patients with severe and refractory immune-related adverse events. In this Personal View, we summarise the therapeutic strategies that have been used to manage such toxicities resulting from immune checkpoint inhibitor treatment. On the basis of current knowledge about their pathogenesis, we discuss the use of new biological and non-biological immunosuppressive drugs to treat severe and steroid refractory immune-related adverse events. Depending on the immune infiltrate type that is predominant, we propose a treatment algorithm for personalised management that goes beyond typical corticosteroid use. We propose a so-called shut-off strategy that aims at inhibiting key inflammatory components involved in the pathophysiological processes of immune-related adverse events, and limits potential adverse effects of drug immunosuppression on tumour response. This approach develops on current guidelines and challenges the step-by-step increase approach to drug immunosuppression
Dynamic Analysis of Unidirectional Pressure Infiltration of Porous Preforms by Pure Metals
Unidirectional pressure infiltration of porous preforms by molten metals is investigated numerically. A phenomenological model to describe fluid flow and transport phenomena during infiltration of fibrous preforms by a metal is formulated. The model describes the dynamics of the infiltration process, the temperature distribution, and solid fraction distribution. The numerical results are compared against classical asymptotic analyses and experimental results. This comparison shows that end effects may become important and render asymptotic results unreliable for realistic samples. Fiber volume fraction and initial temperature appear as the factors most strongly influencing infiltration. Metal superheating affects not only the length of the two-phase zone but also the solid fraction distribution in the two-phase zone. The effect of constant applied pressure, although significant on the infiltration velocity, is almost negligible on the two-phase zone length and on solid fraction distribution. When the initial preform temperature is below the metal melting point, and constant pressure is applied under adiabatic conditions, the flow ceases when sufficient solidification occurs to obstruct it. A comparison with literature experiments proves the model to be an efficient predictive tool in the analysis of infiltration processes for different preform/melt systems
Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV
Results are presented from a search for a W' boson using a dataset
corresponding to 5.0 inverse femtobarns of integrated luminosity collected
during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV.
The W' boson is modeled as a heavy W boson, but different scenarios for the
couplings to fermions are considered, involving both left-handed and
right-handed chiral projections of the fermions, as well as an arbitrary
mixture of the two. The search is performed in the decay channel W' to t b,
leading to a final state signature with a single lepton (e, mu), missing
transverse energy, and jets, at least one of which is tagged as a b-jet. A W'
boson that couples to fermions with the same coupling constant as the W, but to
the right-handed rather than left-handed chiral projections, is excluded for
masses below 1.85 TeV at the 95% confidence level. For the first time using LHC
data, constraints on the W' gauge coupling for a set of left- and right-handed
coupling combinations have been placed. These results represent a significant
improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe
Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV
A search for a Higgs boson decaying into two photons is described. The
analysis is performed using a dataset recorded by the CMS experiment at the LHC
from pp collisions at a centre-of-mass energy of 7 TeV, which corresponds to an
integrated luminosity of 4.8 inverse femtobarns. Limits are set on the cross
section of the standard model Higgs boson decaying to two photons. The expected
exclusion limit at 95% confidence level is between 1.4 and 2.4 times the
standard model cross section in the mass range between 110 and 150 GeV. The
analysis of the data excludes, at 95% confidence level, the standard model
Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The
largest excess of events above the expected standard model background is
observed for a Higgs boson mass hypothesis of 124 GeV with a local significance
of 3.1 sigma. The global significance of observing an excess with a local
significance greater than 3.1 sigma anywhere in the search range 110-150 GeV is
estimated to be 1.8 sigma. More data are required to ascertain the origin of
this excess.Comment: Submitted to Physics Letters
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