81 research outputs found
Higgs boson decay into four leptons at NLOPS electroweak accuracy
In view of precision studies of the Higgs sector at the Run II of the LHC,
the improvement of the accuracy of the theoretical prediction is becoming a
pressing issue. In this framework, we detail a calculation of the full
Next-to-Leading Order (NLO) electroweak corrections to Higgs boson decay into
four charged leptons, by considering the gold-plated channel H -> Z(*) Z(*) ->
2l 2l', l,l' = e, mu. We match the NLO corrections with a QED Parton Shower
(PS), in order to simulate exclusive multiple photon emission and provide novel
results at NLOPS electroweak accuracy. We compare our NLO predictions to those
of the program Prophecy4f and present NLOPS phenomenological results relevant
for Higgs physics studies, with particular attention to precision measurements
of the Higgs boson mass, spin-parity assignment and tests of the Standard
Model. Our calculation is implemented in a new code, Hto4l, which can be easily
interfaced to any generator describing Higgs boson production. As an example,
we provide illustrative results for Higgs production and decay in the process
gg -> H -> 4l using POWHEG with NLOPS accuracy in the production mode.Comment: 27 pages, 2 tables, 9 figures. New numerical results and plots for
dressed leptons. Conclusions unchanged. Version to appear in JHE
Precision Measurement of the W-Boson Mass: Theoretical Contributions and Uncertainties
We perform a comprehensive analysis of electroweak, QED and mixed
QCD-electroweak corrections underlying the precise measurement of the W-boson
mass M_W at hadron colliders. By applying a template fitting technique, we
detail the impact on M_W of next-to-leading order electroweak and QCD
corrections, multiple photon emission, lepton pair radiation and factorizable
QCD-electroweak contributions. As a by-product, we provide an up-to-date
estimate of the main theoretical uncertainties of perturbative nature. Our
results can serve as a guideline for the assessment of the theoretical
systematics at the Tevatron and LHC and allow a more robust precision
measurement of the W-boson mass at hadron colliders.Comment: 51 pages, 10 figures and 16 tables. Minor corrections: new citations
and reference to the svn revisions of the POWHEG code. Numerical results and
conclusions unchange
Precision electroweak calculation of the production of a high transverse-momentum lepton pair at hadron colliders
We present a detailed study of the production of a high transverse-momentum
lepton pair at hadron colliders, which includes the exact O(alpha) electroweak
corrections properly matched with leading logarithmic effects due to multiple
photon emission, as required by the experiments at the Fermilab Tevatron and
the CERN LHC. Numerical results for the relevant observables of single Z-boson
production at hadron colliders are presented. The impact of the radiative
corrections is discussed in detail. The presence in the proton of a photon
density is considered and the effects of the photon-induced partonic
subprocesses are analyzed. The calculation has been implemented in the new
version of the event generator HORACE, which is available for precision
simulations of the neutral and charged current Drell-Yan processes.Comment: October 2007, 22p
Strategies for successful vaccination against hepatocellular carcinoma.
Current therapies against hepatocellular carcinoma (HCC) are not curative in the majority of patients. In the past, immunotherapy approaches aimed to non-specifically stimulate immune response were quite ineffective. New treatments based on stimulation of specific anti-tumor immune response are currently proposed and appear more promising. Tumor-specific antigens identified in HCC demonstrated immunogenicity both in preclinical and clinical trials. Effectiveness in animal studies raised interest in the clinical applicability of non-specific adoptive immunotherapy that prevented disease recurrence after tumor resection. Dendritic cell (DC)-based tumor vaccines achieved encouraging results, and cellular vaccines based on DCs have already entered clinical trials. Preventive and therapeutic DNA vaccination have been proposed, all based on tumor-associated antigens (TAAs), either modified or not, an example being alpha-fetoprotein (AFP). The concomitant expression of co-stimulatory molecules and cytokines was used to increase tumor immunogenicity. Syngeneic or nude mice models indicated that immunotherapy for HCC could stimulate an anti-tumor T-cell response leading to clinical benefit devoid of significant toxicity. The use of DNA-based vaccination raises exciting possibilities in preventing HCC in high-risk individuals such as those with cirrhosis. Novel immunotherapy strategies may contribute in the future to prevention and treatment of HCC
Multiple photon corrections to the neutral-current Drell-Yan process
Precision studies of single W and Z production processes at hadron colliders
require progress in the calculation of electroweak radiative corrections. To
this end, higher-order QED corrections to the neutral-current Drell-Yan
process, due to multiple photon radiation in Z leptonic decays, are calculated.
Particular attention is paid to the effects induced by such corrections on the
experimental observables which are relevant for high-precision measurements of
the W-boson mass at the Tevatron Run II and the LHC. The calculation is
implemented in the Monte Carlo event generator HORACE, which is available for
data analysis.Comment: 16 pages, 4 figures, 3 tables, JHEP3 styl
Electroweak corrections to as a luminosity process at FCC-ee
We consider large-angle two photon production in annihilation as a
possible process to monitor the luminosity of a future circular
collider (FCC-ee). We review and assess the status of the theoretical accuracy
by performing a detailed phenomenological study of next-to-leading order
electroweak corrections and leading logarithmic QED contributions due to
multiple photon radiation. We also estimate the impact of photonic and
fermion-loop corrections at next-to-next-to-leading order and the uncertainty
induced by the hadronic contribution to the vacuum polarization. Possible
perspectives to address the target theoretical accuracy are briefly discussed.Comment: 13 pages, 3 figures, 3 tables. Extended version, with theoretical
details and further numerical results, of the contribution to the workshop
proceedings arXiv:1905.05078 by the same authors. v2: minor text
modification, one reference adde
Muon-electron scattering at NLO
We consider the process of muon-electron elastic scattering, which has been
proposed as an ideal framework to measure the running of the electromagnetic
coupling constant at space-like momenta and determine the leading-order
hadronic contribution to the muon (MUonE experiment). We compute the
next-to-leading (NLO) contributions due to QED and purely weak corrections and
implement them into a fully differential Monte Carlo event generator, which is
available for first experimental studies. We show representative
phenomenological results of interest for the MUonE experiment and examine in
detail the impact of the various sources of radiative corrections under
different selection criteria, in order to study the dependence of the NLO
contributions on the applied cuts. The study represents the first step towards
the realisation of a high-precision Monte Carlo code necessary for data
analysis.Comment: 25 pages, 2 tables, 14 figures. Minor typos corrected, reference 31
updated. Version matching publication on JHE
Matching perturbative and Parton Shower corrections to Bhabha process at flavour factories
We report on a high-precision calculation of the Bhabha process in Quantum
Electrodynamics, of interest for precise luminosity determination of
electron-positron colliders involved in R measurements in the region of
hadronic resonances. The calculation is based on the matching of exact
next-to-leading order corrections with a Parton Shower algorithm. The accuracy
of the approach is demonstrated in comparison with existing independent
calculations and through a detailed analysis of the main components of
theoretical uncertainty, including two-loop corrections, hadronic vacuum
polarization and light pair contributions. The calculation is implemented in an
improved version of the event generator BABAYAGA with a theoretical accuracy of
the order of 0.1%. The generator is now available for high-precision
simulations of the Bhabha process at flavour factories.Comment: 34 pages, 8 figures, uses elsart.cls. Version to appear on Nuclear
Physics
Expression of high- and low-affinity epidermal growth factor receptors in human hepatoma cell lines
AbstractData are presented from a comparative research on expression of epidermal growth factor (EGF) receptors and response to EGF of six independently established cell lines derived from human hepatoma. These lines differ in terms of the degree of differentiation, presence of hepatitis B virus (HBV) DNA copies in integrated form and expression of HBV genes. Our results indicate differential expression of membrane EGF receptors and differential response to EGF under serum- and hormone-free culture conditions. Furthermore, a significant difference in affinity could be detected between EGF receptors of the two highly dedifferentiated cell lines (HA22T/VGH and Li7A) whose replication is inhibited by EGF concentrations capable of stimulating more differentiated phenotypes
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