49 research outputs found
The helicity amplitudes A and A for the D resonance obtained from the reaction}
The helicity dependence of the reaction
has been measured for the first time in the photon energy range from 550 to 790
MeV. The experiment, performed at the Mainz microtron MAMI, used a
4-detector system, a circularly polarized, tagged photon beam, and a
longitudinally polarized frozen-spin target. These data are predominantly
sensitive to the resonance and are used to determine its
parameters.Comment: 5 pages, 4 figure
First measurement of the Gerasimov-Drell-Hearn integral for Hydrogen from 200 to 800 MeV
A direct measurement of the helicity dependence of the total photoabsorption
cross section on the proton was carried out at MAMI (Mainz) in the energy range
200 < E_gamma < 800 MeV. The experiment used a 4 detection system, a
circularly polarized tagged photon beam and a frozen spin target.
The contributions to the Gerasimov-Drell-Hearn sum rule and to the forward
spin polarizability determined from the data are 226 \pm 5 (stat)\pm
12(sys) \mu b and -187 \pm 8 (stat)\pm 10(sys)10^{-6} fm^4, respectively, for
200 < E_\gamma < 800 MeV.Comment: 6 pages, 3 figures, 3 table
Les Houches 2011: Physics at TeV Colliders New Physics Working Group Report
We present the activities of the "New Physics" working group for the "Physics
at TeV Colliders" workshop (Les Houches, France, 30 May-17 June, 2011). Our
report includes new agreements on formats for interfaces between computational
tools, new tool developments, important signatures for searches at the LHC,
recommendations for presentation of LHC search results, as well as additional
phenomenological studies.Comment: 243 pages, report of the Les Houches 2011 New Physics Group; fix
three figure
Vaccination with murid herpesvirus-4 glycoprotein B reduces viral lytic replication but does not induce detectable virion neutralization
Herpesviruses characteristically disseminate from immune hosts. Therefore in the context of natural infection, antibody neutralizes them poorly. Murid herpesvirus-4 (MuHV-4) provides a tractable model with which to understand gammaherpesvirus neutralization. MuHV-4 virions blocked for cell binding by immune sera remain infectious for IgG-Fc receptor+ myeloid cells, so broadly neutralizing antibodies must target the virion fusion complex â glycoprotein B (gB) or gH/gL. While gB-specific neutralizing antibodies are rare, its domains I+II (gB-N) contain at least one potent neutralization epitope. Here, we tested whether immunization with recombinant gB presenting this epitope could induce neutralizing antibodies in naive mice and protect them against MuHV-4 challenge. Immunizing with the full-length gB extracellular domain induced a strong gB-specific antibody response and reduced MuHV-4 lytic replication but did not induce detectable neutralization. gB-N alone, which more selectively displayed pre-fusion epitopes including neutralization epitopes, also failed to induce neutralizing responses, and while viral lytic replication was again reduced this depended completely on IgG Fc receptors. gB and gB-N also boosted neutralizing responses in only a minority of carrier mice. Therefore, it appears that neutralizing epitopes on gB are intrinsically difficult for the immune response to target
Helicity dependence of the ÎłâpâânÏ+Ï0 reaction in the second resonance region
The helicity dependence of the total cross section for the reaction has been measured for the first time at incident photon energies from 400 to 800 MeV. The measurement was performed with the large acceptance detector DAPHNE at the tagged photon beam facility of the MAMI accelerator in Mainz. This channel is found to be excited predominantly when the photon and proton have a parallel spin orientation, due to the intermediate production of the D13 resonance.
peerReviewe
Medication Analysis for Hospital Patients with Renal Insufficiency: from project development to service establishment
Introducing an interface between WHIZARD and FeynRules
While Monte Carlo event generators like WHIZARD have become indispensable
tools in studying the impact of new physics on collider observables over the
last decades, the implementation of new models in such packages has remained a
rather awkward and error-prone process. Recently, the FeynRules package was
introduced which greatly simplifies this process by providing a single unified
model format from which model implementations for many different Monte Carlo
codes can be derived automatically. In this note, we present an interface which
extends FeynRules to provide this functionality also for the WHIZARD package,
thus making WHIZARD's strengths and performance easily available to model
builders.Comment: 16 pages, 1 figure included, revised versio
Introducing an interface between FeynRules and WHIZARD
While Monte Carlo event generators like WHIZARD have become indispensable
tools in studying the impact of new physics on collider observables over the
last decades, the implementation of new models in such packages has remained a
rather awkward and error-prone process. Recently, the FeynRules package was
introduced which greatly simplifies this process by providing a single unified
model format from which model implementations for many different Monte Carlo
codes can be derived automatically. In this note, we present an interface which
extends FeynRules to provide this functionality also for the WHIZARD package,
thus making WHIZARD's strengths and performance easily available to model
builders.Comment: 16 pages, 1 figure included, revised versio
QCD in the color-flow representation
For many practical purposes, it is convenient to formulate unbroken
non-abelian gauge theories like QCD in a color-flow basis. We present a new
derivation of SU(N) interactions in the color-flow basis by extending the gauge
group to U(N)xU(1)' in such a way that the two U(1) factors cancel each other.
We use the quantum action principles to show the equivalence to the usual basis
to all orders in perturbation theory. We extend the known Feynman rules to
exotic color representations (e.g. sextets) and interactions (e.g.
). We discuss practical applications as they occur in automatic
computation programs.Comment: 37 page