118518956
Bounding the Higgs width at the LHC
We present results for the Standard model description of the four-lepton production, mediated both by Higgs boson production and by other one-loop standard model processes. The description of four-lepton final states in MCFM v6.8 is reviewed, with special reference to the interference effects that can occur for identical species of leptons. We present results both for interference in the $l^+l^- l^- l^+$ and in the $$l^-l^+ \nu_l \bar{\nu}_l$$ final state. Prospects for further improvement in the theoretical description of four lepton production are also reviewed.
18231969
One-loop Higgs plus four gluon amplitudes: full analytic results
We consider one-loop amplitudes of a Higgs boson coupled to gluons in the limit of a large top quark mass. We treat the Higgs as the real part of a complex field ϕ that couples to the self-dual field strengths and compute the one-loop corrections to the ϕ-NMHV amplitude, which contains one gluon of positive helicity whilst the remaining three have negative helicity. We use four-dimensional unitarity to construct the cut-containing contributions and a hybrid of Feynman diagram and recursive based techniques to determine the rational piece. Knowledge of the ϕ-NMHV contribution completes the analytic calculation of the Higgs plus four gluon amplitude. For completeness we also include expressions for the remaining helicity configurations which have been calculated elsewhere. These amplitudes are relevant for Higgs plus jet production via gluon fusion in the limit where the top quark is large compared to all other scales in the problem.
14063809
One-Loop Gluonic Amplitudes from Single Unitarity Cuts
We show that one-loop amplitudes in massless gauge theories can be determined from single cuts. By cutting a single propagator and putting it on-shell, the integrand of an n-point one-loop integral is transformed into an (n+2)-particle tree level amplitude. The single-cut approach described here is complementary to the double or multiple unitarity cut approaches commonly used in the literature. In common with these approaches, if the cut is taken in four dimensions, one finds only the cut-constructible parts of the amplitude, while if the cut is in D = 4−2 dimensions, both rational and cut-constructible parts are obtained. We test our method by reproducing the known results for the fully rational all-plus and mostly-plus QCD amplitudes, A(1)4(1+, 2+, 3+, 4+) and A(1)5(1+, 2+, 3+, 4+, 5+). We also rederive expressions for the scalar loop contribution to the four-gluon MHV amplitude, A4(1, = 0)(−, −, +, +) which has both cut-constructible and rational contributions, and the fully cut-constructible n-gluon MHV amplitude in = 4 Supersymmetric Yang-Mills, A4(1, = 4)(−, −, +, ..., +).
349168
One-loop ϕ-MHV amplitudes using the unitarity bootstrap: the general helicity case
We consider a Higgs boson coupled to gluons via the five-dimensional effective operator HtrGμνGμν. We treat H as the real part of a complex field that couples to the selfdual gluon field strengths and compute the one-loop corrections to the -MHV amplitudes involving , two negative helicity gluons and an arbitrary number of positive helicity gluons. Our results generalise earlier work where the two negative helicity gluons were constrained to be colour adjacent. We use four-dimensional unitarity to construct the cut-containing contributions and the recently developed recursion relations to obtain the rational contribution for an arbitrary number of external gluons. We solve the recursion relations and give explicit results for up to four external gluons. These amplitudes are relevant for Higgs plus jet production via gluon fusion in the limit where the top quark mass is large compared to all other scales in the problem.
116958209
Hadronic productions of a Higgs boson in association with two jets at next-to-leading order
We present an update on the next-to-leading order calculation of the rate for Higgs boson production in association with two jets. Our new calculation incorporates the full analytic result for the one-loop virtual amplitude. Results are presented for the Tevatron, where implications for the Higgs search are sketched, and for the LHC at {radical}s = 7 TeV.
23746592
Front-end electronics and data acquisition system for the MIDAS experiment
The MIDAS (MIcrowave Detection of Air Showers) experiment, a prototype detector to characterize the microwave emission of air showers induced by high energy cosmic rays, has been recently commissioned at the University of Chicago. The receivers, 53 feed horns in the 4GHz band, send the signal to fast power detectors which have logarithmic response to the input RF power. The integrated output signal is continuously digitized in custom 14-bit 20 MHz ADC modules. Data are then processed locally with on-board Field Programmable Gate Arrays (FPGAs) where the trigger logic allows discrimination of events. Local trigger pulses are sent out to a Master Board where a system-wise trigger pulse is generated and sent back to the ADC Modules. After each trigger, a 100 us time stream of data is packed and buffered for readout via the VME back plane. A VME GPS module is also used for precise timing information. Design, specifications of the electronic components, a description of the implemented trigger logic, and preliminary test results will be presented in this contribution.
119118160
A Search for Microwave Emission From Ultra-High Energy Cosmic Rays
We present a search for microwave emission from air showers induced by ultrahigh energy cosmic rays with the microwave detection of air showers experiment. No events were found, ruling out a wide range of power flux and coherence of the putative emission, including those suggested by recent laboratory measurements.
115853080
Coulomb instabilities and multifragment decays