16 research outputs found
Determining the Higgs Boson Self Coupling at Hadron Colliders
Inclusive Standard Model Higgs boson pair production at hadron colliders has
the capability to determine the Higgs boson self-coupling, lambda. We present a
detailed analysis of the gg\to HH\to (W^+W^-)(W^+W^-)\to
(jjl^\pm\nu)(jj{l'}^\pm\nu) and gg\to HH\to (W^+W^-)(W^+W^-)\to
(jjl^\pm\nu)({l'}^\pm\nu {l''}^\mp\nu) (l, {l'}, {l''}=e, \mu) signal channels,
and the relevant background processes, for the CERN Large Hadron Collider, and
a future Very Large Hadron Collider operating at a center-of-mass energy of 200
TeV. We also derive quantitative sensitivity limits for lambda. We find that it
should be possible at the LHC with design luminosity to establish that the
Standard Model Higgs boson has a non-zero self-coupling and that lambda /
lambda_{SM} can be restricted to a range of 0-3.8 at 95% confidence level (CL)
if its mass is between 150 and 200 GeV. At a 200 TeV collider with an
integrated luminosity of 300 fb^{-1}, lambda can be determined with an accuracy
of 8 - 25% at 95% CL in the same mass range.Comment: 28 pages, Revtex3, 9 figures, 3 table
Examining the Higgs boson potential at lepton and hadron colliders: a comparative analysis
We investigate inclusive Standard Model Higgs boson pair production at lepton
and hadron colliders for Higgs boson masses in the range 120 GeV < m_H < 200
GeV. For m_H < 140 GeV we find that hadron colliders have a very limited
capability to determine the Higgs boson self-coupling, \lambda, due to an
overwhelming background. We also find that, in this mass range, supersymmetric
Higgs boson pairs may be observable at the LHC, but a measurement of the self
coupling will not be possible. For m_H > 140 GeV we examine ZHH and HH nu
bar-nu production at a future e+e- linear collider with center of mass energy
in the range of sqrt{s}=0.5 - 1 TeV, and find that this is likely to be equally
difficult. Combining our results with those of previous literature, which has
demonstrated the capability of hadron and lepton machines to determine \lambda
in either the high or the low mass regions, we establish a very strong
complementarity of these machines.Comment: Revtex, 25 pages, 2 tables, 10 figure
Ten millennia of hepatitis B virus evolution
Hepatitis B virus (HBV) has been infecting humans for millennia and remains a global health problem, but its past diversity and dispersal routes are largely unknown. We generated HBV genomic data from 137 Eurasians and Native Americans dated between similar to 10,500 and similar to 400 years ago. We date the most recent common ancestor of all HBV lineages to between similar to 20,000 and 12,000 years ago, with the virus present in European and South American hunter-gatherers during the early Holocene. After the European Neolithic transition, Mesolithic HBV strains were replaced by a lineage likely disseminated by early farmers that prevailed throughout western Eurasia for similar to 4000 years, declining around the end of the 2nd millennium BCE. The only remnant of this prehistoric HBV diversity is the rare genotype G, which appears to have reemerged during the HIV pandemic.Molecular Technology and Informatics for Personalised Medicine and Healt