Quartic Anomalous Couplings in γγ\gamma\gamma Colliders

We study the constraints on the vertices $W^+W^- Z\gamma$, $W^+W^-\gamma\gamma$, and $ZZ\gamma\gamma$ that can be obtained from triple-gauge-boson production at the next generation of linear $e^+e^-$ colliders operating in the $\gamma\gamma$ mode. We analyze the processes $\gamma\gamma \to W^+W^-V$ ($V=Z$, or $\gamma$) and show that these reactions increase the potential of $e^+e^-$ machines to search for anomalous four-gauge-boson interactions.Comment: 15 pages, Latex file using ReVteX, 4 uufiled figures include

Probing Anomalous Quartic Couplings in e-gamma and gamma-gamma Colliders

We analyze the potential of the e+e- Linear Colliders, operating in the e-gamma and gamma-gamma modes, to probe anomalous quartic vector--boson interactions through the multiple production of W's and Z's. We examine all $SU(2)_L \otimes U(1)_Y$ chiral operators of order p^4 that lead to new four--gauge--boson interactions but do not alter trilinear vertices. We show that the e-gamma and gamma-gamma modes are able not only to establish the existence of a strongly interacting symmetry breaking sector but also to probe for anomalous quartic couplings of the order of 10^{-2} at 90% CL. Moreover, the information gathered in the e-gamma mode can be used to reduced the ambiguities of the e+e- mode.Comment: Revtex, 18 pages, 6 figure

Triple Electroweak Gauge-Boson Production at Fermilab Tevatron Energies

We calculate the three gauge-boson production in the Standard Model at Fermilab Tevatron energies. At $\sqrt s=2$ TeV in $p\bar p$ collisions, the cross sections for the triple gauge-boson production are typically of order 10 femtobarns (fb). For the pure leptonic final states from the gauge-boson decays and with some minimal cuts on final state photons, the cross sections for $p \bar p \rightarrow W^\pm \gamma\gamma, Z\gamma\gamma$ and $W^+W^- \gamma$ processes are of order a few fb, resulting in a few dozen clean leptonic events for an integrated luminosity of 10 fb$^{-1}$. The pure leptonic modes from other gauge-boson channels give significantly smaller rate. Especially, the trilepton modes from $W^+W^-W^\pm$ and $t \bar t W^\pm \rightarrow W^+W^-W^\pm$ yield a cross section of order 0.1 fb if there is no significant Higgs boson contribution. For a Higgs boson with $m_H^{} \simeq 2M_Z^{}$, the triple massive-gauge-boson production rate could be enhanced by a factor of $4-6$.Comment: RevTeX 3.0; 14 pages plus 7 figures; ps files available via anonymous ftp at ftp://ucdhep.ucdavis.edu/han/vvv/vvv.ps,fig*_vvv.p

Intermediate and heavy Higgs boson physics at a 0.5-TeV e+ e- collider

We explore the potential of a future e^+ e^- collider in the 0.5 TeV center-of-mass energy range to detect intermediate or heavy Higgs bosons in the Standard Model. We first briefly assess the production cross sections and update the decay branching fractions for a Higgs boson of intermediate mass, with M_Z < m_H < 2M_W. We then study in detail the possibility of detecting a heavy Higgs boson, with m_H > 2M_W, through the production of pairs of weak bosons. We quantitatively analyze the sensitivity of the process e^+ e^- --> nu nubar W^+ W^- (ZZ) to the presence of a heavy Higgs-boson resonance in the Standard Model. We compare this signal to various backgrounds and to the smaller signal from e^+ e^- --> ZH --> mu^+ mu^- W^+ W^- (ZZ), assuming the weak-boson pairs to be detected and measured in their dominant hadronic decay modes W^+ W^- (ZZ) --> 4jets. A related Higgs-boson signal in 6-jet final states is also estimated. We show how the main backgrounds from e^+ e^- W^+ W^- (ZZ), e nu WZ, and t tbar production can be reduced by suitable acceptance cuts. Bremsstrahlung and typical beamstrahlung corrections are calculated. These corrections reduce Higgs-boson production by scattering mechanisms but increase production by annihilation mechanisms; they also smear out some dynamical features such as Jacobian peaks in p_T(H). With all these corrections included, we conclude that it should be possible to detect a heavy Higgs-boson signal in the nu nubar W^+ W^-(ZZ) channels up to mass m_H=350 GeV.Comment: 49 pages, 15 figures (not included

Local studies provide a global perspective of the impacts of climate change on Indigenous Peoples and local communities

Abstract Indigenous Peoples and local communities with nature-dependent livelihoods are disproportionately affected by climate change impacts, but their experience, knowledge and needs receive inadequate attention in climate research and policy. Here, we discuss three key findings of a collaborative research consortium arising from the Local Indicators of Climate Change Impacts project. First, reports of environmental change by Indigenous Peoples and local communities provide holistic, relational, placed-based, culturally-grounded and multi-causal understandings of change, largely focused on processes and elements that are relevant to local livelihoods and cultures. These reports demonstrate that the impacts of climate change intersect with and exacerbate historical effects of socioeconomic and political marginalization. Second, drawing on rich bodies of inter-generational knowledge, Indigenous Peoples and local communities have developed context-specific responses to environmental change grounded in local resources and strategies that often absorb the impacts of multiple drivers of change. Indigenous Peoples and local communities adjust in diverse ways to impacts on their livelihoods, but the adoption of responses often comes at a significant cost due to economic, political, and socio-cultural barriers operating at societal, community, household, and individual levels. Finally, divergent understandings of change challenge generalizations in research examining the human dimensions of climate change. Evidence from Indigenous and local knowledge systems is context-dependent and not always aligned with scientific evidence. Exploring divergent understandings of the concept of change derived from different knowledge systems can yield new insights which may help prioritize research and policy actions to address local needs and priorities.Science highlights →Place-based communities provide holistic, culturally-grounded, and multi-causal reports of change. →Place-based communities rely on local means to adapt to change, but implementing responses incurs costs. →Local reports of change reveal grounded needs and interests that could guide research and policy action. Policy and practice recommendations →Recognize Indigenous Peoples and local communities as legitimate custodians of climate change knowledge. →Uphold Indigenous Peoples’ rights to participate in climate change decision-making. →Adjust research to ensure that funding, timing and data ownership align with local needs and interests