Working Paper 35: Carbon Cycling in Southwestern Forests: Reservoirs, Fluxes, and the Effects of Fire and Management

Forests play a key role in regulating the carbon cycle of the Earth system. Understanding carbon storage in forest ecosystems has become increasingly important as human activities release more carbon dioxide (CO2) into the Earth’s atmosphere. The intent of this working paper is to explain the basics of the carbon cycle detailing how much carbon moves through vegetation, water, and soils over time. The paper also summarizes where current science suggests that carbon cycling patterns are most likely to change in the coming years to decades, and how management can influence these changes. Water (H2O) and atmospheric gases, particularly carbon dioxide, interact with living things, soils and rock to regulate natural habitats and sustain ecosystems (NRC 2001). The capacity of landscapes to transfer (“flux”) and store (“sequester”) elemental carbon has a direct effect on atmospheric concentrations of CO2 with further feedbacks on the water and nitrogen cycles. In the literature, carbon contained in vegetation and soils is typically referred to as “reservoirs” or “pools” (Post et al. 1990, Schimel 1995, Cole et al. 2007)

Fact Sheet: Carbon Cycling in Southwestern Forests: Reservoirs, Fluxes, and the Effects of Fire and Management

Forest death from extreme drought and wildfires are reducing regional carbon reservoirs and overall forest sequestration capacity. At the same time, land use practices and development have increased the vulnerabil- ity of some forests during extreme droughts. The intent of this fact sheet is to explain the basics of the car- bon cycle in southwestern forests. It also summarizes how carbon cycling patterns are most likely to change in the coming years to decades in the Southwest

Higgs pair production in the MSSM with explicit CP violation

In the minimal supersymmetric standard model with explicit CP violation, associated production of the lightest Higgs boson with heavier ones is analyzed. Due to explicit CP violation, the Higgs bosons are no longer CP eigenstates so that both of the heavy Higgs bosons contribute to the process. While the radiative corrections in the Higgs sector turn out to be quite important, the vertex radiative corrections remain small as in the CP conserving theory.Comment: 5 pp, 5 figs, Talk at Valencia 99, Valencia, Spain, May 3-8, 199

Using tourism free-choice learning experiences to promote environmentally sustainable behaviour: The role of post-visit ‘action resources’

This paper argues the need for the providers of ecotourism and other free‐choice environmental learning experiences to promote the adoption of environmentally sustainable actions beyond their own sites, when visitors return to their home environments. Previous research indicates that although visitors often leave such experiences with a heightened awareness of conservation issues and intentions to adopt environmentally responsible behaviours, only a minority translate these intentions into real actions. Building on research and theory in relation to visitor experiences in free‐choice learning environments, the paper identifies three different stages in the educational process and proposes a strategy for facilitating the translation of visitors' behavioural intentions into the adoption of sustainable actions through the provision of post‐visit action resources

s-Channel Production of MSSM Higgs Bosons at a Muon Collider with Explicit CP Violation

A muon collider with controllable energy resolution and transverse beam polarization provides a powerful probe of the Higgs sector in the minimal supersymmetric standard model with explicit CP violation, through s-channel production of Higgs bosons. The production rates and the CP-even and CP-odd transverse-polarization asymmetries are complementary in diagnosing CP violation in the Higgs sector.Comment: 12 pages, 5 figures. Some statements for clarity and references added. To appear in Phys. Rev.

CP Phases in Correlated Production and Decay of Neutralinos in the Minimal Supersymmetric Standard Model

We investigate the associated production of neutralinos $e^+e^-\to\tilde{\chi}^0_1\tilde{\chi}^0_2$ accompanied by the neutralino leptonic decay $\tilde{\chi}^0_2\to\tilde{\chi}^0_1 \ell^+\ell^-$, taking into account initial beam polarization and production-decay spin correlations in the minimal supersymmetric standard model with general CP phases but without generational mixing in the slepton sector. The stringent constraints from the electron EDM on the CP phases are also included in the discussion. Initial beam polarizations lead to three CP--even distributions and one CP--odd distribution, which can be studied independently of the details of the neutralino decays. We find that the production cross section and the branching fractions of the leptonic neutralino decays are very sensitive to the CP phases. In addition, the production--decay spin correlations lead to several CP--even observables such as lepton invariant mass distribution, and lepton angular distribution, and one interesting T--odd (CP--odd) triple product of the initial electron momentum and two final lepton momenta, the size of which might be large enough to be measured at the high--luminosity future electron--positron collider or can play a complementary role in constraining the CP phases with the EDM constraints.Comment: Revtex, 37 pages, 12 eps figure

Probing MSSM Higgs Sector with Explicit CP Violation at a Photon Linear Collider

The CP properties of Higgs bosons can be probed through their s-channel resonance productions via photon-photon collisions by use of circularly and/or linearly polarized backscattered laser photons at a TeV-scale linear e^+ e^- collider. Exploiting this powerful tool, we investigate in detail the Higgs sector of the minimal supersymmetric Standard Model with explicit CP violation.Comment: 18 pages, 5 figures. Some comments added and typos corrected. To appear in Phys. Rev.

Additional phases induced by the supersymmetric CP phases

The explicit CP violation in the MSSM radiatively induces a finite unremovable alignment between the Higgs doublets. This additinal phase can be as large as the original CP phases in certain portions of the MSSM parameter space. Considering the specific case of the charginos, this additional phase is shown to induce a conceivable amount of CP violation near the would--be CP conserving points. Moreover, the CP violation in the absence of this phase is smaller than the one in the presence of it, and the former can never compete with the latter, however large $\tan\beta$ is.Comment: 29 pp, 15 fig

Instantons and the endpoint of the lepton energy spectrum in charmless semileptonic BB decays

A recent calculation by Chay and Rey has shown that instantons may make a significant contribution to the lepton energy spectrum near its endpoint. Using an ansatz borrowed from the study of high energy baryon number violating processes, we investigate whether these corrections could spoil the relation between the nonperturbative contributions to this spectrum and to the photon energy spectrum in radiative $B$ decays. We find, in general, that this universality may well fail unless the spectrum is smeared over a region which is considerably larger than had previously been thought necessary. This result affects the possibility of performing a reliable measurement of $V_{ub}$ using inclusive decays.Comment: Slightly revised version, to appear in Phys. Rev. D. A few additional comments have been added on the approximations which are used. 13 pages, 2 embedded uuencoded figures, uses REVTe

Effects of the supersymmetric phases on the neutral Higgs sector

By using the effective potential approximation and taking into account the dominant top quark and scalar top quark loops, radiative corrections to MSSM Higgs potential are computed in the presence of the supersymmetric CP-violating phases. It is found that, the lightest Higgs scalar remains essentially CP-even as in the CP-invariant theory whereas the other two scalars are heavy and do not have definite CP properties. The supersymmetric CP-violating phases are shown to modify significantly the decay rates of the scalars to fermion pairs.Comment: 24 pp, 8 figs, 2 tables, typos and errors correcte