Confirming the LHC Higgs Discovery with WW

We investigate the prospects of observing a neutral Higgs boson decaying into a pair of $W$ bosons (one real and the other virtual), followed by the $W$ decays into $qq' \ell\nu$ or $jj\ell\nu$ at the CERN Large Hadron Collider (LHC). Assuming that the missing transverse energy comes solely from the neutrino in $W$ decay, we can reconstruct the $W$ masses and then the Higgs mass. At the LHC with a center of mass energy ($\sqrt{s}$) of 8 TeV and an integrated luminosity ($L$) of 25 fb$^{-1}$, we can potentially establish a $6\sigma$ signal. A $5\sigma$ discovery of $H \to WW^* \to jj\ell\nu$ for $\sqrt{s} = 14$ TeV can be achieved with $L =$ 6 fb$^{-1}$. The discovery of $H \to WW$ implies that the recently discovered new boson is a CP-even scalar if its spin is zero. In addition, this channel will provide a good opportunity to study the $HWW$ coupling

Dimension-Five Operators in Grand Unified Theories

Extensions of the standard model with low-energy supersymmetry generically allow baryon- and lepton-number violating operators of dimension four and five, yielding rapid proton decay. The dimension-four operators are usually forbidden by matter parity. We investigate to what extent the appearance of dimension-five operators at the Planck scale may be constrained by the different grand-unified gauge groups. Dimension-five operators are suppressed in models based on E_6 and SU(3)_C x SU(3)_L x SU(3)_R, where four matter fields do not form a gauge singlet. An intermediate scale offers the possibility to sufficiently suppress these dimension-five operators.Comment: 4 pages, v3: version to appear in PR

Prospects for Higgs Searches with the Tri-bottom Channel in Unified SUSY Models

We investigate the prospects for the discovery of a neutral Higgs boson produced in association with a $b$ quark, followed by the Higgs decay into a pair of bottom quarks, $pp \to b\phi^0 \to b b\bar{b} +X$, at the CERN Large Hadron Collider (LHC) within the framework of unified supersymmetric models. The Higgs boson $\phi^0$ can be a heavy scalar $H^0$ or a pseudoscalar $A^0$. Furthermore, this direct discovery channel is compared with the indirect Higgs searches in the rare decay $B_s \to \mu^+\mu^-$ at hadron colliders. Promising results are found for the minimal supergravity (mSUGRA) model, the anomaly mediated supersymmetry breaking (AMSB) model, and the gauge mediated supersymmetry breaking (GMSB) model. We find that the indirect search for $B(B_s \to \mu^+\mu^-) \ge 5\times 10^{-9}$ is complementary to the direct search for $b\phi^0 \to bb\bar{b}$ with $\sqrt{s} = 14$ TeV and an integrated luminosity ($L$) of 300 fb$^{-1}$. In the AMSB and GMSB models, $b\phi^0 \to bb\bar{b}$ with $L = 300$ fb$^{-1}$ covers a larger area in the parameter space than $B(B_s \to \mu^+\mu^-) \ge 5\times 10^{-9}$. In addition, we present constraints from $b \to s\gamma$ and muon anomalous dipole moment ($\Delta a_\mu$) on the parameter space.Comment: REVTEX, 23 pages, 4 figure

Searching for Colorons at the Large Hadron Collider

We investigate the prospects for the discovery of massive color-octet vector bosons at the CERN Large Hadron Collider with $\sqrt{s} = 14$ TeV. A phenomenological Lagrangian is adopted to evaluate the cross section of a pair of colored vector bosons (colorons, $\tilde{\rho}$) decaying into four colored scalar resonances (hyper-pions, $\tilde{\pi}$), which then decay into eight gluons. We include the dominant physics background from the production of $8g,7g1q, 6g2q$, and $5g3q$, and determine the masses of $\tilde{\pi}$ and $\tilde{\rho}$ where discovery is possible. For example, we find that a 5$\sigma$ signal can be established for M_{\tilde{\pi}} \alt 495 GeV (M_{\tilde{\rho}} \alt 1650 GeV). More generally we give the reach of this process for a selection of possible cuts and integrated luminosities.Comment: REVTEX, 20 pages, 16 figure

Top-Quark Initiated Processes at High-Energy Hadron Colliders

In hadronic collisions at high energies, the top-quark may be treated as a parton inside a hadron. Top-quark initiated processes become increasingly important since the top-quark luminosity can reach a few percent of the bottom-quark luminosity. In the production of a heavy particle $H$ with mass $m_H > m_t$, treating the top-quark as a parton allows us to resum large logarithms $\log(m_{H}^{2}/m_{t}^{2}$) arising from collinear splitting in the initial state. We quantify the effect of collinear resummation at the 14-TeV LHC and a future 100-TeV hadron collider, focusing on the top-quark open-flavor process $gg\to t\bar t H$ in comparison with $t\bar t \to H$ and $tg\rightarrow tH$ at the leading order (LO) in QCD. We employ top-quark parton distribution functions with appropriate collinear subtraction and power counting. We find that (1) Collinear resummation enhances the inclusive production of a heavy particle with $m_H\approx$ 5 TeV (0.5 TeV) by more than a factor of two compared to the open-flavor process at a 100-TeV (14-TeV) collider; (2) Top-quark mass effects are important for scales $m_H$ near the top-quark threshold, where the cross section is largest. We advocate a modification of the ACOT factorization scheme, dubbed m-ACOT, to consistently treat heavy-quark masses in hadronic collisions; (3) The scale uncertainty of the total cross section in m-ACOT is of about 20 percent at the LO. While a higher-order calculation is indispensable for a precise prediction, the LO cross section is well described by the process $t\bar t\to H$ using an effective factorization scale significantly lower than $m_H$. We illustrate our results by the example of a heavy spin-0 particle. Our main results also apply to the production of particles with spin-1 and 2.Comment: 30 pages, 9 figures, 1 table, matches version published in JHE

Density-dependent and landscape effects upon estuary rearing in Chinook salmon: insights from long-term monitoring in four Puget Sound estuaries

Juvenile Chinook salmon are well known for utilizing estuarine habitats within the tidal delta for rearing during outmigration. Several studies have linked population responses to availability of estuary habitat, and support the hypothesis that estuarine habitats are vital rearing areas for juvenile Chinook salmon. However, these coarse-scale studies provide little insight on how specific estuarine habitats contribute to rearing potential for salmon. We integrate long-term monitoring data from four estuaries of Puget Sound (Nooksack, Skagit, Snohomish, and Nisqually) to examine whether 1) Chinook populations in these rivers are limited by restricted estuary habitat, 2) hatchery releases can influence density dependent relationships in estuaries, 3) highly connected sites support higher densities of salmon, and 4) different habitat types support higher rearing densities of Chinook salmon. Across sampling locations within estuary systems, average annual rearing densities varied over four orders of magnitude. We found strong support for density dependence, habitat type, landscape connectivity, and hatchery release numbers influencing rearing densities, although all factors were not necessarily as important within each system, and effects of habitat type were particularly variable. Further work using bioenergetics models suggest that habitat-dependent variation in temperature can strongly influence growth in different systems, and that multiple habitats are likely important to provide suitable habitat for extended estuary rearing. These analyses are useful for determining the relative contribution of connectivity, cohort population size, and local habitat conditions for growth potential of Chinook salmon using estuarine habitats at early life stages, and shed light on likely impacts of climate change upon rearing conditions

Discovering the Higgs Bosons of Minimal Supersymmetry with Bottom Quarks

We investigate the prospects for the discovery of a neutral Higgs boson produced with one bottom quark followed by Higgs decay into a pair of bottom quarks at the CERN Large Hadron Collider (LHC) and the Fermilab Tevatron Collider. We work within the framework of the minimal supersymmetric standard model. The dominant physics background is calculated with realistic acceptance cuts and efficiencies including the production of $bb\bar{b}$, $\bar{b}b\bar{b}$, $jb\bar{b}$ ($j = g, q, \bar{q}$; $q = u, d, s, c$), $t\bar{t} \to b\bar{b}jj\ell\nu$, and $t\bar{t} \to b\bar{b}jjjj$. Promising results are found for the CP-odd pseudoscalar ($A^0$) and the heavier CP-even scalar ($H^0$) Higgs bosons with masses up to 800 GeV for the LHC with an integrated luminosity ($L$) of 30 fb$^{-1}$ and up to 1 TeV for $L =$ 300 fb$^{-1}$.Comment: Revised version to appear in Physics Letters

Association of Amygdala Development with Different Forms of Anxiety in Autism Spectrum Disorder

Background: The amygdala is widely implicated in both anxiety and autism spectrum disorder. However, no studies have investigated the relationship between co-occurring anxiety and longitudinal amygdala development in autism. Here, the authors characterize amygdala development across childhood in autistic children with and without traditional DSM forms of anxiety and anxieties distinctly related to autism. Methods: Longitudinal MRI scans were acquired at up to four timepoints for 71 autistic and 55 typically developing (TD) children (∼2.5-12 years, 411 timepoints). Traditional DSM anxiety and anxieties distinctly related to autism were assessed at study Time 4 (∼8-12 years) using a diagnostic interview tailored to autism: The Anxiety Disorders Interview Schedule-IV with the Autism Spectrum Addendum. Mixed effects models were used to test group differences at study Time 1 (3.18 years), Time 4 (11.36 years), and developmental differences (age-by-group interactions) in right and left amygdala volume between autistic children with and without DSM or autism distinct anxieties, and TD. Results: Autistic children with DSM anxiety had significantly larger right amygdala volumes compared to TD at both study Time 1 (5.10% increase) and Time 4 (6.11% increase). Autistic children with autism distinct anxieties had significantly slower right amygdala growth compared to TD, autism-no anxiety, and autism-DSM anxiety groups and smaller right amygdala volumes at Time 4 compared to the autism-no anxiety (-8.13% decrease) and autism-DSM anxiety (-12.05% decrease) groups. Conclusions: Disparate amygdala volumes and developmental trajectories between DSM and autism distinct forms of anxiety suggest different biological underpinnings for these common, co-occurring conditions in autism