Gauge singlet extensions of the standard model (SM) scalar sector may help remedy its theoretical and phenomenological shortcomings while solving outstanding problems in cosmology. Depending on symmetries potential, such provide a viable candidate for observed relic density cold dark matter or strong first order electroweak phase transition needed baryogenesis. Using simplest extension SM with one real field, we analyze generic implications singlet-extended Higgs boson phenomenology at Large...

We analyze a simple extension of the standard model (SM) obtained by adding complex singlet to scalar sector (cxSM). show that cxSM can contain one or two viable cold dark matter candidates and conditions on parameters potential yield observed relic density. When contains global $U(1)$ symmetry is both softly spontaneously broken, it candidate ingredients necessary for strong first order electroweak phase transition as needed baryogenesis. also study implications discovery Higgs boson at...

We interpret the new particle at Large Hadron Collider as a CP-even scalar and investigate its electroweak quantum number. Assuming an unbroken custodial invariance suggested by precision measurements, only four possibilities are allowed if decays to pairs of gauge bosons, exemplified dilaton/radion, non-dilatonic singlet scalar, doublet triplet scalars. show that current LHC data already strongly disfavor both dilatonic imposters. On other hand, generic Higgs give excellent fits measured...

Assuming that the positron excess in PAMELA satellite data is a consequence of annihilations cold dark matter, we consider from model-independent perspective if show preference for spin matter. We then perform general analysis into two-body final states to determine what weighted combination channels best describes data.

We adopt a Markov Chain Monte Carlo method to examine various new physics models which can generate the forward-backward asymmetry in top quark pair production observed at Tevatron by CDF Collaboration. study following models: (1) exotic gluon $G^\prime$, (2) extra $Z^\prime$ boson with flavor-conserving interaction, (3) flavor-violating $u$-$t$-$Z^\prime$ (4) $W^\prime$ $d$-$t$-$W^\prime$ and (5) scalars $S$ $S^\pm$ $u$-$t$-$S$ $d$-$t$-$S^\pm$ interactions. After combining measurement of...

We simulate the measurement of triscalar Higgs coupling at LHC(8,14) via pair production h(125 GeV). find that most promising hh final state is bb gamma gamma. account for deviations from its SM value and study effects this on cross-section distributions with cut-based multivariate methods. Our fit to matrix element LHC(14) 3 ab^-1 yields a 40% uncertainty in range 25-80% uncertainties non-SM values.

Extensions of the Minimal Supersymmetric Standard Model (MSSM) with additional singlet scalar fields solve important mu-parameter fine tuning problem MSSM. We compute and compare neutral Higgs boson mass spectra, including one-loop corrections, following MSSM extensions: Next-to-Minimal (NMSSM), nearly-Minimal (nMSSM), U(1)'-extended (UMSSM) by performing scans over model parameters. find that Secluded (sMSSM) is identical to nMSSM if three scalars decouple. The dominant part corrections are...

The CoGeNT and DAMA/LIBRA experiments have found evidence for the spin-independent scattering from nuclei of a light dark matter (DM) particle, 7-12 GeV, which is not excluded by XENON DM experiments. We show that this putative signal can be explained complex scalar singlet extension standard model (CSM), with thermal cosmological density, Higgs sector consistent LEP constraints. make predictions masses, production, decays two mass eigenstates describe how particles discovered at LHC.

Recent observations of high-energy positrons and electrons by the PAMELA ATIC experiments may be an indication annihilation dark matter into leptons not quarks. This leptonic connection was foreseen already some years ago in two different models radiative neutrino mass. We discuss here generic interactions (νη0−lη+)χ lcζ−χc which allow this to happen, where χ and/or χc are fermionic dark-matter candidates. point out particular importance χχ→l+l−γ both positron gamma-ray signals within framework.

Current limits from the Large Hadron Collider exclude a standard model-like Higgs mass above 150 GeV, by placing an upper bound on production rate. We emphasize that, alternatively, limit could be interpreted as lower total decay width of boson. If invisible is same order visible width, heavy boson consistent with null results current searches. propose method to infer using measured h ZZ 4l lineshape, and study effect extraction due reduced signal strength. Assuming product dark matter, we...

We consider the possibility that Higgs can be produced in dark matter annihilations, appearing as a line spectrum of gamma rays at an energy determined by masses WIMP and itself. argue this phenomenon occurs generally models which sector has large couplings to most massive states SM provide simple example inspired Randall-Sundrum vision matter, whose 4d dual corresponds electroweak symmetry-breaking strong dynamics respect global symmetries guarantee stable WIMP. The is Dirac fermion couples...

The discovery at the LHC of a scalar particle with properties that are so far consistent SM Higgs boson is one most important advances in history physics. challenge future collider experiments to determine whether its couplings will show deviations from Higgs, as this would indicate new physics TeV scale, and also probe flavor structure Yukawa couplings. As benchmark alternative we consider generic two doublet model (2HDM) analyze precision which LHC14, an ILC250, 500, 1000 GeV 125 Muon...

We investigate the correlated predictions of singlet extended MSSM models for direct detection and cosmological relic density lightest neutralino. To illustrate general effects singlet, we take heavy sleptons squarks. apply CERN LEP, $(g\ensuremath{-}2{)}_{\ensuremath{\mu}}$, perturbativity constraints. find that WMAP upper bound on cold dark matter limits much parameter space to regions where neutralino can be discovered in recoil experiments. The results next-to-minimal supersymmetric...

We explore the collider signatures of Higgs sectors in singlet extended minimal supersymmetric standard models. find that even with reduced couplings due to mixing, a significant portion parameter spaces have discoverable via traditional decay modes or invisible decays (directly neutralinos through cascade and neutrinos). For illustrative points space we give likelihood discovery. In cases where neither nor can discover Higgs, neutralino sector may provide evidence for

Neutralino annihilations in the Sun to weak boson and top-quark pairs lead high-energy neutrinos that can be detected by IceCube KM3 experiments search for neutralino dark matter. We calculate neutrino signals from real virtual $WW$, $ZZ$, $Zh$, $t\overline{t}$ production decays, accounting spin dependences of matrix elements, which have important influences on energy spectra. take into account propagation including oscillations, matter-resonance, absorption,...

We consider the signals of indirect dark matter detection resulting from a theory two universal extra dimensions compactified on chiral square. Aside continuum emission, which is generic prediction most candidates, we find series prominent annihilation lines (a WIMP forest) that, after convolution with angular resolution current experiments, leads to distinctive (2-bump plus continuum) spectrum, may be visible in near future Fermi Gamma-Ray Space Telescope (formerly known as GLAST).

We evaluate the kinematic distributions in phase space of 4-parton final-state subprocesses produced by double parton scattering, and we contrast these with that originate from conventional single scattering. Our goal is to establish distinct topologies events arise two sources provide a methodology for experimental determination relative magnitude contributions at Large Hadron Collider energies. examine cases detail, $b\overline{b}$ jet-jet 4 jet final states. After full parton-level...

One way to ameliorate the SUSY flavor and $CP$ problems is postulate that scalar masses lie in TeV or beyond regime. For example, focus point (FP) region of minimal supergravity (mSUGRA) model especially compelling heavy can coexist with low fine-tuning while yielding required relic abundance cold dark matter (via a mixed Higgsino-bino neutralino). We examine many characteristics collider events expected arise at CERN LHC models multi-TeV scalars, taking mSUGRA FP as case study. The are...

New experiments designed to discover a weakly interacting dark matter (DM) particle via spin dependent scattering can distinguish models of electroweak symmetry breaking. The plane versus spin-independent DM cross sections is powerful model diagnostic. We detail representative predictions the minimal supergravity (mSUGRA) singlet extended standard and supersymmetric model, new Dirac neutrino, littlest Higgs with $T$-parity (LHT), universal extra dimensions (mUED) models. Of these models,...

We explore the potential for discovery of an exotic color sextet scalar in same-sign top quark pair production early running at LHC. present first phenomenological analysis colliders scalars with full spin correlations included. demonstrate that one can measure mass, polarization, and confirm resonance 1 inverse fb integrated luminosity. The polarization distinguish gauge triplet singlet scalars.

We make a complete catalog of extended Higgs sectors involving $\mathrm{SU}(2{)}_{L}$ doublets and singlets, subject to natural flavor conservation. In each case we present the couplings light neutral $CP$-even state $h$ in terms model parameters, identify which models are distinguishable principle based on this information. also give explicit expressions for parameters exhibit behaviors limit where deviations from standard (SM) small. Finally, discuss prospects differentiation measurements...

An electroweak singlet scalar can couple to pairs of vector bosons through loop-induced dimension five operators. Compared a standard model Higgs boson, the decay widths in diphotons and $Z\ensuremath{\gamma}$ channels are generically enhanced, while decays into massive final states like $WW$ $ZZ$ kinematically disfavored. The overall event rates $\ensuremath{\gamma}\ensuremath{\gamma}$ exceed expectations by orders magnitude. Such may appear as resonant signal channels, even with mass above...