Weak Scale Supersymmetry Emergent from the String Landscape.

Superstring flux compactifications can stabilize all moduli while leading to an enormous number of vacua solutions, each leading to different 4-d laws of physics. While the string landscape provides at present the only plausible explanation for the size of the cosmological constant, it may also predict the form of weak scale supersymmetry which is expected to emerge. Rather general arguments suggest a power-law draw to large soft terms, but these are subject to an anthropic selection of a not-too-large value for the weak scale.

New physics in resonant production of Higgs boson pairs.

We advocate a search for an extended scalar sector at the LHC via hh production, where h is the 125 GeV Higgs boson. A resonance feature in the hh invariant mass is a smoking gun of an s-channel heavy Higgs resonance, H. With one h decaying to two photons and the other decaying to b quarks, the resonant signal may be discoverable above the hh continuum background for M(H)<1  TeV.

Same-sign diboson signature from supersymmetry models with light Higgsinos at the LHC.

In supersymmetric models with light Higgsinos (which are motivated by electroweak naturalness arguments), the direct production of Higgsino pairs may be difficult to search for at the LHC due to the low visible energy release from their decays. However, the wino pair production reaction W2(±)Z4→(W(±)Z1,2)+(W(±)W1(∓)) also occurs at substantial rates and leads to final states including equally opposite-sign and same-sign diboson production. We propose a novel search channel for LHC14 based on the same-sign diboson plus missing ET final state which contains only modest jet activity.

Radiative natural supersymmetry with a 125 GeV Higgs boson.

It has been argued that requiring low electroweak fine-tuning (EWFT) along with a (partial) decoupling solution to the supersymmetry (SUSY) flavor and CP problems leads to a sparticle mass spectra characterized by light Higgsinos at 100-300 GeV, sub-TeV third generation scalars, gluinos at a few TeV, and multi-TeV first or second generation scalars (natural SUSY). We show that by starting with multi-TeV first or second and third generation scalars and trilinear soft breaking terms, the natural SUSY spectrum can be generated radiatively via renormalization group running effects. Using the complete 1-loop effective potential to calculate EWFT, significantly heavier third generation squarks can be allowed even with low EWFT.

Total width of 125 GeV Higgs boson.

By using the LHC and Tevatron measurements of the cross sections to various decay channels relative to the standard model Higgs boson, the total width of the putative 125 GeV Higgs boson is determined as 6.1(-2.9)(+7.

Neutrino mass hierarchy and octant determination with atmospheric neutrinos.

The recent discovery by the Daya-Bay and RENO experiments, that θ(13) is nonzero and relatively large, significantly impacts existing experiments and the planning of future facilities. In many scenarios, the nonzero value of θ(13) implies that θ(23) is likely to be different from π/4. Additionally, large detectors will be sensitive to matter effects on the oscillations of atmospheric neutrinos, making it possible to determine the neutrino mass hierarchy and the octant of θ(23).

Searching for stoponium along with the Higgs boson.

Stoponium, a bound state of the top squark and its antiparticle in a supersymmetric model, may be found in the ongoing Higgs searches at the LHC. Its WW and ZZ detection ratios relative to the standard model Higgs boson can be more than unity from the WW* threshold to the two Higgs threshold. The γγ channel is equally promising.

Constraint on parity-violating muonic forces.

Using the nonobservance of missing mass events in the leptonic kaon decay K→μX, we place a strong constraint on exotic parity-violating gauge interactions of the right-handed muon. By way of illustration, we apply it to an explanation of the proton size anomaly that invokes such a new force; scenarios in which the gauge boson decays invisibly or is long lived are constrained.

Differentiating the Higgs boson from the dilaton and radion at Hadron colliders.

A number of candidate theories beyond the standard model (SM) predict new scalar bosons below the TeV region. Among these, the radion, which is predicted in the Randall-Sundrum model, and the dilaton, which is predicted by the walking technicolor theory, have very similar couplings to those of the SM Higgs boson, and it is very difficult to differentiate these three spin-0 particles in the expected signals of the Higgs boson at the LHC and Tevatron. We demonstrate that the observation of the ratio σ(γγ)/σ(WW) gives a simple and decisive way to differentiate these, independent of the values of model parameters, the vacuum expectation values of the radion, and dilaton fields.

Proton size anomaly.

A measurement of the Lamb shift in muonic hydrogen yields a charge radius of the proton that is smaller than the CODATA value by about 5 standard deviations. We explore the possibility that new scalar, pseudoscalar, vector, and tensor flavor-conserving nonuniversal interactions may be responsible for the discrepancy. We consider exotic particles that, among leptons, couple preferentially to muons and mediate an attractive nucleon-muon interaction.

Six-lepton Z' resonance at the Large Hadron Collider.

New physics models admit the interesting possibility of a Z' weak boson associated with an extra U(1) gauge symmetry and a Higgs boson that is heavy enough to decay into a pair of Z bosons. Then Z' production and decay via Z' --> ZH --> ZZZ has a distinctive LHC signal that is nearly background-free and reconstructs the H and Z' masses and widths. The Z' decay to 3 pairs of leptons is especially distinctive.

Minimal gauged U(1) B-L model with spontaneous R parity violation.

We study the minimal gauged U(1) B-L supersymmetric model and show that it provides an attractive theory for spontaneous R-parity violation. Both U(1) B-L and R parity are broken by the vacuum expectation value of the right-handed sneutrino (proportional to the soft supersymmetry masses), thereby linking the B-L and soft SUSY scales. In this context we find a consistent mechanism for generating neutrino masses and a realistic mass spectrum, all without extending the Higgs sector of the minimal supersymmetry standard model.

Top-quark pairs at high invariant mass: a model-independent discriminator of new physics at the Large Hadron Collider.

We study top-quark pair production to probe new physics at the CERN Large Hadron Collider. We propose reconstruction methods for tt[over] semileptonic events and use them to reconstruct the tt[over] invariant mass. The angular distribution of top quarks in their c.

Solar mass-varying neutrino oscillations.

We propose that the solar neutrino deficit may be due to oscillations of mass-varying neutrinos (MaVaNs). This scenario elucidates solar neutrino data beautifully while remaining comfortably compatible with atmospheric neutrino and K2K data and with reactor antineutrino data at short and long baselines (from CHOOZ and KamLAND). We find that the survival probability of solar MaVaNs is independent of how the suppression of neutrino mass caused by the acceleron-matter couplings varies with density.

Unknowns after the SNO charged-current measurement.

We perform a model-independent analysis of solar neutrino flux rates including the recent charged-current measurement at the Sudbury Neutrino Observatory (SNO). We derive a universal sum rule involving SNO and SuperKamiokande rates, and show that the SNO neutral-current measurement cannot fix the fraction of solar nu(e) oscillating to sterile neutrinos. The large uncertainty in the standard solar model (8)B flux impedes a determination of the sterile neutrino fraction.

CPT-Odd resonances in neutrino oscillations.

We consider the consequences for future neutrino factory experiments of small CPT-odd interactions in neutrino oscillations. The nu(&mgr;)-->nu(&mgr;) and nu;(&mgr;)-->nu;(&mgr;) survival probabilities at a baseline L = 732 km can test for CPT-odd contributions at orders of magnitude better sensitivity than present neutrino sector limits. Interference between the CPT-violating interaction and CPT-even mass terms in the Lagrangian can lead to a resonant enhancement of the oscillation amplitude.