The LHC Phenomenology of Vectorlike Confinement

We investigate in detail the LHC phenomenology of "vectorlike confinement", where the Standard Model is augmented by a new confining gauge interaction and new light fermions that carry vectorlike charges under both the Standard Model and the new gauge group. If the new interaction confines at the TeV scale, this framework gives rise to a wide range of exotic collider signatures such as the production of a vector resonance that decays to a pair of collider-stable charged massive particles (a "di-CHAMP" resonance), to a pair of collider-stable massive colored particles (a "di-R-hadron resonance), to multiple photons, $W$s and $Z$s via two intermediate scalars, and/or to multi-jet final states. To study these signals at the LHC, we set up two benchmark models: one for the di-CHAMP and multi-photon signals, and the other for the di-R-hadron and multijet signals. For the di-CHAMP/multi-photon model, Standard Model backgrounds are negligible, and we show that a full reconstruction of the spectrum is possible, providing powerful evidence for vectorlike confinement. For the di-R-hadron/multijet model, we point out that in addition to the di-R-hadron signal, the rate of the production of four R-hadrons can also be sizable at the LHC. This, together with the multi-jet signals studied in earlier work, makes it possible to single out vectorlike confinement as the underlying dynamics.Comment: 32 pages, 28 figures. Several typos fixed, one paragraph added elaborating choice of benchmarks. Version accepted by JHEP

Low Energy 6-Dimensional N=2 Supersymmertric SU(6) Models on T2T^2 Orbifolds

We propose low energy 6-dimensional N=2 supersymmetric SU(6) models on $M^4\times T^2/(Z_2)^3$ and $M^4\times T^2/(Z_2)^4$, where the orbifold $SU(3)_C\times SU(3)$ model can be embedded on the boundary 4-brane. For the zero modes, the 6-dimensional N=2 supersymmetry and the SU(6) gauge symmetry are broken down to the 4-dimensional N=1 supersymmetry and the $SU(3)_C\times SU(2)_L\times U(1)_Y\times U(1)'$ gauge symmetry by orbifold projections. In order to cancel the anomalies involving at least one $U(1)'$, we add extra exotic particles. We also study the anomaly free conditions and present some anomaly free models. The gauge coupling unification can be achieved at $100\sim 200$ TeV if the compactification scale for the fifth dimension is $3\sim 4$ TeV. The proton decay problem can be avoided by putting the quarks and leptons/neutrinos on different 3-branes. And we discuss how to break the $SU(3)_C\times SU(2)_L\times U(1)_Y\times U(1)'$ gauge symmetry, solve the $\mu$ problem, and generate the $Z-Z'$ mass hierarchy naturally by using the geometry. The masses of exotic particles can be at the order of 1 TeV after the gauge symmetry breaking. We also forbid the dimension-5 operators for the neutrino masses by $U(1)'$ gauge symmetry, and the realistic left-handed neutrino masses can be obtained via non-renormalizable terms.Comment: Latex, 33 pages, discussion and references adde

Vectorlike Confinement at the LHC

We argue for the plausibility of a broad class of vectorlike confining gauge theories at the TeV scale which interact with the Standard Model predominantly via gauge interactions. These theories have a rich phenomenology at the LHC if confinement occurs at the TeV scale, while ensuring negligible impact on precision electroweak and flavor observables. Spin-1 bound states can be resonantly produced via their mixing with Standard Model gauge bosons. The resonances promptly decay to pseudo-Goldstone bosons, some of which promptly decay to a pair of Standard Model gauge bosons, while others are charged and stable on collider time scales. The diverse set of final states with little background include multiple photons and leptons, missing energy, massive stable charged particles and the possibility of highly displaced vertices in dilepton, leptoquark or diquark decays. Among others, a novel experimental signature of resonance reconstruction out of massive stable charged particles is highlighted. Some of the long-lived states also constitute Dark Matter candidates.Comment: 33 pages, 6 figures. v4: expanded discussion of Z_2 symmetry for stability, one reference adde

KeV Warm Dark Matter and Composite Neutrinos

Elementary keV sterile Dirac neutrinos can be a natural ingredient of the composite neutrino scenario. For a certain class of composite neutrino theories, these sterile neutrinos naturally have the appropriate mixing angles to be resonantly produced warm dark matter (WDM). Alternatively, we show these sterile neutrinos can be WDM produced by an entropy-diluted thermal freeze-out, with the necessary entropy production arising not from an out-of-equilibrium decay, but rather from the confinement of the composite neutrino sector, provided there is sufficient supercooling.Comment: 12 pages, 2 figures, published versio

LHC String Phenomenology

We argue that it is possible to address the deeper LHC Inverse Problem, to gain insight into the underlying theory from LHC signatures of new physics. We propose a technique which may allow us to distinguish among, and favor or disfavor, various classes of underlying theoretical constructions using (assumed) new physics signals at the LHC. We think that this can be done with limited data $(5-10 fb^{-1})$, and improved with more data. This is because of two reasons -- a) it is possible in many cases to reliably go from (semi)realistic microscopic string construction to the space of experimental observables, say, LHC signatures. b) The patterns of signatures at the LHC are sensitive to the structure of the underlying theoretical constructions. We illustrate our approach by analyzing two promising classes of string compactifications along with six other string-motivated constructions. Even though these constructions are not complete, they illustrate the point we want to emphasize. We think that using this technique effectively over time can eventually help us to meaningfully connect experimental data to microscopic theory.Comment: 50 Pages, 13 Figures, 3 Tables, v2: minor changes, references adde

Neutrino Mass and μ→e+γ\mu \rightarrow e + \gamma from a Mini-Seesaw

The recently proposed "mini-seesaw mechanism" combines naturally suppressed Dirac and Majorana masses to achieve light Standard Model neutrinos via a low-scale seesaw. A key feature of this approach is the presence of multiple light (order GeV) sterile-neutrinos that mix with the Standard Model. In this work we study the bounds on these light sterile-neutrinos from processes like \mu ---> e + \gamma, invisible Z-decays, and neutrinoless double beta-decay. We show that viable parameter space exists and that, interestingly, key observables can lie just below current experimental sensitivities. In particular, a motivated region of parameter space predicts a value of BR(\mu ---> e + \gamma) within the range to be probed by MEG.Comment: 1+26 pages, 7 figures. v2 JHEP version (typo's fixed, minor change to presentation, results unchanged

Simplified Models for LHC New Physics Searches

This document proposes a collection of simplified models relevant to the design of new-physics searches at the LHC and the characterization of their results. Both ATLAS and CMS have already presented some results in terms of simplified models, and we encourage them to continue and expand this effort, which supplements both signature-based results and benchmark model interpretations. A simplified model is defined by an effective Lagrangian describing the interactions of a small number of new particles. Simplified models can equally well be described by a small number of masses and cross-sections. These parameters are directly related to collider physics observables, making simplified models a particularly effective framework for evaluating searches and a useful starting point for characterizing positive signals of new physics. This document serves as an official summary of the results from the "Topologies for Early LHC Searches" workshop, held at SLAC in September of 2010, the purpose of which was to develop a set of representative models that can be used to cover all relevant phase space in experimental searches. Particular emphasis is placed on searches relevant for the first ~50-500 pb-1 of data and those motivated by supersymmetric models. This note largely summarizes material posted at http://lhcnewphysics.org/, which includes simplified model definitions, Monte Carlo material, and supporting contacts within the theory community. We also comment on future developments that may be useful as more data is gathered and analyzed by the experiments.Comment: 40 pages, 2 figures. This document is the official summary of results from "Topologies for Early LHC Searches" workshop (SLAC, September 2010). Supplementary material can be found at http://lhcnewphysics.or

Bose-Einstein Condensation, Dark Matter and Acoustic Peaks

Scalar mediated interactions among baryons extend well above the Compton wavelength, when they are embedded in a Bose-Einstein condensate composed of the mediating particles. Indeed, this non-trivial environment results in an infinite-ranged interaction. We show that if the Dark Matter of the Universe is composed of such a condensate, the imprints of an interaction between baryonic and Dark Matter could be manifest as anomalies in the peak structure of the Cosmic Microwave Background.Comment: 11 pages, 2 figures; changes reflect published versio

Effect of a Participatory Multisectoral Maternal and Newborn Intervention on Maternal Health Service Utilization and Newborn Care Practices: A Quasi-Experimental Study in Three Rural Ugandan Districts

Background: The MANIFEST study in eastern Uganda employed a participatory multisectoral approach to reduce barriers to access to maternal and newborn care services. Objectives: This study analyses the effect of the intervention on the utilization of maternal and newborn services and care practices. Methods: The quasi-experimental pre- and post-comparison design had two main components: community mobilization and empowerment, and health provider capacity building. The primary outcomes were utilization of antenatal care (ANC), delivery and postnatal care, and newborn care practices. Baseline (n = 2237) and endline (n = 1946) data were collected from women of reproductive age. The data was analysed using difference in differences (DiD) analysis and logistic regression. Results: The DiD results revealed an 8% difference in early ANC attendance (p < 0.01) and facility delivery (p < 0.01). Facility delivery increased from 66% to 73% in the intervention area, but remained unchanged in the comparison area (64% vs 63%, p < 0.01). The DiD results also demonstrated a 20% difference in clean cord care (p < 0.001) and an 8% difference in delayed bathing (p < 0.001). The intervention elements that predicted facility delivery were attending ANC four times [adjusted odds ratio (aOR) 1.42, 95% confidence interval (CI) 1.17–1.74] and saving for maternal health (aOR 2.11, 95% CI 1.39–3.21). Facility delivery and village health team (VHT) home visits were key predictors for clean cord care and skin-to-skin care. Conclusions: The multisectoral approach had positive effects on early ANC attendance, facility deliveries and newborn care practices. Community resources such as VHTs and savings are crucial to maternal and newborn outcomes and should be supported. VHT-led health education should incorporate practical measures that enable families to save and access transport services to enhance adequate preparation for birth.DFI