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We consider extensions of the standard model containing additional heavy particles ("quirks") charged under a new unbroken non-abelian gauge group as well as the standard model. We assume that the quirk mass m is in the phenomenologically interesting range 100 GeV-TeV, and that the new gauge group gets strong at a scale Λ < m. In this case breaking of strings is exponentially suppressed, and quirk production results in strings that are long compared to Λ −1 . The existence of these long stable strings leads to highly exotic events at colliders. For 100 eV < ∼ Λ < ∼ keV the strings are macroscopic, giving rise to events with two separated quirk tracks with measurable curvature toward each other due to the string interaction. For keV < ∼ Λ < ∼ MeV the typical strings are mesoscopic: too small to resolve in the detector, but large compared to atomic scales. In this case, the bound state appears as a single particle, but its mass is the invariant mass of a quirk pair, which has an event-by-event distribution. For MeV < ∼ Λ < ∼ m, the strings are microscopic, and the quirks annihilate promptly within the detector. For colored quirks, this can lead to hadronic fireball events with ∼ 10 3 hadrons with energy of order GeV emitted in conjunction with hard decay products from the final annihilation. arXiv:0805.4642v3 [hep-ph]

Long-lived colored particles with masses m > ∼ 200 GeV are allowed by current accelerator searches, and are predicted by a number of scenarios for physics beyond the standard model. We argue that such "heavy partons" effectively have a geometrical cross section (of order 10 mb) for annihilation at temperatures below the QCD deconfinement transition. The annihilation process involves the formation of an intermediate bound state of two heavy partons with large orbital angular momentum. The bound state subsequently decays by losing energy and angular momentum to photon or pion emission, followed by annihilation of the heavy partons. This decay occurs before nucleosynthesis for m < ∼ 10 11 GeV for electrically charged partons and m < ∼ TeV for electrically neutral partons. This implies that heavy parton lifetimes as long as 10 14 sec are allowed even for heavy partons with m ∼ TeV decaying to photons or hadrons with significant branching fraction.

We study how the exotic particles and supersymmetric partners would affect the discovery limit at the Tevatron and LHC for neutral gauge bosons in generic E 6 models. We examine the Z ′ decay in the extreme case that all of the particles are massless, then consider how the masses of non-standard model particles will affect the discovery limit. We also calculate the discovery limit for a supersymmetric E 6 model with a secluded sector as a concrete example of a model with a definite set of exotic particles. Its discovery limit is small compared with other E 6 models due to the U ′ (1) charge assignment.

We construct an anomaly free supersymmetric U (1) ′ model with a secluded U (1) ′ -breaking sector. We study the one-loop effective potential at finite temperature, and show that there exists a strong enough first order electroweak phase transition for electroweak baryogenesis (EWBG) because of the large trilinear term A h hSH d Hu in the tree-level Higgs potential. Unlike in the MSSM, the lightest stop can be very heavy. We consider the non-local EWBG mechanism in the thin wall regime, and find that within uncertainties the observed baryon number can be generated from the τ lepton contribution, with the secluded sector playing an essential role. The chargino and neutralino contributions and the implications for the Z ′ mass and electric dipole moments are briefly discussed. PACS numbers: 12.60. Jv, 12.60.Cn [ UPR-1063-T ] The baryon asymmetry of the universe has been measured by WMAP [1]. Combining their data with other CMB and large scale structure results, they obtain the ratio of baryon density n B to entropy density sTo generate the baryon asymmetry, the Sakharov criteria [2] must be satisfied: (1) Baryon number (B) violation; (2) C and CP violation; (3) A departure from thermal equilibrium. Electroweak (EW) baryogenesis is especially interesting because the Sakharov criteria can be satisfied in the Standard Model (SM) [3]. However, in the SM the electroweak phase transition (EWPT) cannot be strongly first order for the experimentally allowed Higgs mass, and the CP violation from the CKM matrix is too small. In the Minimal Supersymmetric Standard Model (MSSM), although there are additional sources of CP violation in the supersymmetry breaking parameters, a strong enough first order EWPT requires that the lightest stop quark mass be smaller than the top quark mass ∼ 175 GeV. Also, the mass of the lightest CP even Higgs must be smaller than 120 GeV, which leaves a small window above the current limit [4]. In the Next to Minimal Supersymmetric Standard Model (NMSSM), a trilinear term A h hSH d H u in the tree-level Higgs potential may induce a strong enough first order EWPT [5,6], and the effective µ parameter is given by h S from the Yukawa term hSH d H u in the superpotential in the best-motivated versions. However, most versions either involve a discrete symmetry and serious cosmological domain wall problems [7], or reintroduce the µ problem [6].The possibility of an extra U (1) ′ gauge symmetry is well-motivated in superstring constructions [8]. Similar to the NMSSM, an extra U (1) ′ can provide an elegant solution to the µ problem due to the Yukawa term hSH d H u [9,10]. However, there are no discrete symmetries or domain wall problems. The MSSM upper bound of M Z on the tree-level mass of the lightest MSSM Higgs scalar is relaxed, both in models with a U (1) ′ and in the NMSSM, because of the Yukawa term hSH d H u and the U (1) ′ D-term [11]. Higgs masses lighter than those allowed by LEP in the MSSM are also possible, with the limits relaxed by mixings between Higgs doublets and singlets. There are ...