Color octet scalars and high p_T four-jet events at the LHC

We study the effect of color octet scalars on the high transverse momenta four-jet cross section at the LHC. We consider both weak singlet and doublet scalars, concentrating on the case of small couplings to quarks. We find that a relatively early discovery at the LHC is possible for a range of scalar masses

Dark Matter from Unification of Color and Baryon Number

We analyze a recently proposed extension of the Standard Model based on the SU(4) x SU(2)_L x U(1)_X gauge group, in which baryon number is interpreted as the fourth color and dark matter emerges as a neutral partner of the ordinary quarks under SU(4). We show that under well-motivated minimal flavor-violating assumptions the particle spectrum contains a heavy dark matter candidate which is dominantly the partner of the right-handed top quark. Assuming a standard cosmology, the correct thermal relic density through freeze-out is obtained for dark matter masses around 2 - 3 TeV. We examine the constraints and future prospects for direct and indirect searches for dark matter. We also briefly discuss the LHC phenomenology, which is rich in top quark signatures, and investigate the prospects for discovery at a 100 TeV hadron collider.Comment: 6 pages, 5 figure

Baryon Number as the Fourth Color

We propose an extension of the Standard Model in which baryon number is promoted to be part of a non-Abelian gauge symmetry at high energies. Specifically, we consider the gauge group SU(4) x SU(2)_L x U(1)_X, where the SU(4) unifies baryon number and color. This symmetry is spontaneously broken down to the Standard Model gauge group at a scale which can be as low as a few TeV. The SU(4) structure implies that each SM quark comes along with an uncolored quark partner, the lightest of which is stabilized by the generalized baryon number symmetry and can play the role of dark matter. We explore circumstances under which one can realize a model of asymmetric dark matter whose relic abundance is connected to the observed baryon asymmetry, and discuss unique signatures that can be searched for at the LHC.Comment: 6 pages, 3 figure

B and L at the SUSY Scale, Dark Matter and R-parity Violation

We present a simple theory where baryon and lepton numbers are spontaneously broken at the supersymmetry scale. In this context R-parity must be spontaneously broken but the theory still contains a stable field which can play the role of the cold dark matter of the Universe. We discuss the spectrum of the theory, the properties of the dark matter candidate and the predictions for direct detection experiments. This theory provides a concrete example of exotic supersymmetric signatures associated with having the simultaneous presence of R-parity violating and missing energy signals at the Large Hadron Collider

Higgs boson decays, baryon number violation, and supersymmetry at the LHC

Baryon number violating interactions could modify the signatures of supersymmetric models at the Large Hadron Collider. In this article we investigate the predictions for the Higgs mass and the Higgs decays in a simple extension of the minimal supersymmetric standard model where the local baryon and lepton numbers are spontaneously broken at the TeV scale. This theory predicts baryon number violation at the low scale which can change the current LHC bounds on the supersymmetric spectrum. Using the ATLAS and CMS bounds on the Higgs mass we show the constraints on the sfermion masses, and show the subsequent predictions for the radiative Higgs decays. We found that the Higgs decay into two photons is suppressed due to the existence of new light leptons. In this theory the stops can be very light in agreement with all experimental bounds and we make a brief discussion of the possible signals at the LHC

Asymmetric Dark Matter and Baryogenesis from SU(2)ℓSU(2)_{\ell}

We propose a theory in which the Standard Model gauge symmetry is extended by a new $SU(2)_\ell$ group acting nontrivially on the lepton sector which is spontaneously broken at the TeV scale. Under this $SU(2)_\ell$ the ordinary leptons form doublets along with new lepton partner fields. This construction naturally contains a dark matter candidate, the partner of the right-handed neutrino, stabilized by a residual global $U(1)_\chi$ symmetry. We show that one can explain baryogenesis through an asymmetric dark matter scenario, in which generation of related asymmetries in the dark matter and baryon sectors is driven by the $SU(2)_\ell$ instantons during a first order phase transition in the early universe.Comment: Version accepted for publication in Physical Review D. 11 pages, 4 figures. References added, minor change

Simplified models with baryon number violation but no proton decay

We enumerate the simplest models that have baryon number violation at the classical level but do not give rise to proton decay. These models have scalar fields in two representations of SU(3)×SU(2)×U(1) and violate baryon number by two units. Some of the models give rise to nn̅ (neutron-antineutron) oscillations, while some also violate lepton number by two units. We discuss the range of scalar masses for which nn̅ oscillations are measurable in the next generation of experiments. We give a brief overview of the phenomenology of these models and then focus on one of them for a more quantitative discussion of nn̅ oscillations, the generation of the cosmological baryon number, the electric dipole moment of the neutron, and K^0-K̅^0 mixing

Phenomenology of scalar leptoquarks

We study the simplest renormalizable scalar leptoquark models where the standard model is augmented only by one additional scalar representation of SU(3)×SU(2)×U(1). The requirement that there be no proton decay from renormalizable interactions singles out two such models, one of which exhibits an unusual top mass enhancement of the μ→eγ decay rate. We analyze the phenomenology of the model with the unusual top mass enhancement of loop level chirality changing charged lepton processes in the light of existing and upcoming experiments. Both of the models that do not allow proton decay from renormalizable interactions have dimension-5 operators that, even if suppressed by the Planck scale, can give rise to an unacceptably high level of baryon number violation. We discuss symmetries that can forbid these dimension-5 operators

Color octet scalars and high pT four-jet events at LHC

We study the effect of color octet scalars on the high transverse momenta four-jet cross section at the LHC. We consider both weak singlet and doublet scalars, concentrating on the case of small couplings to quarks. We find that a relatively early discovery at the LHC is possible for a range of scalar masses.Comment: 5 pages, 9 figure