Pawin Ittisamai

Discovering Strong Top Dynamics at the LHC

We analyze the phenomenology of the top-pion and top-Higgs states in models with strong top dynamics, and translate the present LHC searches for the Standard Model Higgs into bounds on these scalar states. We explore the possibility that the new state at a mass of approximately 125 GeV observed at the LHC is consistent with a neutral pseudoscalar top-pion state. We demonstrate that a neutral pseudoscalar top-pion can generate the diphoton signal at the observed rate. However, the region of model parameter space where this is the case does not correspond to classic topcolorassisted technicolor scenarios with degenerate charged and neutral top-pions and a top-Higgs mass of order 2mt; rather, additional isospin violation would need to be present and the top dynamics would be more akin to that in top seesaw models. Moreover, the interpretation of the new state as a top-pion can be sustained only if the ZZ (four-lepton) and WW (two-lepton plus missing energy) signatures initially observed at the 3 level decline in signicance as additional data is accrued.

Technipion Limits from LHC Higgs Searches

Author(s): Chivukula, RS; Ittisamai, P; Simmons, EH; Ren, J | Abstract: LHC searches for the standard model Higgs Boson in γγ or ττ decay modes place strong constraints on the light technipion state predicted in technicolor models that include colored technifermions. Compared with the standard Higgs Boson, the technipions have an enhanced production rate (largely because the technipion decay constant is smaller than the weak scale) and also enhanced branching ratios into di-photon and di-tau final states (largely due to the suppression of WW decays of the technipions). These factors combine to make the technipions more visible in both channels than a standard model Higgs would be. Hence, the recent ATLAS and CMS searches for Higgs bosons exclude the presence of technipions with masses from 110GeV to nearly 2m t in technicolor models that (a)include colored technifermions (b)feature topcolor dynamics and (c)have technicolor groups with three or more technicolors (N TC3). For certain models, the limits also apply out to higher technipion masses or down to the minimum number of technicolors (N TC=2). The limits may be softened somewhat in models where extended technicolor plays a significant role in producing the top quarks mass. Additional LHC data on di-tau and di-photon final states will be extremely valuable in further exploring technicolor parameter space.

Color discriminant variable and scalar diquarks at the LHC

The LHC is actively searching for narrow dijet resonances corresponding to physics beyond the Standard Model. Among the many resonances that have been postulated (e.g., colored vectors, scalars, and fermions) one that would have a particularly large production rate at the LHC would be a scalar diquark produced in the s-channel via fusion of two valence quarks. In previous work, we introduced a color discriminant variable that distinguishes among various dijet resonances, drawing on measurements of the dijet resonance mass, total decay width and production cross-section. Here, we show that this model-independent method applies well to color-triplet and color-sextet scalar diquarks, distinguishing them clearly from other candidate resonances. We also introduce a more transparent theoretical formulation of the color discriminant variable that highlights its relationship to the branching ratios of the resonance into incoming and outgoing partons and to the properties of those partons. While the original description of the color discriminant variable remains convenient for phenomenological use upon discovery of a new resonance, the new formulation makes it easier to predict the value of the variable for a given class of resonance.

Coloron Models and LHC Phenomenology

Author(s): Simmons, Elizabeth H; Atre, Anupama; Chivukula, R Sekhar; Ittisamai, Pawin; Vignaroli, Natascia; Farzinnia, Arsham; Foadi, Roshan | Abstract: This talk discusses the possibility of new physics within the strong gauge interactions, specifically the idea of an extended color gauge group that is spontaneously broken to QCD. After a brief review of the literature, three of our recent pieces of work on coloron phenomenology are summarized. First, some key results on coloron production to NLO at hadron colliders are described. Next, a method of using associated production of colorons and weak vector bosons to better determine coloron couplings is discussed. Finally, a new model that naturally realizes flavor physics is reviewed.

Technicolor in the LHC Era

LHC searches for the standard model Higgs Boson in \gamma\gamma\ or \tau\tau\ decay modes place strong constraints on the light technipion state predicted in technicolor models that include colored technifermions. Compared with the standard Higgs Boson, the technipions have an enhanced production rate (largely because the technipion decay constant is smaller than the weak scale) and also enhanced branching ratios into di-photon and di-tau final states (largely due to the suppression of WW decays of the technipions). Recent ATLAS and CMS searches for Higgs bosons exclude the presence of technipions with masses from 110 GeV to nearly 2m_t in technicolor models that (a) include colored technifermions (b) feature topcolor dynamics and (c) have technicolor groups with three or more technicolors (N_{TC} > 3).

Distinguishing Color-Octet and Color-Singlet Resonances at the Large Hadron Collider

Dijet resonance searches are simple, yet powerful and model-independent, probes for discovering new particles at hadron colliders. Once such a resonance has been discovered it is important to determine the mass, spin, couplings, chiral behavior and color properties to determine the underlying theoretical structure. We propose a new variable which, in the absence of decays of the resonance into new nonstandard states, distinguishes between color-octet and color-singlet resonances. To keep our study widely applicable we study phenomenological models of color-octet and color-singlet resonances in flavor universal as well as flavor nonuniversal scenarios. We present our analysis for a wide range of mass (2.5\char21{}6 TeV), couplings and flavor scenarios for the LHC with center of mass energy of 14 TeV and varying integrated luminosities of 30, 100, 300 and

Probing Color Octet Couplings at the Large Hadron Collider

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Simplified Limits on Resonances at the LHC

. We find encouraging results to distinguish color-octet and color-singlet resonances for different flavor scenarios at the LHC.

Simplified Limits on New LHC Resonances

Color-octet resonances arise in many well motivated theories beyond the standard model. As colored objects they are produced copiously at the LHC and can be discovered in early searches for new physics in dijet final states. Once they are discovered it will be important to measure the couplings of the new resonances to determine the underlying theoretical structure. We propose a new channel, associated production of

Separating Dijet Resonances Using the Color Discriminant Variable

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