arXiv subjects

Katherine Schwind

Publications and source records attributed to Katherine Schwind.

7 recordsLinked to original sources

arXiv2025

The Lepton-Gluon Portal Beyond Lepto-Gluons

We explore models where single new exotic states interact with the Standard Model through an asymmetric Standard Model portal with couplings to at least one gluon and one lepton. We consider the complete set of effective operators up to dimension 6, and examine a few additional dimension 7 operators that contain interesting field content or potential collider signals. The lepton-gluon portal allows access to exotic states with an interesting range of SU(3) and SU(2) quantum numbers. Finally, we explore potential single-production modes and their phenomenological signatures at colliders.

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arXiv2025

Portals to New Physics: The W-Quark Portal

We explore new EFT operators where single new exotic states interact with the Standard Model through an asymmetric Standard Model portal with couplings to at least one quark and one W boson. Effective operators up to dimension 6 are considered, and we specify SM charges of all new states accessible through this portal. We explore our interactions by detailing possible collider production processes at e-p and p-p colliders. Finally, we study the LHC production of a new weak-quadruplet SU(3) fundamental fermion which can be singly produced in association with a SM quark through W-quark portal processes.

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arXiv2024

The quark-lepton portal beyond leptoquarks

We explore models where single new exotic states interact with the Standard Model through an asymmetric Standard Model portal with couplings to at least one quark and one lepton. All effective operators up to dimension six where such interactions couple the SM to spin 0 and spin 1/2 particles are written down, and the exotic states accessible through the portal are identified. We note interactions that couple the SM to new particles with exotic combinations of baryon and lepton numbers, states of higher electric charge, and particles with unusual SM charge, including states in higher-dimensional representations of both SU(3) and SU(2). Finally, we discuss the phenomenology of these interactions, including novel particle decays, and we classify some of the collider production modes for exotic states at the LHC, LHeC and muon colliders.

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arXiv2024

Strong-Weak Bi-Adjoints, Gluon-W resonances, and new asymmetric LHC production processes

We study a novel production and decay mechanism for a bi-adjoint spin zero particle in the ($8,3,0$) representation of the Standard Model gauge groups. This work is part of a series studying new production processes for exotic particles in higher representations of Standard Model color and weak charge. Here, we study a specific new dimension 5 effective operator model which couples an exotic bi-adjoint scalar field to the SU(3) and SU(2) field strength tensors. The W-gluon resonant decay of the charged component of this new exotic field is explored. We discuss LHC production modes of both the charged and neutral bi-adjoint states and find a new single production mode for the charged state. This is the dominant LHC production mode for TeV-scale masses. We introduce a new HL-LHC search in which a single bi-adjoint is produced in association with a hard forward quark jet from asymmetric W-gluon fusion. This search yields a 5-sigma discovery potential for bi-adjoint masses up to 3 TeV for 10 TeV scalar effective operator cutoffs. We also find 2-sigma sensitivity at the HL-LHC for bi-adjoint masses up to 4 TeV and effective cutoffs in the 15 TeV range for the full 3 inverse atto-barn data set.

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arXiv2024

Unusual portals to new exotics, the W-gluon portal

We explore models where new light exotic states interact with the Standard Model through an asymmetric di-boson portal with one gluon and one W boson. We consider the complete set of effective operators up to dimension 6 which couple a single light exotic (LEX) state to at least one W boson and 1 gluon. Other Standard Model particles may also be present in the interactions. We discover that the W-gluon portal allows us to access a large array of exotic states in non-trivial representations of SU(3) and SU(2). We discuss new single production collider modes and phenomenological signatures for these light exotic states at LHC and e-p colliders.

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arXiv2024

Leptonic signatures of color-sextet scalars II: Exploiting unique large-$E_{\text{T}}^{\text{miss}}$ signals at the LHC

The diverse and distinct collider phenomenology of color-sextet scalars motivates thorough investigation of their effective couplings to the Standard Model at the LHC. Some of the more unique sextet signals involve not only jets but also leptons. In previous work, we proposed an LHC search for color-sextet scalars in a channel with jets and a hard opposite-sign lepton pair, which results from a dimension-six coupling. In this sequel we study the counterpart processes with neutrinos, which produce jets in association with missing transverse energy ($E_{\text{T}}^{\text{miss}}$) in addition to possible leptons. We consider multiple search channels, including both single and pair sextet production, all characterized by significant missing energy and some featuring distinctive kinematic features. Our multifaceted study consists of three reinterpreted existing searches and a joint-likelihood analysis designed by us to maximize HL-LHC sensitivity to single sextet production. We show that our dedicated strategy in the jets + lepton + $E_{\text{T}}^{\text{miss}}$ channel can supersede today's limits from reinterpreted searches, and we make sensitivity projections for the HL-LHC. Altogether, our analysis can exclude sextet scalars lighter than 4.4 TeV or probe effective cutoffs as high as 16.8 TeV.

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arXiv2022

Leptonic signatures of color-sextet scalars

Color-sextet scalars could have an array of possible couplings to the Standard Model beyond their well known renormalizable couplings to quark pairs. The next-largest couplings these scalars might enjoy have mass dimension six, and some include electroweak fields and can therefore produce highly distinctive signals at hadron colliders. Here we study the single production of color-sextet scalars in association with a hard lepton, which results from a dimension-six coupling to leptons in addition to quarks and gluons. We identify parameter space in which these scalars decay promptly and propose a search for such particles in final states with two jets and an opposite-charge lepton pair, one member of which has high momentum. We then impose our selection criteria on the proposed signal and its leading backgrounds to project the discovery potential and exclusion limits during the next runs of the LHC. We compare our search with existing searches for leptoquarks, and we find we achieve much higher sensitivity with our tailored approach due to the unique kinematics of leptonic sextet events.

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