Color-octet scalars in Dirac gaugino models with broken R symmetry

Abstract

In this work we study the collider phenomenology of color-octet scalars (sgluons) in supersymmetric models with Dirac gaugino masses that feature an explicitly broken R symmetry (R-broken models). We construct such models by augmenting minimal R-symmetric models with a fairly general set of supersymmetric and softly supersymmetry-breaking operators that explicitly break R symmetry. We then compute the rates of all significant two-body decays and highlight new features that appear as a result of R symmetry breaking, including enhancements to extant decay rates, novel tree- and loop-level decays, and improved cross sections of single sgluon production. We demonstrate in some detail how the familiar results from minimal R-symmetric models can be obtained by restoring R symmetry. In parallel to this discussion, we explore constraints on these models from the Large Hadron Collider. We find that, in general, R symmetry breaking quantitatively affects existing limits on color-octet scalars, perhaps closing loopholes for light CP-odd (pseudoscalar) sgluons while opening one for a light CP-even (scalar) particle. Qualitatively, however, we find that — much as for minimal R-symmetric models, despite stark differences in phenomenology — scenarios with broken R symmetry and two sgluons below the TeV scale can be accommodated by existing searches.

Top-philic heavy resonances in four-top final states and their EFT interpretation

“…Moreover, the pp → tttt process could also be mediated by new top-philic particles, as predicted by a variety of new physics scenarios [5][6][7][8][9][10]. Examples of such new particles arise in composite Higgs solutions to the hierarchy problem [11][12][13][14][15][16], in models based on minimal flavour violation [17,18], in models featuring extended supersymmetries [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34], or simply when the particle spectrum includes additional scalar fields interacting with the Standard Model via their mixing with the Higgs boson. The phenomenology of light top-philic particles, i.e.…”

$$ t\overline{t}t\overline{t} $$ signatures through the lens of color-octet scalars

“…We begin with a brief review of models featuring Dirac gauginos and adjoint scalars, quickly pivoting to discuss the effective interactions of the latter with the Standard Model relevant to the cross section σ(pp → t tt t) at the LHC. This discussion serves to establish notation and to make contact with [63] and [67] and the broader literature before proceeding with our analysis.…”

“…A fair share of that attention has gone to the aforementioned adjoint scalars, particularly the SU(3) c adjoint (color-octet) scalars (sgluons) [59][60][61][62][63][64], though the weak hypercharge adjoint has been used to explain experimental anomalies in the past [65,66] and the weak-isospin adjoints have been scrutinized more recently [67,68]. The color-octet scalars -of which there are two, a scalar and a pseudoscalar, if they conserve CP -couple at tree level only to colored supersymmetric particles and gluons, the latter of which allows copious pair production at the LHC.…”

“…In models with minimal particle content, at least, the latter coupling is proportional to the quark mass, implying that only the coupling to a t t pair is non-negligible in most cases. While sgluon decays to top quarks have been studied both at the dawn of the LHC era [59,60] and more recently [62,63,67,69], the recent ATLAS measurement offers us a new opportunity to scrutinize these particles' contributions to the four-top cross section. In general, the sgluon pair production cross sections in these models are large enough that branching fractions to t t of at least O(1)% should lead to detectable signatures in searches for final states with multiple top quarks.…”

Exploring the phenomenology of weak adjoint scalars in minimal R-symmetric models

“…Recently, particular attention has been paid to the strong sectors of such models and the interactions of the color-octet sgluons [10][11][12][13][14][15]. Here, we turn our attention to the weak sector and examine the behavior of the scalar singlet and SU(2) triplet fields.…”