5 Search Results

The mirror twin Higgs model (MTH) is a solution to the Higgs hierarchy problem that provides well-predicted cosmological signatures with only three extra parameters: the temperature of the twin sector, the abundance of twin baryons, and the vacuum expectation value (VEV) of twin electroweak symmetry breaking. These parameters specify the behavior of twin radiation and the acoustic oscillations of twin baryons, which lead to testable effects on the cosmic microwave background (CMB) and large-scale structure (LSS). While collider searches can only probe the twin VEV, through a fit to cosmological data we show that the existing CMB (Planck18 TTTEEE+lowE+lowT+lensing) andmore » LSS (KV450) data already provide useful constraints on the remaining MTH parameters. Additionally, we show that the presence of twin radiation in this model can raise the Hubble constant H$$_{0}$$ while the scattering twin baryons can reduce the matter fluctuations S$$_{8}$$, which helps to relax the observed H$$_{0}$$ and S$$_{8}$$ tensions simultaneously. This scenario is different from the typical ΛCDM + ΔN$$_{eff}$$ model, in which extra radiation helps with the Hubble tension but worsens the S$$_{8}$$ tension. For instance, when including the SH0ES and 2013 Planck SZ data in the fit, we find that a universe with ≳ 20% of the dark matter comprised of twin baryons is preferred over ΛCDM by ~ 4σ. If the twin sector is indeed responsible for resolving the H$$_{0}$$ and S$$_{8}$$ tensions, future measurements from the Euclid satellite and CMB Stage 4 experiment will further measure the twin parameters to O(1 - 10%)-level precision. Our study demonstrates how models with hidden naturalness can potentially be probed using precision cosmological data.« less

We study soft and collinear gluon emission in squark decays to quark–neutralino pair, at next-to-next-to-leading logarithmic (NNLL) accuracy in the end-point region, using soft collinear effective theory (SCET), and at next-to-leading (NLO) fixed order in the rest of the phase space. As a phenomenological case study we discuss the impact of radiative corrections on the simultaneous measurements of squark and neutralino masses at a linear $e^+e^–$ collider based on $$\sqrt{s}$$ = 3 TeV Compact Linear Collider (CLIC), and show the softening of distributions in the sum of energies of the first two hardest jets or in the $$M_C$$ variable. Sincemore » the majority of mass measurement techniques are based on edges in kinematic distributions, and these change appreciably when there is additional QCD radiation in the final state, the knowledge of higher-order QCD effects is required for precise mass determinations.« less

We presenmore » t a model in which an up-type vectorlike quark (VLQ) is charged under a new $U(1{)}_d$ gauge force which kinetically mixes with the Standard Model hypercharge. The gauge boson of the $U(1{)}_d$ is the dark photon, ${\gamma }_d$. Traditional searches for VLQs rely on decays into Standard Model electroweak bosons $W$, $Z$, or Higgs. However, since no evidence for VLQs has been found at the Large Hadron Collider (LHC), it is imperative to search for other novel signatures of VLQs beyond their traditional decays. As we show, if the dark photon is much less massive than the Standard Model electroweak sector, $$M_{γd}$$ $$\ll$$ $$M_z$$, for the large majority of the allowed parameter space the VLQ predominately decays into the dark photon and the dark Higgs that breaks the $U(1{)}_d$. That is, this VLQ is a “maverick top partner” with nontraditional decays. One of the appeals of this scenario is that pair production of the VLQ at the LHC occurs through the strong force and the rate is determined by the gauge structure. Hence, the production of the dark photon at the LHC only depends on the strong force and is largely independent of the small kinetic mixing with hypercharge. This scenario provides a robust framework to search for a light dark sector via searches for heavy colored particles at the LHC.« less

We examine the discovery potential for double Higgs production at the high luminosity LHC in the final state with two b-tagged jets, two leptons and missing transverse momentum. Although this dilepton final state has been considered a difficult channel due to the large backgrounds, we argue that it is possible to obtain sizable signal significance, by adopting a deep learning framework making full use of the relevant kinematics along with the jet images from the Higgs decay. For the relevant number of signal events we obtain a substantial increase in signal sensitivity over existing analyses. We discuss relative improvements atmore » each stage and the correlations among the different input variables for the neutral network. The proposed method can be easily generalized to the semi-leptonic channel of double Higgs production, as well as to other processes with similar final states.« less

Here, we investigate the discovery potential of singly produced top-philic resonances at the high luminosity (HL) LHC in the four-top final state. Our analysis spans over the fully-hadronic, semi-leptonic, and same-sign dilepton channels where we present concrete search strategies adequate to a boosted kinematic regime and high jet-multiplicity environments. We utilize the Template Overlap Method (TOM) with newly developed template observables for tagging boosted top quarks, a large-radius jet variable $$M_J$$ and customized b-tagging tactics for background discrimination. Our results show that the same-sign dilepton channel gives the best sensitivity among the considered channels, with an improvement of significance upmore » to 10%-20% when combined with boosted-top tagging. Both the fully-hadronic and semi-leptonic channels yield comparable discovery potential and contribute to further enhancements in the sensitivity by combining all channels. Finally, we show the sensitivity of a top-philic resonance at the LHC and HL-LHC by showing the $$2\sigma$$ exclusion limit and $$5\sigma$$ discovery reach, including a combination of all three channels.« less