166 research outputs found
Signs of heavy Higgs bosons at CLIC: An road to the Electroweak Phase Transition
We analyse the sensitivity of the proposed Compact Linear Collider (CLIC) to
the existence of beyond the Standard Model (SM) Higgs bosons through their
decays into pairs of massive gauge bosons and SM-like Higgses , considering CLIC centre of mass energies TeV and TeV.
We find that resonant di-Higgs searches at CLIC would allow for up to two
orders of magnitude improvement w.r.t. the sensitivity achievable by HL-LHC in
the mass range . Focusing then
on a real singlet extension of the SM, we explore the prospects of heavy Higgs
searches at CLIC for probing the regions of parameter space yielding a strongly
first order electroweak phase transition that could generate the observed
matter-antimatter asymmetry of the Universe. Our study illustrates the
complementarity between CLIC and other possible future colliders like FCC-ee in
probing singlet extensions of the SM, and shows that high-energy
colliders provide a powerful means to unravel the nature of electroweak
symmetry breaking in the early Universe.Comment: 27 pages, 15 figure
Boosted objects at the LHC
Almost all theoretical extensions of the Standard Model predict heavy TeV-scale resonances which have to couple to electroweak-scale resonances, e.g., top quarks or electroweak gauge bosons. Therefore, boosted electroweak-scale resonances with large branching ratios into jets is a highly probable scenario in many processes probing new physics. Here, jet substructure methods can help to
disentangle the sought-after signal from the backgrounds. In this brief review we classify scenarios where jet substructure methods can be beneficial for new physics
searches at the LHC and discuss the application of the HEPTopTagger in some of these scenarios
Searches for vector-like quarks at future colliders and implications for composite Higgs models with dark matter
Many composite Higgs models predict the existence of vector-like quarks with masses outside the reach of the LHC, e.g. mQ 73 2 TeV, in particular if these models contain a dark matter candidate. In such models the mass of the new resonances is bounded from above to satisfy the constraint from the observed relic density. We therefore develop new strategies to search for vector-like quarks at a future 100 TeV collider and evaluate what masses and interactions can be probed. We find that masses as large as 3c 6.4 ( 3c9) TeV can be tested if the fermionic resonances decay into Standard Model (dark matter) particles. We also discuss the complementarity of dark matter searches, showing that most of the parameter space can be closed. On balance, this study motivates further the consideration of a higher-energy hadron collider for a next generation of facilities
Boosting Higgs discovery - the forgotten channel
Searches for a heavy Standard Model Higgs boson focus on the 'gold plated
mode' where the Higgs decays to two leptonic Z bosons. This channel provides a
clean signature, in spite of the small leptonic branching ratios. We show that
using fat jets the semi-leptonic ZZ mode significantly increases the number of
signal events with a similar statistical significance as the leptonic mode.Comment: 12 pages, 3 figure
Spontaneous Symmetry Breaking through Mixing
We discuss a model, in which the negative mass square needed in the Higgs
mechanism is generated by mixing with a heavy scalar. We have two scalar
doublets in the standard model. Phenomenological properties of the heavy new
scalar are discussed. The heavy scalar can be detected by the LHC.Comment: 4 page
All-in-one relaxion: A unified solution to five particle-physics puzzles
We present a unified relaxion solution to the five major outstanding issues in particle physics: Higgs mass naturalness, dark matter, matter-antimatter asymmetry, neutrino masses and the strong CP problem. The only additional field content in our construction with respect to standard relaxion models is an up-type vectorlike fermion pair and three right-handed neutrinos charged under the relaxion shift symmetry. The observed dark matter abundance is generated automatically by oscillations of the relaxion field that begin once it is misaligned from its original stopping point after reheating. The matter-antimatter asymmetry arises from spontaneous baryogenesis induced by the CPT violation due to the rolling of the relaxion after reheating. The CPT violation is communicated to the baryons and leptons via an operator, ∂μϕJμ, where Jμ consists of right-handed neutrino currents arising naturally from a simple neutrino mass model. Finally, the strong CP problem is solved via the Nelson-Barr mechanism, i.e., by imposing CP as a symmetry of the Lagrangian that is broken only spontaneously by the relaxion. The CP breaking is such that although an Oð1Þ strong Cabibbo-Kobayashi-Maskawa (CKM) phase is generated, the induced strong CP phase is much smaller, i.e., within experimental bounds
NLO QCD corrections to processes with multiple electroweak bosons
The VBFNLO program package is a collection of Monte Carlo programs for the
calculation of NLO QCD corrections to vector boson fusion cross sections,
double and triple vector boson production, or the production of two electroweak
bosons in association with an additional jet. An overview is given of the
processes and features implemented in VBFNLO. WWgamma and Wgamma jet production
are discussed as examples.Comment: 6 pages, 3 figures; talk given at RADCOR 2009 - 9th International
Symposium on Radiative Corrections (Applications of Quantum Field Theory to
Phenomenology), October 25 - 30 2009, Ascona, Switzerlan
Higgs Discovery through Top-Partners using Jet Substructure
Top-partners -- vector-like quarks which mix predominantly with the top quark
-- are simple extensions of the standard model present in many theories of new
physics such as little Higgs models, topcolor models, and extra dimensions.
Through renormalizable mixing with the top quark, these top-partners inherit
couplings to the Higgs boson. Higgs bosons produced from the decay of
top-partners are often highly boosted and ideal candidates for analyses based
on jet substructure. Using substructure methods, we show that light Higgs
bosons decaying to b b-bar can be discovered at the 14 TeV LHC with less than
10 inverse fb for top-partner masses up to 1 TeV.Comment: 11 pages, 7 figure
- …