Top Partners Research Articles

Factors affecting cloud computing adoption: perspectives of IT professionals

The purpose of this research is to study the factors affecting cloud computing adoption. This study used the technology-organisation-environment TOE framework as a baseline for the factors affecting cloud computing adoption. The specific factors in the TOE framework are relative advantage, compatibility, complexity, organisational readiness, top management support, competitive pressure, and business partner pressure. An online-based survey was employed to collect data from 106 IT managers, IT consultants, and IT professionals working in Saudi organisations. Using binary logistic regression analysis, the results revealed that top management is positively and significantly associated with the likelihood of cloud computing adoption. The findings offer organisations and cloud computing service providers with better understanding of factors affecting the adoption of cloud computing.

Beyond two generations

A review is presented of searches performed by CMS experiment for new particles produced in association with or decaying to top quarks, as well as heavy top partners. The analysis presented use data collected with CMS experiment during 2012, in proton-proton collisions at a centre-of-mass energy of 8 TeV.

Single top partner production in the Higgs to diphoton channel in the Littlest Higgs Model with T-parity

The top partner as a hallmark of the Littlest Higgs Model with T-parity (LHT model) has been extensively searched for during the Large Hadron Collider (LHC) Run-1. With the increasing mass limits on the top partner, the single production of the top partner will be dominant over the pair production. Under the constraints from the Higgs data, the electroweak precision observables and Rb, we find that the mass of T-even top partner (T+) has to be heavier than 730 GeV. Then, we investigate the observability of the single T-even top partner production through the process pp→T+j with the sequent decay T+→th in the di-photon channel in the LHT model at the LHC. We find that the mass of T+ can be excluded up to 800 GeV at 2σ level at 14 TeV LHC with the integrated luminosity L=3 ab−1.

Relationships Between Adult Male and Maturing Mountain Gorillas (Gorilla beringei beringei) Persist Across Developmental Stages and Social Upheaval

AbstractAcross the animal kingdom, long‐term social relationships outside the context of reproductive pair bonds are rare. However, they have been demonstrated in some mammals including primates, cetaceans, and social carnivores. The ontogeny of such relationships is likely to depend on the benefits individuals can gain by cultivating them. Previous studies demonstrated that young mountain gorillas (Gorilla beringei beringei) have strong relationships with adult males, but little is known about the longevity of these bonds. Here, we examine the temporal stability of proximity relationships between coresident adult male and maturing gorillas in the habituated population monitored by the Dian Fossey Gorilla Fund International's Karisoke Research Center in Volcanoes National Park, Rwanda. We used spatial proximity data to assess the strength of relationships between adult males and juveniles, and tracked these relationships as the juveniles matured into subadults (3–4 yr later; n = 229 dyads) and then young adults (7 yr later; n = 42 dyads). The proximity relationships of juveniles of both sexes predicted their proximity relationships with adult males in both subadulthood and young adulthood. However some young adult males who had lost their top adult male proximity partner from juvenilehood developed new relationships with older males that had risen in the dominance hierarchy. These data suggest that (1) kin selection may play a more important role in social relationships between potential fathers and adult female offspring than previously suspected, and (2) when maturing males' foremost adult male social partners remain available to them, their relationships can be stable past the age at which younger males become reproductive competitors.

Discovering uncolored naturalness in exotic Higgs decays

Solutions to the hierarchy problem usually require top partners. In standard SUSY or composite Higgs theories, the partners carry SM color and are becoming increasingly constrained by LHC searches. However, theories like Folded SUSY (FS), Twin Higgs (TH) and Quirky Little Higgs (QLH) introduce uncolored top partners, which can be SM singlets or carry electroweak charge. Their small production cross section left doubt as to whether the LHC can effectively probe such scenarios. Typically, these partners are charged under their own mirror color gauge group. In FS and QLH, the absence of light mirror matter allows glueballs to form at the bottom of the mirror spectrum. This is also the case in some TH realizations. The Higgs can decay to these mirror glueballs, with the glueballs decaying into SM particles with potentially observable lifetimes. We undertake the first detailed study of this glueball signature and quantitatively demonstrate the discovery potential of uncolored naturalness via exotic Higgs decays at the LHC and a potential future 100 TeV collider. Our findings indicate that mirror glueballs are the smoking gun signature of natural FS and QLH type theories, in analogy to tree-level Higgs coupling shifts for the TH. We show that glueball masses in the $\sim$ 10-60 GeV mass range are theoretically preferred. Careful treatment of lifetime, mirror-hadronization and nonperturbative uncertainties is required to perform meaningful collider studies. We outline several new search strategies for exotic Higgs decays of the form $h\to XX \to 4f$ at the LHC, with $X$ having lifetimes in the $10 \mu m$ to $km$ range. We find that FS stops can be probed with masses up to 600 (1100) GeV at the LHC with 300 (3000) /fb of data, and TH top partners could be accessible with masses up to 900 (1500) GeV. This makes exotic Higgs decays the prime discovery channel for uncolored naturalness at the LHC.

Composite Higgses with seesaw EWSB

We introduce a new class of Composite Higgs models in which electroweak symmetry is broken by a seesaw-like mechanism. If a global symmetry is broken sequentially at different scales, two sets of pseudo-Goldstone bosons will arise, one set being typically heavier than the other. If two Composite Higgs doublets mix, then the mass-squared of the lighter state can be driven negative, and induce EWSB. We illustrate with the example $SO(6) \rightarrow SO(5) \rightarrow SO(4)$, and derive an estimate of the light Higgs potential. We find that the introduction of an extra scale can ease many of the tensions present in conventional Composite Higgs models, especially those related to fine-tuning. In particular we find that we can significantly raise the upper bound on the mass of the elusive top partners.

Composite scalars at the LHC: the Higgs, the Sextet and the Octet

We present a phenomenological theory of scalar particles that transform as a sextet and an octet of QCD interactions. These particles may arise as light bound states of a fundamental dynamics giving rise to a composite Higgs boson and partial compositeness for the top. As a concrete example, we discuss an explicit UV completion based on the SU(4)/Sp(4) coset, where QCD colour is carried by additional fundamental fermions charged under the confining gauge group. Top partners, as well as potentially even lighter coloured scalars, arise as bound states of the coloured fermions. We study production and detection at LHC Run I and II of the octet and sextet, setting lower limits on masses and couplings to Standard Model particles using existing 8 TeV analyses. We finally explore prospects for the ongoing 13 TeV Run II: we focus on final states with two same sign leptons, that have the potential to discriminate the sextet.

Neutrino masses from neutral top partners

We present theories of `Natural Neutrinos' in which neutral fermionic top partner fields are simultaneously the right-handed neutrinos (RHN), linking seemingly disparate aspects of the Standard Model structure: a) The RHN top partners are responsible for the observed small neutrino masses, b) They help ameliorate the tuning in the weak scale and address the little hierarchy problem, and c) The factor of $3$ arising from $N_c$ in the top-loop Higgs mass corrections is countered by a factor $3$ from the number of vector-like generations of RHN. The RHN top partners may arise in pseudo-Nambu-Goldstone-Boson (pNGB) Higgs models such as the Twin Higgs, as well as more general Composite, Little, and Orbifold Higgs scenarios, and three simple example models are presented. This framework firmly predicts a TeV-scale seesaw, as the RHN masses are bounded to be below the TeV scale by naturalness. The generation of light neutrino masses relies on a collective breaking of lepton number, allowing for comparatively large neutrino Yukawa couplings and a rich associated phenomenology. The structure of the neutrino mass mechanism realizes in certain limits the Inverse or Linear classes of seesaw. Natural Neutrino models are testable at a variety of current and future experiments, particularly in tests of lepton universality, searches for lepton flavor violation, and precision electroweak and Higgs coupling measurements possible at high energy $e^+ e^-$ and hadron colliders.

Collider constraints on tuning in composite Higgs models

Two potential sources of tuning exist in composite Higgs models: one comes from keeping the Higgs VEV below the compositeness scale and one comes from keeping the Higgs light after constraints on the top partner masses are applied. We construct a measure that determines whether these tunings are independent or not and combines them appropriately. We perform a comprehensive scan of the parameter space for three explicit models and report the minimum tuning values compatible with existing collider constraints. Tuning values are given as functions of resonance masses and deviations to the Higgs couplings so the effect of future constraints can easily be quantified. The current minimum tuning in the minimal model is 2.5-5% and will be decreased to around 0.8-3.3% if no top partners are observed over the lifetime of the LHC

The Gravity Model of Indonesian Bilateral Trade

This study aims to examine the trade of Indonesia with 10 top export partner using the gravity model of trade. The panel regression analysis with fixed effect model was conducted in order to acknowledge the relationship among the variables Constant Gross Domestic Product, Per Capita Gross Domestic Product, transportation cost, and Real Effective Exchange Rate on export of Indonesia with 10 partners. This study using secondary data with panel regression analysis and research instruments were tested using chow test, hausman test and classical assumption test. The panel regression result showed that simultaneously and partially Constant Gross Domestic Product, Per Capita Gross Domestic Product, transportation cost and Real Effective Exchange Rate had significant effect on export of Indonesia.

LHC top partner searches beyond the 2 TeV mass region

We propose a new search strategy for heavy top partners at the early stages of the LHC run-II, based on lepton-jet final states. Our results show that final states containing a boosted massive jet and a hard lepton, in addition to a top quark and possibly a forward jet, offer a new window to both detecting and measuring top partners of mass ∼ 2TeV. Our resulting signal significance is comparable or superior to the same sign dilepton channels for top partner masses heavier than roughly 1 TeV. Unlike the di-lepton channel, the selection criteria we propose are sensitive both to 5/3 and 1/3 charge top partners and allow for full reconstruction of the resonance mass peak. Our search strategy utilizes a simplified b-tagging procedure and the Template Overlap Method to tag the massive boosted objects and reject the corresponding backgrounds. In addition, we propose a new, pileup insensitive method, to tag forward jets which characterize our signal events. We consider full effects of pileup contamination at 50 interactions per bunch crossing. We demonstrate that even in the most pessimistic pileup scenarios, the significance we obtain is sufficient to claim a discovery over a wide range of top partner parameters. While we focus on the minimal natural composite Higgs model, the results of this paper can be easily translated into bounds on any heavy partner with a $$ t\overline{t}Wj $$ final state topology.

Beyond the minimal top partner decay

Light top partners are the prime sign of naturalness in composite Higgs models. We explore here the possibility of non-standard top partner phenomenology. We show that even in the simplest extension of the minimal composite Higgs model, featuring an extra singlet pseudo Nambu-Goldstone boson, the branching ratios of the top partners into standard channels can be significantly altered, with no substantial change in the generated Higgs potential. Together with the variety of possible final states from the decay of the pseudo-scalar singlet, this motivates more extensive analyses in the search for the top partners.

Does the trade gravity model depend on trading partners? Some evidence from Vietnam and her 54 trading partners

This paper finds that the influence of trade gravity variables is dependent on trading partners. For instance, trade with rich nations is more sensitive to distance, economic size, and trading partners, openness of trading partners, and exchange rate, than trade with low income nations. Nonetheless, the paper suggests that the trade policy should not ignore the importance of the level of development, maintenance of close economic ties, and the influence of the ASEAN, APEC, and the WTO on trade in the long and short run. This is found for the bilateral trade relations between Vietnam and her top 54 trading partners over the period 1986 to 2010.

Interplay of vector-like top partner multiplets in a realistic mixing set-up

The ATLAS and CMS collaborations at the LHC have performed analyses on the existing data sets, studying the case of one vector-like fermion or multiplet coupling to the standard model Yukawa sector. In the near future, with more data available, these experimental collaborations will start to investigate more realistic cases. The presence of more than one extra vector-like multiplet is indeed a common situation in many extensions of the standard model. The interplay of these vector-like multiplet between precision electroweak bounds, flavour and collider phenomenology is a important question in view of establishing bounds or for the discovery of physics beyond the standard model. In this work we study the phenomenological consequences of the presence of two vector-like multiplets. We analyse the constraints on such scenarios from tree-level data and oblique corrections for the case of mixing to each of the SM generations. In the present work, we limit to scenarios with two top-like partners and no mixing in the down-sector.

Structure and formation of top networks in international trade, 2001–2010

We propose the construction of the international trade network based on top trade relations (i.e., country i is linked to country j if j is i's top trade partner). The constructed network captures most important relations in international trade. The overall network displays a tree-like hierarchical structure. It is organized around global central countries (especially the US, China, and Germany) under which there are more levels of local centers. We develop a model that uses country behavior in local triadic environment to account for the formation of such network structure. The census of triads confirms the applicability of this model.

Same sign di-lepton candles of the composite gluons

Composite Higgs models, where the Higgs boson is identified with the pseudo-Nambu-Goldstone-Boson (pNGB) of a strong sector, typically have light composite fermions (top partners) to account for a light Higgs. This type of models, generically also predicts the existence of heavy vector fields (composite gluons) which appear as an octet of QCD. These composite gluons become very broad resonances once phase-space allows them to decay into two composite fermions. This makes their traditional experimental searches, which are designed to look for narrow resonances, quite ineffective. In this paper, we as an alternative, propose to utilize the impact of composite gluons on the production of top partners to constrain their parameter space. We place constraints on the parameters of the composite resonances using the 8 TeV LHC data and also assess the reach of the 14 TeV LHC. We find that the high luminosity LHC will be able to probe composite gluon masses up to ∼ 6 TeV, even in the broad resonance regime.

Precision natural SUSY at CEPC, FCC-ee, and ILC

Testing the idea of naturalness is and will continue to be one of the most important goals of high energy physics experiments. It will play a central role in the physics program of future colliders. In this paper, we present projections of the reach of natural SUSY at future lepton colliders: CEPC, FCC-ee and ILC. We focus on the observables which give the strongest reach, the electroweak precision observables (for left-handed stops), and Higgs to gluon and photon decay rates (for both left- and right-handed stops). There is a “blind spot” when the stop mixing parameter X t is approximately equal to the average stop mass. We argue that in natural scenarios, bounds on the heavy Higgs bosons from tree-level mixing effects that modify the $$ hb\overline{b} $$ coupling together with bounds from b → sγ play a complementary role in probing the blind spot region. For specific natural SUSY scenarios such as folded SUSY in which the top partners do not carry Standard Model color charges, electroweak precision observables could be the most sensitive probe. In all the scenarios discussed in this paper, the combined set of precision measurements will probe down to a few percent in fine-tuning.

Discovering heavy new physics in boostedZchannels:Z→l+l−vsZ→νν¯

We propose a strategy for new physics searches in channels which contain a boosted $Z$ boson in the final state. Our proposal exploits the previously overlooked advantages of boosted $Z\rightarrow \nu \bar{\nu}$ topologies, where collimated neutrinos result in signals with large missing energy. We illustrate the advantage of this channel in a case study of singly produced TeV scale charge 2/3 fermionic top partners ($T'$) which decay to $t+Z$. A comparison with the di-leptonic channel reveals that signals with missing energy offer superior probes of new physics at TeV scales, despite the large $t\bar{t}$ backgrounds. The effect can be attributed to a factor of $\sim 3$ enhancement in the signal cross section, coming from the branching ratio of $Z\rightarrow \nu \bar{\nu}$. We exploit the unique event topology of singly produced top partners to suppress the $t\bar{t}$ background, as well as further improve on the existing proposals to detect $T'$ in the boosted di-lepton channel. Our conclusions on advantages of $Z\rightarrow \nu \bar{\nu}$ can be extended to most physics searches which utilize a boosted $Z$ boson in the final state.

How to decontaminate overlapping fat jets

At the LHC, tagging boosted heavy particle resonances which decay hadronically, such as top quarks and Higgs bosons, can play an essential role in new physics searches. In events with high multiplicity, however, the standard approach to tag boosted resonances by a large-radius fat jet becomes difficult because the resonances are not well-separated from other hard radiation. In this paper, we propose a different approach to tag and reconstruct boosted resonances by using the recently proposed mass-jump jet algorithm. A key feature of the algorithm is the flexible radius of the jets, which results from a terminating veto that prevents the recombination of two hard prongs if their combined jet mass is substantially larger than the masses of the separate prongs. The idea of collecting jets in "buckets" is also used. As an example, we consider the fully hadronic final state of pair-produced vectorlike top partners at the LHC, $pp\to T\bar{T}\to t\bar{t}HH$, and show that the new approach works better than the corresponding generalized $k_T$ jet clustering algorithm. We also show that tagging and kinematic reconstruction of boosted top quarks and Higgs bosons are possible with good quality even in these very busy final states. The vectorlike top partners are kinematically reconstructed, which allows their direct mass measurement.

Naturalness in the dark at the LHC

We revisit the Twin Higgs scenario as a “dark” solution to the little hierarchy problem, identify the structure of a minimal model and its viable parameter space, and analyze its collider implications. In this model, dark naturalness generally leads to Hidden Valley phenomenology. The twin particles, including the top partner, are all Standard-Model-neutral, but naturalness favors the existence of twin strong interactions — an asymptotically-free force that confines not far above the Standard Model QCD scale — and a Higgs portal interaction. We show that, taken together, these typically give rise to exotic decays of the Higgs to twin hadrons. Across a substantial portion of the parameter space, certain twin hadrons have visible and often displaced decays, providing a potentially striking LHC signature. We briefly discuss appropriate experimental search strategies.