Tevong You

article

Hadron collider sensitivity to fat flavourful Z^′s for R K ∗ $$ {R}_{K^{\left(\ast \right)}} $$

B. C. Allanach, Tyler Corbett, Matthew J. Dolan, Tevong You

Journal of High Energy Physics > 2019 > 2019 > 3 > 1-24

Abstract We further investigate the case where new physics in the form of a massive Z^′ particle explains apparent measurements of lepton flavour non-universality in B → K⁽*⁾l⁺l⁻ decays. Hadron collider sensitivities for direct production of such Z^′s have been previously studied in the narrow width limit for a μ⁺μ⁻ final state. Here, we extend the analysis to sizeable decay widths and improve the...

article

Updated global SMEFT fit to Higgs, diboson and electroweak data

John Ellis, Christopher W. Murphy, Verónica Sanz, Tevong You

Journal of High Energy Physics > 2018 > 2018 > 6 > 1-34

Abstract The ATLAS and CMS collaborations have recently released significant new data on Higgs and diboson production in LHC Run 2. Measurements of Higgs properties have improved in many channels, while kinematic information for h → γγ and h → ZZ can now be more accurately incorporated in fits using the STXS method, and W⁺W⁻ diboson production at high p_T gives new sensitivity to deviations from the...

article

The case for future hadron colliders from B → K^(*)μ⁺μ⁻ decays

B. C. Allanach, Ben Gripaios, Tevong You

Journal of High Energy Physics > 2018 > 2018 > 3 > 1-26

Abstract Recent measurements in B → K^(*)μ⁺μ⁻ decays are somewhat discrepant with Standard Model predictions. They may be harbingers of new physics at an energy scale potentially accessible to direct discovery. We estimate the sensitivity of future hadron colliders to the possible new particles that may be responsible for the anomalies at tree-level: leptoquarks or Z′s. We consider luminosity upgrades...

article

Extending the Universal One-Loop Effective Action: heavy-light coefficients

Sebastian A. R. Ellis, Jérémie Quevillon, Tevong You, Zhengkang Zhang

Journal of High Energy Physics > 2017 > 2017 > 8 > 1-22

Abstract The Universal One-Loop Effective Action (UOLEA) is a general expression for the effective action obtained by evaluating in a model-independent way the one-loop expansion of a functional path integral. It can be used to match UV theories to their low-energy EFTs more efficiently by avoiding redundant steps in the application of functional methods, simplifying the process of obtaining Wilson...

article

Dimension-6 operator analysis of the CLIC sensitivity to new physics

John Ellis, Philipp Roloff, Verónica Sanz, Tevong You

Journal of High Energy Physics > 2017 > 2017 > 5 > 1-22

Abstract We estimate the possible accuracies of measurements at the proposed CLIC e⁺e⁻ collider of Higgs and W⁺W⁻ production at centre-of-mass energies up to 3 TeV, incorporating also Higgsstrahlung projections at higher energies that had not been consid-ered previously, and use them to explore the prospective CLIC sensitivities to decoupled new physics. We present the resulting constraints on the...

article

On the structure of anomalous composite Higgs models

Ben Gripaios, Marco Nardecchia, Tevong You

The European Physical Journal C > 2017 > 77 > 1 > 1-14

We describe the anomaly structure of a composite Higgs model in which the SO(5) / SO(4) coset structure of the minimal model is extended by an additional, non-linearly realised $$U(1)_{\eta }$$ U ( 1 ) η . In addition, we show that the effective Lagrangian admits a term that, like the Wess–Zumino–Witten term in the chiral Lagrangian for QCD, is not invariant under the non-linearly realised...

article

Mixed heavy–light matching in the Universal One-Loop Effective Action

Sebastian A.R. Ellis, Jérémie Quevillon, Tevong You, Zhengkang Zhang

Physics Letters B > 2016 > 762 > C > 166-176

Recently, a general result for evaluating the path integral at one loop was obtained in the form of the Universal One-Loop Effective Action. It may be used to derive effective field theory operators of dimensions up to six, by evaluating the traces of matrices in this expression, with the mass dependence encapsulated in the universal coefficients. Here we show that it can account for loops of mixed...

article

The price of an electroweak monopole

John Ellis, Nick E. Mavromatos, Tevong You

Physics Letters B > 2016 > 756 > C > 29-35

In a recent paper, Cho, Kim and Yoon (CKY) have proposed a version of the SU(2)×U(1) Standard Model with finite-energy monopole and dyon solutions. The CKY model postulates that the effective U(1) gauge coupling →∞ very rapidly as the Englert–Brout–Higgs vacuum expectation value →0, but in a way that is incompatible with LHC measurements of the Higgs boson H→γγ decay rate. We construct generalisations...

article

Sensitivities of prospective future e ⁺ e ⁻ colliders to decoupled new physics

John Ellis, Tevong You

Journal of High Energy Physics > 2016 > 2016 > 3 > 1-19

Abstract We explore the indirect sensitivities to decoupled new physics of prospective precision electroweak measurements, triple-gauge-coupling measurements and Higgs physics at future e ⁺ e ⁻ colliders, with emphasis on the ILC250 and FCC-ee. The Standard Model effective field theory (SM EFT) is adopted as a model-independent approach for relating experimental precision...

article

On the interpretation of a possible ∼ 750 GeV particle decaying into γγ

John Ellis, Sebastian A.R. Ellis, Jérémie Quevillon, Verónica Sanz, more

Journal of High Energy Physics > 2016 > 2016 > 3 > 1-34

Abstract We consider interpretations of the recent ∼ 3σ reports by the CMS and ATLAS collaborations of a possible X (∼750 GeV) state decaying into γγ final states. We focus on the possibilities that this is a scalar or pseudoscalar electroweak isoscalar state produced by gluon-gluon fusion mediated by loops of heavy fermions. We consider several models for these fermions, including a single vector-like...

article

The universal one-loop effective action

Aleksandra Drozd, John Ellis, Jérémie Quevillon, Tevong You

Journal of High Energy Physics > 2016 > 2016 > 3 > 1-34

Abstract We present the universal one-loop effective action for all operators of dimension up to six obtained by integrating out massive, non-degenerate multiplets. Our general expression may be applied to loops of heavy fermions or bosons, and has been checked against partial results available in the literature. The broad applicability of this approach simplifies one-loop matching from an ultraviolet...

article

Comparing EFT and exact one-loop analyses of non-degenerate stops

Aleksandra Drozd, John Ellis, Jérémie Quevillon, Tevong You

Journal of High Energy Physics > 2015 > 2015 > 6 > 1-29

Abstract We develop a universal approach to the one-loop effective field theory (EFT) using the Covariant Derivative Expansion (CDE) method. We generalise previous results to include broader classes of UV models, showing how expressions previously obtained assuming degenerate heavy-particle masses can be extended to non-degenerate cases. We apply our method to the general MSSM with non-degenerate...

article

The effective Standard Model after LHC Run I

John Ellis, Verónica Sanz, Tevong You

Journal of High Energy Physics > 2015 > 2015 > 3 > 1-28

Abstract We treat the Standard Model as the low-energy limit of an effective field theory that incorporates higher-dimensional operators to capture the effects of decoupled new physics. We consider the constraints imposed on the coefficients of dimension-6 operators by electroweak precision tests (EWPTs), applying a framework for the effects of dimension- 6 operators on electroweak precision...

article

Complete Higgs sector constraints on dimension-6 operators

John Ellis, Verónica Sanz, Tevong You

Journal of High Energy Physics > 2014 > 2014 > 7 > 1-23

Abstract Constraints on the full set of Standard Model dimension-6 operators have previously used triple-gauge couplings to complement the constraints obtainable from Higgs signal strengths. Here we extend previous analyses of the Higgs sector constraints by including information from the associated production of Higgs and massive vector bosons (H+V production), which excludes a direction of limited...

article

Prima facie evidence against spin-two Higgs impostors

John Ellis, Verónica Sanz, Tevong You

Physics Letters B > 2013 > 726 > 1-3 > 244-250

The new particle X recently discovered by the ATLAS and CMS Collaborations is widely expected to have spin zero, but this remains to be determined. The leading alternative is that X has spin two, presumably with graviton-like couplings. We show that measurements of the X particle to pairs of vector bosons constrain such scenarios. In particular, a graviton-like Higgs impostor in scenarios with a warped...

article

Updated global analysis of Higgs couplings

John Ellis, Tevong You

Journal of High Energy Physics > 2013 > 2013 > 6 > 1-19

Abstract There are many indirect and direct experimental indications that the new particle H discovered by the ATLAS and CMS Collaborations has spin zero and (mostly) positive parity, and that its couplings to other particles are correlated with their masses. To a high degree of confidence, it is a Higgs boson, and here we examine the extent to which its couplings resemble those of the single Higgs...

article

Associated production evidence against Higgs impostors and anomalous couplings

John Ellis, Verónica Sanz, Tevong You

The European Physical Journal C > 2013 > 73 > 7 > 1-8

There is still no proof that the new particle X recently discovered by the ATLAS and CMS Collaborations indeed has spin zero and positive parity, as confidently expected. We show here that the energy dependence of associated W/Z+X production would be much less for a J ^P=0⁺ boson with minimal couplings, such as the Higgs boson of the Standard Model, than for a spin-two particle with graviton-like...

article

Distinguishing ‘Higgs’ spin hypotheses using γγ and WW ^∗ decays

John Ellis, Ricky Fok, Dae Sung Hwang, Verónica Sanz, more

The European Physical Journal C > 2013 > 73 > 7 > 1-15

The new particle X recently discovered by the ATLAS and CMS Collaborations in searches for the Higgs boson has been observed to decay into γγ, ZZ ^∗ and WW ^∗, but its spin and parity, J ^P, remain a mystery, with J ^P=0⁺ and 2⁺ being open possibilities. We use PYTHIA and Delphes to simulate an analysis of the angular distribution of gg→X→γγ decays in a full 2012 data set, including realistic background...

article

A fast track towards the ‘Higgs’ spin and parity

John Ellis, Dae Sung Hwang, Verónica Sanz, Tevong You

Journal of High Energy Physics > 2012 > 2012 > 11 > 1-17

Abstract The LHC experiments ATLAS and CMS have discovered a new boson that resembles the long-sought Higgs boson: it cannot have spin one, and has couplings to other particles that increase with their masses, but the spin and parity remain to be determined. We show here that the ‘Higgs’ + gauge boson invariant-mass distribution in ‘Higgs’-strahlung events at the Tevatron or the LHC would be very...

article

Global analysis of experimental constraints on a possible Higgs-like particle with mass ∼ 125 GeV

John Ellis, Tevong You

Journal of High Energy Physics > 2012 > 2012 > 6 > 1-21

Abstract We perform a global analysis of the constraints on a possible Higgs-like particle with mass ∼ 125 GeV that are provided by the ATLAS, CDF, CMS and D0 experiments. We combine the available constraints on possible deviations from the Standard Model Higgs couplings to massive vector bosons and to fermions, considering also the possibilities of non-standard loop-induced couplings to photon and...

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Search results for: Tevong You

Hadron collider sensitivity to fat flavourful Z^′s for R K ∗ $$ {R}_{K^{\left(\ast \right)}} $$

Updated global SMEFT fit to Higgs, diboson and electroweak data

The case for future hadron colliders from B → K^(*)μ⁺μ⁻ decays

Extending the Universal One-Loop Effective Action: heavy-light coefficients

Dimension-6 operator analysis of the CLIC sensitivity to new physics

On the structure of anomalous composite Higgs models

Mixed heavy–light matching in the Universal One-Loop Effective Action

The price of an electroweak monopole

Sensitivities of prospective future e ⁺ e ⁻ colliders to decoupled new physics

On the interpretation of a possible ∼ 750 GeV particle decaying into γγ

The universal one-loop effective action

Comparing EFT and exact one-loop analyses of non-degenerate stops

The effective Standard Model after LHC Run I

Complete Higgs sector constraints on dimension-6 operators

Prima facie evidence against spin-two Higgs impostors

Updated global analysis of Higgs couplings

Associated production evidence against Higgs impostors and anomalous couplings

Distinguishing ‘Higgs’ spin hypotheses using γγ and WW ^∗ decays

A fast track towards the ‘Higgs’ spin and parity

Global analysis of experimental constraints on a possible Higgs-like particle with mass ∼ 125 GeV

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