We present the dominant two-loop electroweak corrections to the partial decay widths to gluon jets and prompt photons of the neutral CP-odd Higgs boson A^0, with mass M_{A^0} < 2 M_W, in the two-Higgs-doublet model for low to intermediate values of the ratio tan(beta) = v_2/v_1 of the vacuum expectation values. They apply as they stand to the production cross sections in hadronic and two-photon collisions, at the Tevatron, the LHC, and a future photon collider. The appearance of three gamma_5 matrices in closed fermion loops requires special care in the dimensional regularization of ultraviolet divergences. The corrections are negative and amount to several percent, so that they fully compensate or partly screen the enhancement due to QCD corrections.
We present the first calculation of the next-to-leading-order electroweak corrections to W-boson + jet hadroproduction including leptonic W-boson decays. The W-boson resonance is treated consistently using the complex-mass scheme, and all off-shell effects are taken into account. The corresponding next-to-leading-order QCD corrections have also been recalculated. All the results are implemented in a flexible Monte Carlo code. Numerical results for cross sections and distributions of this Standard Model benchmark process are presented for the Tevatron and the LHC.
This talk summarizes the first calculation of the next-to-leading-order electroweak corrections to W-boson + jet hadroproduction including leptonic W-boson decays [1]. The W-boson resonance is treated consistently using the complex-mass scheme, and all off-shell effects are taken into account. The corresponding next-to-leading-order QCD corrections have also been recalculated. All the results are implemented in a flexible Monte Carlo code. Selected numerical results for this Standard Model benchmark process are presented for the LHC.
We study the resummation of singular distributions for electroweak-boson production at large transverse momentum in hadronic collisions. We describe the factorization properties of the cross section near partonic threshold and construct the resummed cross section at next-to-leading logarithmic accuracy in moment space in terms of soft gluon anomalous dimensions. We present full analytical results for the expansion of the resummed cross section up to next-to-next-to-leading order. Our results can be applied to W, Z, and virtual gamma production at hadron colliders.
The high accuracy envisaged for future measurements of W-boson production at hadron colliders has to be matched by precise theoretical predictions. We study the impact of electroweak radiative corrections on W-boson production cross sections and differential distributions at the Tevatron and at the LHC. In particular, we include photon-induced processes, which contribute at O(alpha), and leading radiative corrections beyond O(alpha) in the high-energy Sudakov regime and from multi-photon final-state radiation. We furthermore present the calculation of the complete supersymmetric next-to-leadin…
If studies of electroweak gauge boson final states at the Large Hadron Collider, for Standard Model physics and beyond, are sensitive to effects of the initial state's transverse momentum distribution, appropriate generalizations of QCD shower evolution are required. We propose a method to do this based on QCD transverse momentum dependent (TMD) factorization at high energy. The method incorporates experimental information from the high-precision deep inelastic scattering (DIS) measurements, and includes experimental and theoretical uncertainties on TMD parton density functions. We illustrate …
We compute the contribution of order $α_S^2α^2$ to the cross section of a top-antitop pair in association with at least one heavy Standard Model boson -- $Z$, $W^\pm$, and Higgs -- by including all effects of QCD, QED, and weak origin and by working in the automated MadGraph5_aMC@NLO framework. This next-to-leading order contribution is then combined with that of order $α_S^3α$, and with the two dominant lowest-order ones, $α_S^2α$ and $α_Sα^2$, to obtain phenomenological results relevant to a 8, 13, and 100~TeV $pp$ collider.
We calculate the full one-loop electroweak radiative corrections, of ${\cal O}(α^2α_s)$, to the cross section of single $Z$-boson inclusive hadroproduction at finite transverse momentum ($p_T$). This includes the ${\cal O}(α)$ corrections to $Z+j$ production, the ${\cal O}(α_s)$ corrections to $Z+γ$ production, and certain QCD-electroweak interference contributions involving a single quark trace. We recover the QCD and purely weak corrections and study the QED corrections and the QCD-electroweak interference contributions for the first time. We also consider direct and resolved photoproduction…
We calculate the full one-loop electroweak radiative corrections to the cross section of single W-boson inclusive hadroproduction at finite transverse momentum (p_T). This includes the O(alpha) corrections to W+j production, the O(alpha_s) corrections to W+gamma production, and the tree-level contribution from W+j photoproduction with one direct or resolved photon in the initial state. We present the integrated cross section as a function of a minimum-p_T cut as well as the p_T distribution for the experimental conditions at the Fermilab Tevatron and the CERN LHC and estimate the theoretical u…
We present a new Monte Carlo event generator for the hadronic production of four top quarks in the POWHEG BOX framework. Besides the dominant next-to-leading order QCD corrections at $\mathcal{O}(α_s^5)$ we also include all subleading electroweak productions channels at leading-order accuracy. We validate our theoretical predictions by comparing to parton-shower matched predictions obtained within the MC@NLO framework for stable top quarks. Furthermore, we investigate in detail the various sources of theoretical uncertainties. Finally, we investigate a single lepton plus jets signature to stud…
We present a new approach for the prompt production of quarkonia which is based on the $k_T$-factorization method. The production of even C-parity quarkonia proceeds via the fusion of two (off-shell) gluons. Especially in the kinematics of the LHCb experiment these processes are thus expected to be a sensitive probe of the small-$x$ gluon distribution. We calculate the relevant off-shell matrix elements in terms of the light-front wave functions of the quarkonium states. We present our results for scalar and pseudoscalar charmonia and discuss photon transition form factors as well as cross sec…
We study the production of jets in hadronic collisions, by computing all contributions proportional to $α_S^nα^m$, with $n+m=2$ and $n+m=3$. These correspond to leading and next-to-leading order results, respectively, for single-inclusive and dijet observables in a perturbative expansion that includes both QCD and electroweak effects. We discuss issues relevant to the definition of hadronic jets in the context of electroweak corrections, and present sample phenomenological predictions for the 13-TeV LHC. We find that both the leading and next-to-leading order contributions largely respect the …
We extend and improve upon our previous calculation of electroweak top-quark pair hadroproduction in extensions of the Standard Model with extra heavy neutral and charged spin-1 resonances. In particular, we allow for flavour-non-diagonal $Z'$ couplings and take into account non-resonant production in the SM and beyond including the contributions with $t$-channel $W$ and $W'$ bosons. All amplitudes are generated using the Recola2 package. As in our previous work, we include NLO QCD corrections and consistently match to parton showers with the POWHEG method fully taking into account the interfe…
We implement non-minimal flavour violation (NMFV) in the MSSM at low scale. In this framework, we propose benchmark points for the mSUGRA scenario including non-minimal flavour violation by evaluating a number of experimental low-energy, electroweak precision and cosmological constraints. We finally discuss phenomenological aspects of our NMFV scenario and present a numerical analysis of squark and gaugino production cross sections at the LHC.
We present a new program (iHixs) which computes the inclusive Higgs boson cross-section at hadron colliders. It incorporates QCD corrections through NNLO, real and virtual electroweak corrections, mixed QCD-electroweak corrections, quark-mass effects through NLO in QCD, and finite width effects for the Higgs boson and heavy quarks. iHixs can be used to obtain the most precise cross-section values in fixed order perturbation theory in the Standard Model. In addition, it allows for a consistent evaluation of the cross-section in modified Higgs boson sectors with anomalous Yukawa and electroweak …
We investigate the electroweak form factors and semileptonic decay rates of pseudoscalar and vector mesons using the light-front constituent quark model. Our method of analytic continuation in the Drell-Yan-West (q^+=q^0+q^3=0) frame to obtain the weak form factors avoids the difficulty associated with the contributions from the nonvalence quark-antiquark pair creation. This method seems to provide a promising step forward to handle the exclusive processes in the timelike region. Our calculation reveals that the zero mode contribution is crucial to obtaining the correct values of the light-fro…
We analyze and compute, within a number of standard model (SM) extensions, the cross sections $σ_{A\to VV'}$ for the production of a heavy neutral pseudoscalar Higgs boson/spin-zero resonance at the LHC and its subsequent decays into electroweak gauge bosons. For comparison we calculate also the corresponding cross sections for a heavy scalar. The SM extensions we consider include a type-II two-Higgs doublet model (2HDM), a 2HDM with 4 chiral fermion generations, the minimal supersymmetric extension of the SM (MSSM), and top-color assisted technicolour models. Presently available phenomenologi…
This work studies the associated production of a top-quark pair with a $W$, $Z$, or Higgs boson at the LHC. Predictions for the total cross sections as well as for several differential distributions of the massive particles in the final state are provided. These predictions, valid for the LHC operating at $13$ TeV, include without any approximation all the NLO electroweak and QCD contributions of $\mathcal{O}(α_s^{i} α^{j+1})$ with $i+j=2,3$. In addition, the predictions presented here improve upon the NLO QCD results by adding the effects of soft gluon emission corrections resummed to next-to…
We study the effects of electroweak penguin (EWP) amplitudes in $B$ meson decays into two charmless pseudoscalars in the approximation of retaining only the dominant EWP operators $Q_9$ and $Q_{10}$. Using flavor SU(3) symmetry, we derive a set of model-independent relations between EWP contributions and tree-level decay amplitudes one of which was noted recently by Neubert and Rosner. Two new applications of these relations are demonstrated in which uncertainties due to EWP corrections are eliminated in order to determine a weak phase. Whereas the weak angle $α$ can be obtained from $B\toππ$ …
Motivated by excess diphoton events reported by ATLAS and CMS, we show that composite pseudoscalars, bound states of heavy fermions under a new confining gauge theory, can be pair-produced by Drell-Yan production if the constituent particles are electrically charged. The decays of these pion-like bound states into two photons can explain the observed events near 750 GeV. The model predicts that there should be significant numbers of 4-photon events from decays of the pseudoscalar pairs, as well as same-sign dilepton pairs at a somewhat lower invariant mass, or multijet signals, coming from dec…
We present an extensive analysis of squark and gaugino hadroproduction and decays in non-minimal flavour violating supersymmetry. We employ the so-called super-CKM basis to define the possible misalignment of quark and squark rotations, and we use generalized (possibly complex) charges to define the mutual couplings of (s)quarks and gauge bosons/gauginos. The cross sections for all squark-(anti-)squark/gaugino pair and squark-gaugino associated production processes as well as their decay widths are then given in compact analytic form. For four different constrained supersymmetry breaking model…
In models with extended Higgs sectors, it is possible that the Higgs boson discovered at the LHC is not the lightest one. We show that in a realistic model (the Type I 2-Higgs Doublet Model), when the sum of the masses of a light scalar and a pseudoscalar ($h$ and $A$) is smaller than the $Z$ boson mass, the Electroweak (EW) production of an $hA$ pair can dominate over QCD production by orders of magnitude, a fact not previously highlighted. This is because in the $gg$-initiated process, $hA$ production via a resonant $Z$ in the $s$-channel is prohibited according to the Landau-Yang theorem, w…
The high momentum components generated in the wave function of pseudoscalar mes* by the one-gluon-exchange interaction are investigated within a relativistic constituent quark model. Adopting the light-cone formalism, the sensitivity of the weak decay constant and the charge form factor to hard constituent quarks is illustrated.
In this talk I present the total cross sections, accurate at the NLO in QCD, for rare Standard-Model hadroproduction processes involving multi-Higgs-boson, multi-electroweak-boson and multi-top-quark final states. The comparison between cross sections at the LHC and at a future circular hadronic collider with up to 100 TeV centre-of-mass energy is detailed. Results relevant to the hadronic production of five electroweak bosons, and of a top-antitop pair in association with an electroweak vector boson and two jets are presented here for the first time with NLO accuracy.
I study phenomenological aspects of the SU(2)L x U(1) electroweak physics of a Higgs boson transforming like a quark-antiquark pair. A correspondence is established between its flavour content, the hierarchy of quark condensates, and the leptonic decay constants f of pseudoscalar mesons; the Higgs-mesons couplings coming from the symmetry-breaking scalar potential can then be expressed in terms of the f's, of the Cabibbo-Kobayashi-Maskawa mixing angles, and of the mass of the Higgs boson. Application is made to the decays of a Z boson into two leptons and two charged pseudoscalar mesons, more …
Following recent work on the combination of electroweak and strong radiative corrections to single W-boson hadroproduction in the POWHEG BOX framework, we generalize the above treatment to cover the neutral current Drell-Yan process. According to the POWHEG method, we combine both the next-to-leading order (NLO) electroweak and QED multiple photon corrections with the native NLO and Parton Shower QCD contributions. We show comparisons with the predictions of the electroweak generator HORACE, to validate the reliability and accuracy of the approach. We also present phenomenological results obta…
In model independent way we consider the possibility of the existence of fermion-antifermion, fermion-fermion bound states which appear due to $γ, Z^0(W^{\pm}$-bosons and scalar, pseudoscalars exchanges including radiative corrections. Our consideration includes the case where at least one particle in the bound state is Majorana fermion or scalar.This paper considers various types of bound states of particles contained in various extensions of the Glashow-Weinberg -Salam model. We calculate long-range forces induced by photonic, gluonic and fermionic loop corrections in scalar (pseudoscalar) e…
The first calculation of the next-to-leading-order electroweak corrections to Z-boson + jet hadroproduction including leptonic Z-boson decays is presented, i.e. to the production of a charged lepton--anti-lepton final state in association with one hard jet at the LHC and the Tevatron. The Z-boson resonance is treated consistently using the complex-mass scheme, and all off-shell effects as well as the contributions of the intermediate photon are taken into account. The corresponding next-to-leading-order QCD corrections have also been recalculated. The full calculation is implemented in a flexi…
If, in addition to the standard model fields, a new pseudoscalar field exists and couples to hypercharge topological number density, it can exponentially amplify hyperelectric and hypermagnetic fields in the symmetric phase of the electroweak plasma, while coherently rolling or oscillating. We present the equations describing the coupled system of a pseudoscalar field and hypercharge electromagnetic fields in the electroweak plasma at temperatures above the electroweak phase transition, discuss approximations to the equations, and their validity. We then solve the approximate equations using a…
The neutral component of a real pseudoscalar electroweak (EW) triplet can produce a diphoton excess at 750 GeV, if it is somewhat mixed with an EW singlet pseudoscalar. This triplet-singlet mixing allows for greater freedom in the diboson branching ratios than the singlet-only case, but it is still possible to probe the parameter space extensively with 300 fb$^{-1}$. The charged component of the triplet is pair-produced at the LHC, which results in a striking signal in the form of a pair of $Wγ$ resonances with an irreducible rate of 0.27 fb. Other signatures include multiboson final states fr…
Models of electroweak symmetry breaking with more than a single doublet of Higgs scalars contain a neutral pseudoscalar boson. The production of such a pseudoscalar in hadron collisions proceeds primarily via gluon fusion through a top-quark loop (except for those models in which the pseudoscalar coupling to bottom quarks is strongly enhanced). We compute the QCD corrections to this process in the heavy-quark limit, using an effective Lagrangian derived from the axial anomaly.
Condensates of colored fermions driving electroweak symmetry breaking could give rise to a light pseudoscalar that would show up in the Higgs search at the LHC. The branching ratios of its decay will distinguish it from the Higgs and illuminate its origin. In particular the colored fermions may be the techniquarks of a one family technicolor theory or the quarks of a strongly interacting fourth family. The former has more difficulties in this context.
We study the electroweak baryogenesis in a fermionic dark matter scenario with a (pseudo)scalar being the mediator in the Higgs portal. It is discussed that the electroweak phase transition turns to be first-order after taking into account the role of the (pseudo)scalar in the thermal effective potential in our extended standard model. Imposing the relic density constraint from the WMAP/Planck and the bounds from the direct detection experiments XENON100/LUX, we show that the dark matter scenario with a scalar mediator is hardly capable of explaining the baryogenesis while the same model with …
In this talk we discuss the next-to-leading-order electroweak (EW) corrections to W-boson + jet hadroproduction [1] and compare the full result to a simple approximation assuming factorization of EW and QCD corrections for the charged-current Drell-Yan process. The W-boson resonance is treated consistently using the complex-mass scheme, and all off-shell effects are taken into account. The corresponding next-to-leading-order QCD corrections have also been recalculated. All the results are implemented in a flexible Monte Carlo code. Selected numerical results for this Standard Model benchmark p…
We discuss the full electroweak one-loop corrections to the decay of the pseudoscalar Higgs boson A^0 into two sfermions within the Minimal Supersymmetric Standard Model. In particular, we consider the sfermions of the third generation, stops, sbottoms, and staus, including the left-right mixing. The electroweak corrections can go up to ~15% and can therefore not be neglected.
K -> Pi Pi decays are investigated in the framework of the SU(2)left x U(1) gauge theory of J=0 mesons proposed in ref.[1], to which is added an interaction between mesons respecting the two symmetries generally attributed to strong interactions, flavour symmetry and parity conservation. It is shown that the damping of the K+ -> Pi+ Pi0 amplitude with respect to the ones of Kshort -> Pi Pi results from a cancelation between the W and Z gauge bosons. The ratio of the two types of amplitudes is sensitive to the spectrum of electroweak (pseudoscalar and scalar) mass eigenstates, an in particular …
We calculate the dominant contributions to the muon $g-2$ at the two-loop level due to a generic pseudoscalar boson that may exist in any exotic Higgs sector in most extensions of the standard model. The leading effect comes from diagrams of the Barr-Zee type. A sufficiently light pseudoscalar Higgs boson can give rise to contribution as large as the electroweak contribution which is measurable in the next round of $g-2$ experiment. Through the contribution we calculated here, the anticipated improved data in the recent future on the muon $g-2$ can put the best limit on the possible existence …
After developing in ref.[1] a SU(2)left x U(1) gauge theory for J=0 mesons, I show in the case of two generations that: - the electroweak mass eigenstates differ, especially in the K and D sector, from what they are assumed to be on the basis of a classification by the SU(4) group of flavour; - a new mechanism for CP violation springs out, different from that of the standard model for quarks which requires at least three generations, and I construct a SU(2)left x U(1) gauge invariant Lagrangian which is not invariant by CP.
Electroweak radiative corrections to muon capture on nuclei are computed and found to be sizable. They enhance the capture rates for hydrogen and helium by 2.8% and 3.0% respectively. As a result, the value of the induced pseudoscalar coupling, g_P^exp, extracted from a recent hydrogen 1S singlet capture experiment is increased by about 21% to g_P^exp = 7.3 +/- 1.2 and brought into good agreement with the prediction of chiral perturbation theory, g_P^theory=8.2 +/- 0.2. Implications for helium capture rate predictions are also discussed.
We discuss the possible symmetries of the effective lagrangian describing interacting pseudoscalar-, vector-, and axial-vector mesons. Specific choices of the parameters give rise to an $[SU(2)\otimes SU(2)]^3$ symmetry. This symmetry can be obtained either {\it á la} Georgi, with all states in the spectrum remaining massless, or in a new realization, implying decoupling of the pseudoscalar bosons from degenerate vector and axial-vector mesons. This second possibility, when minimally coupled with $SU(2)\otimes U(1)$ electroweak gauge vector bosons, seems particularly appealing. All deviations …
We calculate the complete-NLO predictions for $t\bar{t}W^{\pm}$ and $t\bar{t}t\bar{t}$ production in proton--proton collisions at 13 and 100 TeV. All the non-vanishing contributions of $\mathcal{O}(α_s^i α^j)$ with $i+j=3,4$ for $t\bar{t}W^{\pm}$ and $i+j=4,5$ for $t\bar{t}t\bar{t}$ are evaluated without any approximation. For $t\bar{t}W^{\pm}$ we find that, due to the presence of $tW \to tW$ scattering, at 13(100) TeV the $\mathcal{O}(α_s α^3)$ contribution is about 12(70)\% of the LO, i.e., it is larger than the so-called NLO EW corrections (the $\mathcal{O}(α_s^2 α^2)$ terms) and has opposi…
We present a fully consistent implementation of electroweak and strong radiative corrections to single W hadroproduction in the POWHEG BOX framework, treating soft and collinear photon emissions on the same ground as coloured parton emissions. This framework can be easily extended to more complex electroweak processes. We describe how next-to-leading order (NLO) electroweak corrections are combined with the NLO QCD calculation, and show how they are interfaced to QCD and QED shower Monte Carlo. The resulting tool fills a gap in the literature and allows to study comprehensively the interplay o…
Little Higgs models have an enlarged global symmetry which makes the Higgs boson a pseudo-Goldstone boson. This symmetry typically contains spontaneously broken U(1) subgroups which provide light electroweak-singlet pseudoscalars. Unless such particles are absorbed as the longitudinal component of $Z'$ states, they appear as pseudoscalars in the physical spectrum at the electroweak scale. We outline their significant impact on Little Higgs phenomenology and analyze a few possible signatures at the LHC and other future colliders in detail. In particular, their presence significantly affects the…
Many models of electroweak symmetry breaking have an additional light pseudoscalar. If the Higgs boson can decay to a new pseudoscalar, LEP searches for the Higgs can be significantly altered and the Higgs can be as light as 86 GeV. Discovering the Higgs boson in these models is challenging when the pseudoscalar is lighter than 10 GeV because it decays dominantly into tau leptons. In this paper, we discuss discovering the Higgs in a subdominant decay mode where one of the pseudoscalars decays to a pair of muons. This search allows for potential discovery of a cascade-decaying Higgs boson with …
New interactions with Lorentz scalar structure, arising from physics beyond the standard model of electroweak interactions, will induce effective pseudoscalar interactions after renormalization by weak interaction loop corrections. Such induced pseudoscalar interactions are strongly constrained by data on $π^\pm \to l^\pm ν_l$ decay. These limits on induced pseudoscalar interactions imply limits on the underlying fundamental scalar interactions that in many cases are substantially stronger than limits on scalar interactions from direct Beta-decay searches.
The masses, pseudoscalar and vector weak decay constants and electromagnetic form factors of light S-wave mesons are studied in the framework of the relativistic quark model based on the quasipotential approach. We use the same model assumptions and parameters as in our previous investigations of heavy meson and baryon properties. The masses and wave functions of the ground state and radially excited pi, rho, K, K* and phi mesons, obtained by solving numerically the relativistic Schroedinger-like equation with the complete relativistic q bar q potential including both spin-independent and spin…
A general analysis for B decays to two pseudoscalars, involving ten modes, is presented. A simple model for final state interactions and rescattering effects is proposed. We show how the data can be used to deduce important information on electroweak penguins (EWP), rescattering and color suppression effects and on the CKM parameters in a largely model independent way by using chisquared-minimization. We find that the current data suggests the presence of color-suppressed tree at levels somewhat larger than simple theoretical estimates. Once the data improves the extraction of alpha and/or gam…
The scalar composite representations of the electroweak symmetry group of the Standard Model are exhibited in the case of two generations of quarks. The link between `strong' and `electroweak' eigenstates is investigated, showing that the quark content commonly attributed to pseudoscalar mesons needs to be modified. After doing so, the mechanism suppressing the decays K{+} into Pi{+} Pi{0} with respect to K{short} into Pi{+} Pi{-} is unraveled, without reference to any model of quark spectator or `factorization' hypothesis. The same mechanism is shown to suppress the decays K{long} into two pi…
Electroweak penguin (EWP) amplitudes are studied model-independently in $B$ meson decays to charmless final states consisting of a vector meson ($V$) and a pseudoscalar meson ($P$). A set of SU(3) relations is derived between EWP contributions and tree amplitudes, in the approximation of retaining only the dominant EWP operators $Q_9$ and $Q_{10}$ . Two applications are described for constraining the weak phase $γ$, in $B^{\pm}\to ρ^{\pm} K^0$ and $B^{\pm}\to ρ^0 K^{\pm}$ (or $B^{\pm}\to K^{*\pm}π^0$ and $B^{\pm}\to K^{*0}π^{\pm}$), and in $B^0\to K^{*\pm}π^{\mp}$ and $B^{\pm}\toϕK^{\pm}$. The…
The Minimal supersymmetric extension of the Standard Model (MSSM) with light stops, charginos or pseudoscalar Higgs bosons has been suggested as an explanation of the too high value of the branching ratio of the Z0 boson into b quarks (Rb anomaly). A program including all radiative corrections to the MSSM at the same level as the radiative corrections to the SM has been developed and used to perform global fits to all electroweak data from LEP, SLC and the Tevatron. The probability of the global fit improves from 8% in the SM to 18% in the MSSM. Including the b->s gamma rate, as measured by CL…
The current status of electroweak radiative corrections to the muon anomalous magnetic moment is discussed. Asymptotic expansions for some important electroweak two loop top quark triangle diagrams are illustrated and extended to higher order. Results are compared with the more general integral representation solution for generic fermion triangle loops coupled to pseudoscalar and scalar bosons of arbitrary mass. Excellent agreement is found for a broader than expected range of mass parameters.
Building upon the formulation of transverse-momentum resummation for heavy-quark hadroproduction, we present the first application of the $q_T$ subtraction formalism to the computation of electroweak corrections to massive lepton pairs through the Drell-Yan mechanism. We then study the power suppressed contributions to the $q_T$ subtraction formula in the parameter $r_{cut}$, defined as the minimum transverse momentum of the lepton pair normalised to its invariant mass. We analytically compute the leading power correction from initial and final-state radiation to the inclusive cross section. I…
We address the computation of Γ_Z and of the intriguing quantity R_b in the MSSM including full treatment of the Higgs sector. For a pseudoscalar Higgs mass m_{A^0}>70\,GeV and CDF limits on m_t, the bounds on R_b at 1σlevel leave no room to the MSSM to solve the `R_b crisis' for any combination of the parameters, not even admitting the possibility of a light chargino and a light stop of O(50) GeV; however, for m_t not restricted by CDF, a `tangential' solution exists in the window 2<\tanβ<10 with a light chargino and stop. In contrast, for a pseudoscalar mass 40\,GeV<m_{A^0}<60\,GeV and CDF l…
We discuss the role of electroweak penguins in $B$ decays to two light pseudoscalar mesons. We confirm that the extraction of the weak phase $α$ through the isospin analysis involving $B\toππ$ decays is largely unaffected by such operators. However, the methods proposed to obtain weak and strong phases by relating $B\toππ$, $B\toπK$ and $B\to KK$ decays through flavor SU(3) will be invalidated if electroweak penguins are large. We show that, although the introduction of electroweak penguin contributions introduces no new amplitudes of flavor SU(3), there are a number of ways to experimentally …
Using two suitable benchmark scenarios that satisfy the experimental constraints on the total decay width of the $125 \, {\rm GeV}$ Higgs boson, we determine the bounds on light CP-odd spin-0 states in the 2HDM+$a$ model that arise from existing LHC searches. Our work represents the first thorough study that considers the parameter space with $m_a \lesssim 100 \, {\rm GeV}$ and should prove useful for 2HDM+$a$ interpretations of future ATLAS, CMS and LHCb searches for pseudoscalars with masses below the electroweak scale.
One of the main features of a Two-Higgs Doublet Model (2HDM) is the presence of two additional neutral Higgs states, besides the one mimicking the ~125 GeV state observed at the LHC. The three Higgs bosons of a 2HDM can be produced at the LHC either singly via gluon fusion or in pairs with each other. When analyzing their pair production, the emphasis is laid on gluon-initiated processes, and the electroweak (EW) production is generally not treated on the same footing, assuming its contribution to be highly subleading. We show here that when the sum of the masses of the lightest scalar and pse…
As described previously, in SU(5) gauge theory with massless left-handed $ {\bf 5 \oplus 15 \oplus 40 \oplus 45^*}$ fermions \{QUD\}, an S-Matrix is produced by infra-red anomaly dynamics that might provide an extraordinarily economic origin and unification for the Standard Model. All particles are bound-states, with dynamically generated masses, and there is no Higgs sector. In this paper, the radically different dynamical role played by the top quark is elaborated. It does not reproduce Standard Model "$ t\bar{t} $" events but, instead, these events are reproduced by the multiple vector boso…
