A crucial test of the Standard Model is the measurement of electroweak gauge-boson scattering. In this paper, we describe a generic parameterization aimed at a realistic simulation of weak-boson scattering at the LHC. The parameterization implements resonances of all possible spin and isospin combinations, properly matched to the low-energy effective (chiral) Lagrangian, includes leading higher-order effects and contains a minimal unitarization scheme. We implement the parameterization in the Monte-Carlo event generator WHIZARD and present results for complete partonic cross-section integration and event generation. We provide a comparison with the effective W approximation that previously has been used for most WW scattering studies at hadron colliders.
If the di-photon excess at 750 GeV hinted by the 2015 data at the LHC is explained in terms of a scalar resonance participating in the breaking of the electro-weak symmetry, this resonance must be accompanied by other scalar states for perturbative unitarity in vector boson scattering to be preserved. The simplest set-up consistent with perturbative unitarity and with the data of the di-photon excess is the Georgi-Machacek model.
If a new massive vector boson with nonzero axial couplings to fermions will be observed at LHC, then an upper limit on the scale of new physics could be derived from unitarity of $\mathcal{S}$-matrix. The new physics will involve either new massive fermions, or scalars, or even a strongly coupled sector. We derive a model independent bound on the scale of new physics. If $M_{G}/ g_{A} < 3$ TeV and the fermion is a top quark, the upper limit is 78 TeV.
We study the constraints implied by partial wave unitarity on new physics in the form of spin-zero di-boson resonances at LHC. We derive the scale where the effective description in terms of the SM supplemented by a single resonance is expected to break down depending on the resonance mass and signal cross-section. Likewise, we use unitarity arguments in order to set perturbativity bounds on renormalizable UV completions of the effective description. We finally discuss under which conditions scalar di-boson resonance signals can be accommodated within weakly-coupled models.
We analyze the scattering of fermions, Higgs and electroweak gauge bosons in order to obtain the partial-wave unitarity bounds on dimension-six effective operators, including those involving fermions. We also quantify whether, at the LHC energies, the dimension-six operators lead to unitarity violation after taking into account the presently available constraints on their Wilson coefficients. Our results show that for most dimension-six operators relevant for the LHC physics there is no unitarity violation at the LHC energies, and consequently, there is no need for the introduction of form fac…
Phenomena related to the non-perturbative aspects of strong interactions at the LHC are discussed with emphasis on elastic and inelastic soft and hard diffraction processes. Predictions for the global characteristics and angular distributions in proton-proton collisions with elastic and multiparticle final states are given. Potential for discovery of the novel effects related to the increasing role of the elastic scattering at the LHC energies and its physical implications in diffractive and multiparticle production processes are reviewed.
We present Next-to-Leading Order (NLO) predictions for $γγγγ$ final states, including the effects of photon fragmentation. Our results are calculated fully analytically using the techniques of $D$-dimensional unitarity, and we discuss some refinements to existing methods, focusing particularly on the role of three-mass triangle coefficients. Using these techniques we are able to produce a numerically stable Monto Carlo code that runs fully in double precision. We investigate the $4γ$ signal at colliders, both for Run II of the LHC and at future machines. Our results are implemented in MCFM.
We study the effects of two-body Higgs boson scattering by exchanging unpsrticles. The unparticle contribution can change the standard model prediction for two-body Higgs boson scattering partial wave amplitude significantly leading to modification of the unitarity constraint on the standard model Higgs boson mass. For unparticle dimension $d_\U$ between 1 and 2, the unitarity constraint on Higgs boson mass can be larger than that in the SM. Information on unparticle interaction can also be obtained.
We study the compatibility of the unitarity bound and the 8TeV LHC on the effective theory of the scalar dark matter. In several signals of effective interactions, mono-jet with missing energy events are studied. We found that, at least, if the dark matter mass is about 800GeV or heavier, contributions of events violating the unitarity are not negligible. The unitarity conditions in the 14TeV LHC are also calculated.
The quartic gauge boson couplings in the ${SU(3)}_C \otimes {SU(3)}_L \otimes {U(1)}_N$ models are presented. We find that the couplings of four {\it differrent} gauge bosons may have unusual Lorentz structure and the couplings sastify the tree unitarity requirement at high energy limit.
Introducing arbitrary number of neutral Higgs bosons in the electroweak symmetry breaking sector, we derive a set of conditions among Higgs couplings which need to be satisfied to maintain the unitarity of the high energy scattering amplitudes of weak gauge bosons at the tree level (unitarity sum rules). It is shown that the unitarity sum rules require the tree level $ρ$ parameter to be 1, without explicitly invoking the custodial symmetry arguments. The one-loop finiteness of the electroweak oblique corrections is automatically guaranteed once these unitarity sum rules are imposed among Higgs…
We study the observability of new interactions which modify Higgs-pair production via vector-boson fusion processes at the LHC and at future proton-proton colliders. In an effective-Lagrangian approach, we explore in particular the effect of the operator $h^2 W_{μν}^a W^{a,μν}$, which describes the interaction of the Higgs boson with transverse vector-boson polarization modes. By tagging highly boosted Higgs bosons in the final state, we determine projected bounds for the coefficient of this operator at the LHC and at a future 27 TeV or 100 TeV collider. Taking into account unitarity constrain…
We study perturbative unitarity and electroweak oblique corrections in the electroweak symmetry breaking models including an arbitrary number of neutral Higgs bosons. Requiring the perturbative unitarity of the high energy scattering amplitudes of weak gauge bosons and the neutral Higgs bosons at tree level, we obtain a set of conditions among the Higgs coupling strengths (unitarity sum rules). It is shown that the unitarity sum rules require the tree level rho parameter to be 1 if there are only neutral Higgs bosons. Moreover, we find that the one-loop finiteness of the electroweak oblique co…
Anticipating improved determinations of $m_t$, $|V_{cb}|$, $|V_{ub}/V_{cb}|$, $B_K$ and $F_B \sqrt{B_B}$ in the next five years we make an excursion into the future in order to find a possible picture of the unitarity triangle, of quark mixing and of CP violation around the year~2000. We then analyse what impact on this picture will result from the measurements of the four possibly cleanest quantities: $BR(K^+ \to π^+ ν\barν)$, $x_d/x_s$, $\sin(2α)$ and $\sin(2β)$. In the course of our investigations we extend the analysis of the unitarity triangle beyond the leading order in the Wolfenstein p…
We study the unitarity constraint on the two body Higgs boson elastic scattering in the presence of extra dimensions. The contributions from exchange of spin-2 and spin-0 Kaluza-Klein states can have large effect on the partial wave amplitude. Unitarity condition restrict the maximal allowed value for the ratio $r$ of the center of mass energy to the gravity scale to be less than one. Although the constraint on the standard Higgs boson mass for $r$ of order one is considerably relaxed, for small $r$ the constraint is similar to that in the Standard Model. The resulting bound on the Higgs boson…
Encouraged by a hint in a search for right-handed $W$ bosons at the LHC, we investigate whether the unitarity of a right-handed quark mixing matrix and the equality of the left- and right-handed quark mixing matrices could be tested at the LHC. We propose a particular test, involving counting the numbers of $b$-tags in the final state, and simulate the test at the event level with Monte-Carlo tools for the forthcoming $\sqrt{s}=13$ TeV LHC run. We find that testing unitarity with 20/fb will be challenging; our test successfully rejects unitarity if the right-handed quark mixing matrix is non-u…
The perturbative unitarity bound is studied in the monojet process at LHC. The production of the dark matter is described by the low-energy effective theory. The analysis of the dark matter signal is not validated, if the unitarity condition is violated. It is shown that the current LHC analysis the effective theory breaks down, at least, when the dark matter is lighter than O(100) GeV. Future prospects for $\sqrt{s}$ = 14 TeV are also discussed. The result is independent of physics in high energy scales.
Using asymptotic helicity amplitudes for Vector-Vector, Vector-Higgs and Higgs-Higgs scattering, we establish the unitarity constraints on the $SU(2)_c$ conserving and $W_μ$ depending interactions, which at sufficiently high energies may create strong forces among the transverse vector boson and Higgs states. We then derive upper bounds for the couplings of these interactions, which depend on the high energy scale where unitarity is saturated. If \eg\, unitarity is saturated at 1TeV, then $λ_W \lsim 0.12$ is obtained. The implied relations between the present and future LEP results, and the po…
If there is new physics associated with the top quark, it could show up as anomalous couplings of the top quark to weak gauge bosons, such as $Z\ttbar$ and $W\tbbar$ vector and axial-vector couplings. We use the processes $\ttbar\to Z^0Z^0$, $\ttbar\to W^+W^-$, and $\ttbar\to Z^0H$ to obtain the unitarity constraints on these anomalous couplings, and combine these constraints with those from precision electroweak data. The unitarity constraints can impose additional limits on the anomalous couplings when the scale of new physics is as low as 2 TeV. A nonzero measurement of such an anomalous co…
Effective Field Theory (EFT) extensions of the Standard Model are tools to compute observables $\big(e.g.$ cross sections with partonic center-of-mass energy $\sqrt{\hat{s}}\,\big)$ as a systematically improvable expansion suppressed by a new physics scale $M$. If one is interested in EFT predictions in the parameter space where $M<\sqrt{\hat{s}}$, concerns of self-consistency emerge, which can manifest as a violation of perturbative partial-wave unitarity. However, when we search for the effects of an EFT at a hadron collider with center-of-mass energy $\sqrt{s}$ using an inclusive strategy, …
The strong nature of Composite Higgs models manifests at high energies through the growing behavior of the scattering amplitudes of longitudinally polarized weak bosons that leads to the formation of composite resonances as well as non-resonant strong effects. In this work the unitarity of these scattering amplitudes is used as a tool to assess the profile of the composite spectrum of the theory, including non-resonant enhancements, vector resonances and the CP-even scalar excitation. These three signatures are then studied in realistic scattering processes at hadron colliders, aiming to estim…
We discuss the lineshape of a heavy Higgs boson, and the behaviour well above resonance. Previous studies concluded that the energy-dependent Higgs width should be used in the resonance region, but must not be used well away from it. We derive the full result and show that it smoothly extrapolates these limits. It is extremely simple, and would be straightforward to implement in existing calculations.
Taking into account the constraints from LEP1 and lower energy experiments, we identify the seven $SU(2)\times U(1)$ gauge invariant purely bosonic $dim=6$ operators which provide a quite general description of how New Physics could reflect in the bosonic world, if it happens that all new degrees of freedom are too heavy to be directly produced in the future colliders. Five of these operators are CP conserving and the remaining ones are CP violating. We derive the unitarity constraints for the CP violating operators and compare them with the already known constraints for the CP conserving ones…
We explore the possibility of a beyond the standard model scalar ($ϕ$) as a possible explanation of the diphoton resonance at 750~GeV invariant mass reported by the ATLAS and CMS collaborations at the large hadron collider (LHC). We first present in a model-independent way the scalar-gluon-gluon and scalar-photon-photon effective couplings needed for obtaining the required diphoton cross-section at the LHC for different total widths. We investigate here two new-physics possibilities that can generate these effective couplings, namely, (i) the 2-Higgs-doublet model (2HDM) in the alignment limit…
We study the effects on oscillations in the neutral-Kaon system from lepton and hadron self-energy loops in the W-boson propagators. The corresponding W box diagrams are evaluated by attaching the external quark lines to covariant vertex functions for the composite Kaons, integrating over all off-shell momenta. We find that the ratio of the imaginary and real parts of the amplitude is of the same size as with the experimental value of the modulus of the CP-violating parameter epsilon.
We analyze the tree-level 2->2 scattering of massive spin-2 bosons in a theory with only relevant and marginal operators and extract the sum rules on the coupling constants and masses required to achieve tree-level unitarity to very high energy. We do this for four illustrative cases. In the first, we include massive spin-1 and spin-0 bosons in our theory, but do not require gauge invariance. For this case, we find that it is, in fact, possible to construct a theory where all 2->2 scattering processes are tree-level unitary to very high energy. In the second case, we consider a theory that onl…
The critical values for the mass of the Higgs bosons, at which the theory becomes strongly interacting, are calculated using the equivalence theorem, at high energies this allows us to replace the longitudinally polarized gauge bosons in the $S$ matrix for the corresponding Goldstone bosons. An appropriate ansatz for defining the would-be Goldstone bosons in the case of an additional neutral current, beyond the minimal standard model, is also presented.
We obtain the partial-wave unitarity constraints on dimension-six operators stemming from the analyses of vector boson and Higgs scattering processes as well as the inelastic scattering of standard model fermions into electroweak gauge bosons. We take into account all coupled channels, all possible helicity amplitudes, and explore a six-dimensional parameter space of anomalous couplings. Our analysis shows that for those operators affecting the Higgs couplings, present 90% confidence level constraints from global data analysis of Higgs and electroweak data are such that unitarity is not violat…
Some years ago Appelquist and Chanowitz considered the scattering of fermion--anti-fermion into a pair of longitudinal gauge bosons. Their calculation established that unitarity implies that the physics giving mass to a quark of mass $m_f$ must be below a mass scale of $16 πv^2 / m_f$ ($v=246$ GeV). This bound is a bit difficult to interpret, because the unitarity of gauge boson scattering requires in any case that there be new physics, such as a Higgs boson, with a mass lighter than this. This paper re-examines the Appelquist-Chanowitz bound in order to clarify its meaning. This work uses toy…
We show that it is possible to accommodate the observed size of the phase in $B^0_s$--$\bar B^0_s$, mixing in the framework of a model with violation of $3\times 3$ unitarity. This violation is associated to the presence of a new $Q=2/3$ isosinglet quark $T$, which mixes both with $t$ and $c$ and has a mass not exceeding 500 GeV. The crucial point is the fact that this framework allows for $χ\equiv\arg(-V_{ts}V_{cb}V_{tb}^*V_{cs}^*)$ of order $λ$, to be contrasted with the situation in the Standard Model, where $χ$ is constrained to be of order $λ^2$. We point out that this scenario implies ra…
We investigate the importance of unitarity corrections to parton evolution in heavy flavor production at the LHC. The gluon distribution is determined with a fit to HERA data applying a unified BFKL-DGLAP approach, in which the non-linear evolution is described by the Balitsky-Kovchegov equation. First we estimate b anti-b production at CDF and D0. Then, cross sections for heavy quark production at various LHC experiments are estimated, tracing the impact of the unitarity corrections.
We compute the helicity amplitudes for boson-boson scattering at high energy due to the operators $Ø_{BΦ}$, $Ø_{WΦ}$ and $Ø_{UB}$, and we derive the corresponding unitarity bounds. Thus, we provide relations between the couplings of these operators and the corresponding New Physics thresholds, where either unitarity is saturated or new degrees of freedom are excited. We compare the results with those previously obtained for the operators $Ø_W$ and $Ø_{UW}$ and we discuss their implications for direct and indirect tests at present and future colliders. The present treatment completes the study …
The scalar field associated with fluctuations in the positions of the two branes, the ``radion'', plays an important role determining the cosmology and collider phenomenology of the Randall-Sundrum solution to the hierarchy problem. It is now well known that the radion mass is of order the weak scale, and that its couplings to standard model fields are order 1/TeV to the trace of the energy momentum tensor. We calculate longitudinal vector boson scattering amplitudes to explore the constraints on the radion mass and its coupling from perturbative unitarity. The scattering cross section can ind…
Interpretation of unitarity saturation as reflective scattering is discussed. Analogies with optics and Berry phase alongside with the experimental consequences of the proposed interpretation at the LHC energies are considered.
We study the perturbative unitarity bound given by dimension six derivative interactions consisting of Higgs doublets. These operators emerge from kinetic terms of composite Higgs models or integrating out heavy particles that interact with Higgs doublets. They lead to new phenomena beyond the Standard Model. One of characteristic contributions by derivative interactions appear in vector boson scattering processes. Longitudinal modes of massive vector bosons can be regarded as Nambu Goldstone bosons eaten by each vector field with the equivalence theorem. Since their effects become larger and …
Perturbative unitarity for $\wlwl$ scattering is discussed within the Randall-Sundrum model. It is shown that the exchange of massive 4D Kaluza-Klein gravitons leads to amplitudes growing linearly with the CM energy squared. Summing over KK gravitons up to a scale $\lbar$ and testing unitarity at $\rts=\lbar$, one finds that unitarity is violated for $\lbar$ below the 'naive dimensional analysis' scale, $\lnda$. It is also shown that the exchange of gravitons can substantially relax the upper limit from unitarity on the mass of the Standard Model Higgs boson - consistency with unitarity for al…
We study multi-Higgs final states in vector boson fusion (VBF) processes at the LHC and at future proton-proton colliders, focusing on the prospects for measurements at 27 TeV and at 100 TeV. We use an effective Lagrangian which includes higher-dimensional operators in the mass eigenstates which are relevant to VBF processes and relate this to specific parameterizations and models for new physics in the Higgs sector. We derive theoretical constraints on the parameter space from the unitarity of $2\to n$ scattering amplitudes and apply the results to $V V \to hh$ and $h h h$ processes, where $V…
We calculate an $s$-wave amplitude matrix for all the possible 2--to--2 body scalar boson elastic scatterings in models with three scalar doublets, including contributions from the longitudinal component of weak gauge bosons via the Equivalence Theorem Approximation. Specifically, we concentrate on the two cases with two[one] active plus one[two] inert doublet fields, referred to as I(1+2)HDM[I(2+1)HDM], under CP conservation. We obtain three analytically irreducible sub-matrices with the $3\times 3$ form and eighteen eigenvalues for the amplitude matrix as an independent set, where the same f…
Non-unitarity of the neutrino mixing matrix is expected in many scenarios with physics beyond the Standard Model. Motivated by the search for deviations from unitary, we study two neutrino counting observables: the neutrino-antineutrino gamma process and the invisible $Z$ boson decay into neutrinos. We report on new constraints for non-unitarity coming from the first of this observables. We study the potential constraints that future collider experiments will give from the invisible decay of the Z boson, that will be measured with improved precision.
The ultraviolet structure of $s$-channel mediator dark matter simplified models at hadron colliders is considered. In terms of commonly studied $s$-channel mediator simplified models it is argued that at arbitrarily high energies the perturbative description of dark matter production in high energy scattering at hadron colliders will break down in a number of cases. This is analogous to the well documented breakdown of an EFT description of dark matter collider production. With this in mind, to diagnose whether or not the use of simplified models at the LHC is valid, perturbative unitarity of …
We examine the unitarity properties of spontaneously broken non-commutative gauge theories. We find that the symmetry breaking mechanism in the non-commutative Standard Model of Chaichian et al. leads to an unavoidable violation of tree-level unitarity in gauge boson scattering at high energies. We then study a variety of simplified spontaneously broken non-commutative theories and isolate the source of this unitarity violation. Given the group theoretic restrictions endemic to non-commutative model building, we conclude that it is difficult to build a non-commutative Standard Model under the …
Weak vector boson scattering at high energies will be one of the key measurements in current and upcoming LHC runs. It is most sensitive to any new physics associated with electroweak symmetry breaking. However, a conventional EFT analysis will fail at high energies. To address this problem, we present a parameter-free prescription valid for arbitrary perturbative and non-perturbative models: the T-matrix unitarization. We describe its implementation as an asymptotically consistent reference model matched to the low-energy effective theory. We show examples of typical observables of vector-bos…
High-energy unitarity is satisfied by adding a sextet quark doublet to QCD. The sextet sector produces electroweak symmetry breaking and is predicted to give large cross-section effects at the LHC. It embeds, uniquely, in a massless SU(5) theory whose bound-state S-Matrix, potentially, reproduces the Standard Model. Infra-red chirality transitions of the massless Dirac sea play an essential dynamical role.
We derive partial-wave unitarity constraints on gauge-invariant interactions of an Axion-Like Particle (ALP) up to dimension-6 from all allowed $2\to2$ scattering processes in the limit of large center-of-mass energy. We find that the strongest bounds stem from scattering amplitudes with one external ALP and only apply to the coupling to a pair of $SU(2)_L$ gauge bosons. Couplings to $U(1)_Y$ and $SU(3)_C$ gauge bosons and to fermions are more loosely constrained.
Dark matter that was once in thermal equilibrium with the Standard Model is generally prohibited from obtaining all of its mass from the electroweak phase transition. This implies a new scale of physics and mediator particles to facilitate dark matter annihilation. In this work, we focus on dark matter that annihilates through a generic gauge boson portal. We show how partial wave unitarity places upper bounds on the dark gauge boson, dark Higgs and dark matter masses. Outside of well-defined fine-tuned regions, we find an upper bound of 9 TeV for the dark matter mass when the dark Higgs and d…
An electroweak (EW) model has been investigated (Moffat) in which the energy $E < μ=\sqrtλM_W$, where $λ$ is a gauge parameter and $M_W$ is the $W$ boson mass. For large enough $λ$ the scalar boson mass $μ=\sqrtλM_W$ can be heavy enough to avoid detection in LHC experiments. The theory is perturbatively renormalizable for the decoupled scalar interactions. The Born approximation tree graph unitarity can be ensured by postulating that the effective coupling constant $g_{\rm eff}(s)$ vanishes as $1/\sqrt{s}$ or faster as $s\rightarrow\infty$, predicting that the EW interactions become weaker at …
We list all possible dim=6 CP conserving and SU(3)* SU(2)*U(1) gauge invariant interactions, which could be generated in case no new particles would be reachable in the future Colliders, and the only observable New Physics would be in the form of new interactions affecting the scalar sector and the quarks of the third family. These interactions are described by operators involving the standard model scalar field, the quarks of the third family and the gauge bosons. Subsequently, we identify those operators which do not contribute to LEP1 (and lower energy) observables at tree level and are not…
In this paper we present the partial wave unitarity bound in the parameter space of dimension-5 and dimension-6 effective operators that arise in a compositeness scenario. These are routinely used in experimental searches at the LHC to constraint contact and gauge interactions between ordinary Standard Model fermions and excited (composite) states of mass $M$. After deducing the unitarity bound for the production process of a composite neutrino, we implement such bound and compare it with the recent experimental exclusion curves for Run 2, the High-Luminosity and High-Energy configurations of …
We study bounds on Higgs boson masses from perturbative unitarity in the Georgi-Machacek model, whose Higgs sector is composed of a scalar isospin doublet, a real and a complex isospin triplet fields. This model can be compatible with the electroweak precision data without fine tuning because of the imposed global SU(2)_R symmetry in the Higgs potential, by which the electroweak rho parameter is unity at the tree level. All possible two-body elastic-scattering channels are taken into account to evaluate the S-wave amplitude matrix, and then the condition of perturbative unitarity is imposed on…
Tree-level unitarity constraints on the masses of the Higgs bosons in the general Two Higgs Doublet Model (THDM) are studied. We first consider the case where the Higgs potential is invariant under a discrete symmetry transformation, and derive strong constraints on the mass of the lightest CP-even Higgs boson ($M_h$) as a function of $\tanβ$. We then show that the inclusion of the discrete symmetry breaking term weakens the mass bounds considerably. It is suggested that a measurement of $M_h$ and $\tanβ$ may enable discrimination between the two Higgs potentials.
In the light of the recent LHC data, we study precision tests sensitive to the violation of lepton universality, in particular the violation of unitarity in neutrino mixing. Keeping all data we find no satisfatory fit, even allowing for violations of unitarity in neutrino mixing. Leaving out sin$^2 θ_{\scriptsize \mbox{eff}}$ from the hadronic forward-backward asymmetry at LEP, we find a good fit to the data with some evidence of lepton universality violation at the $\mathcal{O}(10^{-3})$ level.
We investigate unitarity bounds in the most general two Higgs doublet model without a discrete $Z_2$ symmetry nor CP conservation. S-wave amplitudes for two-body elastic scatterings of Nambu-Goldstone bosons and physical Higgs bosons are calculated at high energies for all possible initial and final states (14 neutral, 8 singly-charged and 3 doubly-charged states). We obtain analytic formulae for the block-diagonalized scattering matrix by the classification of the two body scattering states using the conserved quantum numbers at high energies. Imposing the condition of perturbative unitarity …
The success of the experimental program at the Tevatron re-inforced the idea that precision physics at hadron colliders is desirable and, indeed, possible. The Tevatron data strongly suggests that one-loop computations in QCD describe hard scattering well. Extrapolating this observation to the LHC, we conclude that knowledge of many short-distance processes at next-to-leading order may be required to describe the physics of hard scattering. While the field of one-loop computations is quite mature, parton multiplicities in hard LHC events are so high that traditional computational techniques be…
Searches for charged Higgs bosons are an integral part of current and future investigations at the LHC. The LHC Higgs Cross Section Working Group (LHCHXSWG) was created to provide cross sections, branching ratios, analysis strategies etc. for Higgs boson searches at the LHC. We briefly review progress and results for charged Higgs bosons in and for the LHCHXSWG.
Proceeding from optical analogy we propose a new physical interpretation of unitarity saturation leading to antishadowing as a reflective scattering. This interpretation of antishadowing is related to the non-perturbative aspects of strong interactions and follows from the specific property of the unitarity saturation when elastic $S$-matrix $S(s,b)|_{b=0}\to -1$ at $s\to \infty$. The analogy with Berry phase and experimental consequences of the proposed interpretation as reflective scattering at the LHC and in the cosmic rays studies are discussed.
High-energy unitarity is argued to select a special version of QCD as the strong interaction. Electroweak symmetry breaking has to be due to a new sextet quark sector - that will produce large cross-section effects at the LHC. The sextet sector embeds, uniquely, in a massless SU(5) theory that potentially generates the states and interactions of the Standard Model within a bound-state S-Matrix. Infra-red chirality transitions of the massless Dirac sea play an essential dynamical role.
We use the results of Maher {\em et al.\/} (preceding paper) to construct the matrix of $j=0$ partial-wave two-body and $2\rightarrow3$ scattering amplitudes for the scattering of longitudinally polarized gauge bosons $W_L^\pm$, $Z_L$ and Higgs bosons $H$ correct to two loops in the high-energy, heavy-Higgs limit $\sqrt{s}\gg M_H\gg M_W$. We show explicitly that the energy dependence of the $2\rightarrow2$ amplitudes can be completely absorbed into a running quartic Higgs coupling $λ_s= λ_s(s,M_H^2)$ and factors which involve small anomalous dimensions and remain near unity. After diagonalizin…
We show that the deviation from exponential behavior of the diffraction cone observed near t=-0.1 GeV^2 both at ISR and the LHC (so-called break) follows from a two-pion loop in the t channel, imposed by unitarity. By using a simple Regge-pole model, we extrapolate the "break" from the ISR energy region to that of the LHC.
