arXiv subjects

Kenneth Lane

Publications and source records attributed to Kenneth Lane.

At least 37 records · Page 2Linked to original sources

arXiv2009

An Effective Lagrangian for Low-Scale Technicolor

We present an effective Lagrangian for low-scale technicolor. It describes the interactions at energies near the mass of the lowest-lying bound states of the lightest technifermion doublet -- the spin-one $ρ_T,ω_T, a_T, f_T$ and the corresponding technipions $π_T$. This Lagrangian is intended to put on firmer ground the technicolor straw-man phenomenology used for collider searches of low-scale technicolor. The technivectors are described using the hidden local symmetry (HLS) formalism of Bando et al. The Lagrangian is based on $SU(2)\otimes U(1)\otimes U(2)_L \otimes U(2)_R$, where $SU(2)\otimes U(1)$ is the electroweak gauge group and $U(2)_L \otimes U(2)_R$ is the HLS gauge group. Special attention is paid to the higher-derivative standard HLS and Wess-Zumino-Witten interactions needed to describe radiative and other decays of the $a_T$ and $ρ_T/ω_T$, respectively.

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arXiv2008

Low-Scale Technicolor at the Tevatron and LHC

The Tevatron experiments CDF and DO are close to making definitive statements about the technicolor discovery mode rho_T -> W pi_T for M(rho_T) <~ 230 GeV and M(pi_T) <~ 125 GeV. We propose new incisive tests for this mode and searches for others that may be feasible at the Tevatron and certainly are at the LHC. The other searches include two long discussed, namely, omega_T -> gamma pi_T and l+l-, and a new one -- for the I^G J^{PC} = 1^- 1^{++} partner, a_T, of the rho_T. Adopting the argument that the technicolor contribution to S is reduced if M(a_T) is near M(rho_T), we enumerate important a_T decays and estimate production rates at the colliders.

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arXiv2006

Search for Low-Scale Technicolor at the Tevatron

CDF and D0 each have more than 1 inverse femtobarn of data on tape, and their stores are increasing. This should be sufficient to carry out significant searches for low-scale technicolor in rho_T --> W pi_T and omega_T, rho_T --> gamma pi_T, processes whose cross sections may be as large as several picobarns. In this note we motivate and describe the Technicolor Straw Man framework for these processes and we urge that they be sought soon in the Run 2 data. (This paper is a contribution to the TeV4LHC Landscapes project.)

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arXiv2006

New states above charm threshold

We revise and extend expectations for the properties of charmonium states that lie above charm threshold, in light of new experimental information. We refine the Cornell coupled-channel model for the coupling of c-cbar levels to two-meson states, defining resonance masses and widths by pole positions in the complex energy plane, and suggest new targets for experiment.

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arXiv2005

A New Mechanism for Light Composite Higgs Bosons

Repeated symmetry-breaking and restoration phase transitions occur as one traverses the parameter space of interactions competing to align the vacuum. This phenomenon, augmented with a topcolor-like interaction, can make a composite Higgs boson's mass and vacuum expectation value naturally much less than its underlying structure scale, without introducing new symmetries and their associated TeV-scale particles. We illustrate it by reconstructing a simple light composite Higgs model of electroweak symmetry breaking proposed by Georgi and Kaplan.

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arXiv2005

Accidental Goldstone Bosons

We study vacuum alignment in theories in which the chiral symmetry of a set of massless fermions is both spontaneously and explicitly broken. We find that transitions occur between different phases of the fermions' CP symmetry as parameters in their symmetry breaking Hamiltonian are varied. We identify a new phase that we call pseudoCP-conserving. We observe first and second-order transitions between the various phases. At a second-order (and possibly first-order) transition a pseudoGoldstone boson becomes massless as a consequence of a spontaneous change in the discrete, but not the continuous, symmetry of the ground state. We relate the masslessness of these ``accidental Goldstone bosons'' (AGBs) bosons to singularities of the order parameter for the phase transition. The relative frequency of CP-phase transitions makes it commonplace for the AGBs to be light, much lighter than their underlying strong interaction scale. We investigate the AGBs' potential for serving as light composite Higgs bosons by studying their vacuum expectation values, finding promising results: AGB vevs are also often much less than their strong scale.

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arXiv2004

CP Violation and Flavor Mixing in Technicolor Theories

Vacuum alignment in technicolor models provides an attractive origin for the quarks' CP violation and, possibly, a natural solution for the strong-CP problem of QCD. We discuss these topics in this paper. Then we apply them to determine plausible mixing matrices for left and right-handed quarks. These matrices determine the Cabibbo-Kobayashi-Maskawa matrix as well as new mixing angles and phases that are observable in extended technicolor (ETC) and topcolor (TC2) interactions. We determine the contributions of these new interactions to CP-violating and mixing observables in the K^0, B_d and B_s systems. Consistency with mixing and CP violation in the K^0 system requires assuming that ETC interactions are electroweak generation conserving even if technicolor has a walking gauge coupling. Large ETC gauge boson masses and small intergenerational mixing then result in negligibly small ETC contributions to B-meson mixing and CP violation and to Re(epsilon'/epsilon). We confirm our earlier strong lower bounds on TC2 gauge boson masses from B_d--B_d-bar mixing. We then pay special attention to the possibility that current experiments indicate a deviation from standard model expectations of the values of sin(2 beta) measured in B_d -> J/psi K_S, phi K_S, eta' K_S, and pi K_S, studying the ability of TC2 to account for these. We also determine the TC2 contribution to Delta M_{B_s} and to Re(epsilon'/epsilon), and find them to be appreciable.

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arXiv2004

Charmonium levels near threshold and the narrow state $X(3872) \to π^{+}π^{-}\jpsi$

We explore the influence of open-charm channels on charmonium properties, and profile the 1:3D2, 1:3D3 and 2:1P1 charmonium candidates for X(3872). The favored candidates, the 1:3D2 and 1:3D3 levels, both have prominent radiative decays. The 1:3D2 might be visible in the $D^{0}\bar{D}^{*0}$ channel, while the dominant decay of the 1:3D3 state should be into $D\bar{D}$. We propose that additional discrete charmonium levels can be discovered as narrow resonances of charmed and anticharmed mesons.

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arXiv2002

The Collider Phenomenology of Technihadrons in the Technicolor Straw Man Model

We discuss the phenomenology of the lightest SU(3)_C singlet and non-singlet technihadrons in the Straw Man Model of low-scale technicolor (TCSM). The technihadrons are assumed to be those arising in topcolor--assisted technicolor models in which topcolor is broken by technifermion condensates. We improve upon the description of the color--singlet sector presented in our earlier paper introducing the TCSM (hep-ph/9903369). These improvements are most important for subprocess energies well below the masses of the technirho and techniomega, and, therefore, apply especially to e+e- colliders such as LEP and a low--energy linear collider. In the color--octet sector, we consider mixing of the gluon, the coloron V_8 from topcolor breaking, and four isosinglet color--octet technirho mesons. We assume, as expected in walking technicolor, that these technirhos decay into qbar-q, gg, and g-technipion final states, but not into technipion pairs. All the TCSM production and decay processes discussed here are included in the event generator Pythia. We present several simulations appropriate for the Tevatron Collider, and suggest benchmark model lines for further experimental investigation.

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arXiv2002

Deconstructing Dimensional Deconstruction

Dimensional deconstruction (DD) abstracts from higher dimensional models features of related 4--dimensional ones. DD was proposed in Refs.[1,2,3] as a scheme for constructing models of {\it naturally} light composite Higgs boson. These are models in which--{\it without fine--tuning of parameters}--the composite Higgs's mass M and vacuum expectation value v are much lighter than its binding energy scale Λ. We review the basic idea of DD. It is easy to arrange M << Λ. We show, however, that DD fails to give v << Λin a model that is supposed to contain a naturally light composite Higgs [4].

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arXiv2002

B-Meson Gateways to Missing Charmonium Levels

We outline a coherent strategy for exploring the four remaining narrow charmonium states [$η_{c}^{\prime}(2\slj{1}{1}{0})$, $h_{c}(1\slj{1}{2}{1})$, $η_{c2}(1\slj{1}{3}{2})$, and $ψ_{2}(1\slj{3}{3}{2})$] expected to lie below charm threshold. Produced in $B$-meson decays, these levels should be identifiable \textit{now} via striking radiative transitions among charmonium levels and in exclusive final states of kaons and pions. Their production and decay rates will provide much needed new tests for theoretical descriptions of heavy quarkonia.

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arXiv2002

Resonant and Non-Resonant Effects in Photon-Technipion Production at Lepton Colliders

Lepton collider experiments can search for light technipions in final states made striking by the presence of an energetic photon: $e+e- \to \photon\technipion$. To date, searches have focused on either production through anomalous coupling of the technipions to electroweak gauge bosons or on production through a technivector meson (\technirho, \techniomega) resonance. This paper creates a combined framework in which both contributions are included. This will allow stronger and more accurate limits on technipion production to be set using existing data from LEP or future data from a higher-energy linear collider. We provide explicit formulas and sample calculations (analytic and Pythia) in the framework of the Technicolor Straw Man Model, a model that includes light technihadrons.

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arXiv2002

Two Lectures on Technicolor

These two lectures on technicolor and extended technicolor (ETC) were presented at l'Ecole de GIF at LAPP, Annecy-le-Vieux, France, in September 2001. In Lecture I, the motivation and structure of this theory of dynamical breaking of electroweak and flavor symmetries is summarized. The main phenomenological obstacles to this picture--flavor-changing neutral currents, precision electroweak measurements, and the large top-quark mass--are reviewed. Then, their proposed resolutions--walking technicolor and topcolor-assisted technicolor are discussed. In Lecture II, a scenario for CP violation is presented based on vacuum alignment for technifermions and quarks. It has the novel feature of CP--violating phases that are rational multiples of pi to better than one part in 10^{10} without fine-tuning of parameters. The scheme thereby avoids light axions and a massless up quark. The mixing of neutral mesons, the mechanism of top--quark mass generation, and the CP--violating parameters epsilon and sin(2 beta) strongly constrain the form of ETC--generated quark mass matrices.

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arXiv2002

A Case Study in Dimensional Deconstruction

We test Arkani-Hamed et al.'s dimensional deconstruction on a model that is predicted to have a naturally light composite Higgs boson, i.e., one whose mass M is much less than its binding scale Λ, and whose quartic coupling λis large, so that its vacuum expectation value v \sim M/\sqrtλ << Λalso. We consider two different underlying dynamics--UV completions--at the scale Λfor this model. We find that the expectation from dimensional deconstruction is not realized and that low energy details depend crucially on the UV completion. In one case, M << Λand λ<< 1, hence, v \sim Λ. In the other, λcan be large or small, but then so is M, and v is still O(Λ).

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arXiv2001

Strong and Weak CP Violation in Technicolor

I discuss vacuum alignment and CP violation in technicolor theories of electroweak and flavor symmetry breaking. I review the surprising appearance of rational phase solutions in the technifermion sector and propose a new solution of the strong CP problem of quarks. I then discuss the sources of weak CP violation, in both the CKM matrix and the suppressed extended technicolor and topcolor--assisted technicolor interactions. It is easy to reproduce the observed value of the neutral kaon CP-violating parameter epsilon from these interactions.

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arXiv2001

Kzero--Anti-Kzero and Bzero--Anti-Bzero Constraints On Technicolor

I propose a resolution of the strong CP problem of quarks based on vacuum alignment in theories of dynamically broken electroweak and flavor symmetries. Mixing in the neutral B and K--meson systems is used to restrict the form of quark mass and mixing matrices and to constrain the masses of the topcolor gauge bosons V_8 and Z' to be greater than 5 TeV. The K^0 mixing parameter epsilon is calculated for models whose quark mass matrix leads to weak, but not strong, CP violation. It is easy to accomodate its value in some models while, in others, no reasonable combination of extended technicolor and topcolor masses can account for epsilon.

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arXiv2001

Anti-B-B Mixing Constrains Topcolor-Assisted Technicolor

We argue that extended technicolor augmented with topcolor requires that all mixing between the third and the first two quark generations resides in the mixing matrix of left-handed down quarks. Then, the anti-B_d--B_d mixing that occurs in topcolor models constrains the coloron and Z' boson masses to be greater than about 5 TeV. This implies fine tuning of the topcolor couplings to better than 1%.

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arXiv2001

New Model-Independent Limit on Muon Substructure

If the discrepancy between the theoretical and newly measured values of the muon's anomalous magnetic moment is ascribed to muon substructure, there results an improved model--independent limit on its energy scale, 1.2 TeV < Lambda_mu < 3.2 TeV at 95% C.L.

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