118447239
Standard model gauging of the Wess-Zumino-Witten term: Anomalies, global currents, and pseudo-Chern-Simons interactions
The standard model SU(2){sub L}xU(1){sub Y} gauging of the Wess-Zumino-Witten term requires a modified counterterm when background fields, needed to generate the full set of currents, are introduced. The modified counterterm plays an essential role in properly defining covariant global currents and their anomalies. For example, it is required in order to correctly derive the gauge-invariant baryon number current and its anomalous divergence. The background fields can also be promoted to a description of the physical spin-1 vector and axial-vector mesons in QCD and the counterterm leads to novel interactions. These are (pseudo)Chern-Simons terms, such as {epsilon}{sup {mu}}{sup {nu}}{sup {rho}}{sup {sigma}}{omega}{sub {mu}}Z{sub {nu}}{partial_derivative}{sub {rho}}A{sub {sigma}} and {epsilon}{sup {mu}}{sup {nu}}{sup {rho}}{sup {sigma}}{rho}{sub {mu}}{sup {+-}}W{sub {nu}}{sup {+-}}{partial_derivative}{sub {rho}}A{sub {sigma}} that mediate new interactions between neutrinos and photons at finite baryon density.
10472717
Chiral multiplets of heavy-light mesons
The recent discovery of a narrow resonance in ${D}_{s}{\ensuremath{\pi}}^{0}$ by the BaBar Collaboration is consistent with the interpretation of a heavy ${J}^{P}{(0}^{+}{,1}^{+})$ spin multiplet. This system is the parity partner of the ground state ${(0}^{\ensuremath{-}}{,1}^{\ensuremath{-}})$ multiplet, which we argue is required in the implementation of ${\mathrm{SU}(3)}_{L}\ifmmode\times\else\texttimes\fi{}{\mathrm{SU}(3)}_{R}$ chiral symmetry in heavy-light meson systems. The ${(0}^{+}{,1}^{+})\ensuremath{\rightarrow}{(0}^{\ensuremath{-}}{,1}^{\ensuremath{-}})+\ensuremath{\pi}$ transition couplings satisfy a Goldberger-Treiman relation, ${g}_{\ensuremath{\pi}}=\ensuremath{\Delta}{M/f}_{\ensuremath{\pi}},$ where $\ensuremath{\Delta}M$ is the mass gap. The BaBar resonance fits the ${0}^{+}$ state, with a kinematically blocked principal decay mode to $D+K.$ The allowed ${D}_{s}+\ensuremath{\pi},$ ${D}_{s}+2\ensuremath{\pi},$ and electromagnetic transitions are computed from the full chiral theory and found to be suppressed, consistent with the narrowness of the state. This state establishes the chiral mass difference for all such heavy-quark chiral multiplets, and precise predictions exist for the analogous ${B}_{s}$ and strange doubly heavy baryon states.
11755173
Cosmology with ultralight pseudo Nambu-Goldstone bosons.
We explore the cosmological implications of an ultralight pseudo Nambu-Goldstone boson. With global spontaneous symmetry breaking scale $f\ensuremath{\simeq}{10}^{18}\mathrm{GeV}$ and explicit breaking scale comparable to Mikheyev-Smirnov-Wolfenstein neutrino masses, $M\ensuremath{\sim}{10}^{\ensuremath{-}3}\mathrm{eV}$, such a field, which acquires a mass ${m}_{\ensuremath{\varphi}}\ensuremath{\sim}{M}^{2}/f\ensuremath{\sim}{H}_{0}$, would currently dominate the energy density of the Universe. The field acts as an effective cosmological constant before relaxing into a condensate of nonrelativistic bosons. Such a model can reconcile dynamical estimates of the density parameter, ${\ensuremath{\Omega}}_{m}\ensuremath{\sim}0.2$, with a spatially flat universe, yielding ${H}_{0}{t}_{0}\ensuremath{\simeq}1$ consistent with limits from gravitational lens statistics.
122717656
Renormalization in indefinite metric theories
We consider the Lee model,V ⇆ N+θ, and a two neutral scalar meson model with indefinite metrics. It is shown that in general the coupling will cause positive definite bare states to become negative length dressed states through renormalization effects. This can render the theory unphysical depending upon the auxiliary conditions imposed with the indefinite metric.
119473346
Renormalization group fixed points and the Higgs boson spectrum
Abstract We study numerically the renormalization group equations for the Higgs potential of the two-doublet model assuming perturbative unification and sufficiently large initial quartic and Higgs-Yukawa couplings such that the full nonlinearities interplay. We obtain predictions for the physical Higgs boson spectrum in the two-doublet model up to systematic differences in fermion coupling schemes. Unambiguous predictions emerge only when there exists a heavy generation in which quarks couple to both doublets. In other cases we find that the potential can become quartically unstable at low energies for arbitrary initial stable values of the coupling constants.
15028896
Fractal theory space: Space-time of noninteger dimensionality
We construct matter field theories in ``theory space'' that are fractal, and invariant under geometrical renormalization group (RG) transformations. We treat in detail complex scalars, and discuss issues related to fermions, chirality, and Yang-Mills gauge fields. In the continuum limit these models describe physics in a noninteger spatial dimension which appears above a RG invariant ``compactification scale,'' M. The energy distribution of KK modes above M is controlled by an exponent in a scaling relation of the vacuum energy (Coleman-Weinberg potential), and corresponds to the dimensionality. For truncated-s-simplex lattices with coordination number s the spacetime dimensionality is 1+(3+2ln(s)/ln(s+2)). The computations in theory space involve subtleties, owing to the 1+3 kinetic terms, yet the resulting dimensionalites are equivalent to thermal spin systems. Physical implications are discussed.
119530771
Acceleration in the linear non-scaling fixed-field alternating-gradient accelerator EMMA
In a fixed-field alternating-gradient (FFAG) accelerator, eliminating pulsed magnet operation permits rapid acceleration to synchrotron energies, but with a much higher beam-pulse repetition rate. Conceived in the 1950s, FFAGs are enjoying renewed interest, fuelled by the need to rapidly accelerate unstable muons for future high-energy physics colliders. Until now a ‘scaling’ principle has been applied to avoid beam blow-up and loss. Removing this restriction produces a new breed of FFAG, a non-scaling variant, allowing powerful advances in machine characteristics. We report on the first non-scaling FFAG, in which orbits are compacted to within 10 mm in radius over an electron momentum range of 12–18 MeV/c. In this strictly linear-gradient FFAG, unstable beam regions are crossed, but acceleration via a novel serpentine channel is so rapid that no significant beam disruption is observed. This result has significant implications for future particle accelerators, particularly muon and high-intensity proton accelerators.
55769041
The High Voltage System for the High Intensity CERN Proton Source
For the RFQ injector mounted on the CERN 50 MeV proton linac, the source needs to provide about 300 mA of 100 keV beam in pulses of 20 to 150 μs at 1 Hz. Although the high voltage supply is fairly conventional, a number of measures had to be taken to ensure not only the reliability of the source electronics, but also other equipments installed in the near vicinity. In view of the high current demanded from the source, a new and very simple form of beam load compensation was developed to stabilise the preinjector voltage to values acceptable to the RFQ.
55772711
Accelerating and separating mixed beams of ions with similar charge to mass ratio in the CERN PS complex
Sumrarv mixture were found. Four Booster rings were filled with this beam, captured on h = 10, with a harmonic change (10 + 5) during acceleration [Ref. 41. Sixteen (out of twenty) bunches were transferred to the PS at a magnetic rigidity corresponding to 815 HeV protons (i.e. 258.6 MeV/u). The PS accelerated this beam on the usual h = 20 to transition (6 GeV/u) where the two species, virtually undistinguishable until this stage g occupied different radial orbits and cPf!d be sgparated by RF gymnastics. Four batches of S or In autumn 1987, sulphur 32 ions were accelerated by the CERN machines to a world record energy of 6.4 TeV. An Electron Cyclotron ReSOnanCe source produces sulphur ions as a 5 per cent ‘contamination” of an oxygen ion beam. As their charge-to-mass ratios differ by only 5.4 E-4 , the two species are not distinguishable by the downstream accelerators (RFQ, Linac 1, PSB) , though measurable in a specially equipped spectrometer line. In this way, enough current is available for controlled acceleration at low beta in the PSB. However, at phase transition energy in the PS about 6 GeV/nucleon (CeV/u) this synchrotron becomes an extremely fine spectrometer, with sulphur 16t ions being driven inwards, and oxygen 8t outwards. This can be used for separating the beams by manipulating the low-level radio-frequency system at transition, SO that either oxygen or sulphur is selected. Indeed, the SPS could be fed with a fairly intense oxygen beam for setting-up, and later with some 2E7 sulphur ions per PS cycle. The required RF manipulations, the present understanding on beam dynamics at transition, as well as diagnostic techniques for determining the amount of sulphur are presented.
53579013
Observability of Higgs produced with top quarks and decaying to bottom quarks
The decay, H → bb, is dominant for a Standard Model Higgs boson in the mass range just above the exclusion limit of 114.4 GeV/c 2 reported by the LEP experiments. Unfortunately, an overwhelming abundance of b¯ b events arising from more mundane sources, together with the lack of precision inherent in the reconstruction of the Higgs mass, renders this decay modeaprioriundetectable in the case of direct Higgs production at the LHC. It is therefore of no small interest to investigate whether H → bb can be observed in those cases where the Higgs is produced in association with other massive particles. In this note, the results of a study of Higgs bosons produced in association with top quarks and decaying via H → bb are presented. The study was performed as realistically as possible by employing a full and detailed Monte Carlo simulation of the CMS detector followed by the application of trigger and reconstruction algorithms that were developed for use with real data. Important systematic effects resulting from such sources as the uncertainties in the jet energy scale and the estimated rates for correctly tagging b jets or mistagging non-b jets have been taken into account. The impact of large theoretical uncertainties in the cross sections for t tp lusN jets processes due to an absence of next-to-leading order calculations is also considered.
55116338
Experiments on the Pulsed Afterglow Operation of an ECR Ion Source
Various experiments have been performed on the 14.5 GHz ECR4 in order to improve the beam yield. The source operates in pulsed “afterglow” mode, and provides currents >120 e A of Pb 27+ to the Heavy Ion Facility on an operational basis. In the search for higher beam intensities, the effects of a pulsed biased disk on axis at the injection side were investigated with different pulse timing and voltage settings. Different plasma electrode geometries were also tested, including running the source without a plasma electrode. The use of CF 4 as mixing gas was investigated, and high secondary electron emission materials, such as LaB 6 and Al2O3, were inserted inside the plasma chamber in an attempt to increase the cold electron density. No proof for higher intensities was seen for any of the tested modifications. On the contrary, several of the modifications resulted in lower source performance, and less stability. Although the source has previously proved to have very stable modes of operation, during the last physics run, after the above tests, the stability decreased and the source settings were very different from the normal operation values.