118239758
Suppose We Don’t Find SUSY?
The Higgs boson discovery will uncover new organizing principles of physics beyond the Standard Model. This may well inaugurate supersymmetry. However, following the example of Kepler, we take a look at how other, non‐supersymmetric, and seemingly ad hoc, ideas that may shape the short‐distance structure beyond the SM in unconventional and dynamical ways.
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.
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.
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.
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.
137367618
The status of the electron cooling device for LEAR
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.
122380850
New operational beam for the CERN heavy ion program
After 9 yr of delivering lead ions to the SPS fixed target physics program, a new beam was requested for the 2003 physics period, namely indium. The operational requirements and present status of the source will be presented together with the solutions to some of the problems experienced.
14475053
EXPERIENCE WITH THE GTS-LHC ION SOURCE
For the heavy ion programme of the LHC a new ECRIS type heavy ion source had to be designed and built for Linac3 to fullfill the intensity requirements. Experience acquired during the installation and commissioning of the source and during operation for the LEIR ring commissioning will be presented. The performance of the source and its reliability are evaluated. Further requirements for high reliability, low down time, easy maintenance and for future physics needs will be discussed.
125438498
Top quark mass measurements
The top quark, with its extraordinarily large mass (nearly that of a gold atom), plays a significant role in the phenomenology of EWSB in the Standard Model. In particular, the top quark mass when combined with the W mass constrains the mass of the as yet unobserved Higgs boson. Thus, a precise determination of the mass of the top quark is a principal goal of the CDF and D0 experiments. With the data collected thus far in Runs 1 and 2 of the Tevatron, CDF and D0 have measured the top quark mass in both the lepton+jets and dilepton decay channels using a variety of complementary experimental techniques. The author presents an overview of the most recent of the measurements.