A new conference series brings different disciplines together.
The International Conference on New Frontiers in Physics (ICFP) aims to promote scientific exchange between different areas of fundamental physics, with particular emphasis on future plans and related open questions. The first in the new series, ICFP 2012, which took place in Kolymbari, Crete, attracted 140 participants from fields ranging from particle physics and cosmology to quantum physics and the foundations of quantum mechanics – a discipline awarded the 2012 Nobel Prize in Physics. The following highlights reflect the main themes of the plenary talks, which were further elaborated in many parallel sessions.
One of the last conferences to hear enticing hints of an imminent Higgs-boson discovery
ICFP 2012 was one of the last conferences to hear enticing hints of an imminent Higgs-boson discovery, as the ATLAS and CMS collaborations at the LHC presented candidate signals for the Higgs boson with a local significance of 2.5–2.8σ at a mass of 125–126 GeV. At the same time, the CDF and DØ collaborations from the Tevatron at Fermilab also reported an excess near the same mass region with a local significance of 2.7σ. In other presentations, state-of-the-art theoretical calculations of the cross-section for a Standard Model Higgs boson were described, as well as a prediction for the Higgs boson mass of 121–126 GeV and the supersymmetric spectrum from finite unified theories. Implications beyond the Standard Model of both the mass and the large diphoton rate observed were also discussed. Reports on experimental searches for new physics, such as excited leptons, heavy neutrinos, new bosons, supersymmetry and gravity signatures, went further beyond the Standard Model, as did discussions of string theory and extra dimensions. Results from the LHC on di-jets accompanying vector bosons excluded at 95% confidence level the structure that the CDF experiment saw two years ago.
Talks on hadrons and QCD covered the latest lattice QCD results and presented theoretical predictions and the status of new states with heavy quarks and exotic hadrons, such as the Zb states discovered in 2011 by the Belle experiment at KEK. The latter are consistent with a minimal content of two quarks and two antiquarks. Within a new extended quark model that has both quarks and diquarks as building blocks, new QCD effects and interpretations emerge; for example, there are no radial excitations in low-energy QCD and hadrons can shrink. Reflecting the interdisciplinary theme of the conference, one approach to the description of the QCD phase diagram that was discussed involves a holographic model; Lorentz violation and holography were also discussed.
Highlights from heavy-ion experiments confirm that the hot and dense medium created in heavy-ion collisions behaves like a strongly interacting, almost perfect liquid – the strongly interacting quark–gluon plasma. The estimates of shear viscosity are consistent with the lower bound of the anti-de Sitter/conformal field-theory correspondence. The generated flow seems to affect even heavy particles, while jets and hadrons with high-transverse momentum are strongly quenched traversing this medium. An analogy was made between the higher-order flow coefficients that originate from the initial fluctuations of the “Little Bang” in central heavy-ion collisions and the measurements of the cosmic microwave background radiation that explore the initial fluctuations of the early universe after the Big Bang. Outstanding results have come from measurements of quarkonia, such as the indication of sequential suppression of quarkonia and of possible J/ψ regeneration at the LHC. The direct Υ(1S) state is not suppressed either at Brookhaven’s Relativistic Heavy-Ion Collider (RHIC) or at the LHC, while charmonium and bottomonium states with smaller dissociation temperatures than the Υ(1S), show a suppression at both RHIC and the LHC – as expected for a deconfined plasma of quarks and gluons within a colour-screening scenario.
An overview described the status of rare decays and CP violation, while results on the latter from LHCb and other LHC experiments set strong constraints on models and led to intriguing results that await an explanation either inside or outside the Standard Model. In particular, the isospin asymmetry in B → K μ+μ– differs from the expectation by 4σ, while CP violation in the charm sector shows a 3.5σ deviation from the CP-conserving hypothesis. Results from the BaBar experiment at SLAC highlight a significant excess of events in B → D*τ ν decays at 3.4σ above the Standard-Model expectation, thus ruling out the type II two-Higgs-doublet model. BaBar has also made a direct observation of time-reversal violation at the 14σ level. The CP violation seen by LHCb in D-meson decays could arise from a fourth generation of quarks and leptons.
In the neutrino sector, an overview described the status of experiments on neutrinoless double-beta decay and their expected reach. According to the “forecast” given, the claimed evidence of the signal reported in 2001 by a subset of the Heidelberg-Moscow collaboration will be checked by the GERDA experiment in the Gran Sasso National Laboratory in the near future. Currently, the EXO-200 experiment sets the most competitive limit in the field and almost completely rules out the claim. The OPERA collaboration reported on new oscillation results from the search for ντ appearance, preliminary limits on oscillation parameters from the search for νμ → νe and an update on the measurement of neutrino velocity. New results from the T2K experiment in Japan confirm the first evidence for νe appearance presented in 2011 and provide a measurement of sin22θ13. In reactor experiments, the Double Chooz collaboration presented results on sin22θ13 that exclude the non-oscillation scenario at 3.1σ, while the high-precision measurements of sin22θ13 presented by the Daya Bay collaboration exclude a zero value for θ13 at more than 7σ.
The quest to dark matter
The quest to determine the nature of dark matter is a challenge at the boundary of particle physics and astrophysics. Possible hints, for example from the Fermi Gamma-ray Space Telescope and the PAMELA experiment in space, were discussed in an overview of experimental searches and theoretical implications and expectations. Other results included limits on compact halo objects as dark matter obtained from gravitational microlensing, as well as the status of the Alpha Magnetic Spectrometer (AMS-02), which has been in orbit since May 2011. The status and recent upgrades of the DAMA/LIBRA experiment and its observation at 8.9σ for a candidate signal for dark-matter particles in the galactic halo, through an annual modulation signature, were reviewed at the conference, together with detailed studies of background. Other talks covered primordial scalar perturbations via conformal mechanisms and the experimental status of the Dark Energy Survey.
At a more mathematical level, participants learnt how gravity can be viewed as emerging out of the differential calculus in non-commutative geometry, with effects that include a separation of the inertial and gravitational masses of a test particle as its mass approaches the Planck mass. Aspects of string cosmology included a review of bouncing string-cosmologies in which the Big Bang is no longer regarded as the beginning of time, as well as a presentation on how dilaton-field dominance in early epochs enlarges the cosmologically allowed parameter space for supersymmetry at the LHC.
Talks on quantum physics covered, for example, Aharonov’s two-state vector formalism, in which hidden variables may exist if the requirement of causality is relaxed to allow – under appropriate circumstances – the effects of future events on past measurements. Transaction and non-locality in quantum field theory and cosmological consequences of a de Sitter non-local vacuum, involving David Bohm’s “holomovement” ideas, were also discussed, providing a link between cosmology and quantum physics, as were classical and quantum information acquisition, measurement and the positive-operator valued measure. An overview of quantum physics with massive objects included among other topics, the possibility of testing the predictions of quantum gravity, as well as the experimental perspectives of atom–photon interactions.
The future of physics
At a broader level, an overview talk presented the European Physical Society and its activities. Moreover, looking forward to the future generations of physicists, a presentation on educational projects was given to high-school teachers in nearby Chania, the second-largest city on Crete.
Sessions during the last two days of the conference addressed the future plans of particle and nuclear physics. These included the status of the eRHIC electron–ion collider project at Brookhaven and the Nuclotron-based Ion Collider facility at JINR, as well as an overview and outlook on heavy-ion collisions at the LHC. There were also presentations on the status and plans of major particle-physics projects, namely the Muon Collider, the International Linear Collider, the Compact Linear Collider and Super B. In addition, CERN’s future plans were highlighted, as were the ideas and actions of the European Strategy for Particle Physics group and its update plan, which is currently under preparation. The conference closed with an overview of the activities of the European Committee for Future Accelerators.
To prepare not only the students but all of the audience for an interdisciplinary week, a day of lectures preceded the conference. Discussions during the sessions and more informally, then offered the possibility to explore interdisciplinary knowledge. Results from these interactions appear in the papers contributed to the conference proceedings, which will be peer reviewed and published in the EPJ Web of Conferences in 2013.