Fundamental Interactions

PREFACE.

CONTENTS.

Nuclear physics has a long and productive history of application to astrophysics which continues today. Advances in the accuracy and breadth of astrophysical data and theory drive the need for better experimental and theoretical understanding of the underlying nuclear physics. This paper will review some of the scenarios where nuclear physics plays an important role, including Big Bang Nucleosynthesis, neutrino production by our sun, nucleosynthesis in novae, the creation of elements heavier than iron, and neutron stars. Big-bang nucleosynthesis is concerned with the formation of elements with A ≤ 7 in the early Universe; the primary nuclear physics inputs required are few-nucleon reaction cross sections. The nucleosynthesis of heavier elements involves a variety of proton-, α-, neutron-, and photon-induced reactions, coupled with radioactive decay. The advent of radioactive ion beam facilities has opened an important new avenue for studying these processes, as many involve radioactive species. Nuclear physics also plays an important role in neutron stars: both the nuclear equation of state and cooling processes involving neutrino emission play a very important role. Recent developments and also the interplay between nuclear physics and astrophysics will be highlighted.

The field of relativistic heavy ion physics has seen significant advancement in the new millennium toward a greater understanding of QCD at high temperatures with the commissioning and operation of the Relativistic Heavy Ion Collider (RHIC) starting in 2000. Here we review progress in the field as presented in a set of lectures at the Lake Louise Winter Institute on Fundamental Interactions in February 2004.

In these three lectures the basic ideas and of the subject and some current issues are presented, but no attempt is made to teach calculational techniques and methods. (There is a significant overlap in the material here with my earlier lectures presented at the 2002 European Summer School.)

The results of two recent measurements at Belle on the CKM parameter ϕ₃ are presented. The analyses are based on the data sample of 152 million .

DØ has performed several searches for new phenomena on approximately 100 pb^-1 of interactions at . Results of searches for large extra dimensions, Z', leptoquarks, and SUSY are presented.

Searches for lepton flavour violating τ → 1ll and τ → lγ decays at the B-factories are presented. Upper limits on the branching ratios are obtained ~ O(10^-7) at 90% confidence level.

Measurements of a variety of hadron species in Au + Au collisions at 200 GeV by the STAR experiment are used to investigate properties of such collisions. We present a study of particle yields and transverse momentum spectra within the framework of chemical and local kinetic equilibrium models. The extracted freeze-out properties are studied as function of collision centrality. Those properties together with inferred initial conditions provide insights about collision dynamics at RHIC.

Inclusive photoproduction cross-sections of the neutral mesons η, ρ⁰, f₀(980) and f₂(1270) have been measured by H1 and compared to the photoproduction of π⁺ in ep collisions at HERA. Also, inclusive production and evidence for a narrow baryonic state decaying to have been observed by ZEUS at HERA.

Theories with extra space dimensions aiming at resolving the hierarchy problem have recently been developed. These scenarios have provided exciting new grounds for experimental probes. A review of some recent studies done by the ATLAS Collaboration on the sensitivity of the detector to various extra dimension models is reported in this document.

The physics potential for Higgs boson discovery at CMS is reviewed, both in the standard model (SM) and in its minimal supersymmetric extension (MSSM).

Selected new results are presented from searches for new physics in ep-collisions by the ZEUS and H1 collaborations. Using final states with Deep Inelastic Scattering, limits have been set on contact interactions, extra dimensions, a quark radius. Examples of searches for exclusive final states are the observation of events with isolated leptons and large missing transverse momentum, and multi-lepton final states. Limits are shown for κ_tuγ, an anomalous photon coupling.

Recent BABAR results on electroweak penguin and leptonic decays are reviewed. In particular, the measurements of B → K^(*) l⁺l^- and the preliminary results on B → X_s l⁺l^- are presented. Also summarized are the preliminary limits on B⁺ → l⁺ν (l = e, μ) and .

In May of 2003, RHIC provided the first collisions of longitudinally polarized protons, at . We report on and discuss the results for the longitudinal spin asymmetry for π⁰ production, which is sensitive to the polarization of the gluons in the polarized protons.

The muon g-2 experiment at Brookhaven has now reached a precision of 0.5 parts per million, with the result a_μ = 0.001 165 920 8(6). The experiment measures a sum rule of known physics, comparing precise predictions from the Standard Model for the muon anomaly for the electromagnetic, strong, and weak interactions to the experimental measurement. In this talk I discuss our measurement, emphasizing the ideas, challenges, and solutions. The experimental uncertainty is still dominated by statistics, with a systematic error for the present measurement of μ^- at 0.3 ppm.

The Alpha Magnetic Spectrometer (AMS) is a cosmic ray (CR) experiment that will operate on the International Space Station for three years, measuring the particle spectra in the rigidity range from 0.2 GV to 2 TV. The AMS-02 detector will provide measurements with unprecedented statistics of the hadronic and leptonic cosmic rays, allowing for a better study of the Earth magnetosphere, of the solar system environment, of the solar system neighborhood, and of the galactic interstellar medium.

We report recent results on the properties of the X(3872) produced via the B⁺ → K⁺X(3872) decay process in the Belle detector. We present constraints on possible charmonium-state assignments for this particles.

Recent diffractive results from the H1 and ZEUS Collaborations are presented, including the newest measurements of the diffractive structure function, . Recent results in the production of exclusive final states in diffraction are also presented, namely, dijet and charm production.

Recent charm and beauty results from the H1 and ZEUS Collaborations are presented.

We describe recent measurements of the production cross section and the mass of the top quark from the DØ Collaboration.

The Randall Sundrum model (RS) ^1,2 has recently received much attention because it could provide a solution to the hierarchy problem by means of an exponential factor in a five dimensional non-factorizable metric. In the simplest version the RS model is based on a five dimensional universe^3,4,5,6,7,8. This scalar sector of the RS model is parametrized in terms of a dimensionless parameter ξ, of the Higgs and radion masses m_h, m_ϕ and the vacuum expectation value of the radion field Λ_ϕ. The presence in the Higgs radion sector of trilinear terms opens up the important possibility of ϕ → hh decay and h → ϕϕ. In this study we estimate the CMS discovery potential for the radion (ϕ) in two Higgs decay mode (ϕ → hh) with , and final states.

A brief review is given of parity violation in the cesium atom. The recent developments in atomic theory are summarized. It is now firmly established that there is agreement with the standard model.

Results from the Belle experiment related to the KM angle ϕ₁ are reported. These results include sin2ϕ₁ measurements using decays of neutral B meson via the , and processes.

All hadrons that were observed until recently could be classified as either quark-antiquark states (mesons) or three-quark states (baryons). However, QCD permits also hadrons with manifestly more complex structures, such as exotics with a five-quark structure. The results of a search for the Θ⁺ pentaquark in quasi-real photoproduction on deuterium at the HERMES experiment are presented. The decay mode was studied through the measurement of the invariant mass spectrum. A |S| = 1 baryon state was observed as a peak in the invariant mass spectrum at 1528 ± 2.6(stat) ± 2.1(syst) MeV. The width is dominated by the experimental resolution.

We show that LSG model predictions of event ratios are clearly distinguished from those of the SM. This is true in all models of ultrahigh energy (UHE) neutrino sources, in both ν_e : ν_μ : ν_τ = 1 : 1 : 1 and ν_e : ν_μ : ν_τ = 1 : 2 : 0 scenarios for the flux incident on earth. In particular the ratios of upward μ events to upward shower events and the ratios of up events to down events are different by a factor of 2 to an order of magnitude in the comparisons between SM and LSG. ν_τ rates are low but show high sensitivity to SM vs LSG interaction physics.

PeV neutrinos produce particle showers when they interact with the atomic nuclei in ice. We briefly describe characteristics of these showers and the radio Cherenkov signal produced by the showers. We study pulses from electromagnetic (em), hadronic, and combined em-hadronic showers and propose extrapolations to EeV energies.

This talk reviews physics related to the muon decay parameter P_μξ, whose current measured value of 1.003 ± 0.008 will be improved by TWIST to a final accuracy about an order of magnitude better. The status of analysis of systematic uncertainties in the measurement of P_μξ is presented.

The seesaw theory, the leading theory for particle interactions, provides a viable mechanism for generating the matter-antimatter asymmetry of the universe. Testing its leptogenesis mechanism directly requires measurement of the d = 6 operator of the low-energy effective Lagrangian, in addition to the more familiar d = 5 operator which generates Majorana masses for the light neutrinos when the electroweak symmetry is spontaneously broken.

The RHIC offers new opportunities to study perturbative quantum chromodynamics. We can learn production of the high p_T hadrons and the heavy flavour in the forward and backward rapidity from the single muon analysis in PHENIX. Developement of new techniques to separate hadrons, decay muons, and prompt muons, makes the measurement possible. As a snap shot of the current progress, we report nuclear modification factor R_cp with high p_T hadrons.

The 8π Gamma-Ray Spectrometer, operating at TRIUMF in Vancouver Canada, is a high-precision instrument for detecting the decay radiations from exotic nuclei. In 2003, a new beta-scintillating array called SCEPTAR was installed within the 8π Spectrometer. With these two systems, precise measurements of half-lives and branching ratios can be made, specifically on certain nuclei which exhibit Superallowed Fermi 0⁺ → 0⁺ β-decay. These data can be used to determine the value of δ_C, an isospin symmetry-breaking (Coulomb) correction factor to good precision. As this correction factor is currently one of the leading sources of error in the unitarity test of the CKM matrix, a precise determination of its value could help to eliminate any possible "trivial" explanation of the seeming departure of current experimental data from Standard Model predictions.

The measurement of the inclusive jet cross-section at is compared to NLO QCD predictions and to Run 1 data. Results on single diffractive di-jet production are also presented as an example of the CDF forward physics program.

J/ψ production from nuclei is a sensitive probe of the gluon structure function and its modification in nuclei. It is also a leading signal for the creation of hot-dense matter in heavy-ion collisions. At RHIC, gluons are probed that lie deep in the shadowing region. Leading models of gluon shadowing predict suppressions of J/ψ production in nuclei that differ by as much as a factor of three. Data from PHENIX during the recent d-Au and companion p-p runs allow us to explore the level of gluon shadowing and other nuclear effects such as absorption. These measurements also serve as a baseline for the upcoming results from the high-luminosity Au-Au run and must be understood in order to look for effects beyond what is expected from cold nuclear matter, such as the creation of a Quark Gluon Plasma. PHENIX has reconstructed over 2000 J/ψ's detected via their decays into both e⁺e^- and μ⁺μ^-, covering rapidities between -2.2 and +2.4 for both p-p and d-Au collisions at . The nuclear dependence of J/ψ production versus rapidity, p_T, and impact parameter are obtained by comparison of the d-Au and p-p data. These results are compared to lower energy p-A results from Fermilab and to theoretical models.

TWIST, the TRIUMF Weak Interaction Symmetry Test, measures simultaneously the muon decay parameters ρ, δ, and P_μξ. The ultimate goal of the experiment is to determine each of these parameters to a few parts in 10⁴. With this precision, TWIST will confront several proposed extensions to the Standard Model. Decay event rates of several kHz allow for the collection of very large data samples, making TWIST a systematics-dominated experiment. Data are being analyzed at present that are expected to provide intermediate results for ρ and δ at ~ 10^-3. In this article, the basic physics of muon decay is shown, the TWIST detector is described, our blind analysis technique is explained briefly, and the techniques used to estimate our systematic uncertainties are discussed.

The see-saw mechanism of neutrino mass generation, when incorporated in supersymmetric theories with supergravity mediated supersymmetry breaking, results in low-energy lepton-flavour violation arising from the soft supersymmetry breaking slepton masses. The parameter space of supergravity theories with conserved R-parity is severely constrained by the requirement that the LSP provide cold dark matter with a relic density in the range indicated by the recent WMAP measurements, as well as by laboratory constraints. We calculate the μ → eγ branching ratio for the constrained minimal supersymmetric standard model, over the range of parameters consistent with WMAP and laboratory constraints, in families of see-saw model parameterizations which fit the low energy neutrino measurements. We find that over much of the range of see-saw models, for supersymmetry parameters consistent with WMAP and laboratory bounds, the resulting predicted rates for μ → eγ (and other charged lepton flavour violating processes) are within current experimental limits, but that these rates should be detectable with the next generation of lepton-flavour violation experiments.

The LEP measurements of charged current triple gauge couplings are described using the three sensitive processes e⁺e^- → W⁺W^-, e⁺e^- → Weν_e and . The measurements agree well with the Standard Model (SM) predictions and confirm the non-Abelian structure of the electroweak sector of the SM. The LEP search for anomalous neutral current triple gauge couplings is also presented but no deviations from the SM predictions are found.

It has been long believed that the interior of a neutron star consists of a neutron superfluid and a proton Type II superconductor. However, as has been recently shown by Link, long period precession of neutron stars indicates that this picture may be incorrect. In this talk, I will demonstrate a mechanism through which neutron stars could be Type I rather than Type II superconductors. Such a mechanism is due to the previously ignored strong interaction between proton and neutron cooper pairs. Type I proton superconductivity may allow for long period precession, as it implies that the magnetic field penetrates the neutron star in an array of normal domains, instead of magnetic flux tubes as has been previously assumed.

We demonstrate the potential of forthcoming μ → eγ and μ - e conversion experiments to implicate or disfavor leading solutions to the gauge hierarchy problem. Measurements of these exotic muon decays may have compelling implications for supersymmetric solutions. This is an abbreviation of pre-print hep-ph/0401170.¹

The existence of the top quark, discovered by CDF and DØ in 1995, has been re-established in the burgeoning dataset being collected in Run 2 of the Tevatron at Fermilab. Results from CDF on the top quark production cross section and top quark mass are consistent with the Standard Model expectations. The well-characterized top data samples will make it possible in the future to probe further for new physics in the top quark sector.

The analysis of anisotropic flow of particles created in high energy heavy-ion collisions gives insight into the early stage of these reactions. Measurements of directed flow (v₁), elliptic flow (v₂) and flow of 4^th and 6^th order (v₄ and v₆) are presented. While the study of v₂ for multi-strange particles establishes partonic collectivity the results for higher order anisotropies constrain the initial conditions of hydrodynamic model calculations.

The notoriously elusive CKM angle γ has recently been subject of several analysis. The advantages and challenges of the various methods are discussed and the results from the BABAR experiment are presented.

I report on a new measurement of the CKM matrix element |V_ub| from inclusive semileptonic decays of the B meson to final states that contain a u (but not a c) quark. This measurement uses a novel reconstruction method based on simulated annealing. I report also on a new measurement of photon energy spectrum in inclusive radiative decays of the B meson to final states containing the s quark.

Several methods to extract the strong coupling constant α_s by means of highly energetic jets in Deep-Inelastic Scattering are presented. The results from the various methods agree with one another and with the world average. The errors are competetive to those achieved in α_s determinations in other processes such as proton–anti-proton scattering.

We report results from the BABAR Collaboration on the semileptonic B decays, highlighting the measurements of the magnitude of the Cabibbo-Kobayashi-Maskawa matrix elements V_ub and V_cb. We describe the techniques used to obtain the matrix element |V_cb| using the measurement of the inclusive B → X_cℓν process and a large sample of exclusive B → D*ℓν decays. The |V_ub| matrix elements has been measured studying the hadronic mass distribution M_X and the lepton spectra at the endpoint for the B → X_uℓν process.

We investigate the spin and chiral dynamics of a high-energy massive neutrino propagating in a Schwarzschild space-time background described in terms of isotropic spherical co-ordinates. Employing the Cini-Touschek transformation, we derive an ultrarelativistic form of the Dirac Hamiltonian in curved space-time to compute the helicity and chirality transition rates to first-order in the neutrino's rest mass. We show that, under general conditions, the chirality transition rate is dependent on the zeroth-order component of the helicity transition rate. Further, we demonstrate that Schwarzschild space-time can distinguish between the helicity and chirality of neutrinos in the massless limit, which suggests that their equivalence for massless spin-1/2 particles is broken by the presence of a gravitational field.

We present a determination of a new class of Feynman diagrams relevant for second-order QCD corrections to the top quark decay t → bW. Modern computing techniques allow us to perform a reduction of the original loop integrals to master integrals. We obtain the analytical value of the top decay rate as an expansion around the limit of massless b and W.

W mass and width measurements performed at LEP are presented. The currently available LEP results are combined to yield: M_W= 80.412 ± 0.042 GeV, Γ_W= 2.150 ± 0.091 GeV. The analysis methods and the various uncertainties are illustrated and discussed. The results are compared with other measurements and the Standard Model prediction. An outlook for the future is given.

No abstract received.

We report the first observation of CP-violating asymmetries in B⁰ → π⁺π^- decays in the Belle detector.

The DØ experiment has been collecting data from collisions at a center-of-mass energy of 1.96 TeV at the Tevatron at Fermilab. In this paper, the latest electroweak results from DØ are summarized. Results are based on ~ 100 pb^-1 of data. Focus is on cross section measurements of W and Z bosons, their ratio R, and high mass di-EM events.

Single t quark production via four fermion contact interactions associated to flavour changing neutral currents was searched for in the data taken by the DELPHI detector at LEP2. The analysed data were accumulated at centre-of-mass energies ranging from 189 to 209 GeV with an integrated luminosity of 597.9 pb^-1. No evidence for a signal was found. Limits on the characteristic energy scale Λ were set for several coupling scenarios.

Review of recent CDF beauty physics results on CP violation, B mixing, lifetimes, masses and FCNC rare decays. Most of the studies use a reduced portion of the physics quality sample of about 250 pb^-1 collected from March 2001 to February 2004.

Preliminary results on fermion pair and photon pair production at LEP2 are presented, for which the measurements of the four LEP collaborations have been combined. This allows precise tests of the Standard Model (SM) at the ≈ 1% level. From the observed agreement with the SM predictions limits are derived for physics beyond the SM like contact interactions, models with additional Z' bosons and such with gravity in extra dimensions.

Inclusive W and Z production cross-sections have been measured by CDF and certain electroweak parameters extracted with high precision from these measurements. New results on diboson production at the Tevatron are also presented.

The Standard Model allows CP violation in non-leptonic weak decays of hyperons. The HyperCP collaboration¹ is performing a precision search for CP violation in hyperon decays. These decays are sensitive to sources of CP violation that neutral-meson decays are not. The measured CP observable is proportional to the difference between the product of the Ξ^- and Λ decay α parameters and that of the CP-conjugate decays. Preliminary results are presented from a fraction of the data.

The MINOS experiment¹ is in the final stage of construction and is expected to begin data collection early in 2005. The far detector has been assembled and is currently observing atmospheric neutrino events. Assembly of the near detector has begun and is expected to be complete by late 2004. An overview of the project will be presented.

The ANTARES collaboration has started the construction of a submarine neutrino telescope in the Mediterranean Sea. This detector will consist of a three-dimensional array of photomultipliers (PMTs), which will detect the Cherenkov light emitted by muons produced by high energy neutrino interactions. The scientific aims of the project include astrophysics, dark matter and neutrino oscillations. The project, which began in 1996, has carried out an intense R&D effort, including important milestones such as the "Demonstrator Line", which has shown the feasibility of the project, and the deployment of the electro-optical cable which links the detector to shore. These successful steps led, in 2003, to the deployment of a prototype line (1/5 of a full line) and of an instrumentation line (equipped with calibration devices), whose analysis of the first data will be presented.

LIST OF PARTICIPANTS.