arXiv subjects
Publications and source records attributed to R. D. Peccei.
After discussing alternative scenarios for the origins of the electroweak symmetry breaking, I briefly review the experimental status of the Standard Model. I explore further both the hints for, and constraints on, supposing that that a supersymmetric extension of the Standard Model exists, with supersymmetry broken at the weak scale. I end with a few comments on the theoretical implications of the recent evidence for neutrino oscillations.
These lectures describe why one believes there is physics beyond the Standard Model and review the expectations of three alternative explanations for the Fermi scale. After examining constraints and hints for beyond the Standard Model physics coming from experiment, I discuss, in turn, dynamical symmetry breaking, supersymmetry and extra compact dimension scenarios associated with the electroweak breakdown.
In this overview, I discuss some of the open issues in Kaon physics. After briefly touching on lattice calculations of Kaon dynamics and tests of CPT, my main focus of attention is on epsilon prime over epsilon and on constraints on the CKM model. The impact of rare K- decays and of experiments with B-mesons for addressing the issue of CP-violation is also discussed. The importance of looking for signals of flavor-conserving CP violating phases is emphasized.
These lectures describe some aspects of the physics of massive neutrinos. After a brief introduction of neutrinos in the Standard Model, I discuss possible patterns for their masses. In particular, I show how the presence of a large Majorana mass term for the right-handed neutrinos can engender tiny neutrino masses for the observed neutrinos. If neutrinos have mass, different flavors of neutrinos can oscillate into one another. To analyze this phenomena, I develop the relevant formalism for neutrino oscillations, both in vacuum and in matter. After reviewing the existing (negative) evidence for neutrino masses coming from direct searches, I discuss evidence for, and hints of, neutrino oscillations in the atmosphere, the sun, and at accelerators. Some of the theoretical implications of these results are emphasized. I close these lectures by briefly outlining future experiments which will shed further light on atmospheric, accelerator and solar neutrino oscillations. A pedagogical discussion of Dirac and Majorana masses is contained in an appendix.
I review some of the salient issues connected to CP-violation and weak decays. In particular, I focus on recent and forthcoming tests of the CKM model and discuss the accuracy one can expect to achieve in B-decays for the parameters of this model.
This summary is organized into four parts. In the first section (News) I discuss the SuperKamiokande results on atmospheric neutrino oscillations, as well as recent results from cosmology. The second section (Refinements) focuses on electroweak tests, recent results in the flavor sector and in probing QCD, as well as searches for new particles. The third section (Mysteries) discusses issues associated with neutrino masses and mixings in more depth. Finally, in the last section (Hopes) I reflect on both the short and long term future of the field.
In these lectures I examine some of the principal issues in cosmology from a particle physics point of view. I begin with nucleosynthesis and show how the primordial abundance of the light elements can help fix the number of (light) neutrino species and determine the ratio $η$ of baryons to photon in the universe now. The value of $η$ obtained highlights two of the big open problems of cosmology: the presence of dark matter and the need for baryogenesis. After discussing the distinction between hot and cold dark matter, I examine the constraints on, and prospect for, neutrinos as hot dark matter candidates. I show next that supersymmetry provides a variety of possibilities for dark matter, with neutralinos being excellent candidates for cold dark matter and gravitinos, in some scenarios, possibly providing some form of warm dark matter. After discussing axions as another cold dark matter candidate, I provide some perspectives on the nature of dark matter before turning to baryogenesis. Here I begin by outlining the Sakharov conditions for baryogenesis before examining the issues and challenges of producing a, large enough, baryon asymmetry at the GUT scale. I end my lectures by discussing the Kuzmin-Rubakov-Shaposhnikov mechanism and issues associated with electrical baryogenesis. In particular, I emphasize the implications that generating the baryon asymmetry at the electroweak scale has for present-day particle physics.
I begin these lectures by examining the transformation properties of quantum fields under the discrete symmetries of Parity, P, Charge Conjugation, C, and Time Reversal, T. With these results in hand, I then show how the structure of the Standard Model helps explain the conservation/violation of these symmetries in various sectors of the theory. This discussion is also used to give a qualitative proof of the CPT Theorem, and some of the stringent tests of this theorem in the neutral Kaon sector are reviewed. In the second part of these lectures, global symmetries are examined. Here, after the distinction between Wigner-Weyl and Nambu-Goldstone realizations of these symmetries is explained, a discussion is given of the various, approximate or real, global symmetries of the Standard Model. Particular attention is paid to the role that chiral anomalies play in altering the classical symmetry patterns of the Standard Model. To understand the differences between anomaly effects in QCD and those in the electroweak theory, a discussion of the nature of the vacuum structure of gauge theories is presented. This naturally raises the issue of the strong CP problem, and I present a brief discussion of the chiral solution to this problem and of its ramifications for astrophysics and cosmology. I also touch briefly on possible constraints on, and prospects for, having real Nambu-Goldstone bosons in nature, concentrating specifically on the simplest example of Majorons. I end these lectures by discussing the compatibility of having global symmetry in the presence of gravitational interactions. Although these interactions, in general, produces small corrections, they can alter significantly the Nambu-Goldstone sector of theories.
I discuss how anomalies affect classical symmetries and how, in turn, the non-trivial nature of the gauge theory vacuum makes these quantum corrections troublesome. Although no solution seems in sight for the cosmological constant problem, I examine three possible approaches to the strong CP problem involving vacuum dynamics, an additional chiral symmetry, and the possibility of spontaneous CP or P breaking. All of these "solutions" have their own problems and suggest that, at a deep level, we do not understand the nature of CP violation. Nevertheless, it remains extremely important to search for experimental signals predicted by these theoretical "solutions", like invisible axions.
After outlining some of the issues surrounding the flavor problem, I present three speculative ideas on the origin of families. In turn, families are conjectured to arise from an underlying preon dynamics; from random dynamics at very short distances; or as a result of compactification in higher-dimensional theories. Examples and limitations of each of these speculative scenarios are discussed. The twin roles that family symmetries and GUT's can have on the spectrum of quarks and leptons is emphasized, along with the dominant role that the top mass is likely to play in the dynamics of mass generation.
We present an estimate of certain higher order corrections to the contribution of the charm triangle loop in the inclusive B -> X_s gamma decay rate, recently discussed by Voloshin. We find that these corrections are minute and hence the result found by Voloshin, although small, is quite robust.
These notes contain some of the material I presented at TASI 96 on the comparison of the standard model with precision electroweak data. After a physical accounting of the dominant electroweak radiative corrections, including the effects of initial state bremsstrahlung, I examine how data from LEP and the SLC provides a clear test of the standard model. Apparent discrepancies in the $R_b$ and $R_c$ ratios, and their physical resolution, are also examined in some detail.
The physical origin of the strong CP problem in QCD, rooted in the structures of the vacuum of the standard model, is reviewed. The chiral solution to this problem, with its accompanying axion, is explained and various characteristics of axions are detailed. Although visible axion models are excluded experimentally, models with very light and very weakly coupled axions are still tenable. The astrophysical and cosmological implications of such axion models are discussed, along with ongoing experimental attempts to detect such, so called, invisible axions.
We interpret the dijet enhancement reported by the ALEPH collaboration in the process $e^+e^- \rightarrow $ 4 jets as being due to the production of a pair of bottom squarks, followed by their R-parity violating decays into pairs of light quarks. Constraints on this speculative interpretation are examined. Some of the consequences of our hypothesis are drawn within the context of softly broken supersymmetry.
This summary discusses some of the topics which were of overarching interest at the Symposium. These included, corrections to perturbative QCD predictions; heavy quark physics; electroweak symmetry breaking; and physics of the top quark.
We introduce the idea of natural mass matrices, an organizing principle useful in the search for GUT scale quark mass matrix patterns that are consistent with known CKM constraints and quark mass eigenvalues. An application of this idea is made in the context of SUSY GUTs and some potentially ``successful'' GUT scale mass patterns are found. The CKM predictions of these patterns are presented and some relevant strong CP issues are discussed.
This review of CP violation focuses on the status of the subject and its likely future development through experiments in the Kaon system and with B-decays. Although present observations of CP violation are perfectly consistent with the CKM model, we discuss the theoretical and experimental difficulties which must be faced to establish this conclusively. In so doing, theoretical predictions and experimental prospects for detecting $ΔS=1$ CP violation through measurements of $ε^\prime/ε$ and of rare K decays are reviewed. The crucial role that B CP-violating experiments will play in elucidating this issue is emphasized . The importance of looking for evidence for non-CKM CP-violating phases, through a search for a non-vanishing transverse muon polarization in $K_{μ3}$ decays, is also stressed.
We study low energy experimental constraints on an anomalous top-quark coupling associated with the flavor-changing neutral current vertex $Z \bar t c$. In view of these constraints, we discuss the experimental observability of the induced rare decay mode $t \rightarrow Zc$, both at the Fermilab Tevatron (with the Main Injector or a luminosity-upgrade) and at the LHC.