arXiv subjects

Michael E. Peskin

Publications and source records attributed to Michael E. Peskin.

83 records · Page 5Linked to original sources

arXiv1997

Duality in Supersymmetric Yang-Mills Theory

These lectures provide an introduction to the behavior of strongly-coupled supersymmetric gauge theories. After a discussion of the effective Lagrangian in nonsupersymmetric and supersymmetric field theories, I analyze the qualitative behavior of the simplest illustrative models. These include supersymmetric QCD for $N_f < N_c$, in which the superpotential is generated nonperturbatively, N=2 SU(2) Yang-Mills theory (the Seiberg-Witten model), in which the nonperturbative behavior of the effective coupling is described geometrically, and supersymmetric QCD for N_f large, in which the theory illustrates a non-Abelian generalization of electric-magnetic duality. [Lectures presented at the 1996 TASI Summer School, to appear in the proceedings.]

hep-th↗

arXiv1996

Physics Opportunities of e+e- Linear Colliders

We describe the anticipated experimental program of an e+e- linear collider in the energy range 500 GeV -- 1.5 TeV. We begin with a description of current collider designs and the expected experimental environment. We then discuss precision studies of the W boson and top quark. Finally, we review the range of models proposed to explain the physics of electroweak symmetry breaking and show, for each case, the central role that the linear collider experiments will play in elucidating this physics. (to appear in Annual Reviews of Nuclear and Particle Science)

hep-ex↗

arXiv1996

The Experimental Investigation of Supersymmetry Breaking

If Nature is supersymmetric at the weak interaction scale, what can we hope to learn from experiments on supersymmetric particles? The most mysterious aspect of phenomenological supersymmetry is the mechanism of spontaneous supersymmetry breaking. This mechanism ties the observable pattern of supersymmetric particle masses to aspects of the underlying unified theory at very small distance scales. In this article, I will discuss a systematic experimental program to determine the mechanism of supersymmetry breaking. Both $pp$ and $e^+e^-$ colliders of the next generation play an essential role. [Lecture presented at the 1995 Yukawa International Symposium (YKIS`95), to appear in the proceedings.]

hep-ph↗

arXiv1995

Duality and other Exotic Gauge Dynamics in Softly Broken Supersymmetric QCD

We analyze the theory of softly broken supersymmetric $QCD$. Exotic behavior like spontaneously broken baryon number, massless composite fermions and Seiberg's duality seems to persist also in the presence of (small) soft supersymmetry breaking. We argue that certain, specially tailored, lattice simulations may be able to detect the novel phenomena. Most of the exotic behavior does not survive the decoupling limit of large SUSY breaking parameters.

hep-th↗

arXiv1995

Exotic Non-Supersymmetric Gauge Dynamics from Supersymmetric QCD

We extend Seiberg's qualitative picture of the behavior of supersymmetric QCD to nonsupersymmetric models by adding soft supersymmetry breaking terms. In this way, we recover the standard vacuum of QCD with $N_f$ flavors and $N_c$ colors when $N_f < N_c$. However, for $N_f \geq N_c$, we find new exotic states---new vacua with spontaneously broken baryon number for $N_f = N_c$, and a vacuum state with unbroken chiral symmetry for $N_f > N_c$. These exotic vacua contain massless composite fermions and, in some cases, dynamically generated gauge bosons. In particular Seiberg's electric-magnetic duality seems to persist also in the presence of (small) soft supersymmetry breaking. We argue that certain, specially tailored, lattice simulations may be able to detect the novel phenomena. Most of the exotic behavior does not survive the decoupling limit of large SUSY breaking parameters.

hep-th↗

arXiv1994

Violation of CPT and Quantum Mechanics in the K0--K0bar System

We reconsider the model of quantum mechanics violation in the $\ko$--$\kob$ system, due to Ellis, Hagelin, Nanopoulos, and Srednicki, in which \cp- and \cpt-violating signatures arise from the evolution of pure states into mixed states. We present a formalism for computing time-dependent asymmetries in this model and show that present data constrains its parameters significantly. In the future, this model will be put to very stringent tests at a $ϕ$ factory. We present the theory of these tests and show the relation between particular $ϕ$ decay correlations and the parameters of quantum mechanics violation.

hep-ph↗

arXiv1994

Complementarity of $e^+e^-$ and $pp$ Colliders for the Exploration of Electroweak Symmetry Breaking

I review the physics capabilities of the machines proposed for the next generation of high-energy experimentation: in hadron physics, the LHC, and in electron physics, a $500$--$1500$ GeV $e^+e^-$ linear collider. Using for illustration two specific models of electroweak symmetry breaking, I show how the $pp$ and $e^+e^-$ techniques are expected to complement one another in the exploration of the next scale of physics. [invited lecture at the 22nd INS Symposium, Tokyo] (text only; complete paper with figures and tables available by anonymous ftp from preprint.slac.stanford.edu, in the directory pub/preprints/hep-ph/9408)

hep-ph↗

arXiv1994

Spin, Mass, and Symmetry

This is a broad-brush introduction to the theory of spin in quantum field theory, presented at the 1993 SLAC Summer Institute. It may be useful for beginning students.

hep-ph↗

arXiv1993

Production, Decay, and Polarization of Excited Heavy Hadrons

We discuss the production via fragmentation of excited heavy mesons and baryons, and their subsequent decay. In particular, we consider the question of whether a net polarization of the initial heavy quark may be detected, either in a polarization of the final ground state or in anisotropies in the decay products of the excited hadron. The result hinges in part on a nonperturbative parameter which measures the net transverse alignment of the light degrees of freedom in the fragmentation process. We use existing data on charmed mesons to extract this quantity for certain excited mesons. Using this result, we estimate the polarization retention of charm and bottom baryons.

hep-ph↗

arXiv1993

Hadron production in gamma-gamma collisions as a background for e+e- linear colliders

Drees and Godbole have proposed that, at the interaction point of an e+e- linear collider, one expects a high rate of hadron production by gamma-gamma collisions, providing an additional background to studies in e+e- annihilation. Using a simplified model of the gamma-gamma cross section with soft and jet-like components, we estimate the expected rate of these hadronic events for a variety of realistic machine designs. The final background rates are quite small, and they become smaller still when viewed with a realistic detector simulation.

hep-ph↗

arXiv1993

Computation of Mini-Jet Inclusive Cross Sections

We apply the theory of parton-parton total cross sections at large ``s", due to Lipatov and collaborators, to compute the inclusive cross section for jets which accompany a large ``s" parton scattering process.

hep-ph↗