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Frank Wilczek

Publications and source records attributed to Frank Wilczek.

At least 163 records · Page 9Linked to original sources
arXiv2000

Prospects for Indirect Detection of Neutralino Dark Matter

Dark matter candidates arising in models of particle physics incorporating weak scale supersymmetry may produce detectable signals through their annihilation into neutrinos, photons, or positrons. A large number of relevant experiments are planned or underway. The `logically possible' parameter space is unwieldy. By working in the framework of minimal supergravity, we can survey the implications of the experiments for each other, as well as for direct searches, collider searches, low-energy experiments, and naturalness in a transparent fashion. We find that a wide variety of experiments provide interesting probes. Particularly promising signals arise in the mixed gaugino-Higgsino region. This region is favored by low-energy particle physics constraints and arises naturally from minimal supergravity due to the focus point mechanism. Indirect dark matter searches and traditional particle searches are highly complementary. In cosmologically preferred models, if there are charged superpartners with masses below 250 GeV, then some signature of supersymmetry must appear before the LHC begins operation.

astro-ph↗
arXiv2000

Neutralino Dark Matter in Focus Point Supersymmetry

In recent work, it has been argued that multi-TeV masses for scalar superpartners are not unnatural. Indeed, they appear to have significant phenomenological virtues. Here we explore the implications of such `focus point' supersymmetry for the dark matter problem. We find that constraints on relic densities do not place upper bounds on neutralino or scalar masses. We demonstrate that, in the specific context of minimal supergravity, a cosmologically stable mixed gaugino-Higgsino state emerges as an excellent, robust dark matter candidate. We estimate that, over a wide range of the unknown parameters, the spin-independent proton-neutralino cross sections fall in the range accessible to planned search experiments.

hep-ph↗
arXiv2000

QCD In Extreme Conditions

Recently we have made considerable progress in our understanding of the behavior of QCD in extreme conditions of high temperature or large baryon number density. Among the highlights are the prediction of a well-characterized true critical point, and the discovery that the ground state of three-flavor QCD at asymptotically high densities exhibits color-flavor locking. The critical point occurs at the unique temperature and density where a sharp distinction between an ionized plasma of quarks and gluons and the hadronic phase first appears. It appears to be accessible both to numerical and to laboratory experiments. Color-flavor locking provides a calculable, weak-coupling realization of confinement and chiral symmetry breaking. It also provides a microscopic realization of Han-Nambu charge assignments for quark quasiparticles, and of Yang-Mills theory for the physical vector mesons. Here I provide a self-contained introduction to these developments.

hep-ph↗
arXiv2000

Radical Conservatism and Nucleon Decay

Unification of couplings, observation of neutrino masses in the expected range, and several other considerations confirm central implications of straightforward gauge unification based on SO(10) or a close relative and incorporating low-energy supersymmetry. The remaining outstanding consequence of this circle of ideas, yet to be observed, is nucleon instability. Clearly, we should aspire to be as specific as possible regarding the rate and form of such instability. I argue that not only esthetics, but also the observed precision of unification of couplings, favors an economical symmetry-breaking (Higgs) structure. Assuming this, one can exploit its constraints to build reasonably economical, overconstrained yet phenomenologically viable models of quark and lepton masses. Putting it all together, one arrives at reasonably concrete, hopeful expectations regarding nucleon decay. These expectations are neither ruled out by existing experiments, nor hopelessly inaccessible.

hep-ph↗
arXiv2000

Global Structure of Evaporating Black Holes

By extending the charged Vaidya metric to cover all of spacetime, we obtain a Penrose diagram for the formation and evaporation of a charged black hole. In this construction, the singularity is time-like. The entire spacetime can be predicted from initial conditions if boundary conditions at the singularity are known.

gr-qc↗
arXiv1999

Charged stripes from alternating static magnetic field

We motivate and perform a calculation of the energy of a cold fluid of charged fermions in the presence of a striped magnetic background. We find that a non-trivial value for the doping density on the walls is preferred

cond-mat.str-el↗
arXiv1999

Minimal Potentials with Very Many Minima

We demonstrate, by construction, that simple renormalizable matrix potentials with S_N, as opposed to O(N), symmetry can exhibit an exponentially large number of inequivalent deep local minima.

cond-mat↗
arXiv1999

Superconductivity from perturbative one-gluon exchange in high density quark matter

We study color superconductivity in QCD at asymptotically large chemical potential. In this limit, pairing is dominated by perturbative one-gluon exchange. We derive the Eliashberg equation for the pairing gap and solve this equation numerically. Taking into account both magnetic and electric gluon exchanges, we find $Δ\sim g^{-5}\exp(-c/g)$ with $c=3π^2/\sqrt{2}$, verifying a recent result by Son. For chemical potentials that are of physical interest, $μ< 1$ GeV, the calculation ceases to be reliable quantitatively, but our results suggest that the gap can be as large as 100 MeV.

hep-ph↗
arXiv1999

The Recent Excitement in High-Density QCD

Over the past few months, the theory of QCD at high density has been advanced considerably. It provides new perspectives on, and controlled realizations of, confinement and chiral symmetry breaking. Here I survey the recent developments, and suggest a few directions for future work.

hep-ph↗
arXiv1999

Fermion masses, neutrino oscillations, and proton decay in the light of SuperKamiokande

Within the framework of unified gauge models, interactions responsible for neutrino masses can also provide mechanisms for nucleon instability. We discuss their implications concretely in the light of recent results on neutrino oscillation from the SuperKamiokande collaboration. We construct a predictive SO(10)-based framework that describes the masses and mixing of all quarks and leptons. An overconstrained global fit is obtained, that makes five successful predictions for quarks and charged leptons. The same description provides agreement with the SuperK results on atmospheric neutrinos and supports a small-angle MSW mechanism. We find that current limits on nucleon stability put significant stress on the framework. Further, a distinctive feature of the SO(10) model developed here is the likely prominence of the $μ^+ K^0$ mode in addition to the $\barν K^+$ mode of proton decay. Thus improved searches in these channels for proton decay will either turn up events, or force us outside this circle of ideas.

hep-ph↗
arXiv1999

Quark Description of Hadronic Phases

We extend our proposal that major universality classes of hadronic matter can be understood, and in favorable cases calculated, directly in the microscopic quark variables, to allow for splitting between strange and light quark masses. A surprisingly simple but apparently viable picture emerges, featuring essentially three phases, distinguished by whether strangeness is conserved (standard nuclear matter), conserved modulo two (hypernuclear matter), or locked to color (color flavor locking). These are separated by sharp phase transitions. There is also, potentially, a quark phase matching hadronic K-condensation. The smallness of the secondary gap in two-flavor color superconductivity corresponds to the disparity between the primary dynamical energy scales of QCD and the much smaller energy scales of nuclear physics.

hep-ph↗
arXiv1998

Continuity of Quark and Hadron Matter

We review, clarify, and extend the notion of color-flavor locking. We present evidence that for three degenerate flavors the qualitative features of the color-flavor locked state, reliably predicted for high density, match the expected features of hadronic matter at low density. This provides, in particular, a controlled, weak-coupling realization of confinement and chiral symmetry breaking in this (slight) idealization of QCD.

hep-ph↗
arXiv1998

CP Violation, Higgs Couplings, and Supersymmetry

Supersymmetric extensions of the standard model generically contain additional sources of CP violation. We discuss how at one loop a potentially large CP violating coupling of the lightest Higgs, h^0, to leptons is induced in the minimal supersymmetric standard model (MSSM). The CP violating couplings of h^0 in extensions of the MSSM, such as the next-to-minimal supersymmetric standard model (NMSSM) are also considered. We indicate how this CP violation might be observed; in particular a polarization-dependent production asymmetry, in the context of a muon collider, provides a means to access this coupling cleanly. In the MSSM, existing limits on the electric dipole moment (EDM) of the electron, coupled with standard universality assumptions, severly constrains any such signal. Nevertheless, extensions of the MSSM, such as the NMSSM, allow CP-violating signals as large as 100%.

hep-ph↗
arXiv1998

High Density Quark Matter and the Renormalization Group in QCD with two and three flavors

We consider the most general four fermion operators in QCD for two and three massless flavors and study their renormalization in the vicinity of the Fermi surface. We show that, asymptotically, the largest coupling corresponds to scalar diquark condensation. Asymptotically the direct and iterated (molecular) instanton interactions become equal. We provide simple arguments for the form of the operators that diagonalize the evolution equations. Some solutions of the flow equations exhibit instabilities arising out of purely repulsive interactions.

hep-ph↗
arXiv1998

Beyond The Standard Model: This Time for Real

The value of the neutrino mass reported by the SuperK collaboration fits beautifully into the framework of gauge theory unification. Here I justify this claim, and review the other main reasons to believe in that framework. Supersymmetry and SO(10) symmetry are important ingredients; nucleon instability is a dramatic consequence.

hep-ph↗
arXiv1998

Projective Statistics and Spinors in Hilbert Space

In quantum mechanics, symmetry groups can be realized by projective, as well as by ordinary unitary, representations. For the permutation symmetry relevant to quantum statistics of N indistinguishable particles, the simplest properly projective representation is highly non-trivial, of dimension $2^{(N-1)/2}$, and is most easily realized starting with spinor geometry. Quasiparticles in the Pfaffian quantum Hall state realize this representation. Projective statistics is a consistent theoretical possibility in any dimension.

hep-th↗
arXiv1998

From Notes to Chords in QCD

After a very brief overview recollecting the `classic' parts of QCD, that is its application to describe hard processes and static properties of hadrons, I survey recent work -- some very recent -- on QCD at non-zero temperature and density. At finite temperature and zero density there is a compelling theoretical framework allowing us to predict highly specific, non-trivial dependence of the phase structure on the number of flavors and colors. Several aspects have been rigorously, and successfully, tested against massive numerical realizations of the microscopic theory. The theoretical description of high density is nowhere near as mature, but some intriguing possibilities have been put forward. The color/flavor locked state recently proposed for three flavors has many remarkable features connected to its basic symmetry structure, notably including chiral symmetry re-breaking and the existence (unlike for two flavors) of a gauge invariant order parameter. I survey potential applications to heavy ion collisions, astrophysics, and cosmology. A noteworthy possibility is that stellar explosions are powered by release of QCD latent heat.

hep-ph↗