121677266
HIGH-ENERGY gamma-RAY SOURCE FROM ELECTRON POSITRON PAIR ANNIHILATION
121983457
Pair Production and Bremsstrahlung of Charged Leptons
Photo pair productions of electrons, muons, and heavy leptons and bremsstrahlung of electrons and muons are reviewed. Atomic and nuclear form factors necessary for these calculations are discussed. Straggling of electrons in matter and other sects due to 6nite target thickness are considered. Tables of radiation lengths of all materials and the energy dependence of photon absorption coefFicients of many materials are presented. Problems associated with production of particles by photon and electron beams are also discussed.
118138915
DEPOLARIZATION OF SPIN 1/2 PARTICLES BY ELECTROMAGNETIC SCATTERING
16522997
RADIATIVE CORRECTIONS TO e+e- REACTIONS TO ALL ORDERS IN a USING THE RENORMALIZATION GROUP*
Renormalization group technique is used to improve the accuracy of the lowest order radiative corrections in QED. The exponentiation of infrared terms comes automatically. It also leads to exponentiation of the vertex functions. It predicts the -existence of conversion of photons into pairs and the result agrees with the Kroll-Wada relation. Kinoshita-Lee-Nauenberg cancellation of mass singularities occurs to all order in Q in leading log approximation in the final state if we sum over all the final states. Higher order corrections to the order o3 asymmetry is shown to be small. The results are used to derive useful formulas for the radiative corrections to processes such zas e+e+ p+p-, e+e--+ ~+~~~, e+e+ hadroqcontinuum, e+eT ---) very narrow ; -resonance such as $, and e+e+ not very narrow resonance such as ZO. .^ -_ . Submitted to Review of Modern Physics and Presented at the Asia Pacific Physics Conference Singapore, June 12-18, 1983 l Work supported by the Department of Energy, contract DEAC03-76SFOO515.
13561911
Addendum to the test of CP violation in Tau decay
We discuss the test of CP and CPT violation in τ decay without using the polarized electron beam by comparing partial fractions of τ− and τ+ decay into channels with strong final state interactions. For example, Γ(τ−→π−+π0+ν)≠Γ(τ+→π++π0+ν) signifies violation of CP. The optimum energy to investigate CP violation in τ decay is discussed. We conclude that this energy is a few MeV below ψ(2s) in order to avoid the charm contribution and over abundance of hadrons at the ψ(2s) peak.
2397140
Search for new mechanism of CP violation through tau decay and semileptonic decay at hadrons
If CP is violated in any decay process involving leptons it will signify the existence of a new force (called the X boson) responsible for CP violation that may be the key to understanding matter-antimatter asymmetry in the universe. The author discusses the signatures of CP violation in (1) the decay of tau lepton, and (2) the semileptonic decay of {pi}, K, D, B and t particles by measuring the polarization of the charged lepton in the decay. The author discusses how the coupling constants and their phases of the coupling of the X boson to 9 quark vertices and 3 lepton vertices can be obtained through 12 decay processes.
119194201
Global Study of the Simplest Scalar Phantom Dark Matter Model
We present a global study of the simplest scalar phantom dark matter model. The best fit parameters of the model are determined by simultaneously imposing (i) relic density constraint from WMAP, (ii) 225 live days data from direct experiment XENON100, (iii) upper limit of gamma-ray flux from Fermi-LAT indirect detection based on dwarf spheroidal satellite galaxies, and (iv) the Higgs boson candidate with a mass about 125 GeV and its invisible branching ratio no larger than 40% if the decay of the Higgs boson into a pair of dark matter is kinematically allowed. The allowed parameter space is then used to predict annihilation cross sections for gamma-ray lines, event rates for three processes mono-b jet, single charged lepton and two charged leptons plus missing energies at the Large Hadron Collider, as well as to evaluate the muon anomalous magnetic dipole moment for the model.
118097234
Shedding Light on Dark Matter with Fermi LAT Data on Gamma Rays
The Andrzej Soltan Institute for Nuclear Studies, Warsaw, Poland(Dated: September 9, 2009)The diﬀuse Galactic γ–ray data from the region of the Galactic Center has been collected by theLAT instrument on the Fermi Gamma-Ray Space Telescope. In this paper we argue that it may beable to provide an unambiguous evidence of originating, in addition to known astrophysical sources,from dark matter annihilations in the halo, independently of the mass and other properties of thedark matter particle. We also show that the recently released high precision data from mid-latitudesis already providing an upper bound, albeit still a weak one, on the cuspiness of the dark matterdensity proﬁle as a function of the mass of the dark matter assumed to be a stable neutralino ofminimal supersymmetry.I. INTRODUCTION
119226535
LEP shines light on dark matter
Dark matter pair production at high energy colliders may leave observable signatures in the energy and momentum spectra of the objects recoiling against the dark matter. We use LEP data on mono-photon events with large missing energy to constrain the coupling of dark matter to electrons. Within a large class of models, our limits are complementary to and competitive with limits on dark matter annihilation and on WIMP-nucleon scattering from indirect and direct searches. Our limits, however, do not suer from systematic and astrophysical uncertainties associated with direct and indirect limits. For example, we are able to rule out light (. 10 GeV) thermal relic dark matter with universal couplings exclusively to charged leptons. In addition, for dark matter mass below about 80 GeV, LEP limits are stronger than Fermi constraints on annihilation into charged leptons in dwarf spheroidal galaxies. Within its kinematic reach, LEP also provides the strongest constraints on the spin-dependent direct detection cross section in models with universal couplings to both quarks and leptons. In such models the strongest limit is also set on spin independent scattering for dark matter masses below 4 GeV. Throughout our discussion, we consider both low energy eective theories of dark matter, as well as several motivated renormalizable scenarios involving light mediators.
51428350
Soft RPV through the baryon portal
A bstractSupersymmetric (SUSY) models with R-parity generically predict sparticle decays with invisible neutralinos, which yield distinctive missing energy events at colliders. Since most LHC searches are designed with this expectation, the putative bounds on sparticle masses become considerably weaker if R-parity is violated so that squarks and gluinos decay to jets with large QCD backgrounds. Here we introduce a scenario in which baryonic R-parity violation (RPV) arises effectively from soft SUSY breaking interactions, but leptonic RPV remains accidentally forbidden to evade constraints from proton decay and FCNCs. The model features a global R-symmetry that initially forbids RPV interactions, a hidden R-breaking sector, and a heavy mediator that communicates this breaking to the visible sector. After R-symmetry breaking, the mediator is integrated out and an effective RPV A-term arises at tree level; RPV couplings between quarks and squarks arise only at loop level and receive additional suppression. Although this mediator must be heavy compared to soft masses, the model introduces no new hierarchy since viable RPV can arise when the mediator mass is near the SUSY breaking scale. In generic regions of parameter space, a light thermally-produced gravitino is stable and can be a viable dark matter candidate.
122379517
Infrared Constraints On Ultraviolet Theories