121243747
Intermediate Boson Pair Production as a Means for Determining its Magnetic Moment
It is shown that, under the assumption of zero anomalous quadrupole moment, the photproduction of intermediate boson pairs on protons has a cross section that is very sensitive to the magnetic moment. The photoproduction cross section for intermediate boson pairs on iron is also calculated. (C.E.S.)
118138915
DEPOLARIZATION OF SPIN 1/2 PARTICLES BY ELECTROMAGNETIC SCATTERING
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.
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.
7044095
The investigation of CP violation through the decay of polarized tau leptons II
Under the assumption that CP violation is caused by exchange of anew boson, the authors propose to measure the magnitudes and CP-violating phases of the coupling constants of this boson to five different vertices in tau decay. This can be accomplished by studying the decay of polarized tau leptons produced at an e{sup +}e{sup {minus}} collider whose beams are polarized. These five coupling constants could be used to construct a future theory of CP violation. If CP is violated in any channel of tau decay, it will imply that there exists a new charged boson other than the W boson responsible for CP violation. It will also imply that CP violation is much more prevalent than the standard theory predicts and this may enable one to understand the preponderance of matter over antimatter in the present universe.
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.
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
18956502
Global fits of the Non-Universal Higgs Model
We examine the Non-Universal Higgs Model (NUHM) with the help of a Markov Chain Monte Carlo scanning technique and Bayesian statistics. The method allows us to reveal more fully the remarkably rich and complex structure of the model and also some new interesting features. In particular we find that, for large ranges of parameters, the neutralino dark matter in the model is higgsino-like with mass close to 1 TeV. This feature does depend to some extent on the prior but generically results from a mild focussing effect in the running of one of the Higgs masses that we also point out. On the other hand, the usual bino-like neutralino is also present, and in some sense is favored by a more robust prior and a better average chi–square. In spite of experimental constraints often favoring different regions of parameter space than in the Constrained MSSM, most observational consequences appear fairly similar, which will make it challenging to experimentally distinguish the two models.
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.
118555927
Global constraints on effective dark matter interactions: relic density, direct detection, indirect detection, and collider
An effective interaction approach is used to describe the interactions between the spin 0 or spin 1/2 dark matter particle and the degrees of freedom of the standard model. This approach is applicable to those models in which the dark matter particles do not experience the standard-model interactions, e.g., hidden-sector models. We explore the effects of these effective interaction operators on (i) dark matter relic density, (ii) spin-independent and spin-dependent dark matter-nucleon scattering cross sections, (iii) cosmic antiproton and gamma ray fluxes from the galactic halo due to dark matter annihilation, and (iv) monojet and monophoton production plus missing energy at the Tevatron and the Large Hadron Collider (LHC). We combine the experimental data of relic density from WMAP7, spin-independent cross section from XENON100, spin-dependent cross section from XENON10, ZEPLIN-III, and SIMPLE, cosmic antiproton flux from PAMELA, cosmic gamma-ray flux from Fermi-LAT, and the monojet and monophoton data from the Tevatron and the LHC, to put the most comprehensive limits on each effective operator.
122803295
Constrained next-to-minimal supersymmetric standard model with a 126 GeV Higgs boson: A global analysis
We present the first global analysis of the constrained next-to-minimal supersymmetric standard model that investigates the impact of the recent discovery of a 126 GeV Higgs-like boson, of the observation of a signal for branching ratio $\mathrm{BR}({\mathrm{B}}_{\mathrm{s}}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}})$, and of constraints on supersymmetry from $\ensuremath{\sim}5/\mathrm{fb}$ of data accumulated at the LHC, as well as of other relevant constraints from colliders, flavor physics and dark matter. We consider three possible cases, assuming in turn that the discovered Higgs boson is (i) the lightest Higgs boson of the model; (ii) the next-to-lightest Higgs boson; and (iii) a combination of both roughly degenerate in mass. The likelihood function for the Higgs signal uses signal rates in the $\ensuremath{\gamma}\ensuremath{\gamma}$ and $ZZ\ensuremath{\rightarrow}4l$ channels, while that for the Higgs exclusion limits assumes decay through the $\ensuremath{\gamma}\ensuremath{\gamma}$, $\ensuremath{\tau}\ensuremath{\tau}$, $ZZ$ and ${W}^{+}{W}^{\ensuremath{-}}$ channels. In all cases considered we identify the 68% and 95% credible posterior probability regions in a Bayesian approach. We find that, when the constraints are applied with their respective uncertainties, the first case shows strong CMSSM-like behavior, with the stau coannihilation region featuring highest posterior probability, the best-fit point, a correct mass of the lightest Higgs boson and the lighter top squark mass in the ballpark of 1 TeV. We also expose in this region a linear relationship between the trilinear couplings of the stau and the top squark, with both of them being strongly negative as enforced by the Higgs mass and the relic density, which outside of the stau coannihilation region show some tension. The second and the third case, on the other hand, while allowed are disfavored by the constraints from direct detection of dark matter and from $\mathrm{BR}({\mathrm{B}}_{\mathrm{s}}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}})$. Without the anomalous magnetic moment of the muon the fit improves considerably, especially for negative effective $\ensuremath{\mu}$ parameter. We discuss how the considered scenarios could be tested further at the LHC and in dark matter searches.