123620386
Magnetic Dipole and Electric Quadrupole Moments of the W+/- Meson
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.
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.
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.
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.
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.
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.
118612935
The impact of propagation uncertainties on the potential Dark Matter contribution to the Fermi LAT mid-latitude gamma-ray data
We investigate the extent to which the uncertainties associated with the propagation of Galactic cosmic rays impact upon estimates for the {gamma}-ray flux from the mid-latitude region. We consider contributions from both standard astrophysical background (SAB) processes as well as resolved point sources. We have found that the uncertainties in the total {gamma}-ray flux from the mid-latitude region relating to propagation parameter values consistent with local B/C and {sup 10}Be/{sup 9}Be data dominate by 1-2 orders of magnitude. These uncertainties are reduced to less than an order of magnitude when the normalizations of the SAB spectral components are fitted to the corresponding Fermi LAT data. We have found that for many propagation parameter configurations (PPCs) our fits improve when an extragalactic background (EGB) component is simultaneously fitted to the data. We also investigate the improvement in our fits when a flux contribution from neutralino dark matter (DM), described by the minimal supersymmetric standard model, was simultaneously fitted to the data. We consider three representative cases of neutralino DM for both Burkert and Einasto DM density profiles, in each case simultaneously fitting a boost factor of the DM contribution together with the SAB and EGB components. We have found that formore » several PPCs there are significant improvements in our fits, yielding both substantial EGB and DM components, where for a few of these PPCs the best-fit EGB component is consistent with recent estimates by the Fermi Collaboration.« less
55446956
Missing energy signatures of dark matter at the LHC
We use ATLAS and CMS searches in the mono-jet + missing energy and mono-photon + missing energy final state to set limits on the couplings of dark matter to quarks and gluons. Working in an effective field theory framework we compare several existing mono-jet analyses and find that searches with high p_T cuts are more sensitive to dark matter. We constrain the suppression scale of the effective dark matter-Standard Model interactions, and convert these limits into bounds on the cross sections relevant to direct and indirect detection. We find that, for certain types of operators, in particular spin-independent dark matter-gluon couplings and spin-dependent dark matter-quark couplings, LHC constraints from the mono-jet channel are competitive with, or superior to, limits from direct searches up to dark matter masses of order 1 TeV. Comparing to indirect searches, we exclude, at 90% C.L., dark matter annihilating to quarks with the annihilation cross section of a thermal relic for masses below ~ 15-70 GeV, depending on the Lorentz structure of the effective couplings. Mono-photon limits are somewhat weaker than mono-jet bounds, but still provide an important cross check in the case of a discovery in mono-jets. We also discuss the possibility that dark matter--Standard Model interactions at LHC energies cannot be described by effective operators, in which case we find that constraints can become either significantly stronger, or considerably weaker, depending on the mass and width of the intermediate particle. We also discuss the special case of dark matter coupling to the Higgs boson, and we show that searches for invisible Higgs decays would provide superior sensitivity, particularly for a light Higgs mass and light dark matter.
59134775
A generic method to constrain the dark matter model parameters from Fermi observations of dwarf spheroids
Observation of gamma-rays from dwarf galaxies is an effective way to search for particle dark matter. Using 4-year data of Fermi-LAT observations on a series of Milky Way satellites, we develop a general way to search for the signals from dark matter annihilation in such objects. Instead of giving prior information about the energy spectrum of dark matter annihilation, we bin the Fermi-LAT data into several energy bins and build a likelihood map in the "energy bin - flux" plane. The final likelihood of any spectrum can be easily derived through combining the likelihood of all the energy bins. It gives consistent result with that directly calculated using the Fermi Scientific Tool. This method is very efficient for the study of any specific dark matter models with gamma-rays. We use the new likelihood map with Fermi-LAT 4 year data to fit the parameter space in three representative dark matter models: i) toy dark matter model, ii) effective dark matter operators, and iii) supersymmetric neutralino dark matter.