119256129
AMS-02 and Next-to-Minimal Universal Extra Dimensions
Abstract The anomaly detected by AMS-02 and PAMELA in the cosmic-ray positron flux when interpreted as arising from dark matter annihilation suggests that dark matter may interact differently with hadrons and leptons so as to remain compatible with cosmic-ray antiproton data. Such a scenario is readily accommodated in models with extra spatial dimensions. We study indirect detection of Kaluza–Klein (KK) dark matter in universal extra dimensions with brane-localized terms and fermion bulk masses: next-to-minimal universal extra dimensions. So that an excess of antiprotons is not produced in explaining the positron anomaly, it is necessary that the KK bulk masses in the lepton and hadron sectors be distinct. Even so, we find that cosmic-ray data disfavor a heavy KK photon dark matter scenario. Also, we find these scenarios with flavor-universal bulk masses to be in conflict with dijet and dilepton searches at the LHC.
119306941
Light Higgs Boson, Light Dark Matter and Gamma Rays
A light Higgs boson is preferred by MW and mt measurements. A complex scalar singlet addition to the Standard Model allows a better fit to these measurements through a new light singlet dominated state. It then predicts a light Dark Matter (DM) particle that can explain the signals of DM scattering from nuclei in the CoGeNT and DAMA/LIBRA experiments. Annihilations of this DM in the galactic halo, AA → b ¯¯ c,� + � − , lead to gamma rays that naturally improve a fit to the Fermi Large Area Telescope data in the central galactic regions. The associated light neutral Higgs boson may also be discovered at the Large Hadron Collider.
55754996
On the spin and parity of a single-produced resonance at the LHC
The experimental determination of the properties of the newly discovered boson at the Large Hadron Collider is currently the most crucial task in high energy physics. We show how information about the spin, parity, and, more generally, the tensor structure of the boson couplings can be obtained by studying angular and mass distributions of events in which the resonance decays to pairs of gauge bosons, $ZZ, WW$, and $\gamma \gamma$. A complete Monte Carlo simulation of the process $pp \to X \to VV \to 4f$ is performed and verified by comparing it to an analytic calculation of the decay amplitudes $X \to VV \to 4f$. Our studies account for all spin correlations and include general couplings of a spin $J=0,1,2$ resonance to Standard Model particles. We also discuss how to use angular and mass distributions of the resonance decay products for optimal background rejection. It is shown that by the end of the 8 TeV run of the LHC, it might be possible to separate extreme hypotheses of the spin and parity of the new boson with a confidence level of 99% or better for a wide range of models. We briefly discuss the feasibility of testing scenarios where the more » resonances is not a parity eigenstate. « less
7108596
Current Helicity of Active Regions as a Tracer of Large-scale Solar Magnetic Helicity
We demonstrate that the current helicity observed in solar active regions traces the magnetic helicity of the large-scale dynamo generated field. We use an advanced two-dimensional mean-field dynamo model with dynamo saturation based on the evolution of the magnetic helicity and algebraic quenching. For comparison, we also studied a more basic two-dimensional mean-field dynamo model with simple algebraic alpha-quenching only. Using these numerical models we obtained butterfly diagrams both for the small-scale current helicity and also for the large-scale magnetic helicity, and compared them with the butterfly diagram for the current helicity in active regions obtained from observations. This comparison shows that the current helicity of active regions, as estimated by −A · B evaluated at the depth from which the active region arises, resembles the observational data much better than the small-scale current helicity calculated directly from the helicity evolution equation. Here B and A are, respectively, the dynamo generated mean magnetic field and its vector potential. A theoretical interpretation of these results is given.
199682890
On the spin and parity of a single-produced resonance at the LHC
The experimental determination of the properties of the newly discovered boson at the Large Hadron Collider is currently the most crucial task in high energy physics. We show how information about the spin, parity, and, more generally, the tensor structure of the boson couplings can be obtained by studying angular and mass distributions of events in which the resonance decays to pairs of gauge bosons, ZZ,WW, and . A complete Monte Carlo simulation of the process pp → X → V V → 4f is performed and verified by comparing it to an analytic calculation of the decay amplitudes X → V V → 4f. Our studies account for all spin correlations and include general couplings of a spin J = 0,1,2 resonance to Standard Model particles. We also discuss how to use angular and mass distributions of the resonance decay products for optimal background rejection. It is shown that by the end of the 8 TeV run of the LHC, it might be possible to separate extreme hypotheses of the spin and parity of the new boson with a confidence level of 99% or better for a wide range of models. We briefly discuss the feasibility of testing scenarios where the resonances is not a parity eigenstate.
116437774
Study of rare gluonic penguin decays B to phi K pi (pi) at BABAR
The Standard Model of particle physics describes the elementary particles and interactions at an energy level around 100 GeV or less with unprecedented success. However, it is far from being conclusive, with some essential pieces not exactly understood. While the direct access to new physics beyond the Standard Model may be beyond the energy reach of the current operating accelerators, one can look for them in virtual transitions, such as the rare gluonic penguin decays B → φKπ(π). Furthermore, in the B → φ(1020)K(892) decay an interesting polarization puzzle which could indicate some new physics effects has been observed and thereby motivates this thesis. Three amplitude and angular analyses on decays B → φK (∗) J are performed based on about 465 million or 384 millionBB pairs recorded with the BABAR detector. Twelve K (∗) J resonances are included in four different final states Kπ, K Sπ , Kπ and Kππ. Branching fractions, CP -violation parameters and polarizations measurements are made. The branching fractions of vector–scalar decays B → φ(Kπ) 0 and B → φ(Kπ) 0 are measured to be (4.3±0.6±0.4)×10−6 and (7.0±1.3±0.9)×10−6, respectively. The
96264452
Rare Hadronic B Decays to Vector, Axial-Vector and Tensors
We review the recent BaBar measurements of several rare B decays, including vector–axial-vector decays B ± → φ K 1 ( 1270 ) ± , B ± → φ K 1 ( 1400 ) ± and B ± → b 1 ∓ ρ ± , vector-vector decays B ± → φ K ∗ ( 1410 ) ± , B 0 → K ∗ 0 K ¯ ∗ 0 , B 0 → K ∗ 0 K ∗ 0 and B 0 → K ∗ + K ∗ − , vector-tensor decays B ± → φ K 2 ∗ ( 1430 ) ± and φ K 2 ( 1770 ) / ( 1820 ) ± , and vector-scalar decays B ± → φ K 0 ∗ ( 1430 ) ± . Understanding the observed polarization pattern requires amplitude contributions from an uncertain source.