Decaying Hidden Gauge Boson and the PAMELA and ATIC/PPB-BETS Anomalies

We show that the PAMELA anomaly in the positron fraction as well as the ATIC/PPB-BETS excesses in the e^- + e^+ flux are simultaneously explained in our scenario that a hidden U(1)H gauge boson constitutes dark matter of the Universe and decays into the standard-model particles through a kinetic mixing with an U(1)B-L gauge boson. Interestingly, the B-L charge assignment suppresses an antiproton flux in consistent with the PAMELA and BESS experiments, while the hierarchy between the B-L symmetry breaking scale and the weak scale naturally leads to the right lifetime of O(10^26) seconds.Comment: the version accepted by Progress of Theoretical Physics (PTP

Probing Variant Axion Models at LHC

We study collider implications of variant axion models which naturally avoid the cosmological domain wall problem. We find that in such models the branching ratio of $h \to \gamma\gamma$ can be enhanced by a factor of 5 up to 30 as compared with the standard model prediction. The $h \to \gamma\gamma$ process is therefore a promising channel to discover a light Higgs boson at the LHC and to probe the Peccei-Quinn charge assignment of the standard model fields from Yukawa interactions.Comment: 16 pages, 4 figure

Direct grafting of tetraaniline via perfluorophenylazide photochemistry to create antifouling, low bio-adhesion surfaces.

Conjugated polyaniline has shown anticorrosive, hydrophilic, antibacterial, pH-responsive, and pseudocapacitive properties making it of interest in many fields. However, in situ grafting of polyaniline without harsh chemical treatments is challenging. In this study, we report a simple, fast, and non-destructive surface modification method for grafting tetraaniline (TANI), the smallest conjugated repeat unit of polyaniline, onto several materials via perfluorophenylazide photochemistry. The new materials are characterized by nuclear magnetic resonance (NMR) and electrospray ionization (ESI) mass spectroscopy. TANI is shown to be covalently bonded to important carbon materials including graphite, carbon nanotubes (CNTs), and reduced graphene oxide (rGO), as confirmed by transmission electron microscopy (TEM). Furthermore, large area modifications on polyethylene terephthalate (PET) films through dip-coating or spray-coating demonstrate the potential applicability in biomedical applications where high transparency, patternability, and low bio-adhesion are needed. Another important application is preventing biofouling in membranes for water purification. Here we report the first oligoaniline grafted water filtration membranes by modifying commercially available polyethersulfone (PES) ultrafiltration (UF) membranes. The modified membranes are hydrophilic as demonstrated by captive bubble experiments and exhibit extraordinarily low bovine serum albumin (BSA) and Escherichia coli adhesions. Superior membrane performance in terms of flux, BSA rejection and flux recovery after biofouling are demonstrated using a cross-flow system and dead-end cells, showing excellent fouling resistance produced by the in situ modification

Precise Measurement of Gravity Variations During a Total Solar Eclipse

The variations of gravity were measured with a high precision LaCoste-Romberg D gravimeter during a total solar eclipse to investigate the effect of solar eclipse on the gravitational field. The observed anomaly $(7.0 \pm 2.7) \times 10^{-8}$ m/s$^2$ during the eclipse implies that there may be a shielding property of gravitation

Decaying Hidden Gauge Boson and the PAMELA and ATIC/PPB-BETS Anomalies

Abstract We show that the PAMELA anomaly in the positron fraction as well as the ATIC/PPB-BETS excesses in the e − + e + flux are simultaneously explained in our scenario that a hidden U (1) H gauge boson constitutes dark matter of the Universe and decays into the standard-model particles 1 The nature of dark matter has been a big mystery in modern cosmology. Recently, there appeared several exciting observational data on high-energy cosmic-ray particles, which may be shedding light on this issue. The PAMELA data We have recently proposed a scenario that a hidden U(1) H gauge boson constitutes dark matter of the Universe and decays into the standard-model (SM) particles through a kinetic mixing with a U(1) B−L gauge boson #1 In this letter we show that our model can naturally explain both the PAMELA and ATIC/PPB-BETS anomalies, for the hidden gauge boson of a mass about 1.2 TeV, while the antiproton flux is still suppressed enough due to the B − L charge assignment. Interestingly, our scenario predicts an excess in the diffuse gamma-ray background peaked around 100 GeV, which will be tested soon by the Fermi (formerly GLAST) [9] satellite in operation. Let us here briefly review our set-up (see Ref. [5] for more details). We introduce an extra dimension with two branes at the boundaries. Suppose that the hidden gauge sector is on one brane and the SM particles are on the other brane, which are well separated from each other so that direct interactions between the two sectors are exponentially suppressed. where λ is a coefficient of the kinetic mixing, q i denotes the B − L charge of the fermion ψ i , and m and M are the masses of the hidden gauge boson A H and the U(1) B−L gauge boson, respectively. The partial decay width for the SM fermion pair is where we have neglected the fermion mass, and N i is the color factor (3 for quarks and 1 for leptons). Note that the coefficient N i q 2 i is 1/3 and 1 for quarks and leptons, respectively, which results in the suppression of the antiproton flux. The lifetime τ is therefore given by where the sum is taken over the SM fermions. It should be noted that the branching ratios are not sensitive to the mass of A H and they simply reflect the B − L charge assignment, which makes our analysis very predictive. Let us now estimate the spectra for the positron fraction, (e − + e + ), gamma-ray and antiproton fluxes based on the decay modes discussed above. The branching ratios are 2/39 and 2/13 for a quark pair and a charged lepton pair, respectively. To estimate the spectra of the gamma, positrons and antiprotons, we use the PYTHIA [11] Monte Carlo program

Laser acceleration of protons using multi-ion plasma gaseous targets

We present a theoretical and numerical study of the novel acceleration scheme by applying a combination of laser radiation pressure and shielded Coulomb repulsion in laser acceleration of protons in multi-species gaseous targets. By using a circularly polarized CO2 laser pulse with a wavelength of 10 μm, much greater than that of a Ti:Sapphire laser, the critical density is significantly reduced, and a high-pressure gaseous target can be used to achieve an overdense plasma. This gives us a larger degree of freedom in selecting the target compounds or mixtures, as well as their density and thickness profiles. By impinging such a laser beam on a carbon-hydrogen target, the gaseous target is first compressed and accelerated by radiation pressure until the electron layer disrupts, after which the protons are further accelerated by the electron-shielded carbon ion layer. An 80 MeV quasi-monoenergetic proton beam can be generated using a half-sine shaped laser beam with peak power 70 TW and pulse duration of 150 wave periods

Quenched Charmed Meson Spectra using Tadpole Improved Quark Action on Anisotropic Lattices

Charmed meson charmonium spectra are studied with improved quark actions on anisotropic lattices. We measured the pseudo-scalar and vector meson dispersion relations for 4 lowest lattice momentum modes with quark mass values ranging from the strange quark to charm quark with 3 different values of gauge coupling $\beta$ and 4 different values of bare speed of light $\nu$. With the bare speed of light parameter $\nu$ tuned in a mass-dependent way, we study the mass spectra of $D$, $D_s$, $\eta_c$, $D^{\ast}$, $D_s^{\ast}$ and $J/\psi$ mesons. The results extrapolated to the continuum limit are compared with the experiment and qualitative agreement is found.Comment: 8 pages, 2 figures, latex fil

Cosmic rays from Leptonic Dark Matter

If dark matter possesses a lepton number, it is natural to expect the dark-matter annihilation and/or decay mainly produces the standard model leptons, while negligible amount of the antiproton is produced. To illustrate such a simple idea, we consider a scenario that a right-handed sneutrino dark matter decays into the standard model particles through tiny R-parity violating interactions. Interestingly enough, charged leptons as well as neutrinos are directly produced, and they can lead to a sharp peak in the predicted positron fraction. Moreover, the decay of the right-handed sneutrino also generates diffuse continuum gamma rays which may account for the excess observed by EGRET, while the primary antiproton flux can be suppressed. Those predictions on the cosmic-ray fluxes of the positrons, gamma rays and antiprotons will be tested by the PAMELA and FGST observatories.Comment: 21 pages, 4 figures, 2 tables, updated plots including PAMELA dat

Perturbative QCD analysis of B→ϕK∗B \to \phi K^* decays

We study the first observed charmless $B\to VV$ modes, the $B\to\phi K^*$ decays, in perturbative QCD formalism. The obtained branching ratios $B(B\to\phi K^*)\sim 15 \times 10^{-6}$ are larger than $\sim 9\times 10^{-6}$ from QCD factorization. The comparison of the predicted magnitudes and phases of the different helicity amplitudes, and branching ratios with experimental data can test the power counting rules, the evaluation of annihilation contributions, and the mechanism of dynamical penguin enhancement in perturbative QCD, respectively.Comment: 14 pages, 2 tables, brief disscussion on hard sacle added, version to appear in PR