Performance of RF MEMS switches at low temperatures

The actuation voltage of microelectromechanical system (MEMS) \ud metal switches was investigated at temperatures ranging from 10 to 290 K. The investigation shows a 50% increase in the actuation voltage at low temperature. A comparison has been made using a published model and showed similar increment of actuation voltage at low temperature

Lepton Flavor Violation in Z and Lepton Decays in Supersymmetric Models

The observation of charged lepton flavor non-conservation would be a clear signature of physics beyond the Standard Model. In particular, supersymmetric (SUSY) models introduce mixings in the sneutrino and the charged slepton sectors which could imply flavor-changing processes at rates accessible to upcoming experiments. In this paper we analyze the possibility to observe Z --> lep_I lep_J in the GigaZ option of TESLA at DESY. We show that although models with SUSY masses above the current limits could predict a branching ratio BR(Z --> mu e) accessible to the experiment, they would imply an unobserved rate of mu --> e gamma and thus are excluded. In models with a small mixing angle between the first and the third (or the second and the third) slepton families GigaZ could observe Z --> tau mu (or Z --> tau e) consistently with present bounds on lep_J --> lep_I gamma. In contrast, if the mixing angles between the three slepton families are large the bounds from mu --> e gamma push these processes below the reach of GigaZ. We show that in this case the masses of the three slepton families must be strongly degenerated (with mass differences of order 10^{-3}). We update the limits on the slepton mass insertions delta_{LL,RR,LR} and discuss the correlation between flavor changing and g_mu-2 in SUSY models.Comment: 23 pages, 6 figures. Version to appear in Phys. Rev.

CP violation in Bd,s→l+l−B_{d,s} \to l^+l^- in the model III 2HDM

We have calculated the Wilson coefficients $C_{10}, C_{Q_i}$ (i=1,2) in the $\bar{MS}$ renormalization scheme in the model III 2HDM. Using the obtained Wilson coefficients, we have analyzed the CP violation in decays $B^0_q\to l^+l^-$ (q=d,s) in the model. The CP asymmetry, $A_{CP}$, depends on the parameters of models and $A_{CP}$ in $B_d\to l^+l^-$ can be as large as 40% and 35% for $l=\tau$ and $l=\mu$ respectively. It can reach 4% for $B^0_s$ decays. Because in SM CP violation is smaller than or equal to O($10^{-3}$) which is unobservably small, an observation of CP asymmetry in the decays $B^0_q \to l^+l^- (q=d,s)$ would unambiguously signal the existence of new physics.Comment: revtex4, 16 pages, 7 figure

Kaluza-Klein gravitino production with a single photon at e^+ e^- colliders

In a supersymmetric large extra dimension scenario, the production of Kaluza-Klein gravitinos accompanied by a photino at e^+ e^- colliders is studied. We assume that a bulk supersymmetry is softly broken on our brane such that the low-energy theory resembles the MSSM. Low energy supersymmetry breaking is further assumed as in GMSB, leading to sub-eV mass shift in each KK mode of the gravitino from the corresponding graviton KK mode. Since the photino decays within a detector due to its sufficiently large inclusive decay rate into a photon and a gravitino, the process e^+ e^- -> photino + gravitino yields single photon events with missing energy. Even if the total cross section can be substantial at sqrt(s)=500 GeV, the KK graviton background of e^+ e^- -> photon + graviton is kinematically advantageous and thus much larger. It is shown that the observable, sigma(e^-_L)-sigma(e^-_R), can completely eliminate the KK graviton background but retain most of the KK gravitino signal, which provides a unique and robust method to probe the supersymmetric bulk.Comment: Reference added and typos correcte

Muon anomalous magnetic moment, lepton flavor violation, and flavor changing neutral current processes in SUSY GUT with right-handed neutrino

Motivated by the large mixing angle solutions for the atmospheric and solar neutrino anomalies, flavor changing neutral current processes and lepton flavor violating processes as well as the muon anomalous magnetic moment are analyzed in the framework of SU(5) SUSY GUT with right-handed neutrino. In order to explain realistic mass relations for quarks and leptons, we take into account effects of higher dimensional operators above the GUT scale. It is shown that the supersymmetric (SUSY) contributions to the CP violation parameter in $K^0-\bar{K}^0$ mixing, $\epsilon_K$, the $\mu \to e \gamma$ branching ratio, and the muon anomalous magnetic moment become large in a wide range of parameter space. We also investigate correlations among these quantities. Within the current experimental bound of $\text{B}(\mu \to e \gamma)$, large SUSY contributions are possible either in the muon anomalous magnetic moment or in $\epsilon_K$. In the former case, the favorable value of the recent muon anomalous magnetic moment measurement at the BNL E821 experiment can be accommodated. In the latter case, the allowed region of the Kobayashi-Maskawa phase can be different from the prediction within the Standard Model (SM) and therefore the measurements of the CP asymmetry of $B\to J/\psi K_S$ mode and $\Delta m_{B_s}$ could discriminate this case from the SM. We also show that the $\tau \to \mu \gamma$ branching ratio can be close to the current experimental upperbound and the mixing induced CP asymmetry of the radiative B decay can be enhanced in the case where the neutrino parameters correspond to the Mikheyev-Smirnov-Wolfenstein small mixing angle solution.Comment: 70 pages, 14 figure

Softening the Supersymmetric Flavor Problem in Orbifold GUTs

The infra-red attractive force of the bulk gauge interactions is applied to soften the supersymmetric flavor problem in the orbifold SU(5) GUT of Kawamura. Then this force aligns in the infra-red regime the soft supersymmetry breaking terms out of their anarchical disorder at a fundamental scale, in such a way that flavor-changing neutral currents as well as dangerous CP-violating phases are suppressed at low energies. It is found that this dynamical alignment is sufficiently good compared with the current experimental bounds, as long as the diagonalization matrices of the Yukawa couplings are CKM-like.Comment: 15 pages,4 figure

Evaluation of cleaning efficiency of ultrafiltration membranes fouled by BSA using FTIR–ATR as a tool

The goal of this paper was to study the cleaning of two polyethersulfone (PES) membranes of different molecular weight and fouled with BSA solution. Ultrafiltration (UF) membranes were tested in a flat sheet module. Fouling experiments were carried out at a transmembrane pressure of 2 bar and cross flow velocity of 2 m/s during 2 h. Cleaning experiments were performed at 1 bar and 2.2 m/s. To compare the efficiency of different cleaning solutions (NaOH and P3-Ultrasil 115), quantification of residual pro-teins on the membrane was carried out by FTIR ATR. To have a better understanding of the cleaning pro-cess, characteristics of the feed solution and of the membranes were considered and contact angle of the membranes before and after the cleaning was measured. Membrane resistances were also calculated at the different stages. Results from resistances showed that reversible fouling prevail over irreversible fouling for both membranes. P3-Ultrasil 115 was a better cleaning agent than NaOH solution since cleaning efficiencies (CE) of 100% for both membranes were achieved for P3-Ultrasil 115 solution. Residual pro-teins on the membrane after the cleaning were measured both by FTIR ATR and Pierce-BCA method. Results showed that 100% of permeability recovery did not imply the complete BSA removal from the membrane. However, these measurements corroborated that P3-Ultrasil 115 had removed a higher amount of proteins than NaOH solution.This work was supported by the Spanish Ministry of Science and Innovation (CTM 2010-20.186).Luján Facundo, MJ.; Mendoza Roca, JA.; Cuartas Uribe, BE.; Alvarez Blanco, S. (2015). Evaluation of cleaning efficiency of ultrafiltration membranes fouled by BSA using FTIR–ATR as a tool. Journal of Food Engineering. 163:1-8. https://doi.org/10.1016/j.jfoodeng.2015.04.015S1816

Heavy quarkonium: progress, puzzles, and opportunities

A golden age for heavy quarkonium physics dawned a decade ago, initiated by the confluence of exciting advances in quantum chromodynamics (QCD) and an explosion of related experimental activity. The early years of this period were chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in 2004, which presented a comprehensive review of the status of the field at that time and provided specific recommendations for further progress. However, the broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles could only be partially anticipated. Since the release of the YR, the BESII program concluded only to give birth to BESIII; the $B$-factories and CLEO-c flourished; quarkonium production and polarization measurements at HERA and the Tevatron matured; and heavy-ion collisions at RHIC have opened a window on the deconfinement regime. All these experiments leave legacies of quality, precision, and unsolved mysteries for quarkonium physics, and therefore beg for continuing investigations. The plethora of newly-found quarkonium-like states unleashed a flood of theoretical investigations into new forms of matter such as quark-gluon hybrids, mesonic molecules, and tetraquarks. Measurements of the spectroscopy, decays, production, and in-medium behavior of c\bar{c}, b\bar{b}, and b\bar{c} bound states have been shown to validate some theoretical approaches to QCD and highlight lack of quantitative success for others. The intriguing details of quarkonium suppression in heavy-ion collisions that have emerged from RHIC have elevated the importance of separating hot- and cold-nuclear-matter effects in quark-gluon plasma studies. This review systematically addresses all these matters and concludes by prioritizing directions for ongoing and future efforts.Comment: 182 pages, 112 figures. Editors: N. Brambilla, S. Eidelman, B. K. Heltsley, R. Vogt. Section Coordinators: G. T. Bodwin, E. Eichten, A. D. Frawley, A. B. Meyer, R. E. Mitchell, V. Papadimitriou, P. Petreczky, A. A. Petrov, P. Robbe, A. Vair

Branching fraction and CP asymmetry of the decays B+→K0Sπ+ and B+→K0SK+

An analysis of B+ → K0 Sπ+ and B+ → K0 S K+ decays is performed with the LHCb experiment. The pp collision data used correspond to integrated luminosities of 1 fb−1 and 2 fb−1 collected at centre-ofmass energies of √ s = 7 TeV and √ s = 8 TeV, respectively. The ratio of branching fractions and the direct CP asymmetries are measured to be B(B+ → K0 S K+ )/B(B+ → K0 Sπ+ ) = 0.064 ± 0.009 (stat.) ± 0.004 (syst.), ACP(B+ → K0 Sπ+ ) = −0.022 ± 0.025 (stat.) ± 0.010 (syst.) and ACP(B+ → K0 S K+ ) = −0.21 ± 0.14 (stat.) ± 0.01 (syst.). The data sample taken at √ s = 7 TeV is used to search for B+ c → K0 S K+ decays and results in the upper limit ( fc · B(B+ c → K0 S K+ ))/( fu · B(B+ → K0 Sπ+ )) < 5.8 × 10−2 at 90% confidence level, where fc and fu denote the hadronisation fractions of a ¯b quark into a B+ c or a B+ meson, respectively

Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}}=2.76 TeV

The elliptic, $v_2$, triangular, $v_3$, and quadrangular, $v_4$, azimuthal anisotropic flow coefficients are measured for unidentified charged particles, pions and (anti-)protons in Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV with the ALICE detector at the Large Hadron Collider. Results obtained with the event plane and four-particle cumulant methods are reported for the pseudo-rapidity range $|\eta|<0.8$ at different collision centralities and as a function of transverse momentum, $p_{\rm T}$, out to $p_{\rm T}=20$ GeV/$c$. The observed non-zero elliptic and triangular flow depends only weakly on transverse momentum for $p_{\rm T}>8$ GeV/$c$. The small $p_{\rm T}$ dependence of the difference between elliptic flow results obtained from the event plane and four-particle cumulant methods suggests a common origin of flow fluctuations up to $p_{\rm T}=8$ GeV/$c$. The magnitude of the (anti-)proton elliptic and triangular flow is larger than that of pions out to at least $p_{\rm T}=8$ GeV/$c$ indicating that the particle type dependence persists out to high $p_{\rm T}$.Comment: 16 pages, 5 captioned figures, authors from page 11, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/186