This communication reports a new theranostic system with a combination of capabilities to both enhance the contrast of photoacoustic (PA) imaging and control the release of a chemical or biological effecter by high-intensity focused ultrasound (HIFU). The fabrication of this system simply involves filling the hollow interiors of gold nanocages with a phase-change material (PCM) such as 1-tetradecanol that has a melting point of 38–39 °C. The PCM can be pre-mixed and thus loaded with a dye, as well as other chemical or biological effecters. When exposed to direct heating or HIFU, the PCM will melt and escape from the interiors of nanocages through small pores on the surface, concurrently releasing the encapsulated molecules into the surrounding medium. We can control the release profile by varying the power of HIFU, the duration of exposure to HIFU, or both.

This paper presents a search for the pair production of top squarks in events with a single isolated electron or muon, jets, large missing transverse momentum, and large transverse mass. The data sample corresponds to an integrated luminosity of 19.5 fb −1 of pp collisions collected in 2012 by the CMS experiment at the LHC at a center-of-mass energy of √ s = 8 TeV. No significant excess in data is observed above the expectation from standard model processes. The results are interpreted in the context of supersymmetric models with pair production of top squarks that decay either to a top quark and a neutralino or to a bottom quark and a chargino. For small mass values of the lightest supersymmetric particle, top-squark mass values up to around 650 GeV are excluded.Published in the European Physical Journal C as doi:10.1140/epjc/s10052-013-2677-2. IntroductionThe standard model (SM) has been extremely successful at describing particle physics phenomena. However, it suffers from such shortcomings as the hierarchy problem, where fine-tuned cancellations of large quantum corrections are required in order for the Higgs boson to have a mass at the electroweak symmetry breaking scale of order 100 GeV [1][2][3][4][5][6]. Supersymmetry (SUSY) is a popular extension of the SM that postulates the existence of a superpartner for every SM particle, with the same quantum numbers but differing by one half-unit of spin. SUSY potentially provides a "natural", i.e., not fine-tuned, solution to the hierarchy problem through the cancellations of the quadratic divergences of the top-quark and top-squark loops. In addition, it provides a connection to cosmology, with the lightest supersymmetric particle (LSP), if neutral and stable, serving as a dark matter candidate in R-parity conserving SUSY models. This paper describes a search for the pair production of top squarks using the full dataset collected at √ s = 8 TeV by the Compact Muon Solenoid (CMS) experiment [7] at the Large Hadron Collider (LHC) during 2012, corresponding to an integrated luminosity of 19.5 fb −1 . This search is motivated by the consideration that relatively light top squarks, with masses below around 1 TeV, are necessary if SUSY is to be the natural solution to the hierarchy problem [8][9][10][11][12]. These constraints are especially relevant given the recent discovery of a particle that closely resembles a Higgs boson, with a mass of ∼125 GeV [13][14][15]. Searches for top-squark pair production have also been performed by the ATLAS Collaboration at the LHC in several final states [16][17][18][19][20], and by the CDF [21] and D0 [22] Collaborations at the Tevatron.The search presented here focuses on two decay modes of the top squark ( t): t → t χ 0 1 and t → b χ + . These modes are expected to have large branching fractions if kinematically allowed. Here t and b are the top and bottom quarks, and the neutralinos ( χ 0 ) and charginos ( χ ± ) are the mass eigenstates formed by the linear combination of the gauginos and higgsinos, which are the fermi...

Searches for resonances decaying into pairs of jets are performed using proton-proton collision data collected at √ s = 13 TeV corresponding to an integrated luminosity of up to 36 fb −1 . A low-mass search, for resonances with masses between 0.6 and 1.6 TeV, is performed based on events with dijets reconstructed at the trigger level from calorimeter information. A high-mass search, for resonances with masses above 1.6 TeV, is performed using dijets reconstructed offline with a particle-flow algorithm. The dijet mass spectrum is well described by a smooth parameterization and no evidence for the production of new particles is observed. Upper limits at 95% confidence level are reported on the production cross section for narrow resonances with masses above 0.6 TeV. In the context of specific models, the limits exclude string resonances with masses below 7.7 TeV, scalar diquarks below 7.2 TeV, axigluons and colorons below 6.1 TeV, excited quarks below 6.0 TeV, color-octet scalars below 3.4 TeV, W bosons below 3.3 TeV, Z bosons below 2.7 TeV, Randall-Sundrum gravitons below 1.8 TeV and in the range 1.9 to 2.5 TeV, and dark matter mediators below 2.6 TeV. The limits on both vector and axial-vector mediators, in a simplified model of interactions between quarks and dark matter particles, are presented as functions of dark matter particle mass and coupling to quarks. Searches are also presented for broad resonances, including for the first time spin-1 resonances with intrinsic widths as large as 30% of the resonance mass. The broad resonance search improves and extends the exclusions of a dark matter mediator to larger values of its mass and coupling to quarks. IntroductionModels of physics that extend the standard model (SM) often require new particles that couple to quarks (q) and/or gluons (g) and decay to dijets. The natural width of resonances in the dijet mass (m jj ) spectrum increases with the coupling, and may vary from narrow to broad compared to the experimental resolution. For example, in a model in which dark matter (DM) particles couple to quarks through a DM mediator, the mediator can decay to either a pair of DM particles or a pair of jets and therefore can be observed as a dijet resonance [1, 2] that is either narrow or broad, depending on the strength of the coupling. When the resonance is broad, its observed line-shape depends significantly on the resonance spin. Here we report a search for narrow dijet resonances and a complementary search for broad resonances that considers multiple values of the resonance spin and widths as large as 30% of the resonance mass. Both approaches are sensitive to resonances with intrinsic widths that are small compared to the experimental resolution, but the broad resonance search is also sensitive to resonances with larger intrinsic widths. We explore the implications for multiple specific models of dijet resonances and for a range of quark coupling strength for a DM mediator.We present model independent results for s-channel dijet resonances and apply the results to...

We present a measurement of forward-backward asymmetry in top quark-antiquark production in proton-antiproton collisions in the final state containing a lepton and at least four jets. Using a dataset corresponding to an integrated luminosity of 5.4 fb −1 , collected by the D0 experiment at the Fermilab Tevatron Collider, we measure the tt forward-backward asymmetry to be (9.2 ± 3.7)% at the reconstruction level. When corrected for detector acceptance and resolution, the asymmetry is found to be (19.6 ± 6.5)%. We also measure a corrected asymmetry based on the lepton from a top quark decay, found to be (15.2 ± 4.0)%. The results are compared to predictions based on the next-to-leading-order QCD generator mc@nlo. The sensitivity of the measured and predicted asymmetries to the modeling of gluon radiation is discussed.

No abstract