120497934
Measurement of the cross section for open-beauty production in photon–photon collisions at LEP
Abstract The cross section for open-beauty production in photon–photon collisions is measured using the whole high-energy and high-luminosity data sample collected by the L3 detector at LEP. This corresponds to 627 pb −1 of integrated luminosity for electron–positron centre-of-mass energies from 189 to 209 GeV. Events containing b quarks are identified through their semi-leptonic decay into electrons or muons. The e + e − → e + e − b b ¯ X cross section is measured within our fiducial volume and then extrapolated to the full phase space. These results are found to be in significant excess with respect to Monte Carlo predictions and next-to-leading order QCD calculations.
123184203
Search for scalar leptons and scalar quarks at LEP
Abstract Scalar partners of quarks and leptons, predicted in supersymmetric models, are searched for in e + e − collisions at centre-of-mass energies between 192 and 209 GeV at LEP. No evidence for any such particle is found in a data sample of 450 pb −1 . Upper limits on their production cross sections are set and lower limits on their masses are derived in the framework of the Minimal Supersymmetric Standard Model.
126182293
Evidence of psi(3770) nonD anti-D decay to J / psi pi+ pi-
209856078
Measurement of the Matrix Element for the Decay $\eta^{\prime} \to \eta \pi^+\pi^-$
118744730
Partial wave analysis of ψ(2S) → $p\overline{p}η$
Using a sample of 1.06 x 10(8) psi(2) events collected with the BESIII detector at BEPCII, the decay psi(2S) -> p (p) over bar eta is studied. A partial wave analysis determines that the intermediate state N(1535) with a mass of 1524 +/- 5(-4)(+10) MeV/c(2) and a width of 130(-24-10)(+27+57) MeV/c(2) is dominant in the decay; the product branching fraction is determined to be B(psi(2S) -> N(1535)(p) over bar x B(N(1535) -> p eta + c.c. = 5.2 +/- 0.3(-1.2)(+3.2)) x 10(-5). Furthermore, the branching fraction of psi(2S) -> p (p) over bar eta is measured to be (6.4 +/- 0.2 +/- 0.6) x 10(-5). Here, the first error is statistical and the second is systematic.
188198310
Preliminary design of BES-III trigger system
118514316
Soft theorems in maximally supersymmetric theories
In this paper we study the supersymmetric generalization of the new soft theorem which was proposed by Cachazo and Strominger recently. At tree level, we prove the validity of the super soft theorems in both $$\mathcal{N}=4$$N=4 super-Yang-Mills theory and $$\mathcal{N}=8$$N=8 supergravity using super-BCFW recursion relations. We verify these theorems exactly by showing some examples.
119108034
An explanation of the CDF dijet anomaly within a U(1)X Stueckelberg extension
Abstract We discuss the recent excess seen by the CDF Collaboration in the dijet invariant mass distribution produced in association with a W boson. We analyze the possibility of such a signal within the context of a U ( 1 ) X Stueckelberg extension of the Standard Model where the new gauge boson couples only to quarks. In addition to the analysis of the Wjj anomaly we also discuss the production of Zjj and γjj at the Tevatron. The analysis is then extended to the Large Hadron Collider with s = 7 TeV and predictions for the dijet signals are made.
119254848
Low Mass Neutralino Dark Matter in the MSSM with Constraints from $B_s\to \mu^+\mu^-$ and Higgs Search Limits
An analysis of spin independent neutralino-proton cross sections ${\ensuremath{\sigma}}_{\mathrm{SI}}(\ensuremath{\chi}p)$ that includes this low mass region is given. The analysis is done in minimal supersymmetric standard model (MSSM) with radiative electroweak symmetry breaking (REWSB). It is found that cross sections as large as ${10}^{\ensuremath{-}40}\text{ }\text{ }{\mathrm{cm}}^{2}$ can be accommodated in MSSM within the REWSB framework. However, inclusion of sparticle mass limits from current experiments, as well as lower limits on the Higgs searches from the Tevatron, and the current experimental upper limit on ${B}_{s}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ significantly limit the allowed parameter space reducing ${\ensuremath{\sigma}}_{\mathrm{SI}}(\ensuremath{\chi}p)$ to lie below $\ensuremath{\sim}{10}^{\ensuremath{-}41}\text{ }\text{ }{\mathrm{cm}}^{2}$ or even lower for neutralino masses around 10 GeV. These cross sections are an order of magnitude lower than the cross sections needed to explain the reported data in the recent dark matter experiments in the low neutralino mass region.
56571261
Rotation of surviving companion stars after type Ia supernova explosions in the WD+MS scenario
Context. In the single-degenerate (SD) scenario of type Ia supernovae (SNe Ia) the non-degenerate companion star survives the supernova (SN) explosion and thus should be visible near the center of the SN remnant and may show some unusual features. Therefore, a promising approach to test progenitor models of SNe Ia is to search for the companion star in historical SN remnants. Aims. Here we present the results of three-dimensional (3D) hydrodynamics simulations of the interaction between the SN Ia blast wave and a main-sequence companion taking into consideration its orbital motion and spin. The primary goal of this work is to investigate the rotation of surviving companion stars after SN Ia explosions in the WD+MS scenario. Methods. We used Eggleton's stellar evolution code including the optically thick accretion wind model to obtain realistic models of companion stars. The impact of the supernova blast wave on these companion stars was followed in 3D hydrodynamic simulations employing the smoothed particle hydrodynamics (SPH) code GADGET3. Results. We find that the rotation of the companion star does not significantly affect the amount of stripped mass and the kick velocity caused by the SN impact. However, in our simulations, the rotational velocity of the companion star is significantly reduced to about 14% to 32% of its pre-explosion value due to the expansion of the companion and because 55%-89% of the initial angular momentum is carried away by the stripped matter. Conclusions. Compared with the observed rotational velocity of the presumed companion star of Tycho's supernova, Tycho G, of similar to 6 km s(-1), the final rotational velocity we obtain in our simulations is still higher by at least a factor of two. Whether this difference is significant and may cast doubts on the suggestion that Tycho G is the companion of SN 1572 has to be investigated in future studies. Based on binary population synthesis results, we present for the first time the expected distribution of rotational velocities of companion stars after the SN explosion, which may provide useful information for the identification of the surviving companion in observational searches in other historical SN remnants.
54185957
Colored resonant signals at the LHC: largest rate and simplest topology
We study the colored resonance production at the LHC in a most general approach. We classify the possible colored resonances based on group theory decomposition, and construct their effective interactions with light partons. The production cross section from annihilation of valence quarks or gluons may be on the order of 400–1000 pb at LHC energies for a mass of 1 TeV with nominal couplings, leading to the largest production rates for new physics at the TeV scale, and simplest event topology with dijet final states. We apply the new dijet data from the LHC experiments to put bounds on various possible colored resonant states. The current bounds range from 0.9 to 2.7 TeV. The formulation is readily applicable for future searches including other decay modes.