Mixed Wino Dark Matter: Consequences for Direct, Indirect and Collider Detection

In supersymmetric models with gravity-mediated SUSY breaking and gaugino mass unification, the predicted relic abundance of neutralinos usually exceeds the strict limits imposed by the WMAP collaboration. One way to obtain the correct relic abundance is to abandon gaugino mass universality and allow a mixed wino-bino lightest SUSY particle (LSP). The enhanced annihilation and scattering cross sections of mixed wino dark matter (MWDM) compared to bino dark matter lead to enhanced rates for direct dark matter detection, as well as for indirect detection at neutrino telescopes and for detection of dark matter annihilation products in the galactic halo. For collider experiments, MWDM leads to a reduced but significant mass gap between the lightest neutralinos so that chi_2^0 two-body decay modes are usually closed. This means that dilepton mass edges-- the starting point for cascade decay reconstruction at the CERN LHC-- should be accessible over almost all of parameter space. Measurement of the m_{\tz_2}-m_{\tz_1} mass gap at LHC plus various sparticle masses and cross sections as a function of beam polarization at the International Linear Collider (ILC) would pinpoint MWDM as the dominant component of dark matter in the universe.Comment: 29 pages including 19 eps figure

Biochemical Oscillations and Cellular Rhythms: The Molecular Bases of Periodic and Chaotic Behavior

the threads of complexity in chemical systems. The promise of this new activity is particularly rich for macromolecules (including biologically relevant macromolecules), in which opportunities for the existence of many different molecular conformations, each with different properties, are high. At the core of chemical interest in complexity are the two fundamental problems concerning life, that is, trying to understand (i) how collections of molecules can give rise to the varieties of behaviors that characterize cells and organisms and (ii) how individual molecules might have originally assembled into collections that had the characteristics of life (energy dissipation, self-replication, and adaptation). Whether the understanding of complexity at the molecular level will reveal important elements of the structure of life is unclear. We do not know if it is conceptually possible to connect molecular-level processes to organismic behavior deterministically. Certainly, knowing everything about the electronic properties of Si and the operating characteristics of transistors tells very little about the higher level characteristics of computers. Fortunately, there is also the inverse opportunity: learning from biological complexity as a method of stimulating new chemistry. With this opportunity, there is great reason for optimism. Biological systems display such a large number of remarkable capabilities (and capabilities that are so clearly complex) that their analysis will unquestionably be a rich source of models for new areas of chemistry. ANNs are one example of a successful transfer of information about a complex biological system to nonbiological applications. ANNs were developed, in part, as a tool with which to model the brain. To what extent current ANNs do so is a continuing subject of discussion, but the effort to make the connection between ANNs and brains (and to learn from the brain) has unquestionably expanded the capabilities of computation. In this same sense, biology (and perhaps also complex materials) offers examples of complex systems that show types of behavior that are now uncommon in molecular chemistry. One of the opportunities in fundamental chemical research is to learn from biology and to use what is learned to design nonbiological systems that dissipate energy, replicate, and adapt. Whether such systems would model life is moot; they would unquestionably be very interesting and probably very important

Study of e+e−→ppˉe^+e^- \rightarrow p\bar{p} in the vicinity of ψ(3770)\psi(3770)

Using 2917 $\rm{pb}^{-1}$ of data accumulated at 3.773~$\rm{GeV}$, 44.5~$\rm{pb}^{-1}$ of data accumulated at 3.65~$\rm{GeV}$ and data accumulated during a $\psi(3770)$ line-shape scan with the BESIII detector, the reaction $e^+e^-\rightarrow p\bar{p}$ is studied considering a possible interference between resonant and continuum amplitudes. The cross section of $e^+e^-\rightarrow\psi(3770)\rightarrow p\bar{p}$, $\sigma(e^+e^-\rightarrow\psi(3770)\rightarrow p\bar{p})$, is found to have two solutions, determined to be ($0.059\pm0.032\pm0.012$) pb with the phase angle $\phi = (255.8\pm37.9\pm4.8)^\circ$ ($<$0.11 pb at the 90% confidence level), or $\sigma(e^+e^-\rightarrow\psi(3770)\rightarrow p\bar{p}) = (2.57\pm0.12\pm0.12$) pb with $\phi = (266.9\pm6.1\pm0.9)^\circ$ both of which agree with a destructive interference. Using the obtained cross section of $\psi(3770)\rightarrow p\bar{p}$, the cross section of $p\bar{p}\rightarrow \psi(3770)$, which is useful information for the future PANDA experiment, is estimated to be either ($9.8\pm5.7$) nb ($<17.2$ nb at 90% C.L.) or $(425.6\pm42.9)$ nb

An embedding technique to determine ττ backgrounds in proton-proton collision data

An embedding technique is presented to estimate standard model tau tau backgrounds from data with minimal simulation input. In the data, the muons are removed from reconstructed mu mu events and replaced with simulated tau leptons with the same kinematic properties. In this way, a set of hybrid events is obtained that does not rely on simulation except for the decay of the tau leptons. The challenges in describing the underlying event or the production of associated jets in the simulation are avoided. The technique described in this paper was developed for CMS. Its validation and the inherent uncertainties are also discussed. The demonstration of the performance of the technique is based on a sample of proton-proton collisions collected by CMS in 2017 at root s = 13 TeV corresponding to an integrated luminosity of 41.5 fb(-1).Peer reviewe

Performance of missing transverse momentum reconstruction in proton-proton collisions at root s=13 TeV using the CMS detector

The performance of missing transverse momentum ((p) over right arrow (miss)(T)) reconstruction algorithms for the CMS experiment is presented, using proton-proton collisions at a center-of-mass energy of 13 TeV, collected at the CERN LHC in 2016. The data sample corresponds to an integrated luminosity of 35.9 fb(-1). The results include measurements of the scale and resolution of (p) over right arrow (miss)(T), and detailed studies of events identified with anomalous (p) over right arrow (miss)(T). The performance is presented of a (p) over right arrow (miss)(T) reconstruction algorithm that mitigates the effects of multiple proton-proton interactions, using the "pileup per particle identification" method. The performance is shown of an algorithm used to estimate the compatibility of the reconstructed (p) over right arrow (miss)(T) with the hypothesis that it originates from resolution effects.Peer reviewe

Late Miocene-early Pleistocene paleoproductivity variations of the Lop Nor in the Tarim Basin and its implications on aridification in Asian Interior

Extensive lacustrine deposits in the eastern Tarim Basin provide records of climate change influenced by the westerly winds and the Asian monsoon. To characterize the evolution of climate change in this region, we analyze elemental concentrations of barium (Ba) from the Ls2 drill core of Lop Nor, a paleo-lakebed located in the eastern Tarim Basin. Biogenic Ba concentrations from this drill core display a large-amplitude oscillation that generally follows a pattern similar to that of Artemisia content and ostracod assemblages, suggesting that is may serve as an index for climate change experienced in the basin. Our results indicate that biogenic Ba is especially sensitive to precipitation. All climatic proxies served in this study vary significantly over late Miocene to early Pleistocene time period. Strong aridification of eastern Tarim in the late Miocene to the early Pliocene may be attributed to a latitudinal shift in the westerly winds, which would have resulted in more moisture transported to southern and eastern Tibet. The growth of the Himalaya and Tibetan Plateau may have acted as an orographic barrier that blocked moisture sourced in the south from the northern margins of the plateau. We link weaker aridification in the late Pliocene to an increased intensity of the Indian Monsoon.</p

A Rb/Sr record of the weathering response to environmental changes in westerly winds across the Tarim Basin in the late Miocene to the early Pleistocene

The long-term record of lacustrine deposits in the Tarim Basin seems to provide a record of climate influenced by westerly winds. To characterize the evolution of westerly winds, we analyzed concentrations of Rb, V, Zn, Sc and Sr for the drill core Ls2 from Lop Nor in the eastern Tarim Basin. The Rb/Sr ratio in lacustrine deposits depends primarily on the Sr element activity during weathering, after the influence of source provenance has been removed. We assume that with such a correction, the Rb/Sr ratio is controlled by precipitation, which depends on moisture transport by westerly winds to the Tarim Basin. The Rb/Sr ratio displays a large-amplitude oscillation that generally follows a pattern similar to that of pollen and ostracod assemblages, which support the inference that rainfall amount affects the Rb/Sr ratio, and in turn suggests that it may serve as an index of precipitation that was transported by westerly wind. All these climatic proxies obviously changed since the late Miocene, suggesting stronger aridification that may be attributed to a latitudinal shift in westerly winds since the late Miocene. A southward migration of westerly winds, which then transported more moisture to the southern and eastern parts of the Tibetan Plateau, agrees with modeling results and the geological record during that time. This event may be causally related to the expansion of the northern hemisphere ice and/or regional tectonic uplift of high mountains around the Tarim Basin.</p

Manipulation of electromagnetically-induced transparency in planar 2 metamaterials based on phase coupling

We experimentally demonstrated a controllable electromagnetically induced transparency (EIT)-like spectral response at microwave frequencies in a planar metamaterial consisting of two identical split-ring resonators (SRRs) with side-by-side symmetry. In our scheme, phase coupling between the two SRRs (serving as the bright mode), which were excited strongly by the incident wave, was employed, and it was found that the EIT-like spectral response could be controlled by simply adjusting the incident angle. Thus, our scheme may be used for electromagnetic-wave switching. A high group index for slow-light application and a high quality factor could be obtained by simply controlling the incident angle