Bounds on Cross-sections and Lifetimes for Dark Matter Annihilation and Decay into Charged Leptons from Gamma-ray Observations of Dwarf Galaxies

We provide conservative bounds on the dark matter cross-section and lifetime from final state radiation produced by annihilation or decay into charged leptons, either directly or via an intermediate particle $\phi$. Our analysis utilizes the experimental gamma-ray flux upper limits from four Milky Way dwarf satellites: HESS observations of Sagittarius and VERITAS observations of Draco, Ursa Minor, and Willman 1. Using 90% confidence level lower limits on the integrals over the dark matter distributions, we find that these constraints are largely unable to rule out dark matter annihilations or decays as an explanation of the PAMELA and ATIC/PPB-BETS excesses. However, if there is an additional Sommerfeld enhancement in dwarfs, which have a velocity dispersion ~10 to 20 times lower than that of the local Galactic halo, then the cross-sections for dark matter annihilating through $\phi$'s required to explain the excesses are very close to the cross-section upper bounds from Willman 1. Dark matter annihilation directly into $\tau$'s is also marginally ruled out by Willman 1 as an explanation of the excesses, and the required cross-section is only a factor of a few below the upper bound from Draco. Finally, we make predictions for the gamma-ray flux expected from the dwarf galaxy Segue 1 for the Fermi Gamma-ray Space Telescope. We find that for a sizeable fraction of the parameter space in which dark matter annihilation into charged leptons explains the PAMELA excess, Fermi has good prospects for detecting a gamma-ray signal from Segue 1 after one year of observation.Comment: 11 pages, 4 figures. References added. Final published versio

PARTISANSHIP, TRUMP FAVORABILITY, AND CHANGES IN SUPPORT FOR TRADE

Why has the relationship between partisan identification and Americans’ trade attitudes shifted in recent years? We suggest that recent shifts in trade attitudes among partisans are driven by Donald Trump, who staked out a position on trade that is at odds with the position on trade traditionally held by Republicans. Using panel data from the Voter Study Group (VSG) surveys from 2011, 2016, and 2017, we conduct cross-sectional analyses showing that the relationship between partisanship and trade attitudes has shifted dramatically from 2011 to 2016/2017; in 2011, Republicans were significantly more supportive of expanded trade, but by 2016/2017 the relationship had reversed, with Democrats significantly more supportive of trade. We link changes over time in trade attitudes with how Americans evaluate Trump: individuals with favorable attitudes toward Donald Trump are significantly more likely to shift their attitudes in an anti-trade direction from 2011-2016. Because so many more Republicans have favorable attitudes toward Trump, the aggregate effect of Trump favorability is to shift Republicans as a group to be less favorable toward trade than Democrats. We suggest that Donald Trump has had a transformative effect on Americans’ trade attitudes, with previous supporters (opponents) of expanded trade now expressing opposing (supporting) attitudes

The “Trump” Effect: Political Elite and Support for Free Trade in America

While previous literature has offered two broad categories of explanation for individual trade preferences: economic self-interest and non-economic factors, we contend that during times of intensified elite discourse on trade, individuals may follow elite opinions to form their opinions on trade. Utilizing data from the 2016 American National Election Survey, we examine the effect of Trump’s protectionist views and rhetoric on public trade opinion. We argue that there was a “Trump effect” on trade attitudes among the mass public in 2016 and this effect went beyond the party line, meaning that Trump supporters, regardless of their partisanship, were more likely to be influenced by his protectionist views and to adopt anti-free trade positions. Moreover, we suggest a conditional effect of political knowledge on the “Trump effect” of trade opinion. Our empirical tests offer strong support for both hypotheses, suggesting a significant “Trump effect” on public trade opinion in 2016

Dark Matter and Pseudo-flat Directions in Weakly Coupled SUSY Breaking Sectors

We consider candidates for dark matter in models of gauge mediated supersymmetry breaking, in which the supersymmetry breaking sector is weakly coupled and calculable. Such models typically contain classically flat directions, that receive one-loop masses of a few TeV. These pseudo-flat directions provide a new mechanism to account for the cold dark matter relic abundance. We discuss also the possibility of heavy gravitino dark matter in such models.Comment: 16 pages, 2 figures. v2: comments, refs adde

On the Thermal History of Calculable Gauge Mediation

Many messenger models with realistic gaugino masses are based on meta-stable vacua. In this work we study the thermal history of some of these models. Analyzing R-symmetric models, we point out that while some of the known messenger models clearly prefer the supersymmetric vacuum, there is a vast class of models where the answer depends on the initial conditions. Along with the vacuum at the origin, the high temperature thermal potential also possesses a local minimum far away from the origin. This vacuum has no analog at zero temperature. The first order phase transition from this vacuum into the supersymmetric vacuum is parametrically suppressed, and the theory, starting from that vacuum, is likely to evolve to the desired gauge-mediation vacuum. We also comment on the thermal evolution of models without R-symmetry.Comment: 22 pages. V2: Comments on the SM effects added. Minor corrections. Reference added. Valuable discussion with S. Abel, J. Jaeckel and V. Khoze acknowledged. V3: Types of EOGM explicitly defined in the introduction. Discussions about the phase transitions expanded. Typo corrected. Journal versio

An Electron Fixed Target Experiment to Search for a New Vector Boson A' Decaying to e+e-

We describe an experiment to search for a new vector boson A' with weak coupling alpha' > 6 x 10^{-8} alpha to electrons (alpha=e^2/4pi) in the mass range 65 MeV < m_A' < 550 MeV. New vector bosons with such small couplings arise naturally from a small kinetic mixing of the "dark photon" A' with the photon -- one of the very few ways in which new forces can couple to the Standard Model -- and have received considerable attention as an explanation of various dark matter related anomalies. A' bosons are produced by radiation off an electron beam, and could appear as narrow resonances with small production cross-section in the trident e+e- spectrum. We summarize the experimental approach described in a proposal submitted to Jefferson Laboratory's PAC35, PR-10-009. This experiment, the A' Experiment (APEX), uses the electron beam of the Continuous Electron Beam Accelerator Facility at Jefferson Laboratory (CEBAF) at energies of ~1-4 GeV incident on 0.5-10% radiation length Tungsten wire mesh targets, and measures the resulting e+e- pairs to search for the A' using the High Resolution Spectrometer and the septum magnet in Hall A. With a ~1 month run, APEX will achieve very good sensitivity because the statistics of e+e- pairs will be ~10,000 times larger in the explored mass range than any previous search for the A' boson. These statistics and the excellent mass resolution of the spectrometers allow sensitivity to alpha'/alpha one to three orders of magnitude below current limits, in a region of parameter space of great theoretical and phenomenological interest. Similar experiments could also be performed at other facilities, such as the Mainz Microtron.Comment: 19 pages, 12 figures, 2 table

R-symmetry and Supersymmetry Breaking at Finite Temperature

We analyze the spontaneous $U(1)_R$ symmetry breaking at finite temperature for the simple O'Raifeartaigh-type model introduced in [1] in connection with spontaneous supersymmetry breaking. We calculate the finite temperature effective potential (free energy) to one loop order and study the thermal evolution of the model. We find that the R-symmetry breaking occurs through a second order phase transition. Its associated meta-stable supersymmetry breaking vacuum is thermodynamically favored at high temperatures and the model remains trapped in this state by a potential barrier, as the temperature lowers all the way until T=0.Comment: 19 pages, 4 figures - Minor revisions, references added. To appear in JHE

Rotator cuff tears after 70years of age: A prospective, randomized, comparative study between decompression and arthroscopic repair in 154 patients

SummaryIntroductionArthroscopic repair of rotator cuff tears leads to better clinical outcomes than subacromial decompression alone; however the former is rarely proposed to patients above 70years of age. Our hypothesis was that arthroscopic repair would be superior to decompression in patient 70years or older. The primary goal was to compare the clinical results obtained with each technique. The secondary goal was to analyze the effects of age, tendon retraction and fatty infiltration on the outcome.MethodsThis was a prospective, comparative, randomized, multicenter study where 154 patients were included who were at least 70years of age. Of the included patients, 143 (70 repair and 73 decompression) were seen at one-year follow-up; these patients had an average age of 74.6years. Shoulders had a complete supraspinatus tear with extension limited to the upper-third of the infraspinatus and Patte stage 1 or 2 retraction. Clinical outcomes were evaluated with the Constant, ASES and SST scores.ResultsAll scores improved significantly with both techniques: Constant +33.81 (P<0.001), ASES +52.1 (P<0.001), SST +5.86 (P<0.001). However, repair led to even better results than decompression: Constant (+35.85 vs. +31.8, P<0.05), ASES (+56.09 vs. +48.17, P=0.01), SST (+6.33 vs. +5.38, P=0.02). The difference between repair and decompression was not correlated with age; arthroscopic repair was also better in patients above 75years of age (Constant, ASES and SST scores P<0.01). There was no significant correlation between the final outcomes and initial retraction: Constant (P=0.14), ASES (P=0.92), SST (P=0.47). The difference between repair and decompression was greater in patients with stages 0 and 1 fatty infiltration (Constant P<0.02) than in patients with stages 2 and 3 fatty infiltration (Constant P<0.05).ConclusionThere was a significant improvement in all-clinical scores for both techniques 1year after surgery. Repair was significantly better than decompression for all clinical outcomes, even in patients above 75years of age. The difference observed between repair and decompression was greater in patients with more retracted tears and lesser in patients with more severe fatty infiltration.Level of proofII (prospective, randomized study with low power)