Optimization of Bell's Inequality Violation For Continuous Variable Systems

Two mode squeezed vacuum states allow Bell's inequality violation (BIQV) for all non-vanishing squeezing parameter $(\zeta)$. Maximal violation occurs at $\zeta \to \infty$ when the parity of either component averages to zero. For a given entangled {\it two spin} system BIQV is optimized via orientations of the operators entering the Bell operator (cf. S. L. Braunstein, A. Mann and M. Revzen: Phys. Rev. Lett. {\bf68}, 3259 (1992)). We show that for finite $\zeta$ in continuous variable systems (and in general whenever the dimensionality of the subsystems is greater than 2) additional parameters are present for optimizing BIQV. Thus the expectation value of the Bell operator depends, in addition to the orientation parameters, on configuration parameters. Optimization of these configurational parameters leads to a unique maximal BIQV that depends only on $\zeta.$ The configurational parameter variation is used to show that BIQV relation to entanglement is, even for pure state, not monotonic.Comment: An example added; shows that the amount of Bell's inequality violation as a measure of entanglement is doubtfu

Decoherence of domains and defects at phase transitions

In this further letter on the onset of classical behaviour in field theory due to a phase transition, we show that it can be phrased easily in terms of the decoherence functional, without having to use the master equation. To demonstrate this, we consider the decohering effects due to the displacement of domain boundaries, with implications for the displacement of defects, in general. We see that decoherence arises so quickly in this event, that it is negligible in comparison to decoherence due to field fluctuations in the way defined in our previous papers.Comment: Version published in Phys. Lett.

Associations of depression and anxiety symptoms with sexual behaviour in women and heterosexual men attending sexual health clinics: a cross-sectional study.

OBJECTIVE: To assess the association of symptoms of depression and anxiety with sexual risk behaviour and history, among women and heterosexual men attending genitourinary medicine (GUM) clinics. METHODS: Attitudes to and Understanding of Risk of Acquisition of HIV (AURAH) was a cross-sectional, self-administered questionnaire study recruited from 20 GUM clinics in England, 2013-2014. This analysis included women and heterosexual men. The prevalence of depression and anxiety symptoms was assessed. Modified Poisson regression was used to produce adjusted prevalence ratios (aPR) for the association of t demographic, socioeconomic and lifestyle factors with depression and anxiety, adjusted for gender, age, ethnicity, education level and study region. Among individuals reporting sex in the past 3 months, associations of depression and anxiety with sexual risk behaviour and history were assessed separately by gender, adjusted for age, ethnicity, study region, education and relationship status. RESULTS: Questionnaires were completed by 676 women and 470 heterosexual men. Depression symptoms were reported by 100 (14.8%) women and 33 men (7.0%). Anxiety symptoms were reported by 79 women (11.7%) and 21 men (4.5%). Among women reporting recent sex, those with depression symptoms were more likely to report condomless sex with a non-regular partner, aPR 1.38 (1.07-1.77) and recent condomless sex with two or more partners, 1.80 (1.25-2.59). Women with anxiety symptoms more likely to report recent condomless sex with two or more partners, 1.68 (1.13-2.50), low self-efficacy for condom use, 1.54 (1.02-2.31) and STI diagnosis in the last year 1.51 (1.04-2.20). Among heterosexual men reporting recent sex, depression and anxiety symptoms were associated with low self-efficacy with condom use, 2.32 (1.29-4.19) for depression and 2.23 (1.26-3.94) for anxiety, but not with measures of condomless sex. DISCUSSION: The associations between psychological symptoms and sexual risk behaviours highlight the importance of holistic assessment of need by both general and sexual health clinicians. We highlight the challenge in delivering holistic care associated with fragmentation of sexual health services

Measurement of the View the tt production cross-section using eμ events with b-tagged jets in pp collisions at √s = 13 TeV with the ATLAS detector

This paper describes a measurement of the inclusive top quark pair production cross-section (σtt¯) with a data sample of 3.2 fb−1 of proton–proton collisions at a centre-of-mass energy of √s = 13 TeV, collected in 2015 by the ATLAS detector at the LHC. This measurement uses events with an opposite-charge electron–muon pair in the final state. Jets containing b-quarks are tagged using an algorithm based on track impact parameters and reconstructed secondary vertices. The numbers of events with exactly one and exactly two b-tagged jets are counted and used to determine simultaneously σtt¯ and the efficiency to reconstruct and b-tag a jet from a top quark decay, thereby minimising the associated systematic uncertainties. The cross-section is measured to be: σtt¯ = 818 ± 8 (stat) ± 27 (syst) ± 19 (lumi) ± 12 (beam) pb, where the four uncertainties arise from data statistics, experimental and theoretical systematic effects, the integrated luminosity and the LHC beam energy, giving a total relative uncertainty of 4.4%. The result is consistent with theoretical QCD calculations at next-to-next-to-leading order. A fiducial measurement corresponding to the experimental acceptance of the leptons is also presented

Search for strong gravity in multijet final states produced in pp collisions at √s=13 TeV using the ATLAS detector at the LHC

A search is conducted for new physics in multijet final states using 3.6 inverse femtobarns of data from proton-proton collisions at √s = 13TeV taken at the CERN Large Hadron Collider with the ATLAS detector. Events are selected containing at least three jets with scalar sum of jet transverse momenta (HT) greater than 1TeV. No excess is seen at large HT and limits are presented on new physics: models which produce final states containing at least three jets and having cross sections larger than 1.6 fb with HT > 5.8 TeV are excluded. Limits are also given in terms of new physics models of strong gravity that hypothesize additional space-time dimensions

Search for TeV-scale gravity signatures in high-mass final states with leptons and jets with the ATLAS detector at sqrt [ s ] = 13TeV

A search for physics beyond the Standard Model, in final states with at least one high transverse momentum charged lepton (electron or muon) and two additional high transverse momentum leptons or jets, is performed using 3.2 fb−1 of proton–proton collision data recorded by the ATLAS detector at the Large Hadron Collider in 2015 at √s = 13 TeV. The upper end of the distribution of the scalar sum of the transverse momenta of leptons and jets is sensitive to the production of high-mass objects. No excess of events beyond Standard Model predictions is observed. Exclusion limits are set for models of microscopic black holes with two to six extra dimensions

Operation and performance of the ATLAS semiconductor tracker

The semiconductor tracker is a silicon microstrip detector forming part of the inner tracking system of the ATLAS experiment at the LHC. The operation and performance of the semiconductor tracker during the first years of LHC running are described. More than 99% of the detector modules were operational during this period, with an average intrinsic hit efficiency of (99.74±0.04)%. The evolution of the noise occupancy is discussed, and measurements of the Lorentz angle, δ-ray production and energy loss presented. The alignment of the detector is found to be stable at the few-micron level over long periods of time. Radiation damage measurements, which include the evolution of detector leakage currents, are found to be consistent with predictions and are used in the verification of radiation background simulations