43991782
Spontaneous Casimir Effect
The dynamical Casimir effect predicts that vacuum amplification effects, resulting in the creation of real particles out of vacuum fluctuations, are induced by rapidly modulating the boundary conditions of a quantum field. Here we show that a spontaneous release of virtual photons from the quantum vacuum can occur in a quantum optical system in the ultrastrong coupling regime. In contrast to the dynamical Casimir effect and other pair creation mechanisms, this phenomenon does not require external forces or time dependent parameters. It resembles the production of particles during the early universe expansion induced by the decay of a false vacuum according to inflationary cosmology 1 ar X iv :1 21 0. 23 67 v1 [ qu an tph ] 8 O ct 2 01 2 The dynamical Casimir effect [3] has been recently experimentally realized in a superconducting circuit by modulating the inductance of a quantum interference device at high frequencies [4]. Other proposed vacuum amplification mechanisms [1], as the Schwinger process [12] and the Hawking radiation [13], require the presence of huge external fields or, as the Unruh effect, the presence of a rapidly nonuniformly accelerating observer [14], and have yet to be observed. The here described spontaneous release of virtual photon pairs in the absence of any external drive or observer acceleration resembles the particle production during the universe expansion predicted by modern inflationary cosmology. According to this theory, a scalar field starting in the false vacuum state eventually decays, and the energy that had been locked in it is released to form a hot, uniform soup of particles, which is the assumed starting point of the traditional big bang theory [11]. The Hamiltonian of a realistic atom-cavity system contains so-called counter-rotating terms allowing the simultaneous creation or annihilation of an excitation in both atom and cavity mode. These terms can be safely neglected for small coupling rates ΩR (rotatingwave approximation). However, when ΩR becomes comparable to the cavity resonance frequency of the emitter or the resonance frequency of the cavity mode, the counter-rotating terms are expected to manifest, giving rise to exciting effects in cavity QED [6, 15, 16]. This ultrastrong-coupling regime is difficult to reach in quantum-optical cavity QED, but was recently realized in a variety of solid-state quantum systems [5–10]. Such regime is challenging from a theoretical point of view as the total number of excitations in the cavityemitter system is not preserved, even though its parity is [16]. It has been shown that, in the ultrastrong coupling regime, the quantum optical master equation fails to provide the correct description of the system’s interaction with reservoirs [17]. Moreover quantum optical normal order correlation functions fail to describe photodetection experiments for such systems [18, 19]. Specifically, for a single mode resonator, the photon rate that can be detected by a photoabsorber is no more proportional to 〈a†(t)a(t)〉 (where a and a† are the photon destruction and creation operators) but to 〈X−(t)X+(t)〉, where X(t) is the positive frequency component of the quadrature operator X(t) = a(t) + a†(t) [19]. The most puzzling property of these systems is that their ground state is a squeezed vacuum containing correlated pairs of cavity photons [20]. The photon pairs in the ground state |0̃〉 are, however, virtual and cannot be detected [21], being 〈0̃|X−(t)X+(t)|0̃〉 = 0 [19]. Otherwise, an observation of a stream of photons from such
56319302
THE FORWARD DETECTOR OF THE ANKE SPECTROMETER. SCINTILLATION AND CHERENKOV HODOSCOPES
Central Institute for Nuclear Research, Rossendorf, GermanyThe scintillation and Cherenkov counter system of the forward detector of ANKE, magnetic spec-trometer at the internal beam of the accelerator COSY in Jeulich, is described. The timing and amplitudecharacteristics are presented as well as the capabilities to select physical processes of interest.¶¨¸O¢ ¥E¸O ¸¨¸E¥³ ¸I¨´E¨²²O I¨µ´´OI ¨ I¥·¥´±µ¢¸±¨I ¸I¥EI¨±µ¢ ¶¥·¥¤´¥£µ ¤¥E¥±Eµ· ANKE, ³ £´¨E´µ£µ ¸¶¥±E·µ³¥E· ´ ¢´EE·¥´´¥³ ¶EI±¥ E¸±µ·¨E¥²O COSY ¢ ²¨I¥. ·¨¢¥¤¥´O¨I ¢·¥³¥´´O¥ ¨ ³¶²¨EE¤´O¥ I · ±E¥·¨¸E¨±¨, E ±¦¥ ¢µ§³µ¦´µ¸E¨ ¨I ¶·¨³¥´¥´¨O ¤²O ¢O¤¥²¥´¨O¨´E¥·¥¸EOÐ¨I E¨§¨I¥¸±¨I ¶·µI¥¸¸µ¢.
119445528
Vector and tensor analysing powers in deuteron-proton breakup reactions at intermediate energies
Abstract Vector and tensor analysing powers of the d → p → ( p p ) n (charge-exchange) and d → p → ( p n ) p (non-charge-exchange) breakup reactions have been measured with the ANKE spectrometer at the COSY ring at a deuteron beam energy of 1170 MeV for small momentum transfers to the low excitation energy ( p p ) or ( p n ) systems. A quantitative understanding of the values of A x x and A y y for the charge-exchange reaction is provided by impulse approximation calculations. The data suggest that spin-flip isospin-flip transitions, which dominate the charge-exchange breakup of the deuteron, are also important in the non-charge-exchange reaction.
118789979
Measurement of Subthreshold K+ Production in pA Collisions with ANKE
121039239
Identification of K+-mesons from subthreshold pA collisions with ANKE at COSY-Jülich
Abstract The spectrometer ANKE has been put into operation at the accelerator COSY of the Forschungszentrum Julich in spring 1998. An initial scientific goal is to study K + -production in pA collisions at subthreshold energies far below the free NN-threshold at T p =1.58 GeV. This requires the identification of K + -mesons in a background of pions and protons, about 10 6 times more intense. In this paper the sophisticated detection system and the software procedures for kaon identification are described. With the help of TOF, energy-loss and range measurements as well as the track information from wire chambers, it is possible to measure d 2 σ/ d Ω d p for deep subthreshold K + production at beam energies down to T p =1.0 GeV.
7502590
Inclusive K+-meson production in proton-nucleus interactions
Abstract.The production of K+-mesons in pA (A = D, C, Cu, Ag, Au) collisions has been investigated at the COoler SYnchrotron COSY-Jülich for beam energies Tp = 1.0-2.3 GeV. Double differential inclusive pC cross-sections at forward angles ϑ{K^+} < 12° as well as the target mass dependence of the K+ momentum spectra have been measured with the ANKE spectrometer. Far below the free NN threshold at TNN = 1.58 GeV the spectra reveal a high degree of collectivity in the target nucleus. From the target mass dependence of the cross-sections at higher energies, the repulsive in-medium potential of the K+-mesons can be deduced. Using pN cross-section parameterisations from the literature and our measured pD data we derive a cross-section ratio σ(pn↦K+X)/σ(pp↦K+X) ∼ (3-4).
23095524
μ Eridani from MOST and from the ground: an orbit, the SPB component's fundamental parameters and the SPB frequencies
MOST time-series photometry of mu Eri, an SB1 eclipsing binary with a rapidly-rotating SPB primary, is reported and analyzed. The analysis yields a number of sinusoidal terms, mainly due to the intrinsic variation of the primary, and the eclipse light-curve. New radial-velocity observations are presented and used to compute parameters of a spectroscopic orbit. Frequency analysis of the radial-velocity residuals from the spectroscopic orbital solution fails to uncover periodic variations with amplitudes greater than 2 km/s. A Rossiter-McLaughlin anomaly is detected from observations covering ingress. 
From archival photometric indices and the revised Hipparcos parallax we derive the primary's effective temperature, surface gravity, bolometric correction, and the luminosity. An analysis of a high signal-to-noise spectrogram yields the effective temperature and surface gravity in good agreement with the photometric values. From the same spectrogram, we determine the abundance of He, C, N, O, Ne, Mg, Al, Si, P, S, Cl, and Fe. 
The eclipse light-curve is solved by means of EBOP. For a range of mass of the primary, a value of mean density, very nearly independent of assumed mass, is computed from the parameters of the system. Contrary to a recent report, this value is approximately equal to the mean density obtained from the star's effective temperature and luminosity. 
Despite limited frequency resolution of the MOST data, we were able to recover the closely-spaced SPB frequency quadruplet discovered from the ground in 2002-2004. The other two SPB terms seen from the ground were also recovered. Moreover, our analysis of the MOST data adds 15 low-amplitude SPB terms with frequencies ranging from 0.109 c/d to 2.786 c/d.
14319327
Confirmation of the Planet Hypothesis for the Long-period Radial Velocity Variations of Beta Geminorum
Aims. Our aim is to confirm the nature of the long period radial velocity measurements for β Gem first found by Hatzes & Cochran (1993). Methods. We present precise stellar radial velocity measurements for the K giant star β Gem spanning over 25 years. An examination of the Ca II K emission, spectral line shapes from high resolution data ($R = 210\,000$), and Hipparcos photometry was also made to discern the true nature of the long period radial velocity variations. Results. The radial velocity data show that the long period, low amplitude radial velocity variations found by Hatzes & Cochran (1993) are long-lived and coherent. Furthermore, the Ca II K emission, spectral line bisectors, and Hipparcos photometry show no significant variations of these quantities with the radial velocity period. An orbital solution assuming a stellar mass of 1.7 $M_\odot$ yields a period, $P = 589.6$ days, a minimum mass of 2.3 M Jupiter , and a semi-major axis, $a = 1.6$ AU. The orbit is nearly circular ($e = 0.02$). Conclusions. The data presented here confirm the planetary companion hypothesis suggested by Hatzes & Cochran (1993). β Gem is one of six intermediate mass stars known to host a sub-stellar companion and suggests that planet-formation around stars much more massive than the sun may common.
23202373
Planetary transit candidates in the CoRoT LRa01 field
Context. The space mission CoRoT is devoted to the analysis of stellar variability and the photometric detection of extrasolar planets. Aims. We present the list of planetary transit candidates detected in the first short run observed by CoRoT that targeted SRc01, towards the Galactic center in the direction of Aquila, which lasted from April to May 2007. Methods. Among the acquired data, we analyzed those for 1269 sources in the chromatic bands and 5705 in the monochromatic band. Instrumental noise and the stellar variability were treated with several detrending tools, to which several transit-search algorithms were subsequently applied. Results. Fifty-one sources were classified as planetary transit candidates and 26 were followed up with ground-based observations. Until now, no planet has been detected in the CoRoT data from the SRc01 field.
11989684
Line-profile tomography of exoplanet transits - II. A gas-giant planet transiting a rapidly rotating A5 star
Most of our knowledge of extrasolar planets rests on precise radial-velocity measurements, either for direct detection or for confirmation of the planetary origin of photometric transit signals. This has limited our exploration of the parameter space of exoplanet hosts to solar- and later-type, sharp-lined stars. Here we extend the realm of stars with known planetary companions to include hot, fast-rotating stars. Planet-like transits have previously been reported in the light curve obtained by the SuperWASP survey of the A5 star HD 15082 (WASP–33; V= 8.3, v sin i= 86 km s−1). Here we report further photometry and time-series spectroscopy through three separate transits, which we use to confirm the existence of a gas-giant planet with an orbital period of 1.22 d in orbit around HD 15082. From the photometry and the properties of the planet signal travelling through the spectral line profiles during the transit, we directly derive the size of the planet, the inclination and obliquity of its orbital plane and its retrograde orbital motion relative to the spin of the star. This kind of analysis opens the way to studying the formation of planets around a whole new class of young, early-type stars, hence under different physical conditions and generally in an earlier stage of formation than in sharp-lined late-type stars. The reflex orbital motion of the star caused by the transiting planet is small, yielding an upper mass limit of 4.1 MJupiter on the planet. We also find evidence of a third body of substellar mass in the system, which may explain the unusual orbit of the transiting planet. In HD 15082, the stellar line profiles also show evidence of non-radial pulsations, clearly distinct from the planetary transit signal. This raises the intriguing possibility that tides raised by the close-in planet may excite or amplify the pulsations in such stars.
118383389
Constraining the role of star cluster mergers in nuclear cluster formation: simulations confront integral-field data
We present observations and dynamical models of the stellar nuclear clusters (NCs) at the centres of NGC 4244 and M33. We then compare these to an extensive set of simulations testing the importance of purely stellar dynamical mergers on the formation and growth of NCs. Mergers of star clusters are able to produce a wide variety of observed properties, including densities, structural scaling relations, shapes (including the presence of young discs) and even rapid rotation. None the less, difficulties remain, most notably that the second-order kinematic moment inline image of the models is too centrally peaked to match observations. This can be partially remedied by the merger of star clusters on to a pre-existing nuclear disc, but the line-of-sight velocity V is still more slowly rising than in NGC 4244. Our results therefore suggest that purely stellar dynamical mergers cannot form NCs and that gas dissipation is a necessary ingredient for at least ∼50 per cent of a NC’s mass. The negative vertical anisotropy found in NGC 4244, however, requires at least 10 per cent of the mass to have been accreted as stars, since gas dissipation and in situ star formation leads to positive vertical anisotropy.