Physik - Open Access LMU - Teil 02/02

Fri, 1 Jan 2016 12:00:00 +0100 https://epub.ub.uni-muenchen.de/28963/1/MPTL2015_Selected_Papers.pdf Unbekannter Autor

Fri, 1 Jan 2016 12:00:00 +0100 https://epub.ub.uni-muenchen.de/29030/7/MPTL20_Proceedings.pdf Unbekannter Autor

We present here an application of the recently developed hybrid coupled channels approach to study photo-ionization of noble gas atoms: Neon and Argon. We first compute multi-photon ionization rates and cross-sections for these inert gas atoms with our approach and compare them with reliable data available from R-matrix Floquet theory. The good agreement between coupled channels and R-matrix Floquet theory show that our method treats multi-electron systems on par with the well established R-matrix theory. We then apply the time dependent surface flux (tSURFF) method with our approach to compute total and angle resolved photo-electron spectra from Argon with linearly and circularly polarized 12 nm wavelength laser fields, a typical wavelength available from Free Electron Lasers (FELs)

Linear depolarization ratios in clean air ranges were measured with POLIS-6 at 355 and 532 nm. The mean deviation from the theoretical values, including the rotational Raman lines within the filter bandwidths, amounts to 0.0005 at 355 nm and to 0.0012 at 532 nm. The mean uncertainty of the measured linear depolarization ratio of clean air is about 0.0005 at 355 nm and about 0.0006 at 532 nm.

Linear depolarization ratios in clean air ranges were measured with POLIS-6 at 355 and 532 nm. The mean deviation from the theoretical values, including the rotational Raman lines within the filter bandwidths, amounts to 0.0005 at 355 nm and to 0.0012 at 532 nm. The mean uncertainty of the measured linear depolarization ratio of clean air is about 0.0005 at 355 nm and about 0.0006 at 532 nm.

UV excitation of the DNA single strand (dT)(18) leads to electronically excited states that are potential gateways to DNA photolesions. Using time-resolved infrared spectroscopy we characterized a species with a lifetime of similar to 100 ps and identified it as a charge separated excited state between two thymine bases.

It has been known for about sixty years that proton and heavy ion therapy is a very powerful radiation procedure for treating tumors. It has an innate ability to irradiate tumors with greater doses and spatial selectivity compared with electron and photon therapy and, hence, is a tissue sparing procedure. For more than twenty years, powerful lasers have generated high energy beams of protons and heavy ions and it has, therefore, frequently been speculated that lasers could be used as an alternative to radiofrequency (RF) accelerators to produce the particle beams necessary for cancer therapy. The present paper reviews the progress made towards laser driven hadron cancer therapy and what has still to be accomplished to realize its inherent enormous potential.

Performing far-field microscope polarization spectroscopy and finite element method simulations, we investigated experimentally and theoretically the surface plasmon modes in single Ag nanowire antennas. Our results show that the surface plasmon resonances in the single Ag nanowire antenna can be tuned from the dipole plasmon mode to a higher order plasmon mode, which would result in the emission with different intensities and polarization states, for the semiconductor quantum dots coupled to the nanowire antenna. The fluorescence polarization is changed with different polarized excitation of the 800 nm light beam, while it remains parallel to the Ag nanowire axis at the 400 nm excitation. The 800 nm incident tight interacts nonresonantly with the dipole plasmon mode with the polarized excitation parallel to the Ag nanowire axis, while it excites a higher order plasmon mode with the perpendicular excitation. Under excitation of 400 nm, either the parallel or perpendicular excitation can only result in a dipole plasmon mode. In addition, we demonstrate that the single Ag nanowire antenna can work as an energy concentrator for enhancing the two-photon excited fluorescence of semiconductor quantum dots.

Many problems caused by bacterial biofilms can be traced back to their high resilience towards chemical perturbations and their extraordinary sturdiness towards mechanical forces. However, the molecular mechanisms that link the mechanical properties of a biofilm with the ability of bacteria to survive in different chemical environments remain enigmatic. Here, we study the erosion stability of Bacillus subtilis (B. subtilis) biofilms in the presence of different chemical environments. We find that these biofilms can utilize the absorption of certain metal ions such as Cu2+, Zn2+, Fe2+, Fe3+ and Al3+ into the biofilm matrix to avoid erosion by shear forces. Interestingly, many of these metal ions are toxic for planktonic B. subtilis bacteria. However, their toxic activity is suppressed when the ions are absorbed into the biofilm matrix. Our experiments clearly demonstrate that the biofilm matrix has to fulfill a dual function, i.e. regulating both the mechanical properties of the biofilm and providing a selective barrier towards toxic chemicals.

The ionization and fragmentation dynamics of iodine molecules (I-2) are traced using very intense (similar to 10(14) W cm(-2)) ultra-short (similar to 60 fs) light pulses with 87 eV photons of the Free-electron LASer at Hamburg (FLASH) in combination with a synchronized femtosecond optical laser. Within a pump-probe scheme the IR pulse initiates a molecular fragmentation and then, after an adjustable time delay, the system is exposed to an intense FEL pulse. This way we follow the creation of highly-charged molecular fragments as a function of time, and probe the dynamics of multi-photon absorption during the transition from a molecule to individual atoms.

AFM-based dynamic single-molecule force spectroscopy was used to stretch carboxymethylated amylose (CMA) polymers, which have been covalently tethered between a silanized glass substrate and a silanized AFM tip via acid-catalyzed ester condensation at pH 2.0. Rupture forces were measured as a function of temperature and force loading rate in the force-ramp mode. The data exhibit significant statistical scattering, which is fitted with a maximum likelihood estimation (MLE) algorithm. Bond rupture is described with a Morse potential based Arrhenius kinetics model. The fit yields a bond dissociation energy De = 35 kJ mol−1 and an Arrhenius pre-factor A = 6.6 × 104 s−1. The bond dissociation energy is consistent with previous experiments under identical conditions, where the force-clamp mode was employed. However, the bi-exponential decay kinetics, which the force-clamp results unambiguously revealed, are not evident in the force-ramp data. While it is possible to fit the force-ramp data with a bi-exponential model, the fit parameters differ from the force-clamp experiments. Overall, single-molecule force spectroscopy in the force-ramp mode yields data whose information content is more limited than force-clamp data. It may, however, still be necessary and advantageous to perform force-ramp experiments. The number of successful events is often higher in the force-ramp mode, and competing reaction pathways may make force-clamp experiments impossible.

Micro-patterned surfaces are frequently used in high-throughput single-cell studies, as they allow one to image isolated cells in defined geometries. Commonly, cells are seeded in excess onto the entire chip, and non-adherent cells are removed from the unpatterned sectors by rinsing. Here, we report on the phenomenon of cellular self-organization, which allows for autonomous positioning of cells on micro-patterned surfaces over time. We prepared substrates with a regular lattice of protein-coated adhesion sites surrounded by PLL-g-PEG passivated areas, and studied the time course of cell ordering. After seeding, cells randomly migrate over the passivated surface until they find and permanently attach to adhesion sites. Efficient cellular self-organization was observed for three commonly used cell lines (HuH7, A549, and MDA-MB-436), with occupancy levels typically reaching 40-60% after 3-5 h. The time required for sorting was found to increase with increasing distance between adhesion sites, and is well described by the time-to-capture in a random-search model. Our approach thus paves the way for automated filling of cell arrays, enabling high-throughput single-cell analysis of cell samples without losses.

The photo-physical properties of 2-(1-ethynylpyrene)-adenosine (PyA), a fluorescent probe for RNA dynamics, were examined by solvation studies. The excited-state dynamics display the influence of the vicinity on the spectral features. Combining improved transient absorption and streak camera measurements along with a new analysis method provide a detailed molecular picture of the photophysics. After intramolecular vibrational energy redistribution (IVR), two distinct states are observed. Solvent class (protic/aprotic) and permittivity strongly affect the properties of these states and their population ratio. As a result their emission spectrum is altered, while the fluorescence quantum yield and the overall lifetime remain nearly unchanged. Consequently, the hitherto existing model of the photophysics is herein refined and extended. The findings can serve as basis for improving the information content of measurements with PyA as a label in RNA.

Wed, 1 Jan 2014 12:00:00 +0100 https://epub.ub.uni-muenchen.de/24199/1/oa_24199.pdf Aielli, G.; Ahmadov, F.; Ahmad, A.; Ahlen, S. P.; Agustoni, M.; Aguilar-Saavedra, J. A.; Agatonovic-Jovin, T.; Adye, T.; Adomeit, Stefanie; Adelman, J.; Addy, T. N.; Adams, D. L.; Adamczyk, L.; Acharya, B. S.; Abulaitia, Y.; Abreu, H.; Abramowicz, H.; AbouZeid, O. S.; Abolins, M.; Abi, B.; Aben, R.; Abdinov, O.; Abdel Khalek, S.; Abdallah, J.; Abbott, B.; Abajyan, T.; Aad, G.

The nu g(9/2), d(5/2), s(1/2) orbitals are assumed to be responsible for the swift onset of collectivity observed in the region below Ni-68. Especially the single-particle energies and strengths of these orbitals are of importance. We studied such properties in the nearby Ni-67 nucleus, by performing a (d, p)-experiment in inverse kinematics employing a post-accelerated radioactive ion beam (RIB) at the REX-ISOLDE facility. The experiment was performed at an energy of 2.95 MeV/u using a combination of the T-REX particle detectors, the Miniball gamma-detection array and a newly-developed delayed-correlation technique as to investigate mu s-isomers. Angular distributions of the ground state and multiple excited states in 67Ni were obtained and compared with DWBA cross-section calculations, leading to the identification of positive-parity states with substantial nu g(9/2) (1007keV) and nu d(5/2) (2207 keV and 3277 keV) single-particle strengths up to an excitation energy of 5.8 MeV. 50 of the nu d(5/2) single-particle strength relative to the nu g(9/2)-orbital is concentrated in and shared between the first two observed 5/2(+) levels. A comparison with extended Shell Model calculations and equivalent (He-3, d) studies in the region around Zr-90(40)50 highlights similarities for the strength of the negative-parity pf and positive-parity g(9/2) state, but differences are observed for the d(5/2) single-particle strength. (C) 2014 The Authors. Published by Elsevier B.V.

Motivated by the construction of spectral manifolds in noncommutative geometry, we introduce a higher degree Heisenberg commutation relation involving the Dirac operator and the Feynman slash of scalar fields. This commutation relation appears in two versions, one sided and two sided. It implies the quantization of the volume. In the one-sided case it implies that the manifold decomposes into a disconnected sum of spheres which will represent quanta of geometry. The two sided version in dimension 4 predicts the two algebras M 2(ℍ) and M 4(ℂ) which are the algebraic constituents of the Standard Model of particle physics. This taken together with the non-commutative algebra of functions allows one to reconstruct, using the spectral action, the Lagrangian of gravity coupled with the Standard Model. We show that any connected Riemannian Spin 4-manifold with quantized volume > 4 (in suitable units) appears as an irreducible representation of the two-sided commutation relations in dimension 4 and that these representations give a seductive model of the “particle picture” for a theory of quantum gravity in which both the Einstein geometric standpoint and the Standard Model emerge from Quantum Mechanics. Physical applications of this quantization scheme will follow in a separate publication.

If electroweak symmetry breaking is driven by a new strongly coupled dynamical sector, one expects the bound states to appear at the TeV scale or slightly below. However, electroweak precision data imposes severe constraints on most of the existing models, putting them under strain. Conventional models require the newcomposite states to come in pairs of rather heavy, close to degenerate spin-1 resonances. In this paper I argue that spin-1 states can actually be lighter without clashing with experimental bounds. As an example, I consider a composite model with a light pseudovector resonance that couples to the Standard Model gauge boson, fermion, and scalar fields. I show how such a resonance leaves basically no imprint on the NLO corrections to the Standard Model. This happens not through parameter tuning, but rather as a consequence of generic properties of realistic UV completions. This pseudovector is mostly unconstrained by existing data and could be as light as 600 GeV. In the last part of the paper I briefly discuss its most characteristic signatures for direct detection at colliders.

We discuss the systematics of power counting in general effective field theories, focusing on those that are nonrenormalizable at leading order. As an illuminating example we consider chiral perturbation theory gauged under the electromagnetic U(1) symmetry. This theory describes the low-energy interactions of the octet of pseudo-Goldstone bosons in QCD with photons and has been discussed extensively in the literature. Peculiarities of the standard approach are pointed out and it is shown how these are resolved within our scheme. The presentation follows closely our recent discussion of power counting for the electroweak chiral Lagrangian. The systematics of the latter is reviewed and shown to be consistent with the concept of chiral dimensions. The results imply that naive dimensional analysis (NDA) is incomplete in general effective field theories, while still reproducing the correct counting in special cases.

We consider the Standard Model, including a light scalar boson h, as an effective theory at the weak scale v = 246 GeV of some unknown dynamics of electroweak symmetry breaking. This dynamics may be strong, with h emerging as a pseudo-Goldstone boson. The symmetry breaking scale Λ is taken to be at 4 π v or above. We review the leading-order Lagrangian within this framework, which is nonrenormalizable in general. A chiral Lagrangian can then be constructed based on a loop expansion. A systematic power counting is derived and used to identify the classes of counterterms that appear at one loop order. With this result the complete Lagrangian is constructed at next-to-leading order, O ( v 2 / Λ 2 ) . This Lagrangian is the most general effective description of the Standard Model containing a light scalar boson, in general with strong dynamics of electroweak symmetry breaking. Scenarios such as the {SILH} ansatz or the dimension-6 Lagrangian of a linearly realized Higgs sector can be recovered as special cases.

We compute the fully differential rate for the Higgs-boson decay h→Zℓ+ℓ− , with Z→ℓ′+ℓ′− . For these processes we assume the most general matrix elements within an effective Lagrangian framework. The electroweak chiral Lagrangian we employ assumes minimal particle content and Standard Model gauge symmetries, but it is otherwise completely general. We discuss how information on new physics in the decay form factors may be obtained that is inaccessible in the dilepton-mass spectrum integrated over angular variables. The form factors are related to the coefficients of the effective Lagrangian, which are used to estimate the potential size of new-physics effects.

In a recent article, we have shown how quantum fluctuations of the background geometry modify Hawking's density matrix for black hole (BH) radiation. Hawking's diagonal matrix picks up small off-diagonal elements whose influence becomes larger with the number of emitted particles. We have calculated the "time-of-first-bit", when the first bit of information comes out of the BH, and the "transparency time", when the rate of information release becomes order unity. We have found that the transparency time is equal to the "Page time" when the BH has lost half of its initial entropy to the radiation, in agreement with Page's results. Here, we improve our previous calculation by keeping track of the time of emission of the Hawking particles and their back-reaction on the BH. Our analysis reveals a new time scale, the radiation "coherence time", which is equal to the geometric mean of the evaporation time and the light crossing time. We find, as for our previous treatment, that the time-of-first-bit is equal to the coherence time, which is much shorter than the Page time. But the transparency time is now much later than the Page time, just one coherence time before the end of evaporation. Close to the end, when the BH is parametrically of Planckian dimensions but still large, the coherence time becomes parametrically equal to the evaporation time, thus allowing the radiation to purify. We also determine the time dependence of the entanglement entropy of the early and late-emitted radiation. This entropy is small during most of the lifetime of the BH, but our qualitative analysis suggests that it becomes parametrically maximal near the end of evaporation.

We calculate, using our recently proposed semiclassical framework, the quantum state of the Hawking pairs that are produced during the evaporation of a black hole (BH). Our framework adheres to the standard rules of quantum mechanics and incorporates the quantum fluctuations of the collapsing shell spacetime in Hawking's original calculation, while accounting for back-reaction effects. We argue that the negative-energy Hawking modes need to be regularly integrated out; and so these are effectively subsumed by the BH and, as a result, the number of coherent negative-energy modes N-coh at any given time is parametrically smaller than the total number of the Hawking particles N-total emitted during the lifetime of the BH. We find that N-coh is determined by the width of the BH wavefunction and scales as the square root of the BH entropy. We also find that the coherent negative-energy modes are strongly entangled with their positive-energy partners. Previously, we have found that Ncoh is also the number of coherent outgoing particles and that information can be continually transferred to the outgoing radiation at a rate set by N-coh. Our current results show that, while the BH is semiclassical, information can be released without jeopardizing the nearly maximal inside-out entanglement and imply that the state of matter near the horizon is approximately the vacuum. The BH firewall proposal, on the other hand, is that the state of matter near the horizon deviates substantially from the vacuum, starting at the Page time. We find that, under the usual assumptions for justifying the formation of a firewall, one does indeed form at the Page time. However, the possible loophole lies in the implicit assumption that the number of strongly entangled pairs can be of the same order of N-total.

We reformulate the quantum black hole portrait in the language of modern condensed matter physics. We show that black holes can be understood as a graviton Bose-Einstein condensate at the critical point of a quantum phase transition, identical to what has been observed in systems of cold atoms. The Bogoliubov modes that become degenerate and nearly gapless at this point are the holographic quantum degrees of freedom responsible for the black hole entropy and the information storage. They have no (semi)classical counterparts and become inaccessible in this limit. These findings indicate a deep connection between the seemingly remote systems and suggest a new quantum foundation of holography. They also open an intriguing possibility of simulating black hole information processing in table-top labs.

We investigate orbifold and smooth Calabi-Yau compactifications of the non-supersymmetric heterotic SO(16)×SO(16) string. We focus on such Calabi-Yau backgrounds in order to recycle commonly employed techniques, like index theorems and cohomology theory, to determine both the fermionic and bosonic 4D spectra. We argue that the N=0 theory never leads to tachyons on smooth Calabi-Yaus in the large volume approximation. As twisted tachyons may arise on certain singular orbifolds, we conjecture that such tachyonic states are lifted in the full blow-up. We perform model searches on selected orbifold geometries. In particular, we construct an explicit example of a Standard Model-like theory with three generations and a single Higgs field.

We evaluate string one-loop contributions to the Kähler metric of closed string moduli in toroidal minimally supersymmetric (Calabi-Yau) orientifolds with D-branes. We focus on the poorly understood N = 1 sectors that receive contributions from all massive string states.

Wed, 1 Jan 2014 12:00:00 +0100 https://epub.ub.uni-muenchen.de/24216/1/oa_24216.pdf Dyk, Danny van; Bobeth, Christoph; Beaujean, Frederik

The available data on | Delta B| = | Delta S| = 1 decays are in good agreement with the Standard Model when permitting subleading power corrections of about 15 at large hadronic recoil. Constraining new- physics effects in C7, C9, C10, the data still demand the same size of power corrections as in the StandardModel. In the presence of chirality- flipped operators, all but one of the power corrections reduce substantially. The Bayes factors are in favor of the Standard Model. Using new lattice inputs for B. K* form factors and under our minimal prior assumption for the power corrections, the favor shifts towardmodelswith chirality- flipped operators. We use the data to further constrain the hadronic form factors in B. K and B. K* transitions.

We discuss quantum corrections to extremal black brane solutions in N = 2 U(1) gauged supergravity in four dimensions. We consider modifications due to a certain class of higher-derivative terms as well as perturbative corrections to the prepotential. We use the entropy function formalism to assess the impact of these corrections on singular brane solutions and we give a few examples. We then use first-order flow equations to construct solutions that interpolate between quantum corrected fixed points of the associated potentials.

We consider the geometric and non-geometric faces of closed string vacua arising by T-duality from principal torus bundles with constant H-flux and pay attention to their double phase space description encompassing all toroidal coordinates, momenta and their dual on equal footing. We construct a star-product algebra on functions in phase space that is manifestly duality invariant and substitutes for canonical quantization. The 3-cocycles of the Abelian group of translations in double phase space are seen to account for non-associativity of the star-product. We also provide alternative cohomological descriptions of non-associativity and draw analogies with the quantization of point-particles in the field of a Dirac monopole or other distributions of magnetic charge. The magnetic field analogue of the R-flux string model is provided by a constant uniform distribution of magnetic charge in space and non-associativity manifests as breaking of angular symmetry. The Poincare vector comes to rescue angular symmetry as well as associativity and also allow for quantization in terms of operators and Hilbert space only in the case of charged particles moving in the field of a single magnetic monopole.

Compactifications of heterotic theories on smooth Calabi-Yau manifolds remain one of the most promising approaches to string phenomenology. In two previous papers, arXiv:1106.4804 and arXiv:1202.1757, large classes of such vacua were constructed, using sums of line bundles over complete intersection Calabi-Yau manifolds in products of projective spaces that admit smooth quotients by finite groups. A total of 1012 different vector bundles were investigated which led to 202 SU(5) Grand Unified Theory (GUT) models. With the addition of Wilson lines, these in turn led, by a conservative counting, to 2122 heterotic standard models. In the present paper, we extend the scope of this programme and perform an exhaustive scan over the same class of models. A total of 1040 vector bundles are analysed leading to 35, 000 SU(5) GUT models. All of these compactifications have the right field content to induce low-energy models with the matter spectrum of the supersymmetric standard model, with no exotics of any kind. The detailed analysis of the resulting vast number of heterotic standard models is a substantial and ongoing task in computational algebraic geometry.

Exclusive production of the isoscalar vector mesons omega and phi is measured with a 190 GeV/c proton beam impinging on a liquid hydrogen target. Cross section ratios are determined in three intervals of the Feynman variable x(F) of the fast proton. A significant violation of the OZI rule is found, confirming earlier findings. Its kinematic dependence on xF and on the invariant mass M-pV of the system formed by fast proton p(fast) and vector meson V is discussed in terms of diffractive production of p(fast) V resonances in competition with central production. The measurement of the spin density matrix element rho(00) of the vector mesons in different selected reference frames provides another handle to distinguish the contributions of these two major reaction types. Again, dependences of the alignment on x(F) and on M-pV are found. Most of the observations can be traced back to the existence of several excited baryon states contributing to omega production which are absent in the case of the phi meson. Removing the low-mass M-pV resonant region, the OZI rule is found to be violated by a factor of eight, independently of x(F).

Spin-averaged asymmetries in the azimuthal distributions of positive and negative hadrons produced in deep inelastic scattering were measured using the CERN SPS longitudinally polarised muon beam at 160 GeV/c and a (LiD)-Li-6 target. The amplitudes of the three azimuthal modulations cos phi(h), cos 2 phi(h) and sin phi(h) were obtained binning the data separately in each of the relevant kinematic variables x, z or p(T)(h), and binning in a three-dimensional grid of these three variables. The amplitudes of the cos phi(h) and cos 2 phi(h) modulations show strong kinematic dependencies both for positive and negative hadrons.

A measurement of the azimuthal asymmetry in dihadron production in deep-inelastic scattering of muons on transversely polarised proton (NH3) targets is presented. They provide independent access to the transversity distribution functions through the measurement of the Collins asymmetry in single hadron production. The data were taken in the year 2010 with the COMPASS spectrometer using a 160 GeV/c muon beam of the CERN SPS, increasing by a factor of about four the overall statistics with respect to the previously published data taken in the year 2007. The measured sizeable asymmetry is in good agreement with the published data. An approximate equality of the Collins asymmetry and the dihadron asymmetry is observed, suggesting a common physical mechanism in the underlying fragmentation. (C) 2014 The Authors. Published by Elsevier B.V.

Non-geometric string backgrounds were proposed to be related to a nonassociative deformation of the space-time geometry. In the flux formulation of double field theory (DFT), the structure of mathematically possible non-associative deformations is analyzed in detail. It is argued that on-shell there should not be any violation of associativity in the effective DFT action. For imposing either the strong or the weaker closure constraint we discuss two possible non-associative deformations of DFT featuring two different ways how on-shell associativity can still be kept.

Exclusive production of rho(0) mesons was studied at the COMPASS experiment by scattering 160 GeV/c muons off transversely polarised protons. Five single-spin and three double-spin azimuthal asymmetries were measured as a function of Q(2), x(Bj), or p(T)(2). The sin Os asymmetry is found to be -0.019 +/- 0.008(stat.) +/- 0.003(syst.). All other asymmetries are also found to be of small magnitude and consistent with zero within experimental uncertainties. Very recent calculations using a GPD-based model agree well with the present results. The data is interpreted as evidence for the existence of chiral-odd, transverse generalized parton distributions.

Gravitational backgrounds, such as black holes, AdS, de Sitter and inflationary universes, should be viewed as composite of N soft constituent gravitons. It then follows that such systems are close to quantum criticality of graviton Bose-gas to Bose-liquid transition. Generic properties of the ordinary metric description, including geodesic motion or particle-creation in the background metric, emerge as the large-N limit of quantum scattering of constituent longitudinal gravitons. We show that this picture correctly accounts for physics of large and small black holes in AdS, as well as reproduces well-known inflationary predictions for cosmological parameters. However, it anticipates new effects not captured by the standard semi-classical treatment. In particular, we predict observable corrections that are sensitive to the inflationary history way beyond last 60 e-foldings. We derive an absolute upper bound on the number of e-foldings, beyond which neither de Sitter nor inflationary Universe can be approximated by a semi-classical metric. However, they could in principle persist in a new type of quantum eternity state. We discuss implications of this phenomenon for the cosmological constant problem.

We regulate Witten's open superstring field theory by replacing the picturechanging insertion at the midpoint with a contour integral of picture changing insertions over the half-string overlaps of the cubic vertex. The resulting product between string fields is non-associative, but we provide a solution to the A(infinity) relations defining all higher vertices. The result is an explicit covariant superstring field theory which by construction satisfies the classical BV master equation.

The production of single photons using rephased amplified spontaneous emission is examined. This process produces single photons on demand with high efficiency by detecting the spontaneous emission from an atomic ensemble, then applying a population-inverting pulse to rephase the ensemble and produce a photon echo of the spontaneous emission events. The theoretical limits on the efficiency of the production are determined for several variants of the scheme. For an ensemble of uniform optical density, generating the initial spontaneous emission and its echo using transitions of different strengths is shown to produce single photons at 70 efficiency, limited by reabsorption. Tailoring the spatial and spectral density of the atomic ensemble is then shown to prevent reabsorption of the rephased photon, resulting in emission efficiency near unity.

Financial crises appear throughout human history. While there are many schools of thought on what the actual causes of such crises are, it has been suggested that the creation of credit money might be a source of financial instability. We discuss how the credit mechanism in a system of fractional reserve banking leads to non-local transfers of purchasing power that also affect non-involved agents. To overcome this issue, we impose the local symmetry of time homogeneity on the monetary system. A bi-currency system of non-bank assets (money) and bank assets (antimoney) is considered. A payment is either made by passing on money or by receiving antimoney. As a result, a free floating exchange rate between non-bank assets and bank assets is established. Credit creation is replaced by the simultaneous transfer of money and antimoney at a negotiated exchange rate. This is in contrast to traditional discussions of full reserve banking, which stalls creditary lending. With money and antimoney, the problem of credit crunches is mitigated while a full time symmetry of the monetary system is maintained. As a test environment for such a monetary system, we discuss an economy of random transfers. Random transfers are a strong criterion to probe the stability of monetary systems. The analysis using statistical physics provides analytical solutions and confirms that a money-antimoney system could be functional. Equally important to the probing of the stability of such a monetary system is the question of how to implement the credit default dynamics. This issue remains open.

Highly efficient single-photon sources (SPS) can increase the secure key rate of quantum key distribution (QKD) systems compared to conventional attenuated laser systems. Here we report on a free space QKD test using an electrically driven quantum dot single-photon source (QD SPS) that does not require a separate laser setup for optical pumping and thus allows for a simple and compact SPS QKD system. We describe its implementation in our 500 m free space QKD system in downtown Munich. Emulating a BB84 protocol operating at a repetition rate of 125 MHz, we could achieve sifted key rates of 5-17 kHz with error ratios of 6-9 and g((2))(0)-values of 0.39-0.76.

Measurements of sulphur isotopes in presolar grains can help to identify the astrophysical sites in which these grains were formed. A more precise thermonuclear rate of the 33S(p, γ)34Cl reaction is required, however, to assess the diagnostic ability of sulphur isotopic ratios. We have studied the 33S(3He,d)34Cl proton-transfer reaction at 25MeV using a high-resolution quadrupole–dipole–dipole–dipole magnetic spectrograph. Deuteron spectra were measured at ten scattering angles between 10◦and 55◦. Twenty-four levels in 34Cl over Ex=4.6–5.9MeVwere observed, including three levels for the first time. Proton spectroscopic factors were extracted for the first time for levels above the 33S+p threshold, spanning the energy range required for calculations of the thermonuclear 33S(p, γ)34Cl rate in classical nova explosions. We have determined a new 33S(p, γ)34Cl rate using a Monte Carlo method and have performed new hydrodynamic nova simulations to determine the impact on nova nucleosynthesis of remaining nuclear physics uncertainties in the reaction rate. We find that these uncertainties lead to afactor of ≤5variation in the 33S(p, γ)34Cl rate over typical nova peak temperatures, and variation in the ejected nova yields of S–Ca isotopes by ≤20%. In particular, the predicted 32S/33S ratio is 110–130 for the nova model considered, compared to 110–440 with previous rate uncertainties. As recent type II supernova models predict ratios of 130–200, the 32S/33S ratio may be used to distinguish between grains of nova and supernova origin.

Manifestly T-duality covariant worldsheet string models can be constructed by doubling the coordinate fields. We describe the underlying gauge symmetry of a recently proposed Lorentz invariant doubled worldsheet theory that makes half of the worldsheet degrees of freedom redundant. By shifting the Lagrange multiplier, that enforces the gauge fixing condition, the worldsheet action can be cast into various guises. We investigate the renormalization of this theory using a non-linear background/quantum split by employing a normal coordinate expansion adapted to the gauge-fixed theory. The propagator of the doubled coordinates contains a projection operator encoding that half of them do not propagate. We determine the doubled target space equations of motion by requiring one-loop Weyl invariance. Some of them are generalizations of the conventional sigma model beta-functions, while others seem to be novel to the doubled theory: in particular, a dilaton equation seems related to the strong constraint of double field theory. However, the other target space field equations are not identical to those of double field theory.

In this Letter, we first demonstrate the existence of renormalization group invariant relations among the top, bottom Yukawa and the gauge colour couplings in the minimal supersymmetric SM. Based on this observation and assuming furthermore the existence of a renormalization group invariant relation among the trilinear couplings in the superpotential and the soft supersymmetry breaking sector, we obtain predictions for the Higgs masses and the supersymmetric spectrum.

Cell division is an essential dynamic event in tissue remodeling during wound healing, cancer and embryogenesis. In collective migration, tensile stresses affect cell shape and polarity, hence, the orientation of the cell division axis is expected to depend on cellular flow patterns. Here, we study the degree of orientation of cell division axes in migrating and resting epithelial cell sheets. We use microstructured channels to create a defined scenario of directed cell invasion and compare this situation to resting but proliferating cell monolayers. In experiments, we find a strong alignment of the axis due to directed flow while resting sheets show very weak global order, but local flow gradients still correlate strongly with the cell division axis. We compare experimental results with a previously published mesoscopic particle based simulation model. Most of the observed effects are reproduced by the simulations.

We give a construction for a general class of vertices in superstring field theory which include integration over bosonic moduli as well as the required picture changing insertions. We apply this procedure to find a covariant action for the NS-NS sector of Type II closed superstring field theory.

The transition from the near-single to the multi-cycle regime in non-sequential double ionization of argon is investigated experimentally. Argon atoms are exposed to intense laser pulses with a center wavelength around 790 nm and the momenta of electrons and ions generated in the double ionization process are measured in coincidence using a reaction microscope. The duration of the near transform-limited pulses is varied from 4 to 30 fs. We observe an abrupt collapse of the cross-shaped two-electron momentum distribution 17 in the few-cycle regime. The transition to longer pulses is further accompanied by a strong increase in the fraction of anti-correlated to correlated electrons.

High harmonic generation on solid and gaseous targets has been proven to be a powerful platform for the generation of attosecond pulses. Here we demonstrate a novel technique for the XUV generation on a smooth liquid surface target in vacuum, which circumvents the problem of low repetition rate and limited shot numbers associated with solid targets, while it maintains some of its merits. We employed atomically smooth, continuous liquid jets of water, aqueous salt solutions and ethanol that allow uninterrupted high harmonic generation due to the coherent wake emission mechanism for over 8 h. It has been found that the mechanism of plasma generation is very similar to that for smooth solid target surfaces. The vapor pressure around the liquid target in our setup has been found to be very low such that the presence of the gas phase around the liquid jet could be neglected.

In this paper, we construct non-trivial solutions to the 2D-dimensional field equations of Double Field Theory (DFT) by using a consistent Scherk-Schwarz ansatz. The ansatz identifies 2(D - d) internal directions with a twist U-N(M) which is directly connected to the covariant fluxes F-ABC. It exhibits 2(D - d) linear independent generalized Killing vectors K-I (J) and gives rise to a gauged supergravity in d dimensions. We analyze the covariant fluxes and the corresponding gauged supergravity with a Minkowski vacuum. We calculate fluctuations around such vacua and show how they gives rise to massive scalars field and vectors field with a non-abelian gauge algebra. Because DFT is a background independent theory, these fields should directly correspond the string excitations in the corresponding background. For (D − d) = 3 we perform a complete scan of all allowed covariant fluxes and find two different kinds of backgrounds: the single and the double elliptic case. The later is not T-dual to a geometric background and cannot be transformed to a geometric setting by a field redefinition either. While this background fulfills the strong constraint, it is still consistent with the Killing vectors depending on the coordinates and the winding coordinates, thereby giving a non-geometric patching. This background can therefore not be described in Supergravity or Generalized Geometry.

In this paper we show that the Germani-Kehagias model of Higgs inflation (or New Higgs Inflation), where the Higgs boson is kinetically non-minimally coupled to the Einstein tensor is in perfect compatibility with the latest Planck and BICEP2 data. Moreover, we show that the tension between the Planck and BICEP2 data can be relieved within the New Higgs inflation scenario by a negative running of the spectral index. Regarding the unitarity of the model, we argue that it is unitary throughout the evolution of the Universe. Weak couplings in the Higgs-Higgs and Higgs-graviton sectors are provided by a large background dependent cut-off scale during inflation. In the same regime, the W and Z gauge bosons acquire a very large mass, thus decouple. On the other hand, if they are also non-minimally coupled to the Higgs boson, their effective masses can be enormously reduced. In this case, the W and Z bosons are no longer decoupled. After inflation, the New Higgs model is well approximated by a quartic Galileon with a renormalizable potential. We argue that this can unitarily create the right conditions for inflation to eventually start.

Considering two dimensional gravity coupled to a CFT, we show that a semiclassical black hole can be described in terms of two Liouville theories matched at the horizon. The black hole exterior corresponds to a space-like while the interior to a time-like Liouville theory. This matching automatically implies that a semiclassical black hole has an infinite entropy. The path integral description of the time-like Liouville theory (the Black Hole interior) is studied and it is found that the correlation functions of the coupled CFT-gravity system are dominated by two (complex) saddle points, even in the semiclassical limit. We argue that this system can be interpreted as two interacting Bose-Einstein condensates constructed out of two degenerate quantum states. In AdS/CFT context, the same system is mapped into two interacting strings intersecting inside a three-dimensional BTZ black hole. (C) 2014 The Author

In quantum haplodynamics (QHD) the weak bosons, quarks, and leptons are bound states of fundamental constituents, denoted as haplons. The confinement scale of the associated gauge group SU(2)(h) is of the order of Lambda(h) approximate to 0.3 TeV. One scalar state has zero haplon number and is the resonance observed at the LHC. In addition, there exist new bound states of haplons with no counterpart in the SM, having a mass of the order of 0.5 TeV up to a few TeV. In particular, a neutral scalar state with haplon number 4 is stable and can provide the dark matter in the universe. The QHD, QCD, and QED couplings can unify at the Planck scale. If this scale changes slowly with cosmic time, all of the fundamental couplings, the masses of the nucleons and of the DM particles, including the cosmological term (or vacuum energy density), will evolve with time. This could explain the dark energy of the universe.