New Physics

A combination of experimental techniques, e.g. vector-MOKE magnetometry, Kerr microscopy and polarized neutron reflectometry, was applied to study the field induced evolution of the magnetization distribution over a periodic pattern of alternating exchange bias stripes. The lateral structure is imprinted into a continuous ferromagnetic/antiferromagnetic exchange-bias bi-layer via laterally selective exposure to He-ion irradiation in an applied field. This creates an alternating frozen-in interfacial exchange bias field competing with the external field in the course of the re-magnetization. It was found that in a magnetic field applied at an angle with respect to the exchange bias axis parallel to the stripes the re-magnetization process proceeds via a variety of different stages. They include coherent rotation of magnetization towards the exchange bias axis, precipitation of small random (ripple) domains, formation of a stripe-like alternation of the magnetization, and development of a state in which the magnetization forms large hyper-domains comprising a number of stripes. Each of those magnetic states is quantitatively characterized via the comprehensive analysis of data on specular and off-specular polarized neutron reflectivity. The results are discussed within a phenomenological model containing a few parameters which can readily be controlled by designing systems with a desired configuration of magnetic moments of micro-and nano-elements.

We have studied the magnetic structure that forms in a Fe/native Fe oxide multilayer by nuclear resonant scattering of synchrotron radiation and polarized neutron reflectometry. Magnetic field-dependent experiments revealed a non-collinear magnetic arrangement of the adjacent metallic layers which is mediated by an antiferromagnetically ordered oxide layer. Despite its antiferromagnetic (AFM) order, the oxide exhibits a small net magnetization attributed to the presence of metallic Fe within the AFM matrix that aligns parallel to the external field. The presence of a strong uniaxial anisotropy prevents the system from forming small magnetic domains in remanence. The canting angle between the two magnetic sublattices remains close to 90 • throughout the magnetization reversal on the hard axis. The results and the influence of the uniaxial anisotropy are discussed in the framework of the proximity magnetism model.

I give a brief review of the history of photon-photon physics and a survey of its potential at future electron-positron colliders. Exclusive hadron production processes in photon-photon and electron-photon collisions provide important tests of QCD at the amplitude level, particularly as measures of hadron distribution amplitudes. There are also important high energy γγ and eγ tests of quantum chromodynamics, including the production of jets in photon-photon collisions, deeply virtual Compton scattering on a photon target, and leading-twist single-spin asymmetries for a photon polarized normal to a production plane. Since photons couple directly to all fundamental fields carrying the electromagnetic current including leptons, quarks, W s, and supersymmetric particles, high energy γγ collisions will provide a comprehensive laboratory for Higgs production and exploring virtually every aspect of the Standard Model and its extensions. High energy back-scattered laser beams will thus greatly extend the range of physics of the International Linear Collider.

Initial-and final-state interactions from gluon-exchange, normally neglected in the parton model have a profound effect in QCD hard-scattering reactions, leading to leading-twist singlespin asymmetries, diffractive deep inelastic scattering, diffractive hard hadronic reactions, and nuclear shadowing and antishadowing-leading-twist physics not incorporated in the lightfront wavefunctions of the target computed in isolation. I also discuss the use of diffraction to materialize the Fock states of a hadronic projectile and test QCD color transparency. A remarkable feature of deep inelastic lepton-proton scattering at HERA is that approximately 10% events are diffractive 1,2 : the target proton remains intact, and there is a large rapidity gap between the proton and the other hadrons in the final state. These diffractive deep inelastic scattering (DDIS) events can be understood most simply from the perspective of the color-dipole model: the q q Fock state of the high-energy virtual photon diffractively dissociates into a diffractive dijet system. The exchange of multiple gluons between the color dipole of the q q and the quarks of the target proton neutralizes the color separation and leads to the diffractive final state. The same multiple gluon exchange also controls diffractive vector meson electroproduction at large photon virtuality. 3 This observation presents a paradox: if one chooses the conventional parton model frame where the photon light-front momentum is negative q+ = q 0 + q z < 0, the virtual photon interacts with a quark constituent with light-cone momentum fraction x = k + /p + = x bj . Furthermore, the gauge link associated with the struck quark (the Wilson line) becomes unity in light-cone gauge A + = 0. Thus the struck "current" quark apparently experiences no final-state interactions. Since the light-front wavefunctions ψ n (x i , k ⊥i ) of a stable hadron are real, it appears impossible to generate the required imaginary phase associated with pomeron exchange, let alone large rapidity gaps. This paradox was resolved by Paul Hoyer, Nils Marchal, Stephane Peigne, Francesco Sannino and myself. Consider the case where the virtual photon interacts with a strange quark-the ss pair is assumed to be produced in the target by gluon splitting. In the case of Feynman gauge, the struck s quark continues to interact in the final state via gluon exchange as described by the Wilson line. The final-state interactions occur at a light-cone time ∆τ 1/ν shortly after the virtual photon interacts with the struck quark. When one integrates over the nearly-on-shell intermediate state, the amplitude acquires an imaginary part. Thus the rescattering of the quark produces a separated color-singlet ss and an imaginary phase. In the case of the light-cone gauge A + = η •A = 0, one must also consider the final-state interactions of the (unstruck) s quark. The gluon propagator in light-cone gauge The momentum of the exchanged gluon k + is of O(1/ν); thus rescattering contributes at leading twist even in light-cone gauge. The net result is gauge invariant and is identical to the color dipole model calculation. The calculation of the rescattering effects on DIS in Feynman and light-cone gauge through three loops is given in detail for an Abelian model in the references. The result shows that the rescattering corrections reduce the magnitude of the DIS cross section in analogy to nuclear shadowing. A new understanding of the role of final-state interactions in deep inelastic scattering has thus emerged. The multiple scattering of the struck parton via instantaneous interactions in the target generates dominantly imaginary diffractive amplitudes, giving rise to an effective "hard pomeron" exchange. The presence of a rapidity gap between the target and diffractive system requires that the target remnant emerges in a color-singlet state; this is made possible

It is usually assumed -following the parton model -that the leading-twist structure functions measured in deep inelastic lepton-proton scattering are simply the probability distributions for finding quarks and gluons in the target nucleon. In fact, gluon exchange between the outgoing quarks and the target spectators effects the leading-twist structure functions in a profound way, leading to diffractive leptoproduction processes, shadowing and antishadowing of nuclear structure functions, and target spin asymmetries, physics not incorporated in the light-front wavefunctions of the target computed in isolation. In particular, final-state interactions from gluon exchange lead to single-spin asymmetries in semi-inclusive deep inelastic lepton-proton scattering which are not power-law suppressed in the Bjorken limit. The shadowing and antishadowing of nuclear structure functions in the Gribov-Glauber picture is due respectively to the destructive and constructive interference of amplitudes arising from the multiple-scattering of quarks in the nucleus. The effective quark-nucleon scattering amplitude includes Pomeron and Odderon contributions from multi-gluon exchange as well as Reggeon quark-exchange contributions. Part of the anomalous NuTeV result for sin 2 θ W could be due to the non-universality of nuclear antishadowing for charged and neutral currents. Detailed measurements of the nuclear dependence of individual quark structure functions are thus needed to establish the distinctive phenomenology of shadowing and antishadowing and to make the NuTeV results definitive. I also discuss diffraction dissociation as a tool for resolving hadron substructure Fock state by Fock state and for producing leading heavy quark systems.

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Though the predictions of the Standard Model (SM) are in excellent agreement with experiments there are still several theoretical problems associated with the Higgs sector of the SM, where it is widely believed that some "new physics" will take over at the TeV scale. One beyond the SM theory which resolves these problems is the Little Higgs (LH) model. In this work we have investigated the effects of the LH model on γγ → γγ scattering 1 .

The Heusler alloys Co 2 MnSi and NiMnSb are predicted to be 100% spin-polarized and are leading candidate materials for spin-injection and detection in hybrid spintronic devices. Co 2 MnSi is lattice matched with GaAs, whereas NiMnSb is strongly mismatched to GaAs. Here, we study the temperature and thickness dependence of the anomalous Hall (AH) effect in a series of textured, predominantly (001) oriented, sputter deposited Co 2 MnSi thin films on GaAs, and compare the behaviour to that of a molecular beam epitaxy (MBE) grown NiMnSb film on GaAs (001) with low antisite disorder. We show that the Co 2 MnSi films have temperature independent AH conductivity, even for the thinnest films with strongly temperature dependent saturation magnetization. We discuss whether a temperature insensitive AH conductivity necessarily indicates that the spinpolarization of charge carriers is also temperature independent.

This work presents a comprehensive theoretical-computational investigation of the positronelectron annihilation process, focusing on critical evaluation of the standard approximation that treats atomic electrons as free and at rest. We develop and validate corrections accounting for atomic binding effects, initial electron momentum, and electron density distribution in materials with different atomic numbers (Z) and electronic structures. Using a hybrid approach combining quantum scattering analytical methods with high-performance Fortran simulations, we quantify systematic deviations introduced by the simplified approximation, particularly for low-energy incident positrons (E+ < 1 MeV) and high-electron-density materials. Our implementation provides more accurate cross-sections, contributing to refined electromagnetic shower simulations with potential impacts on medical imaging (PET) and materials spectroscopy.

This paper presents the first complete modular–complex multiplication (CM) proof of the Gourevitch hypergeometric identity for 1 divided by pi squared, resolving a long-standing open conjecture in the Ramanujan–Sato family of series. The identity expresses a specific hypergeometric 5F4 series with parameters 1/2, 1/8, 3/8, 5/8, and 7/8 as a closed form equal to 56 times the square root of 7 divided by pi squared.

The proof follows a classical four-stage modular framework.
First, a tuned differential operator D = 15 + 2224θ + 1920θ(θ−1) is constructed to eliminate the non-modular component of the base 5F4 function.
Second, a quadratic pullback relation 49u² + (14−X)u + 1 = 0 links the hypergeometric argument to the Fricke-invariant Hauptmodul X(τ) for the modular curve X₀(7).
Third, a normalized prefactor, defined as (pi² / 60) multiplied by F(u(τ)) divided by K(k(τ))², is shown to be holomorphic and identically one on the genus-zero curve.
Finally, at the CM point τ = (−1 + √−7) / 2, the Chowla–Selberg formula expresses the eta-function in terms of Gamma products, giving the exact constant 56√7 / pi².

Every derivation is explicit and reproducible with high-precision SymPy and mpmath code, verified numerically to at least 120 digits.
This modular–CM method establishes a rigorous template for future proofs of Ramanujan–Sato type identities for 1 divided by pi to the power k, bridging symbolic mathematics, modular forms, and computational number theory.

📘 License

Creative Commons Attribution 4.0 International (CC BY 4.0)

🔑 Keywords

Ramanujan–Sato series; Gourevitch identity; modular forms; complex multiplication; hypergeometric functions; Chowla–Selberg formula; experimental mathematics; high-precision computation; eta and theta functions; modular parametrization.

The SuperKEKB accelerator complex is now being upgraded to bring the world highest luminosity (L=8x10 /cm/s). Hence, the KEKB injector linac is required to produce: electron: 20 mm mrad (7 GeV, 5 nC), positron: 10 mm mrad (4 GeV, 4 nC). To achieve this, the accelerator components have to be aligned within ± 0.1 mm (1 !). A beam position monitor (BPM) is essential instrumentation for beam-based alignment (BBA), and is required to be one magnitude better position resolution to get better alignment results. Since a current BPM readout system using oscilloscopes has ~50 μm position resolution, we decided to develop high precision BPM readout system with narrow bandpass filters. It handles two bunches with 96 ns interval and has a dynamic range between 0.1 nC (for photon factory) to 10 nC (positron primary). To achieve these criteria, we adopt semiconductor attenuators and optimized two-stage Bessel filters at 300 MHz center frequency to meet both time and frequency domain constraints. T...

This paper reports on a present status of a positron injector linac upgrade for SuperKEKB. A development status of a flux concentrator for positron focusing is shown. An influence of offset layout of the flux concentrator and the target on a positron yield is described. Positron capture by L-band and large aperture S-band accelerating structures are compared in a viewpoint of satellite bunch elimination. Beam optical design compatible to electrons and positrons of different beam energies is discussed.

We present a measurement of π + π -π + π -photonuclear production in ultra-peripheral Au-Au collisions at √ s NN = 200 GeV from the STAR experiment. The π + π -π + π -final states are observed at low transverse momentum and are accompanied by mutual nuclear excitation of the beam particles. The strong enhancement of the production cross section at low transverse momentum is consistent with coherent photoproduction. The π + π -π + π -invariant mass spectrum of the coherent events exhibits a broad peak around 1540 ± 40 MeV/c 2 with a width of 570 ± 60 MeV/c 2 , in agreement with the photoproduction data for the ρ 0 (1700). We do not observe a corresponding peak in the π + π -final state and measure an upper limit for the ratio of the branching fractions of the ρ 0 (1700) to π + π -and π + π -π + π -of 2.5 % at 90 % confidence level. The ratio of ρ 0 (1700) and ρ 0 (770) coherent production cross sections is measured to be 13.4 ± 0.8stat. ± 4.4syst.%.

The extended Bose-Hubbard model subjected to a disordered potential is predicted to display a rich phase diagram. In the case of uniform random disorder one finds two insulating quantum phases -the Mott-insulator and the Haldane insulator -in addition to a superfluid and a Bose glass phase. In the case of a quasiperiodic potential further phases are found, eg the incommensurate density wave, adiabatically connected to the Haldane insulator. For the case of weak random disorder we determine the phase boundaries using a perturbative bosonization approach. We then calculate the entanglement spectrum for both types of disorder, showing that it provides a good indication of the various phases.

X-ray flares, whose primary process we still miss, and other much weaker solar brightenings have their roots in magnetized regions. Until now, solar X-ray emission had actually been discarded as a potential axion signature, as it did not match two basic expectations of the solar axion model: a) an axion X-ray signal must appear exclusively near the disk centre, and b) its analog spectrum must peak at ~4-5 keV. On the contrary, we show here that they can appear in all longitudes and their intensity can peak at low energies. Due to Compton scattering off the (plasma) electrons, the outward propagation of X-rays from axions or the like converted near the Sun's surface can explain the observed low X-ray energy distribution and its non-directivity. Simulation points at the photosphere as the birth place of the presumed axion conversion, implying an axion rest mass m a ≈m γ ≈(1-2) • 10 -2 eV/c 2 . This result supports previous claims, whose strength scales with B 2 , typical for axions. At present, even optimistic parameter values cannot reproduce the measured X-ray intensities, i.e. either the solar axion source is not as anticipated or/and the inverse Primakoff-effect is not the main interaction mode. As a generic example we mention axion conversion in magnetic field gradients. The simulated photon spectrum peaking at low energies matches (qualitatively) reconstructed active and quiet Sun spectra. Interestingly, the shape of a reconstructed solar photon spectrum for the flaring Sun fits an energetically squeezed X-ray spectrum from converted axions. The recently observed hard solar X-ray emission from the quiet Sun could be alternatively due to massive and/or light axion involvement.

The origin of various celestial phenomena have remained mysterious for conventional astrophysics. Therefore, alternative solutions should be considered, taking into account the involvement of unstable dark-matter particle candidates, such as the celebrated axions or other as yet unforeseen axionlike particles. Their spontaneous and induced decay by the ubiquitous solar magnetic fields can be at the origin of persisting enigmatic X-ray emission, giving rise to a steady and a transient/local solar activity, respectively. The (coherent) conversion of photons into axion(-like) particles in intrinsic magnetic fields may modify the solar axion spectrum. The reversed process can be behind transient (solar) luminosity deficits in the visible. Then, the Sun might be also a strong source of ∼ eV-axions. The linear polarization of photons from converted axion(-like) particles inside magnetic fields is very relevant. Thus, enigmatic observations might be the as yet missing direct signature for axion(-like) particles in earth-bound detectors.

A few unexplained astrophysical observations could find a natural explanation by assuming the existence of electromagnetically decaying low-energy axions or other axion-like particles emitted from the Sun or other Sun-like stars. The decay photons would give rise to a 'self-illumination' of the Sun, providing the missing origin of the hot solar corona heating mechanism. Furthermore, in analogy with the terrestrial and other planetary atmospheres, the step-like temperature and density gradient in the transition region between the chromosphere and the corona, as yet not understood, can be naturally explained in terms of the absorption of these photons in this region of the solar atmosphere. We consider the observed soft-X-ray emission from the direction of the dark side of the Moon as a further signature of solar axion decays in flight, occurring between the Earth and the Moon. Surprisingly, later re-analyses of these X-rays tentatively consider their origin as being, against conventional reasoning, outside the Moon; their intensity is higher than the one expected from the interaction of the solar wind with the lunar surface by more than a factor of 10. With this scenario one could also explain the as yet missing origin of the diffuse (soft) X-ray background radiation. In all of these observations a temperature component of ∼ 10 6 K is present. Under the assumption of isotropic decay, combined solar observations provide evidence for axion(-like) particles in the sub-keV range with a mean decay length of ∼ 0.05 AU. To directly confirm this, we propose a search for two coincident photons below ∼ 400 eV, but the 'window of opportunity' is below a few keV.

The Circular Electron Positron Collider (CEPC) is a large international scientific facility proposed by the Chinese particle physics community to explore the Higgs boson and provide critical tests of the underlying fundamental physics principles of the Standard Model that might reveal new physics. The CEPC, to be hosted in China in a circular underground tunnel of approximately 100 km in circumference, is designed to operate as a Higgs factory producing electron-positron collisions with a center-of-mass energy of 240 GeV. The collider will also operate at around 91.2 GeV, as a Z factory, and at the WW production threshold (around 160 GeV). The CEPC will produce close to one trillion Z bosons, 100 million W bosons and over one million Higgs bosons. The vast amount of bottom quarks, charm quarks and tau-leptons produced in the decays of the Z bosons also makes the CEPC an effective B-factory and tau-charm factory. The CEPC will have two interaction points where two large detectors wil...

Abstract: The implication of the fourth-generation quarks in the B-&gt; K^* l^+ l^-(l= mu, tau) decays, when K^* meson is longitudinally or transversely polarized, is presented. In this context, the dependence of the branching ratio with polarized K^* and the helicity fractions ...

A comparative study of the exclusive rare B c → D * s ℓ + ℓ -(ℓ = µ, τ ) decays has been made in the minimal supersymmetric models (MSSM) and the SUSY SO(10) GUT models. In this context, various physical observables such as branching ratios (BR), forward-backward asymmetries (A F B ), lepton polarization asymmetries (P L,N,T ) and helicity fractions (f L,T ) of D * s meson by using the the QCD sum rules form factors have been investigated. It is found that the SUSY effects are characteristically prominent to that of the SM values for these observables. For instance, in SUSY I and SUSY II, the forward-backward asymmetry does not cross zero which is mainly due to the same sign of the C ef f 7 and C ef f 9 Wilson coefficients. Similarly in SUSY SO(10) GUT models due to the complex nature of the new Wilson coefficients -corresponding to the new operators arising due to the contribution of neutral Higgs bosons (NHBs) -the above mentioned observables are sizably affected. Therefore the analysis of said observables in charmed semileptonic B meson decays can put some stringent constraints on the parameter space of SUSY variants and can serve as a windowpane to look beyond the SM.

We study the implications for two-Higgs-doublet models of the recent announcement at the LHC giving a tantalizing hint for a Higgs boson of mass 125 GeV decaying into two photons. We require that the experimental result be within a factor of 2 of the theoretical standard model prediction, and analyze the type I and type II models as well as the lepton-specific and flipped models, subject to this requirement. It is assumed that there is no new physics other than two Higgs doublets. In all of the models, we display the allowed region of parameter space taking the recent LHC announcement at face value, and we analyze the W+W-, ZZ, (b) over barb, and tau(+)tau(-) expectations in these allowed regions. Throughout the entire range of parameter space allowed by the gamma gamma constraint, the numbers of events for Higgs decays into WW, ZZ, and b (b) over bar are not changed from the standard model by more than a factor of 2. In contrast, in the lepton-specific model, decays to tau(+)tau(-) are very sensitive across the entire gamma gamma-allowed region.

Flavour changing neutral currents are absent at tree level in the Standard Model (SM) and are highly suppressed at higher orders due the Glashow-Iliopoulos-Maiani mechanism. Hence, any evidence of such currents related to the top quark will definitely signal new physics beyond the SM. In this work we will discuss how an electron-positron collider can contribute to the field after the Large Hadron Collider (LHC) has collected at least 100 f b -1 of integrated luminosity operating at √ s = 14 T eV .

An interesting link between two very different physical aspects of quantum mechanics is revealed; these are the absence of third-order interference and Tsirelson's bound for the nonlocal correlations. Considering multiple-slit experiments - not only the traditional configuration with two slits, but also configurations with three and more slits - Sorkin detected that third-order (and higher-order) interference is not possible in quantum mechanics. The EPR experiments show that quantum mechanics involves nonlocal correlations which are demonstrated in a violation of the Bell or CHSH inequality, but are still limited by a bound discovered by Tsirelson. It now turns out that Tsirelson's bound holds in almost any other probabilistic theory provided that a reasonable calculus of conditional probability is included and third-order interference is ruled out.

A study of events with missing transverse energy and an energetic jet is performed using pp collision data at a centre-of-mass energy of 7 TeV. The data were collected by the CMS detector at the LHC, and correspond to an integrated luminosity of 36 pb -1 . An excess of these events over standard model contributions is a signature of new physics such as large extra dimensions and unparticles. The number of observed events is in good agreement with the prediction of the standard model, and significant extension of the current limits on parameters of new physics benchmark models is achieved.

A study of events with missing transverse energy and an energetic jet is performed using pp collision data at a centre-of-mass energy of 7 TeV. The data were collected by the CMS detector at the LHC, and correspond to an integrated luminosity of 36 pb -1 . An excess of these events over standard model contributions is a signature of new physics such as large extra dimensions and unparticles. The number of observed events is in good agreement with the prediction of the standard model, and significant extension of the current limits on parameters of new physics benchmark models is achieved.

We study the phase diagram of an SU(3)-symmetric mixture of threecomponent ultracold fermions with attractive interactions in an optical lattice, including the additional effect on the mixture of an effective three-body constraint induced by three-body losses. We address the properties of the system in D ≥ 2 by using dynamical mean-field theory and variational Monte Carlo techniques. The phase diagram of the model shows a strong interplay between magnetism and superfluidity. In the absence of the three-body constraint (no losses), the system undergoes a phase transition from a color superfluid phase to a trionic phase, which shows additional particle density modulations at half-filling. Away from the particle-hole symmetric point the color superfluid phase is always spontaneously magnetized, leading to the formation of different color superfluid domains in systems where the total number of particles of each species is conserved. This can be seen as the SU(3) symmetric realization of a more general tendency to phase-separation in three-component Fermi mixtures. The three-body constraint strongly disfavors the trionic phase, stabilizing a (fully magnetized) color superfluid also at strong coupling. With increasing temperature we observe a transition to a non-magnetized SU (3) Fermi liquid phase.

A literature review has indicated that the remote control, the main physical artifact of interaction with the television system, in its current form is not adequate to the interaction between users and applications of Interactive Digital Television (iDTV), especially in a scenario of diverse user profiles as found in Brazil. This paper describes participatory practices carried out with the intention of defining a new physical artifact of interaction for iDTV. Based on the results of these participatory practices and previous research results, we provide a definition of an artifact that can be adapted to diverse contexts of use.

A laser spectroscopic method for sensitive electric field measurements using krypton has been developed. The Stark effect of high Rydberg states of the krypton autoionizing series can be measured by a technique called fluorescence dip spectroscopy (FDS) with high spatial and temporal resolution. Calibration measurements have been performed in a reference cell with known electric field and they agree very well with numerical solutions of Schrödinger's equation for jl-coupled states. The application of this method has been demonstrated in the sheath region of a capacitively coupled radiofrequency (RF) discharge. The laser spectroscopic method allows us to add krypton as a small admixture to various low temperature plasmas.

The dynamics of itinerant electrons in topological insulator (TI) thin films is investigated using a multi-band decomposition approach. We show that the electron trajectory in the 2D film is anisotropic and confined within a characteristic region. Remarkably, the confinement and anisotropy of the electron trajectory are associated with the topological phase transition of the TI system, which can be controlled by tuning the film thickness and/or applying an in-plane magnetic field. Moreover, persistent electron wavepacket oscillation can be achieved in the TI thin film system at the phase transition point, which may assist in the experimental detection of the jitter motion (Zitterbewegung). The implications of the microscopic picture of electron motion in explaining other transport-related effects, e.g., electron-mediated RKKY coupling in the TI thin film system, are also discussed.

Physics dares to describe Nature from elementary particles all the way up to cosmological objects like cluster of galaxies and black holes. Although a unified description for all this spectrum of events is desirable, an one-theory-fits-all would be highly impractical. To not get lost in unnecessary details, effective descriptions are mandatory. Here we analyze what are the dynamics that may emerge from a fully quantum description when one does not have access to all the degrees of freedom of a system. More concretely, we describe the properties of the dynamics that arise from Quantum Mechanics if one has only access to a coarse grained description of the system. We obtain that the effective channels are not necessarily of Kraus form, due to correlations between accessible and non-accessible degrees of freedom, and that the distance between two effective states may increase under the action of the effective channel. We expect our framework to be useful for addressing questions such a...

We discuss 2f production at LC energies (f = t). This type of reaction has a big event number and may give interesting hints to the existence and perhaps to details of New Physics like susy, LQ, Z&#x27;, etc. For any search the radiative corrections have to be controlled carefully. ...

We report a new class of self-similar solutions for plasma expanding into vacuum that allows for quasi-monoenergetic ion spectra. A simple analytical model takes into account externally controlled time-dependent temperature of the hot electrons. When the laser temporal profile is tailored properly, the quasi-neutral self-similar expansion of the plasma results in ion concentration in the phase-space at a particular velocity thus producing a quasi-monoenergetic spectrum. We prove this analytical prediction using a 1D partice-in-cell (PIC) simulation where the time-dependent plasma temperature is controlled by two laser pulses shot at a foil with a suitable time delay between them.

We study the effects of relaxational dynamics on congestion pressure in scale free networks by analyzing the properties of the corresponding gradient networks [1]. Using the Family model from surface-growth physics as single-step load-balancing dynamics, we show that the congestion pressure considerably drops on scale-free networks when compared with the same dynamics on random graphs. This is due to a structural transition of the corresponding gradient network clusters, which self-organize such as to reduce the congestion pressure. This reduction is enhanced when lowering the value of the connectivity exponent λ towards 2.

Quantum error-correcting code for higher dimensional systems can, in general, be directly constructed from the codes for qubit systems. What remains unknown is whether there exist efficient code design techniques for higher dimensional systems. In this paper, we propose a 7-qutrit errorcorrecting code for the ternary quantum system and show that this design formulation has no equivalence in qubit systems. This code is optimum in the number of qutrits required to correct a single error while maintaining the CSS structure. This degenerate CSS code can (i) correct up to seven simultaneous phase errors and a single bit error, (ii) correct two simultaneous bit errors on pre-defined pairs of qutrits on eighteen out of twenty-one possible pairs, and (iii) in terms of the cost of implementation, the depth of the circuit of this code is only two more than that of the ternary Steane code. Our proposed code shows that it is possible to design better codes explicitly for ternary quantum systems instead of simply carrying over codes from binary quantum systems.

Multi-valued quantum systems can store more information than binary ones for a given number of quantum states. For reliable operation of multi-valued quantum systems, error correction is mandated. In this paper, we propose a 5qutrit quantum error correcting code and provide its stabilizer formulation. Since 5 qutrits are necessary to correct a single error, our proposed code is optimal in the number of qutrits. We prove that the error model considered in this paper spans the entire (3 × 3) operator space. Therefore, our proposed code can correct any single error on the codeword. This code outperforms the previous 9-qutrit code in (i) the number of qutrits required for encoding, (ii) our code can correct any arbitrary (3 × 3) error, (ii) our code can readily correct bit errors in a single step as opposed to the two-step correction used previously, and (iii) phase error correction does not require correcting individual subspaces.

Quantum error-correcting code for higher dimensional systems can, in general, be directly constructed from the codes for qubit systems. What remains unknown is whether there exist efficient code design techniques for higher dimensional systems. In this paper, we propose a 7-qutrit error-correcting code for the ternary quantum system and show that this design formulation has no equivalence in qubit systems. This code is optimum in the number of qutrits required to correct a single error while maintaining the CSS structure. This degenerate CSS code can (i) correct up to seven simultaneous phase errors and a single bit error, (ii) correct two simultaneous bit errors on pre-defined pairs of qutrits on eighteen out of twenty-one possible pairs, and (iii) in terms of the cost of implementation, the depth of the circuit of this code is only two more than that of the ternary Steane code. Our proposed code shows that it is possible to design better codes explicitly for ternary quantum system...

We study the asymptotic response of polar ordered active fluids ("flocks") to small external aligning fields h. The longitudinal susceptibility χ diverges, in the thermodynamic limit, like h -ν as h → 0. In finite systems of linear size L, χ saturates to a value ∼ L γ . The universal exponents ν and γ depend only on the spatial dimensionality d, and are related to the dynamical exponent z and the "roughness exponent" α characterizing the unperturbed flock dynamics. Using a well supported conjecture for the values of these two exponents, we obtain ν = 2/3, γ = 4/5 in d = 2 and ν = 1/4, γ = 2/5 in d = 3. These values are confirmed by our simulations.

Weber blockade in superconducting nanowires 1 TYLER MORGAN-WALL, BENJAMIN LEITH, NIKOLAUS HARTMAN, ATIKUR RAHMAN, NINA MARKOVIC, Johns Hopkins University -Vortices in superconductors are topological excitations that carry quantized magnetic flux and can be viewed as basic degrees of freedom that describe the low-energy states of the system. Here we show that a short superconducting nanowire can behave as a quantum dot for vortices. In the range of magnetic fields in which vortices can enter the nanowire in a single row, we find regular oscillations of the critical current as a function of magnetic field, with each oscillation corresponding to the addition of a single vortex to the nanowire. A charge-vortex dual of the Coulomb-blockaded quantum dot for electrons, the nanowire shows diamond-shaped regions of zero resistance as a function of current and magnetic field, in which the number of vortices is fixed. Besides demonstrating that macroscopic objects such as vortices can behave as fundamental particles, the fine control over critical currents and vortex configurations may prove useful for quantum devices that employ superconducting circuits.

We establish the potential existence of natural relations between the Cabibbo angle and the quark mass ratios, in a Standard Model with one Higgs doublet and two quark generations. The argument is based on the calculation of the divergent one-loop radiative corrections to the quark mass matrices.

We establish the existence of one-loop finite relations between the Cabibbo angle and the quark mass ratios, in the Standard Model with one Higgs doublet and two quark generations. Assuming a simple quark-lepton universality, we use the recent SNO results to predict the two-flavour mass spectrum of the neutrinos.

One of the most important developments in Monte Carlo simulation of collider events for the LHC has been the arrival of schemes and codes for matching of parton showers to matrix elements calculated at next-to-leading order in the QCD coupling. The POWHEG scheme, and particularly its implementation in the POWHEG-BOX code, has attracted most attention due to ease of use and effective portability between parton shower algorithms. But formal accuracy to NLO does not guarantee predictivity, and the beyond-fixed-order corrections associated with the shower may be large. Further, there are open questions over which is the &quot;best&quot; variant of the POWHEG matching procedure to use, and how to evaluate systematic uncertainties due to the degrees of freedom in the scheme. In this paper we empirically explore the scheme variations allowed in Pythia8 matching to POWHEG-BOX dijet events, demonstrating the effects of both discrete and continuous freedoms in emission vetoing details for bot...

The ability of the upgraded Arecibo 305-m telescope to produce quasiinstantaneous" radio continuum spectra covering over a decade of frequency has been investigated, the study being undertaken as an Arecibo Observatory 2 summer-student observing project. Within the limits of early post-upgrade instrumentation and telescope performance, it was found to be relatively easy for inexperienced observers to obtain the measurements needed to achieve the above objective. Good-quality spectra were produced for three quasars J1609+266, J2115+295 and J2203+317 which exhibited mutually di erent spectral shapes. The planetary nebula, G064.7+05.0, was also included in the target list. This is shown to be optically thick at 1.4 GHz, while only an upper limit to its ux density could be determined at 430 MHz.

We propose a quantum optomechanical method to probe the potential existence of dark matter particles possessing an infinitesimal electric charge, known as milli-charged particles (mCPs), when bound to ordinary matter. In our setup, a charged fused silica nanosphere (NS) is optically levitated within a Fabry-Perot cavity and subjected to an additional electrostatic field produced by a charged metallic ring. If mCPs exist and are embedded in the NS as relics of early Universe matter, their presence would generate a tiny but measurable deviation from a purely thermal output spectrum. Specifically, the output light from the cavity would exhibit quadrature squeezing even at room temperature, and the NS center-of-mass motion could become entangled with the optical field. These quantum effects are absent when there are no residual infinitesimal charges in the NS. We provide a theoretical framework for this proposal, including the system Hamiltonian and linearized quantum Langevin dynamics, and show how measurements of squeezing and entanglement in the cavity output can reveal the presence of bound mCPs.

We consider single photon realization of generalized N -qubit perfect W-states which are suitable for perfect teleportation and superdense coding. We propose schemes to generate generalized Nmode single photon perfect W-states and derive entanglement conditions which for single photon states require finding fidelity with generalized N -mode single photon perfect W-states and hence more suitable to detect the genuine entanglement of generalized perfect W-states. Based on the evolution of single photon wavefunction in scalable integrated photonic lattices, we present schemes for the preparation of generalized N -mode single photon perfect W-states at desired propagation distance. The integrated waveguide structures can precisely be fabricated, offer low photon propagation losses and can be integrated on a chip. We consider both planar and ring type waveguide structures for state generation. We derive set of generalized entanglement conditions using the sum uncertainty relations of generalized su(2) algebra operators. We show that any given genuinely entangled N -mode single photon state is a squeezed state of a specific su(2) algebra operator and can be expressed as superposition of a pair of orthonormal generalized N -mode single photon perfect W-states which are eigenstates of that specific su(2) algebra operator. Within the single photon subspace, the eigendecomposition of su(2) algebra operators reduces the generalized entanglement condition to a simplified single photon separability condition. In order to verify the entanglement of given genuinely entangled N -mode single photon state using this condition one has to find the difference between the state fidelities with suitably chosen pair of orthonormal generalized N -mode single photon perfect W-states. Finally, we propose an experimental scheme to verify the entanglement using the proposed conditions. This scheme uses a photonic circuit that consists of directional couplers, and phase shifters and the same photonic circuit can also be used to generate generalized N -mode single photon perfect W-states. Our results show that optical waveguide structures are ideal platforms for generation and entanglement verification of large N -mode single photon entangled states which could find novel applications in quantum information science.