Vacuum Value Research Articles

Operator description for thermal quantum field theories on an arbitrary path in the real time formalism

We develop an operator description, much like thermofield dynamics, for quantum field theories on a real time path with an arbitrary parameter $\sigma\,(0\leq\sigma\leq\beta)$. We point out new features which arise when $\sigma\neq \frac{\beta}{2}$ in that the Hilbert space develops a natural, modified inner product different from the standard Dirac inner product. We construct the Bogoliubov transformation which connects the doubled vacuum state at zero temperature to the thermal vacuum in this case. We obtain the thermal Green's function (propagator) for the real massive Klein-Gordon theory as an expectation value in this thermal vacuum (with a modified inner product). The factorization of the thermal Green's function follows from this analysis. We also discuss, in the main text as well as in two appendices, various other interesting features which arise in such a description.

Effects of an extended c-phase on vacuum conditions in the milking cluster

The objective of this study was to examine how a prolonged closing phase in the pulsation chamber cycle would affect vacuum conditions on the teat and liner movement. Wrong vacuum conditions and liner movements, controlled by pulsators, could cause discomfort on the teats and have negative effects on udder health. Therefore, 18 focal dairy cows were randomly subjected to two types of pulsation chamber cycles (treatments A and B) for 12 milkings in a low-line 2 × 3 auto tandem milking parlour. The treatments differed in the duration of closing and closed phases (c- and d-phases, respectively). In treatment A, the c-phase was 70 ms and the d-phase was 330 ms, whereas in treatment B, the c-phase lasted 130 ms and the d-phase 270 ms. Using a vacuum measuring device, measurement series with 5 s intervals were conducted during three phases of the milking process: the plateau phase, the decreasing phase, and the over-milking phase. Differences between the treatments were detected in the total pressure per cycle and maximum vacuum on the teat-end. Treatment B showed on average a 1 kPa s lower total pressure per cycle than treatment A, whereas values of maximum vacuum at the teat-end were on average 0.2 kPa higher in Treatment B than A. Further, differences could be detected between the three phases during the milking proceedings, showing that the observed parameters were related to the milk flow rate. The results indicate that treatment B might be gentler and more comfortable for dairy cows, which will be established next.

Клинико-рентгенологическая оценка эффективности лечения апикального периодонтита с применением авторской методики вакуумно-струйной ирригации корневых каналов

A device and techniques for vacuum-bolus irrigation of root canals are developed on the basis of the analysis of existing methods of medical treatment of root canals in endodontic treatment. A comparative assessment of the impact of different variables of vacuum on the degree of cleaning of the root canal model was carried out in an invitro experiment and the optimal values of vacuum and exposure time were pointed out. In the clinical part of the study 52 patients aged from 25 to 44 years with a diagnosis of apical periodontitis were treated and dynamically monitored during one year (the author`s vacuum-bolus technique was applied to 32 patients of the main study group in the course of endodontic irrigation of root canals; while 20 patients of the control group experienced a standard irrigation method with the use of endodontic syringe in the course of endodontic treatment). Criteria of the modified periapical index (PAI) were used to assess the efficacy of treatment. It was found that after 12 months, 90,5 % of patients of the main study group had no signs of demineralization of bone tissue, the orientation of bone trabeculae of cancellous bone and cortical plate were recovering. Thus, the vacuum-boluc irrigation of root canals can help us improve the efficiency of treatment of destructive forms of apical periodontitis.

Few layer graphene synthesis via SiC decomposition at low temperature and low vacuum

Based on the large-scale availability and good electrical properties, the epitaxial graphene (EG) on SiC exhibits a big potential for future electronic devices. However, it is still necessary to work continuously on lowering the formation temperature and vacuum values of EG while improving the quality and increasing the lateral size to fabricate high-performance electronic devices at reduced processing costs. In this study, we investigated the effect of the presence of Mo plate and hydrogen atmosphere as well as the vacuum annealing durations on SiC decomposition. Our studies showed that the graphene layers can be produced at lower annealing temperatures (1200 °C) and vacuum values (10−4 Torr) in the presence of Mo plate and hydrogen. For high quality continuous graphene formation, Mo plate should be in contact with SiC. If there is a gap between Mo and SiC, non-wetting oxide droplets on few layer graphene (FLG) are recorded. Moreover, it is found that the morphology of these islands can be controlled by changing the annealing time and atmosphere conditions, and applying external disturbances such as vibration.

Phenomenological neutron star equations of state

We discuss the 3-window modeling of cold, dense QCD matter equations of state at density relevant to neutron star properties. At low baryon density, n_B < ~ 2n_s (n_s: nuclear saturation density), we utilize purely hadronic equations of state that are constrained by empirical observations at density n_B ~ n_s and neutron star radii. At high density, n_B > ~ 5n_s, we use the percolated quark matter equations of state which must be very stiff to pass the two-solar mass constraints. The intermediate domain at 2 < n_B/n_s < 5 is described as neither purely hadronic nor percolated quark matter, and the equations of state are inferred by interpolating hadronic and percolated quark matter equations of state. Possible forms of the interpolation are severely restricted by the condition on the (square of) speed of sound, 0 < c_s^2 < 1. The characteristics of the 3-window equation of state are compared with those of conventional hybrid and self-bound quark matters. Using a schematic quark model for the percolated domain, it is argued that the two-solar mass constraint requires the model parameters to be as large as their vacuum values, indicating that the gluon dynamics remains strongly non-perturbative to n_B ~ 10n_s. The hyperon puzzle is also briefly discussed in light of quark descriptions.

Mesonic Decay of Charm Hypernuclei Λc+

$\Lambda^+_c$ hypernuclei are expected to have binding energies and other properties similar to those of strange hypernuclei in view of the similarity between the quark structures of the strange and charmed hyperons, namely $\Lambda(uds)$ and $\Lambda^+_c (udc)$. One striking difference however occurs in their mesonic decays, as there is almost no Pauli blocking in the nucleonic decay of a charm hypernucleus because the final-state nucleons leave the nucleus at high energies. The nuclear medium nevertheless affects the mesonic decays of charm hypernucleus because the nuclear mean fields modify the masses of the charm hyperon. In the present communication we present results of a first investigation of the effects of finite baryon density on different weak mesonic decay channels of the $\Lambda^+_c$ baryon. We found a non-negligible reduction of the decay widths as compared to their vacuum values.

Hierarchi problem

The way to solve the hierarchy problem based on multidimensional gravity is discussed. Various metrics of deformed extra space are produced at the Planck scale. It is shown that the Higgs vacuum value depends on a metric of extra space and hence their different numerical values are realized in various universes. An interval of the Higgs vacuum values is proved include zero value. Our universe belongs to a set of universes the vacuum values of which are close to zero

Combing gravitational hair in 2 + 1 dimensions

The gravitational Gauss law requires any addition of energy to be accompanied by the addition of gravitational flux. The possible configurations of this flux for a given source may be called gravitational hair, and several recent works discuss gravitational observables (‘gravitational Wilson lines’) which create this hair in highly collimated ‘combed’ configurations. We construct and analyze time-symmetric classical solutions of 2 + 1 Einstein–Hilbert gravity such as might be created by smeared versions of such operators. We focus on the AdS3 case, where this hair is characterized by the profile of the boundary stress tensor; the desired solutions are those where the boundary stress tensor at initial time t = 0 agrees precisely with its vacuum value outside an angular interval . At linear order in source strength the energy is independent of the combing parameter α, but nonlinearities cause the full energy to diverge as . In general, solutions with combed gravitational flux also suffer from what we call displacement from their naive location. For weak sources and large α one may set the displacement to zero by further increasing the energy, though for strong sources and small α we find no preferred notion of a zero-displacement solution. In the latter case we conclude that naively expected gravitational Wilson lines do not exist. In the zero-displacement case, taking the AdS scale ℓ to infinity gives finite-energy flux-directed solutions that may be called asymptotically flat.

A Model-Independent Discussion of Quark Number Density and Quark Condensate at Zero Temperature and Finite Quark Chemical Potential**Supported by the National Natural Science Foundation of China under Grant Nos 11275097, 11475085, 11105122, and 11535005, and the Jiangsu Planned Projects for Postdoctoral Research Funds under Grant No 1402006C.

Generally speaking, the quark propagator is dependent on the quark chemical potential in the dense quantum chromodynamics (QCD). By means of the generating functional method, we prove that the quark propagator actually depends on p4 + iμ from the first principle of QCD. The relation between quark number density and quark condensate is discussed by analyzing their singularities. It is concluded that the quark number density has some singularities at certain μ when T = 0, and the variations of the quark number density as well as the quark condensate are located at the same point. In other words, at a certain μ the quark number density turns to nonzero, while the quark condensate begins to decrease from its vacuum value.

Positronium contact density in ferrocene

In a medium where positronium (Ps) is formed, a lowering of the electron density at the positron position (contact density) with respect to a vacuum is generally observed. The effect is usually attributed to the interaction with the medium, which induces Ps polarization. The contact density reduction, explainable in polar media due to Debye forces, can be expected also in non-polar media, where London forces are present. To investigate this subject we measured the Ps contact density in ferrocene, an organometallic compound whose molecule does not have an intrinsic dipole moment; therefore, only induced dipole-induced dipole interactions may be present. Contact density was obtained by means of two different experimental techniques. A lowering by 23% with respect to vacuum value was observed, which allowed us a simple estimation of the order of magnitude of the effective microscopic electric field mimicking the Ps-ferrocene interaction.

Neutrino masses, theμ-term, andPSL2(7)

Using an $SO(10)$-inspired form for the Dirac neutrino mass, we map the neutrino data to right-handed neutrino Majorana mass-matrix, $\mathcal M$, and investigate a special form with \emph{seesaw} tribimaximal mixing; it predicts a normal hierarchy, and the values of the light neutrino masses. It may be generated by mapping the top quark hierarchy onto the vacuum values of familon fields transforming under the family group $\mathcal{ PSL}_2(7)$. We next investigate the hypothesis that these familons play a dual role, generating a hierarchy in the supersymmetric $\mathbf \mu$-mass matrix of Higgses carrying family quantum numbers. A special $\mathcal{ PSL}_2(7)$ invariant coupling produces a $\mu$-matrix with a hierarchy of thirteen orders of magnitude. Only one Higgs field (per hypercharge sector) is light enough (with a $\mu$-mass $\sim 10-100$ GeV) to be destabilized by SUSY soft breaking at the TeV scale, and upon spontaneous symmetry breaking, gives \emph{tree-level} masses for the heaviest family.

Generating sequences of phonon wave packets by optical excitation of a quantum dot

Phonons can play an active role in controlling solid state systems or in the transport of energy and information. Thus, it is vital to understand generation processes and properties of phonons. By optical excitation of a semiconductor quantum dot, a sequence of phonon wave packets can be created. In this paper we focus on the fluctuation properties of lattice displacement and momentum of these phonon wave packets. For detuned excitation the fluctuations may fall below their respective vacuum values and squeezing occurs.

Cosmic inflation constrains scalar dark matter

In a theory containing scalar fields, a generic consequence is a formation of scalar condensates during cosmic inflation. The displacement of scalar fields out from their vacuum values sets specific initial conditions for post-inflationary dynamics and may lead to significant observational ramifications. In this work, we investigate how these initial conditions affect the generation of dark matter in the class of portal scenarios where the standard model fields feel new physics only through Higgs-mediated couplings. As a representative example, we will consider a Z2 symmetric scalar singlet s coupled to Higgs via λΦ†Φs2. This simple extension has interesting consequences as the singlet constitutes a dark matter candidate originating from non-thermal production of singlet particles out from a singlet condensate, leading to a novel interplay between inflationary dynamics and dark matter properties.

On classical solutions of 4d supersymmetric higher spin theory

We present a simple construction of solutions to the supersymmetric higher spin theory based on solutions to bosonic theories. We illustrate this for the case of the Didenko-Vasiliev solution in arXiv:0906.3898, for which we have found a striking simplification where the higher-spin connection takes the vacuum value. Studying these solutions further, we check under which conditions they preserve some supersymmetry in the bulk, and when they are compatible with the boundary conditions conjectured to be dual to certain 3d SUSY Chern-Simons-matter theories. We perform the analysis for a variety of theories with $\mathcal{N}$ = 2, $\mathcal{N}$ = 3, $\mathcal{N}$ = 4 and $\mathcal{N}$ = 6 and find a rich spectrum of $1/4$, $1/3$ and $1/2$-BPS solutions.

Uncertainty in length conversion due to change of sensitivity coefficients of refractive index

A value of length measured in air should be converted to the value in vacuum for the purpose of comparison. The typical values of the sensitivity coefficients for a particular wavelength (e.g. 632.99nm) under standard environmental conditions are widely available. Because all measurements are not performed under standard environmental conditions and the sensitivity coefficient is affected by atmospheric pressure, temperature, and humidity, one question arises naturally: how does a measurement change with environmental conditions? This study investigates the uncertainty in length conversion due to the change of sensitivity coefficients of refractive index. We also clarify that there is no significant difference in conversion uncertainties via sensitivity coefficients of phase and group refractive indexes.

Thermal Properties of Light Tensor Mesons via QCD Sum Rules

The thermal properties off2(1270),a2(1320), andK2*(1430) light tensor mesons are investigated in the framework of QCD sum rules at finite temperature. In particular, the masses and decay constants of the light tensor mesons are calculated taking into account the new operators appearing at finite temperature. The numerical results show that, at the point at which the temperature-dependent continuum threshold vanishes, the decay constants decrease with amount of (70–85)% compared to their vacuum values, while the masses diminish about (60–72)% depending on the kinds of the mesons under consideration. The results obtained at zero temperature are in good consistency with the experimental data as well as the existing theoretical predictions.

DSMesons in Asymmetric Hot and Dense Hadronic Matter

The in-medium properties ofDSmesons are investigated within the framework of an effective hadronic model, which is a generalization of a chiralSU(3)model, toSU(4), in order to study the interactions of the charmed hadrons. In the present work, theDSmesons are observed to experience net attractive interactions in a dense hadronic medium, hence reducing the masses of theDS+andDS-mesons from the vacuum values. While this conclusion holds in both nuclear and hyperonic media, the magnitude of the mass drop is observed to intensify with the inclusion of strangeness in the medium. Additionally, in hyperonic medium, the mass degeneracy of theDSmesons is observed to be broken, due to opposite signs of the Weinberg-Tomozawa interaction term in the Lagrangian density. Along with the magnitude of the mass drops, the mass splitting betweenDS+andDS-mesons is also observed to grow with an increase in baryonic density and strangeness content of the medium. However, all medium effects analyzed are found to be weakly dependent on isospin asymmetry and temperature. We discuss the possible implications emanating from this analysis, which are all expected to make a significant difference to observables in heavy ion collision experiments, especially the upcoming Compressed Baryonic Matter (CBM) experiment at the future Facility for Antiproton and Ion Research (FAIR), GSI, where matter at high baryonic densities is planned to be produced.

Study of superfluid 3He films with a micro-electro-mechanical device

A micro-electro-mechanical system (MEMS) device with a 1.25 μm gap between a movable plate and the substrate was immersed in superfluid 3He and cooled below 500 μK at 21.2 bar. Mechanical resonances of its shear motion were monitored on warming from the base temperature. Our preliminary results demonstrate increasing damping and decreasing resonance frequencies with temperature, consistent with a thermal damping model caused by thermal quasiparticles. The quality factor (Q) of the oscillator remains surprisingly low (Q ≈ 30) down to 0.2 T/Tc, about 4 orders of magnitude smaller than the value in vacuum at 4K. The average superfluid gap was determined to be significantly suppressed from the value in bulk at the corresponding pressure.

Thermal behaviors of light unflavored tensor mesons in the framework of QCD sum rule

In this paper, we investigated the sensitivity of the masses and decay constants of f2(1270) and a2(1320) tensor mesons to the temperature using OCD sum rule approach. In our calculations, we take into account new additional operators appearing in operator product expansion (OPE). At the end of numerical analyses we show that at deconfinement temperature the decay constants and masses decreased by 6% and 96% of their vacuum values, respectively. Our results on the masses and decay constants at zero temperature of the tensor mesons are consistent with the experimental data as well as the vacuum sum rules predictions.

Dense baryonic matter in conformally-compensated hidden local symmetry: Vector manifestation and chiral symmetry restoration

We find that, when the dilaton is implemented as a (pseudo-)Nambu-Goldstone boson using a conformal compensator or "conformon" in a hidden gauge symmetric Lagrangian written to $O(p^4)$ from which baryons arise as solitons, namely, skyrmions, the vector manifestation and chiral symmetry restoration at high density predicted in hidden local symmetry theory --- which is consistent with Brown-Rho scaling --- are lost or sent to infinite density. It is shown that they can be restored if in medium the behavior of the $\omega$ field is taken to deviate from that of the $\rho$ meson in such a way that the flavor $U(2)$ symmetry is strongly broken at increasing density. The hitherto unexposed crucial role of the $\omega$ meson in the structure of elementary baryon and multibaryon systems is uncovered in this work. In the state of half-skyrmions to which the skyrmions transform at a density $n_{1/2}^{} \gtrsim n_0^{}$ (where $n_0^{}$ is the normal nuclear matter density), characterized by the vanishing (space averaged) quark condensate but nonzero pion decay constant, the nucleon mass remains more or less constant at a value $\gtrsim$ 60 \% of the vacuum value indicating a large component of the nucleon mass that is not associated with the spontaneous breaking of chiral symmetry. We discuss its connection to the chiral-invariant mass $m_0^{}$ that figures in the parity-doublet baryon model.