Generic Vacuum Research Articles

Primordial magnetic non-Gaussianity with generic vacua and detection prospects in CMB spectral distortions

Primordial magnetic non-Gaussianity with generic vacua and detection prospects in CMB spectral distortions

Taming boundary condition changing operator anomalies with the tachyon vacuum

Motivated by the appearance of associativity anomalies in the context of superstring field theory, we give a generalized solution built from boundary condition changing operators which can be associated to a generic tachyon vacuum in the KBc subalgebra of the Okawa form. We articulate sufficient conditions on the choice of tachyon vacuum to ensure that ambiguous products do not appear in the equations of motion.

Compatibility of A_{4} flavour symmetric minimal extended seesaw with (3+1) neutrino data

Motivated by the recent resurrection of the evidence for an eV scale sterile neutrino from the MiniBooNE experiment, we revisit one of the most minimal seesaw model known as the minimal extended seesaw that gives rise to a 3+1 light neutrino mass matrix. We consider the presence of A_{4} flavour symmetry which plays a non-trivial role in generating the structure of the neutrino mass matrix. Considering a diagonal charged lepton mass matrix and generic vacuum alignments of A_{4} triplet flavons, we classify the resulting mass matrices based on their textures. Keeping aside the disallowed texture zeros based on earlier studies of 3+1 neutrino textures, we categorise the remaining ones based on texture zeros, mu –tau symmetry in the 3times 3 block and hybrid textures. After pointing out the origin of such 3+1 neutrino textures to A_{4} vacuum alignments, we use the latest 3+1 neutrino oscillation data and numerically analyse the texture zeros and mu –tau symmetric cases. We find that a few of them are allowed from each category predicting interesting correlations between neutrino parameters. We also find that all of these allowed cases prefer normal hierarchical pattern of light neutrino masses over inverted hierarchy.

Design and implementation of a non-magnetic cryogenic multi-conductor vacuum feedthrough

A common issue for experiments requiring very low magnetic fields on vacuum and cryogenic systems is how to deal with the control of magnetic properties of electrical contacts. We describe the design and implementation of a generic sixty-four pin non-magnetic cryogenic vacuum feedthrough capable of disconnecting contacts on both sides of the vacuum boundary.

Electroweak phase transitions in multi-Higgs models: the case of Trinification-inspired THDSM

The rich vacuum structure of multi-Higgs extensions of the Standard Model (SM) may have interesting cosmological implications for the electroweak phase transition (EWPT). As an important example of such class of models, we consider a particularly simple low-energy SM-like limit of a recently proposed Grand-Unified Trinification model with the scalar sector composed of two Higgs doublets and a complex singlet and with a global U(1) family symmetry. The fermion sector of this model is extended with a family of vector-like quarks which enhances CP violation. With the current study, we aim at exploring the generic vacuum structure and uncovering the features of the EWPT in this model relevant for cosmology. We show the existence of different phase transition patterns providing strong departure from thermal equilibrium. Most of these observations are not specific to the considered model and may generically be expected in other multi-Higgs extensions of the SM.

Fayet-Iliopoulos terms in supergravity without gauged R-symmetry

We construct a supergravity-Maxwell theory with a novel embedding of the Fayet-Iliopoulos D-term, leading to spontaneous supersymmetry breaking. The gauging of the R-symmetry is not required and a gravitino mass is allowed for a generic vacuum. When matter couplings are introduced, an uplift through a positive definite contribution to the scalar potential is obtained. We observe a notable similarity to the overline{D}3 uplift constructions and we give a natural description in terms of constrained multiplets.

A proposal for constraining initial vacuum by cosmic microwave background

We propose a theoretical framework that can possibly constrain the initial vacuum by observation of the cosmic microwave background (CMB). With a generic vacuum without any particular choice a priori, thereby keeping both the Bogolyubov coefficients in the analysis, we compute observable parameters from two- and three-point correlation functions. We are thus left with constraining four model parameters from the two complex Bogolyubov coefficients. We also demonstrate a method of finding out the constraint relations between the Bogolyubov coefficients using the theoretical normalization condition and observational data of power spectrum and bispectrum from CMB. Finally, we discuss the possible pros and cons of the analysis.

More about the instanton/soliton/kink correspondence

We demonstrate that all gauge instantons in a [Formula: see text] Yang–Mills theory, with generic topological vacuum charge [Formula: see text], correspond to soliton solutions and kink scalar fields in [Formula: see text] space-time.

Vacuum pumping options for application in solar thermochemical redox cycles – Assessment of mechanical-, jet- and thermochemical pumping systems

Solar powered two step thermochemical redox cycles are often investigated as a pathway to producing renewable fuels, via the splitting of water and carbon dioxide. These processes require a high temperature step for the reduction of the redox material. The reduction thermodynamics also critically depend on the oxygen partial pressure. In generic process assessments, purge gases and mechanical vacuum pumps have been considered for removing the released oxygen. Even though both alternatives are expected to have a significant impact on the overall process efficiency, little effort has been made so far in providing a detailed analysis of the implementation of the related components - especially in the case of vacuum pumps. In this study models are developed for assessing the energy requirements of mechanical vacuum pumps as well as for jet pumps. The models are validated and compared to data provided by manufacturers. In addition, a novel thermochemical pumping concept is introduced and a first thermodynamic assessment is presented. The energy demands of the different pump options are discussed in the context of the targeted application. By comparison with the energy stored in the produced fuel, limitations for the implementation of these systems can be identified. Furthermore, the costs for mechanical and jet pumps have been taken into account for the assessment. While mechanical pumps are energetically favored and could be reasonably applied for pressures down to 150Pa, jet pumps are the more economic option and can make direct use of waste heat, which should be vastly available in the process at the required temperature level. The concept of thermochemical pumps is energetically very interesting and might shift the limit of realistic operational pressures to lower values, especially when combined with conventional systems.

Geometric flows and Perelman’s thermodynamics for black ellipsoids in [formula omitted] and Einstein gravity theories

We study geometric relativistic flow and Ricci soliton equations which (for respective nonholonomic constraints and self-similarity conditions) are equivalent to the gravitational field equations of R2 gravity and/or to the Einstein equations with scalar field in general relativity, GR. Perelman’s functionals are generalized for modified gravity theories, MGTs, which allows to formulate an analogous statistical thermodynamics for geometric flows and Ricci solitons. There are constructed and analyzed generic off-diagonal black ellipsoid, black hole and solitonic exact solutions in MGTs and GR encoding geometric flow evolution scenarios and nonlinear parametric interactions. Such new classes of solutions in MGTs can be with polarized and/or running constants, nonholonomically deformed horizons and/or embedded self-consistently into solitonic backgrounds. They exist also in GR as generic off-diagonal vacuum configurations with effective cosmological constant and/or mimicking effective scalar field interactions. Finally, we compute Perelman’s energy and entropy for black ellipsoids and evolution solitons in R2 gravity.

Selective separation of CO2 and CH4 for biogas upgrading on zeolite NaKA and SAPO-56

Several commercial and potential adsorbents were investigated for the separation of CO2 from CH4, which is relevant for the upgrading of raw biogas. The main focus of the paper was on the working capacities and selectivities of the adsorbents for a generic vacuum swing adsorption (VSA) process. Zeolites 4A and 13X had good estimated CO2-over-CH4 selectivities and reasonably high working capacities for the removal of CO2. A variant of zeolite A – |Na12−xKx|-LTA (with 1.8⩽x⩽3.2), had at least the same working capacity as zeolite 4A but with a significantly improved selectivity. Hence, the environmentally important “CH4 slip” can be minimized with this |Na12−xKx|-LTA sorbent. If a high working capacity for CO2 removal is the most important characteristic for a VSA process, then silicoaluminum phosphate, specifically SAPO-56, appeared to be the best candidate among the studied sorbents. In addition, SAPO-56 had a substantially high estimated CO2-over-CH4 selectivity with a value between ∼20 and 30.

Confining strings in supersymmetric theories with Higgs branches

We study flux tubes (strings) on the Higgs branches in supersymmetric gauge theories. In generic vacua on the Higgs branches strings were shown to develop long-range "tails" associated with massless fields, a characteristic feature of the Higgs branch (the only exception is the vacuum at the base of the Higgs branch). A natural infrared regularization for the above tails is provided by a finite string length L. We perform a numerical study of these strings in generic vacua. We focus on the simplest example of strings in N=1 supersymmetric QED with the Fayet-Iliopoulos term. In particular, we examine the accuracy of a logarithmic approximation (proposed earlier by Evlampiev and Yung) for the tension of such string solutions. In the Evlampiev-Yung formula the dependence of tension on the string length is logarithmic and the dependence on the geodesic length from the base of the Higgs branch is quadratic. We observe a remarkable agreement of our numerical results for the string tension with the Evlampiev-Yung analytic expression.

Modified dynamical supergravity breaking and off-diagonal super-Higgs effects

We argue that generic off-diagonal vacuum and nonvacuum solutions for Einstein manifolds mimic physical effects in modified gravity theories (MGTs) and encode certain models of the , Hořava type with dynamical Lorentz symmetry breaking, induced effective mass for the graviton, etc. Our main goal is to investigate the dynamical breaking of local supersymmetry determined by off-diagonal solutions in MGTs and encoded as effective Einstein spaces. This includes the Deser–Zumino super-Higgs effect, for instance, for a one-loop potential in a simple but representative model of supergravity. We develop and apply new geometrical techniques that allow us to decouple the gravitational field equations and integrate them in a very general form with the metric and vielbein fields depending on all the spacetime coordinates by means of various generating and integration functions and parameters. We study how solutions in MGTs may be related to the dynamical generation of a gravitino mass and supersymmetry breaking.

Fermion mass mixing and vacuum triviality in the renormalization group procedure for effective particles

Renormalization group procedure for effective particles is applied to the model quantum theory of free fermions to which one adds an interaction in the form of a mass mixing term. If one used a standard approach based on the instant form of dynamics, the theory would suffer from a generic vacuum problem caused by a divergent production of virtual quanta out of a bare vacuum and it would require an adjustment of its degrees of freedom to the added interaction term before quantization, considered a means of avoiding the quantum vacuum problem. In the effective particle approach, the quantum vacuum problem is dealt with instead by using the front form of dynamics, where the pair production is excluded by momentum conservation. The corresponding Hamiltonian includes mass parameters through constraint equations while the required quantum field operators are constructed independently of all mass parameters, including the parameters that appear in the added mass mixing interaction term. Then the masses and states of physical fermions emerge at an end of the non-perturbative calculation that is carried out entirely in one and the same interacting quantum theory with a trivial vacuum and no quantization adjustment. An a priori infinite set of renormalization group equations for all momentum modes of fermion fields is reduced to just one equation for a two-by-two mass squared matrix, thanks to 7 kinematical symmetries of the front form (the instant form has only 6). For strong mass mixing interactions, the fermion model solutions qualitatively differ from the analogous, earlier found boson model solutions by the absence of tachyons.

Commentary on “Predictors of Failed Primary Abdominal Closure in the Trauma Patient with an Open Abdomen”

Abstract : Damage-control laparotomy is the mainstay of therapy for the management of abdominal trauma in physiologically ill patients. The goals of damage-control laparotomy include hemostasis and control of contamination, with some form of temporary abdominal closure (TAC) needed upon completion of the abbreviated laparotomy. Ideally, TAC should be atraumatic, be rapidly and easily applied, minimize the risk of intraabdominal hypertension, control peritoneal effluent, allow for quick reentry into the peritoneum, and maximize future attempts to achieve primary fascial closure. The result of the prolonged open abdomen leads to the loss of abdominal wall domain and the need for skin autografting over viscera with planned ventral hernia. As the open abdomen after injury became more common, many TAC methods were developed to include towel-clip skin closure, suture skin closure, Bogota bag, synthetic mesh, mesh zipper, Wittmann patch, three-layer negative-pressure dressing, fascial sutures, and commercial negative-pressure dressings. The methods that are most commonly used can be classified into two main groups: negative-pressure dressings of varying complexity and cost and techniques that apply traction to the fascia and/or skin to limit retraction and theoretically prevent further domain loss. To date, no method has been borne out to be superior to the other. A review suggested that although the generic three-layer vacuum pack technique (nonadhesive bowel drape, towel, closed suction drains) for TAC is the standard, other methods should be measured against it and the choice of TAC should be a matter of surgeon preference.

Towards constraining of the Horava–Lifshitz gravities

Recently a renormalizable model of gravity has been proposed, which might be a UV completion of General Relativity (GR) or its infra-red modification, probably with a strongly coupled scalar mode. Although the generic vacuum of the theory is anti-de Sitter one, particular limits of the theory allow for the Minkowski vacuum. In this limit (though without consideration of the strongly coupled scalar field) post-Newtonian coefficients of spherically symmetric solutions coincide with those of the General Relativity. Thus the deviations from the convenient GR should be tested beyond the post-Newtonian corrections, that is for a system with strong gravity at astrophysical scales. In this Letter we consider potentially observable properties of black holes in the deformed Horava–Lifshitz gravity with Minkowski vacuum: the gravitational lensing and quasinormal modes. We have showed that the bending angle is seemingly smaller in the considered Horava–Lifshitz gravity than in GR. The quasinormal modes of black holes are longer lived and have larger real oscillation frequency in the Horava–Lifshitz gravity than in GR. These corrections should be observable in the near future experiments on lensing and by gravitational antennas, helping to constrain parameters of the Horava–Lifshitz gravity or to discard it.

Flux tubes on Higgs branches in SUSY gauge theories

We study flux tubes on Higgs branches with curved geometry in supersymmetric gauge theories. As a first example we consider N=1 QED with one flavor of charges and with Higgs branch curved by adding a Fayet–Iliopoulos (FI) term. We show that in a generic vacuum on the Higgs branch flux tubes exist but become “thick”. Their internal structure in the plane orthogonal to the string is determined by “BPS core” formed by heavy fields and long range “tail” associated with light fields living on the Higgs branch. The string tension is given by the tension of “BPS core” plus contribution coming from the “tail”. Next we consider N=2 QCD with gauge group SU(2) and N f =2 flavors of fundamental matter (quarks) with the same mass. We perturb this theory by the mass term for the adjoint field which to the leading order in perturbation parameter do not break N=2 supersymmetry and reduces to FI term. The Higgs branch has Eguchi–Hanson geometry. We work out string solution in the generic vacuum on the Higgs branch and calculate its string tension. We also discuss if these strings can turn into semilocal strings, the possibility related to the confinement/deconfinement phase transition.

Automatic reduction of four-loop bubbles

We give technical details about the computational strategy employed in a recently completed investigation of the four-loop QCD free energy. In particular, the reduction step from generic vacuum bubbles to master integrals is described from a practical viewpoint, for fully massive as well as QED-type integrals.

Tachyon Condensates, Carrollian Contraction of Lorentz Group, and Fundamental Strings

We study the rolling tachyon condensate in the presence of a gauge field. The generic vacuum admits both a rolling tachyon, , and a uniform electric field, , which together affect the effective metric governing the fluctuations of open string modes. If one suppresses the gauge field altogether, the light-cone collapses completely. This is the carrollian limit, with vanishing speed of light and no possible propagation of signals. In the presence of a gauge field, however, the lightcone is squeezed to the shape of a fan, allowing propagation of signals along the direction of ± at speed || ⩽ 1. This shows that there are perturbative degrees of freedom propagating along electric flux lines. Such causal behavior appears to be a very general feature of tachyon effective lagrangian with runway potentials. We speculate on how this may be connected to appearance of fundamental strings.

Gauge and gravitational couplings from modular orbits in orbifold compactifications

We discuss the appearance of modular functions at the one-loop gauge and gravitational couplings in (0,2) non-decomposable N=1 four dimensional orbifold compactifications of the heterotic string. We define the limits for the existence of states causing singularities in the moduli space in the perturbative regime for a generic vacuum of the heterotic string. The “proof” provides evidence for the explanation of the stringy Higgs effect.