bluuebunny/crossref_metadata_2025 huggingface dataset:
Marketing of organic products in southern Poland
Authors: Kuboń Maciej , Olech Elżbieta
Published: March 2018

The article presents an outline of the issue concerning formulation of a marketing strategy and the possibility of using the knowledge on consumers' preferences for organic development of farms and their products on the example of southern Poland. The paper analyses the distribution process of organic food in the aspect of developing innovative marketing strategies. The studies were performed in 50 organic farms and on the example of 100 respondents from the region of southern Poland. In the opinion of the surveyed representatives of the organic food producers, a competitive advantage of their offer depends the most on the health values, brand, reputation, and taste. Moreover, information on products and the form and place of their sale are significant. The analysis shows that the knowledge is the most eagerly obtained from the Internet. Thus, producers should publish their profiles and pages on social media and business portals.
Methane fermentation as a possibility of utilization and energy – efficient management of sewage sludge
Authors: Smurzyńska Anna , Kozłowski Kamil , Cieślik Marta , Brzoski Michał , Chełkowski Dawid , Mazurkiewicz Jakub , Woźniak Ewa
Published: March 2018

Sewage sludge contains organic and biogenic substances that should be used. These materials may also contain toxic substances and heavy metals, and therefore require proper management in accordance with applicable law. Sewage sludge disposal is important for the protection of the environment, but also for the costs associated with the disposal of sludge. There are many technologies that are designed to use the properties of sewage sludge. It should be emphasized, however, that the proposed sewage sludge management technologies require investment outlays. In the present situation, research experiments have been carried out in the Environmental Technology Laboratory of the University of Environmental and Life Sciences in Poznan, indicating the possibility of efficient use of sewage sludge in the methane fermentation process. The use of sewage sludge in the fermentation mix allows the fertilizer to be obtained in the form of fermentation pulp, which also has the same properties as natural fertilizers. It should also be noted that the effect of physicochemical changes is the production of biogas, which is the source of electricity and/or heat. The economic sustainability of the use of sludge (taking into account the current costs of their disposal) is unequivocally positive when co-fermented in an appropriate proportion. The results show that sewage sludge can be successfully used in biogas plants as a co-substrate of fermentation mix. Therefore, the use of sewage sludge in biogas plants not only allows for the safe management and production of fertilizers, but also for the "green" energy.
Economic Assessment of the Technology Harvesting Maize Straw for Biogas Production
Authors: Wojcieszak Dawid , Przybył Jacek , Dach Jacek , Zaborowicz Maciej , Staszak Żaneta
Published: March 2018

The aim of the study was to determine and analyse the costs of harvesting and storage of maize straw for biogas production. The investigations showed that it was the most economical to harvest maize straw with a self-loading wagon equipped with a cutting system and to store it in a field prism. The cost of this technology amounts to €12.5 per Mg d.m. The cost of maize straw harvest with a field chopper and storage in a flexible silo was the highest, amounts to €126.9 per Mg d.m. The research findings can be used for estimating the profitability of harvesting maize straw for energy production and other industrial purposes.
Computer-aided fertilisation using the Nawozy-5 (Fertiliser-5) software
Authors: Cupiał Michał , Kowalczyk Zbigniew
Published: March 2018

The original program Nawozy-5 is an application supporting mineral fertilisation. It is intended for small farms that are not equipped with facilities enabling application of precision agriculture and do not use any commercial software for farm management support. Computational algorithms in the program Nawozy-5 make use of the nutrient balance method. The application calculates requirement for nitrogen, phosphorus, potassium, magnesium, calcium and sulphur and then selects particular fertilisers and calculates their quantities. The program is free of charge and available online on the author’s website www.cupial.mcpk.net.
Models of adaptation of the milking machines systems
Authors: Dmytriv Vasyl , Dmytriv Ihor , Lavryk Yurij , Horodeckyy Ivan
Published: March 2018

Two systems of milking machines were considered - biotechnical and vacuum. Methodology for estimation of efficiency of the "machine-animal" biotechnical system was worked out. The dependences of the efficiency parameters of the technical system operation were analyzed. The KMMO operator load factor of the milking machine was proposed. The factor characterizes the technological process of the machine milking. The analytical dependences were worked out for the simulation of the productivity of milking machines and oscillation of the vacuum-gage pressure. As to the simulation results, when the vacuum pipeline diameter was increased the oscillation of the vacuum-gage pressure decreased. The results of analysis and theoretical researches on technological process of the cow machine milking gave a possibility to define the requirements to the improvement of technological process and technical equipment, which will provide the increase of efficiency of the milking systems. Usage of the developed cyber-physical system of the machine milking of cows will increase the productivity of the milking machine in 1.26…1.85 times. At the vacuum gage pressure oscillation of ΔPvp = 2500 Pa the suction ability of milking machine will be E=4.093 m/s accordingly. The defined index of efficiency of the adapted systems functioning of the milking machine is KBTS2 = 55.3.
Farm size and volume of external transportation services at selected farm businesses
Authors: Kokoszka Stanisław , Daniel Zbigniew
Published: March 2018

The present survey and data analysis confirmed the impact of the farm size (based on the Utilized Agricultural Area) on the volume of external transportation services despite the overall improvement of owned means of transport. The main transport characteristic, i.e. shipment distance increases with the farm size. Hence, the largest farm businesses characterized by higher commercial outputs use external transportation services to a greater extent although they own better quality and higher number of farm vehicles. At the average freight volume transported by external services of 4.37 tons per hectare of the Utilized Agricultural Area, the share of contracted transportation services in the total freight transport increases from 13.95 % in the smallest farms to 28.42 % in the largest farm businesses. This analysis was confirmed by the correlation analysis between the farm size and volume of external transportation services.
Research on power consumption of screw press for pressing of oil from rape seed
Authors: Kovalyshyn Stepan , Tomyuk Vasyl
Published: March 2018

The work highlights the analysis of the influence of technological and structural parameters of the screw press, namely the step of the turns of the screw shaft of its speed and the area of openings for the removal of cake on the energy parameters of the process of oil expression.

Based on the results of the multifactorial experiment, regression dependence allows us to estimate the influence of the parameters and operating modes of the screw press on the power consumption of the screw press and can be used in the process of synthesis and modeling of machines intended for pressing of vegetable oils from oil-containing raw materials. The surfaces of the response of the dependence of the power consumption of the screw press from the area of the openings for the removal of the cake as well as the step of the turns and the speed of the screw shaft have been constructed.

Providing the following parameters of the pressing process: turn pitch of the auger shaft X10 = 21.8 mm; area of openings for oil cake withdrawal X20 = 107.99 mm2; rotation frequency of the auger shaft X30 = 5.12 min -1, the power consumption of the screw press will be 170 W, ensuring the maximum yield of oil q = 36%.
Efficiency of solar radiation conversion in photovoltaic panels
Authors: Kurpaska Sławomir , Knaga Jarosław , Latała Hubert , Sikora Jakub , Tomczyk Wiesław
Published: March 2018

This paper included analysis the conversion efficiency in photovoltaic panels. The tests were done between February and June at a test stand equipped with three commonly used types of photovoltaic panels: poly- and monocrystalline silicon and with semi-conductive layer made of copper (Cu), indium (In), gallium (Ga) and selenium (Se) (CIGS). Five days of each month were selected for a detailed analysis. They were close to the so-called recommended day for calculations in solar power engineering. Efficiency, calculated as the yield of electrical energy in relation to solar radiation energy reaching the panels was made conditional upon solar radiation intensity and ambient temperature. It was found that as solar radiation intensity and ambient temperature increase, the efficiency of solar radiation conversion into electricity is reduced. Correlation dependence was determined for the test data obtained, describing temperature change of panels depending on climatic conditions. It was found that as panel temperature increases, the conversion efficiency is reduced. Within the tested scope of experiment conditions, the efficiency was reduced in the range between 20.1 and 22.8%. The authors also determined the average efficiency values in individual test months together with average ambient conditions of the environment where the process of solar radiation conversion took place.
The design of a prototype system which controls the flow of milk in the collector’s column of an autonomous milking apparatus
Authors: Lis Stanisław , Tomasik Marcin , Juszka Henryk
Published: March 2018

The research paper presents a prototype system controlling the flow of milk in the collection column of an autonomous milking apparatus. In the Matlab®-Simulink program, the simulation model of such a system was created. Its essential operation is illustrated in the block diagrams. The logic verification of the model’s operational accuracy (off-line simulation) did not reveal errors. Therefore a laboratory stand for hardware verification – (on-line simulation) was developed. Within it a virtual feedback loop of the control system (stored in computer memory), with elements of real object control incorporated – in this way a prototype of the device was created. During the hardware verification of the proposed technical solution, operation errors were not observed. In response to certain signals from the measuring elements, the controller correctly calculated control signals for the actuators.
Modelling fatigue assessment at the vehicle driver’s station
Authors: Maksym Piotr , Pawlak Halina
Published: March 2018

The article presents the principles of fatigue assessment modeling in a driver's station using Bayesian networks. One of the causes of road collisions and accidents is fatigue. The factors determining fatigue are age of driver, psychophysical and health condition, time and length of the route being taken. At present, there is no clear criteria for assessing fatigue among professional drivers, so the objective of assessment is to attempt to design and construct a fatigue assessment model using Bayesian network technology.
Modelling assessment of farmers workload
Authors: Pawlak Halina , Maksym Piotr
Published: March 2018

The article presents the principles of modeling the physical load assessment of farmers using Bayesian Network technology. Despite rapid development of mechanization and automation of work processes in agriculture, many farmers use their own physical strength, such as manual handling of loads. There are periods in which a farmer performs several or even a dozen of variety activities during the 24 hours. It often happens that all these activities do in a hurry, without rest, working after several hours a day, which further strengthens his physical load. The variety of activities often causes problems with the use indicators to assess the physical load gauges, so Bayesian Network technology was used to develop the evaluation model.
Influence of fineness level and applied agglomeration pressure of peppermint herb (Mentha piperita L.) on the mechanical properties of the obtained product
Authors: Sadowskaʼ Urszula , Żabiński Andrzej , Mudryk Krzysztof
Published: March 2018

The objective of the conducted study was to evaluate the impact of the pressure agglomeration process of peppermint herb on the mechanical properties of the obtained product. The separated fractions of peppermint with 0.5-2.5 and 2.5-5 mm particles were compacted using a hydraulic press Fritz Heckert EU 20, with pressure 50, 100, 150 and 200 MPa. A closed matrix with the compression chamber diameter of 15.6 mm was used. Every time, a 2-g herb sample (corresponding to the weight of tea used for the production of tea bags) was poured into the matrix. Thus, compacted herb in the form of a straight cylinder was obtained. When producing the agglomerate compaction work was determined. Strength tests of the obtained agglomerate were conducted using the MTS Insight 2 testing machine. The density of the produced agglomerate, its compaction level and strength in the Brazilian test was calculated.

The obtained results indicate that the values of the tested parameters increase with the increase of pressure in the tested range, yet differences occur between the tested herb fractions. Typically, the agglomerate produced from 0.5-2.5 mm fraction is characterized by a greater density, and the higher level of agglomerate compaction is obtained using 2.5-5 mm herb fraction. The highest strength determined using Brazilian test was determined for agglomerate produced from 0.5-5 mm peppermint herb fraction at 200 MPa pressure and 0.5-2.5 mm fraction using 150 and 200 MPa pressure.
Fractional Maxwell model of viscoelastic biological materials
Authors: Stankiewicz Anna
Published: March 2018

This article focuses on fractional Maxwell model of viscoelastic materials, which are a generalization of classic Maxwell model to non-integer order derivatives. To build a fractional Maxwell model when only the noise-corrupted discrete-time measurements of the relaxation modulus are accessible for identification is a basic concern. For fitting the original measurement data an approach is suggested, which is based on approximate Scott Blair fundamental fractional non-integer models, and which means that the data are fitted by solving two dependent but simple linear least-squares problems in two separable time intervals. A complete identification algorithm is presented. The usability of the method to find the fractional Maxwell model of real biological material is shown. The parameters of the fractional Maxwell model of carrot root that approximate the experimental stress relaxation data closely are given.
Analysis of heat source selection for residential buildings in rural areas
Authors: Szul Tomasz
Published: March 2018

The research aiming to check whether the output of currently installed boilers matches the use requirements together with estimation of their energy efficiency was carried out on a group of 84 single-family residential buildings located in rural areas. Heating and hot water energy needs were calculated for each building in order to determine the use requirements. This enabled verification whether the currently installed boilers match the actual use requirements in the buildings. Based on the calculations it was determined that the designed average boiler output in the group of buildings subject to analysis is 15.7 kW, whereas the mean rated output capacity of boilers installed therein is 25.4 kW. On average, the output capacity of the installed boilers exceeds the use requirements for the buildings by 60%. To calculate the energy efficiency of boilers, the mean annual boiler output capacity use coefficient was determined. For boilers selected on the basis of standard calculations, the mean coefficient is 0.47. For boilers currently in use it is 0.31, less than the above figure. The above calculations show that if boilers were correctly selected in compliance to the building needs, then the average estimated seasonal efficiency of 65% would be feasible. However, in the current state the achievable efficiency is approx. 55%.
Determination of the Strong Coupling Constant by the ALPHA Collaboration
Authors: Korzec Tomasz
Published: March 2018

A high precision determination of the strong coupling constant in the MS scheme at the Z-mass scale, using low energy quantities, namely pion/kaon decay constants and masses, as experimental input is presented. The computation employs two different massless finite volume renormalization schemes to non-perturbatively trace the scale dependence of the respective running couplings from a scale of about 200 MeV to 100 GeV. At the largest energies perturbation theory is reliable. At high energies the Schrödinger-Functional scheme is used, while the running at low and intermediate energies is computed in a novel renormalization scheme based on an improved gradient flow. Large volume Nf = 2 + 1 QCD simulations by CLS are used to set the overall scale. The result is compared to world averages by FLAG and the PDG.
A precise determination of the HVP contribution to the muon anomalous magnetic moment from lattice QCD
Authors: Lehner Christoph
Published: March 2018

In this talk I present the current status of a precise first-principles calculation of the quark connected, quark disconnected, and leading QED and strong isospin-breaking contributions to the leading-order hadronic vacuum polarization by the RBC and UKQCD collaborations. The lattice data is also combined with experimental e+e− scattering data, consistency between the two datasets is checked, and a combined result with smaller error than the lattice data and e+e− scattering data individually is presented.
Hadronic light-by-light contribution to (g - 2)μ: a dispersive approach
Authors: Colangelo Gilberto , Hoferichter Martin , Procura Massimiliano , Stoffer Peter
Published: March 2018

After a brief introduction on ongoing experimental and theoretical activities on (g - 2)μ, we report on recent progress in approaching the calculation of the hadronic light-by-light contribution with dispersive methods. General properties of the four-point function of the electromagnetic current in QCD, its Lorentz decomposition and dispersive representation are discussed. On this basis a numerical estimate for the pion box contribution and its rescattering corrections is obtained. We conclude with an outlook for this approach to the calculation of hadronic light-by-light.
Optimization of the Brillouin operator on the KNL architecture
Authors: Dürr Stephan
Published: March 2018

Experiences with optimizing the matrix-times-vector application of the Brillouin operator on the Intel KNL processor are reported. Without adjustments to the memory layout, performance figures of 360 Gflop/s in single and 270 Gflop/s in double precision are observed. This is with Nc = 3 colors, Nv = 12 right-hand-sides, Nthr = 256 threads, on lattices of size 323 × 64, using exclusively OMP pragmas. Interestingly, the same routine performs quite well on Intel Core i7 architectures, too. Some observations on the much harderWilson fermion matrix-times-vector optimization problem are added.
Ergodicity of the LLR method for the Density of States
Authors: Cossu Guido , Lucini Biagio , Pellegrini Roberto , Rago Antonio
Published: March 2018

The LLR method is a novel algorithm that enables us to evaluate the density of states in lattice gauge theory. We present our study of the ergodicity properties of the LLR algorithm for the model of Yang Mills SU(3). We show that the use of the replica exchange method alleviates significantly the topological freeze-out that severely affects other algorithms.
MILC Code Performance on High End CPU and GPU Supercomputer Clusters
Authors: DeTar Carleton , Gottlieb Steven , Li Ruizi , Toussaint Doug
Published: March 2018

With recent developments in parallel supercomputing architecture, many core, multi-core, and GPU processors are now commonplace, resulting in more levels of parallelism, memory hierarchy, and programming complexity. It has been necessary to adapt the MILC code to these new processors starting with NVIDIA GPUs, and more recently, the Intel Xeon Phi processors. We report on our efforts to port and optimize our code for the Intel Knights Landing architecture. We consider performance of the MILC code with MPI and OpenMP, and optimizations with QOPQDP and QPhiX. For the latter approach, we concentrate on the staggered conjugate gradient and gauge force. We also consider performance on recent NVIDIA GPUs using the QUDA library.
CLS 2+1 flavor simulations at physical light-and strange-quark masses
Authors: Mohler Daniel , Schaefer Stefan , Simeth Jakob
Published: March 2018

We report recent efforts by CLS to generate an ensemble with physical lightand strange-quark masses in a lattice volume of 192 × 963atβ= 3:55 corresponding to a lattice spacing of 0:064 fm. This ensemble is being generated as part of the CLS 2+1 flavor effort with improved Wilson fermions. Our simulations currently cover 5 lattice spacings ranging from 0:039 fm to 0:086 fm at various pion masses along chiral trajectories with either the sum of the quark masses kept fixed, or with the strange-quark mass at the physical value. The current status of simulations is briefly reviewed, including a short discussion of measured autocorrelation times and of the main features of the simulations. We then proceed to discuss the thermalization strategy employed for the generation of the physical quark-mass ensemble and present first results for some simple observables. Challenges encountered in the simulation are highlighted.
Particle Projection Using a Complex Langevin Method
Authors: Shill Christopher R. , Drut Joaquín E.
Published: March 2018

Using complex stochastic quantization, we implement a particle-number projection technique on the partition function of spin-1/2 fermions at finite temperature on the lattice. We discuss the method, its application towards obtaining the thermal properties of finite Fermi systems in three spatial dimensions, and results for the first five virial coefficients of one-dimensional, attractively interacting fermions.
Phases of a strongly coupled four-fermion theory
Authors: Schaich David , Catterall Simon
Published: March 2018

We present ongoing investigations of a four-dimensional lattice field theory with four massless reduced staggered fermions coupled through an SU(4)-invariant fourfermion interaction. As in previous studies of four-fermion and Higgs–Yukawa models with different lattice fermion discretizations, we observe a strong-coupling phase in which the system develops a mass gap without breaking any lattice symmetry. This symmetric strong-coupling phase is separated from the symmetric weak-coupling phase by a narrow region of four-fermi coupling in which the system exhibits long-range correlations.
Testing Fermion Universality at a Conformal Fixed Point
Authors: Hasenfratz Anna , Rebbi Claudio , Witzel Oliver
Published: March 2018

Universality of various fermion formulations is well established in QCD-like theories defined around the perturbative g2 = 0 fixed point. These arguments do not apply for conformal systems that exhibit an infrared fixed point at non-vanishing g2 coupling. We investigate the step scaling function for systems with 10 or 12 fundamental flavors using domain wall fermions and compare it to perturbative predictions. We test universality by contrasting our findings to results published in the literature based on staggered fermions.
Extracting the Single-Particle Gap in Carbon Nanotubes with Lattice Quantum Monte Carlo
Authors: Berkowitz Evan , Körber Christopher , Krieg Stefan , Labus Peter , Lähde Timo A. , Luu Thomas
Published: March 2018

We show how lattice Quantum Monte Carlo simulations can be used to calculate electronic properties of carbon nanotubes in the presence of strong electron-electron correlations. We employ the path integral formalism and use methods developed within the lattice QCD community for our numerical work and compare our results to empirical data of the Anti-Ferromagnetic Mott Insulating gap in large diameter tubes.
Topological susceptibility in 2+1-flavor QCD with chiral fermions
Authors: Aoki Sinya , Cossu Guido , Fukaya Hidenori , Hashimoto Shoji , Kaneko Takashi
Published: March 2018

We compute the topological susceptibility Xt of 2+1-flavor lattice QCD with dynamical Möbius domain-wall fermions, whose residual mass is kept at 1 MeV or smaller. In our analysis, we focus on the fluctuation of the topological charge density in a “slab” sub-volume of the simulated lattice, as proposed by Bietenholz et al. The quark mass dependence of our results agrees well with the prediction of the chiral perturbation theory, from which the chiral condensate is extracted. Combining the results for the pion mass Mπ and decay constant Fπ, we obtain Xt = 0.227(02)(11)M2πF2π at the physical point, where the first error is statistical and the second is systematic.
Nπ scattering in the Roper channel
Authors: Padmanath M. , Lang C. B. , Leskovec Luka , Prelovsek Sasa
Published: March 2018

We present results from our recent lattice QCD study of Nπ scattering in the positive-parity nucleon channel, where the puzzling Roper resonance N*(1440) resides in experiment. Using a variety of hadron operators, that include qqq-like, Nπ in p-wave and Nσ in s-wave, we systematically extract the excited lattice spectrum in the nucleon channel up to 1.65 GeV. Our lattice results indicate that Nπ scattering in the elastic approximation alone does not describe a low-lying Roper. Coupled channel effects between Nπ and Nππ seem to be crucial to render a low-lying Roper in experiment, reinforcing the notion that this state could be a dynamically generated resonance. After giving a brief motivation for studying the Roper channel and the relevant technical details to this study, we will discuss the results and the conclusions based on our lattice investigation and in comparison with other lattice calculations.
Baryon interactions from lattice QCD with physical quark masses – Nuclear forces and ΞΞ forces –
Authors: Doi Takumi , Iritani Takumi , Aoki Sinya , Gongyo Shinya , Hatsuda Tetsuo , Ikeda Yoichi , Inoue Takashi , Ishii Noriyoshi , Miyamoto Takaya , Nemura Hidekatsu , Sasaki Kenji
Published: March 2018

We present the latest lattice QCD results for baryon interactions obtained at nearly physical quark masses. Nf = 2 + 1 nonperturbatively O(a)-improved Wilson quark action with stout smearing and Iwasaki gauge action are employed on the lattice of (96a)4 ≃(8.1fm)4 with a-1 ≃2.3 GeV, where mπ ≃146 MeV and mK ≃525 MeV. In this report, we study the two-nucleon systems and two-Ξ systems in 1S0 channel and 3S1-3D1 coupled channel, and extract central and tensor interactions by the HAL QCD method. We also present the results for the NΩ interaction in 5S2 channel which is relevant to the NΩ pair-momentum correlation in heavy-ion collision experiments.
Charmonium-nucleon interactions from the time-dependent HAL QCD method
Authors: Sugiura Takuya , Ikeda Yoichi , Ishii Noriyoshi
Published: March 2018

The charmonium-nucleon effective central interactions have been computed by the time-dependent HAL QCD method. This gives an updated result of a previous study based on the time-independent method, which is now known to be problematic because of the difficulty in achieving the ground-state saturation. We discuss that the result is consistent with the heavy quark symmetry. No bound state is observed from the analysis of the scattering phase shift; however, this shall lead to a future search of the hidden-charm pentaquarks by considering channel-coupling effects.
Baryon interactions from lattice QCD with physical masses — strangeness S = -1 sector —
Authors: Nemura Hidekatsu , Aoki Sinya , Doi Takumi , Gongyo Shinya , Hatsuda Tetsuo , Ikeda Yoichi , Inoue Takashi , Iritani Takumi , Ishii Noriyoshi , Miyamoto Takaya , Sasaki Kenji
Published: March 2018

We present our recent results of baryon interactions with strangeness S = −1 based on Nambu-Bethe-Salpeter (NBS) correlation functions calculated fromlattice QCD with almost physical quark masses corresponding to (mk,mk) ≈ (146, 525) MeV and large volume (La)4 ≈ (96a)4 ≈ (8.1 fm)4. In order to perform a comprehensive study of baryon interactions, a large number of NBS correlation functions from NN to ΞΞ are calculated simultaneously by using large scale computer resources. In this contribution, we focus on the strangeness S = −1 channels of the hyperon interactions by means of HAL QCD method. Four sets of three potentials (the 3S1 − 3 D1 central, 3S1 − 3 D1 tensor, and the 1S0 central potentials) are presented for the ∑N − ∑N (the isospin I = 3/2) diagonal, the ∧N − ∧N diagonal, the ∧N → ∑N transition, and the ∑N − ∑N (I = 1/2) diagonal interactions. Scattering phase shifts for ∑N (I = 3/2) system are presented.
Heavy hadrons spectra on lattice using NRQCD
Authors: Mohanta Protick , Basak Subhasish
Published: March 2018

Comparison of radial excitation energies to masses show that the velocity of b quark is very non-relativistic in bottomonium states. In a mixed system like charmed B meson, the b quark has less velocity than it has in bottomonium states and in strange B meson it is even slower. So one can use NRQCD for the b quark in those systems. Using overlap and hisq action for the s and c quarks and NRQCD for b quark we simulated spectra of charmed and strange B mesons and also few other baryons.
Leading isospin-breaking corrections to meson masses on the lattice
Authors: Giusti Davide , Lubicz Vittorio , Martinelli Guido , Sanfilippo Francesco , Simula Silvano , Tantalo Nazario , Tarantino Cecilia
Published: March 2018

We present a study of the isospin-breaking (IB) corrections to pseudoscalar (PS) meson masses using the gauge configurations produced by the ETM Collaboration with Nf = 2+1+1 dynamical quarks at three lattice spacings varying from 0.089 to 0.062 fm. Our method is based on a combined expansion of the path integral in powers of the small parameters [see formula in PDF] and αem, where [see formula in PDF] is the renormalized quark mass and αem the renormalized fine structure constant. We obtain results for the pion, kaon and Dmeson mass splitting; for the Dashen’s theorem violation parameters ϵγ(MM, 2 GeV), ϵπ0 ϵK0(MS, 2 GeV) for the light quark masses [see formula in PDF] for the flavour symmetry breaking parameters R(MS, 2 GeV) and Q(MS, 2 GeV) and for the strong IB effects on the kaon decay constants.
Connected and disconnected contributions to nucleon axial form factors using Nf = 2 twisted mass fermions at the physical point
Authors: Alexandrou Constantia , Constantinou Martha , Hadjiyiannakou Kyriakos , Jansen Karl , Kallidonis Christos , Koutsou Giannis , Vaquero Avilés-Casco Alejandro
Published: March 2018

We present results on the isovector and isoscalar nucleon axial form factors including disconnected contributions, using an ensemble of Nf = 2 twisted mass cloverimproved Wilson fermions simulated with approximately the physical value of the pion mass. The light disconnected quark loops are computed using exact deflation, while the strange and the charm quark loops are evaluated using the truncated solver method. Techniques such as the summation and the two-state fits have been employed to access ground-state dominance.
Lattice QCD results for the HVP contribution to the anomalous magnetic moments of leptons
Authors:   Budapest-Marseille-Wuppertal Collaboration, Borsanyi Szabolcs , Fodor Zoltan , Kawanai Taichi , Krieg Stefan , Lellouch Laurent , Malak Rehan , Miura Kohtaroh , Szabo Kalman K. , Torrero Christian , Toth Balint C.
Published: March 2018

We present lattice QCD results by the Budapest-Marseille-Wuppertal (BMW) Collaboration for the leading-order contribution of the hadron vacuum polarization (LOHVP) to the anomalous magnetic moments of all charged leptons. Calculations are performed with u, d, s and c quarks at their physical masses, in volumes of linear extent larger than 6 fm, and at six values of the lattice spacing, allowing for controlled continuum extrapolations. All connected and disconnected contributions are calculated for not only the muon but also the electron and tau anomalous magnetic moments. Systematic uncertainties are thoroughly discussed and comparisons with other calculations and phenomenological estimates are made.
Electric Dipole Moment Results from lattice QCD
Authors: Dragos Jack , Luu Thomas , Shindler Andrea , de Vries Jordy
Published: March 2018

We utilize the gradient flow to define and calculate electric dipole moments induced by the strong QCD θ-term and the dimension-6 Weinberg operator. The gradient flow is a promising tool to simplify the renormalization pattern of local operators. The results of the nucleon electric dipole moments are calculated on PACS-CS gauge fields (available from the ILDG) using Nf = 2+1, of discrete size 323×64 and spacing a ≃ 0.09 fm. These gauge fields use a renormalization-group improved gauge action and a nonperturbatively O(a) improved clover quark action at β = 1.90, with cSW = 1.715. The calculation is performed at pion masses of mπ ≃ 411, 701 MeV.
Isospin Breaking Corrections to the HVP with Domain Wall
Fermions
Authors: Boyle Peter , Guelpers Vera , Harrison James , Juettner Andreas , Lehner Christoph , Portelli Antonin , Sachrajda Christopher
Published: March 2018

We present results for the QED and strong isospin breaking corrections to the hadronic vacuum polarization using Nf = 2 + 1 Domain Wall fermions. QED is included in an electro-quenched setup using two different methods, a stochastic and a perturbative approach. Results and statistical errors from both methods are directly compared with each other.
Nucleon average quark momentum fraction with Nf = 2+1 Wilson fermions
Authors: Ottnad Konstantin , Harris Tim , Meyer Harvey , von Hippel Georg , Wilhelm Jonas , Wittig Hartmut
Published: March 2018

We report on an analysis of the average quark momentum fraction of
the nucleon and related quantities using
Nf = 2 + 1 Wilson fermions. Computations
are performed on four CLS ensembles covering three values of the
lattice spacing at pion masses down to Mπ ≈ 200 MeV. Several source-sink separations (~ 1:0 fm to ~ 1:4 fm) are used to assess the excited-state contamination. To gain further insight, the generalized pencil-of-functions approach has been implemented to reduce the excited-state contamination in the relevant two-and three-point functions. Preliminary results are shown for the isovector nucleon charges from vector, axial vector and tensor derivative (twist-2) operators.
Perturbative matching of continuum and lattice quasi-distributions
Authors: Ishikawa Tomomi
Published: March 2018

Matching of the quasi parton distribution functions between continuum and lattice is addressed using lattice perturbation theory specifically withWilson-type fermions. The matching is done for nonlocal quark bilinear operators with a straightWilson line in a spatial direction. We also investigate operator mixing in the renormalization and possible O(a) operators for the nonlocal operators based on a symmetry argument on lattice.
A lattice calculation of the hadronic vacuum polarization contribution to (g – 2)µ
Authors: Della Morte M. , Francis A. , Gérardin A. , Gülpers V. , Herdoíza G. , von Hippel G. , Horch H. , Jäger B. , Meyer H.B. , Nyffeler A. , Wittig H.
Published: March 2018

We present results of calculations of the hadronic vacuum polarisation contribution to the muon anomalous magnetic moment. Specifically, we focus on controlling the infrared regime of the vacuum polarisation function. Our results are corrected for finite-size effects by combining the Gounaris-Sakurai parameterisation of the timelike pion form factor with the Lüscher formalism. The impact of quark-disconnected diagrams and the precision of the scale determination is discussed and included in our final result in two-flavour QCD, which carries an overall uncertainty of 6%. We present preliminary results computed on ensembles with Nf = 2 + 1 dynamical flavours and discuss how the long-distance contribution can be accurately constrained by a dedicated spectrum calculation in the iso-vector channel.
Dual simulation of the massless lattice Schwinger model with topological term and non-zero chemical potential
Authors: Göschl Daniel
Published: March 2018

We discuss simulation strategies for the massless lattice Schwinger model with a topological term and finite chemical potential. The simulation is done in a dual representation where the complex action problem is solved and the partition function is a sum over fermion loops, fermion dimers and plaquette-occupation numbers. We explore strategies to update the fermion loops coupled to the gauge degrees of freedom and check our results with conventional simulations (without topological term and at zero chemical potential), as well as with exact summation on small volumes. Some physical implications of the results are discussed.
Critical endline of the finite temperature phase transition for 2+1 flavor QCD away from the SU(3)-flavor symmetric point
Authors: Nakamura Yoshifumi , Kuramashi Yoshinobu , Takeda Shinji
Published: March 2018

We investigate the critical end line of the finite temperature phase transition of QCD away from the SU(3)-flavor symmetric point at zero chemical potential. We employ the renormalization-group improved Iwasaki gauge action and non-perturbatively O(a)- improved Wilson-clover fermion action. The critical end line is determined by using the intersection point of kurtosis, employing the multi-parameter, multi-ensemble reweighting method at the temporal size NT = 6 and lattice spacing as low as a ≈0.19 fm.
Confinement-deconfinement transition in dense SU(2) QCD
Authors: Bornyakov V. G. , Braguta V. V. , Ilgenfritz E.-M. , Kotov A. Yu. , Kudrov I. E. , Molochkov A. V. , Nikolaev A. A. , Rogalyov R. N.
Published: March 2018

In this report we study the properties of the dense SU(2) QCD. The lattice simulations are carried out with improved gauge action and smaller lattice spacing as compared to our previous work. This allowed us to approach closer to the continuum limit and reach larger densities without lattice artifacts. We measured string tension and Polyakov loop as functions of chemical potential and temperature. At suffciently large baryon density and zero temperature we observe confinement/deconfinement transition which manifests itself as a vanishing of the string tension and rising of the Polyakov loop.
Accurate simulation of the finite density lattice Thirring model
Authors: Rantaharju Jarno
Published: March 2018

We present a study of the finite density lattice Thirring model in 1+1 dimensions using the world-line/fermion-bag algorithm. The model has features similar to QCD and provides a test case for exploring the accuracy of various methods of solving sign problems. In the massless limit and with open boundary conditions we show that the sign problem is an artifact of the auxiliary field approach and is completely eliminated in the fermion bag approach. With periodic boundary conditions the sign problem is mild in the fermion bag method. We present accurate results for various quantities in the model that can be used as a benchmark for comparison with other methods of solving sign problems.
Energy-momentum tensor correlation function in Nf = 2 + 1 full QCD at finite temperature
Authors: Taniguchi Yusuke , Ejiri Shinji , Kanaya Kazuyuki , Kitazawa Masakiyo , Suzuki Asobu , Suzuki Hiroshi , Umeda Takashi
Published: March 2018

We measure correlation functions of the nonperturbatively renormalized energy-momentum tensor in Nf = 2 + 1 full QCD at finite temperature by applying the gradient flow method both to the gauge and quark fields. Our main interest is to study the conservation law of the energy-momentum tensor and to test whether the linear response relation is properly realized for the entropy density. By using the linear response relation we calculate the specific heat from the correlation function. We adopt the nonperturba-tively improved Wilson fermion and Iwasaki gauge action at a fine lattice spacing = 0:07 fm. In this paper the temperature is limited to a single value T ≃ 232 MeV. The u, d quark mass is rather heavy with mπ=mρ ≃ 0:63 while the s quark mass is set to approximately its physical value.
Medium effects and parity doubling of hyperons across the deconfinement phase transition
Authors: Aarts Gert , Allton Chris , Boni Davide De , Hands Simon , Jäger Benjamin , Praki Chrisanthi , Skullerud Jon-Ivar
Published: March 2018

We analyse the behaviour of hyperons with strangeness S = –1,–2,–3 in the hadronic and quark gluon plasma phases, with particular interest in parity doubling and its emergence as the temperature grows. This study uses our FASTSUM anisotropic Nf = 2+1 ensembles, with four temperatures below and four above the deconfinement transition temperature, Tc. The positive-parity groundstate masses are found to be largely temperature independent below Tc, whereas the negative-parity ones decrease considerably as the temperature increases. Close to the transition, the masses are almost degenerate, in line with the expectation from chiral symmetry restoration. This may be of interest for heavy-ion phenomenology. In particular we show an application of this effect to the Hadron Resonance Gas model. A clear signal of parity doubling is found above Tc in all hyperon channels, with the strength of the effect depending on the number of s-quarks in the baryons.
QCD at finite isospin chemical potential
Authors: Brandt Bastian B. , Endrődi Gergely , Schmalzbauer Sebastian
Published: March 2018

We investigate the properties of QCD at finite isospin chemical potential at zero and non-zero temperatures. This theory is not affected by the sign problem and can be simulated using Monte-Carlo techniques. With increasing isospin chemical potential and temperatures below the deconfinement transition the system changes into a phase where charged pions condense, accompanied by an accumulation of low modes of the Dirac operator. The simulations are enabled by the introduction of a pionic source into the action, acting as an infrared regulator for the theory, and physical results are obtained by removing the regulator via an extrapolation. We present an update of our study concerning the associated phase diagram using 2+1 flavours of staggered fermions with physical quark masses and the comparison to Taylor expansion. We also present first results for our determination of the equation of state at finite isospin chemical potential and give an example for a cosmological application. The results can also be used to gain information about QCD at small baryon chemical potentials using reweighting with respect to the pionic source parameter and the chemical potential and we present first steps in this direction.
Axial U(1) symmetry at high temperature in 2-flavor lattice QCD
Authors: Suzuki Kei , Aoki Sinya , Aoki Yasumichi , Cossu Guido , Fukaya Hidenori , Hashimoto Shoji
Published: March 2018

We investigate the axial U(1)A symmetry breaking above the critical temperature in two-flavor lattice QCD. The ensembles are generated with dynamical Möbius domain-wall or reweighted overlap fermions. The U(1)A susceptibility is extracted from the low-modes spectrum of the overlap Dirac eigenvalues. We show the quark mass and temperature dependences of U(1)A susceptibility. Our results at T = 220MeV imply that the U(1)A symmetry is restored in the chiral limit. Its coincidence with vanishing topological susceptibility is observed.
Paths to equilibrium in non-conformal collisions
Authors: Attems Maximilian , Bea Yago , Casalderrey-Solana Jorge , Mateos David , Santos-Oliván Daniel , Sopuerta Carlos F. , Triana Miquel , Zilhão Miguel
Published: March 2018

Ever since fast hydrodynamization has been observed in heavy ion collisions the understanding of the hot early out-of-equilibrium stage of such collisions has been a topic of intense research. We use the gauge/gravity duality to model the creation of a strongly coupled Quark-Gluon plasma in a non-conformal gauge theory. This numerical relativity study is the first non-conformal holographic simulation of a heavy ion collision and reveals the existence of new relaxation channels due to the presence of non-vanishing bulk viscosity. We study shock wave collisions at different energies in gauge theories with different degrees of non-conformality and compare three relaxation times which can occur in different orderings: the hydrodynamization time (when hydrodynamics becomes applicable), the EoSization time (when the average pressure approaches its equilibrium value) and the condensate relaxation time (when the expectation value of a scalar operator approaches its equilibrium value). We find that these processes can occur in several different orderings. In particular, the condensate can remain far from equilibrium even long after the plasma has hydrodynamized and EoSized.
Progress on Complex Langevin simulations of a finite density matrix model for QCD
Authors: Bloch Jacques , Glesaaen Jonas , Verbaarschot Jacobus , Zafeiropoulos Savvas
Published: March 2018

We study the Stephanov model, which is an RMT model for QCD at finite density, using the Complex Langevin algorithm. Naive implementation of the algorithm shows convergence towards the phase quenched or quenched theory rather than to intended theory with dynamical quarks. A detailed analysis of this issue and a potential resolution of the failure of this algorithm are discussed. We study the effect of gauge cooling on the Dirac eigenvalue distribution and time evolution of the norm for various cooling norms, which were specifically designed to remove the pathologies of the complex Langevin evolution. The cooling is further supplemented with a shifted representation for the random matrices. Unfortunately, none of these modifications generate a substantial improvement on the complex Langevin evolution and the final results still do not agree with the analytical predictions.
Ward identities in N = 1 supersymmetric SU(3) Yang-Mills theory on the lattice
Authors: Ali Sajid , Bergner Georg , Gerber Henning , Giudice Pietro , Montvay István , Münster Gernot , Piemonte Stefano , Scior Philipp
Published: March 2018

The introduction of a space-time lattice as a regulator of field theories breaks symmetries associated with continuous space-time, i.e. Poincaré invariance and supersymmetry. A non-zero gluino mass in the supersymmetric Yang-Mills theory causes an additional soft breaking of supersymmetry. We employ the lattice form of SUSY Ward identities, imposing that their continuum form would be recovered when removing the lattice regulator, to obtain the critical hopping parameter where broken symmetries can be recovered.
Testing the holographic principle using lattice simulations
Authors: Jha Raghav G. , Catterall Simon , Schaich David , Wiseman Toby
Published: March 2018

The lattice studies of maximally supersymmetric Yang-Mills (MSYM) theory at strong coupling and large N is important for verifying gauge/gravity duality. Due to the progress made in the last decade, based on ideas from topological twisting and orbifolding, it is now possible to study these theories on the lattice while preserving an exact supersymmetry on the lattice. We present some results from the lattice studies of two-dimensional MSYM which is related to Type II supergravity. Our results agree with the thermodynamics of different black hole phases on the gravity side and the phase transition (Gregory–Laflamme) between them.