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The article informs about describing the basic ingredients of universe, the standard model of particle physics has many shortcomings, explain dark matter, the invisible dark energy, which seems to be driving the accelerating expansion of the universe. Topics include transform into a strange quark and two muons were plagued by uncerstainties from quantum chromodynamics (QCD); and how matter survived the big bang, being annihilated by an equal amount of antimatter.

The article discusses the Axion Dark Matter Experiment (ADMX) as researchers entered its most sensitive phase yet in its searchfor invisible particles to explain the universe's hidden mass. Topics include weakly interacting massive particle (WIMP), concepts of quantum chromodynamics (QCD), and problems related to charge parity (CP). Also discussed is use of superconducting quantum-interference devices (SQUIDs).

We propose improved estimators to compute the reweighting factors which are needed for lattice QCD calculations that rely on twisted-mass reweighting for the light quark contribution and the Rational Hybrid Monte Carlo (RHMC) algorithm for non-degenerate quark masses. This is the case for a number of modern large-scale simulations based on O (a) improved Wilson fermions. We find a significant reduction of uncertainties for the reweighting factors at similar computational cost compared to the conventional estimation. This leads to a significant increase in precision for phenomenologically relevant observables with high correlation to the low eigenmodes of the Wilson-Dirac operator in the presence of exceptionally small eigenvalues. Supplementary details regarding the spectral gap of the light quark Dirac operator on the 2 + 1 flavor large-volume ensembles explored in this study can be found in an accompanying appendix. [ABSTRACT FROM AUTHOR]

The rise of exascale supercomputers has fueled competition among GPU vendors, driving lattice QCD developers to write code that supports multiple APIs. Moreover, new developments in algorithms and physics research require frequent updates to existing software. These challenges have to be balanced against constantly changing personnel. At the same time, there is a wide range of applications for HISQ fermions in QCD studies. This situation encourages the development of software featuring a HISQ action that is flexible, high-performing, open source, easy to use, and easy to adapt. In this technical paper, we explain the design strategy, provide implementation details, list available algorithms and modules, and show key performance indicators for SIMULATeQCD, a simple multi-GPU lattice code for large-scale QCD calculations, mainly developed and used by the HotQCD collaboration. The code is publicly available on GitHub. Program Title: SIMULATeQCD CPC Library link to program files: https://doi.org/10.17632/ytgycy9nc3.1 Developer's repository link: https://github.com/LatticeQCD/SIMULATeQCD Licensing provisions: MIT Programming language: C++, CUDA, HIP Nature of problem: Quantum chromodynamics (QCD) is the fundamental theory behind the strong force, one of the four fundamental forces in nature. It describes interactions, mediated by gluons, between quarks, the elementary particles that build up protons, neutrons and other hadrons. One of its unique features is asymptotic freedom: with increasing energy, the interaction strength or coupling between quarks and gluons weakens, which enables studying QCD with peturbation theory. At lower energy scales, however, the strong coupling between quarks and gluons causes perturbation theory to break down, and other tools, such as lattice QCD, need to be employed to obtain QCD predictions. Solution method: Lattice QCD is a technique to solve QCD non-perturbatively by discretizing space and time onto a four-dimensional grid. The QCD path integral is thereby rendered finite dimensional and can be evaluated numerically via Monte Carlo methods. In this paper, we present SIMULATeQCD, a C++ code to perform lattice QCD calculations on multiple GPUs, supporting multiple APIs. SIMULATeQCD implements various Monte Carlo sampling methods ranging from sampling of purely gluonic configurations to fully dynamical quark simulations with the Highly Improved Staggered Quark (HISQ) discretization. Modules for measuring various physical observables on these samples are also available. [ABSTRACT FROM AUTHOR]

Estimating the trace of the inverse of a large matrix is an important problem in lattice quantum chromodynamics. A multilevel Monte Carlo method is proposed for this problem that uses different degree polynomials for the levels. The polynomials are developed from the GMRES algorithm for solving linear equations. To reduce orthogonalization expense, the highest degree polynomial is a composite or double polynomial found with a polynomial preconditioned GMRES iteration. Added to some of the Monte Carlo pieces is deflation of eigenvalues that reduces the variance. Deflation is also used for finding a reduced degree deflated polynomial. The new Multipolynomial Monte Carlo method can significantly improve the trace computation for matrices that have a difficult spectrum due to small eigenvalues. [ABSTRACT FROM AUTHOR]

The article looks at research in particle physics, focusing on the implications of the small difference in mass between protons and neutrons. It discusses developments in the fields of quantum chromodynamics and quantum electrodynamics in areas including quark interactions,and gluons, Other topics include the uncertainty principle of quantum mechanics and the Higgs boson.

The article discusses particles called gluons, which keep protons and neutrons intact, and their mysterious nature. Topics include the mystery of how particles inside protons and neutrons, called quarks and gluons, interact with one another to generate the range of properties and behaviors displayed by protons, neutrons, and hadrons, which are made up of quarks and antiquarks. Topics include the origin of a proton's mass, how gluons bind, and the quantum chromodynamics (QCD) theory.

Machine learning techniques, in particular the so-called normalizing flows, are becoming increasingly popular in the context of Monte Carlo simulations as they can effectively approximate target probability distributions. In the case of lattice field theories (LFT) the target distribution is given by the exponential of the action. The common loss function's gradient estimator based on the "reparametrization trick" requires the calculation of the derivative of the action with respect to the fields. This can present a significant computational cost for complicated, non-local actions like e.g. fermionic action in QCD. In this contribution, we propose an estimator for normalizing flows based on the REINFORCE algorithm that avoids this issue. We apply it to two dimensional Schwinger model with Wilson fermions at criticality and show that it is up to ten times faster in terms of the wall-clock time as well as requiring up to 30% less memory than the reparameterization trick estimator. It is also more numerically stable allowing for single precision calculations and the use of half-float tensor cores. We present an in-depth analysis of the origins of those improvements. We believe that these benefits will appear also outside the realm of the LFT, in each case where the target probability distribution is computationally intensive. [ABSTRACT FROM AUTHOR]

Researchers from Lund University in Sweden have published new data on simplifying calculations in high energy physics. They have developed a method called the chirality-flow formalism, combined with good choices of gauge reference vectors, which allows for immediate calculation of amplitudes corresponding to Feynman diagrams. This method has been shown to significantly speed up calculations in a proof of concept implementation. The researchers have extended this analysis to quantum chromodynamics (QCD) and have found that the chirality-flow formalism can also be applied to simplify calculations involving massive quarks. Overall, this method offers a clear speedup for treating the Lorentz structure at high multiplicities. [Extracted from the article]

The calculation of disconnected diagram contributions to physical signals is a computationally expensive task in Lattice QCD. To extract the physical signal, the trace of the inverse Lattice Dirac operator, a large sparse matrix, must be stochastically estimated. Because the variance of the stochastic estimator is typically large, variance reduction techniques must be employed. Multilevel Monte Carlo (MLMC) methods reduce the variance of the trace estimator by utilizing a telescoping sequence of estimators. Frequency Splitting is one such method that uses a sequence of inverses of shifted operators to estimate the trace of the inverse lattice Dirac operator, however there is no a priori way to select the shifts that minimize the cost of the multilevel trace estimation. In this article, we present a sampling and interpolation scheme that is able to predict the variances associated with Frequency Splitting under displacements of the underlying space time lattice. The interpolation scheme is able to predict the variances to high accuracy and therefore chooses shifts that correspond to an approximate minimum of the cost for the trace estimation. We show that Frequency Splitting with the chosen shifts displays significant speedups over multigrid deflation, and that these shifts can be used for multiple configurations within the same ensemble with no penalty to performance. • We approximately minimize the cost for the multilevel Monte Carlo method Frequency Splitting with lattice displacements. • The set of shifts that approximately minimizes the cost of Frequency Splitting is given by a new interpolation scheme. • Frequency Splitting with the found shifts displays significant speed up over multigrid deflation. • For this application, we demonstrate that the shifts can be safely reused for multiple configurations from the same ensemble. [ABSTRACT FROM AUTHOR]

This article reports that for 30 years, researchers have been battling to make sense of the strong force, the glue that sticks protons and neutrons together in nuclei. Yet their best mathematical theory has been so complex that no one could turn the dense equations into useful predictions. Now all that is changing, thanks to the supercomputer's calculations. By assembling a working virtual replica of protons and other subatomic particles such as D-mesons, the work opens up a completely new way of finding physics beyond the standard model, physicists' best theory about the particles and forces in nature. This promising approach is based on a theory called quantum chromodynamics (QCD) and it goes by the name of lattice QCD. It has enjoyed a reversal of fortune in the past few months after many years when it was considered a poor relation of particle physics. While experiments churned out particles whose behaviour shed light on the internal workings of the strong force, lattice QCD theorists were left playing catch-up.

That debate is all about the behaviour of the most fundamental particle: the quark. Quarks cluster together to create the protons and neutrons found in the nucleus of every atom, and ever since evidence for their existence was found by bouncing electrons off them in the 1960s, researchers thought they pretty much understood quarks. Last year, several groups of scientists reported finding something unusual in their particle accelerators. The full significance of the pentaquark was not immediately clear. Conventional quark theory, called quantum chromodynamics, describes quarks and the strong nuclear forces that hold them together.

Provides information on gluons, which are particles inside a proton that transmit the force that binds quarks together. Explanation of Frank Wilczek's theory of quantum chromodynamics; Advancements in particle physics during the early 1970s; Internal structure of a proton; Description of a particle-physics laboratory. INSET: WILL THEY KILL US ALL?.

Theoretical physicist and Nobel laureate How did competing in STS influence you? Asymptotic freedom, which I discovered with David J. Gross in the 1970s, is best understood in the context of what it accomplished for physics: It was the key to getting to the fundamental theory of what's called the strong force, which is the force responsible for holding together atomic nuclei. Using very sophisticated instruments and image processing, scientists were able to take a look inside protons and found that protons had an internal structure with smaller particles inside. [Extracted from the article]

Discusses efforts to release quarks, which are the centers of nuclear particles. Quark-gluon plasma; Quantum chromodynamics; Study of neutrons to find quarks; Efforts of Astrophysicists to come up with observational tests for quark matter in neutron stars; Information needed to find out if neutron stars harbor quark matter; Importance of the density of the core of a neutron; Efforts of investigators to pin down its place on the phase diagram.

Reports on experiments that are taking place on the crucial properties involved in the spin of protons and neutrons. The importance of spin; The problem with the theory that describes the strong force, known as quantum chromodynamics or QCD; The HERa MEasurement of nucleon Spin (HERMES) collaboration.

Abstract The program N2HDECAY calculates the branching ratios and decay widths of the Higgs bosons of the Next-to-Two-Higgs-Doublet Model (N2HDM). The code incorporates the dominant higher-order effects by including QCD corrections and off-shell decay modes. The N2HDM is an extension of the Standard Model by a Higgs doublet and a real Higgs singlet. Its phenomenology can change dramatically depending on which global symmetries are broken by electroweak symmetry breaking. It can feature a large visible Higgs sector in the broken phase, behave like a 2HDM with scalar singlet dark matter in the dark singlet phase, or, in the inert doublet phase, extend an inert doublet model by mixing a singlet with the SM Higgs boson. N2HDECAY provides precise predictions for the decays of the Higgs bosons in all of these phases. Program summary Program Title: N2HDECAY Program Files doi: http://dx.doi.org/10.17632/n45d9zd5xz.1 Licensing provisions: GPLv2 Programming language: Fortran 77 Nature of problem: Calculation of branching ratios and total widths for the Higgs bosons and the top-quark in the N2HDM. To achieve a high precision, the decay widths are calculated including all available QCD and off-shell corrections. Solution method: The code calculates all required Higgs couplings from a standard set of N2HDM input parameters. The computations of the decay widths use analytic formulas for all two particle final states. Off-shell decays are integrated numerically and a linear interpolation over the resonance is performed. [ABSTRACT FROM AUTHOR]

We study nonlinear waves in a nonrelativistic ideal and cold quark gluon plasma immersed in a strong uniform magnetic field. In the context of nonrelativistic hydrodynamics with an external magnetic field we derive a nonlinear wave equation for baryon density perturbations, which can be written as a reduced Ostrovsky equation. We find analytical solutions and identify the effects of the magnetic field. [ABSTRACT FROM AUTHOR]

We present a new release of the program iHixs . This easy-to-use tool allows to derive state of the art predictions for the inclusive production cross section of a Higgs boson at hadron colliders in the gluon fusion production mode. This includes the most up-to-date corrections in perturbative QCD and electro-weak theory, effects due to finite quark masses as well as an option to perform threshold resummation. In particular, exact perturbative QCD corrections through N 3 LO are included in the heavy top quark effective theory. Furthermore, iHixs contains automatic routines that allow to assess residual uncertainties on the prediction for the Higgs boson production cross section according to well established standard definitions. iHixs can be obtained from https://github.com/dulatf/ihixs . Program summary Program Title: iHixs Program Files doi: http://dx.doi.org/10.17632/84ww5n6yrm.1 Licensing provisions: MIT License Programming language: C++ External routines/libraries: Cuba, Chaplin (shipped with code) Nature of problem: Determine the inclusive Higgs boson cross section at hadron colliders in the gluon fusion production mode. Solution method: Numerical convolution of analytic partonic cross sections with parton distribution functions. [ABSTRACT FROM AUTHOR]

We describe a numerical calculation tool H-COUP 3 3 The webpage of H-COUP is given in http://www-het.phys.sci.osaka-u.ac.jp/~kanemu/HCOUP_HP1013/HCOUP_HP.html , where one can download the set of source files of H-COUP_1.0 . written in Fortran, which provides one-loop electroweak corrected vertices for the discovered Higgs boson h ( 125 ) in various Higgs sectors. The renormalization is based on the improved on-shell scheme without gauge dependence. In the first version H-COUP_1.0 , the following models are included, namely, the Higgs singlet model, four types (Type-I, Type-II, Type-X, Type-Y) of two Higgs doublet models with a softly-broken Z 2 symmetry and the inert doublet model. We first briefly introduce these models and then explain how to install and run this tool in an individual machine. A sample of numerical outputs is provided for user information. Program summary Program title : H-COUP Program Files doi : http://dx.doi.org/10.17632/f88szmrj5x.1 Licensing provisions : GPLv3 Programming language : Fortran90 Nature of problem : One-loop electroweak corrected vertices for the discovered Higgs boson h ( 125 ) are numerically calculated in the Higgs singlet model, four types (Type-I, Type-II, Type-X, Type-Y) of two Higgs doublet models with a softly-broken Z 2 symmetry and the inert doublet model. The renormalization is based on the improved on-shell scheme without gauge dependence. Loop induced decay rates, i.e., h → γ γ , h → Z γ and h → g g are also computed in these extended Higgs sectors at leading order. Solution method : All one-loop integrals for one-, two- and three-point functions are analytically expressed by using Passarino–Veltman functions in a systematic way, and their numerical values are calculated through the LoopTools. One-loop corrected h ( 125 ) vertices are then numerically provided in terms of form factors which are obtained by decomposing their Lorentz structure. Additional comments including restrictions and unusual features : In the version 1.0, QCD corrections are not included in the calculation of the h ( 125 ) vertices as well as the loop induced decay rates. In addition, the total width, decay branching ratios and cross sections are not outputted automatically. Details of these issues are described in Sec. VII of this manual. References: [1] S. Kanemura, Y. Okada, E. Senaha and C.-P. Yuan, Phys. Rev. D 70 , 115002 (2004) [hep-ph/0408364]. [2] S. Kanemura, M. Kikuchi and K. Yagyu, Phys. Lett. B 731 , 27 (2014) [ arXiv:1401.0515 [hep-ph]]. [3] S. Kanemura, M. Kikuchi and K. Yagyu, Nucl. Phys. B 896 , 80 (2015) [ arXiv:1502.07716 [hep-ph]]. [4] S. Kanemura, M. Kikuchi and K. Yagyu, Nucl. Phys. B 907 , 286 (2016) [ arXiv:1511.06211 [hep-ph]]. [5] S. Kanemura, M. Kikuchi and K. Sakurai, Phys. Rev. D 94 , no. 11, 115011 (2016) [ arXiv:1605.08520 [hep-ph]]. [6] S. Kanemura, M. Kikuchi and K. Yagyu, Nucl. Phys. B 917 , 154 (2017) [ arXiv:1608.01582 [hep-ph]]. [7] S. Kanemura, M. Kikuchi, K. Sakurai and K. Yagyu, Phys. Rev. D 96 , no. 3, 035014 (2017) [ arXiv:1705.05399 [hep-ph]]. [ABSTRACT FROM AUTHOR]

The cost of the iterative solution of a sparse matrix–vector system against multiple vectors is a common challenge within scientific computing. A tremendous number of algorithmic advances, such as eigenvector deflation and domain-specific multi-grid algorithms, have been ubiquitously beneficial in reducing this cost. However, they do not address the intrinsic memory-bandwidth constraints of the matrix–vector operation dominating iterative solvers. Batching this operation for multiple vectors and exploiting cache and register blocking can yield a super-linear speed up. Block-Krylov solvers can naturally take advantage of such batched matrix–vector operations, further reducing the iterations to solution by sharing the Krylov space between solves. Practical implementations typically suffer from the quadratic scaling in the number of vector–vector operations. We present an implementation of the block Conjugate Gradient algorithm on NVIDIA GPUs which reduces the memory-bandwidth complexity of vector–vector operations from quadratic to linear. As a representative case, we consider the domain of lattice quantum chromodynamics and present results for one of the fermion discretizations. Using the QUDA library as a framework, we demonstrate a 5 × speedup compared to highly-optimized independent Krylov solves on NVIDIA’s SaturnV cluster. [ABSTRACT FROM AUTHOR]

Discusses Satyendra Bose's contributions to quantum chromodynamics (QCD). Theory of the strong interaction; Bose's mathematical description of light quanta; Previous thinking on black body radiation; Max Planck's version of the radiation laws; Bose's treatment of photons as particles which have to be counted in a different way; Implications of Bose's work.

Discusses research proving and disproving the theory of quantum chromodynamics (QCD). Theory as the only serious contender in explaining the fourth known force of nature; Failure of expected matches in an attempt to compare reality with calculations of specific interactions based on QCD; Small disturbances in QCD; Problems of confinement.

Discusses the practice of some physicists in pretending space-time is a chessboard. Details about the theory called quantum chromodynamics (QCD), a theory born in the 1970s; The use of supercomputers and a mathematical trick; The idea to treat space-time as if it were really a grid of discrete points; The impact of the proliferation of gluons.

Focuses on gluons, the carriers of the strong force between the quarks that make up protons and neutrons. Overview of the theory of the strong force known as quantum chromodynamics (QCD); Usage of the computer technique known as lattice QCD in discovering the properties of glueballs; Method of glueball formation.

Reports on the use of GF11, a supercomputer, in the calculation aspect in the theory of quantum chromodynamics (QCD). Explanation of the behavior of matter such as atomic particles; Limitation of QCD; Quarks and the color field; Transformation of space into a lattice; Confirmation of the fundamental theory behind quarks. INSET: QCD by Monte Carlo, by D.H.W..

The article focuses on the theory of the existence of quarks. The author describes that quarks come in four "flavors" and each flavor is said to come in three "colors." He claims that there are reasons to believe that quarks exist though attempts to isolate them were unsuccessful. He adds that the concept of quarks helps explain many apparently unrelated theories.

The article reports on the scientific experiment on the existence of glueballs. The discovery of any new particle is significant in its own right.. Its positive identification would confirm one of the most important distinctions between quantum chromodynamics (QCD) its parent theory. The temporary identification of the pseudoscalar glueball is a success of the QCD that is not directly obtain from quantum electrodynamics. There is a continuing effort in search for new glueballs.

Numerical simulations of quantum chromodynamics (QCD) on a lattice require the frequent solution of linear systems of equations with large, sparse and typically ill-conditioned matrices. Algebraic multigrid methods are meanwhile the standard for these difficult solves. Although the linear systems at the coarsest level of the multigrid hierarchy are much smaller than the ones at the finest level, they can be severely ill-conditioned, thus affecting the scalability of the whole solver. In this paper, we investigate different novel ways to enhance the coarsest-level solver and demonstrate their potential using DD- α AMG, one of the publicly available algebraic multigrid solvers for lattice QCD. We do this for two lattice discretizations, namely clover-improved Wilson and twisted mass. For both the combination of two of the investigated enhancements, deflation and polynomial preconditioning, yield significant improvements in the regime of small mass parameters. In the clover-improved Wilson case we observe a significantly improved insensitivity of the solver to conditioning, and for twisted mass we are able to get rid of a somewhat artificial increase of the twisted mass parameter on the coarsest level used so far to make the coarsest level solves converge more rapidly. [ABSTRACT FROM AUTHOR]

We present the results of an effort to accelerate a Rational Hybrid Monte Carlo (RHMC) program for lattice quantum chromodynamics (QCD) simulation for 2 flavors of staggered fermions on multiple Kepler K20X GPUs distributed on different nodes of a Cray XC30. We do not use CUDA but adopt a higher level directive based programming approach using the OpenACC platform. The lattice QCD algorithm is known to be bandwidth bound; our timing results illustrate this clearly, and we discuss how this limits the parallelization gains. We achieve more than a factor three speed-up compared to the CPU only MPI program. [ABSTRACT FROM AUTHOR]

Information about the number of Feynman graphs for a given physical process in a given field theory is especially useful for confirming the result of a Feynman graph generator used in an automatic system of perturbative calculations. A method of counting the number of Feynman graphs with weight of symmetry factor was established based on zero-dimensional field theory, and was used in scalar theories and QED. In this article this method is generalized to more complicated models by direct calculation of generating functions on a computer algebra system. This method is applied to QCD with and without counter terms, where many higher order are being calculated automatically. [ABSTRACT FROM AUTHOR]

We describe an extension of the SOFTSUSY spectrum calculator to include two-loop supersymmetric QCD (SUSYQCD) corrections of order O ( α s 2 ) to gluino and squark pole masses, either in the minimal supersymmetric standard model (MSSM) or the next-to-minimal supersymmetric standard model (NMSSM). This document provides an overview of the program and acts as a manual for the new version of SOFTSUSY , which includes the increase in accuracy in squark and gluino pole mass predictions. Program summary Program title: SOFTSUSY Program Files doi: http://dx.doi.org/10.17632/sh77x9j7hs.1 Licensing provisions: GNU GPLv3 Programming language: C++ , fortran , C Nature of problem: Calculating supersymmetric particle spectrum, mixing parameters and couplings in the MSSM or the NMSSM. The solution to the renormalization group equations must be consistent with theoretical boundary conditions on supersymmetry breaking parameters, as well as a weak-scale boundary condition on gauge couplings, Yukawa couplings and the Higgs potential parameters. Solution method: Nested fixed point iteration. Restrictions: SOFTSUSY will provide a solution only in the perturbative regime and it assumes that all couplings of the model are real (i.e. C P − conserving). If the parameter point under investigation is non-physical for some reason (for example because the electroweak potential does not have an acceptable minimum), SOFTSUSY returns an error message. The higher order corrections included are for the MSSM ( R -parity conserving or violating) or the real R -parity conserving NMSSM only. Journal reference of previous version: Comput. Phys. Comm. 189 (2015) 192. Does the new version supersede the previous version?: Yes. Reasons for the new version: It is desirable to improve the accuracy of the squark and gluinos mass predictions, since they strongly affect supersymmetric particle production cross-sections at colliders. Summary of revisions: The calculation of the squark and gluino pole masses is extended to be of next-to-next-to leading order in SUSYQCD, i.e. including terms up to O ( g s 4 ∕ ( 16 π 2 ) 2 ) . Additional comments: Program obtainable from http://softsusy.hepforge.org/ [ABSTRACT FROM AUTHOR]

We consider the possibility of using reweighting techniques in order to correct the breaking of unitarity when twisted boundary conditions are imposed on valence fermions in simulations of lattice gauge theories. We start by studying the properties of reweighting factors and their variances at tree-level. This leads us to the introduction of a factorization for the fermionic reweighting determinant. In the numerical, stochastic implementation of the method, we find that the effect of reweighting is negligible in the case of large volumes but it is sizeable when the volumes are small and the twisting angles are large. More importantly, we find that for un-improved Wilson fermions, and in small volumes, the dependence of the critical quark mass on the twisting angle is quite pronounced and results in large violations of the continuum dispersion relation. [ABSTRACT FROM AUTHOR]

The article offers information regarding the identity of the subatomic particle known as the proton. It highlights nuclear physicist Evangeline Downie's research regarding the matter and also presents details on its composition. Topics discussed include its spin and death. The concept of quantum chromodynamics (QCD) with regard to the particle is also discussed.

Version 1.6.0 of the code SusHi is presented. Concerning inclusive CP-even Higgs production in gluon fusion, the following new features with respect to previous versions have been implemented: expansion of the partonic cross section in the soft limit, i.e. around x = M H 2 ∕ s ˆ → 1 ; N 3 LO QCD corrections in terms of the soft expansion; top-quark mass suppressed terms through NNLO; matching to the cross section at x → 0 through N 3 LO. For CP-even and -odd scalars, an efficient evaluation of the renormalization-scale dependence is included, and effects of dimension-5 operators can be studied, which we demonstrate for the SM Higgs boson and for a CP-even scalar with a mass of 750 GeV . In addition, as a generalization of the previously available b b ̄ → H cross section, SusHi_1.6.0 provides the cross section for charged and neutral Higgs production in the annihilation of arbitrary heavy quarks. At fixed order in perturbation theory, SusHi thus allows to obtain Higgs cross-section predictions in different models to the highest precision known today. For the SM Higgs boson of M H = 125 GeV , SusHi yields 48.28 pb for the gluon-fusion cross section at the LHC at 13 TeV . Simultaneously, SusHi provides the renormalization-scale uncertainty of ± 1 . 97 pb. New version program summary Program title: SusHi . Program Files doi: http://dx.doi.org/10.17632/3bb3z4k9hp.1 Licensing provisions: GNU General Public License 3 (GPL). Programming language: Fortran 77. Journal Reference of previous version: Comp. Phys. Comm. 184, Issue 6 (2013) 1605–1617 Does the new version supersede the previous version?: Yes. The new version also includes all features of previous versions. Reasons for the new version: Compared to version 1.0.0 the newest SusHi version 1.6.0 now supports the 2-Higgs-Doublet-Model (2HDM) and the next-to-minimal supersymmetric standard model (NMSSM). The effects of dimension-5 operators in the calculation of the gluon-fusion cross section can be studied. It allows to calculate the Higgs production cross section from the annihilation of heavy quarks and includes various new features which improve the gluon-fusion cross-section prediction and the associated uncertainty estimate. Links to external codes 2HDMC , MoRe-SusHi and MadGraph5_aMC@NLO can be established. Summary of revisions: Inclusion of 2HDM, NMSSM; Improvements in the prediction of the gluon-fusion cross section: Top-quark mass terms up to next-to-next-to leading order, soft expansion and next-to-next-to-next-to leading order corrections in the heavy top-quark effective theory, top squark corrections up to next-to-next-to leading order; dimension-5 operators; analytic determination of the renormalization scale dependence. Inclusion of heavy-quark annihilation cross sections. Link to MoRe-SusHi for the calculation of resummed transverse-momentum distributions. Nature of problem: Calculation of inclusive and exclusive Higgs production cross sections in gluon fusion and heavy-quark annihilation in the SM and extended Higgs sectors through next-to-leading order QCD, including (next-to-)next-to-next-to-leading order top-(s)quark contributions and electroweak effects. Solution method: Numerical Monte Carlo integration. References: http://sushi.hepforge.org [ABSTRACT FROM AUTHOR]

Observables in particle physics and specifically in lattice QCD calculations are often extracted from fits. Standard χ 2 tests require a reliable determination of the covariance matrix and its inverse from correlated and auto-correlated data, a challenging task often leading to close-to-singular estimates. These motivate modifications of the definition of χ 2 such as uncorrelated fits. We show how the goodness-of-fit measured by their p-value can still be estimated robustly for a broad class of such fits. [ABSTRACT FROM AUTHOR]

We describe the QQbar_threshold library for computing the production cross section of heavy quark–antiquark pairs near threshold at electron–positron colliders. The prediction includes all presently known QCD, electroweak, Higgs, and nonresonant corrections in the combined nonrelativistic and weak-coupling expansion. Program summary Program title: QQbar_threshold Program Files doi: http://dx.doi.org/10.17632/883wgrb86h.1 Licensing provisions: GNU GPLv3. Programming language: C++, Wolfram Language. External Routines: Boost ( http://www.boost.org ), GSL ( http://www.gnu.org/software/gsl/ ). Nature of problem: Precision predictions for the pair-production cross section near threshold are essential in order to determine the properties of heavy quarks. Solution method: Formulas for all known perturbative corrections are implemented, so that QQbar_threshold provides a state-of-the-art theory prediction. Restrictions: Non-perturbative effects are not accounted for. This limits the applicability in the case of bottom quarks and excludes all lighter quarks. Due to the nonrelativistic approximation predictions for the cross section are only reliable near threshold. Running time: Typically about 5 ms per parameter point. [ABSTRACT FROM AUTHOR]

The article focuses on the hypothetical bound states of gluons called glueballs. The existence of glueball is suggested by the theory of quantum chromodynamics (QCD) which has been successful in explaining the proliferation of particles found in experiments with accelerators. QCD is analogous in many ways to quantum electrodynamics (QED), which describes the quantum nature of electromagnetic interaction. The mediating particle in QED is the photon, which is massless and moves with the speed of light.

The article discusses the theory quantum chromodynamics or QCD. The theory is based on the idea of the quark which makes up hadrons. The theory is regarding how the quarks move inside a hadron and how they interact with one another and is formulated on the model of quantum elecrodynamics (QED). The QED is the modern theory of electromagnetic interactions. Details of the theory are presented.

To learn more about the mysteries of quantum chromodynamics, we are probing the universe's densest stars, writes Chanda Prescod-Weinstein [ABSTRACT FROM AUTHOR]

Keywords: Physics EN Physics 2023 FEB 5 (NewsRx) -- By a News Reporter-Staff News Editor at Medical Devices & Surgical Technology Week -- A new study on physics is now available. This article presents a systematic study of the correlators used experimentally to probe the CME by using the Anomalous Viscous Fluid Dynamics (AVFD) model in Pb-Pb and Xe-Xe collisions at sNN = 5.02 TeV and sNN = 5.44 TeV, respectively.". [Extracted from the article]

Reconstructing hadron spectral functions through Euclidean correlation functions are of the important missions in lattice QCD calculations. However, in a Källen–Lehmann (KL) spectral representation, the reconstruction is observed to be ill-posed in practice. It is usually ascribed to the fewer observation points compared to the number of points in the spectral function. In this paper, by solving the eigenvalue problem of continuous KL convolution, we show analytically that the ill-posedness of the inversion is fundamental and it exists even for continuous correlation functions. We discussed how to introduce regulators to alleviate the predicament, in which include the Artificial Neural Networks (ANNs) representations recently proposed by the Authors in [28]. The uniqueness of solutions using ANNs representations is manifested analytically and validated numerically. Reconstructed spectral functions using different regularization schemes are also demonstrated, together with their eigen-mode decomposition. We observe that components with large eigenvalues can be reliably reconstructed by all methods, whereas those with low eigenvalues need to be constrained by regulators. [ABSTRACT FROM AUTHOR]

A modern Fortran implementation of three Dirac operators (Wilson, Brillouin, Susskind) in lattice QCD is presented, based on OpenMP shared-memory parallelization and SIMD pragmas. The main idea is to apply a Dirac operator to N v vectors simultaneously, to ease the memory bandwidth bottleneck. All index computations are left to the compiler and maximum weight is given to portability and flexibility. The lattice volume, N x N y N z N t , the number of colors, N c , and the number of right-hand sides, N v , are parameters defined at compile time. Several memory layout options are compared. The code performs well on modern many-core architectures (480 Gflop/s, 880 Gflop/s, and 780 Gflop/s with N v = 12 for the three operators in single precision on a 72-core KNL processor, a 2 × 24 -core Skylake node yields similar results). Explicit run-time tests with CG/BiCGstab inverters confirm that the memory layout is relevant for the KNL, but less so for the Skylake architecture. The ancillary code distribution contains all routines, including the single, double, and mixed precision Krylov space solvers, to render it self-contained and ready-to-use. Program title: testknl_main.f90 CPC Library link to program files: https://doi.org/10.17632/7km9wcspn3.1 Licensing provisions: Creative Commons by 4.0 Programming language: fortran 2008 Supplementary material: Detailed description of each module of the code distribution. Nature of problem: Solving the Dirac equation D u = b for three choices of the Dirac operator D relevant to Lattice QCD. The choices are known as Wilson fermions, Brillouin fermions and Susskind or staggered fermions, respectively. Solution method: Standard solution through sparse iterative solvers CG and BiCGstab, albeit with several right-hand vectors packed into a right-hand matrix. The number of colors, N c , the number of right-hand sides, N v , and the box lengths, N x , N y , N z and N t , can be chosen freely. Additional comments including restrictions and unusual features: The code allows the user to compare several memory layout options for the block of right-hand sides, that is several orderings of the slots pertinent to N c , N v and possibly the Dirac spinor, in the array representation of u and b. No machine dependent optimizations are used, only standard OpenMP shared-memory parallelization and SIMD pragmas are used. [ABSTRACT FROM AUTHOR]

We present an algorithm to evaluate multiloop Feynman integrals with an arbitrary number of internal massive lines, with the masses being in general complex-valued, and its implementation in the Mathematica package SeaSyde. The implementation solves by series expansions the system of differential equations satisfied by the Master Integrals. At variance with respect to other existing codes, the analytical continuation of the solution is performed in the complex plane associated to each kinematical invariant. We present the results of the evaluation of the Master Integrals relevant for the NNLO QCD-EW corrections to the neutral-current Drell-Yan processes. Program Title: SeaSyde CPC Library link to program files: https://doi.org/10.17632/4hk9rbw4y8.1 Developer's repository link: https://github.com/TommasoArmadillo/SeaSyde Licensing provisions: GPLv3 Programming language: Mathematica Nature of problem: Solution of multi-loop Feynman integrals with an arbitrary number of internal complex-valued massive lines. Solution method:: Solution via series expansions of the systems of differential equations satisfied by the loop integrals. Analytic continuation of the solution to any point of the kinematic variables. The solution is transported from the initial to the final point, by moving in the complex plane associated to each kinematic variable. In multi-variable problems, the transport is computed one variable at the time. [ABSTRACT FROM AUTHOR]

We present results on the world's first over 100 PFLOPS single precision lattice QCD quark solver on the Japanese new supercomputer Fugaku. We achieve a factor 38 time speedup from the supercomputer K on the same problem size, 1924, with 102 PFLOPS, 10% floating-point operation efficiency against single precision floating-point operation peak. The evaluation region is the single precision BiCGStab for a Clover–Wilson Dirac matrix with Schwarz Alternating Procedure domain decomposition preconditioning using Jacobi iteration for the local domain matrix inversion. [ABSTRACT FROM AUTHOR]

We describe an approach for the efficient calculation of a large number of four-point correlation functions for various baryon–baryon ( B B ) channels, which are the primary quantities for studying the nuclear and hyperonic nuclear forces from lattice quantum chromodynamics. Using the four-point correlation function of a proton- Λ system as a specific example, we discuss how an effective block algorithm significantly reduces the number of iterations. The effective block algorithm is applied to calculate 52 channels of the four-point correlation functions from nucleon–nucleon to Ξ – Ξ , in order to study the complete set of isospin symmetric B B interactions. The elapsed times measured for hybrid parallel computation on BlueGene/Q demonstrate that the performance of the present algorithm is reasonable for various combinations of the number of OpenMP threads and the number of MPI nodes. The numerical results are compared with the results obtained using the unified contraction algorithm for all computed sites of the 52 four-point correlators. [ABSTRACT FROM AUTHOR]

We present the C++ program library mr that allows us to reliably calculate the values of the running parameters in the Standard Model at high energy scales. The initial conditions are obtained by relating the running parameters in the MS ¯ renormalization scheme to observables at lower energies with full two-loop precision. The evolution is then performed in accordance with the renormalization group equations with full three-loop precision. Pure QCD corrections to the matching and running are included through four loops. We also provide a Mathematica interface for this program library. Program summary Program title: mr Catalogue identifier: AFAI_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AFAI_v1_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: GNU General Public License, version 3 No. of lines in distributed program, including test data, etc.: 517613 No. of bytes in distributed program, including test data, etc.: 2358729 Distribution format: tar.gz Programming language: C++. Computer: IBM PC. Operating system: Linux, Mac OS X. RAM: 1 GB Classification: 11.1. External routines: TSIL [1], OdeInt [2], boost [3] Nature of problem: The running parameters of the Standard Model renormalized in the MS ¯ scheme at some high renormalization scale, which is chosen by the user, are evaluated in perturbation theory as precisely as possible in two steps. First, the initial conditions at the electroweak energy scale are evaluated from the Fermi constant G F and the pole masses of the W, Z, and Higgs bosons and the bottom and top quarks including the full two-loop threshold corrections. Second, the evolution to the high energy scale is performed by numerically solving the renormalization group evolution equations through three loops. Pure QCD corrections to the matching and running are included through four loops. Solution method: Numerical integration of analytic expressions Additional comments: Available for download from URL: http://apik.github.io/mr/ . The MathLink interface is tested to work with Mathematica 7–9 and, with an additional flag, also with Mathematica 10 under Linux and with Mathematica 10 under Mac OS X. Running time: less than 1 second References: [1] S. P. Martin and D. G. Robertson, Comput. Phys. Commun. 174 (2006) 133–151 [ hep-ph/0501132 ]. [2] K. Ahnert and M. Mulansky, AIP Conf. Proc. 1389 (2011) 1586–1589 [ arxiv:1110.3397 [cs.MS]]. [3] http://www.boost.org/ [ABSTRACT FROM AUTHOR]

We discuss the usage and applicability of deflation methods for the overlap lattice Dirac operator, focusing on calculating the eigenvalues using a method similar to the eigCG algorithm used for other Dirac operators. The overlap operator, which contains several theoretical advantages over other formulations of lattice Quantum Chromodynamics, is more computationally expensive because it requires the computation of the matrix sign function. The principal change made compared to deflation methods for other formulations of lattice QCD is that it is necessary for best performance to tune the accuracy of the matrix sign function as the computation proceeds. We present two possible relaxation strategies, one which provides a rigorous bound for the eigenvalues but seems to be too conservative in practice, and a second which is less conservative but, while its stability is not guaranteed, seems to work well in practice. We adapt the original eigCG algorithm for two of the preferred inversion algorithms for overlap fermions, GMRESR(relCG) and GMRESR(relSUMR). Before deflation, the rate of convergence of these routines in terms of iterations is similar, but, since the Shifted Unitary Minimal Residual (SUMR) algorithm only requires one call to the matrix sign function compared to the two calls required for Conjugate Gradient (CG), SUMR is usually preferred for single inversions of the Dirac operator. We construct bounds for the required accuracy of the matrix sign function during the eigenvalue calculation. For the SUMR algorithm, we use a variant of the Galerkin projection to perform the deflation; while for the CG algorithm, we are able to use a considerably superior spectral pre-conditioner. The superior performance of the spectral pre-conditioner, and its need for less accurate eigenvalues, almost erodes SUMR’s advantage over CG as an inversion algorithm. We see factor of three gains for the inversion algorithm from the deflation on our small test lattices; we expect larger gains over the undeflated algorithms in realistic simulations on larger lattices and with smaller masses. There is, however, a significant cost in the eigenvalue calculation because we cannot relax the accuracy of the matrix sign function as aggressively when calculating the eigenvalues as we do while performing the inversions. This set-up cost is, however, more than compensated for the gain in the deflation if enough right hand sides are required. [ABSTRACT FROM AUTHOR]

We introduce the recently developed IR-improved DGLAP-CS theory into the showers in Pythia8, as this Monte Carlo event generator is in wide use at LHC. We show that, just as it was true in the IR-improved shower Monte Carlo Herwiri, which realizes the IR-improved DGLAP-CS theory in the Herwig6.5 environment, the soft limit in processes such as single heavy gauge boson production is now more physical in the IR-improved DGLAP-CS theory version of Pythia8. This opens the way to one’s getting a comparison between the actual detector simulations for some of the LHC experiments between IR-improved and unimproved showers as Pythia8 is used in detector simulations at LHC whereas Herwig6.5, the environment of the only other IR-improved DGLAP-CS QCD MC in the literature, Herwiri1.031, is not any longer so used. Our achieving the availability of the IR-improved DGLAP-CS Pythia8 then is an important step in the further development of the LHC precision theory program under development by the author and his collaborators. [ABSTRACT FROM AUTHOR]