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Dr
Hyung-Jin Kim
(Brookhaven National Laboratory)
24/06/2014, 18:10
Hadron Spectroscopy and Interactions
Poster
The $\eta-\eta'$ mass splitting coming from anomalous effect on U(1) axial currents has been a historical issue.
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The QCD gauge field topology with instanton can explain this problem and show consistent result with experimental mass of $\eta'$.
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Based on the $2+1$ flavor lattice QCD simulation, previous $\eta-\eta'$ masses study shows about 15\% level of accuracy.
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With the advanced...
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Valentina Verduci
(University of Graz)
24/06/2014, 18:10
Hadron Spectroscopy and Interactions
Poster
In recent years the study of two particle systems on the lattice has led to excellent results in the meson sector of the QCD spectrum, however baryon resonances remain mostly unexplored.
We present an initial study of pion-nucleon systems as decay product of baryon resonances in different channels. The final goal is to extract the resonance parameters from the correlation functions of...
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Mr
Jaehoon Leem
(Seoul National University)
24/06/2014, 18:10
Weak Decays and Matrix Elements
Poster
We present results of the Kaon B-parameters calculated using the HYP-improved staggered quarks on the MILC asqtad lattices.
The perturbative matching is done at one-loop level.
We extrapolate the data to physical pion mass using the SU(2) staggered chiral perturbation theory.
After that, we simultaneously extrapolate results to the continuum (a = 0) and physical sea quark mass.
We...
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Mr
Alessandro Sciarra
(Goethe University, Frankfurt am Main), Mr
Christopher Pinke
(Institute for Theoretical Physics, Goethe-University Frankfurt am Main)
24/06/2014, 18:10
Algorithms and Machines
Poster
In recent years it has been shown that Lattice QCD (LQCD) can benefit
enormously from Graphic Processing Units (GPUs), which are well suited
for memory bandwidth limited applications. Accordingly, the usage of
GPUs in LQCD simulations is still expanding,
mainly relying on CUDA, applicable to NVIDIA hardware only. A hardware
vendor independent approach is given by the Open Computing...
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Mr
Alessandro Sciarra
(Goethe University, Frankfurt am Main), Mr
Christopher Pinke
(Institute for Theoretical Physics, Goethe-University Frankfurt am Main)
24/06/2014, 18:10
Algorithms and Machines
Poster
In recent years it has been shown that Lattice QCD (LQCD) can benefit enormously from Graphic Processing Units (GPUs), which are well suited for memory bandwidth limited applications. Accordingly, the usage of GPUs in LQCD simulations is still expanding,
mainly relying on CUDA, applicable to NVIDIA hardware only. A hardware vendor independent approach is given by the Open Computing Language...
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Yusuke Namekawa
(University of Tsukuba)
24/06/2014, 18:10
Vacuum Structure and Confinement
Poster
Comparative study of topological charge is performed.
Topological charges are measured by a cloverleaf operator
on smoothed gauge configurations.
Various types of smoothing techniques are employed.
We investigate
to what extent each smoothing makes the topological charge an integer.
Consistency of the topological charge in the fermionic definition
is also examined.
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Mr
Alexander Schmidt
(Phd)
24/06/2014, 18:10
Nonzero Temperature and Density
Poster
We explore two flavor scalar electrodynamics on the lattice, which has a complex phase problem at finite chemical potential. By rewriting the action in terms of dual variables this complex phase problem can be solved exactly. The dual variables are link- and plaquette occupation numbers, subject to local constraints that have to be respected by the Monte Carlo
algorithm. For the simulation we...
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Dr
Enrico Rinaldi
(Physics Division, Lawrence Livermore National Laboratory),
Yasumichi Aoki
(Nagoya University)
24/06/2014, 18:10
The spectrum of twelve-flavor QCD has been studied in details by the LatKMI collaboration. Here we present our updated results obtained with the HISQ action at two lattice spacings, several volumes and fermion masses. We emphasize the existence of a flavor-singlet scalar state parametrically light with respect to the rest of the spectrum, first reported in our paper [1]. This feature is...
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Mr
Arjun Gambhir
(College of William and Mary)
24/06/2014, 18:10
Algorithms and Machines
Poster
Reverse Monte Carlo, by Mak and Sharma, is a technique that allows for stochastic modification of the action of a lattice theory, while respecting the detailed balance condition of the original action. This modification of the action may permit more efficient
evolution of modes with large autocorrelation times. The classic
Swendsen and Wang cluster algorithm for the Ising model is in fact...
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Mr
Johannes Heinrich Weber
(Technische Universität München)
24/06/2014, 18:10
The explicit breaking of time-reflection symmetry in the Karsten-Wilczek action is hidden in various mesonic correlation functions that are calculated in the quenched approximation. Two underlying discrete product symmetries are discussed, which each allow for enforcement of time-reflection symmetry for correlation functions constructed according to additional symmetry requirements.
An...
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Alessandro Papa
(Universita` della Calabria & INFN-Cosenza)
24/06/2014, 18:10
Theoretical Developments
Poster
Three-dimensional Z(N) lattice gauge theories are studied numerically
at finite temperature for N = 5, 6, 8, 12, 13, 20 and for N_t=2,4,8.
For each model the location of phase transitions and their critical
indices are determined. The scaling of critical points with N is proposed.
The data obtained enable us to verify the scaling near the continuum limit
for the Z(N) models at finite temperatures.
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Prof.
Weonjong Lee
(Seoul National University)
24/06/2014, 18:10
Weak Decays and Matrix Elements
Poster
We present results of $\varepsilon_K$, the indirect CP
violation parameter calculated on the lattice combined with various
inputs from the experiments. In this analysis we use the lattice
results of $B_K$ and $V_{cb}$ for the exclusive channel. In addition,
we also use Wolfenstein parameters from the CKM fitters and UT
fitters. We find 3.4(3) $\sigma$ difference in the exclusive...
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Dr
Etsuko Itou
(KEK, Japan)
24/06/2014, 18:10
Physics Beyond the Standard Model
Poster
We show the numerical simulation result for the mass anomalous dimension of the SU(3) gauge theory coupled to Nf = 12 fundamental fermions.
We use both the step scaling method and the hyperscaling for the Dirac eigenmode to determine the anomalous dimension in the vicinity of the infrared fixed point of the theory.
The continuum extrapolation is carefully taken in both analyses.
We also...
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Christof Gattringer
(Univ. Graz)
24/06/2014, 18:10
Nonzero Temperature and Density
Poster
Using hopping expansion techniques we discuss a partial mapping of finite density lattice QCD to dual variables. After truncation the partition sum has only real and positive contributions also at arbitrary chemical potential, and a Monte Carlo simulation is possible. We discuss the algebraic aspects of the dualization and show some first numerical results.
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Dr
Eigo Shintani
(Mainz University)
24/06/2014, 18:10
Hadron Spectroscopy and Interactions
Poster
We report preliminary result of all-mode-averaging technique in
Wilson fermion. On two-flavor CLS configurations, we compare the
performance to obtain high precision of nucleon form factor and
hadronic vacuum polarization function using truncated solver with deflated
SAP+GCR algorithm.
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Prof.
Attilio Cucchieri
(University of Sao Paulo)
24/06/2014, 18:10
Vacuum Structure and Confinement
Poster
By evaluating the so-called Bose-ghost propagator, we present the
first numerical evidence of BRST-symmetry breaking in minimal Landau
gauge, i.e. due to the restriction of the functional integration to
the first Gribov region in the Gribov-Zwanziger approach. We find
that our data are well described by a simple fitting function, which
can be related to a massive gluon propagator in...
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Jack Laiho
(Syracuse University)
24/06/2014, 18:10
I present the results of a study of Euclidean dynamical triangulations (EDT) in an attempt to formulate a theory of quantum gravity and to make contact with Weinberg's asymptotic safety scenario. There are two unphysical phases appearing in EDT, neither of which resembles semiclassical gravity. When the phase diagram is enlarged by including a nontrivial measure term a new region of the...
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Zechariah Gelzer
(University of Iowa)
24/06/2014, 18:10
Physics Beyond the Standard Model
Poster
We are studying the SU(3) gauge theory with 12 staggered fermions, searching for the endpoint of the line of first-order phase transitions in the mass-beta plane. This endpoint plays an important role in our understanding of the phase diagram of this model. Having found this endpoint with high statistics on a small lattice using unimproved staggered fermions, we are working to find it on...
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Dr
Konstantin Ottnad
(University of Cyprus)
24/06/2014, 18:10
The extraction of the magnetic form factor of the nucleon at zero momentum transfer is usually performed by adopting a parametrization for its momentum dependence and fitting the results obtained at finite momenta. We present methods that rely on taking the derivative of relevant correlators to extract directly the magnetic form factor at zero momentum without the need to assume a functional...
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Mr
Pranjal Vachaspati
(MIT)
24/06/2014, 18:10
Algorithms and Machines
Poster
In recent work, it has been shown that contractions for multi-nucleon systems can be cast in terms of weighted sums of determinants of matrices constructed from quark propagators. For typical correlation functions even for few nucleon systems, the number of such determinants can be very large depending on the complexity of the interpolating fields that are used. We investigate efficient...
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Prof.
Shailesh Chandrasekharan
(Duke University)
24/06/2014, 18:10
Theoretical Developments
Poster
Recent developments have shown that the fermion bag approach is a powerful method to solve fermion lattice field theories using Monte Carlo methods. Some sign problems that had remained unsolved earlier can now be solved within this approach. In this work we argue that the fermion bag approach also gives new insight into the mechanism of fermion mass generation. We discuss how chiral...
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andre walker-loud
(W&M)
24/06/2014, 18:10
Algorithms and Machines
Poster
Practitioners of lattice quantum chromodynamics (LQCD) have been some of the primary pioneer users of the state-of-the-art HPC systems, and contribute towards the stress tests of such new machines as soon as they become available. As with all aspects of HPC, I/O is becoming an increasingly specialized component of these systems. In order to take advantage of the latest available...
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Swagato Mukherjee
(BNL)
24/06/2014, 18:10
Algorithms and Machines
Poster
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amarjit soni
(BNL)
24/06/2014, 18:10
Hadron Spectroscopy and Interactions
Poster
We report our recent study of proton and neutron decay matrix element
with highly improved statistics using all-mode-averaging technique.
On 2+1 flavor domain-wall fermion configurations, we obtain accurate
proton to pseudoscalar (pion, K and eta) meson transition form factor.
In this report we also discuss the comparison with baryon chiral perturbation
in physical kinematics and estimate...
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Dr
Thomas Primer
(University of Arizona)
24/06/2014, 18:10
Weak Decays and Matrix Elements
Poster
We present calculations of the $K\to\pi,l\nu$ and $D\to\pi,l\nu$ semileptonic form factors at $q^2=0$.
These form factors are important for the determination of the CKM matrix elements $\lvert{V_{us}}\rvert$ and $\lvert{V_{cd}}\rvert$ respectively.
This work uses the HISQ action for both valence quarks and sea quarks on MILC $N_f=2+1+1$ configurations.
We employ twisted boundary conditions...
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Dr
Siwei Qiu
(National Institute of Health)
24/06/2014, 18:10
Theoretical Developments
Poster
Neurophysics is a relatively new science. We will use quantum field theory to analyze the neural network of theta model. With a special lattice, one can explore the short term memory using lattice field theory calculation. Here we will theoretically show the path integral formalism which can be used to do perturbation theory. Simple lattice simulation will be conducted to compare with the...
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Dr
Satoru Ueda
(KEK)
24/06/2014, 18:10
Algorithms and Machines
Poster
We are developing a new code set ``Bridge++'' for lattice simulations.
It is aimed to be an extensible, readable, and portable workbench,
while it keeps a high performance. Bridge++ covers conventional
lattice actions and numerical algorithms. A recent massively parallel
cluster system requires a hybrid parallel programing, such as MPI and
OpenMP. We also need elaborated programing...
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Dr
Marcus Petschlies
(Cyprus Institute / CaSToRC)
24/06/2014, 18:10
We present our results for the electron, the muon, and the tau anomalous magnetic moments obtained with four dynamical quarks.
Performing the continuum limit and an analysis of systematic effects, full agreement with phenomenological results is seen.
Additionally, the light quark contributions on the four-flavour sea are compared to the values obtained for N_f=2
physically light quarks. In...
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Dr
Frank Winter
(Thomas Jefferson National Accelerator Facility)
24/06/2014, 18:10
Algorithms and Machines
Poster
The Low Level Virtual Machine (LLVM) compiler infrastructure is a
promising platform for development of code that features performance
portability across a wide variety of architectures. It's widely
embraced by HPC industry and academia and high performance code
generating backends are available and supported for many relevant
architectures such as CUDA, X86-64, PowerPC64 including...
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Mr
Sourav Mondal
(Indian Association for the Cultivation of Science)
24/06/2014, 18:10
Algorithms and Machines
Poster
Following the multilevel scheme we present an error reduction algorithm for extracting glueball masses from monte-carlo simulations of pure SU(3)
lattice gauge theory. We look at the two lightest states viz. the 0^{++}
and 2^{++}. Our method involves looking at correlations between large wilson loops and does not require any smearing of links. The error bars we obtain are at the moment...
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Prof.
Christine Davies
(University of Glasgow)
24/06/2014, 18:10
Weak Decays and Matrix Elements
Poster
HPQCD Collaboration: We will present the first lattice QCD calculation of the mixing parameters f_B\sqrt(B_B) and f_B_s\sqrt(B_B_s) for physical light quark masses. We use 2+1+1 MILC configurations at 3 values of the lattice spacing and with three u/d quark masses going down to the physical value. We use improved NRQCD for the b quarks.
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Michael Wagman
(University of Washington)
24/06/2014, 18:10
Standard Model Parameters and Renormalization
Poster
Neutron-antineutron oscillation is a baryon number violating process that is predicted to occur in many theories of physics beyond the standard model. To make quantitative predictions that can be compared to experiment, matrix elements of six-quark effective operators must be computed via lattice QCD and must also be connected to continuum beyond the standard model operators. We present...
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Dr
Alexander Rothkopf
(Institute for Theoretical Physics, Heidelberg University, Heidelberg, Germany), Dr
Peter Petreczky
(Brookhaven National Laboratory - Department of Physics, Upton, USA)
24/06/2014, 18:10
Nonzero Temperature and Density
Poster
We present the results of a recent study on the in-medium modification of the spectral properties of Bottomonium S-wave (\Upsilon) and P-wave (\chi_b) states. The medium degrees of freedom are represented by 48^3x12 HotQCD lattices with Nf=2+1 light HISQ flavors, which span the temperature range 140.40(MeV)(= 0.911T_C) < T < 248.63(MeV)(= 1.614T_C). The heavy quarks on the other hand are...
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Dr
Piotr Korcyl
(DESY Zeuthen)
24/06/2014, 18:10
Physics Beyond the Standard Model
Poster
We report on our non-perturbative investigations of Supersymmetric Yang-Mills Quantum Mechanics with four supercharges. We employed two independent numerical methods. As a first method we used the cut Fock space approach in which one constructs the Hamiltonian matrix in an approximated basis of the Hilbert space and diagonalize it numerically to obtain the energy spectrum. As a second method...
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Mr
Jeonghwan Pak
(Seoul National University)
24/06/2014, 18:10
Algorithms and Machines
Poster
There are new NVIDIA technologies, such as direct parallelism and GPU Direct, which reduce the communication time between GPUs and CPUs. NVIDIA Kepler GPUs also provide new features to improve the memory usage of CUDA codes which allows better performance in memory access, memory allocation, and deallocation. We optimize our conjugate gradient code for staggered quarks to obtain the full...
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Dr
Markus Pak
(University of Graz)
24/06/2014, 18:10
Vacuum Structure and Confinement
Poster
The chirally symmetric Overlap quark propagator is explored for the first time in Coulomb gauge. This gauge is well suited for studying the relation between confinement and chiral symmetry breaking. The dressing functions of the quark propagator and the dynamical mass function are evaluated. Chiral symmetry is then artificially restored by removing the low eigenmodes from the Dirac operator....
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Dr
Michael Creutz
(Physics Department, BNL)
24/06/2014, 18:10
Partially quenched chiral perturbation theory usually assumes that
valence quarks propagating on gauge configurations prepared with sea
quarks of different masses will form a chiral condensate as the
valence quark mass goes to zero. I present a counterexample involving
non-degenerate sea quarks where the valence condensate does not form.
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Mr
Marios Costa
(University of Cyprus)
24/06/2014, 18:10
Standard Model Parameters and Renormalization
Poster
The chromomagnetic operator mixes with a large number of operators under renormalization. We identify which operators can mix with the chromomagnetic operator, at the quantum level. Even in dimensional regularization (DR), which has the simplest mixing pattern, the chromomagnetic operator mixes with a total of 9 other operators,forming a basis of dimension-five (d=5), Lorentz scalar operators...
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Mr
Alessandro Amato
(Swansea University)
24/06/2014, 18:10
Nonzero Temperature and Density
Poster
The properties of the ground state of two-color QCD at non-zero baryon chemical potential mu present an interesting problem in strongly-interacting gauge theory; in particular the nature of the physically-relevant degrees of freedom in the superfluid phase
in the high-mu regime still needs clarification. In this study we present evidence for in-medium effects at high mu by studying the wave...
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Dr
Shinji Ejiri
(Niigata University)
24/06/2014, 18:10
Nonzero Temperature and Density
Poster
We investigate the phase transitions of (2+Nf)-flavor QCD, where two light flavors and Nf massive flavors exist, to discuss the electroweak baryogenesis in realistic technicolor scenario. Because an appearance of a first order phase transition at finite temperature is a necessary condition for the baryogenesis, it is important to study the nature of phase transition in the case of massless 2...
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Dr
Christopher Monahan
(College of William and Mary),
Kostas Orginos
(College of William and Mary / JLab)
24/06/2014, 18:10
Lattice QCD calculations of parton distribution functions have so far been restricted
to only their first few Melin moments. Broken rotational symmetry on the lattice introduces unavoidable power divergent mixing of lattice twist-2 matrix elements of different spin that obscures the continuum limit. Here I discuss new options that either avoid power divergent mixing or allow us to perform...
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Ms
Olga Larina
(Institute of Theoretical and Experimental Physics)
24/06/2014, 18:10
Hadron Spectroscopy and Interactions
Poster
We calculated correlators of vector and pseudoscalar currents in external strong abelian magnetic field in SU(3) gluodynamics.
The masses of charged and neutral mesons with various spins were calculated. We found out that the masses of mesons with zero spin s=0 decreased in increasing magnetic field, but the masses of Rho mesons with nonzero spin increased in the field.
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Mr
Thomas Kloiber
(University of Graz)
24/06/2014, 18:10
Vacuum Structure and Confinement
Poster
We study the effect of the theta angle in two dimensional scalar QED. Since the theta term is purely imaginary, it introduces a complex action problem which prevents conventional numerical simulations at non-zero values of theta. This problem is solved by mapping the model to a dual representation, which is real and non-negative, hence suitable for Monte Carlo simulations. We present technical...
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Oliver Witzel
(Boston University)
24/06/2014, 18:10
Physics Beyond the Standard Model
Poster
In order to study the transition from conformal to confining behavior of an SU(3) gauge theory, we present the novel idea to simulate a theory with four light and eight heavy flavors. Varying the mass of the heavy flavors, the theory changes from conformal to confining allowing us to demonstrate the walking nature of the running coupling as a function of the mass of the eight heavier flavors.
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Dr
Matthew Wingate
(DAMTP, University of Cambridge)
24/06/2014, 18:10
Weak Decays and Matrix Elements
Poster
This poster reviews our recent calculation of $B \to K^*$, $B_s \to \phi$, and
$B_s \to K^*$ form factors using nonrelativistic heavy quarks and improved
staggered quarks on MILC lattices. These unquenched calculations, performed
in the low-recoil kinematic regime, provide a significant improvement over the
use of extrapolated light cone sum rule results. We use the form factors
along...
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Dr
Ydalia Delgado Mercado
(University of Graz)
24/06/2014, 18:10
Nonzero Temperature and Density
Poster
We use the density of states method to compute the observables of the effective center model of QCD at finite density (where the system suffers from a complex phase problem). The density of states method is a reweighting method based on an improved evaluation of histograms for the distribution of states. We test this approach against the results from the dual simulations of the model, where...
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Prof.
Carleton DeTar
(University of Utah)
24/06/2014, 18:10
Hadron Spectroscopy and Interactions
Poster
We present preliminary simulation results for the I = 0 charmonium state X(3872)(1++) and the I = 1 charmonium state Zc(3900)(1+-). The study is performed on (2+1+1)-flavor highly improved staggered quark (HISQ) lattices with clover (Fermilab interpretation) charm quarks and HISQ light quarks. Since the X(3872) lies very close to the open charm D-bar-D* threshold, we use a combination of...
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Alexei Bazavov
(University of California/University of Iowa)
24/06/2014, 18:10
Applications Beyond QCD
Poster
We study the U(1)-Higgs model in two dimensions in the strongly coupled regime. The goal is to generate an effective theory where link variables are integrated out, producing 4-field operators. This theory can be matched with the second-order perturbation theory effective Hamiltonian for the Bose-Hubbard model. Such correspondence can then be exploited for building a lattice gauge theory...
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Prof.
Gernot Münster
(University of Muenster)
24/06/2014, 18:10
Theoretical Developments
Poster
In Monte Carlo simulations of $\mathcal{N}=1$ supersymmetric Yang-Mills theory the mass of the unphysical adjoint pion, which is easily obtained numerically, is being used for the tuning to the limit of vanishing gluino mass. We show how to define the adjoint pion in the framework of partially quenched chiral perturbation theory and we derive a relation between its mass and the mass of the...
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Ion-Olimpiu Stamatescu
(Inst. Theor. Physik, Universitaet Heidelberg)
24/06/2014, 18:10
Nonzero Temperature and Density
Poster
We use the heavy dense approximation of QCD (HD-QCD) at
next-to-leading order (NLO) in the hopping expansion, keeping the
full Yang-Mills action. We perform simulations at low temperatures,
in the region below 1/3 T_c(\mu=0), and at large \mu, \mu/T above 5.
We analyse the structure in the baryonic density and other quantities
at the onset. We present data from reweighting (RW) and...
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Dr
Björn Leder
(University of Wuppertal)
24/06/2014, 18:10
Algorithms and Machines
Poster
Quark mass reweighting can be used to tune the mass of dynamical quarks. The basic idea is to use gauge field ensembles generated at some bare mass parameters to evaluate observables at different bare sea quark masses. This involves the computation of so called reweighing factors which are given as ratios of fermion determinants. In the case of simulations including the strange quark,...
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