Publications (72)
The Present and Future of QCD
P. Achenbach, D. Adhikari, A. Afanasev +400
This White Paper presents the community inputs and scientific conclusions from the Hot and Cold QCD Town Meeting that took place September 23-25, 2022 at MIT, as part of the Nuclea…
Nucleon Structure using lattice QCD
C. Alexandrou, M. Constantinou, V. Drach +6
A review of recent nucleon structure calculations within lattice QCD is presented. The nucleon excited states, the axial charge, the isovector momentum fraction and helicity distri…
Nucleon electromagnetic form factors in twisted mass lattice QCD
C. Alexandrou, M. Brinet, J. Carbonell +6
We present results on the nucleon electromagnetic form factors within lattice QCD using two flavors of degenerate twisted mass fermions. Volume effects are examined using simulatio…
Perturbative Renormalization of Wilson line operators
M. Constantinou, H. Panagopoulos
We present results for the renormalization of gauge invariant nonlocal fermion operators which contain a Wilson line, to one loop level in lattice perturbation theory. Our calculat…
The chromomagnetic operator on the lattice
M. Constantinou, M. Costa, R. Frezzotti +5
We present our study of the renormalization of the chromomagnetic operator,O(CM), which appears in the effective Hamiltonian describing Delta S = 1 transitions in and beyond the St…
First Physics Results at the Physical Pion Mass from Wilson Twisted Mass Fermions at Maximal Twist
ETM Collaboration, A. Abdel-Rehim, C. Alexandrou +20
We present physics results from simulations of QCD using dynamical Wilson twisted mass fermions at the physical value of the pion mass. These simulations were enabled by…
Charge radii of the nucleon from its flavor dependent Dirac form factors
H. Atac, M. Constantinou, Z. -E. Meziani +2
We have determined the proton and the neutron charge radii from a global analysis of the proton and the neutron elastic form factors, after first performing a flavor decomposition…
Nucleon axial and pseudoscalar form factors from lattice QCD at the physical point
C. Alexandrou, S. Bacchio, M. Constantinou +8
We compute the nucleon axial and induced pseudoscalar form factors using three ensembles of gauge configurations, generated with dynamical light quarks with mass tuned to approxima…
Moments of nucleon generalized parton distributions from lattice QCD simulations at physical pion mass
C. Alexandrou, S. Bacchio, M. Constantinou +9
We present results for the moments of nucleon isovector vector and axial generalised parton distribution functions computed within lattice QCD. Three ensembles of maximally twisted…
K -> pi matrix elements of the chromagnetic operator on the lattice
M. Constantinou, M. Costa, R. Frezzotti +5
We present preliminary results of the first lattice QCD calculation of the K -> pi matrix elements of the chromomagnetic operator O_{CM}=g sbar sigma_{munu} G_{munu} d, which appea…
Disconnected quark loop contributions to nucleon observables in lattice QCD
A. Abdel-Rehim, C. Alexandrou, M. Constantinou +5
We perform a high statistics calculation of disconnected fermion loops on Graphics Processing Units for a range of nucleon matrix elements extracted using lattice QCD. The isoscala…
Complete flavor decomposition of the spin and momentum fraction of the proton using lattice QCD simulations at physical pion mass
C. Alexandrou, S. Bacchio, M. Constantinou +6
We evaluate the gluon and quark contributions to the spin of the proton using an ensemble of gauge configuration generated at physical pion mass. We compute all valence and sea qua…
Nucleon strange electromagnetic form factors
C. Alexandrou, S. Bacchio, M. Constantinou +4
The role of the strange quarks on the low-energy interactions of the proton can be probed through the strange electromagnetic form factors. Knowledge of these form factors provides…
Nucleon generalized form factors with twisted mass fermions
C. Alexandrou, M. Constantinou, V. Drach +3
We present results on the nucleon form factors, momentum fraction and helicity moment for and twisted mass fermions for a number of lattice volumes and lattice…
Quark masses using twisted mass fermion gauge ensembles
C. Alexandrou, S. Bacchio, G. Bergner +24
We present a calculation of the up, down, strange and charm quark masses performed within the lattice QCD framework. We use the twisted mass fermion action and carry out simulation…
Perturbative renormalization of staggered fermion operators with stout improvement: Application to the magnetic susceptibility of QCD
G. S. Bali, F. Bruckmann, M. Constantinou +5
We calculate the fermion propagator and the quark-antiquark Green's functions for a complete set of ultralocal fermion bilinears, [: scalar (S), pseudoscalar (P…
Nucleon axial, tensor and scalar charges and -terms in lattice QCD
C. Alexandrou, S. Bacchio, M. Constantinou +4
We determine the nucleon axial, scalar and tensor charges within lattice Quantum Chromodynamics including all contributions from valence and sea quarks. We analyze three gauge ense…
Evaluation of disconnected quark loops for hadron structure using GPUs
C. Alexandrou, M. Constantinou, V. Drach +5
A number of stochastic methods developed for the calculation of fermion loops are investigated and compared, in particular with respect to their efficiency when implemented on Grap…
Strange nucleon electromagnetic form factors from lattice QCD
C. Alexandrou, M. Constantinou, K. Hadjiyiannakou +4
We evaluate the strange nucleon electromagnetic form factors using an ensemble of gauge configurations generated with two degenerate maximally twisted mass clover-improved fermions…
2-loop additive mass renormalization with clover fermions and Symanzik improved gluons
A. Skouroupathis, M. Constantinou, H. Panagopoulos
We calculate the critical value of the hopping parameter, kappa_c, in Lattice QCD, up to two loops in perturbation theory. We employ the Sheikholeslami-Wohlert (clover) improved ac…
Open database for GPD analyses
V. D. Burkert, A. Camsonne, P. Chatagnon +7
This article summarizes the main ideas behind creating an open database proposed for use in the exploration of generalized parton distributions (GPDs). This lightweight database is…
Nucleon form factors and moments of parton distributions in twisted mass lattice QCD
C. Alexandrou, M. Brinet, J. Carbonell +7
We present results on the electroweak form factors and on the lower moments of parton distributions of the nucleon, within lattice QCD using two dynamical flavors of degenerate twi…
Perturbative subtraction of lattice artifacts in the computation of renormalization constants
M. Constantinou, M. Costa, M. Gockeler +6
The determination of renormalization factors is of crucial importance. They relate the observables obtained on finite, discrete lattices to their measured counterparts in the conti…
Renormalization of local quark-bilinear operators for Nf=3 flavors of SLiNC fermions
M. Constantinou, R. Horsley, H. Panagopoulos +5
The renormalization factors of local quark-bilinear operators are computed non-perturbatively for flavors of SLiNC fermions, with emphasis on the various procedures for the…
Nucleon form factors and moments of generalized parton distributions using twisted mass fermions
C. Alexandrou, M. Constantinou, S. Dinter +4
We present results on the axial and the electromagnetic form factors of the nucleon, as well as, on the first moments of the nucleon generalized parton distributions using maximall…
Neutron electric dipole moment using twisted mass fermions
C. Alexandrou, A. Athenodorou, M. Constantinou +5
We evaluate the neutron electric dipole moment using lattice QCD techniques. The gauge configurations analyzed are produced by the European Twisted Mass Coll…
Nucleon Structure in Lattice QCD using twisted mass fermions
C. Alexandrou, M. Constantinou, T Korzec +5
We present results on the nucleon form factors and moments of generalized parton distributions obtained within the twisted mass formulation of lattice QCD. We include a discussion…
The nucleon spin and momentum decomposition using lattice QCD simulations
C. Alexandrou, M. Constantinou, K. Hadjiyiannakou +5
We determine within lattice QCD, the nucleon spin carried by valence and sea quarks, and gluons. The calculation is performed using an ensemble of gauge configurations with two deg…
Perturbative and non-perturbative renormalization results of the Chromomagnetic Operator on the Lattice
M. Constantinou, M. Costa, R. Frezzotti +5
The Chromomagnetic operator (CMO) mixes with a large number of operators under renormalization. We identify which operators can mix with the CMO, at the quantum level. Even in dime…
Electrical analysis of hysteresis in solution processed silicon nanowire field effect transistors
K. Prabha Rajeev, C. Opoku, V. Stolojan +2
Silicon nanowires (Si NW) are ideal candidates for solution processable field effect transistors (FETs). The interface between the nanowire channel and the gate dielectric plays a…
Proton and neutron electromagnetic form factors from lattice QCD
C. Alexandrou, S. Bacchio, M. Constantinou +5
The electromagnetic form factors of the proton and the neutron are computed within lattice QCD using simulations with quarks masses fixed to their physical values. Both connected a…
and of the pion PDF from Lattice QCD with dynamical quark flavours
M. Oehm, C. Alexandrou, M. Constantinou +6
Using Nf=2+1+1 lattice QCD, we determine the fermionic connected contributions to the second and third moment of the pion PDF. Based on gauge configurations from the European Twist…
Nucleon spin and quark content at the physical point
C. Alexandrou, M. Constantinou, K. Hadjiyiannakou +5
We present results on the spin and quark content of the nucleon using twisted mass clover-improved fermion simulations with a pion mass close to its physical value. We use…
Renormalization of Flavor Singlet and Nonsinglet Fermion Bilinear Operators
M. Constantinou, M. Hadjiantonis, H. Panagopoulos
We compute the difference in the renormalization of flavor singlet and nonsinglet fermion bilinear operators, to two loops in perturbation theory. Our results are applicable to a r…
Thermodynamic properties of QCD in external magnetic fields
G. S. Bali, F. Bruckmann, M. Constantinou +8
We consider the effect of strong external electromagnetic fields on thermodynamic observables in QCD, through lattice simulations with 1+1+1 flavors of staggered quarks at physical…
QCD with overlap fermions: Running coupling and the 3-loop beta-function
M. Constantinou, H. Panagopoulos
We calculate the relation between the bare coupling constant g_0 and the MSbar-renormalized coupling g_MS: g_0 = Z_g(g_0,a μ) g_MS, to 2 loops in perturbation theory. We employ th…
LHCspin: a Polarized Gas Target for LHC
A. Accardi, A. Bacchetta, L. Barion +90
The goal of the LHCspin project is to develop innovative solutions for measuring the 3D structure of nucleons in high-energy polarized fixed-target collisions at LHC, exploring new…
Four-quark operators with in the GIRS scheme
M. Constantinou, M. Costa, H. Herodotou +2
We calculate the mixing matrices of four-quark operators that change flavor numbers by two units. Our approach employs two schemes: the coordinate-space Gauge Invariant Renormaliza…
First moment of the flavour octet nucleon parton distribution function using lattice QCD
C. Alexandrou, M. Constantinou, S. Dinter +5
We perform a lattice computation of the flavour octet contribution to the average quark momentum in a nucleon, $\la x\ra^{(8)}_{μ^2 = 4 \gev^2}$. In particular, we fully take the…
Magnetic susceptibility of QCD at zero and at finite temperature from the lattice
G. S. Bali, F. Bruckmann, M. Constantinou +5
The response of the QCD vacuum to a constant external (electro)magnetic field is studied through the tensor polarization of the chiral condensate and the magnetic susceptibility at…
Non-perturbative renormalization of quark bilinear operators with Nf=2 (tmQCD) Wilson fermions and the tree-level improved gauge action
M. Constantinou, P. Dimopoulos, R. Frezzotti +8
We present results for the renormalization constants of bilinear quark operators obtained by using the tree-level Symanzik improved gauge action and the Nf=2 twisted mass fermion a…
Perturbatively improving RI-MOM renormalization constants
M. Constantinou, M. Costa, M. Gockeler +6
The determination of renormalization factors is of crucial importance in lattice QCD. They relate the observables obtained on the lattice to their measured counterparts in the cont…
Science Requirements and Detector Concepts for the Electron-Ion Collider: EIC Yellow Report
R. Abdul Khalek, A. Accardi, J. Adam +410
This report describes the physics case, the resulting detector requirements, and the evolving detector concepts for the experimental program at the Electron-Ion Collider (EIC). The…
Nucleon scalar and tensor charges using lattice QCD simulations at the physical value of the pion mass
C. Alexandrou, M. Constantinou, P. Dimopoulos +9
We present results on the light, strange and charm nucleon scalar and tensor charges from lattice QCD, using simulations with flavors of twisted mass Clover-improved fermio…
The quark contents of the nucleon and their implication for dark matter search
C. Alexandrou, M. Constantinou, V. Drach +5
We present results concerning the light and strange quark contents of the nucleon using flavours of maximally twisted mass fermions. The corresponding -terms are ca…
Improved Perturbation Theory for Improved Lattice Actions
M. Constantinou, H. Panagopoulos, A. Skouroupathis
We study a systematic improvement of perturbation theory for gauge fields on the lattice; the improvement entails resumming, to all orders in the coupling constant, a dominant subc…
Gauge-invariant renormalization of four-quark operators
M. Constantinou, M. Costa, H. Herodotou +2
We study the renormalization of four-quark operators in one-loop perturbation theory. We employ a coordinate-space Gauge-Invariant Renormalization Scheme (GIRS), which can be advan…
Direct Evaluation of the Quark Content of Nucleons from Lattice QCD at the Physical Point
A. Abdel-Rehim, C. Alexandrou, M. Constantinou +5
We evaluate the light, strange and charm scalar content of the nucleon using one lattice QCD ensemble generated with two degenerate light quarks with mass fixed to their physical v…
Renormalization constants for 2-twist operators in twisted mass QCD
C. Alexandrou, M. Constantinou, T. Korzec +2
Perturbative and non-perturbative results on the renormalization constants of the fermion field and the twist-2 fermion bilinears are presented with emphasis on the non-perturbativ…
Gauge theories with overlap fermions in an arbitrary representation: Evaluation of the 3-loop beta-function
M. Constantinou, H. Panagopoulos
This work presents the calculation of the relation between the bare coupling constant g_0 and the MSbar-renormalized coupling g_MS, g_0 = Z_g(g_0,aμ) g_MS, to 2 loops in perturbat…
Renormalization constants for one-derivative fermion operators in twisted mass QCD
C. Alexandrou, M. Constantinou, T. Korzec +2
We present perturbative and non-perturbative results on the renormalization constants of the local and one-derivative vector and axial vector operators. Non-perturbative results ar…
Perturbatively improving renormalization constants
M. Constantinou, M. Costa, M. Gockeler +6
Renormalization factors relate the observables obtained on the lattice to their measured counterparts in the continuum in a suitable renormalization scheme. They have to be compute…
Renormalization constants of local operators for Wilson type improved fermions
C. Alexandrou, M. Constantinou, T. Korzec +2
Perturbative and non-perturbative results are presented on the renormalization constants of the quark field and the vector, axial-vector, pseudoscalar, scalar and tensor currents.…
Confronting lattice parton distributions with global QCD analysis
J. Bringewatt, N. Sato, W. Melnitchouk +3
We present the first Monte Carlo based global QCD analysis of spin-averaged and spin-dependent parton distribution functions (PDFs) that includes nucleon isovector matrix elements…
O(a^2) corrections to the one-loop propagator and bilinears of clover fermions with Symanzik improved gluons
M. Constantinou, V. Lubicz, H. Panagopoulos +1
We calculate corrections to the fermion propagator and to the Green's functions of all fermion bilinear operators of the form , to one-loop in perturbation theory. We e…
Perturbative renormalization functions of local operators for staggered fermions with stout improvement
M. Constantinou, M. Costa, H. Panagopoulos
In this paper we present the perturbative computation of the renormalization functions for the quark field and for a complete set of ultra-local fermion bilinears. The computation…
Sigma terms and strangeness content of the nucleon with twisted mass fermions
C. Alexandrou, M. Constantinou, S. Dinter +6
We investigate excited state contaminations in a direct computation of the nucleon -terms. This is an important source of systematic effects that needs to be controlled besides…
Three-dimensional imaging of hadrons with hard exclusive reactions: advances in experiment, theory, phenomenology, and lattice QCD
M. Boër, A. Camsonne, M. Constantinou +38
Generalized Parton Distributions (GPDs) have emerged as a powerful framework for exploring the internal structure of hadrons in terms of their partonic constituents. Over the past…
Flavor decomposition for the proton helicity parton distribution functions
C. Alexandrou, M. Constantinou, K. Hadjiyiannakou +2
We present, for the first time, an \textit{ab initio} calculation of the individual up, down and strange quark helicity parton distribution functions for the proton. The calculatio…
Axial Nucleon form factors from lattice QCD
C. Alexandrou, M. Brinet, J. Carbonell +6
We present results on the nucleon axial form factors within lattice QCD using two flavors of degenerate twisted mass fermions. Volume effects are examined using simulations at two…
The chromomagnetic operator on the lattice
M. Constantinou, M. Costa, R. Frezzotti +5
We study matrix elements of the "chromomagnetic" operator on the lattice. This operator is contained in the strangeness-changing effective Hamiltonian which describes electroweak e…
Measurement of the neutron charge radius and the role of its constituents
H. Atac, M. Constantinou, Z. -E. Meziani +2
The neutron is a cornerstone in our depiction of the visible universe. Despite the neutron zero-net electric charge, the asymmetric distribution of the positively- (up) and negativ…
Two-loop additive mass renormalization with clover fermions and Symanzik improved gluons
A. Skouroupathis, M. Constantinou, H. Panagopoulos
We calculate the critical value of the hopping parameter, , in Lattice QCD, up to two loops in perturbation theory. We employ the Sheikholeslami-Wohlert (clover) improved act…
Strong Interaction Physics at the Luminosity Frontier with 22 GeV Electrons at Jefferson Lab
A. Accardi, P. Achenbach, D. Adhikari +441
This document presents the initial scientific case for upgrading the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab (JLab) to 22 GeV. It is the result of a…
Singlet vs Nonsinglet Perturbative Renormalization of Fermion Bilinears
M. Constantinou, M. Hadjiantonis, H. Panagopoulos +1
In this paper we present the perturbative evaluation of the difference between the renormalization functions of flavor singlet and nonsinglet bilinear quark operators on the lattic…
Nucleon and pion structure with lattice QCD simulations at physical value of the pion mass
A. Abdel-Rehim, C. Alexandrou, M. Constantinou +12
We present results on the nucleon scalar, axial and tensor charges as well as on the momentum fraction, and the helicity and transversity moments. The pion momentum fraction is als…
matrix elements of the chromomagnetic operator on the lattice
M. Constantinou, M. Costa, R. Frezzotti +5
We present the results of the first lattice QCD calculation of the matrix elements of the chromomagnetic operator , which app…
Quark flavor decomposition of the nucleon axial form factors
C. Alexandrou, S. Bacchio, M. Constantinou +3
We present results on the isoscalar form factors including the disconnected contributions, as well as on the strange and charm quark form factors. Using previous results on the iso…
First moments of the nucleon transverse quark spin densities using lattice QCD
C. Alexandrou, S. Bacchio, M. Constantinou +9
We present a calculation of the Mellin moments of the transverse quark spin densities in the nucleon using lattice QCD. The densities are extracted from the unpolarized and transve…
BK-parameter from Nf = 2 twisted mass lattice QCD
ETM Collaboration, M. Constantinou, P. Dimopoulos +12
We present an unquenched lattice computation of the parameter which controls oscillations. A partially quenched setup is employed with two maximally…
Determination of the light, strange and charm quark masses using twisted mass fermions
C. Alexandrou, S. Bacchio, G. Bergner +23
We present results for the light, strange and charm quark masses using twisted mass fermion ensembles at three values of the lattice spacing, including two ensembles si…
Moments of nucleon generalized parton distributions from lattice QCD
C. Alexandrou, J. Carbonell, M. Constantinou +6
We present results on the lower moments of the nucleon generalized parton distri butions within lattice QCD using two dynamical flavors of degenerate twisted mass fermions. Our sim…