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R. Baron,
B. Blossier, P. Boucaud,
J. Carbonell,
A. Deuzeman,
V. Drach,
F. Farchioni,
V. Gimenez,
G. Herdoiza,
K. Jansen,
C. Michael,
I. Montvay,
E. Pallante,
O. Pène,
S. Reker,
C. Urbach,
M. Wagner,
U. Wenger,
for the ETM Collaboration
[show abstract]
[hide abstract]
ABSTRACT: We present results of lattice QCD simulations with mass-degenerate up and
down and mass-split strange and charm (Nf=2+1+1) dynamical quarks using Wilson
twisted mass fermions at maximal twist. The tuning of the strange and charm
quark masses is performed at three values of the lattice spacing a~0.06 fm,
a~0.08 fm and a~0.09 fm with lattice sizes ranging from L~1.9 fm to L~3.9 fm.
We perform a preliminary study of SU(2) chiral perturbation theory by combining
our lattice data from these three values of the lattice spacing.
01/2011;
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R. Baron,
B. Blossier, P. Boucaud,
A. Deuzeman,
V. Drach,
F. Farchioni,
V. Gimenez,
G. Herdoiza,
K. Jansen,
C. Michael,
I. Montvay,
D. Palao,
E. Pallante,
O. Pène,
S. Reker,
C. Urbach,
M. Wagner,
U. Wenger,
for the ETM Collaboration
[show abstract]
[hide abstract]
ABSTRACT: We present first results from runs performed with Nf=2+1+1 flavours of dynamical twisted mass fermions at maximal twist: a degenerate light doublet and a mass split heavy doublet. An overview of the input parameters and tuning status of our ensembles is given, together with a comparison with results obtained with Nf=2 flavours. The problem of extracting the mass of the K- and D-mesons is discussed, and the tuning of the strange and charm quark masses examined. Finally we compare two methods of extracting the lattice spacings to check the consistency of our data and we present some first results of ChiPT fits in the light meson sector. Comment: 8 pages, 4 figures. Talk presented at the XXVII International Symposium on Lattice Field Theory, July 26-31 2009, Peking University, Beijing, China
11/2009;
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F. Belletti,
S.F. Schifano,
R. Tripiccione,
F. Bodin, P. Boucaud,
J. Micheli,
O. Pene,
N. Cabibbo,
S. de Luca,
A. Lonardo,
D. Rossetti,
P. Vicini,
M. Lukyanov,
L. Morin,
N. Paschedag,
H. Simma,
V. Morenas,
D. Pleiter,
F. Rapuano
[show abstract]
[hide abstract]
ABSTRACT: apeNEXT is the latest in the APE collaboration's series of parallel computers for computationally intensive calculations such as quantum chromo dynamics on the lattice. The authors describe the computer architectural choices that have been shaped by almost two decades of collaboration activity.
Computing in Science and Engineering 02/2006; · 1.42 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: We present the first direct evaluation of DI = 3/2 K -> pi pi matrix elements with the aim of determining all the low-energy constants at NLO in the chiral expansion. Our numerical investigation demonstrates that it is indeed possible to determine the K -> pi pi matrix elements directly for the masses and momenta used in the simulation with good precision. In this range however, we find that the matrix elements do not satisfy the predictions of NLO chiral perturbation theory. For the chiral extrapolation we therefore use a hybrid procedure which combines the observed polynomial behaviour in masses and momenta of our lattice results, with NLO chiral perturbation theory at lower masses. In this way we find stable results for the quenched matrix elements of the electroweak penguin operators (<pi pi (I=2)|O_8|K^0>= (0.68 +- 0.09) GeV^3 and <pi pi (I=2)|O_7|K^0>= (0.12 +- 0.02) GeV^3 in the NDR-MSbar scheme at the scale 2 GeV), but not for the matrix elements of O_4 (for which there are too many Low-Energy Constants at NLO for a reliable extrapolation). For all three operators we find that the effect of including the NLO corrections is significant (typically about 30%). We present a detailed discussion of the status of the prospects for the reduction of the systematic uncertainties.
01/2005;
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[show abstract]
[hide abstract]
ABSTRACT: The results of a preliminary partially quenched (N_f=2) study of the light hadron spectrum, renormalization constants and light quark masses are presented. Numerical simulations are carried out with the LL-SSOR preconditioned Hybrid Monte Carlo with two degenerate dynamical fermions, using the plaquette gauge action and the Wilson quark action at beta = 5.8. Finite volume effects have been investigated employing two lattice volumes: 16^3 x 48 and 24^3 x 48. Configurations have been generated at four values of the sea quark mass corresponding to M_{PS}/M_V ~ 0.6 - 0.8. Comment: 3 pages, 3 figures, Lattice2004(spectrum)
09/2004;
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F. Bodin, P. Boucaud,
N. Cabibbo,
F. Calvayrac,
M. Della Morte,
R. De Pietri,
P. De Riso,
F. Di Carlo,
F. Di Renzo,
W. Errico, [......],
O. Pene,
R. Petronzio,
D. Pleiter,
F. Rapuano,
D. Rossetti,
L Sartori,
H. Simma,
F. Schifano,
R. Tripiccione,
P. Vicini
[show abstract]
[hide abstract]
ABSTRACT: APENEXT is a new generation APE processor, optimized for LGT simulations. The project follows the basic ideas of previous APE machines and develops simple and cheap parallel systems with multi T-Flops processing power. This paper describes the main features of this new development. Comment: Lattice2001(plenary/machinestatus), 4 pages, 1 eps figure
10/2001;
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APE-Collaboration: A. Bartoloni, P. Boucaud,
N. Cabibbo,
F. Calvayrac,
M. Della Morte,
R. De Pietri,
P. De Riso,
F. Di Carlo,
F. Di Renzo,
W. Errico, [......],
F. Rapuano,
J. Rolf,
D. Rossetti,
L Sartori,
H. Simma,
F. Schifano,
M. Torelli,
R. Tripiccione,
P. Vicini,
P. Wegner
[show abstract]
[hide abstract]
ABSTRACT: This paper presents the status of the APEmille project, which is essentially completed, as far as machine development and construction is concerned. Several large installations of APEmille are in use for physics production runs leading to many new results presented at this conference. This paper briefly summarizes the APEmille architecture, reviews the status of the installations and presents some performance figures for physics codes. Comment: Lattice2001(algorithms), 3 pages, 1 eps figure
10/2001;
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R. Baron,
DESY DESY Standort Zeuthen, P. Boucaud,
J. Carbonell,
V. Drach,
F. Farchioni,
G. Herdoiza,
K. Jansen,
C. Michael,
I. Montvay,
E. Pallante,
O. Pene,
S. Reker,
C. Urbach,
M. Wagner,
U. Wenger
Comput. Phys. Commun. 182(2010),299.
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R. Baron,
DESY DESY Standort Zeuthen,
The International Symposium on Lattice Field Theory Villasimius Lattice Italy, P. Boucaud,
J. Carbonell,
V. Drach,
F. Farchioni,
G. Herdoiza,
K. Jansen,
C. Michael,
I. Montvay,
E. Pallante,
S. Reker,
C. Urbach,
M. Wagner,
U. Wenger
The 28th International Symposium on Lattice Field Theory,Villasimius,Italy PoS(2010),119.
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R. Baron,
DESY DESY Standort Zeuthen,
B. Blossier, P. Boucaud,
A. Deuzeman,
V. Drach,
F. Farchioni,
V. Gimenez,
G. Herdoiza,
K. Jansen,
C. Michael,
I. Montvay,
D. Palao,
E. Pallante,
O. Pene,
S. Reker,
C. Urbach,
M. Wagner,
U. Wenger,
ETM Collaboration
27. International Symposium on Lattice Field Theory,Beijing,China (2009),104.
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R. Baron,
B. Blossier, P. Boucaud,
A. Deuzeman,
V. Drach,
F. Farchioni,
V. Gimenez,
G. Herdoiza,
K. Jansen,
C. Michael,
I. Montvay,
D. Palao,
E. Pallante,
O. Pène,
S. Reker,
C. Urbach,
M. Wagner,
U. Wenger
27th International Symposium on Lattice Field Theory,Beijing,China LAT2009(2009),104.
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ETM Collaboration,
DESY DESY Standort Zeuthen,
R. Baron, P. Boucaud,
J. Carbonell,
V. Drach,
F. Farchioni,
G. Herdoiza,
K. Jansen,
C. Michael,
I. Montvay,
E. Pallante,
O. Pene,
S. Reker,
C. Urbach,
M. Wagner,
U. Wenger
Red Report (2010),.
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R. Baron,
DESY DESY Standort Zeuthen,
The International Symposium on Lattice Field Theory Villasimius Lattice Italy,
B. Blossier, P. Boucaud,
J. Carbonell,
A. Deuzeman,
V. Drach,
F. Farchioni,
V. Gimenez,
G. Herdoiza,
K. Jansen,
C. Michael,
I. Montvay,
E. Pallante,
O. Pene,
S. Reker,
C. Urbach,
M. Wagner,
U. Wenger
The 28th International Symposium on Lattice Field Theory,Villasimius,Italy PoS(2010),123.
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A. Abada, P. Boucaud,
Nicola Cabibbo,
M. Crisafulli,
J. P. Leroy,
V. Lubicz,
G Martinelli,
F. Rapuano,
M. Serone,
N. Stella,
A Bartoloni,
C. Battista,
S. Cabasino,
E. Panizzi,
P. S. Paolucci,
R. Sarno,
G. M. Todesco,
M. Torelli,
P. Vicini
[show abstract]
[hide abstract]
ABSTRACT: We present the results of a numerical calculation of the B\rightarrow K^* \gamma form factors. The results have been obtained by studying the relevant correlation functions at \beta=6.0, on an 18^3 \times 64 lattice, using the {\rm O(a)}-improved fermion action, in the quenched approximation. From the study of the matrix element \langle K^*\vert \bar s \sigma_{\mu\nu} b \vert B\rangle we have obtained the form factor T_1(0) which controls the exclusive decay rate. The results are compared with the recent results from CLEO. We also discuss the compatibility between the scaling laws predicted by the Heavy Quark Effective Theory (HQET) and pole dominance, by studying the mass- and q^2-dependence of the form factors. From our analysis, it appears that the form factors follow a mass behaviour compatible with the predictions of the HQET and that the q^2-dependence of T_2 is weaker than would be predicted by pole dominance.
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R. Baron,
DESY DESY Standort Zeuthen, P. Boucaud,
P. Dimopoulos,
F. Farchioni,
R. Frezzotti,
V. Gimenez,
G. Herdoiza,
K. Jansen,
V. Lubicz,
C. Michael,
G. Muenster,
D. Palao,
G. C. Rossi,
L. Scorzato,
A. Shindler,
S. Simula,
T. Sudmann,
C. Urbach,
U. Wenger
Red Report (2009),.
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A. Abada,
C. R. Allton, P. Boucaud,
D. B. Carpenter,
M. Crisafulli,
J Galand,
S. Güsken,
G Martinelli,
O. Pène,
Christopher T C Sachrajda,
R. Sarno,
K. Schilling,
Rainer Sommer
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Phys. Lett. B 650(2007)4,304-311.
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[show abstract]
[hide abstract]
ABSTRACT: The $B$-meson decay constant can be measured on the lattice using a $1/m_b$ expansion. To relate the physical quantity to Monte Carlo data one has to know the renormalization coefficient, $Z$, between the lattice operators and their continuum counterparts. We come back to this computation to resolve discrepancies found in previous calculations. We define and discuss in detail the renormalization procedure that allows the (perturbative) computation of $Z$. Comparing the one-loop calculations in the effective Lagrangian approach with the direct two-loop calculation of the two-point $B$-meson correlator in the limit of large $b$-quark mass, we prove that the two schemes give consistent results to order $\alpha_s$. We show that there is, however, a renormalization prescription ambiguity that can have sizeable numerical consequences. This ambiguity can be resolved in the framework of an $O(a)$ improved calculation, and we describe the correct prescription in that case. Finally we give the numerical values of $Z$ that correspond to the different types of lattice approximations discussed in the paper.
