-
N. Carrasco,
P. Dimopoulos,
R. Frezzotti,
V. Gimenez, G. Herdoiza,
V. Lubicz,
G. Martinelli,
C. Michael,
D. Palao,
G. C. Rossi,
F. Sanfilippo,
A. Shindler,
S. Simula,
C. Tarantino
[show abstract]
[hide abstract]
ABSTRACT: We present a precise lattice QCD determination of the b-quark mass, of the B
and Bs decay constants and first results for the B-meson bag parameters. For
our computation we employ the so-called ratio method and our results benefit
from the use of improved interpolating operators for the B-mesons. QCD
calculations are performed with Nf = 2 dynamical light-quarks at four values of
the lattice spacing and the results are extrapolated to the continuum limit.
The preliminary results are mb(mb) = 4.35(12) GeV for the MSbar b-quark mass,
fBs = 234(6) MeV and fB = 197(10) MeV for the B-meson decay constants, BBs(mb)
= 0.90(5) and BB(mb) = 0.87(5) for the B-meson bag parameters.
12/2012;
-
N. Carrasco,
P. Dimopoulos,
R. Frezzotti,
V. Gimenez, G. Herdoiza,
V. Lubicz,
G. Martinelli,
D. Palao,
M. Papinutto,
G. C. Rossi,
F. Sanfilippo,
A. Shindler,
S. Simula,
C. Tarantino
[show abstract]
[hide abstract]
ABSTRACT: We present the ETMC results for the bag parameters describing the neutral
kaon mixing in the Standard Model and beyond and preliminary results for the
bag parameters controlling the short distance contributions in the
D^0-\bar{D}^0 oscillations. We also present preliminary results for the B_{Bd},
B_{Bs}, B_{Bs}/B_{Bd} and \xi -parameter controlling B^0_-\bar{B}^0
oscillations in the Standard Model employing the so-called ratio method. Using
Nf=2 maximally twisted sea quarks and Osterwalder-Seiler valence quarks we
achieve both O(a)-improvement and continuum like renormalization pattern.
Simulations are performed at three-values of the lattice spacing and several
values of quark masses in the light, strange, charm region and above charm up
to ~2.5m_c. Our results are extrapolated to the continuum limit and
extrapolated/interpolated to the physical quark masses.
11/2012;
-
ETM collaboration,
B. Blossier,
P. Dimopoulos,
R. Frezzotti, G. Herdoiza,
K. Jansen,
V. Lubicz,
G. Martinelli,
C. Michael,
G. C. Rossi,
A. Shindler,
S. Simula,
C. Tarantino,
C. Urbach
[show abstract]
[hide abstract]
ABSTRACT: A method to extract B-physics parameters (b-quark mass and f
B
, fBs {f_{{B_s}}} decay constants) from currently available lattice data is presented and tested. The approach is based on the idea of constructing
appropriate ratios of heavy-light meson masses and decay constants, respectively, possessing a precisely known static limit,
and evaluating them at various pairs of heavy quark masses around the charm. Via a smooth interpolation in the heavy quark
mass from the easily accessible charm region to the asymptotic point, B-physics parameters are computed with a few percent (statistical + systematic) error using recently produced N
f
= 2 maximally twisted Wilson fermions data.
KeywordsLattice QCD-Quark Masses and SM Parameters-B-Physics-Heavy Quark Physics
Journal of High Energy Physics 04/2012; 2010(4):1-25. · 5.83 Impact Factor
-
European Twisted Mass collaboration,
M. Constantinou,
P. Dimopoulos,
R. Frezzotti, G. Herdoiza,
K. Jansen,
V. Lubicz,
H. Panagopoulos,
G. C. Rossi,
S. Simula,
F. Stylianou,
A. Vladikas
[show abstract]
[hide abstract]
ABSTRACT: We present results for the renormalization constants of bilinear quark operators obtained by using the tree-level Symanzik
improved gauge action and the N
f
= 2 twisted mass fermion action at maximal twist, which guarantees automatic O \mathcal{O} (a)-improvement. Our results are also relevant for the corresponding standard (un-twisted) Wilson fermionic action since the
two actions only differ, in the massless limit, by a chiral rotation of the quark fields. The scale-independent renormalization
constants Z
V
, Z
A
and the ratio Z
P
/Z
S
have been computed using the RI-MOMapproach, as well as other alternative methods. For Z
A
and Z
P
/Z
S
, the latter are based on both standard twisted mass and Osterwalder-Seiler fermions, while for Z
V
a Ward Identity has been used. The quark field renormalization constant Z
q
and the scale dependent renormalization constants Z
S
, Z
P
and Z
T
are determined in the RI-MOM scheme. Leading discretization effects of O( g2a2 ) \mathcal{O}\left( {{g^2}{a^2}} \right) , evaluated in one-loop perturbation theory, are explicitly subtracted from the RI-MOM estimates.
KeywordsLattice QCD–Renormalization Regularization and Renormalons
Journal of High Energy Physics 04/2012; 2010(8):1-35. · 5.83 Impact Factor
-
B. Blossier,
M. Brinet,
N. Carrasco,
P. Dimopoulos,
X Du,
R. Frezzotti,
V. Gimenez, G. Herdoiza,
K. Jansen,
V. Lubicz,
D. Palao,
E. Pallante,
O. Pene,
K. Petrov,
S. Reker,
G. C. Rossi,
F. Sanfilippo,
L. Scorzato,
S. Simula,
C. Urbach
[show abstract]
[hide abstract]
ABSTRACT: We present preliminary results of the non-perturbative computation of the
RI-MOM renormalisation constants in a mass-independent scheme for the action
with Iwasaki glue and four dynamical Wilson quarks employed by ETMC. Our
project requires dedicated gauge ensembles with four degenerate sea quark
flavours at three lattice spacings and at several values of the standard and
twisted quark mass parameters. The RI-MOM renormalisation constants are
obtained from appropriate O(a) improved estimators extrapolated to the chiral
limit.
12/2011;
-
ETM Collaboration,
P. Dimopoulos,
R. Frezzotti, G. Herdoiza,
V. Lubicz,
C. Michael,
D. Palao,
G. C. Rossi,
F. Sanfilippo,
A. Shindler,
S. Simula,
C. Tarantino,
M. Wagner
[show abstract]
[hide abstract]
ABSTRACT: We present a lattice QCD determination of the b quark mass and of the B and
B_s decay constants, performed with N_f=2 twisted mass Wilson fermions, by
simulating at four values of the lattice spacing. In order to study the b quark
on the lattice, two methods are adopted in the present work, respectively based
on suitable ratios with exactly known static limit and on the interpolation
between relativistic data, evaluated in the charm mass region, and the static
point, obtained by simulating the HQET on the lattice. The two methods provide
results in good agreement. For the b quark mass in the MSbar scheme and for the
decay constants we obtain m_b(m_b)=4.29(14) GeV, f_B=195(12) MeV, f_Bs=232(10)
MeV and f_Bs/f_B=1.19(5). As a byproduct of the analysis we also obtain the
results for the f_D and f_Ds decay constants: f_D=212(8) MeV, f_Ds=248(6) MeV
and f_Ds/f_D=1.17(5).
07/2011;
-
[show abstract]
[hide abstract]
ABSTRACT: We report on an ongoing non-perturbative computation of RI-MOM scheme
renormalization constants for the lattice action with four dynamical flavours
currently in use by ETMC. For this goal dedicated simulations with four
degenerate sea quark flavours are performed at several values of the standard
and twisted quark mass parameters. We discuss a method for removing possible
O(a) artifacts at all momenta and extrapolating renormalization constant
estimators to the chiral limit. We give preliminary results at one lattice
spacing.
01/2011;
-
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;
-
[show abstract]
[hide abstract]
ABSTRACT: We study light-quark observables by means of dynamical lattice QCD simulations using two flavours of twisted mass fermions at maximal twist. We employ chiral perturbation theory to describe our data for the pion mass and decay constant. In this way, we extract precise determinations for the low-energy constants of the effective theory as well as for the light-quark mass and the chiral condensate. Comment: 8 pages, 2 figures, presented at the XXVII International Symposium on Lattice Field Theory, July 26-31, 2009, Peking University, Beijing, China
12/2009;
-
[show abstract]
[hide abstract]
ABSTRACT: We study lattice QCD determinations of the pion mass and decay constant by means of chiral perturbation theory (ChPT). The lattice data are obtained from large scale simulations with N_f=2 flavours of twisted mass fermions at maximal twist. We perform a scaling test to the continuum limit of these data and use ChPT to perform both the chiral and the infinite volume extrapolations. Comment: 8 pages, 4 figures, presented at International Workshop on Effective Field Theories: From the Pion to the Upsilon (EFT 09), Valencia, Spain, 2-6 Feb 2009
12/2009;
-
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;
-
ETM Collaboration,
B. Blossier,
P. Dimopoulos,
R. Frezzotti, G. Herdoiza,
K. Jansen,
V. Lubicz,
G Martinelli,
C. Michael,
G. C. Rossi,
F. Sanfilippo,
A. Shindler,
S. Simula,
C. Tarantino,
C. Urbach,
M. Wagner
[show abstract]
[hide abstract]
ABSTRACT: We present a lattice QCD calculation of the heavy-light decay constants f_B and f_Bs performed with Nf=2 maximally twisted Wilson fermions, at four values of the lattice spacing. The decay constants have been also computed in the static limit and the results are used to interpolate the observables between the charm and the infinite-mass sectors, thus obtaining the value of the decay constants at the physical b quark mass. Our preliminary results are f_B=191(14) MeV, f_Bs=243(14) MeV, f_Bs/f_B=1.27(5). They are in good agreement with those obtained with a novel approach, recently proposed by our Collaboration (ETMC), based on the use of suitable ratios having an exactly known static limit. Comment: Proceedings of the 27th International Symposium on Lattice Field Theory (Lattice 2009), Beijing, China, 2009 July 26-31. 8 pages, 3 figures
11/2009;
-
European Twisted Mass collaboration,
B. Blossier,
P. Dimopoulos,
R. Frezzotti,
B. Haas, G. Herdoiza,
K. Jansen,
V. Lubicz,
F. Mescia,
D. Palao,
A. Shindler,
S. Simula,
C. Tarantino,
C. Urbach,
U. Wenger
[show abstract]
[hide abstract]
ABSTRACT: We present the results of a lattice QCD calculation of the pseudoscalar meson decay constants fπ, fK, fD and fDs, performed with Nf = 2 dynamical fermions. The simulation is carried out with the tree-level improved Symanzik gauge action and with the twisted mass fermionic action at maximal twist. We have considered for the final analysis three values of the lattice spacing, a 0.10 fm, 0.09 fm and 0.07 fm, with pion masses down to mπ 270 MeV. Our results for the light meson decay constants are fK = 158.1(2.4) MeV and fK/fπ = 1.210(18). From the latter ratio, by using the experimental determination of Γ(K → μμ(γ))/Γ(π → μμ(γ)) and the average value of |Vud| from nuclear beta decays, we obtain |Vus| = 0.2222(34), in good agreement with the determination from semileptonic Kl3 decays and the unitarity constraint. For the D and Ds meson decay constants we obtain fD = 197(9) MeV, fDs = 244(8) MeV and fDs/fD = 1.24(3). Our result for fD is in good agreement with the CLEO experimental measurement. For fDs our determination is smaller than the PDG 2008 experimental average but in agreement with a recent improved measurement by CLEO at the 1.4 σ level.
Journal of High Energy Physics 07/2009; 2009(07):043. · 5.83 Impact Factor
-
B. Blossier,
P. Dimopoulos,
R. Frezzotti,
B. Haas, G. Herdoiza,
K. Jansen,
V. Lubicz,
F. Mescia,
D. Palao,
A. Shindler,
S. Simula,
C. Tarantino,
C. Urbach,
U. Wenger,
ETM Collaboration
[show abstract]
[hide abstract]
ABSTRACT: We present the results of a lattice QCD calculation of the pseudoscalar meson decay constants fpi, fK, fD and fDs, performed with Nf=2 dynamical fermions. The simulation is carried out with the tree-level improved Symanzik gauge action and with the twisted mass fermionic action at maximal twist. We have considered for the final analysis three values of the lattice spacing, a~0.10 fm, 0.09 fm and 0.07 fm, with pion masses down to mpi~270 MeV. Our results for the light meson decay constants are fK=158.1(2.4) MeV and fK/fpi=1.210(18). From the latter ratio, by using the experimental determination of Gamma(K-->mu nu_mu (gamma))/ Gamma(pi--> mu nu_mu (gamma)) and the average value of |Vud| from nuclear beta decays, we obtain |Vus|=0.2222(34), in good agreement with the determination from semileptonic Kl3 decays and the unitarity constraint. For the D and Ds meson decay constants we obtain fD=197(9) MeV, fDs=244(8) MeV and fDs/fD=1.24(3). Our result for fD is in good agreement with the CLEO experimental measurement. For fDs our determination is smaller than the PDG 2008 experimental average but in agreement with a recent improved measurement by CLEO at the 1.4 sigma level.
05/2009;
-
[show abstract]
[hide abstract]
ABSTRACT: We present an update of the results for pion mass and pion decay constant as obtained by the ETM collaboration in large scale simulations with maximally twisted mass fermions and two mass degenerate flavours of light quarks. We discuss the continuum, chiral and infinite volume extrapolation of these quantities as well as the extraction of low energy constants, and investigate possible systematic uncertainties. Comment: 7 pages, 2 figures, talk presented at the XXVI International Symposium on Lattice Field Theory, July 14-19, 2008, Williamsburg, Virginia, USA
10/2008;
-
C. Alexandrou,
R. Baron,
B. Blossier,
M. Brinet,
J. Carbonell,
P. Dimopoulos,
V. Drach,
F. Farchioni,
R. Frezzotti,
P. Guichon, G. Herdoiza,
K. Jansen,
T. Korzec,
G. Koutsou,
Z Liu,
C. Michael,
O. Pène,
A. Shindler,
C. Urbach,
U. Wenger
[show abstract]
[hide abstract]
ABSTRACT: We present results on the mass of the nucleon and the Delta using two dynamical degenerate twisted mass quarks and the tree-level Symanzik improved gauge action. The evaluation is performed at four quark masses corresponding to a pion mass in the range of about 300-600 MeV on lattices of 2.1-2.7 fm. We check for cut-off effects by evaluating these baryon masses on lattices of spatial size 2.1 fm at beta=3.9 and beta=4.05 and on a lattice of 2.4 fm at beta=3.8. The values we find are compatible within our statistical errors. Lattice results are extrapolated to the physical limit using continuum chiral perturbation theory. Performing a combined fit to our lattice data at beta=3.9 and beta=4.05 we find a nucleon mass of 964\pm 28 (stat.) \pm 8 (syst.) MeV. The nucleon mass at the physical point provides an independent determination of the lattice spacing. Using heavy baryon chiral perturbation theory at O(p^3) we find a_{\beta=3.9}=0.0890\pm 0.0039(stat.) \pm 0.0014(syst.) fm, and a_{\beta=4.05}= 0.0691\pm 0.0034(stat.) \pm 0.0010(syst.) fm, in good agreement with the values determined from the pion decay constant. Isospin violating lattice artifacts in the Delta-system are found to be compatible with zero for the values of the lattice spacings used in this work. Performing a combined fit to our lattice data at beta=3.9 and beta=4.05 we find for the masses of the Delta^{++,-} and Delta^{+,0} 1316 \pm 60 (stat.) MeV and 1330 \pm 74 (stat.) MeV respectively. We confirm that in the continuum limit they are also degenerate.
04/2008;
-
ETM Collaboration,
B. Blossier,
Ph. Boucaud,
P. Dimopoulos,
F. Farchioni,
R. Frezzotti,
V. Gimenez, G. Herdoiza,
K. Jansen,
V. Lubicz,
C. Michael,
D. Palao,
M. Papinutto,
A. Shindler,
S. Simula,
C. Tarantino,
C. Urbach,
U. Wenger
[show abstract]
[hide abstract]
ABSTRACT: We present the results of a lattice QCD calculation of the average up-down and strange quark masses and of the light meson pseudoscalar decay constants with Nf = 2 dynamical fermions. The simulation is carried out at a single value of the lattice spacing with the twisted mass fermionic action at maximal twist, which guarantees automatic (a)-improvement of the physical quantities. Quark masses are renormalized by implementing the non perturbative RI-MOM renormalization procedure. Our results for the light quark masses are mud(2 GeV) = 3.85±0.12±0.40 MeV, ms(2 GeV) = 105±3±9 MeV and ms/mud = 27.3±0.3±1.2. We also obtain fK = 161.7±1.2±3.1 MeV and the ratio fK/fπ = 1.227±0.009±0.024. From this ratio, by using the experimental determination of Γ(K → μμ(γ))/Γ(π → μμ(γ)) and the average value of |Vud| from nuclear beta decays, we obtain |Vus| = 0.2192(5)(45), in agreement with the determination from Kl3 decays and the unitarity constraint.
Journal of High Energy Physics 04/2008; 2008(04):020. · 5.83 Impact Factor
-
Ph. Boucaud,
P. Dimopoulos,
F. Farchioni,
R. Frezzotti,
V. Gimenez, G. Herdoiza,
K. Jansen,
V. Lubicz,
C. Michael,
G. Münster,
D. Palao,
G. C. Rossi,
L. Scorzato,
A. Shindler,
S. Simula,
T. Sudmann,
C. Urbach,
U. Wenger,
ETM Collaboration
[show abstract]
[hide abstract]
ABSTRACT: In a recent paper [hep-lat/0701012] we presented precise lattice QCD results of our European Twisted Mass Collaboration (ETMC). They were obtained by employing two mass-degenerate flavours of twisted mass fermions at maximal twist. In the present paper we give details on our simulations and the computation of physical observables. In particular, we discuss the problem of tuning to maximal twist, the techniques we have used to compute correlators and error estimates. In addition, we provide more information on the algorithm used, the autocorrelation times and scale determination, the evaluation of disconnected contributions and the description of our data by means of chiral perturbation theory formulae. Comment: March 2008. 59pp. Minor changes. Added references
03/2008;
-
[show abstract]
[hide abstract]
ABSTRACT: We report on the scaling of basic hadronic observables in lattice QCD with N_f=2 maximally twisted Wilson dynamical quarks. We give preliminary results for some of the Gasser-Leutwyler low energy constants, the chiral condensate and the average mass of u and d quarks.
11/2007;
-
[show abstract]
[hide abstract]
ABSTRACT: We present preliminary results for the charm quark mass $m_c$ and the $D$ and $D_s$ mesons decay constants $f_D$ and $f_{D_s}$ from a lattice QCD calculation with ${\rm N_f}$ = 2 dynamical fermions. We use the twisted mass fermionic action defined at maximal twist so that physical quantities are automatically ${\cal O}(a)$ improved. Two lattice spacings are considered. The charm quark mass has been renormalised in the RI-MOM scheme. After a matching to the $\msb$ scheme, we obtain from the simulation at a fine lattice ($a \sim 0.09$ fm) $m_c^{\msb}(m_c) = 1.481 \pm 0.022 \pm 0.092$ GeV, $f_D = 205 \pm 13 \pm 17$ MeV, $f_{D_s} = 271 \pm 6 \pm 6$ MeV and from the simulation at the finer lattice ($a \sim 0.07$ fm) $m_c^{\msb}(m_c) = 1.474 \pm 0.041 \pm 0.132$ GeV, $f_D = 230 \pm 31 \pm 8$ MeV and $f_{D_s} = 264 \pm 5 \pm 8$ MeV. We chose three renormalisation conditions to determine $m_c$: the spread between the final results contributes to the systematic error. At both lattice spacings, particularly at the finer one, the error on $m_c$ is dominated by present uncertainty on the renormalisation constant $Z_P$, which should be reduced before performing a reliable continuum limit.
11/2007;
