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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
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[show abstract]
[hide abstract]
ABSTRACT: We determine Lambda_msbar for QCD with n_f=2 dynamical quark flavors by
fitting the Q-Q-bar static potential known analytically in the perturbative
regime up to terms of O(alpha_s^4) and ~alpha_s^4 ln(alpha_s) to corresponding
results obtained from lattice simulations. This has become possible, due to
recent advances in both perturbative calculations, namely the determination and
publication of the last missing contribution to the Q-Q-bar static potential at
O(alpha_s^4), and lattice simulations with n_f=2 dynamical quark flavors
performed at the rather fine lattice spacing of a~0.042 fm. Imposing
conservative error estimates we obtain Lambda_msbar=315(30) MeV.
10/2011;
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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;
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[show abstract]
[hide abstract]
ABSTRACT: I report on a lattice computation of the energy of a system of two light
quarks and two static antiquarks as a function of the separation of the static
antiquarks. In terms of hadrons such a system corresponds to a pair of B mesons
and its energy to the hadronic potential. I present selected results for
different isospin, spin and parity combinations of the individual B mesons
mainly focusing on those channels relevant to determine, whether two B mesons
may form a bound tetraquark state.
03/2011;
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ETM Collaboration,
P. Dimopoulos,
R. Frezzotti,
V. Gimenez,
V. Lubicz,
G Martinelli,
F. Mescia,
M. Papinutto,
G. C. Rossi,
S. Simula,
A. Vladikas
[show abstract]
[hide abstract]
ABSTRACT: We present preliminary results on the of neutral kaon oscillations in extensions of the Standard Model. Using Nf=2 maximally twisted sea quarks and Osterwalder-Seiler valence quarks, we achieve both O(a)-improvement and continuum-like renormalization pattern for the relevant four-fermion operators. We perform simulations at three values of the lattice spacing and extrapolate/interpolate our results to the continuum limit and physical light/strange quark mass. The calculation of the renormalization constants of the complete operator basis is performed non- perturbatively in the RI-MOM scheme. Comment: 7 pages, 2 figures; presented at the XXVIII International Symposium on Lattice Field Theory Villasimius, Sardinia, Italy
12/2010;
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[show abstract]
[hide abstract]
ABSTRACT: We present first results for the pseudoscalar decay constants $f_K$, $f_D$ and $f_{D_s}$ from lattice QCD with N_f=2+1+1 flavours of dynamical quarks. The lattice simulations have been performed by the European Twisted Mass collaboration (ETMC) using maximally twisted mass quarks. For the pseudoscalar decay constants we follow a mixed action approach by using so called Osterwalder-Seiler fermions in the valence sector for strange and charm quarks. The data for two values of the lattice spacing and several values of the up/down quark mass is analysed using chiral perturbation theory. Comment: 7 pages, 2 figures, presented at the XXVIII International Symposium on Lattice Field Theory, Lattice 2010
12/2010;
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[show abstract]
[hide abstract]
ABSTRACT: We present a high precision lattice calculation of the average up/down,
strange and charm quark masses performed with Nf=2 twisted mass Wilson
fermions. The analysis includes data at four values of the lattice spacing and
pion masses as low as ~270 MeV, allowing for accurate continuum limit and
chiral extrapolation. The strange and charm masses are extracted by using
several methods, based on different observables: the kaon and the eta_s meson
for the strange quark and the D, D_s and eta_c mesons for the charm. The quark
mass renormalization is carried out non-perturbatively using the RI-MOM method.
The results for the quark masses in the MSbar scheme read: m_ud(2 GeV)= 3.6(2)
MeV, m_s(2 GeV)=95(6) MeV and m_c(m_c)=1.28(4) GeV. We also obtain the ratios
m_s/m_ud=27.3(9) and m_c/m_s=12.0(3).
10/2010;
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ETM Collaboration,
M. Constantinou,
P. Dimopoulos,
R. Frezzotti,
K. Jansen,
V. Gimenez,
V. Lubicz,
F. Mescia,
H. Panagopoulos,
M. Papinutto,
G. C. Rossi,
S. Simula,
A. Skouroupathis,
F. Stylianou,
A. Vladikas
[show abstract]
[hide abstract]
ABSTRACT: We present an unquenched $N_f=2$ lattice computation of the $B_{K}$ parameter
which controls $K^0-\bar K^0$ oscillations. A partially quenched setup is
employed with two maximally twisted dynamical (sea) light Wilson quarks, and
valence quarks of both the maximally twisted and the Osterwalder--Seiler
variety. Suitable combinations of these two kinds of valence quarks lead to a
lattice definition of the $B_{K}$ parameter which is both multiplicatively
renormalizable and O($a$) improved. Employing the non-perturbative RI-MOM
scheme, in the continuum limit and at the physical value of the pion mass we
get $B^{\rm RGI}_K=0.729\pm 0.030$, a number well in line with the existing
quenched and unquenched determinations.
09/2010;
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ETM Collaboration,
Remi Baron,
Philippe Boucaud,
Jaume Carbonell,
Vincent Drach,
Federico Farchioni,
Gregorio Herdoiza,
Karl Jansen,
Chris Michael,
Istvan Montvay,
Elisabetta Pallante,
Siebren Reker,
Carsten Urbach,
Marc Wagner,
Urs Wenger
[show abstract]
[hide abstract]
ABSTRACT: We discuss the computation of the kaon and D meson masses in the N_f = 2+1+1 twisted mass lattice QCD setup, where explicit heavy flavor and parity breaking occurs at finite lattice spacing. We present three methods suitable in this context and verify their consistency. Comment: 7 pages, 3 figures, talk given at the XXVIII International Symposium on Lattice Field Theory (Lattice 2010), June 14-19 2010, Villasimius, Italy
09/2010;
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Remi Baron,
Philippe Boucaud,
Jaume Carbonell,
Albert Deuzeman,
Vincent Drach,
Federico Farchioni,
Vicent Gimenez,
Gregorio Herdoiza,
Karl Jansen,
Craig McNeile,
Chris Michael,
Istvan Montvay,
David Palao,
Elisabetta Pallante,
Olivier Pene,
Siebren Reker,
Carsten Urbach,
Marc Wagner,
Urs Wenger, 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 (N_f = 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 two values of the lattice spacing a~0.078 fm and a~0.086 fm with lattice sizes ranging from L~1.9 fm to L~2.8 fm. We measure with high statistical precision the light pseudoscalar mass m_PS and decay constant f_PS in a range 270 < m_PS < 510 MeV and determine the low energy parameters f_0, l_3 and l_4 of SU(2) chiral perturbation theory. We use the two values of the lattice spacing, several lattice sizes as well as different values of the light, strange and charm quark masses to explore the systematic effects. A first study of discretisation effects in light-quark observables and a comparison to N_f=2 results are performed. Comment: 31 pages, 14 figures
Journal of High Energy Physics 04/2010; · 5.83 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: We investigate the continuum limit of the low lying static-light meson spectrum using Wilson twisted mass lattice QCD with N_f = 2 dynamical quark flavours. We consider three values of the lattice spacing a ~ 0.051 fm, 0.064 fm, 0.080 fm and various values of the pion mass in the range 280 MeV < m_PS < 640 MeV. We present results in the continuum limit for light cloud angular momentum j = 1/2, 3/2, 5/2 and for parity P = +, -. We extrapolate our results to physical quark masses, make predictions regarding the spectrum of B and B_s mesons and compare with available experimental results. Comment: 18 pages, 3 figures
04/2010;
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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;
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[show abstract]
[hide abstract]
ABSTRACT: We perform a two-flavor dynamical lattice computation of the Isgur-Wise functions tau_{1/2} and tau_{3/2} at zero recoil in the static limit. We find tau_{1/2}(1) = 0.297(26) and tau_{3/2}(1) = 0.528(23) fulfilling Uraltsev's sum rule by around 80%. We also comment on a persistent conflict between theory and experiment regarding semileptonic decays of B mesons into orbitally excited P wave D mesons, the so-called "1/2 versus 3/2 puzzle", and we discuss the relevance of lattice results in this context. Comment: 7 pages, 2 figures, talk given at the XXVII International Symposium on Lattice Field Theory, July 26 - 31 2009, Peking University, Beijing, China
09/2009;
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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;
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[show abstract]
[hide abstract]
ABSTRACT: We perform a dynamical lattice computation of the Isgur-Wise functions tau_{1/2} and tau_{3/2} at zero recoil. We consider three different light quark masses corresponding to 300 MeV < m_{PS} < 450 MeV, which allow us to extrapolate our results to the physical u/d quark mass. We find tau_{1/2}(1) = 0.296(26) and tau_{3/2}(1) = 0.526(23). Uraltsev's sum rule is saturated up to 80% by the ground state. We discuss implications regarding semileptonic decays B --> X_c l nu and the associated "1/2 versus 3/2" puzzle. Comment: 22 pages, 5 figures; v2: reference added; v3: JHEP journal version (minor modifications)
03/2009;
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[show abstract]
[hide abstract]
ABSTRACT: We compare flavour singlet and non-singlet vector mesons from first principles using lattice QCD. With N_f=2 flavours of light quark, this addresses the omega-rho mass difference. Using maximally twisted-mass lattice QCD, we are able for the first time to determine this mass difference precisely and we compare with experiment. We also discuss omega-rho mixing effects arising within QCD through the u-d quark mass difference. Comment: 12 pages 4 figures
02/2009;
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[show abstract]
[hide abstract]
ABSTRACT: We present results for chiral extrapolations of the mass and decay constants of the rho meson. The data sets used are the nf=2 unquenched gauge configurations generated with twisted mass fermions by the European Twisted Mass Collaboration. We describe a calculation of three decay constants in charmonium and explain why they are required. Comment: 7 pages, 2 figures. Talk given at the XXVI International Symposium on Lattice Field Theory, July 14 - 19 2008, Williamsburg, Virginia, USA
10/2008;
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[show abstract]
[hide abstract]
ABSTRACT: We compute the static-light meson spectrum using two-flavor Wilson twisted mass lattice QCD. We have considered five different values for the light quark mass corresponding to 300 MeV < m_PS < 600 MeV. We have extrapolated our results, to make predictions regarding the spectrum of B and B_s mesons. Comment: 7 pages, 2 figures, talk given at the XXVI International Symposium on Lattice Field Theory, July 14 - 19 2008, Williamsburg, Virginia, USA
08/2008;
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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
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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;
