Publications (235)425.67 Total impact

Article: Charmed Pseudoscalar and Vector Mesons: a Comprehensive QCD SumRule View of Their Decay Constants
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ABSTRACT: In spite of undeniable similarities of the applied techniques, somewhat different challenges are encountered when extracting, from QCD sum rules derived from twopoint correlators of appropriate interpolating heavylight quark currents, the decay constants of charmed mesons of pseudoscalar nature, on the one hand, or of vector nature, on the other hand. This observation justifies a rather careful reassessment of the corresponding results.07/2014;  [Show abstract] [Hide abstract]
ABSTRACT: We present the first unquenched lattice QCD results for the bag parameters controlling the short distance contribution to D meson oscillations in the Standard Model and beyond. We have used the gauge configurations produced by the European Twisted Mass Collaboration with Nf = 2 dynamical quarks, at four lattice spacings and light meson masses in the range 280500 MeV. Renormalization is carried out nonperturbatively with the RIMOM method. The bagparameter results have been used to constrain New Physics effects in DDbar mixing, to put a lower bound to the generic New Physics scale and to constrain offdiagonal squark mass terms for TeVscale Supersymmetry.03/2014;  [Show abstract] [Hide abstract]
ABSTRACT: We present a lattice QCD calculation of the up, down, strange and charm quark masses performed using the gauge configurations produced by the European Twisted Mass Collaboration with Nf = 2 + 1 + 1 dynamical quarks, which include in the sea, besides two light mass degenerate quarks, also the strange and charm quarks with masses close to their physical values. The simulations are based on a unitary setup for the two light quarks and on a mixed action approach for the strange and charm quarks. The analysis uses data at three values of the lattice spacing and pion masses in the range 210  450 MeV, allowing for accurate continuum limit and controlled chiral extrapolation. The quark mass renormalization is carried out nonperturbatively using the RIMOM method. The results for the quark masses converted to the bar{MS} scheme are: mud(2 GeV) = 3.70(17) MeV, ms(2 GeV) = 99.6(4.1) MeV and mc(mc) = 1.348(42) GeV. We obtain also the quark mass ratios ms/mud = 26.66(32) and mc/ms = 11.62(16). By studying the mass splitting between the neutral and charged kaons and using available lattice results for the electromagnetic contributions, we evaluate mu/md = 0.470(56), leading to mu = 2.36(24) MeV and md = 5.03(26) MeV.Nuclear Physics B. 03/2014; 887. 
Dataset: FLAG Review 2011
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ABSTRACT: We present a sumrule calculation of the decay constants of the charmed vector mesons D⁎D⁎ and Ds⁎ from the twopoint correlator of vector currents. First, we show that the perturbative expansion in terms of the pole mass exhibits no sign of convergence whereas the reorganization of this expansion in terms of the MS¯ mass leads to a distinct hierarchy. Second, making use of the operator product expansion in terms of the MS¯ mass, we determine the decay constants of the D⁎D⁎ and Ds⁎ mesons with an emphasis on the uncertainties in these theoretically predicted quantities related both to the input QCD parameters and to the limited accuracy of the method of sum rules. Our results are fD⁎=(252.2±22.3OPE±4syst) MeVfD⁎=(252.2±22.3OPE±4syst) MeV and fDs⁎=(305.5±26.8OPE±5syst) MeV. For the ratios of the vectortopseudoscalar decay constants we report fD⁎/fD=1.221±0.080OPE±0.008systfD⁎/fD=1.221±0.080OPE±0.008syst and fDs⁎/fDs=1.241±0.057OPE±0.007syst.Physics Letters B. 01/2014; 735:12–18.  [Show abstract] [Hide abstract]
ABSTRACT: We study matrix elements of the "chromomagnetic" operator on the lattice. This operator is contained in the strangenesschanging effective Hamiltonian which describes electroweak effects in the Standard Model and beyond. Having dimension 5, the chromomagnetic operator is characterized by a rich pattern of mixing with other operators of equal and lower dimensionality, including also non gauge invariant quantities; it is thus quite a challenge to extract from lattice simulations a clear signal for the hadronic matrix elements of this operator. We compute all relevant mixing coefficients to one loop in lattice perturbation theory; this necessitates calculating both 2point (quarkantiquark) and 3point (gluonquarkantiquark) Green's functions at nonzero quark masses. We use the twisted mass lattice formulation, with Symanzik improved gluon action. For a comprehensive presentation of our results, along with detailed explanations and a more complete list of references, we refer to our forthcoming publication [1].11/2013;  [Show abstract] [Hide abstract]
ABSTRACT: We present a lattice QCD calculation of the pseudoscalar decay constants $f_K$, $f_D$ and $f_{D_s}$ performed by the European Twisted Mass Collaboration with $N_f = 2 + 1 + 1$ dynamical fermions. We simulated at three different values of the lattice spacing, the smallest being approximately $0.06fm$, and with pion masses as small as $210$MeV. Our main results are: $f_{K^+}/f_{\pi^+}=1.183(17)$, $f_{K^+}=154.4(2.1)$MeV, $f_{D_s}=242.1(8.3)$MeV, $f_D=201.9(8.0)$MeV, $f_{D_s}/f_D=1.199(25)$ and $(f_{D_s}/f_D) / (f_K/f_\pi) = 1.005(15)$.11/2013;  [Show abstract] [Hide abstract]
ABSTRACT: We present a lattice QCD determination of the average updown, strange and charm quark masses based on simulations performed by the European Twisted Mass Collaboration with $N_f = 2 + 1 + 1$ dynamical fermions. We simulated at three different values of the lattice spacing, the smallest being approximately $0.06fm$, and with pion masses as small as $210 \text{MeV}$. Our results are: $m_{ud}(2\text{GeV})=3.70(17)\text{MeV}$, $m_s(2\text{GeV})=99.2(3.9)\text{MeV}$, $m_c(m_c)=1.350(49)\text{GeV}$, $m_s/m_{ud}=26.64(30)$ and $m_c/m_s=11.65(12)$.11/2013;  [Show abstract] [Hide abstract]
ABSTRACT: We present a lattice QCD determination of the $b$quark mass and of the $f_{B_s}$ and $f_B$ decay constants performed with $N_f = 2 + 1 + 1$ twisted mass Wilson fermions. We have used simulations at three values of the lattice spacing generated by ETMC with pion masses ranging from 210 to 440 MeV. To obtain physical quantities we performed a combined chiral and continuum limit and an extrapolation in the heavy quark mass from the charm to the $b$quark region using suitable ratios calculated at nearby heavyquark masses having an exactly known static limit. Our results are: $m_b(m_b) = 4.29 (13)$ GeV, $f_B = 196 (9)$ MeV, $f_{B_s} = 235 (9)$ MeV, $f_{B_s} / f_B = 1.201 (25)$, $(f_{B_s}/f_B)/(f_K/f_\pi) = 1.007 (16)$ and $(f_{B_s}/f_B)/(f_{D_s}/f_D) = 1.008 (13)$.11/2013;  [Show abstract] [Hide abstract]
ABSTRACT: We review lattice results related to pion, kaon, D and Bmeson physics with the aim of making them easily accessible to the particle physics community. More specifically, we report on the determination of the lightquark masses, the form factor f+(0), arising in semileptonic K > pi transition at zero momentum transfer, as well as the decay constant ratio fK/fpi of decay constants and its consequences for the CKM matrix elements Vus and Vud. Furthermore, we describe the results obtained on the lattice for some of the lowenergy constants of SU(2)LxSU(2)R and SU(3)LxSU(3)R Chiral Perturbation Theory and review the determination of the BK parameter of neutral kaon mixing. The inclusion of heavyquark quantities significantly expands the FLAG scope with respect to the previous review. Therefore, for this review, we focus on D and Bmeson decay constants, form factors, and mixing parameters, since these are most relevant for the determination of CKM matrix elements and the global CKM unitaritytriangle fit.10/2013; 
Article: Accurate BottomQuark Mass from Borel QCD Sum Rules for the Decay Constants of $B$ and $B_s$ Mesons
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ABSTRACT: We show that in the context of QCD sum rules a strong (anti) correlation between the $b$quark mass $m_b$ and the $B$meson's decay constant $f_B$ emerges: $\delta f_B/f_B\approx 8 \delta m_b/m_b.$ This observation allows us to derive a precise value of $m_b$ from a Borel sum rule for the twopoint correlator of heavylight currents exploiting accurate $f_B$ results from lattice QCD as input: $\bar{m}_b(\bar{m}_b)=(4.247\pm0.034)$ GeV.10/2013;  [Show abstract] [Hide abstract]
ABSTRACT: We present an accurate lattice QCD computation of the bquark mass, the B and Bs decay constants, the Bmixing bagparameters for the full fourfermion operator basis, as well as estimates for \xi and f_{Bq}\sqrt{B_q} extrapolated to the continuum limit and the physical pion mass. We have used Nf = 2 dynamical quark gauge configurations at four values of the lattice spacing generated by ETMC. Extrapolation in the heavy quark mass from the charm to the bottom quark region has been carried out using ratios of physical quantities computed at nearby quark masses, having an exactly known infinite mass limit.10/2013;  [Show abstract] [Hide abstract]
ABSTRACT: We demonstrate that Borel QCD sum rules for heavylight currents entail a very strong correlation between the $b$quark mass $m_b$ and the $B$meson decay constant $f_B,$ that is, $\delta f_B/f_B\approx8\delta m_b/m_b.$ By starting from $f_B$ as input, this observation allows for an accurate sumrule determination of $m_b.$ Employing precise lattice QCD results for $f_B$ in our sumrule study based on the threeloop $O(\alpha_s^2)$ heavylight correlation function implies $\bar{m}_b(\bar{m}_b)=(4.247\pm0.034)$ GeV for the $b$quark $\bar{\rm MS}$ mass.09/2013;  [Show abstract] [Hide abstract]
ABSTRACT: We prove that Borel QCD sum rules for heavy–light currents yield very strong correlations between the bquark mass mb and the Bmeson decay constant fB, namely, δfB/fB≈8δmb/mb. This fact opens the possibility of an accurate sumrule extraction of mb by using fB as input. Combining precise lattice QCD determinations of fB with our sumrule analysis based on the threeloop O(αs2) heavy–light correlation function leads to m̅ b(m̅ b)=(4.247±0.034) GeV.Physical Review D 09/2013; 88(5):056011. · 4.69 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Exploiting recently proposed novel improvements of the techniques used for extracting from QCD sum rules pivotal hadron characteristics, including their systematic errors, we succeed to achieve a conspicuous agreement of the predictions of QCD sum rules for the decay constants $f_B$ and $f_{B_s}$ of the heavy pseudoscalar mesons $B$ and $B_s,$ which before tended to be slightly too large, with corresponding results from lattice QCD. Adopting for the crucial $b$quark $\bar{\rm MS}$ mass the value $\bar{m}_b(\bar{m}_b)=(4.247\pm0.034)$ GeV, we get $f_B=(192.0\pm14.6)$ MeV and $f_{B_s}=(228.0\pm19.8)$ MeV; clearly, this may be also viewed as a determination of the $b$quark mass from sufficiently precise decay constants.08/2013;  [Show abstract] [Hide abstract]
ABSTRACT: We present a lattice QCD computation of the bquark mass, the B and B_s decay constants, the Bmixing bag parameters for the full fourfermion operator basis as well as estimates for \xi and f_{Bq}\sqrt{B_i^{(q)}} extrapolated to the continuum limit and to the physical pion mass. We used Nf = 2 twisted mass Wilson fermions at four values of the lattice spacing with pion masses ranging from 280 to 500 MeV. Extrapolation in the heavy quark mass from the charm to the bottom quark region has been carried out on ratios of physical quantities computed at nearby quark masses, exploiting the fact that they have an exactly known infinite mass limit. Our results are m_b(m_b, \overline{MS)=4.29(12) GeV, f_{Bs}=228(8) MeV, f_{B}=189(8) MeV and f_{Bs}/f_B=1.206(24). Moreover with our estimates for the bagparameters we find \xi=1.225(31), B_1^{(s)}/B_1^{(d)}=1.01(2), f_{Bd}\sqrt{\hat{B}_{1}^{(d)}} = 216(10) MeV and f_{Bs}\sqrt{\hat{B}_{1}^{(s)}} = 262(10) MeV. We also computed the bag parameters for the complete basis of the fourfermion operators which are required in beyond the SM theories. By using these results for the bag parameters we are able to provide a refined Unitarity Triangle analysis, improving the bounds coming from B_{(s)}\bar B_{(s)} mixing constraints on New Physics.08/2013;  Journal of High Energy Physics 07/2013; · 5.62 Impact Factor
 Physical review D: Particles and fields 04/2013; 87(7).
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ABSTRACT: We present a method to evaluate on the lattice the leading isospin breaking effects due to both the small mass difference between the up and down quarks and the QED interaction. Our proposal is applicable in principle to any QCD+QED gauge invariant hadronic observable which can be computed on the lattice. It is based on the expansion of the pathintegral in powers of the small parameters (m_d  m_u)/Lambda_{QCD} and alpha_{em}, where m_f is the renormalized quark mass and alpha_{em} the renormalized fine structure constant. In this paper we discuss in detail the general strategy of the method and the conventional, although arbitrary, separation of QCD from QED isospin breaking corrections. We obtain results for the pion mass splitting, M_{pi+}^2M_{pi0}^2= 1.44(13)(16) x 10^3 MeV^2, for the Dashen's theorem breaking parameter epsilon_{gamma}= 0.79(18)(18), for the light quark masses, [m_d  m_u](MSbar,2 GeV)= 2.39(8)(17) MeV, [m_u / m_d](MSbar,2 GeV)= 0.50(2)(3) and for the flavour symmetry breaking parameters R and Q. We also update our previous results for the QCD isospin breaking corrections to the Kl2 decay rate and for the QCD contribution to the neutronproton mass splitting.Physical review D: Particles and fields 03/2013; 87(11).  [Show abstract] [Hide abstract]
ABSTRACT: We present a precise lattice QCD determination of the bquark mass, of the B and Bs decay constants and first results for the Bmeson bag parameters. For our computation we employ the socalled ratio method and our results benefit from the use of improved interpolating operators for the Bmesons. QCD calculations are performed with Nf = 2 dynamical lightquarks 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 bquark mass, fBs = 234(6) MeV and fB = 197(10) MeV for the Bmeson decay constants, BBs(mb) = 0.90(5) and BB(mb) = 0.87(5) for the Bmeson bag parameters.12/2012;
Publication Stats
3k  Citations  
425.67  Total Impact Points  
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Institutions

2005–2013

Università Degli Studi Roma Tre
 Department of Mathematics and Physics
Roma, Latium, Italy


2011

Austrian Academy of Sciences
 Institut für Hochenergiephysik
Mondsee, Upper Austria, Austria


2010

University of Vienna
 Fakultät für Physik
Wien, Vienna, Austria


1998–2010

Moscow State Textile University
Moskva, Moscow, Russia 
University of Pavia
Ticinum, Lombardy, Italy 
Università degli Studi di Genova
 Department of Physics
Genova, Liguria, Italy


1994–2010

University of Rome Tor Vergata
 Dipartimento di Fisica
Roma, Latium, Italy


1984–2009

INFN  Istituto Nazionale di Fisica Nucleare
Frascati, Latium, Italy


2008

Lomonosov Moscow State University
 Skobeltsyn Institute of Nuclear Physics
Moscow, Moscow, Russia


2003–2005

Sapienza University of Rome
 Department of Physics
Roma, Latium, Italy 
Universität Heidelberg
 Institute of Theoretical Physics
Heidelberg, BadenWuerttemberg, Germany


1990–1994

Università degli Studi di Perugia
 Department of Physics
Perugia, Umbria, Italy


1985

Istituto Superiore di Sanità
Roma, Latium, Italy
