31
31
Sep 22, 2013
09/13
by
C. Bernard; C. DeTar; M. Di Pierro; A. X. El-Khadra; R. T. Evans; E. D. Freeland; E. Gamiz; Steven Gottlieb; U. M. Heller; J. E. Hetrick; A. S. Kronfeld; J. Laiho; L. Levkova; P. B. Mackenzie; M. Okamoto; M. B. Oktay; J. N. Simone; R. Sugar; D. Toussaint; R. S. Van de Water
texts
eye 31
favorite 0
comment 0
Comparisons of lattice-QCD calculations of semileptonic form factors with experimental measurements often display two sets of points, one each for lattice QCD and experiment. Here we propose to display the output of a lattice-QCD analysis as a curve and error band. This is justified, because lattice-QCD results rely in part on fitting, both for the chiral extrapolation and to extend lattice-QCD data over the full physically allowed kinematic domain. To display an error band, correlations in the...
Source: http://arxiv.org/abs/0906.2498v2
3
3.0
Jun 28, 2018
06/18
by
Daping Du; A. X. El-Khadra; Steven Gottlieb; A. S. Kronfeld; J. Laiho; E. Lunghi; R. S. Van de Water; Ran Zhou
texts
eye 3
favorite 0
comment 0
We study the exclusive semileptonic $B$-meson decays $B\to K(\pi)\ell^+\ell^-$, $B\to K(\pi)\nu\bar\nu$, and $B\to\pi\tau\nu$, computing observables in the Standard model using the recent lattice-QCD results for the underlying form factors from the Fermilab Lattice and MILC Collaborations. These processes provide theoretically clean windows into physics beyond the Standard Model because the hadronic uncertainties are now under good control for suitably binned observables. For example, the...
Topics: High Energy Physics - Experiment, High Energy Physics - Lattice, High Energy Physics - Phenomenology
Source: http://arxiv.org/abs/1510.02349
5
5.0
Jun 27, 2018
06/18
by
Fermilab Lattice; MILC Collaborations; :; Jon A. Bailey; A. Bazavov; C. Bernard; C. M. Bouchard; C. DeTar; Daping Du; A. X. El-Khadra; J. Foley; E. D. Freeland; E. Gámiz; Steven Gottlieb; U. M. Heller; J. Komijani; A. S. Kronfeld; J. Laiho; L. Levkova; Yuzhi Liu; P. B. Mackenzie; Y. Meurice; E. T. Neil; Si-Wei Qiu; J. Simone; R. Sugar; D. Toussaint; R. S. Van de Water; Ran Zhou
texts
eye 5
favorite 0
comment 0
We present a lattice-QCD calculation of the $B\to\pi\ell\nu$ semileptonic form factors and a new determination of the CKM matrix element $|V_{ub}|$. We use the MILC asqtad 2+1-flavor lattice configurations at four lattice spacings and light-quark masses down to 1/20 of the physical strange-quark mass. We extrapolate the lattice form factors to the continuum using staggered chiral perturbation theory in the hard-pion and SU(2) limits. We employ a model-independent $z$ parameterization to...
Topics: High Energy Physics - Experiment, High Energy Physics - Phenomenology, High Energy Physics - Lattice
Source: http://arxiv.org/abs/1503.07839
29
29
Sep 22, 2013
09/13
by
C. Aubin; N. H. Christ; C. Dawson; J. Laiho; J. Noaki; S. Li; A. Soni
texts
eye 29
favorite 0
comment 0
We discuss the implementation and properties of the quenched approximation in the calculation of the left-right, strong penguin contributions (i.e. Q_6) to epsilon'/epsilon. The coefficient of the new chiral logarithm, discovered by Golterman and Pallante, which appears at leading order in quenched chiral perturbation theory is evaluated using both the method proposed by those authors and by an improved approach which is free of power divergent corrections. The result implies a large quenching...
Source: http://arxiv.org/abs/hep-lat/0603025v2
30
30
Sep 23, 2013
09/13
by
MILC Collaboration; A. Bazavov; C. Bernard; C. DeTar; X. Du; W. Freeman; Steven Gottlieb; Urs M. Heller; J. E. Hetrick; J. Laiho; L. Levkova; M. B. Oktay; J. Osborn; R. Sugar; D. Toussaint; R. S. Van de Water
texts
eye 30
favorite 0
comment 0
We present the current status of the MILC collaboration's calculations of the properties of the light pseudoscalar meson sector. We use asqtad staggered ensembles with 2+1 dynamical flavors down to $a \approx 0.045$ fm and light quark mass down to 0.05 $m_s$. Here we describe fits to the data using chiral forms from SU(3) chiral perturbation theory, including all staggered taste violations at NLO and the continuum NNLO chiral logarithms. We emphasize issues of convergence of the chiral...
Source: http://arxiv.org/abs/1012.0868v1
45
45
Sep 22, 2013
09/13
by
Jon A. Bailey; C. Bernard; C. DeTar; M. Di Pierro; A. X. El-Khadra; R. T. Evans; E. D. Freeland; E. Gamiz; Steven Gottlieb; U. M. Heller; J. E. Hetrick; A. S. Kronfeld; J. Laiho; L. Levkova; P. B. Mackenzie; M. Okamoto; J. N. Simone; R. Sugar; D. Toussaint; R. S. Van de Water
texts
eye 45
favorite 0
comment 0
We calculate the form factor f_+(q^2) for B-meson semileptonic decay in unquenched lattice QCD with 2+1 flavors of light sea quarks. We use Asqtad-improved staggered light quarks and a Fermilab bottom quark on gauge configurations generated by the MILC Collaboration. We simulate with several light quark masses and at two lattice spacings, and extrapolate to the physical quark mass and continuum limit using heavy-light meson staggered chiral perturbation theory. We then fit the lattice result...
Source: http://arxiv.org/abs/0811.3640v3
3
3.0
Jun 30, 2018
06/18
by
A. Bazavov; C. Bernard; C. M. Bouchard; C. DeTar; D. Du; A. X. El-Khadra; J. Foley; E. D. Freeland; E. Gámiz; Steven Gottlieb; U. M. Heller; J. Kim; J. Komijani; A. S. Kronfeld; J. Laiho; L. Levkova; P. B. Mackenzie; E. T. Neil; J. N. Simone; R. Sugar; D. Toussaint; R. S. Van de Water; R. Zhou
texts
eye 3
favorite 0
comment 0
We compute the leptonic decay constants $f_{D^+}$, $f_{D_s}$, and $f_{K^+}$, and the quark-mass ratios $m_c/m_s$ and $m_s/m_l$ in unquenched lattice QCD using the experimentally determined value of $f_{\pi^+}$ for normalization. We use the MILC highly improved staggered quark (HISQ) ensembles with four dynamical quark flavors---up, down, strange, and charm---and with both physical and unphysical values of the light sea-quark masses. The use of physical pions removes the need for a chiral...
Topics: High Energy Physics - Phenomenology, High Energy Physics - Lattice
Source: http://arxiv.org/abs/1407.3772
5
5.0
Jun 30, 2018
06/18
by
S. Basak; A. Bazavov; C. Bernard; C. DeTar; E. Freeland; J. Foley; Steven Gottlieb; U. M. Heller; J. Komijani; J. Laiho; L. Levkova; J. Osborn; R. L. Sugar; A. Torok; D. Toussaint; R. S. Van de Water; R. Zhou; for the MILC Collaboration
texts
eye 5
favorite 0
comment 0
We report on the MILC Collaboration calculation of electromagnetic effects on light pseudoscalar mesons. The simulations employ asqtad staggered dynamical quarks in QCD plus quenched photons, with lattice spacings varying from 0.12 to 0.06 fm. Finite volume corrections for the MILC realization of lattice electrodynamics have been calculated in chiral perturbation theory and applied to the lattice data. These corrections differ from those calculated by Hayakawa and Uno because our treatment of...
Topics: High Energy Physics - Phenomenology, High Energy Physics - Lattice
Source: http://arxiv.org/abs/1409.7139
2
2.0
Jun 30, 2018
06/18
by
C. C. Chang; C. Bernard; C. M. Bouchard; A. X. El-Khadra; E. D. Freeland; E. Gámiz; A. S. Kronfeld; J. Laiho; R. S. Van de Water
texts
eye 2
favorite 0
comment 0
We present an update on our calculation of the short-distance $D^0$-meson mixing hadronic matrix elements. The analysis is performed on the MILC collaboration's $N_f=2+1$ asqtad configurations. We use asqtad light valence quarks and the Sheikoleslami-Wohlert action with the Fermilab interpretation for the valence charm quark. SU(3), partially quenched, rooted, staggered heavy-meson chiral perturbation theory is used to extrapolate to the chiral-continuum limit. Systematic errors arising from...
Topic: High Energy Physics - Lattice
Source: http://arxiv.org/abs/1411.6086
2
2.0
Jun 30, 2018
06/18
by
J. A. Bailey; A. Bazavov; C. Bernard; C. Bouchard; C. DeTar; D. Du; A. X. El-Khadra; J. Foley; E. D. Freeland; E. Gamiz; Steven Gottlieb; U. M. Heller; A. S. Kronfeld; J. Laiho; L. Levkova; Yuzhi Liu; P. B. Mackenzie; Y. Meurice; E. T. Neil; S. Qiu; J. N. Simone; R. L. Sugar; D. Toussaint; R. S. Van de Water; R. Zhou
texts
eye 2
favorite 0
comment 0
We compute the $B\to\pi\ell\nu$ semileptonic form factors and update the determination of the CKM matrix element $|V_{ub}|$. We use the MILC asqtad ensembles with $N_f=2+1$ sea quarks at four different lattice spacings in the range $a \approx 0.045$~fm to $0.12$~fm. The lattice form factors are extrapolated to the continuum limit using SU(2) staggered chiral perturbation theory in the hard pion limit, followed by an extrapolation in $q^2$ to the full kinematic range using a functional...
Topic: High Energy Physics - Lattice
Source: http://arxiv.org/abs/1411.6038
37
37
Sep 23, 2013
09/13
by
C. Bernard; C. M. Bouchard; A. X. El-Khadra; E. D. Freeland; E. Gámiz; A. S. Kronfeld; J. Laiho; R. S. Van de Water; for the Fermilab-Lattice Collaboration; for the MILC Collaboration
texts
eye 37
favorite 0
comment 0
We give a brief overview and progress report on our lattice QCD calculation of neutral B mixing hadronic matrix elements needed for Standard Model and Beyond the Standard Model physics. Reference [1] contains more details and results.
Source: http://arxiv.org/abs/1111.2968v1
3
3.0
Jun 30, 2018
06/18
by
A. Bazavov; C. Bernard; N. Brown; C. DeTar; J. Foley; Steven Gottlieb; U. M. Heller; J. E. Hetrick; J. Komijani; J. Laiho; L. Levkova; M. Oktay; R. L. Sugar; D. Toussaint; R. S. Van de Water; R. Zhou
texts
eye 3
favorite 0
comment 0
We report on a preliminary scale determination with gradient-flow techniques on the $N_f = 2 + 1 + 1$ HISQ ensembles generated by the MILC collaboration. The ensembles include four lattice spacings, ranging from 0.15 to 0.06 fm, and both physical and unphysical values of the quark masses. The scales $\sqrt{t_0}/a$ and $w_0/a$ are computed using Symanzik flow and the cloverleaf definition of $\langle E \rangle$ on each ensemble. Then both scales and the meson masses $aM_\pi$ and $aM_K$ are...
Topic: High Energy Physics - Lattice
Source: http://arxiv.org/abs/1411.0068
2
2.0
Jun 30, 2018
06/18
by
A. Bazavov; C. Bernard; C. Bouchard; C. DeTar; D. Du; A. X. El-Khadra; J. Foley; E. D. Freeland; E. Gámiz; Steven Gottlieb; U. M. Heller; J. Kim; J. Komijani; A. S. Kronfeld; J. Laiho; L. Levkova; P. B. Mackenzie; E. T. Neil; J. N. Simone; R. L. Sugar; D. Toussaint; R. S. Van de Water; R. Zhou
texts
eye 2
favorite 0
comment 0
We compute the leptonic decay constants $f_{D^+}$, $f_{D_s}$, and $f_{K^+}$, and the quark-mass ratios $m_c/m_s$ and $m_s/m_l$ in unquenched lattice QCD. We use the MILC highly improved staggered quark (HISQ) ensembles with four dynamical quark flavors. Our primary results are $f_{D^+} = 212.6(0.4)({}^{+1.0}_{-1.2})\ \mathrm{MeV}$, $f_{D_s} = 249.0(0.3)({}^{+1.1}_{-1.5})\ \mathrm{MeV}$, and $f_{D_s}/f_{D^+} = 1.1712(10)({}^{+29}_{-32})$, where the errors are statistical and total systematic,...
Topic: High Energy Physics - Lattice
Source: http://arxiv.org/abs/1411.2667
2
2.0
Jun 30, 2018
06/18
by
C. M. Bouchard; E. D. Freeland; C. W. Bernard; C. C. Chang; A. X. El-Khadra; M. E. Gámiz; A. S. Kronfeld; J. Laiho; R. S. Van de Water
texts
eye 2
favorite 0
comment 0
We report on the status of our calculation of the hadronic matrix elements for neutral $B$-meson mixing with asqtad sea and valence light quarks and using the Wilson clover action with the Fermilab interpretation for the $b$ quark. We calculate the matrix elements of all five local operators that contribute to neutral $B$-meson mixing both in and beyond the Standard Model. We use MILC ensembles with $N_f=2+1$ dynamical flavors at four different lattice spacings in the range $a \approx...
Topics: High Energy Physics - Phenomenology, High Energy Physics - Lattice
Source: http://arxiv.org/abs/1412.5097
2
2.0
Jun 29, 2018
06/18
by
E. Gamiz; A. Bazavov; C. Bernard; C. DeTar; D. Du; A. X. El-Khadra; E. D. Freeland; Steven Gottlieb; U. M. Heller; J. Komijani; A. S. Kronfeld; J. Laiho; P. B. Mackenzie; E. T. Neil; T. Primer; J. N. Simone; R. Sugar; D. Toussaint; R. S. Van de Water; Ran Zhou
texts
eye 2
favorite 0
comment 0
We discuss the reduction of errors in the calculation of the form factor $f_+^{K \pi}(0)$ with HISQ fermions on the $N_f=2+1+1$ MILC configurations from increased statistics on some key ensembles, new data on ensembles with lattice spacings down to 0.042 fm and the study of finite-volume effects within staggered ChPT. We also study the implications for the unitarity of the CKM matrix in the first row and for current tensions with leptonic determinations of $\vert V_{us}\vert$.
Topics: High Energy Physics - Phenomenology, High Energy Physics - Lattice, High Energy Physics - Experiment
Source: http://arxiv.org/abs/1611.04118
34
34
Sep 19, 2013
09/13
by
A. Bazavov; C. Bernard; C. DeTar; X. Du; W. Freeman; Steven Gottlieb; Urs M. Heller; J. E. Hetrick; J. Laiho; L. Levkova; M. B. Oktay; J. Osborn; R. Sugar; D. Toussaint; R. S. Van de Water
texts
eye 34
favorite 0
comment 0
We present the status of the MILC collaboration's analysis of the light pseudoscalar meson sector with SU(3) chiral fits. The analysis includes data from new ensembles with smaller lattice spacing, smaller light quark masses and lighter than physical strange quark masses. Our fits include the NNLO chiral logarithms. We present results for decay constants, quark masses, Gasser-Leutwyler low energy constants, and condensates in the two- and three-flavor chiral limits.
Source: http://arxiv.org/abs/0910.3618v2
11
11
Jun 28, 2018
06/18
by
Jon A. Bailey; A. Bazavov; C. Bernard; C. M. Bouchard; C. DeTar; Daping Du; A. X. El-Khadra; J. Foley; E. D. Freeland; E. Gámiz; Steven Gottlieb; U. M. Heller; R. D. Jain; J. Komijani; A. S. Kronfeld; J. Laiho; L. Levkova; Yuzhi Liu; P. B. Mackenzie; Y. Meurice; E. T. Neil; Si-Wei Qiu; J. N. Simone; R. Sugar; D. Toussaint; R. S. Van de Water; Ran Zhou
texts
eye 11
favorite 0
comment 0
We compute the form factors for the $B \to Kl^+l^-$ semileptonic decay process in lattice QCD using gauge-field ensembles with 2+1 flavors of sea quark, generated by the MILC Collaboration. The ensembles span lattice spacings from 0.12 to 0.045 fm and have multiple sea-quark masses to help control the chiral extrapolation. The asqtad improved staggered action is used for the light valence and sea quarks, and the clover action with the Fermilab interpretation is used for the heavy $b$ quark. We...
Topics: High Energy Physics - Phenomenology, High Energy Physics - Lattice
Source: http://arxiv.org/abs/1509.06235
7
7.0
Jun 28, 2018
06/18
by
MILC Collaboration; S. Basak; A. Bazavov; C. Bernard; C. DeTar; E. Freeland; J. Foley; Steven Gottlieb; U. M. Heller; J. Komijani; J. Laiho; L. Levkova; R. Li; J. Osborn; R. L. Sugar; A. Torok; D. Toussaint; R. S. Van de Water; R. Zhou
texts
eye 7
favorite 0
comment 0
For some time, the MILC Collaboration has been studying electromagnetic effects on light mesons. These calculations use fully dynamical QCD, but only quenched photons, which suffices to NLO in XPT. That is, the sea quarks are electrically neutral, while the valence quarks carry charge. For the photons we use the non-compact formalism. We have new results with lattice spacing as small as 0.045 fm and a large range of volumes. We consider how well chiral perturbation theory describes these...
Topics: High Energy Physics - Lattice, High Energy Physics - Phenomenology
Source: http://arxiv.org/abs/1510.04997
2
2.0
Jun 29, 2018
06/18
by
A. Bazavov; C. Bernard; C. M. Bouchard; C. C. Chang; C. DeTar; Daping Du; A. X. El-Khadra; E. D. Freeland; E. Gamiz; Steven Gottlieb; U. M. Heller; A. S. Kronfeld; J. Laiho; P. B. Mackenzie; E. T. Neil; J. Simone; R. Sugar; D. Toussaint; R. S. Van de Water; Ran Zhou
texts
eye 2
favorite 0
comment 0
We calculate---for the first time in three-flavor lattice QCD---the hadronic matrix elements of all five local operators that contribute to neutral $B^0$- and $B_s$-meson mixing in and beyond the Standard Model. We present a complete error budget for each matrix element and also provide the full set of correlations among the matrix elements. We also present the corresponding bag parameters and their correlations, as well as specific combinations of the mixing matrix elements that enter the...
Topics: High Energy Physics - Phenomenology, High Energy Physics - Lattice
Source: http://arxiv.org/abs/1602.03560
3
3.0
Jun 30, 2018
06/18
by
Jon A. Bailey; A. Bazavov; C. Bernard; C. M. Bouchard; C. DeTar; Daping Du; A. X. El-Khadra; J. Foley; E. D. Freeland; E. Gamiz; Steven Gottlieb; U. M. Heller; A. S. Kronfeld; J. Laiho; L. Levkova; P. B. Mackenzie; E. T. Neil; Si-Wei Qiu; J. Simone; R. Sugar; D. Toussaint; R. S. Van de Water; Ran Zhou
texts
eye 3
favorite 0
comment 0
We compute the zero-recoil form factor for the semileptonic decay $\bar{B}^0\to D^{*+}\ell^-\bar{\nu}$ (and modes related by isospin and charge conjugation) using lattice QCD with three flavors of sea quarks. We use an improved staggered action for the light valence and sea quarks (the MILC \asqtad\ configurations), and the Fermilab action for the heavy quarks. Our calculations incorporate higher statistics, finer lattice spacings, and lighter quark masses than our 2008 work. As a byproduct of...
Topics: High Energy Physics - Phenomenology, High Energy Physics - Lattice
Source: http://arxiv.org/abs/1403.0635
3
3.0
Jun 29, 2018
06/18
by
J. Komijani; A. Bazavov; C. Bernard; N. Brambilla; N. Brown; C. DeTar; D. Du; A. X. El-Khadra; E. D. Freeland; E. Gámiz; Steven Gottlieb; U. M. Heller; A. S. Kronfeld; J. Laiho; P. B. Mackenzie; C. Monahan; Heechang Na; E. T. Neil; J. N. Simone; R. L. Sugar; D. Toussaint; A. Vairo; R. S. Van de Water
texts
eye 3
favorite 0
comment 0
We present a progress report on our calculation of the decay constants $f_B$ and $f_{B_s}$ from lattice-QCD simulations with highly-improved staggered quarks. Simulations are carried out with several heavy valence-quark masses on $(2+1+1)$-flavor ensembles that include charm sea quarks. We include data at six lattice spacings and several light sea-quark masses, including an approximately physical-mass ensemble at all but the smallest lattice spacing, 0.03 fm. This range of parameters provides...
Topics: High Energy Physics - Phenomenology, High Energy Physics - Lattice
Source: http://arxiv.org/abs/1611.07411
3
3.0
Jun 28, 2018
06/18
by
Fermilab Lattice; MILC Collaborations; :; A. Bazavov; C. Bernard; C. Bouchard; N. Brown; C. DeTar; D. Du; A. X. El-Khadra; E. D. Freeland; E. Gámiz; Steven Gottlieb; U. M. Heller; J. Komijani; A. S. Kronfeld; J. Laiho; L. Levkova; P. B. Mackenzie; C. Monahan; T. Primer; Heechang Na; E. T. Neil; J. N. Simone; R. L. Sugar; D. Toussaint; R. S. Van de Water; R. Zhou
texts
eye 3
favorite 0
comment 0
We give a progress report on a project aimed at a high-precision calculation of the decay constants $f_B$ and $f_{B_s}$ from simulations with HISQ heavy and light valence and sea quarks. Calculations are carried out with several heavy valence-quark masses on ensembles with 2+1+1 flavors of HISQ sea quarks at five lattice spacings and several light sea-quark mass ratios $m_{ud}/m_s$, including approximately physical sea-quark masses. This range of parameters provides excellent control of the...
Topic: High Energy Physics - Lattice
Source: http://arxiv.org/abs/1511.02294
3
3.0
Jun 29, 2018
06/18
by
MILC Collaboration; S. Basak; A. Bazavov; C. Bernard; C. DeTar; E. Freeland; J. Foley; Steven Gottlieb; U. M. Heller; J. Komijani; J. Laiho; L. Levkova; J. Osborn; R. L. Sugar; A. Torok; D. Toussaint; R. S. Van de Water; R. Zhou
texts
eye 3
favorite 0
comment 0
The MILC Collaboration has completed production running of electromagnetic effects on light mesons using asqtad improved staggered quarks. In these calculations, we use quenched photons in the noncompact formalism. We study four lattice spacings from $\approx\!0.12\:$fm to $\approx\!0.045\:$fm. To study finite-volume effects, we used six spatial lattice sizes $L/a=12$, 16, 20, 28, 40, and 48, at $a\!\approx\!0.12\:$fm. We update our preliminary values for the correction to Dashen's theorem...
Topics: High Energy Physics - Phenomenology, High Energy Physics - Lattice
Source: http://arxiv.org/abs/1606.01228
44
44
Sep 21, 2013
09/13
by
A. Bazavov; C. Bernard; C. DeTar; X. Du; W. Freeman; Steven Gottlieb; U. M. Heller; J. E. Hetrick; J. Laiho; L. Levkova; M. B. Oktay; R. Sugar; D. Toussaint; R. S. Van de Water
texts
eye 44
favorite 0
comment 0
In the light pseudoscalar sector, we study rooted staggered chiral perturbation theory in the two-flavor case. The pion mass and decay constant are calculated through NLO for a partially-quenched theory. In the limit where the strange quark mass is large compared to the light quark masses and the taste splittings, we show that the SU(2) staggered chiral theory emerges from the SU(3) staggered chiral theory, as expected. Explicit relations between SU(2) and SU(3) low energy constants and...
Source: http://arxiv.org/abs/1011.1792v1
2
2.0
Jun 29, 2018
06/18
by
J. Laiho; S. Bassler; D. Coumbe; D. Du; J. T. Neelakanta
texts
eye 2
favorite 0
comment 0
We study the nonperturbative formulation of quantum gravity defined via Euclidean dynamical triangulations (EDT) in an attempt to make contact with Weinberg's asymptotic safety scenario. We find that a fine-tuning is necessary in order to recover semiclassical behavior. Such a fine-tuning is generally associated with the breaking of a target symmetry by the lattice regulator; in this case we identify the target symmetry as the general coordinate invariance of the theory. After introducing and...
Topics: High Energy Physics - Theory, High Energy Physics - Lattice
Source: http://arxiv.org/abs/1604.02745
2
2.0
Jun 30, 2018
06/18
by
A. Bazavov; C. Bernard; C. Bouchard; C. DeTar; D. Du; A. X. El-Khadra; J. Foley; E. D. Freeland; E. Gámiz; Steven Gottlieb; U. M. Heller; J. Kim; J. Komijani; A. S. Kronfeld; J. Laiho; L. Levkova; P. B. Mackenzie; D. Mohler; E. T. Neil; M. B. Oktay; S. Qiu; J. N. Simone; R. L. Sugar; D. Toussaint; R. S. Van de Water; R. Zhou
texts
eye 2
favorite 0
comment 0
We present a study of the $D$ and $B$ leptonic decay constants on the MILC $N_f=2+1$ asqtad gauge ensembles using asqtad-improved staggered light quarks and clover heavy quarks in the Fermilab interpretation. Our previous analysis \cite{Bazavov:2011aa} computed the decay constants at lattice spacings $a \approx 0.14, 0.11$ and $0.083$ fm. We have extended the simulations to finer $a \approx 0.058$ and $0.043$ fm lattice spacings, and have also increased statistics; this allows us to address...
Topic: High Energy Physics - Lattice
Source: http://arxiv.org/abs/1403.6796
51
51
Sep 23, 2013
09/13
by
A. Bazavov; C. Bernard; C. DeTar; Steven Gottlieb; U. M. Heller; J. E. Hetrick; J. Laiho; L. Levkova; P. B. Mackenzie; M. B. Oktay; R. Sugar; D. Toussaint; R. S. Van de Water
texts
eye 51
favorite 0
comment 0
Dramatic progress has been made over the last decade in the numerical study of quantum chromodynamics (QCD) through the use of improved formulations of QCD on the lattice (improved actions), the development of new algorithms and the rapid increase in computing power available to lattice gauge theorists. In this article we describe simulations of full QCD using the improved staggered quark formalism, ``asqtad'' fermions. These simulations were carried out with two degenerate flavors of light...
Source: http://arxiv.org/abs/0903.3598v2
42
42
Sep 21, 2013
09/13
by
C. Aubin; J. Laiho; S. Li; M. F. Lin
texts
eye 42
favorite 0
comment 0
We calculate results for K to pi and K to 0 matrix elements to next-to-leading order in 2+1 flavor partially quenched chiral perturbation theory. Results are presented for both the Delta I=1/2 and 3/2 channels, for chiral operators corresponding to current-current, gluonic penguin, and electroweak penguin 4-quark operators. These formulas are useful for studying the chiral behavior of currently available 2+1 flavor lattice QCD results, from which the low energy constants of the chiral effective...
Source: http://arxiv.org/abs/0808.3264v2
40
40
Sep 20, 2013
09/13
by
A. Bazavov; C. Bernard; C. M. Bouchard; C. DeTar; M. Di Pierro; A. X. El-Khadra; R. T. Evans; E. D. Freeland; E. Gamiz; Steven Gottlieb; U. M. Heller; J. E. Hetrick; R. Jain; A. S. Kronfeld; J. Laiho; L. Levkova; P. B. Mackenzie; E. T. Neil; M. B. Oktay; J. N. Simone; R. Sugar; D. Toussaint; R. S. Van de Water
texts
eye 40
favorite 0
comment 0
We study SU(3)-breaking effects in the neutral B_d-\bar B_d and B_s-\bar B_s systems with unquenched N_f=2+1 lattice QCD. We calculate the relevant matrix elements on the MILC collaboration's gauge configurations with asqtad-improved staggered sea quarks. For the valence light-quarks (u, d, and s) we use the asqtad action, while for b quarks we use the Fermilab action. We obtain \xi=f_{B_s}\sqrt{B_{B_s}}/f_{B_d}\sqrt{B_{B_d}}=1.268+-0.063. We also present results for the ratio of bag parameters...
Source: http://arxiv.org/abs/1205.7013v1
59
59
Sep 23, 2013
09/13
by
A. Bazavov; C. Bernard; C. DeTar; W. Freeman; Steven Gottlieb; U. M. Heller; J. E. Hetrick; J. Laiho; L. Levkova; J. Osborn; R. Sugar; D. Toussaint
texts
eye 59
favorite 0
comment 0
We report on recent progress in employing the Highly Improved Staggered Quark (HISQ) action introduced by the HPQCD/UKQCD collaboration in simulations with dynamical fermions. The HISQ action is an order $a^2$ Symanzik-improved action with further suppressed taste symmetry violations. The improvement in taste symmetry is achieved by introducing Fat7 smearing of the original gauge links and reunitarization (projection to an element of U(3) or SU(3)) followed by Asq-type smearing. Major...
Source: http://arxiv.org/abs/0903.0874v1
2
2.0
Jun 30, 2018
06/18
by
J. Laiho; S. Bassler; D. Coumbe; D. Du; J. T. Neelakanta
texts
eye 2
favorite 0
comment 0
We study a formulation of lattice gravity defined via Euclidean dynamical triangulations (EDT). After fine-tuning a non-trivial local measure term we find evidence that four-dimensional, semi-classical geometries are recovered at long distance scales in the continuum limit. Furthermore, we find that the spectral dimension at short distance scales is consistent with 3/2, a value that is also observed in the causal dynamical triangulation (CDT) approach to quantum gravity.
Topic: High Energy Physics - Theory
Source: http://arxiv.org/abs/1701.06829
39
39
Sep 23, 2013
09/13
by
MILC Collaboration; A. Bazavov; C. Bernard; C. DeTar; W. Freeman; Steven Gottlieb; U. M. Heller; J. E. Hetrick; J. Kim; J. Laiho; L. Levkova; M. Lightman; M. Oktay; J. Osborn; R. L. Sugar; D. Toussaint; R. S. Van de Water
texts
eye 39
favorite 0
comment 0
We fit lattice-QCD data for light-pseudoscalar masses and decay constants, from HISQ configurations generated by MILC, to SU(3) staggered chiral perturbation theory. At present such fits have rather high values of chi^2/d.o.f., possibly due to the lack of ensembles with lighter-than-physical sea strange-quark masses. We propose solutions to this problem for future work. We also perform simple linear interpolations near the physical point on two ensembles with different lattice spacings, and...
Source: http://arxiv.org/abs/1111.4314v1
32
32
Sep 24, 2013
09/13
by
E. T. Neil; Jon A. Bailey; A. Bazavov; C. Bernard; C. M. Bouchard; C. DeTar; M. Di Pierro; A. X. El-Khadra; R. T. Evans; E. Freeland; E. Gamiz; Steven Gottlieb; U. M. Heller; J. E. Hetrick; R. Jain; A. S. Kronfeld; J. Laiho; L. Levkova; P. B. Mackenzie; M. B. Oktay; J. N. Simone; R. Sugar; D. Toussaint; R. S. Van de Water; for the Fermilab Lattice Collaboration; for the MILC Collaboration
texts
eye 32
favorite 0
comment 0
We give an update on simulation results for the decay constants f_B, f_{B_s}, f_D and f_{D_s}. These decay constants are important for precision tests of the standard model, in particular entering as inputs to the global CKM unitarity triangle fit. The results presented here make use of the MILC (2+1)-flavor asqtad ensembles, with heavy quarks incorporated using the clover action with the Fermilab method. Partially quenched, staggered chiral perturbation theory is used to extract the decay...
Source: http://arxiv.org/abs/1112.3978v1
37
37
Sep 23, 2013
09/13
by
A. Bazavov; C. Bernard; C. Bouchard; C. DeTar; D. Du; A. X. El-Khadra; J. Foley; E. D. Freeland; E. Gamiz; Steven Gottlieb; U. M. Heller; J. E. Hetrick; J. Kim; A. S. Kronfeld; J. Laiho; L. Levkova; M. Lightman; P. B. Mackenzie; E. T. Neil; M. Oktay; J. N. Simone; R. L. Sugar; D. Toussaint; R. S. Van de Water; R. Zhou; for the Fermilab Lattice Collaboration; for the MILC Collaboration
texts
eye 37
favorite 0
comment 0
We present our methods to fit the two point correlators for light, strange, and charmed pseudoscalar meson physics with the highly improved staggered quark (HISQ) action. We make use of the least-squares fit including the full covariance matrix of the correlators and including Gaussian constraints on some parameters. We fit the correlators on a variety of the HISQ ensembles. The lattice spacing ranges from 0.15 fm down to 0.06 fm. The light sea quark mass ranges from 0.2 times the strange quark...
Source: http://arxiv.org/abs/1212.0613v1
42
42
Sep 19, 2013
09/13
by
A. Bazavov; C. Bernard; C. DeTar; X. Du; W. Freeman; Steven Gottlieb; Urs M. Heller; J. E. Hetrick; J. Laiho; L. Levkova; M. B. Oktay; J. Osborn; R. Sugar; D. Toussaint; R. S. Van de Water
texts
eye 42
favorite 0
comment 0
We present the latest preliminary results of the MILC collaboration's analysis of the light pseudoscalar meson sector. The analysis includes data from new ensembles with smaller lattice spacings, smaller light quark masses and lighter-than-physical strange quark masses. Both SU(2) and SU(3) chiral fits, including NNLO chiral logarithms, are shown. We give results for decay constants, quark masses, Gasser-Leutwyler low energy constants, and condensates in the two- and three-flavor chiral limits.
Source: http://arxiv.org/abs/0910.2966v1
104
104
Sep 17, 2013
09/13
by
C. Bernard; C. DeTar; M. Di Pierro; A. X. El-Khadra; R. T. Evans; E. D. Freeland; E. Gámiz; Steven Gottlieb; U. M. Heller; J. E. Hetrick; A. S. Kronfeld; J. Laiho; L. Levkova; P. B. Mackenzie; J. N. Simone; R. Sugar; D. Toussaint; R. S. Van de Water
texts
eye 104
favorite 0
comment 0
We report the non-perturbative tuning of parameters--- kappa_c, kappa_b, and kappa_crit ---that determine the heavy-quark mass in the Fermilab action. This requires the computation of the masses of Ds^(*) and Bs^(*) mesons comprised of a Fermilab heavy quark and a staggered light quark. Additionally, we report the hyperfine splittings for Ds and Bs mesons as a cross-check of our simulation and analysis methods. We find a splitting of 145 +/- 15 MeV for the Ds system and 40 +/- 9 MeV for the Bs...
Source: http://arxiv.org/abs/1003.1937v2
67
67
Sep 23, 2013
09/13
by
C. Bernard; C. DeTar; M. Di Pierro; A. X. El-Khadra; R. T. Evans; E. D. Freeland; E. Gamiz; Steven Gottlieb; U. M. Heller; J. E. Hetrick; A. S. Kronfeld; J. Laiho; L. Levkova; P. B. Mackenzie; J. Simone; R. Sugar; D. Toussaint; R. S. Van de Water
texts
eye 67
favorite 0
comment 0
We present an update of our calculations of the decay constants of the D, D_s, B, and B_s mesons in unquenched 2+1 flavor QCD. We use the MILC library of improved staggered gauge ensembles at lattice spacings 0.09, 0.12, and 0.15 fm, clover heavy quarks with the Fermilab normalizations, and improved staggered light valence quarks.
Source: http://arxiv.org/abs/0904.1895v1
35
35
Sep 22, 2013
09/13
by
MILC collaboration; A. Bazavov; C. Bernard; C. DeTar; W. Freeman; Steven Gottlieb; U. M. Heller; J. E. Hetrick; J. Laiho; L. Levkova; M. Oktay; J. Osborn; R. L. Sugar; D. Toussaint; R. S. Van de Water
texts
eye 35
favorite 0
comment 0
We study the lattice spacing dependence, or scaling, of physical quantities using the highly improved staggered quark (HISQ) action introduced by the HPQCD/UKQCD collaboration, comparing our results to similar simulations with the asqtad fermion action. Results are based on calculations with lattice spacings approximately 0.15, 0.12 and 0.09 fm, using four flavors of dynamical HISQ quarks. The strange and charm quark masses are near their physical values, and the light-quark mass is set to 0.2...
Source: http://arxiv.org/abs/1004.0342v2
8
8.0
Jun 27, 2018
06/18
by
Fermilab Lattice; MILC Collaborations; :; Jon A. Bailey; A. Bazavov; C. Bernard; C. M. Bouchard; C. DeTar; Daping Du; A. X. El-Khadra; J. Foley; E. D. Freeland; E. Gámiz; Steven Gottlieb; U. M. Heller; J. Komijani; A. S. Kronfeld; J. Laiho; L. Levkova; P. B. Mackenzie; E. T. Neil; Si-Wei Qiu; J. Simone; R. Sugar; D. Toussaint; R. S. Van de Water; Ran Zhou
texts
eye 8
favorite 0
comment 0
We present the first unquenched lattice-QCD calculation of the hadronic form factors for the exclusive decay $\overline{B} \rightarrow D \ell \overline{\nu}$ at nonzero recoil. We carry out numerical simulations on fourteen ensembles of gauge-field configurations generated with 2+1 flavors of asqtad-improved staggered sea quarks. The ensembles encompass a wide range of lattice spacings (approximately 0.045 to 0.12 fm) and ratios of light (up and down) to strange sea-quark masses ranging from...
Topic: High Energy Physics - Lattice
Source: http://arxiv.org/abs/1503.07237
35
35
Sep 21, 2013
09/13
by
J. Laiho; D. Coumbe
texts
eye 35
favorite 0
comment 0
We calculate the spectral dimension for nonperturbative quantum gravity defined via Euclidean dynamical triangulations. We find that it runs from a value of ~3/2 at short distance to ~4 at large distance scales, similar to results from causal dynamical triangulations. We argue that the short distance value of 3/2 for the spectral dimension may resolve the tension between asymptotic safety and the holographic principle.
Source: http://arxiv.org/abs/1104.5505v2
10
10.0
Jun 28, 2018
06/18
by
Jon A. Bailey; A. Bazavov; C. Bernard; C. M. Bouchard; C. DeTar; Daping Du; A. X. El-Khadra; E. D. Freeland; E. Gamiz; Steven Gottlieb; U. M. Heller; A. S. Kronfeld; J. Laiho; L. Levkova; Yuzhi Liu; E. Lunghi; P. B. Mackenzie; Y. Meurice; E. Neil; Si-Wei Qiu; J. N. Simone; R. Sugar; D. Toussaint; R. S. Van de Water; Ran Zhou
texts
eye 10
favorite 0
comment 0
The rare decay $B\to\pi\ell^+\ell^-$ arises from $b\to d$ flavor-changing neutral currents and could be sensitive to physics beyond the Standard Model. Here, we present the first $ab$-$initio$ QCD calculation of the $B\to\pi$ tensor form factor $f_T$. Together with the vector and scalar form factors $f_+$ and $f_0$ from our companion work [J. A. Bailey $et~al.$, Phys. Rev. D 92, 014024 (2015)], these parameterize the hadronic contribution to $B\to\pi$ semileptonic decays in any extension of the...
Topics: High Energy Physics - Phenomenology, High Energy Physics - Lattice
Source: http://arxiv.org/abs/1507.01618
48
48
Sep 24, 2013
09/13
by
C. M. Bouchard; E. D. Freeland; C. Bernard; A. X. El-Khadra; E. Gamiz; A. S. Kronfeld; J. Laiho; R. S. Van de Water
texts
eye 48
favorite 0
comment 0
We report on the status of our lattice-QCD calculation of the hadronic contribution to $B_d^0$ and $B^0_s$ mixing, with 2+1 flavors of dynamical sea quarks. Preliminary results for hadronic mixing matrix elements are given for a basis of five four-quark, dimension-six, $\Delta B=2$ mixing operators that spans the space of all possible hadronic mixing contributions in the Standard Model and beyond. At the intermediate stage of analysis reported on in this work, our errors are competitive with...
Source: http://arxiv.org/abs/1112.5642v2
43
43
Sep 22, 2013
09/13
by
A. Bazavov; C. Bernard; C. Bouchard; C. DeTar; D. Du; A. X. El-Khadra; J. Foley; E. D. Freeland; E. Gamiz; Steven Gottlieb; U. M. Heller; J. E. Hetrick; J. Kim; A. S. Kronfeld; J. Laiho; L. Levkova; M. Lightman; P. B. Mackenzie; E. T. Neil; M. Oktay; J. N. Simone; R. L. Sugar; D. Toussaint; R. S. Van de Water; R. Zhou; for the Fermilab Lattice Collaboration; for the MILC Collaboration
texts
eye 43
favorite 0
comment 0
We present preliminary results for light, strange and charmed pseudoscalar meson physics from simulations using four flavors of dynamical quarks with the highly improved staggered quark (HISQ) action. These simulations include lattice spacings ranging from 0.15 to 0.06 fm, and sea-quark masses both above and at their physical value. The major results are charm meson decay constants f_D, f_{D_s} and f_{D_s}/f_D and ratios of quark masses. This talk will focus on our procedures for finding the...
Source: http://arxiv.org/abs/1210.8431v1
43
43
Sep 17, 2013
09/13
by
Jon A. Bailey; A. Bazavov; C. Bernard; C. Bouchard; C. DeTar; A. X. El-Khadra; E. D. Freeland; W. Freeman; E. Gamiz; Steven Gottlieb; U. M. Heller; J. E. Hetrick; A. S. Kronfeld; J. Laiho; L. Levkova; P. B. Mackenzie; M. B. Oktay; M. Di Pierro; J. N. Simone; R. Sugar; D. Toussaint; R. S. Van de Water
texts
eye 43
favorite 0
comment 0
Lattice calculations of the form factors for the charm semileptonic decays D to K l nu and D to pi l nu provide inputs to direct determinations of the CKM matrix elements |V(cs)| and |V(cd)| and can be designed to validate calculations of the form factors for the bottom semileptonic decays B to pi l nu and B to K l l-bar. We are using Fermilab charm (bottom) quarks and asqtad staggered light quarks on the 2+1 flavor asqtad MILC ensembles to calculate the charm (bottom) form factors. We outline...
Source: http://arxiv.org/abs/0912.0214v1
37
37
Sep 21, 2013
09/13
by
S. Basak; A. Bazavov; C. Bernard; C. DeTar; E. Freeland; W. Freeman; J. Foley; Steven Gottlieb; U. M. Heller; J. E. Hetrick; J. Laiho; L. Levkova; M. Oktay; J. Osborn; R. L. Sugar; A. Torok; D. Toussaint; R. S. Van de Water; R. Zhou
texts
eye 37
favorite 0
comment 0
We report on the calculation by the MILC Collaboration of the electromagnetic effects on kaon and pion masses. These masses are computed in QCD with dynamical (asqtad staggered) quarks plus quenched photons at three lattice spacings varying from 0.12 to 0.06 fm. The masses are fit to staggered chiral perturbation theory with NLO electromagnetic terms, as well as analytic terms at higher order. We extrapolate the results to physical light-quark masses and to the continuum limit. At the current...
Source: http://arxiv.org/abs/1301.7137v1
48
48
Sep 19, 2013
09/13
by
The MILC Collaboration; S. Basak; A. Bazavov; C. Bernard; C. DeTar; W. Freeman; Steven Gottlieb; U. M. Heller; J. E. Hetrick; J. Laiho; L. Levkova; J. Osborn; R. Sugar; D. Toussaint
texts
eye 48
favorite 0
comment 0
We present our new results for the QCD equation of state at nonzero chemical potential at N_t=6 and compare them with N_t=4. We use the Taylor expansion method with terms up to sixth order in simulations with 2+1 flavors of improved asqtad quarks along a line of constant physics with m_l=0.1 m_s and approximately physical strange quark mass m_s.
Source: http://arxiv.org/abs/0910.0276v1
97
97
Sep 17, 2013
09/13
by
A. Bazavov; C. Bernard; C. DeTar; E. D. Freeland; E. Gamiz; Steven Gottlieb; U. M. Heller; J. E. Hetrick; A. X. El-Khadra; A. S. Kronfeld; J. Laiho; L. Levkova; P. B. Mackenzie; M. B. Oktay; M. Di Pierro; J. N. Simone; R. Sugar; D. Toussaint; R. S. Van de Water
texts
eye 97
favorite 0
comment 0
We present the leptonic decay constants fDs and fD+ computed on the MILC collaboration's 2+1 flavor asqtad gauge ensembles. We use clover heavy quarks with the Fermilab interpretation and improved staggered light quarks. The simultaneous chiral and continuum extrapolation, which determines both decay constants, includes partially-quenched lattice results at lattice spacings a ~ 0:09, 0:12 and 0:15 fm. We have made several recent improvements in our analysis: a) we include terms in the fit...
Source: http://arxiv.org/abs/0912.5221v1
54
54
Sep 23, 2013
09/13
by
A. Bazavov; C. Bernard; C. M. Bouchard; C. DeTar; M. Di Pierro; A. X. El-Khadra; R. T. Evans; E. D. Freeland; E. Gamiz; Steven Gottlieb; U. M. Heller; J. E. Hetrick; R. Jain; A. S. Kronfeld; J. Laiho; L. Levkova; P. B. Mackenzie; E. T. Neil; M. B. Oktay; J. N. Simone; R. Sugar; D. Toussaint; R. S. Van de Water
texts
eye 54
favorite 0
comment 0
We calculate the leptonic decay constants of B_{(s)} and D_{(s)} mesons in lattice QCD using staggered light quarks and Fermilab bottom and charm quarks. We compute the heavy-light meson correlation functions on the MILC asqtad-improved staggered gauge configurations which include the effects of three light dynamical sea quarks. We simulate with several values of the light valence- and sea-quark masses (down to ~m_s/10) and at three lattice spacings (a ~ 0.15, 0.12, and 0.09 fm) and extrapolate...
Source: http://arxiv.org/abs/1112.3051v1
5
5.0
Jun 27, 2018
06/18
by
MILC Collaboration; A. Bazavov; C. Bernard; N. Brown; C. DeTar; J. Foley; Steven Gottlieb; U. M. Heller; J. Komijani; J. Laiho; L. Levkova; R. L. Sugar; D. Toussaint; R. S. Van de Water
texts
eye 5
favorite 0
comment 0
We report on a scale determination with gradient-flow techniques on the $N_f=2+1+1$ highly improved staggered quark ensembles generated by the MILC Collaboration. The ensembles include four lattice spacings, ranging from approximately 0.15 to 0.06 fm, and both physical and unphysical values of the quark masses. The scales $\sqrt{t_0}/a$ and $w_0/a$ and their tree-level improvements, $\sqrt{t_{0,{\rm imp}}}$ and $w_{0,{\rm imp}}$, are computed on each ensemble using Symanzik flow and the...
Topic: High Energy Physics - Lattice
Source: http://arxiv.org/abs/1503.02769
39
39
Sep 21, 2013
09/13
by
C. Bernard; C. DeTar; M. Di Pierro; A. X. El-Khadra; R. T. Evans; E. D. Freeland; E. Gamiz; Steven Gottlieb; U. M. Heller; J. E. Hetrick; A. S. Kronfeld; J. Laiho; L. Levkova; P. B. Mackenzie; M. Okamoto; J. Simone; R. Sugar; D. Toussaint; R. S. Van de Water
texts
eye 39
favorite 0
comment 0
We present the first lattice QCD calculation of the form factor for B-> D* l nu with three flavors of sea quarks. We use an improved staggered action for the light valence and sea quarks (the MILC configurations), and the Fermilab action for the heavy quarks. The form factor is computed at zero recoil using a new double ratio method that yields the form factor more directly than the previous Fermilab method. Other improvements over the previous calculation include the use of much lighter...
Source: http://arxiv.org/abs/0808.2519v2
