Equation of state in ( 2 + 1 )-flavor QCD Bazavov, A.; Bhattacharya, Tanmoy; DeTar, C. ...
Physical review. D, Particles, fields, gravitation, and cosmology,
11/2014, Letnik:
90, Številka:
9
Journal Article
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We present results for the equation of state in (2 + 1)-flavor QCD using the highly improved staggered quark action and lattices with temporal extent N sub(tau) = 6, 8, 10, and 12. We show that these ...data can be reliably extrapolated to the continuum limit and obtain a number of thermodynamic quantities and the speed of sound in the temperature range 130-400 MeV. We compare our results with previous calculations and provide an analytic parameterization of the pressure, from which other thermodynamic quantities can be calculated, for use in phenomenology. We show that the energy density in the crossover region, 145 MeV < or = T < or = 163 MeV, defined by the chiral transition, is varepsilonc = (0.18-0.5) GeV /fm super(3), i.e., (1.2-3.1) varepsilon sub(nuclear). At high temperatures, we compare our results with resummed and dimensionally reduced perturbation theory calculations. As a byproduct of our analyses, we obtain the values of the scale parameters r sub(0) from the static quark potential and w sub(0) from the gradient flow.
We review lattice results related to pion, kaon, D- and B-meson physics with the aim of making them easily accessible to the particle-physics community. More specifically, we report on the ...determination of the light-quark masses, the form factor \f_+(0)\, arising in the semileptonic \K \rightarrow \pi \ transition at zero momentum transfer, as well as the decay constant ratio \f_K/f_\pi \ and its consequences for the CKM matrix elements \V_{us}\ and \V_{ud}\. Furthermore, we describe the results obtained on the lattice for some of the low-energy constants of \SU(2)_L\times SU(2)_R\ and \SU(3)_L\times SU(3)_R\ Chiral Perturbation Theory. We review the determination of the \B_K\ parameter of neutral kaon mixing as well as the additional four B parameters that arise in theories of physics beyond the Standard Model. The latter quantities are an addition compared to the previous review. For the heavy-quark sector, we provide results for \m_c\ and \m_b\ (also new compared to the previous review), as well as those for D- and B-meson-decay constants, form factors, and mixing parameters. These are the heavy-quark quantities most relevant for the determination of CKM matrix elements and the global CKM unitarity-triangle fit. Finally, we review the status of lattice determinations of the strong coupling constant \\alpha _s\.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We calculate the up-, down-, strange-, charm-, and bottom-quark masses using the MILC highly improved staggered-quark ensembles with four flavors of dynamical quarks. We use ensembles at six lattice ...spacings ranging from a≈0.15 to 0.03 fm and with both physical and unphysical values of the two light and the strange sea-quark masses. We use a new method based on heavy-quark effective theory (HQET) to extract quark masses from heavy-light pseudoscalar meson masses. Combining our analysis with our separate determination of ratios of light-quark masses we present masses of the up, down, strange, charm, and bottom quarks. Our results for the MS¯-renormalized masses are mu(2 GeV)=2.130(41) MeV, md(2 GeV)=4.675(56) MeV, ms(2 GeV)=92.47(69) MeV, mc(3 GeV)=983.7(5.6) MeV, and mc(mc)=1273(10) MeV, with four active flavors; and mb(mb)=4195(14) MeV with five active flavors. We also obtain ratios of quark masses mc/ms=11.783(25), mb/ms=53.94(12), and mb/mc=4.578(8). The result for mc matches the precision of the most precise calculation to date, and the other masses and all quoted ratios are the most precise to date. Moreover, these results are the first with a perturbative accuracy of αs4. As byproducts of our method, we obtain the matrix elements of HQET operators with dimension 4 and 5: Λ¯MRS=555(31) MeV in the minimal renormalon-subtracted (MRS) scheme, μπ2=0.05(22) GeV2, and μG2(mb)=0.38(2) GeV2. The MRS scheme Phys. Rev. D 97, 034503 (2018) is the key new aspect of our method.
All lattice-QCD calculations of the hadronic-vacuum-polarization contribution to the muon's anomalous magnetic moment to date have been performed with degenerate up- and down-quark masses. Here we ...calculate directly the strong-isospin-breaking correction to a_{μ}^{HVP} for the first time with physical values of m_{u} and m_{d} and dynamical u, d, s, and c quarks, thereby removing this important source of systematic uncertainty. We obtain a relative shift to be applied to lattice-QCD results obtained with degenerate light-quark masses of δa_{μ}^{HVP,m_{u}≠m_{d}}=+1.5(7)%, in agreement with estimates from phenomenology.
We report on a scale determination with gradient-flow techniques on the N sub(functionof)=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 radicalt sub(0)/a and w sub(0)/a and their tree-level improvements, radicalt sub(0,imp) and w sub(0,imp), are computed on each ensemble using Symanzik flow and the cloverleaf definition of the energy density E. Using a combination of continuum chiral-perturbation theory and a Taylor-series ansatz for the lattice-spacing and strong-coupling dependence, the results are simultaneously extrapolated to the continuum and interpolated to physical quark masses. We determine the scales (ProQuest: Formulae and/or non-USASCII text omitted)and (ProQuest: Formulae and/or non-USASCII text omitted), where the errors are sums, in quadrature, of statistical and all systematic errors. The precision of w sub(0) and radicalt sub(0) is comparable to or more precise than the best previous estimates, respectively. We then find the continuum mass dependence of radicalt sub(0) and w sub(0), which will be useful for estimating the scales of new ensembles. We also estimate the integrated autocorrelation length of left angle bracketE(t)right angle bracket. For long flow times, the autocorrelation length of left angle bracketEright angle bracket appears to be comparable to that of the topological charge.
We calculate the contribution to the muon anomalous magnetic moment hadronic vacuum polarization from the connected diagrams of up and down quarks, omitting electromagnetism. We employ QCD ...gauge-field configurations with dynamical u, d, s, and c quarks and the physical pion mass, and analyze five ensembles with lattice spacings ranging from a≈0.06 to 0.15 fm. The up- and down-quark masses in our simulations have equal masses ml. We obtain, in this world where all pions have the mass of the π0, 1010aμll(conn.)=637.8(8.8), in agreement with independent lattice-QCD calculations. We then combine this value with published lattice-QCD results for the connected contributions from strange, charm, and bottom quarks, and an estimate of the uncertainty due to the fact that our calculation does not include strong-isospin breaking, electromagnetism, or contributions from quark-disconnected diagrams. Our final result for the total O(α2) hadronic-vacuum polarization to the muon's anomalous magnetic moment is 1010aμHVP,LO=699(15)u,d(1)s,c,b, where the errors are from the light-quark and heavy-quark contributions, respectively. Our result agrees with both ab-initio lattice-QCD calculations and phenomenological determinations from experimental e+e−-scattering data. It is 1.3σ below the "no new physics" value of the hadronic-vacuum-polarization contribution inferred from combining the BNL E821 measurement of aμ with theoretical calculations of the other contributions.
We present a lattice calculation of the electromagnetic (EM) effects on the masses of light pseudoscalar mesons. The simulations employ 2+1 dynamical flavors of asqtad QCD quarks and quenched ...photons. Lattice spacings vary from ≈0.12 fm to ≈0.045 fm. We compute the quantity ε, which parametrizes the corrections to Dashen’s theorem for the K+–K0 EM mass splitting, as well as εK0, which parametrizes the EM contribution to the mass of the K0 itself. An extension of the nonperturbative EM renormalization scheme introduced by the BMW group is used in separating EM effects from isospin-violating quark mass effects. We correct for leading finite-volume effects in our realization of lattice electrodynamics in chiral perturbation theory, and remaining finite-volume errors are relatively small. While electroquenched effects are under control for ε, they are estimated only qualitatively for εK0 and constitute one of the largest sources of uncertainty for that quantity. We find ε=0.78(1)stat(+8−11)syst and εK0=0.035(3)stat(20)syst. We then use these results on 2+1+1 flavor pure QCD highly improved staggered quark (HISQ) ensembles and find mu/md=0.4529(48)stat(+150−67)syst.
This study reports the association of a mutant form of contactin-associated protein-like 2 (CASPR2) and epilepsy, cortical dysplasia, and developmental decay among children in an Old Order Amish ...population. It suggests that mutant CASPR2 causes epilepsy and influences cortical architecture.
This study reports the association of a mutant form of contactin-associated protein-like 2 (CASPR2) and epilepsy, cortical dysplasia, and developmental decay among children in an Old Order Amish population.
Most epileptic disorders can be traced to an abnormality of cortical architecture, channel-mediated currents, neuronal growth and differentiation, or cerebral metabolism.
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In most cases, however, the underlying biologic complexity of epilepsy precludes the identification of the genetic cause, and 65 to 79 percent of recurrent seizure syndromes remain unexplained.
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Microarray analysis of DNA samples can be a powerful tool for revealing a genetic lesion in well-defined families. We have used this approach in Old Order Amish families, some members of which have a clinical and neuropathological phenotype that we designate as the cortical dysplasia–focal epilepsy (CDFE) syndrome. We identified . . .
GM3 synthase (ST3GAL5) is the first biosynthetic enzyme of a- and b-series gangliosides. Patients with GM3 synthase deficiency suffer severe neurological disability and deafness. Eight children (ages ...4.1 ± 2.3 years) homozygous for ST3GAL5 c.694C>T had no detectable GM3 (a-series) or GD3 (b-series) in plasma. Their auditory function was characterized by the absence of middle ear muscle reflexes, distortion product otoacoustic emissions and cochlear microphonics, as well as abnormal auditory brainstem responses and cortical auditory-evoked potentials. In St3gal5(-/-) mice, stereocilia of outer hair cells showed signs of degeneration as early as postnatal Day 3 (P3); thereafter, blebs devoid of actin or tubulin appeared at the region of vestigial kinocilia, suggesting impaired vesicular trafficking. Stereocilia of St3gal5(-/-) inner hair cells were fused by P17, and protein tyrosine phosphatase receptor Q, normally linked to myosin VI at the tapered base of stereocilia, was maldistributed along the cell membrane. B4galnt1(-/-) (GM2 synthase-deficient) mice expressing only GM3 and GD3 gangliosides had normal auditory structure and function. Thus, GM3-dependent membrane microdomains might be essential for the proper organization and maintenance of stereocilia in auditory hair cells.
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