The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Ulfg Meisner - One of the best experts on this subject based on the ideXlab platform.
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density dependent effective baryon baryon interaction from chiral three baryon forces
Nuclear Physics, 2017Co-Authors: Stefan Petschauer, J Haidenbauer, Ulfg Meisner, N Kaiser, W WeiseAbstract:Abstract A density-dependent effective potential for the baryon–baryon interaction in the presence of the (hyper)nuclear medium is constructed, based on the leading (irreducible) three-baryon forces derived within SU(3) chiral effective field theory. We evaluate the contributions from three classes: contact terms, one-pion exchange and two-pion exchange. In the strangeness-zero sector we recover the known result for the in-medium nucleon–nucleon interaction. Explicit expressions for the Λ N in-medium potential in (asymmetric) nuclear matter are presented. Our results are suitable for implementation into calculations of (hyper)nuclear matter. In order to estimate the low-energy constants of the leading three-baryon forces we introduce the decuplet Baryons as explicit degrees of freedom and construct the relevant terms in the minimal non-relativistic Lagrangian. With these, the constants are estimated through decuplet saturation. Utilizing this approximation we provide numerical results for the effect of the three-body force in symmetric nuclear matter and pure neutron matter on the Λ N interaction. A moderate repulsion that increases with density is found in comparison to the free Λ N interaction.
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baryon electric dipole moments from strong cp violation
Journal of High Energy Physics, 2012Co-Authors: Ulfg MeisnerAbstract:The electric dipole form factors and moments of the ground state Baryons are calcu- lated in chiral perturbation theory at next-to-leading order. We show that the baryon electric dipole form factors at this order depend only on two combinations of low-energy constants. We also de- rive various relations that are free of unknown low-energy constants. We use recent lattice QCD data to calculate all baryon EDMs. In particular, we find dn = 2:9 0:9 and dp = 1:1 1:1 in units of 10 16 e 0 cm. Finite volume corrections to the electric dipole moments are also worked out. We show that for a precision extraction from lattice QCD data, the next-to-leading order terms have to be accounted for.
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predictions for the strangeness s 3 and 4 baryon baryon interactions in chiral effective field theory
Physics Letters B, 2010Co-Authors: J Haidenbauer, Ulfg MeisnerAbstract:Abstract The leading order strangeness S = − 3 and −4 baryon–baryon interactions are analyzed within chiral effective field theory. The chiral potentials consist of contact terms without derivatives and of one-pseudoscalar-meson exchanges. Assuming SU ( 3 ) flavor symmetry those contact terms and the couplings of the pseudoscalar mesons to the Baryons are related to the corresponding quantities of the S = − 1 hyperon–nucleon channels. Specifically, the values of the pertinent five low-energy constants related to the contact terms are already fixed from our preceding study of the ΛN and ΣN systems and thus genuine predictions for the ΞΛ, ΞΣ, and ΞΞ interactions can be made. Strong attraction is found in some of the S = − 3 and −4 channels, suggesting the possible existence of bound states.
Charles W Danforth - One of the best experts on this subject based on the ideXlab platform.
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characterizing the circumgalactic medium of nearby galaxies with hst cos and hst stis absorption line spectroscopy
The Astrophysical Journal, 2013Co-Authors: John T Stocke, Brian A Keeney, Charles W Danforth, Michael J Shull, Cynthia S Froning, J Green, Steven V Penton, Blair D SavageAbstract:The circumgalactic medium (CGM) of late-type galaxies is characterized using UV spectroscopy of 11 targeted QSO/galaxy pairs at z ≤ 0.02 with the Hubble Space Telescope Cosmic Origins Spectrograph (COS) and ~60 serendipitous absorber/galaxy pairs at z ≤ 0.2 with the Space Telescope Imaging Spectrograph. CGM warm cloud properties are derived, including volume filling factors of 3%-5%, cloud sizes of 0.1-30 kpc, masses of 10-108 M ☉, and metallicities of ~0.1-1 Z ☉. Almost all warm CGM clouds within 0.5 R vir are metal-bearing and many have velocities consistent with being bound, "galactic fountain" clouds. For galaxies with L 0.1 L*, the total mass in these warm CGM clouds approaches 1010 M ☉, ~10%-15% of the total Baryons in massive spirals and comparable to the Baryons in their parent galaxy disks. This leaves 50% of massive spiral-galaxy Baryons "missing." Dwarfs (<0.1 L*) have smaller area covering factors and warm CGM masses (≤5% baryon fraction), suggesting that many of their warm clouds escape. Constant warm cloud internal pressures as a function of impact parameter (P/k ~ 10 cm–3 K) support the inference that previous COS detections of broad, shallow O VI and Lyα absorptions are of an extensive (~400-600 kpc), hot (T ≈ 106 K), intra-cloud gas which is very massive (≥1011 M ☉). While the warm CGM clouds cannot account for all the "missing Baryons" in spirals, the hot intra-group gas can, and could account for ~20% of the cosmic baryon census at z ~ 0 if this hot gas is ubiquitous among spiral groups.
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characterizing the circumgalactic medium of nearby galaxies with hst cos and hst stis absorption line spectroscopy
arXiv: Cosmology and Nongalactic Astrophysics, 2012Co-Authors: John T Stocke, Brian A Keeney, Charles W Danforth, Michael J Shull, Cynthia S Froning, J Green, Steven V Penton, Blair D SavageAbstract:The Circumgalactic Medium (CGM) of late-type galaxies is characterized using UV spectroscopy of 11 targeted QSO/galaxy pairs at z 0.1 L*, the total mass in these warm CGM clouds approaches 1e10 solar masses, ~10-15% of the total Baryons in massive spirals and comparable to the Baryons in their parent galaxy disks. This leaves >50% of massive spiral-galaxy Baryons "missing". Dwarfs ( 1e11 solar masses). While the warm CGM clouds cannot account for all the "missing Baryons" in spirals, the hot intra-group gas can, and could account for ~20% of the cosmic baryon census at z ~ 0 if this hot gas is ubiquitous among spiral groups.
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the baryon census in a multiphase intergalactic medium 30 of the Baryons may still be missing
The Astrophysical Journal, 2012Co-Authors: Michael J Shull, Britton D Smith, Charles W DanforthAbstract:Although galaxies, groups, and clusters contain {approx}10% of the Baryons, many more reside in the photoionized and shocked-heated intergalactic medium (IGM) and in the circumgalactic medium (CGM). We update the baryon census in the (H I) Ly{alpha} forest and warm-hot IGM (WHIM) at 10{sup 5-6} K traced by O VI {lambda}1032, 1038 absorption. From Enzo cosmological simulations of heating, cooling, and metal transport, we improve the H I and O VI baryon surveys using spatially averaged corrections for metallicity (Z/Z {sub Sun }) and ionization fractions (f {sub HI}, f {sub OVI}). Statistically, the O VI correction product correlates with column density, (Z/Z {sub Sun })f {sub OVI} Almost-Equal-To (0.015)(N {sub OVI}/10{sup 14} cm{sup -2}){sup 0.70}, with an N {sub OVI}-weighted mean of 0.01, which doubles previous estimates of WHIM baryon content. We also update the Ly{alpha} forest contribution to baryon density out to z = 0.4, correcting for the (1 + z){sup 3} increase in absorber density, the (1 + z){sup 4.4} rise in photoionizing background, and cosmological proper length dl/dz. We find substantial baryon fractions in the photoionized Ly{alpha} forest (28% {+-} 11%) and WHIM traced by O VI and broad-Ly{alpha} absorbers (25% {+-} 8%). The collapsed phasemore » (galaxies, groups, clusters, CGM) contains 18% {+-} 4%, leaving an apparent baryon shortfall of 29% {+-} 13%. Our simulations suggest that {approx}15% reside in hotter WHIM (T {>=} 10{sup 6} K). Additional Baryons could be detected in weaker Ly{alpha} and O VI absorbers. Further progress requires higher-precision baryon surveys of weak absorbers, down to minimum column densities N {sub HI} {>=} 10{sup 12.0} cm{sup -2}, N {sub OVI} {>=} 10{sup 12.5} cm{sup -2}, N {sub OVII} {>=} 10{sup 14.5} cm{sup -2}, using high signal-to-noise data from high-resolution UV and X-ray spectrographs.« less
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the baryon census in a multiphase intergalactic medium 30 of the Baryons may still be missing
arXiv: Cosmology and Nongalactic Astrophysics, 2011Co-Authors: Michael J Shull, Britton D Smith, Charles W DanforthAbstract:For low-redshift cosmology and galaxy formation rates, it is important to account for all the Baryons synthesized in the Big Bang. Although galaxies and clusters contain 10% of the Baryons, many more reside in the photoionized Lyman-alpha forest and shocked-heated warm-hot intergalactic medium (WHIM) at T = 10^5 to 10^7 K. Current tracers of WHIM at 10^5 to 10^6 K include the O VI 1032, 1038 absorption lines, together with broad Lyman-alpha absorbers (BLAs) and EUV/X-ray absorption lines from Ne VIII, O VII, and O VIII. We improve the O VI baryon surveys with corrections for oxygen metallicity (Z/Zsun) and O VI ionization fraction (f_OVI) using cosmological simulations of heating, cooling, and metal transport in a density-temperature structured medium. Statistically, their product correlates with column density, (Z/Zsun)(f_OVI) = (0.015)(N_OVI/10^{14} cm^-2)^0.70. The N_OVI-weighted mean is 0.01, which doubles previous estimates of WHIM baryon content. We also reanalyze H I data from the Hubble Space Telescope, applying redshift corrections for absorber density, photoionizing background, and proper length, dl/dz. We find substantial baryon fractions in the photoionized Lya forest (28 +/- 11%), O VI/BLA-traced WHIM (25 +/- 8%), and collapsed phase (18 +/- 4%) in galaxies, groups, clusters, and circumgalactic gas. The baryon shortfall is 29 +/- 13%, which may be detected in X-ray absorbers from hotter WHIM or in weaker Lya and O VI absorbers. Further progress will require higher-precision baryon surveys of weak absorbers at column densities N_HI > 10^{12.0} cm^-2, N_OVI > 10^{12.5} cm^-2, and N_OVII > 10^{14.5} cm^-2, with moderate-resolution UV and X-ray spectrographs.
Michael J Shull - One of the best experts on this subject based on the ideXlab platform.
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characterizing the circumgalactic medium of nearby galaxies with hst cos and hst stis absorption line spectroscopy
The Astrophysical Journal, 2013Co-Authors: John T Stocke, Brian A Keeney, Charles W Danforth, Michael J Shull, Cynthia S Froning, J Green, Steven V Penton, Blair D SavageAbstract:The circumgalactic medium (CGM) of late-type galaxies is characterized using UV spectroscopy of 11 targeted QSO/galaxy pairs at z ≤ 0.02 with the Hubble Space Telescope Cosmic Origins Spectrograph (COS) and ~60 serendipitous absorber/galaxy pairs at z ≤ 0.2 with the Space Telescope Imaging Spectrograph. CGM warm cloud properties are derived, including volume filling factors of 3%-5%, cloud sizes of 0.1-30 kpc, masses of 10-108 M ☉, and metallicities of ~0.1-1 Z ☉. Almost all warm CGM clouds within 0.5 R vir are metal-bearing and many have velocities consistent with being bound, "galactic fountain" clouds. For galaxies with L 0.1 L*, the total mass in these warm CGM clouds approaches 1010 M ☉, ~10%-15% of the total Baryons in massive spirals and comparable to the Baryons in their parent galaxy disks. This leaves 50% of massive spiral-galaxy Baryons "missing." Dwarfs (<0.1 L*) have smaller area covering factors and warm CGM masses (≤5% baryon fraction), suggesting that many of their warm clouds escape. Constant warm cloud internal pressures as a function of impact parameter (P/k ~ 10 cm–3 K) support the inference that previous COS detections of broad, shallow O VI and Lyα absorptions are of an extensive (~400-600 kpc), hot (T ≈ 106 K), intra-cloud gas which is very massive (≥1011 M ☉). While the warm CGM clouds cannot account for all the "missing Baryons" in spirals, the hot intra-group gas can, and could account for ~20% of the cosmic baryon census at z ~ 0 if this hot gas is ubiquitous among spiral groups.
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characterizing the circumgalactic medium of nearby galaxies with hst cos and hst stis absorption line spectroscopy
arXiv: Cosmology and Nongalactic Astrophysics, 2012Co-Authors: John T Stocke, Brian A Keeney, Charles W Danforth, Michael J Shull, Cynthia S Froning, J Green, Steven V Penton, Blair D SavageAbstract:The Circumgalactic Medium (CGM) of late-type galaxies is characterized using UV spectroscopy of 11 targeted QSO/galaxy pairs at z 0.1 L*, the total mass in these warm CGM clouds approaches 1e10 solar masses, ~10-15% of the total Baryons in massive spirals and comparable to the Baryons in their parent galaxy disks. This leaves >50% of massive spiral-galaxy Baryons "missing". Dwarfs ( 1e11 solar masses). While the warm CGM clouds cannot account for all the "missing Baryons" in spirals, the hot intra-group gas can, and could account for ~20% of the cosmic baryon census at z ~ 0 if this hot gas is ubiquitous among spiral groups.
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the baryon census in a multiphase intergalactic medium 30 of the Baryons may still be missing
The Astrophysical Journal, 2012Co-Authors: Michael J Shull, Britton D Smith, Charles W DanforthAbstract:Although galaxies, groups, and clusters contain {approx}10% of the Baryons, many more reside in the photoionized and shocked-heated intergalactic medium (IGM) and in the circumgalactic medium (CGM). We update the baryon census in the (H I) Ly{alpha} forest and warm-hot IGM (WHIM) at 10{sup 5-6} K traced by O VI {lambda}1032, 1038 absorption. From Enzo cosmological simulations of heating, cooling, and metal transport, we improve the H I and O VI baryon surveys using spatially averaged corrections for metallicity (Z/Z {sub Sun }) and ionization fractions (f {sub HI}, f {sub OVI}). Statistically, the O VI correction product correlates with column density, (Z/Z {sub Sun })f {sub OVI} Almost-Equal-To (0.015)(N {sub OVI}/10{sup 14} cm{sup -2}){sup 0.70}, with an N {sub OVI}-weighted mean of 0.01, which doubles previous estimates of WHIM baryon content. We also update the Ly{alpha} forest contribution to baryon density out to z = 0.4, correcting for the (1 + z){sup 3} increase in absorber density, the (1 + z){sup 4.4} rise in photoionizing background, and cosmological proper length dl/dz. We find substantial baryon fractions in the photoionized Ly{alpha} forest (28% {+-} 11%) and WHIM traced by O VI and broad-Ly{alpha} absorbers (25% {+-} 8%). The collapsed phasemore » (galaxies, groups, clusters, CGM) contains 18% {+-} 4%, leaving an apparent baryon shortfall of 29% {+-} 13%. Our simulations suggest that {approx}15% reside in hotter WHIM (T {>=} 10{sup 6} K). Additional Baryons could be detected in weaker Ly{alpha} and O VI absorbers. Further progress requires higher-precision baryon surveys of weak absorbers, down to minimum column densities N {sub HI} {>=} 10{sup 12.0} cm{sup -2}, N {sub OVI} {>=} 10{sup 12.5} cm{sup -2}, N {sub OVII} {>=} 10{sup 14.5} cm{sup -2}, using high signal-to-noise data from high-resolution UV and X-ray spectrographs.« less
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the baryon census in a multiphase intergalactic medium 30 of the Baryons may still be missing
arXiv: Cosmology and Nongalactic Astrophysics, 2011Co-Authors: Michael J Shull, Britton D Smith, Charles W DanforthAbstract:For low-redshift cosmology and galaxy formation rates, it is important to account for all the Baryons synthesized in the Big Bang. Although galaxies and clusters contain 10% of the Baryons, many more reside in the photoionized Lyman-alpha forest and shocked-heated warm-hot intergalactic medium (WHIM) at T = 10^5 to 10^7 K. Current tracers of WHIM at 10^5 to 10^6 K include the O VI 1032, 1038 absorption lines, together with broad Lyman-alpha absorbers (BLAs) and EUV/X-ray absorption lines from Ne VIII, O VII, and O VIII. We improve the O VI baryon surveys with corrections for oxygen metallicity (Z/Zsun) and O VI ionization fraction (f_OVI) using cosmological simulations of heating, cooling, and metal transport in a density-temperature structured medium. Statistically, their product correlates with column density, (Z/Zsun)(f_OVI) = (0.015)(N_OVI/10^{14} cm^-2)^0.70. The N_OVI-weighted mean is 0.01, which doubles previous estimates of WHIM baryon content. We also reanalyze H I data from the Hubble Space Telescope, applying redshift corrections for absorber density, photoionizing background, and proper length, dl/dz. We find substantial baryon fractions in the photoionized Lya forest (28 +/- 11%), O VI/BLA-traced WHIM (25 +/- 8%), and collapsed phase (18 +/- 4%) in galaxies, groups, clusters, and circumgalactic gas. The baryon shortfall is 29 +/- 13%, which may be detected in X-ray absorbers from hotter WHIM or in weaker Lya and O VI absorbers. Further progress will require higher-precision baryon surveys of weak absorbers at column densities N_HI > 10^{12.0} cm^-2, N_OVI > 10^{12.5} cm^-2, and N_OVII > 10^{14.5} cm^-2, with moderate-resolution UV and X-ray spectrographs.
D Blaschke - One of the best experts on this subject based on the ideXlab platform.
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a unified quark nuclear matter equation of state from the cluster virial expansion within the generalized beth uhlenbeck approach
European Physical Journal A, 2021Co-Authors: Nielsuwe F Bastian, D BlaschkeAbstract:We consider a cluster expansion for strongly correlated quark matter where the clusters are Baryons with spectral properties that are described within the generalized Beth–Uhlenbeck approach by a medium dependent phase shift. We employ a simple ansatz for the phase shift which describes an on-shell bound state with an effective mass and models the continuum by an anti-bound state located at the mass of the three-quark continuum threshold, so that the Levinson theorem is fulfilled by construction. The quark and baryon interactions are accounted for by the coupling to scalar and vector meson mean fields modelled by density functionals. At increasing density and temperature, due to the different medium-dependence of quark and baryon masses, the Mott dissociation of Baryons occurs and its contributions to the thermodynamics vanish. It is demonstrated on this simple example that this unified approach to quark-hadron matter is capable of describing crossover as well as first order phase transition behaviour in the phase diagram with a critical endpoint. Changing the meson mean field, the case of a “crossover all over” in the phase diagram is also obtained.
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a unified quark nuclear matter equation of state from the cluster virial expansion within the generalized beth uhlenbeck approach
arXiv: Nuclear Theory, 2018Co-Authors: Nielsuwe F Bastian, D BlaschkeAbstract:We consider a cluster expansion for strongly correlated quark matter where the clusters are Baryons with spectral properties that are described within the generalized Beth-Uhlenbeck approach by a medium dependent phase shift. We employ a simple ansatz for the phase shift which fulfils the Levinson theorem by describing an on-shell bound state with an effective mass and models the continuum by an anti-bound state located at the mass of the three-quark threshold. The quark and baryon interactions are accounted for by the coupling to scalar and vector meson mean fields modelled by density functionals. At increasing density and temperature, due to the different medium-dependence of quark and baryon masses, the Mott dissociation of Baryons occurs and the nuclear cluster contributions to the thermodynamics vanish. It is demonstrated on this simple example that this unified approach to quark-nuclear matter is capable of describing crossover as well as first order phase transition behaviour in the phase diagram with a critical endpoint. Changing the meson mean field, the case of a "crossover all over" in the phase diagram is also obtained.
Atsushi Hosaka - One of the best experts on this subject based on the ideXlab platform.
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a qcd sum rule calculation for p wave bottom Baryons
2015Co-Authors: Qiang Mao, Huaxing Chen, Wei Chen, Atsushi Hosaka, Xiang Liu, Shilin Zhu, Jparc BranchAbstract:We study the P-wave bottom Baryons using the method of QCD sum rule and heavy quark effective theory. Our results suggest thatb(5912) 0 andb(5920) 0 can be well described by the baryon doublet (¯F,1,1,�), and they belong to the SU(3) ¯F multiplets of J P = 1/2 − and 3/2 − . Their SU(3) flavor partners, �b(1/2 − ) andb(3/2 − ), have masses 6.06 ± 0.13 GeV and 6.07 ± 0.13 GeV, respectively, with mass splitting 9 ± 4 MeV. The results obtained using baryon doublet (¯F,1,0,�) are similar and also consistent with the experimental data. We also study the SU(3) 6F multiplets by using the baryon multiplets (6F,0,1,�), (6F,1,0,�) and (6F,2,1,�), and our results suggest that the P-wave bottom Baryonsb, � ' and b have (averaged) masses about 6.0 GeV, 6.2 GeV and 6.4 GeV, respectively.
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qcd sum rule calculation for p wave bottom Baryons
Physical Review D, 2015Co-Authors: Qiang Mao, Huaxing Chen, Wei Chen, Atsushi Hosaka, Xiang Liu, Shilin ZhuAbstract:We study the P-wave bottom Baryons using the method of QCD sum rule and heavy quark effective theory. Our results suggest that Lambda(b) (5912)(0) and Lambda(b) (5920)(0) can be well described by the baryon doublet [(3) over bar (F), 1, 1, rho], and they belong to the SU(3) IF multiplets of J(P) = 1/2(-) and 3/2(-). Their SU(3) flavor partners, Xi(b)(1/2(-)) and Xi(b) (3/2(-)), have masses 6.06 +/- 0.13 GeV and 6.07 +/- 0.13 GeV, respectively, with mass splitting 9 * 4 McV. The results obtained using baryon doublet [(3) over bar (F), 1, 0, lambda] are similar and also consistent with the experimental data. We also study the SU(3) 6(F) multiplets by using the baryon multiplets [6(F), 0, 1, lambda], [6(F), 1, 0, rho] and [6(F), 2, 1, lambda], and our results suggest that the P-wave bottom Baryons Sigma(b), Xi(b)' and Omega(b) have (averaged) masses of about 6.0 GeV, 6.2 GeV and 6.4 GeV, respectively.
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spectrum of heavy Baryons in the quark model
Physical Review D, 2015Co-Authors: T Yoshida, Atsushi Hosaka, Emiko Hiyama, Makoto Oka, Katsunori SadatoAbstract:Single- and double- heavy Baryons are studied in the constituent quark model. The model Hamiltonian is chosen as a standard one with two exceptions : (1) The color-Coulomb term depend on quark masses, and (2) an antisymmetric $LS$ force is introduced. Model parameters are fixed by the strange baryon spectra, $\Lambda$ and $\Sigma$ Baryons. The masses of the observed charmed and bottomed Baryons are, then, fairly well reproduced. Our focus is on the low-lying negative-parity states, in which the heavy Baryons show specific excitation modes reflecting the mass differences of heavy and light quarks. By changing quark masses from the SU(3) limit to the strange quark mass, further to the charm and bottom quark masses, we demonstrate that the spectra change from the SU(3) symmetry patterns to the heavy quark symmetry ones.
