DSpace Collection:
http://hdl.handle.net/2445/19703
Mon, 27 May 2019 13:06:15 GMT2019-05-27T13:06:15ZDisentangling the Dynamical Origin of P11 Nucleon Resonances
http://hdl.handle.net/2445/133443
Title: Disentangling the Dynamical Origin of P11 Nucleon Resonances
Author: Suzuki, N.; Juliá-Díaz, Bruno; Kamano, H.; Lee, T. S. H.; Matsuyama, A.; Sato, T.
Abstract: We show that two almost degenerate poles near the π Δ threshold and the next higher mass pole in the P 11 partial wave of π N scattering evolve from a single bare state through its coupling with π N , η N , and π π N reaction channels. This finding provides new information on understanding the dynamical origins of the Roper N ∗ ( 1440 ) and N ∗ ( 1710 ) resonances listed by Particle Data Group. Our results for the resonance poles in other π N partial waves are also presented.Mon, 20 May 2019 10:31:10 GMThttp://hdl.handle.net/2445/1334432019-05-20T10:31:10ZHyperon-Nucleon Interactions from Quantum Chromodynamics and the Composition of Dense Nuclear Matter
http://hdl.handle.net/2445/133355
Title: Hyperon-Nucleon Interactions from Quantum Chromodynamics and the Composition of Dense Nuclear Matter
Author: Beane, Silas R.; Chang, Emmanuel; Cohen, S. D.; Detmold, William; Lin, H. W.; Luu, Thomas C.; Orginos, Kostas; Parreño García, Assumpta; Savage, Martin J; Walker-Loud, André; NPLQCD Collaboration
Abstract: The low-energy n Σ − interactions determine, in part, the role of the strange quark in dense matter, such as that found in astrophysical environments. The scattering phase shifts for this system are obtained from a numerical evaluation of the QCD path integral using the technique of lattice QCD. Our calculations, performed at a pion mass of m π ∼ 389 MeV in two large lattice volumes and at one lattice spacing, are extrapolated to the physical pion mass using effective field theory. The interactions determined from lattice QCD are consistent with those extracted from hyperon-nucleon experimental data within uncertainties and strengthen model-dependent theoretical arguments that the strange quark is a crucial component of dense nuclear matter.Fri, 17 May 2019 12:00:17 GMThttp://hdl.handle.net/2445/1333552019-05-17T12:00:17ZDetermining Triple Gauge Boson Couplings from Higgs Data
http://hdl.handle.net/2445/133267
Title: Determining Triple Gauge Boson Couplings from Higgs Data
Author: Corbett, Tyler; Éboli, O. J. P.; González Fraile, Juan; González García, Ma. Concepción
Abstract: In the framework of effective Lagrangians with the S U ( 2 ) L × U ( 1 ) Y symmetry linearly realized, modifications of the couplings of the Higgs field to the electroweak gauge bosons are related to anomalous triple gauge couplings (TGCs). Here, we show that the analysis of the latest Higgs boson production data at the LHC and Tevatron give rise to strong bounds on TGCs that are complementary to those from direct TGC analysis. We present the constraints on TGCs obtained by combining all available data on direct TGC studies and on Higgs production analysis.Thu, 16 May 2019 10:37:00 GMThttp://hdl.handle.net/2445/1332672019-05-16T10:37:00ZMild Quasilocal Non-Gaussianity as a Signature of Modified Gravity During Inflation
http://hdl.handle.net/2445/133021
Title: Mild Quasilocal Non-Gaussianity as a Signature of Modified Gravity During Inflation
Author: Bartolo, Nicola; Cannone, Dario; Jiménez, Raúl (Jiménez Tellado); Matarrese, Sabino; Verde, Licia
Abstract: We show that modifications of Einstein gravity during inflation could leave potentially measurable imprints on cosmological observables in the form of non-Gaussian perturbations. This is due to the fact that these modifications appear in the form of an extra field that could have nontrivial interactions with the inflaton. We show it explicitly for the case R + α R 2 , where nearly scale-invariant non-Gaussianity at the level of f NL ≈ − ( 1 to 30 ) can be obtained, in a quasilocal configuration.Mon, 13 May 2019 10:07:32 GMThttp://hdl.handle.net/2445/1330212019-05-13T10:07:32ZPossible Role of Gamma Ray Bursts on Life Extinction in the Universe
http://hdl.handle.net/2445/133018
Title: Possible Role of Gamma Ray Bursts on Life Extinction in the Universe
Author: Tsvi; Jiménez, Raúl (Jiménez Tellado)
Abstract: As a copious source of gamma rays, a nearby galactic gamma ray burst (GRB) can be a threat to life. Using recent determinations of the rate of GRBs, their luminosity function, and properties of their host galaxies, we estimate the probability that a life-threatening (lethal) GRB would take place. Amongst the different kinds of GRBs, long ones are most dangerous. There is a very good chance (but no certainty) that at least one lethal GRB took place during the past 5 gigayears close enough to Earth as to significantly damage life. There is a 50% chance that such a lethal GRB took place during the last 500 × 1 0 6 years , causing one of the major mass extinction events. Assuming that a similar level of radiation would be lethal to life on other exoplanets hosting life, we explore the potential effects of GRBs to life elsewhere in the Galaxy and the Universe. We find that the probability of a lethal GRB is much larger in the inner Milky Way (95% within a radius of 4 kpc from the galactic center), making it inhospitable to life. Only at the outskirts of the Milky Way, at more than 10 kpc from the galactic center, does this probability drop below 50%. When considering the Universe as a whole, the safest environments for life (similar to the one on Earth) are the lowest density regions in the outskirts of large galaxies, and life can exist in only ≈ 10 % of galaxies. Remarkably, a cosmological constant is essential for such systems to exist. Furthermore, because of both the higher GRB rate and galaxies being smaller, life as it exists on Earth could not take place at z > 0.5 . Early life forms must have been much more resilient to radiation.Mon, 13 May 2019 09:41:02 GMThttp://hdl.handle.net/2445/1330182019-05-13T09:41:02ZMagnetic moments of light nuclei from Lattice Quantum Chromodynamics
http://hdl.handle.net/2445/133000
Title: Magnetic moments of light nuclei from Lattice Quantum Chromodynamics
Author: Beane, Silas R.; Chang, Emmanuel; Cohen, S. D.; Detmold, William; Lin, H. W.; Orginos, Kostas; Parreño García, Assumpta; Savage, M. J.; Tiburzi, Brian C.; NPLQCD Collaboration
Abstract: We present the results of lattice QCD calculations of the magnetic moments of the lightest nuclei, the deuteron, the triton, and 3 He , along with those of the neutron and proton. These calculations, performed at quark masses corresponding to m π ∼ 800 MeV , reveal that the structure of these nuclei at unphysically heavy quark masses closely resembles that at the physical quark masses. In particular, we find that the magnetic moment of 3 He differs only slightly from that of a free neutron, as is the case in nature, indicating that the shell-model configuration of two spin-paired protons and a valence neutron captures its dominant structure. Similarly a shell-model-like moment is found for the triton, μ 3 H ∼ μ p . The deuteron magnetic moment is found to be equal to the nucleon isoscalar moment within the uncertainties of the calculations. Furthermore, deviations from the Schmidt limits are also found to be similar to those in nature for these nuclei. These findings suggest that at least some nuclei at these unphysical quark masses are describable by a phenomenological nuclear shell model.Fri, 10 May 2019 13:45:32 GMThttp://hdl.handle.net/2445/1330002019-05-10T13:45:32ZStandard Model False Vacuum Inflation: Correlating the Tensor-to-Scalar Ratio to the Top Quark and Higgs Boson masses
http://hdl.handle.net/2445/132977
Title: Standard Model False Vacuum Inflation: Correlating the Tensor-to-Scalar Ratio to the Top Quark and Higgs Boson masses
Author: Masina, Isabella; Notari, Alessio
Abstract: For a narrow band of values of the top quark and Higgs boson masses, the standard model Higgs potential develops a false minimum at energies of about 10 16 GeV , where primordial inflation could have started in a cold metastable state. A graceful exit to a radiation-dominated era is provided, e.g., by scalar-tensor gravity models. We pointed out that if inflation happened in this false minimum, the Higgs boson mass has to be in the range 126.0 ± 3.5 GeV , where ATLAS and CMS subsequently reported excesses of events. Here we show that for these values of the Higgs boson mass, the inflationary gravitational wave background has be discovered with a tensor-to-scalar ratio at hand of future experiments. We suggest that combining cosmological observations with measurements of the top quark and Higgs boson masses represent a further test of the hypothesis that the standard model false minimum was the source of inflation in the universe.Fri, 10 May 2019 12:49:43 GMThttp://hdl.handle.net/2445/1329772019-05-10T12:49:43ZLongitudinal Coherence in a Holographic Model of Asymmetric Collisions
http://hdl.handle.net/2445/132923
Title: Longitudinal Coherence in a Holographic Model of Asymmetric Collisions
Author: Casalderrey Solana, Jorge; Heller, Michal P.; Mateos, David (Mateos Solé); van der Schee, Wilke
Abstract: As a model of the longitudinal structure in heavy ion collisions, we simulate gravitational shock wave collisions in anti-de Sitter space in which each shock is composed of multiple constituents. We find that all constituents act coherently, and their separation leaves no imprint on the resulting plasma, when this separation is ≲ 0.26 / T hyd , with T hyd the temperature of the plasma at the time when hydrodynamics first becomes applicable. In particular, the center-of-mass of the plasma coincides with the center-of-mass of all the constituents participating in the collision, as opposed to the center-of-mass of the individual collisions. We discuss the implications for nucleus-nucleus and proton-nucleus collisions.Thu, 09 May 2019 14:01:53 GMThttp://hdl.handle.net/2445/1329232019-05-09T14:01:53ZEvolution and End Point of the Black String Instability: Large D Solution
http://hdl.handle.net/2445/132865
Title: Evolution and End Point of the Black String Instability: Large D Solution
Author: Emparan García de Salazar, Roberto A.; Suzuki, Ryotaku; Tanabe, Kentaro
Abstract: We derive a simple set of nonlinear, ( 1 + 1 ) -dimensional partial differential equations that describe the dynamical evolution of black strings and branes to leading order in the expansion in the inverse of the number of dimensions D . These equations are easily solved numerically. Their solution shows that thin enough black strings are unstable to developing inhomogeneities along their length, and at late times they asymptote to stable nonuniform black strings. This proves an earlier conjecture about the end point of the instability of black strings in a large enough number of dimensions. If the initial black string is very thin, the final configuration is highly nonuniform and resembles a periodic array of localized black holes joined by short necks. We also present the equations that describe the nonlinear dynamics of anti-de Sitter black branes at large D .Wed, 08 May 2019 15:26:20 GMThttp://hdl.handle.net/2445/1328652019-05-08T15:26:20ZAb initio Calculation of the np→dγ Radiative Capture Process
http://hdl.handle.net/2445/132862
Title: Ab initio Calculation of the np→dγ Radiative Capture Process
Author: Beane, Silas R.; Chang, Emmanuel; Detmold, William; Orginos, Kostas; Parreño García, Assumpta; Savage, Martin J.; Tiburzi, Brian C.; NPLQCD Collaboration
Abstract: Lattice QCD calculations of two-nucleon systems are used to isolate the short-distance two-body electromagnetic contributions to the radiative capture process n p → d γ , and the photo-disintegration processes γ ( * ) d → n p . In nuclear potential models, such contributions are described by phenomenological meson-exchange currents, while in the present work, they are determined directly from the quark and gluon interactions of QCD. Calculations of neutron-proton energy levels in multiple background magnetic fields are performed at two values of the quark masses, corresponding to pion masses of m π ∼ 450 and 806 MeV, and are combined with pionless nuclear effective field theory to determine the amplitudes for these low-energy inelastic processes. At m π ∼ 806 MeV , using only lattice QCD inputs, a cross section σ 806 MeV ∼ 17 mb is found at an incident neutron speed of v = 2 , 200 m / s . Extrapolating the short-distance contribution to the physical pion mass and combining the result with phenomenological scattering information and one-body couplings, a cross section of σ lqcd ( n p → d γ ) = 334.9 ( + 5.2 − 5.4 ) mb is obtained at the same incident neutron speed, consistent with the experimental value of σ expt ( n p → d γ ) = 334.2 ( 0.5 ) mb .Wed, 08 May 2019 15:20:06 GMThttp://hdl.handle.net/2445/1328622019-05-08T15:20:06Z