117986736
On two- and three-point functions of Landau gauge Yang-Mills theory
We present results for the gluon and ghost propagators and the ghost-gluon vertex obtained from Dyson-Schwinger equations. In the zero temperature case we elaborate on the role of the three-gluon vertex and discuss a model that can capture its qualitative features like its anomalous dimensions and a zero crossing of the dressing function. Our results compare well with lattice data. At non-zero temperature we calculated the ghost propagator which agrees rather well with lattice results already within our simple truncation. These results are used to obtain the temperature dependence of the ghost-gluon vertex. We also explain why the ghost propagator does not react to the phase transition despite its direct coupling to the chromoelectric gluon.
15541387
Lower dimensional Yang-Mills theory as a laboratory to study the infrared regime
Lattice studies of the infrared regime of gauge theories are complicated by the required extensive limits, the performed gauge fixing and the demand for high statistics. Using a general power counting scheme for the infrared limit of Landau gauge SU(N) Yang-Mills theory in arbitrary dimensions we show that the infrared behavior of Greens functions is both qualitatively and quantitatively similar in two, three and four spacetime dimensions. Therefore, lower dimensional lattice simulations can serve as a simplified laboratory to analyze the presently applied approximations and to obtain first results for higher correlation functions.
118375544
On the influence of three-point functions on the propagators of Landau gauge Yang-Mills theory
A bstractWe solve the Dyson-Schwinger equations of the ghost and gluon propagators of Landau gauge Yang-Mills theory together with that of the ghost-gluon vertex. The latter plays a central role in many truncation schemes for functional equations. By including it dynamically we can determine its influence on the propagators. We also suggest a new model for the three-gluon vertex motivated by lattice data which plays a crucial role to obtain stable solutions when the ghost-gluon vertex is included. We find that both vertices have a sizable quantitative impact on the mid-momentum regime and contribute to the reduction of the gap between lattice and Dyson-Schwinger equation results. Furthermore, we establish that the three-gluon vertex dressing turns negative at low momenta as suggested by lattice results in three dimensions.
118463320
Infrared analysis of Dyson-Schwinger equations taking into account the Gribov horizon in Landau gauge
The low momentum behavior of the Landau gauge Gribov-Zwanziger action is investigated using the respective Dyson-Schwinger equations. Because of the mixing of the gluon and the auxiliary fields four scenarios can be distinguished for the infrared behavior. Two of them lead to inconsistencies and can be discarded. Another one corresponds to the case where the auxiliary fields behave exactly like the Faddeev-Popov ghosts and the same scaling relation as in standard Landau gauge, {kappa}{sub A}+2{kappa}{sub c}=0, is valid. Even the parameter {kappa} is found to be the same, 0.595. The mixed propagators, which appear, are suppressed in all loops, and their anomalous infrared exponent can also be determined. A fourth case provides an even stricter scaling relation that includes also the mixed propagators, but possesses the same qualitative feature, i.e. the propagators of the Faddeev-Popov ghost and the auxiliary fields are infrared enhanced and the mixed and the gluon propagators are infrared suppressed. In this case the system of equations to obtain the parameter {kappa} is nonlinear in all variables.
119208185
Going beyond the propagators of Landau gauge Yang-Mills theory
We present results for the propagators and the ghost-gluon vertex of Landau gauge Yang-Mills theory obtained from Dyson-Schwinger equations. Solving these three quantities simultaneously constitutes a new step in truncating these equations. We also introduce a new model for the three-gluon vertex that is motivated by lattice results. It features a zero crossing which is confirmed a posteriori by a Dyson-Schwinger calculation. Within our setup we can reproduce lattice data very well. We establish that also for the ghost-gluon vertex a difference between decoupling and scaling solutions is present. For the scaling solution we discuss the possibility of modifying the infrared exponents via an angle dependence of the ghost-gluon vertex. However, no such dependence is found in our calculations. Finally, we calculate the Schwinger function for the gluon propagator.
119167811
The infrared behavior of Landau gauge Yang–Mills theory in d=2, 3 and 4 dimensions
Abstract We develop a general power counting scheme for the infrared limit of Landau gauge SU ( N ) Yang–Mills theory in arbitrary dimensions. Employing a skeleton expansion, we find that the infrared behavior is qualitatively independent of the spacetime dimension d . In the cases d = 2 , 3 and 4 even the quantitative results for the infrared exponents of the vertices differ only slightly. Therefore, corresponding lattice simulations provide interesting qualitative information for the physical case. We furthermore find that the loop integrals depend only weakly on the numerical values of the IR exponents.
161659804
PERFORMANCE AND BACKGROUND MEASUREMENTS OF THE CDMS II TOWER I DETECTORS AT THE STANFORD UNDERGROUND FACILITY
T. SAAB, P.L. BRINK, L. BAUDIS, B. CABRERA, J.P. CASTLE, ANDC. CHANGDepartment of Physics, Stanford University, Stanford, CA 94350, USAR. J. GAITSKELL AND J.P. THOMSONDepartment of Physics, Brown University, Providence, RI 02912, USAD.S. AKERIB, D. DRISCOLL, S. KAMAT, T.A. PERERA, R.W. SCHNEEAND G. WANGDepartment of Physics, Case Western Reserve University, Cleveland, OH44106, USAM. B. CRISLER, R. DIXON AND D. HOLMGRENFermi National Accelerator Laboratory, Batavia, IL 60510, USAJ.H. EMES, R.R. ROSS, A. SMITH AND G.W. SMITHLawrence Berkeley National Laboratory, Berkeley, CA 94720, USAJ.M. MARTINISNational Institute of Standards and Technology, Boulder, CO 80303, USAT. SHUTTDepartment of Physics, Princeton University, Princeton, NJ 08544, USAB.A. YOUNGDepartment of Physics, Santa Clara University, Santa Clara, CA 95053, USAM.S. ARMEL, V. MANDIC, P. MEUNIER, W. RAU, B. SADOULET ANDD.N. SEITZDepartment of Physics, University of California, Berkeley, Berkeley, CA 94720,
119739868
Limits on WIMP–nucleon interactions from the Cryogenic Dark Matter Search at the Soudan Underground Laboratory
Abstract We present the results of the first two data runs of the Cryogenic Dark Matter Search at Soudan Underground Laboratory. These data exclude substantial new parameter space for both spin-independent and spin-dependent WIMP–nucleon interactions within the standard halo model.
122196168
Analysis of the (p, π+) reaction at a momentum transfer below 600 MeV/c☆
Abstract The nuclear production of positive pions in proton-induced reactions on light nuclei is calculated in a Two-Nucleon-Model including π and ϱ single rescattering terms. As a main feature of this model the strong sensitivity of the predictions on the initial and final state interactions observed in the One-Nucleon-Model is considerably reduced. The results reproduce satisfactorily the characteristic trends in the experimental data.
15407865
Light Curves of Type Ia Supernovae from Near the Time of Explosion
We present a set of 11 Type Ia supernova (SN Ia) light curves with dense, premaximum sampling. These supernovae (SNe), in galaxies behind the Large Magellanic Cloud (LMC), were discovered by the SuperMACHO survey. The SNe span a redshift range of z = 0.11-0.35. Our light curves contain some of the earliest premaximum observations of SNe Ia to date. We also give a functional model that describes the SN Ia light-curve shape (in our VR band). Our function uses the "expanding fireball" model of Goldhaber et al. to describe the rising light curve immediately after explosion but constrains it to smoothly join the remainder of the light curve. We fit this model to a composite observed VR-band light curve of three SNe between redshifts of 0.135 and 0.165. These SNe have not been K-corrected or adjusted to account for reddening. In this redshift range, the observed VR band most closely matches the rest-frame V band. Using the best fit to our functional description of the light curve, we find the time between explosion and observed VR-band maximum to be 17.6 ± 1.3(stat) ± 0.07(sys) rest-frame days for a SN Ia with a VR-band Δm-10 of 0.52 mag. For the redshifts sampled, the observed VR-band time of maximum brightness should be the same as the rest-frame V-band maximum to within 1.1 rest-frame days.
121335171
A study of meson-baryon couplings in the constituent quark model
Within the framework of the constituent quark model we discuss the effects of different types of meson-baryon-baryon vertex operators on the form factors and the coupling strengths of the lowest-lying positive and negative parity non-strange baryons. We compare the quark pair creation model (3P0-model) with the SU(6)-model in which mesons are treated as elementary fields that directly couple to the quarks. The latter model is employed both in the so-called static limit and in a modification motivated by Galilei invariance. It is demonstrated that the inclusion of non-static effects simulates some features of the3P0 vertex. Especially the reaction πN→ππN is found to be very sensitive to the different assumptions on the dynamics of theq¯q pair creation process. More indirect hints for the internal structure of the mesons might be obtained from the predicted asymmetry for the two form factors ofN→Δ+π andΔ→N+π, which occurs in the3P0-model, only.