Search results for "complex analysis"
showing 10 items of 245 documents
Lower than low: Perspectives on zero- to ultralow-field nuclear magnetic resonance
2021
Abstract The less-traveled low road in nuclear magnetic resonance is discussed, honoring the contributions of Prof. Bernhard Blumich, aspiring towards reaching ‘a new low.’ A history of the subject and its current status are briefly reviewed, followed by an effort to prophesy possible directions for future developments.
The index theorem on the lattice with improved fermion actions
1998
We consider a Wilson-Dirac operator with improved chiral properties. We show that, for arbitrarily rough gauge fields, it satisfies the index theorem if we identify the zero modes with the small real eigenvalues of the fermion operator and use the geometrical definition of topological charge. This is also confirmed in a numerical study of the quenched Schwinger model. These results suggest that integer definitions of the topological charge based on counting real modes of the Wilson operator are equivalent to the geometrical definition. The problem of exceptional configurations and the sign problem in simulations with an odd number of dynamical Wilson fermions are briefly discussed. We consi…
Non-zero chemical potential and the shape of the pT-distribution of hadrons in heavy-ion collisions
1990
Abstract The pT-spectra of negative particles from 200 GeV/nucleon O + Au and S + S collisions, measured at CERN by the NA35 collaboration, are fitted by a thermal distribution of massive pions which are strongly out of chemcial equilibrium. Both sets of data are consistent with the same values of temperature and chemical potential, T ≈ 165 MeV and μ ≈ 120 MeV. The low pT behaviour of the measured spectra seems to indicate that the transverse flow in these collisions is not strong.
Analytic results for planar three-loop integrals for massive form factors
2016
We use the method of differential equations to analytically evaluate all planar three-loop Feynman integrals relevant for form factor calculations involving massive particles. Our results for ninety master integrals at general $q^2$ are expressed in terms of multiple polylogarithms, and results for fiftyone master integrals at the threshold $q^2=4m^2$ are expressed in terms of multiple polylogarithms of argument one, with indices equal to zero or to a sixth root of unity.
The reactor mixing angle and CP violation with two texture zeros in the light of T2K
2012
We reconsider the phenomenological implications of two texture zeros in symmetric neutrino mass matrices in the light of the recent T2K result for the reactor angle and the new global analysis which gives also best fit values for the Dirac CP phase delta. The most important results of the analysis are: Among the viable cases classified by Frampton et al. only A1 and A2 predict the reactor mixing angle to be different from zero at 3 sigma. Furthermore these two cases are compatible only with a normal mass spectrum in the allowed region for the reactor angle. At the best fit value A1 and A2 predict 0.024 >= sin^2(theta13) >= 0.012 and 0.014 <= sin^2(theta13) <= 0.032, respectively…
ϒ production in p–Pb collisions at sNN=8.16 TeV
2020
$\Upsilon$ production in p-Pb interactions is studied at the centre-of-mass energy per nucleon-nucleon collision $\sqrt{s_{\rm{NN}}}$ = 8.16 TeV with the ALICE detector at the CERN LHC. The measurement is performed reconstructing bottomonium resonances via their dimuon decay channel, in the centre-of-mass rapidity intervals $2.03 < y_{\rm{cms}} < 3.53$ and $-4.46 < y_{\rm{cms}} < -2.96$, down to zero transverse momentum. In this work, results on the inclusive $\Upsilon(1\rm{S})$ production cross section as a function of rapidity and transverse momentum are presented. The corresponding nuclear modification factor shows a suppression of the $\Upsilon(1\rm{S})$ yields with respect to pp collis…
A modified born term model for π± Δ electroproduction
1974
An electric Born type model is used to describeπ±Δ electroproduction at high energies. The electric pion form factor is taken from VDM; the contact term form factor and theΔ form factor are set equal to the proton form factor (or equal to zero) which is left as an arbitrary parameter, and is determined by a fit of the model to the recentπ+δ0 andπ−Δ++ electroproduction data.
Chiral dynamics in theγp→π0ηpandγp→π0K0Σ+reactions
2006
Using a chiral unitary approach for meson-baryon scattering in the strangeness zero sector, where the ${N}^{*}(1535){S}_{11}$ resonance is dynamically generated, we study the reactions $\ensuremath{\gamma}p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}\ensuremath{\eta}p$ and $\ensuremath{\gamma}p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{K}^{0}{\ensuremath{\Sigma}}^{+}$ at photon energies at which the final states are produced close to threshold. Among several reaction mechanisms, we find the most important is the excitation of the ${\ensuremath{\Delta}}^{*}(1700){D}_{33}$ state, which subsequently decays into a pseudoscalar meson and a baryon belonging to the $\ensuremath{\Delta}(1232)…
Spin asymmetry A1d and the spin-dependent structure function g1d of the deuteron at low values of x and Q2
2007
Abstract We present a precise measurement of the deuteron longitudinal spin asymmetry A 1 d and of the deuteron spin-dependent structure function g 1 d at Q 2 1 ( GeV / c ) 2 and 4 × 10 −5 x 2.5 × 10 −2 based on the data collected by the COMPASS experiment at CERN during the years 2002 and 2003. The statistical precision is tenfold better than that of the previous measurement in this region. The measured A 1 d and g 1 d are found to be consistent with zero in the whole range of x.
Mass ofAl23for testing the isobaric multiplet mass equation
2009
The mass excess of the proton-rich nucleus $^{23}\mathrm{Al}$ has been measured with the JYFLTRAP Penning trap setup. As a result of our experiment we obtain a mass excess of 6748.07(34) keV, and by combining the value to existing experimental data we have tested the validity of the isobaric multiplet mass equation $(\mathrm{IMME})$ for the $T=3/2$ quartet in the $A=23$ isobar. The fit to the IMME results in a vanishing cubic term equivalent to zero with high precision [$0.22(42)$ keV].