12588055
Predictive ability of QCD sum rules for excited baryons
The masses of octet baryons are calculated by the method of QCD sum rules. Using generalized interpolating fields, three independent sets of QCD sum rules are derived which allow the extraction of low-lying N* states with spin-parity 1/2+, 1/2- and 3/2- in both the non-strange and strange channels. The predictive ability of the sum rules is examined by a Monte Carlo based analysis procedure in which the three phenomenological parameters (mass, coupling, threshold) are treated as free parameters simultaneously. Realistic uncertainties in these parameters are obtained by simultaneously exploring all uncertainties in the QCD input parameters. Those sum rules with good predictive power are identified and their predictions are compared with experiment where available.
118772195
N* Masses from QCD Sum Rules
We report N* masses in the spin-1/2 and spin-3/2 sectors using the method of QCD Sum Rules. They are based on three independent sets derived from generalized interpolating fields. The predictive ability of each sum rule is examined by a Monte-Carlo based analysis procedure in which all three phenomenological parameters (mass, coupling, threshold) are extracted simultaneously. A parity projection technique is also studied.
118327948
Reducing theoretical uncertainties for exclusive Higgs-boson plus one-jet production at the LHC
We resum a class of large Sudakov logarithms affecting Higgs boson production in the exclusive one-jet bin at the LHC. We extend previous results by calculating the full one-loop soft function for this process, which extends the accuracy of the resummation to include the leading three logarithmic corrections at each order in the QCD coupling constant. We match this result to the next-to-leading order cross section and present a detailed numerical study assuming realistic LHC cuts. Careful attention is paid to the matching procedure, and to the theoretical uncertainties induced by residual scale variation. We find that the matched NLL'+ NLO cross section has significantly smaller uncertainties than the fixed-order result, and can be used to alleviate the theoretical errors hindering current Higgs analyses at the LHC.
119097724
η transitions between charmonia with meson loop contributions
We study the $\ensuremath{\eta}$ transitions between $\ensuremath{\psi}(4040/4160)$ and $J/\ensuremath{\psi}$ by introducing charmed meson loops in an effective Lagrangian approach to enhance the decay amplitudes. The branching fractions $\mathcal{B}[\ensuremath{\psi}(4040)\ensuremath{\rightarrow}J/\ensuremath{\psi}\ensuremath{\eta}]$ and $\mathcal{B}[\ensuremath{\psi}(4160)\ensuremath{\rightarrow}J/\ensuremath{\psi}\ensuremath{\eta}]$ estimated in this paper can remarkably explain the experimental measurements of Belle and BESIII within a reasonable parameter range. The ${\ensuremath{\eta}}^{\ensuremath{'}}$ transition between $\ensuremath{\psi}(4160)$ and $J/\ensuremath{\psi}$ is also investigated, and the branching fraction is under the upper limit of CLEO, which can be tested by future experiments.
119236452
CONSTRAINING SUB-PARSEC BINARY SUPERMASSIVE BLACK HOLES IN QUASARS WITH MULTI-EPOCH SPECTROSCOPY. II. THE POPULATION WITH KINEMATICALLY OFFSET BROAD BALMER EMISSION LINES*
A small fraction of quasars have long been known to show bulk velocity offsets (of a few hundred to thousands of km s–1) in the broad Balmer lines with respect to the systemic redshift of the host galaxy. Models to explain these offsets usually invoke broad-line region gas kinematics/asymmetry around single black holes (BHs), orbital motion of massive (~sub-parsec (sub-pc)) binary black holes (BBHs), or recoil BHs, but single-epoch spectra are unable to distinguish between these scenarios. The line-of-sight (LOS) radial velocity (RV) shifts from long-term spectroscopic monitoring can be used to test the BBH hypothesis. We have selected a sample of 399 quasars with kinematically offset broad Hβ lines from the Sloan Digital Sky Survey (SDSS) Seventh Data Release quasar catalog, and have conducted second-epoch optical spectroscopy for 50 of them. Combined with the existing SDSS spectra, the new observations enable us to constrain the LOS RV shifts of broad Hβ lines with a rest-frame baseline of a few years to nearly a decade. While previous work focused on objects with extreme velocity offset (>103 km s–1), we explore the parameter space with smaller (a few hundred km s–1) yet significant offsets (99.7% confidence). Using cross-correlation analysis, we detect significant (99% confidence) radial accelerations in the broad Hβ lines in 24 of the 50 objects, of ~10-200 km s–1 yr–1 with a median measurement uncertainty of ~10 km s–1 yr–1, implying a high fraction of variability of the broad-line velocity on multi-year timescales. We suggest that 9 of the 24 detections are sub-pc BBH candidates, which show consistent velocity shifts independently measured from a second broad line (either Hα or Mg II) without significant changes in the broad-line profiles. Combining the results on the general quasar population studied in Paper I, we find a tentative anti-correlation between the velocity offset in the first-epoch spectrum and the average acceleration between two epochs, which could be explained by orbital phase modulation when the time separation between two epochs is a non-negligible fraction of the orbital period of the motion causing the line displacement. We discuss the implications of our results for the identification of sub-pc BBH candidates in offset-line quasars and for the constraints on their frequency and orbital parameters.
119232556
D-wave heavy-light mesons from QCD sum rules
We study the D-wave (c) over bars heavy meson doublets (1(-), 2(-)) and (2(-), 3(-)) using the method of QCD sum rule in the framework of heavy quark effective theory. Choosing the same threshold values.c around 2.7 Gev, we calculate the masses of the 1(-) and 3(-) states. They are m(D*s1) = 2.81 +/- 0.10 GeV and m(D*s3) = 2.85 +/- 0.08 GeV, consistent with the newly observed D*(s1)(2860) and D*(s3)(2860) states by LHCb. The masses of their 2-partners are calculated to be 2.82 +/- 0.10 and 2.81 +/- 0.08 GeV. The mass splittings within the same doublet are calculated to be m(Ds2) - m(Ds1) = 0.016 +/- 0.007 GeV and m(D*s3) - m(D's2) = 0.039 +/- 0.014 GeV.
118571453
Axial-vector f_1(1285)-f_1(1420) mixing and B_s \to J/\psi (f_1(1285), f_1(1420)) decays
Inspired by the very recent LHCb measurements of $B_s \to J/\psi f_1(1285)$ and the good agreement between the perturbative QCD predictions and the data for many $B \to J/\psi V$ decays, we here investigate the $B_s \to J/\psi f_1(1285)$ and $B_s \to J/\psi f_1(1420)$ decays for the first time by employing the perturbative QCD (pQCD) approach, in which the $1^3P_1$ states $f_1(1285)$ and $f_1(1420)$ are believed to be the mixture of flavor singlet $f_1$ and octet $f_8$ or of quark-flavor states $f_{1q}$ and $f_{1s}$. We show that the pQCD predictions for the branching ratio of $B_s \to J/\psi f_1(1285)$ agree well with the data within errors for the mixing angle $\theta_{^3P_1} \approx 20^\circ (\phi_{^3P_1} \approx 15^\circ)$ between $f_1 (f_{1q})$ and $f_8 (f_{1s})$ states. Furthermore, the branching ratio of $B_s \to J/\psi f_1(1420)$ and the large transverse polarization fractions in these two considered channels are also predicted and will be tested by the LHC and the forthcoming Super-B factory experiments. Based on the decay rates of $B_s \to J/\psi f_1(1285)$ and $B_s \to J/\psi f_1(1420)$ decay modes predicted in the pQCD approach, the extracted mixing angle between $f_1(1285)$ and $f_1(1420)$ is basically consistent with currently available experimental measurements and lattice QCD analysis within still large theoretical errors.