118393254
Study $X_{c}(3250)$ as a $D_{0}^{*}(2400)N$ molecular state
We present a QCD sum rule analysis for the newly observed resonance $X_{c}(3250)$ by assuming it as a $D_{0}^{*}(2400)N$ molecular state. Technically, contributions of operators up to dimension 12 are included in the operator product expansion (OPE). We find that it is difficult to find the conventional OPE convergence in this work. By trying releasing the rigid OPE convergence criterion, one could find that the OPE convergence is still under control in the present work and the numerical result for $D_{0}^{*}(2400)N$ state is $3.18\pm0.51 {GeV}$, which is in agreement with the experimental data of $X_{c}(3250)$. In view of that the conventional OPE convergence is not obtained here, thus only weak conclusions can be drawn regarding the explanation of $X_{c}(3250)$ in terms of a $D_{0}^{*}(2400)N$ molecular state. As a byproduct, the mass for the bottom counterpart $\bar{B}_{0}^{*}N$ state is predicted to be $6.50\pm0.49 {GeV}$.
118448190
Improved QCD sum rule study of $Z_{c}(3900)$ as a $\bar{D}D^{*}$ molecular state
In the framework of QCD sum rules, we present an improved study of our previous work [Phys. Rev. D 80, 056004 (2009)], particularly on the $\overline{D}{D}^{*}$ molecular state, to investigate the possibility that the newly observed ${Z}_{c}(3900)$ is a $S$-wave $\overline{D}{D}^{*}$ molecular state. To ensure the quality of QCD sum rule analysis, contributions of up to dimension nine are calculated to test the convergence of operator product expansion (OPE). We find that the two-quark condensate $⟨\overline{q}q⟩$ is very large and makes the standard OPE convergence (i.e. the perturbative at least larger than each condensate contribution) happen at very large values of Borel parameters. By releasing the rigid OPE convergence criterion, one could find that the OPE convergence is still under control. We arrive at the numerical result $3.86\ifmmode\pm\else\textpm\fi{}0.27\text{ }\text{ }\mathrm{GeV}$ for $\overline{D}{D}^{*}$, which agrees with the mass of ${Z}_{c}(3900)$ and could support the explanation of ${Z}_{c}(3900)$ in terms of a $S$-wave $\overline{D}{D}^{*}$ molecular state.
117848077
Could $Z_{b}(10610)$ be a $B^{*}\bar{B}$ molecular state?
Assuming the newly observed structure $Z_{b}(10610)$ as a bottomonium-like molecular state $B^{*}\bar{B}$, we calculate its mass in the framework of QCD sum rules. The numerical result is $10.54\pm0.22 GeV$ for $B^{*}\bar{B}$, which coincide with the mass of $Z_{b}(10610)$. This consolidates the statement made by Belle Collaboration that the $Z_{b}(10610)$ resonance could be a $B^{*}\bar{B}$ molecular state.
119297689
Doubly heavy baryons in QCD sum rules
The mass spectra of doubly heavy baryons are systematically calculated in the framework of QCD sum rules. With a tentative heavy-diquark-light-quark configuration, the interpolating currents representing the doubly heavy baryons are proposed. Contributions of the operators up to dimension six are included in operator product expansion. The numerical results are compatible with other theoretical predictions, which may support the (QQ)-(q) structure of doubly heavy baryons.
118586798
Heavy baryon spectroscopy in QCD
We perform a systematic study of the masses of charmed and bottom baryons in the framework of the QCD sum rule approach. Contributions of the operators up to dimension six are included in operator product expansion. The resulting heavy baryon masses from the calculations are well consistent with the experimental values, and predictions to the spectroscopy of the unobserved bottom baryons are also presented.
119234067
The $P$-wave $[cs][\bar{c}\bar{s}]$ tetraquark state: $Y(4260)$ or $Y(4660)$?
The mass of $P$-wave $cs$-scalar-diquark $\bar{c}\bar{s}$-scalar-antidiquark state is computed in the framework of QCD sum rules. The result $4.69\pm0.36{GeV}$ is in good agreement with the experimental value of Y(4660) but higher than Y(4260)'s, which supports the $P$-wave $[cs][\bar{c}\bar{s}]$ configuration for Y(4660) while disfavors the interpretation of Y(4260) as the $P$-wave $[cs][\bar{c}\bar{s}]$ state. In the same picture, the mass of $P$-wave $[bs][\bar{b}\bar{s}]$ is predicted to be $11.19\pm0.49 {GeV}$.
119297105
On the two-loop hexagon Wilson loop remainder function in N=4 SYM
Abstract A duality relation has been proposed between the planar gluon MHV amplitudes and light-like Wilson loops in N = 4 super Yang–Mills. At six-point two-loop, the results for the planar gluon MHV amplitude and for the light-like Wilson loop agree, but they both differ from the Bern–Dixon–Smirnov ansatz by a finite remainder function. Recently Del Duca, Duhr and Smirnov presented an analytical result for the two-loop hexagon Wilson loop remainder function in general kinematics. Their result is rather lengthy, and the dependence on the conformal cross ratios appears in a complicated way. Here we present an alternate, more compact representation for the two-loop hexagon Wilson loop remainder function.
119433952
Scaling behavior of the overlap quark propagator in the Landau gauge
The properties of the momentum space quark propagator in Landau gauge are examined for the overlap quark action in quenched lattice QCD. Numerical calculations are done on three lattices with different lattice spacings and similar physical volumes to explore the approach of the quark propagator toward the continuum limit. We have calculated the nonperturbative momentum-dependent wave-function renormalization function $Z({\ensuremath{\zeta}}^{2};p)$ and the nonperturbative mass function $M(p)$ for a variety of bare quark masses and perform an extrapolation to the chiral limit. We find the behavior of $Z({\ensuremath{\zeta}}^{2};p)$ and $M(p)$ are in reasonable agreement between the two finer lattices in the chiral limit, however the data suggest that an even finer lattice is desirable. The large momentum behavior is examined to determine the quark condensate.
119115860
Justifying the naive partonic sum rule for proton spin
Abstract We provide a theoretical basis for understanding the spin structure of the proton in terms of the spin and orbital angular momenta of free quarks and gluons in Feynman's parton picture. We show that each term in the Jaffe–Manohar spin sum rule can be related to the matrix element of a gauge-invariant, but frame-dependent operator through a matching formula in large-momentum effective field theory. We present all the matching conditions for the spin content at one-loop order in perturbation theory, which provide a basis to calculate parton orbital angular momentum in lattice QCD at leading logarithmic accuracy.
118385893
On short interval expansion of Rényi entropy
A bstractRényi entanglement entropy provides a new window to study the AdS/CFT correspondence. In this paper we consider the short interval expansion of Rényi entanglement entropy in two-dimensional conformal field theory. This amounts to do the operator product expansion of the twist operators. We focus on the vacuum Verma module and consider the quasiprimary operators constructed from the stress tensors. After obtaining the expansion coefficients of the twist operators to level 6 in vacuum Verma module, we compute the leading contributions to the Rényi entropy, to order 6 in the short interval expansion. In the case of one short interval on cylinder, we reproduce the first several leading contributions to the Rényi entropy. In the case of two short disjoint intervals with a small cross ratio x, we obtain not only the classical and 1-loop quantum contributions to the Rényi entropy to order x6, both of which are in perfect match with the ones found in gravity, but also the leading 1/c contributions, which corresponds to 2-loop corrections in the bulk.
54928710
Gravity/Fluid Correspondence and Its Application on Bulk Gravity with Gauge Field
As the long wavelength limit of the AdS/CFT correspondence, the gravity/fluid correspondence has been shown to be a useful tool for extracting properties of the fluid on the boundary dual to the gravity in the bulk. In this paper, after briefly reviewing the algorithm of gravity/fluid correspondence, we discuss the results of its application on bulk gravity with a gauge field. In the presence of a gauge field, the dual fluid possesses more interesting properties such as its charge current. Furthermore, an external field could affect the charge current, and the Chern-Simons term also induces extra structures to the dual current giving anomalous transport coefficients.