119250193
Spontaneous Pair Production in Reissner-Nordstrom Black Holes
We investigate the spontaneous pair production---including the Schwinger mechanism and the Hawking thermal radiation---of charged scalar particles from the near-horizon region of a (near) extremal Reissner-Nordstr\"om black hole. The paradigm is equivalent to the dynamics of the charged scalar field in a specific ${\mathrm{AdS}}_{2}\ifmmode\times\else\texttimes\fi{}{S}^{2}$ spacetime with a constant electric field. Two possible boundary conditions are adopted to explicitly compute the corresponding production rate and absorption cross section. It is shown that the Schwinger production rate can be eventually suppressed by the increasing attractive gravitational force as the geometry changes from the extremal to the near extremal black hole. Consequently, the Schwinger mechanism and the Hawking radiation are generically indistinguishable for the near-extremal black holes. The holographic description dual to the pair production is also briefly discussed.
55380857
Mimic the optical conductivity in disordered solids via gauge/gravity duality ✩
Abstract We study the optical conductivity in a ( 2 + 1 ) -dimensional non-relativistic field theory holographically dual to a ( 3 + 1 ) -dimensional charged Lifshitz black brane within the Einstein–Maxwell-dilaton theory. Surprisingly, we find that the optical AC conductivity satisfies the nontrivial (non-)power law scaling in the high frequency regime rather than approaching to a constant when the dynamical critical exponent z > 1 , which is qualitatively similar to those in various disordered solids in condensed matter systems. Besides, this (non-)power law scaling behavior shows some universality, which is robust against the temperatures. We argue that the peculiar scaling behavior of AC conductivity may stem from the couplings of the dilaton field with the gauge fields and also the logarithmic behavior near the boundary in the Lifshitz spacetime.
118483841
The RN/CFT correspondence revisited
We reconsidered the quantum gravity description of the near horizon extremal Reissner-Nordstrøm black hole in the viewpoint of the AdS2/CFT1 correspondence. We found that, for pure electric case, the right moving central charge of dual 1D CFT is 6Q2 which is different from the previous result 6Q3 of left moving sector obtained by warped AdS3/CFT2 description. We discussed the discrepancy in these two approaches and examined novel properties of our result.
119212173
Note on Chern-Simons term correction to holographic entanglement entropy
From the perspective of AdS/CFT correspondence, we study the gravitational Chern-Simons term correction to the holographic entanglement entropy of CFT on the conformal boundary of asymptotically AdS3 spacetime using the off-shell Euclidean path integral method. We show that, like the BTZ black hole entropy, the holographic entanglement entropy is indeed modified due to the gravitational Chern-Simons term although the bulk geometry does not change.
118500432
Twofold Hidden Conformal Symmetries of the Kerr-Newman Black Hole
In this paper, we suggest that there are two different individual 2D CFTs holographically dual to the Kerr-Newman black hole, coming from the corresponding two possible limits — the Kerr/CFT and Reissner-Nordstrcorrespondences, namely there exist the Kerr-Newman/CFTs du- alities. A probe scalar field at low frequencies turns out can exhibit two different 2D conformal symmetries (named by J- and Q-pictures, respectively) in its equation of motion when the asso- ciated parameters are suitably specified. These twofold dualities are supported by the matchings of entropies, absorption cross sections and real time correlators computed from both the gravity and the CFT sides. Our results lead to a fascinating "microscopic no hair conjecture" — for each macroscopic hair parameter, in additional to the mass of a black hole in the Einstein-Maxwell theory, there should exist an associated holographic CFT2 description.
118555844
Holographic dual of the dyonic Reissner-Nordström black hole
It is shown that the hidden conformal symmetry, namely SO(2,2) ∼ SL(2,R)L × SL(2,R)R symmetry, of the non-extremal dyonic Reissner-Nordstrblack hole can be probed by a charged massless scalar field at low frequencies. The existence of such hidden conformal symmetry suggests that the field theory holographically dual to the 4D Reissner-Nordstrom black hole indeed should be a 2D CFT. Although the associated AdS3 structure does not explicitly appear in the near horizon geometry, the primary parameters of the dual CFT2 can be exactly obtained without the necessity of embedding the 4D Reissner-Nordstrblack hole into 5D spacetime. The duality is further supported by comparing the absorption cross sections and real-time correlators obtained from both the CFT and the gravity sides.
119214722
Study on the properties of the coupling constants of $J/\psi \rightarrow VP$ decays
Basing on the branching fractions of J/\psi \to VP from different experiments, we investigate on the properties of the coupling constants of J/\psi \to VP decays with a model-dependent approach. We find that the octet coupling constant, g_8, of strong interaction is about twice larger than that of the singlet coupling constant g_1; the electromagnetic breaking parameters g^i_E are larger than the mass breaking parameters g^i_M, moreover, the three parameters of electromagnetic effect are about equal, but the three parameters of mass effect are obviously different and their uncertainties are also large; and the phase angle between strong and electromagnetic interaction is in the range of 70^{\circ} \sim 80^{\circ}. It deepens our understanding of the coupling constant of J/\psi \to VP decays.
118825098
Spectator scattering and annihilation contributions as a solution to the $\pi K$ and $\pi \pi$ puzzles within QCD factorization approach
The large branching ratios for pure annihilation $\bar{B}_s^0$ $\to$ $\pi^+ \pi^-$ and $\bar{B}_d^0$ $\to$ $K^+ K^-$ decays reported by CDF and LHCb collaborations recently and the so-called ${\pi}K$ and ${\pi}{\pi}$ puzzles indicate that spectator scattering and annihilation contributions are important to the penguin-dominated, color-suppressed tree dominated, and pure annihilation nonleptonic $B$ decays. Combining the available experimental data for $B_{u,d}$ ${\to}$ $\pi \pi$, ${\pi}K$ and $K \bar{K}$ decays, we do a global fit on the spectator scattering and annihilation parameters $X_H({\rho}_H$, ${\phi}_H)$, $X_A^i({\rho}_A^{i},{\phi}_A^{i})$ and $X_A^f({\rho}_A^{f},{\phi}_A^{f})$, which are used to parameterize the endpoint singularity in amplitudes of spectator scattering, nonfactorizable and factorizable annihilation topologies within the QCD factorization framework, in three scenarios for different purpose. Numerically, in scenario II, we get $({\rho}_A^{i},{\phi}_A^{i}[^{\circ}])=(2.88^{+1.52}_{-1.30},-103^{+33}_{-40})$ and $({\rho}_A^{f},{\phi}_A^{f}[^{\circ}])=(1.21^{+0.22}_{-0.25},-40^{+12}_{-8})$ at the $68\%$ confidence level, which are mainly demanded by resolving ${\pi}K$ puzzle and confirm the presupposition that $X_A^i\neq X_A^f$. In addition, correspondingly, the $B$-meson wave function parameter $\lambda_B$ is also fitted to be $0.18^{+0.11}_{-0.08}\, MeV$, which plays an important role for resolving both ${\pi}K$ and $\pi\pi$ puzzles. With the fitted parameters, the QCDF results for observables of $B_{u,d}$ $\to$ $\pi \pi$, $\pi K$ and $K \bar{K}$ decays are in good agreement with experimental measurements. Much more experimental and theoretical efforts are expected to understand the underlying QCD dynamics of spectator scattering and annihilation contributions.
118594300
Phenomenological study of the $B_{c}$ ${\to}$ $BP$, $BV$ decays with perturbative QCD approach
Inspired by the recent LHCb measurements and forthcoming great potential on $B_{c}$ meson, we study the exclusive $B_{c}$ ${\to}$ $B_{q}P$, $B_{q}V$ decays with the perturbative QCD approach, where $q$ $=$ $u$, $d$, $s$; $P$ and $V$ denote the lightest pseudoscalar and vector $SU(3)$ nonet meson, respectively. By retaining the quark transverse momentum, employing the Sudakov factors, and choosing the typical scale as the maximum virtualities of the internal particles, we calculate the $B_{c}$ ${\to}$ $B$ transition from factors, and our results show that about 90\% contribution to form factors come from the ${\alpha}_{s}/{\pi}$ $<$ $0.3$ region. The contributions of penguin and annihilation to branching ratios are very small due to the serious suppression by the CKM factors. There is some hierarchy relations among the $B_{c}$ ${\to}$ $BP$, $BV$ decays. The branching ratios for $B_{c}$ ${\to}$ $B_{d,s}{\pi}$, $B_{d,s}{\rho}$, $B_{s}K$ are large and could be measured by the running LHCb.
123690941
Pseudo-Goldstone boson corrections to top-quark production at the Fermilab Tevatron in a topcolour-assisted multiscale technicolour model
Using a topcolour-assisted multiscale technicolour model, we calculate the corrections of pseudo-Goldstone bosons (technipions, top pions) to the cross section of the process q→t at the Fermilab Tevatron. Our results show that corrections mainly come from top pions. With reasonable values of the parameters, the correction can increase the total t production cross section σt by as much as 17%. This may provide a window to detect top pions.
55522246
COURANT-SNYDER INVARIANT DENSITY SCREENING METHOD FOR EMITTANCE ANALYSIS *
The emittance is an important characteristic of describing charged particle beams. In hadron accelerators, we often meet irregular beam distributions that are not appropriate to be described with a single rms emittance or 95% emittance or total emittance. In this paper, it is pointed out that in many cases beam halo should be described with very different Courant-Snyder parameters from the ones for beam core. A new method – CourantSnyder invariant density screening method is introduced for analyzing emittance data clearly and accurately.