122058792
TC2 dynamics and top quark production at NLC
Abstract. We calculate the correction of the TC2 dynamics to the production cross section of the process $e^+e^- \rightarrow t\overline{t}$ in the top color-assisted multiscale technicolor model. Our results show that the corrections mainly come from the effects of the top color gauge boson $Z^{\prime}$ in the s-channel. The total corrections to cross sections $\sigma_L$ and $\sigma_R$ are very large; this can be detected at NLC. The total corrections to the polarized parameters $P_{\mathrm{L}}^t$ and $P_{\mathrm{R}}^t$ may be observed at NLC in most of the parameter space.
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.
122709614
CHARGED TOP-PION CORRECTIONS TO THE TOP QUARK PRODUCTION AT LC IN TC2 THEORY
We discuss the contributions of PGBs (technipions, top-pions) to the top quark production at the high energy e+e- linear collider (LC) experiments in TC2 theory. We find that the corrections to the production cross-section mainly come from top-pions. The corrections of the charged top-pions are significantly large in most of the parameter space. With reasonable value of the parameters, the correction to can reach about 8% which may be detected at LC experiments.
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.
14205678
Phenomenological analysis of B -> PP decays with QCD factorization
In this paper, we study nonleptonic charmless B decays to two light pseudoscalar mesons within the frame of QCD factorization, including the contributions from the chirally enhanced power corrections and weak annihilation. Predictions for the CP-averaged branching ratios and CP-violating asymmetries are given. Within the reasonable range of the parameters, we find that our predictions for the branching ratios of B-->PP are consistent with the present experimental data. But because of the logarithmic divergences at the end points in the hard spectator scatterings and weak annihilation, there are still large uncertainties in these predictions.
11323590
Charmless two-body B decays: A global analysis with QCD factorization
In this paper, we perform a global analysis of $\stackrel{\ensuremath{\rightarrow}}{B}\mathrm{PP}$ and $\mathrm{PV}$ decays with the QCD factorization approach. It is encouraging to observe that the predictions of QCD factorization are in good agreement with experiment. The best fit $\ensuremath{\gamma}$ is around $79\ifmmode^\circ\else\textdegree\fi{}.$ The penguin-diagram--to--tree-diagram ratio $|{P}_{\ensuremath{\pi}\ensuremath{\pi}}{/T}_{\ensuremath{\pi}\ensuremath{\pi}}|$ of ${\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ decays is preferred to be larger than $0.3.$ We also show the confidence levels for some interesting channels: ${B}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0},$ ${K}^{+}{K}^{\ensuremath{-}},$ and ${B}^{+}\ensuremath{\rightarrow}\ensuremath{\omega}{\ensuremath{\pi}}^{+},\ensuremath{\omega}{K}^{+}.$ For $\stackrel{\ensuremath{\rightarrow}}{B}\ensuremath{\pi}{K}^{*}$ decays, they are expected to have smaller branching ratios with more precise measurements.
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.
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.
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.
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.
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.