119063228
A note on brane/flux annihilation and dS vacua in string theory
We reconsider the dynamics of p anti-D3 branes inside the Klebanov-Strassler geometry, in which M units of R-R 3-form flux and K units of NS-NS 3-form flux are presented in deformed conifold. We find that anti-D3 branes blow up into a spherical D5-brane at weak string coupling via quantum tunnelling. The D5-brane can be either stable or unstable, depending on number of background flux. The nucleation rate of D5-brane is suppressed by \exp{-Mp^2}. The classical mechanically the evolution of unstable D5-brane annihilates one unit of R-R flux and ends with (K-p) D3-branes. This observation is consistent with one by Kachru, Pearson and Verlinde, who shew that anti-D3 branes in KS geometry can blow up into a spherical NS5 brane at strong string coupling, because NS5-brane is lighter that D5-brane at strong string coupling. We also argue that the system can end with a meta-stable dS vacuum by fine tuning of number of background flux.
119481484
Open spin chain and open spinning string
In this Letter, we study the open spinning strings and their SYM duals. A new class of folded open spinning strings is found. At planar one-loop level in SYM, by solving the thermodynamic limit of the Bethe ansatz equations for an integrable open spin chain, we find good agreement with string theory predictions for energies of both circular and folded two-spin solutions. A universal relation between the open and closed spinning strings is verified in the spin chain approach.
16712339
Intersecting branes and adding flavors to the Maldacena-Nunez background
Following a proposal in ref. [3], we study adding flavors into the Maldacena-Nunez background. It is achieved by introducing spacetime filling D9-branes or intersecting D5'-branes into the background with a wrapping D5-brane. Both D9-branes and D5'-branes can be spacetime filling from the 5D bulk point of view. At the probe limit it corresponds to introducing non-chiral fundamental flavors into the dual = 1 SYM. We propose a method to twist the fundamental flavor which has to involve open string charge. It reflects the fact that coupling fundamental matter to SYM in the dual string theory corresponds to adding an open string sector.
118980773
Green Functions of N=1 SYM and Radial/Energy-Scale Relation
We study counter-terms of one- and two-point Green functions of some special operators in ${\cal N}=1$ SYM from their SUGRA duals from the consideration of AdS/CFT or gauge/gravity correspondence. We consider both the Maldacena-Nunez solution and the Klebanov-Strassler-Tseytlin solution that are proposed to be SUGRA duals of ${\cal N}=1$ SYM. We obtain radial/energy-scale relation for each solution by comparing SUGRA calculations with the field theory results. Using these relations we evaluate the $\beta$-function of ${\cal N}=1$ SYM. We find that the leading order term can be accurately obtained for both solutions and the higher order terms exhibit some ambiguities. We discuss the origin of these ambiguities and conclude that more studies are needed to check whether these SUGRA solutions are exactly dual to ${\cal N}=1$ SYM.
119479056
Integrable spin chain and operator mixing in N=1,2 supersymmetric theories
Abstract We study operator mixing, due to planar one-loop corrections, for composite operators in D =4 supersymmetric theories. We present some N =1,2 Yang–Mills and Wess–Zumino models, in which the planar one-loop anomalous dimension matrix in the sector of holomorphic scalars is identified with the Hamiltonian of an integrable quantum spin chain with SU (3) or SU (2) symmetry, even if the theory is away from the conformal points. This points to a more universal origin of the integrable structure beyond superconformal symmetry. We also emphasize the role of the superpotential in the appearance of the integrable structure. The computations of operator mixing in our examples by solving Bethe ansatz equations show some new features absent in N =4 SYM.
8346546
Integrable open spin chain in super Yang-Mills and the plane-wave/SYM duality
We investigate the integrable structures in an = 2 superconformal Sp(N) Yang-Mills theory with matter, which is dual to an open+closed string system. We restrict ourselves to the BMN operators that correspond to free string states. In the closed string sector, an integrable structure is inherited from its parent theory, = 4 SYM. For the open string sector, the planar one-loop mixing matrix for gauge invariant holomorphic scalar operators is identified with the hamiltonian of an integrable SU(3) open spin chain. Using the K-matrix formalism we identify the integrable open-chain boundary conditions that correspond to string boundary conditions. The solutions to the algebraic Bethe ansatz equations (ABAE) with a few impurities are shown to recover the anomalous dimensions that exactly match the spectrum of free open string in the plane-wave background. We also discuss the properties of the solutions of ABAE beyond the BMN regime.
16228307
Jet and Leading Hadron Production in High-energy Heavy-ion Collisions
Jet tomography has become a powerful tool for the study of properties of dense matter in high-energy heavy-ion collisions. I will discuss recent progresses in the phenomenological study of jet quenching, including momentum, colliding energy and nuclear size dependence of single hadron suppression, modification of dihadron correlations and the soft hadron distribution associated with a quenched jet.
110752379
The High Dynamics Readout of PMT for BGO Calorimeter
For one cell of BGO-EM energy deposition of electron/gamma with energy above TeV is between 0.5 MIPs and 105 MIPs, the readout system need to cover this high dynamic range.
55951342
STUDY ON FREQUENCY CHANGE BY 3D RECONSTRUCTION OF DEFORMED CAVITIES OF LINAC COLLINEAR LOAD*
Collinear load, consisted of several coaxial cavities, is a substitute for traditional waveguide-type load to absorb the remnant power of the LINAC and makes the accelerating structure compact and small-size. The power loss on the cavities of collinear load brings thermal deformation which affects their resonant frequency deeply. In this paper, a new approach of 3D reconstruction of the thermal deformed cavities is utilized to evaluate the accurate influence on frequency change caused by non-uniform deformation and water cooling strategies of collinear absorbing load are studied. Then the thermal behavior of a six-cavity collinear load, which is coated with Kanthal alloy and FeSiAl alloy and used on a 2856MHz, 2π/3 mode respectively, is researched. The results show that the collinear load with Kanthal alloy can only absorb up to 10kW, while with FeSiAl alloy it can dissipate 15kW when the water flow controlled within 3.0kg/s for energy saving.
118402964
Higgs boson decays and production in the left–right twin Higgs model
The left-right twin Higgs model predicts one neutral Higgs boson �0 and it acquires mass m�0 � µr with the µ term, which can be lighter than half the SM-like Higgs boson mass in a portion of parameter space. Thus, the SM-like Higgs boson h can dominantly decay into a pair of light neutral Higgs bosons especially when mh is below the WW threshold. First, we examine the branching ratios of the SM-like Higgs boson decays and find that the new decay mode h ! �0�0 is dominant for the case of mh > 2m�0 . Then we study the production via gluon fusion followed by the decay into two photons or two weak gauge bosons and found that the production rate can be significantly suppressed for some
117281673
Energy dependence of jet transport parameter and parton saturation in quark-gluon plasma
We study the evolution and saturation of the gluon distribution function in the quark-gluon plasma as probed by a propagating parton and its effect on the computation of jet quenching or transport parameter $\hat q $. For thermal partons, the saturation scale $Q2_s$ is found to be proportional to the Debye screening mass $\mu_D2$. For hard probes, evolution at small $x=Q2_s/6ET$ leads to jet energy dependence of hat q. We study this dependence for both a conformal gauge theory in weak and strong coupling limit and for (pure gluon) QCD. The energy dependence can be used to extract the shear viscosity $\eta$ of the medium since $\eta$ can be related to the transport parameter for thermal partons in a transport description. We also derive upper bounds on the transport parameter for both energetic and thermal partons. The later leads to a lower bound on shear viscosity-to-entropy density ratio which is consistent with the conjectured lower bound $\eta/s\geq 1/4\pi$. Implications on the study of jet quenching at RHIC and LHC and the bulk properties of the dense matter are discussed.