Conformal defects in supergravity — backreacted Dirac delta sources

We construct numerically gravitational duals of theories deformed by localized Dirac delta sources for scalar operators both at zero and at finite temperature. We find that requiring that the backreacted geometry preserves the original scale invariance of the source uniquely determines the potential for the scalar field to be the one found in a certain Kaluza-Klein compactification of 11 D supergravity. This result is obtained using an efficient perturbative expansion of the backreacted background at zero temperature and is confirmed by a direct numerical computation. Numerical solutions at finite temperatures are obtained and a detailed discussion of the numerical approach to the treatment of the Dirac delta sources is presented. The physics of defect configurations is illustrated with a calculation of entanglement entropy

Twist Decomposition of Proton Structure from BFKL and BK Amplitudes

An analysis of twist composition of Balitsky--Kovchegov (BK) amplitude is performed in the double logarithmic limit. In this limit, the BK evolution of color dipole--proton scattering is equivalent to BFKL evolution which follows from vanishing of the Bartels vertex in the collinear limit. We perform twist decomposition of the BFKL/BK amplitude for proton structure functions and find compact analytic expressions that provide accurate approximations for higher twist amplitudes. The BFKL/BK higher twist amplitudes are much smaller than those following from eikonal saturation models

Wilson Loops with Arbitrary Charges

We discuss how to implement, in lattice gauge theories, external charges which are not commensurate with an elementary gauge coupling. It is shown that an arbitrary, real power of a standard Wilson loop (or Polyakov line) can be defined and consistently computed in lattice formulation of Abelian, two dimensional gauge theories. However, such an observable can excite quantum states with integer fluxes only. Since the non-integer fluxes are not in the spectrum of the theory, they cannot be created, no matter which observable is chosen. Also the continuum limit of above averages does not exist unless the powers in question are, in fact, integer. On the other hand, a new continuum limit exists, which is rather intuitive, and where above observables make perfect sense and lead to the string tension proportional to the square of arbitrary (non-necessary commensurate with gauge coupling) charge

Determination of the COSY Proton Beam Polarization Using the WASA Detector

The dynamics of $\eta$-meson production and the interaction of $\eta$ mesons with nucleons can be studied using the $\vec{p}p\to pp\eta$ reaction via measurements of the analyzing power $A_{y}$. To this end, we have performed a measurement of the $\vec{p}p\to pp\eta$ reaction using the WASA-at-COSY detector, which provides large acceptance and is $\varphi$-symmetric. The experiment was carried out for the beam momenta of $2026$~MeV/$c$ and $2188$~MeV/$c$. In this article, we present a method and results for the determination of the degree of the beam polarization

Improved KSK_{\rm S} Tagging Procedure and Its Impact on Physics at KLOE-2

The KLOE experiment at the DA$\Phi$NE $\phi$-factory performed precise studies of charged and neutral kaon physics, low energy QCD, as well as tests of CP and CPT invariance. For the new run, the KLOE has been upgraded by adding new tagger systems for the $\gamma\gamma$ physics, the inner tracking chamber and two calorimeters in the final focusing region. We are also improving on kaon identification techniques, in particular algorithms for the $K_{\rm S}$ meson tagging. In this article, we discuss the impact of the improved tagging procedure on studies of the $K_{\rm S}$ decays

Bose--Einstein Correlations and Thermal Cluster Formation in High-energy Collisions

The blast wave model is generalized to include the production of thermal clusters, as suggested by the success of the statistical model of particle production at high energies. The formulae for the HBT correlation functions and the corresponding HBT radii are derived

Unveiling the significance of eigenvectors in diffusing non-Hermitian matrices by identifying the underlying Burgers dynamics

Following our recent letter [1] , we study in detail an entry-wise diffusion of non-hermitian complex matrices. We obtain an exact partial differential equation (valid for any matrix size N and arbitrary initial conditions) for evolution of the averaged extended characteristic polynomial. The logarithm of this polynomial has an interpretation of a potential which generates a Burgers dynamics in quaternionic space. The dynamics of the ensemble in the large N limit is completely determined by the coevolution of the spectral density and a certain eigenvector correlation function. This coevolution is best visible in an electrostatic potential of a quaternionic argument built of two complex variables, the first of which governs standard spectral properties while the second unravels the hidden dynamics of eigenvector correlation function. We obtain general formulas for the spectral density and the eigenvector correlation function for large N and for any initial conditions. We exemplify our studies by solving three examples, and we verify the analytic form of our solutions with numerical simulations

A c=1 phase transition in two-dimensional CDT/Horava–Lifshitz gravity?

We study matter with central charge c>1 coupled to two-dimensional (2d) quantum gravity, here represented as causal dynamical triangulations (CDT). The 2d CDT is known to provide a regularization of (Euclidean) 2d Hořava–Lifshitz quantum gravity. The matter fields are massive Gaussian fields, where the mass is used to monitor the central charge c . Decreasing the mass we observe a higher order phase transition between an effective c=0 theory and a theory where c>1 . In this sense the situation is somewhat similar to that observed for “standard” dynamical triangulations (DT) which provide a regularization of 2d quantum Liouville gravity. However, the geometric phase observed for c>1 in CDT is very different from the corresponding phase observed for DT

Heavy quark diffusion in strongly coupled anisotropic plasmas

We study the Langevin diffusion of a relativistic heavy quark in anisotropic strongly coupled theories in the local limit. Firstly, we use the axion space-dependent deformed anisotropic $\mathcal{N}$ = 4 sYM, where the geometry anisotropy is always prolate, while the pressure anisotropy may be prolate or oblate. For motion along the anisotropic direction we find that the effective temperature for the quark can be larger than the heat bath temperature, in contrast to what happens in the isotropic theory. The longitudinal and transverse Langevin diffusion coefficients depend strongly on the anisotropy, the direction of motion and the transverse direction considered. We analyze the anisotropy effects to the coefficients and compare them to each other and to them of the isotropic theory. To examine the dependence of the coefficients on the type of the geometry, we consider another bottom-up anisotropic model. Changing the geometry from prolate to oblate, certain diffusion coefficients interchange their behaviors. In both anisotropic backgrounds we find cases that the transverse diffusion coefficient is larger than the longitudinal, but we find no negative excess noise

TauSpinner: a tool for simulating CP effects in H→ττ decays at LHC

In this paper, we discuss application of the TauSpinner package as a simulation tool for measuring the CP state of the newly discovered Higgs boson using the transverse spin correlations in the H→ττ decay channel. We discuss application for its main background Z/γ∗→ττ as well. The TauSpinner package allows to add, with the help of weights, transverse spin correlations corresponding to any mixture of scalar/pseudoscalar state, on already existing events using information from the kinematics of outgoing τ leptons and their decay products only. This procedure can be used when polarimetric vectors of the τ s decays and density matrix for τ -pair production are not stored with the event sample. We concentrate on the well-defined effects for the Higgs (or Higgs-like scalar) decays, which are physically separated from the production processes. TauSpinner also allows to reintroduce (or remove) spin correlations to events from Drell–Yan Z/γ∗→ττ process, the main background for the Higgs parity observables, again with the help of weights only. From the literature, we recall well-established observables, developed for measuring the CP of the Higgs, and use them as benchmarks for illustrating applications of the TauSpinner package. We also include a description of the code and prepared testing examples