15332649
String fluctuations, AdS/CFT and the soft pomeron intercept
Abstract We study high energy scattering amplitudes in a strongly coupled (confining) gauge theory using the AdS/CFT correspondence. The scattering described by a Wilson line/loop correlation function was shown earlier to correspond to minimal surfaces of the helicoid type, and gave amplitudes with unit intercept and linear trajectory. In this Letter we find the correction to the intercept from quadratic fluctuations of the string worldsheet around the helicoid. The relevant term comes from analytical continuation of a Luscher like term. It is coupling-constant independent and proportional to the number of effective transverse flat dimensions. The shift of the intercept, under our assumptions, is n ⊥ /96, and for n ⊥ =7,8 gives, respectively, 0.0729, 0.083. Incidentally we note that this is surprisingly close to the observed value of 0.08.
11654094
The decay of quantum D-branes
Abstract We study the quantum decay of D0-branes in two-dimensional 0B string theory. The quantum nature of the branes provides a natural cut-off for the closed string emission rate. We find exact quantum mechanical wave functions for the decaying branes and show how one can include the effects of the Fermi sea for any string coupling (Fermi energy).
123645613
Chiral Disorder and the QCD Dirac Spectrum
Using the Cell-Mann-Oakes-Renner (COR) relation together with semi-classical argu­ ments, we show that the bulk quark spectrum in QCD exhibits a variety of regimes includ­ ing the ergodic one described by random matrix theory. We suggest that a class of chiral transitions in QCD is of the metal-insulator type, universal spectral statistics at the critical point.
7393750
Green's functions in non-hermitian random matrix models☆
Abstract We review some recent techniques for dealing with non-hermitian random matrix models based on generalized Green's functions. We introduce the diagrammatic methods in the hermitian case and generalize them to the non-hermitian case. The results are illustrated in terms of the eigenvalue distribution, eigenvector statistics and addition laws.
119063881
New Results on the Odderon in QCD
We present our recent results on the odderon intercept in perturbative QCD, obtained through the solution of the Baxter equation and investigation of the spectrum of the relevant constant of motion.
118709171
Janus black holes
In this paper Janus black holes in A dS3 are considered. These are static solutions of an Einstein-scalar system with broken translation symmetry along the horizon. These solutions are dual to interface conformal field theories at finite temperature. An approximate solution is first constructed using perturbation theory around a planar BTZ blackhole. Numerical and exact solutions valid for all sets of parameters are then found and compared. Using the exact solution the thermodynamics of the system is analyzed. The entropy associated with the Janus black hole is calculated and it is found that the entropy of the black Janus is the sum of the undeformed black hole entropy and the entanglement entropy associated with the defect.
123438213
Large size foil-microchannel plate timing detectors
Abstract A large area foil-microchannel plate time-of-flight (TOF) system is presented. The parameters of the system are as follows: 55 cm 2 active area, 99.8% detection efficiency, 100% transparency and 700 ps time resolution. The TOF system, unique in size and conditions of exploitation, consists of two (or three) detectors used also as anticoincidence units for the analysing multistrip Si-detector array.
120714913
Low-pressure drift chamber with a built-in scintillator
Abstract A low-pressure drift chamber with a built-in scintillator has been developed. Pulse height characteristics and the velocity of electrons, drifting in various electric fields in isobutane, have been measured. A standard deviation of the coordinate determined by measuring the drift time of the electrons has been found to be around 100 μm for a 20 mm drift length at 50 Torr of isobutane. A standard deviation of the second coordinate measured by a delay line is better than 100 μm. The work was performed at the High Energy Laboratory, JINR.
120334493
Time Projection Chambers with C-pads for heavy ion tracking
Time Projection Chambers with C-pads and integrated delay line readout were developed as position sensitive detectors for the Fragment separator at GSI Darmstadt. The main advantages of TPCs are a small amount of matter in the sensitive volume, high spatial resolution, and high tracking efficiency. Working parameters in experimental conditions are presented. Internal spatial resolutions of σ x = 88 μ m and σ y = 38 μ m were achieved. The tracking efficiency dependence on ion beam intensity was studied with 238 U beam at 1  GeV/ u energy. Efficiency of more than 99% was achieved up to 40 kHz and over 90% for 250 kHz 238 U beam intensity. Different kinds of ions from proton to uranium were measured in many experiments and confirmed the result obtained.
122883967
Structure of neutron-rich oxygen isotopes
One-nucleon removal reactions at relativistic energies have been used as a spectroscopic tool for obtaining information about the ground state of neutron-rich oxygen isotopes. Using the FRS at GSI, the longitudinal momentum distributions of the emerging fragments after breakup were measured along with the one-nucleon removal cross-sections. The relative contributions of the remaining fragments in their ground and excited states have been determined for a few cases from measurements of γ rays in coincidence with the longitudinal momentum distribution. The controversial case of 23O has been directly addressed. Comparison of our exclusive momentum distributions for the one-neutron removal channel to theoretical momentum distributions calculated with an Eikonal model for the knockout process rendered a spin and parity of Iπ = 1/2+ for the 23O ground state. This result resolves the existent experimental discrepancy and supports sub-shell closure at N = 14 with a fairly pure 2s1/2 neutron in 23O.
8239147
New isomers in the full seniority scheme of neutron-rich lead isotopes: the role of effective three-body forces.
The neutron-rich lead isotopes, up to (216)Pb, have been studied for the first time, exploiting the fragmentation of a primary uranium beam at the FRS-RISING setup at GSI. The observed isomeric states exhibit electromagnetic transition strengths which deviate from state-of-the-art shell-model calculations. It is shown that their complete description demands the introduction of effective three-body interactions and two-body transition operators in the conventional neutron valence space beyond (208)Pb.