Black Holes at LHC?

Strategies for identifying speculative mini black hole events (due to large extra dimensions) at future colliders are reviewed. Estimates for production cross sections, Hawking radiation, di-jet suppression and multi- mono-jet emission are surveyed. We further report on a class of effective entropy formulas that could lead to the formation of a final black hole remnant state, BHR. Such BHRs could be both electrically charged and uncharged. Charged BHRs should be observable by single stiff charged tracks in the detectors. Collinear hadronic jets with a large missing transverse momentum are presented as new observable signal for electrically neutral black holes.Comment: added references to old version, 9 pages, accepted at J. Phys.

A machine learning study to identify spinodal clumping in high energy nuclear collisions

The coordinate and momentum space configurations of the net baryon number in heavy ion collisions that undergo spinodal decomposition, due to a first-order phase transition, are investigated using state-of-the-art machine-learning methods. Coordinate space clumping, which appears in the spinodal decomposition, leaves strong characteristic imprints on the spatial net density distribution in nearly every event which can be detected by modern machine learning techniques. On the other hand, the corresponding features in the momentum distributions cannot clearly be detected, by the same machine learning methods, in individual events. Only a small subset of events can be systematically differ- entiated if only the momentum space information is available. This is due to the strong similarity of the two event classes, with and without spinodal decomposition. In such sce- narios, conventional event-averaged observables like the baryon number cumulants signal a spinodal non-equilibrium phase transition. Indeed the third-order cumulant, the skewness, does exhibit a peak at the beam energy (Elab = 3–4 A GeV), where the transient hot and dense system created in the heavy ion collision reaches the first-order phase transition

Three-Particle Azimuthal Correlations

Two-particle azimuthal correlations in central Au+Au collisional at RHIC have revealed a broadened away-side structure, with respect to perpherial Au+Au, pp, and d+Au. This could be explained by different physics mechanisms such as: large angle gluon radiation, deflected jets, Cerenkov gluon radiation, and conical flow generated by hydrodynamic shock-waves. We can discriminate the scenarios with conical emission, Cerenkov radiation and conical flow, from the other mechanisms though three-particle correlations. In addition, the associated particle pT dependence can be used to distinguish conical flow from simple Cerenkov gluon radiation. We will discuss three-particle correlation analyses that have been performed at RHIC and what can be done at the LHC.Comment: Talk given at 'High p_T physics at the LHC', Jyvaskyla, Finland, March 200

Constraining baryon annihilation in the hadronic phase of heavy-ion collisions via event-by-event fluctuations

We point out that the variance of net-baryon distribution normalized by the Skellam distribution baseline, $\kappa_2[B-\bar{B}]/\langle B+\bar{B}\rangle$, is sensitive to the possible modification of (anti)baryon yields due to $B\bar{B}$ annihilation in the hadronic phase. The corresponding measurements can thus place stringent limits on the magnitude of the $B\bar{B}$ annihilation and its inverse reaction. We perform Monte Carlo simulations of the hadronic phase in Pb-Pb collisions at the LHC via the recently developed subensemble sampler + UrQMD afterburner and show that the effect survives in net-proton fluctuations, which are directly accessible experimentally. The available experimental data of the ALICE Collaboration on net-proton fluctuations disfavors a notable suppression of (anti)baryon yields in $B\bar{B}$ annihilations predicted by the present version of UrQMD if only global baryon conservation is incorporated. On the other hand, the annihilations improve the data description when local baryon conservation is imposed. The two effects can be disentangled by measuring $\kappa_2[B+\bar{B}]/\langle B+\bar{B}\rangle$, which at the LHC is notably suppressed by annihilations but virtually unaffected by baryon number conservation.Comment: 6 pages, 4 figure

The rapidity structure of Mach cones and other large angle correlations in heavy-ion collisions

The pattern of angular correlations of hadrons with a (semi-)hard trigger hadron in heavy-ion collisions has attracted considerable interest. In particular, unexpected large angle structures on the away side (opposite to the trigger) have been found. Several explanations have been brought forward, among them Mach shockwaves and Cherenkov radiation. Most of these scenarios are characterized by radial symmetry around the parton axis, thus angular correlations also determine the rapidity dependence of the correlation. If the observed correlations are remnants of an away side parton after interaction with the medium created in the collision, pQCD allows to calculate the distribution $P(y)$ of the away side partons in rapidity. The measured correlation then arises as a folding of $P(y)$ and the rapidity structure of the correlation taking into account the detector acceptance. This places non-trivial and rather stringent constraints on the underlying scenario. We investigate these dependences and demonstrate that Mach shockwaves survive this folding procedure well whereas Cherenkov radiation scenarios face new challenges.Comment: 9 pages, 3 figures, version to appear in Phys. Lett.

Analysis Method for Jet-Like Three-Particle Azimuthal Correlations

Jet-like three-particle azimuthal correlations can discriminate various physical scenarios that have been proposed to explain the observed strong modification to two-particle azimuthal correlations. The three-particle correlation analysis is notoriously difficult in heavy-ion collisions due to the large combinatoric backgrounds. We describe the general idea behind the jet-like three-particle azimuthal correlation analysis, with emphasis put on the subtraction of the combinatoric backgrounds. We discuss in detail the various systematic effects in such an analysis.Comment: This is the final published version in NIM

Effectiveness of inpatient versus outpatient complex treatment programs in depressive disorders: a quasi-experimental study under naturalistic conditions.

Driessen M, Schulz P, Jander S, et al. Effectiveness of inpatient versus outpatient complex treatment programs in depressive disorders: a quasi-experimental study under naturalistic conditions. BMC psychiatry. 2019;19(1): 380.BACKGROUND: Due to long waiting periods for outpatient psychotherapy and the high resource requirements of inpatient treatment, there is a need for alternative treatment programs for patients with depressive disorders. Thus, we investigated the effectiveness of the "Bielefeld Outpatient Intensive Treatment Program of Depression" (BID) in comparison with a typical inpatient treatment program by using a prospective quasi-experimental observational study. We assumed (i) that both complex programs are effective in pre-post analyses after 6 weeks and (ii) that inpatient treatment is more effective compared with the outpatient program.; METHODS: Four hundred patients with depressive psychopathology - a majority with depressive episodes (ICD-10 F3X) - took part in the BID and 193 in the inpatient program. Different self- (i.e., BDI) and expert measures (i.e., MADRS) of psychopathology at baseline (t1) and 6 weeks later (t2) were applied to examine treatment effects.; RESULTS: Treatment effects were high in separate analyses of both groups with Cohen's d ranging from 1.10 to 1.76., while ANOVA comparative analyses did not reveal any significant differences between both treatment settings nor did a set of independent covariates analyzed here. Response rates of BDI (p=.002) and MADRS (p=.001) were higher in the outpatient group. Results indicate BID not to be inferior compared to an inpatient program, although diverging pathways to treatment, higher rates of clinical recurrent depressive disorders and severe episodes as well as lower rates of employment and partnership in the inpatient treatment group have to be considered.; CONCLUSION: Outpatient intensive treatment programs may represent a solution for patients needing more than a treatment session once per week but less than a complex inpatient or day clinic program

Hard Probes are the "Meridian Line", sQGP is the Forbidden City

Relativistic heavy-ion collisions at BNL/RHIC have created a hot and dense nuclear matter, the strongly interacting Quark-Gluon Plasma (sQGP). Hard probes, high transverse momentum particles and jets, interact with the sQGP medium and lose energy. The interactions modify the properties of the hard probes; the medium responds to the energy loss of those probes in a collective way. Many properties of the sQGP have been learned from the modifications to the probes and the medium responses. I will review jet-like correlation results from RHIC, especially those measured by three-particle correlations, and discuss some of the fascinating physics.Comment: Invited plenary talk at the 10th International Conference on Nucleus-Nucleus Collisions 200

Jet reshaping in heavy-ion collisions

We propose a new implementation of medium effects in jet structures in which a modification of the splitting function is included at every step in the typical final state parton shower. Although the main application of this new formalism will be at the LHC, it is interesting that, in the presence of a trigger bias to small number of splittings, non-trivial angular dependences could appear with shapes similar to those measured experimentally at RHIC in high-pT particle correlations.Comment: 4 pages, 4 figures, Invited talk at the 37th International Symposium on Multiparticle Dynamics, LBNL, August 200

RHIC results from LHC perspectives

RHIC data opens new ways of characterizing the medium created in a heavy ion collision by measuring particles with high transverse momentum. In addition to the observation of the predicted jet quenching, the new data on particle correlations indicate that a strong modification of the jet-like shapes is driven by the dynamical properties of the medium. I will review the lessons we are learning from RHIC and outline some new directions which could become of primary importance at the LHC.Comment: 10 pages, 5 figures. Plenary talk given at Quark Matter 2005 Conference, Budapest, Hungary, 4-9 Aug 200