What to Expect When You're Expecting: Femtoscopy at the LHC

A huge systematics of femtoscopic measurements have been used over the past 20 years to characterize the system created in heavy ion collisions. These measurements cover two orders of magnitude in energy, and with LHC beams imminent, this range will be extended by more than another order of magnitude. Here, I discuss theoretical expectations of femtoscopy of $A+A$ and $p+p$ collisions at the LHC, based on Boltzmann and hydrodynamic calculations, as well as on naive extrapolation of existing systematics.Comment: 6 pages; 8 figures; Invited talk at the Second Workshop on Particle Correlations and Femtoscopy (WPCF06), Sept 9-11 2006, Sao Paulo, Brazi

Femtoscopy in heavy ion collisions: Wherefore, whence, and whither?

I present a brief overview of the wealth of femtoscopic measurements from the past two decades of heavy ion experiments. Essentially every conceivable knob at our disposal has been turned; the response of two-particle correlations to these variations has revealed much about he space-momentum substructure of the hot source created in the collisions. I discuss the present status of the femtoscopic program and questions which remain, and point to new efforts which aim to resolve them.Comment: 12 pages, 11 figures; Combined write-up of presentations at XXXV International Symposium on Multiparticle Dynamics, and at the Workshop on Particle Correlations and Femtoscopy, Kromeriz, Czech Republic, August 200

Global Conservation Laws and Femtoscopy of Small Systems

It is increasingly important to understand, in detail, two-pion correlations measured in p+p and d+A collisions. In particular, one wishes to understand the femtoscopic correlations, in order to compare to similar measurements in heavy ion collisions. However, in the low-multiplicity final states of these systems, global conservation laws generate significant N-body correlations which project onto the two-pion space in non-trivial ways and complicate the femtoscopic analysis. We discuss a model-independent formalism to calculate and account for these correlations in measurements.Comment: 7 pages; 10 figures; Invited talk at the Second Workshop on Particle Correlations and Femtoscopy (WPCF06), Sept 9-11 2006, Sao Paulo, Brazi

Azimuthally-sensitive pion HBT at RHIC

The STAR Collaboration has measured two-pion correlation functions versus emission angle with respect to the event plane in non-central Au+Au collisions at \sqrt{s_{NN}}=130, 200 GeV. In the context of a parameterized freezeout scenario, the data suggest an out-of-plane freezeout geometry, and a rapid system evolution to freezeout.Comment: presented at XXXII International Symposium on Multiparticle Dynamics (ISMD2002), Alushta, Ukraine; to appear in the proceeding

Conservation Laws and the Multiplicity Evolution of Spectra at the Relativistic Heavy Ion Collider

Transverse momentum distributions in ultra-relativistic heavy ion collisions carry considerable information about the dynamics of the hot system produced. Direct comparison with the same spectra from $p+p$ collisions has proven invaluable to identify novel features associated with the larger system, in particular, the "jet quenching" at high momentum and apparently much stronger collective flow dominating the spectral shape at low momentum. We point out possible hazards of ignoring conservation laws in the comparison of high- and low-multiplicity final states. We argue that the effects of energy and momentum conservation actually dominate many of the observed systematics, and that $p+p$ collisions may be much more similar to heavy ion collisions than generally thought.Comment: 15 pages, 14 figures, submitted to PRC; Figures 2,4,5,6,12 updated, Tables 1 and 3 added, typo in Tab.V fixed, appendix B partially rephrased, minor typo in Eq.B1 fixed, minor wording; references adde

Cosmological Evolution of the Universe Neutral Gas Mass Measured by Quasar Absorption Systems

The cosmological evolution of neutral hydrogen is an efficient way of tracing structure formation with redshift. It indicates the rate of evolution of gas into stars and hence the gas consumption and rate star formation history of the Universe. In measuring HI, quasar absorbers have proven to be an ideal tool and we use observations from a recent survey for high-redshift quasar absorption systems together with data gathered from the literature to measure the cosmological comoving mass density of neutral gas. This paper assumes Omega_M=0.3, Omega_lambda=0.7 and h=0.65.Comment: 3 pages, 2 figures. To appear in the proceedings of the "Cosmic Evolution" conference, held at l'Institut d'Astrophysique de Paris, November 13-17, 200

HBT radii from the UrQMD transport approach at different energies

We present results on Hanbury Brown-Twiss (HBT) radii extracted from the Ultra-relativistic Molecular Dynamics (UrQMD) approach to relativistic heavy ion collisions. The present investigation provides a comparison of results from pure hadronic transport calculations to a Boltzmann + Hydrodynamic hybrid approach with an intermediate hydrodynamic phase. For the hydrodynamic phase different Equations of State (EoS) have been employed, i.e. bag model, hadron resonance gas and a chiral EoS. The influence of various freeze-out scenarios has been investigated and shown to be negligible if hadronic rescatterings after the hydrodynamic evolution are included. Furthermore, first results of the source tilt from azimuthal sensitive HBT and the direct extraction from the transport model are presented and exhibit a very good agreement with E895 data at AGS

A Comparison of Two Commercial Swim Bench Ergometers in Determining Maximal Aerobic Power and Correlation to a Paddle Test in a Recreational Surfing Cohort

The recent addition of surfing to the Tokyo 2020 Olympic Games has fueled a surge in commercial and research interest in understanding the physiological demands of the sport. However, studies specific to maximal aerobic testing of surfers are scarce. Therefore, the primary aim of this study was to compare two commercially available swim bench (SWB) ergometers in the determination of maximal aerobic capacity in recreational surfers. A secondary aim was to correlate (independent of one another) the two ergometer findings of VO2peak to the time taken to complete a water-based 400-m paddle test. This cross-sectional study consisted of 17 recreational surfers aged between 18–58 years. Participants were randomized to either the SwimFast ergometer or VASA ergometer and tested for maximal aerobic capacity, followed by a 400-m paddle test. There were no significant differences between the two SWB ergometers in the determination of relative VO2peak (mean difference 0.33 mL/kg/min; 95% CI −1.24–1.90; p = 0.66). Correlations between VO2peak obtained from maximal paddling effort on the SwimFast and the VASA and the 400-m paddle test (total time (s)) showed a negative significant correlation r = −0.819, p = 0.024; r = −0.818, p = 0.024, respectively. Results suggest that either ergometer (SwimFast or VASA) can be used to determine peak aerobic capacity within a recreational surfing cohort. The significant correlation of the two SWB ergometers and the 400-m paddle test suggest that the 400-m paddle test may be a suitable field-based method of determining aerobic capability. Collectively, these preliminary findings provide initial evidence for similarities in VO2peak on two commercial ergometers and their correlations with a field-based test. However, further research is needed with a larger sample size and inclusive of competitive surfers to provide robust findings which can be generalized to the surfing population