Under the assumption that a quark-gluon plasma droplet is produced and its evolution can be described by hydrodynamics in p + A collisions, $γ$-triggered hadron spectra are studied within a next-to-leading-order perturbative QCD parton model with the medium-modified parton fragmentation functions. The initial conditions and space-time evolution of the small QGP droplet are provided by the superSONIC hydrodynamic model simulations and parton energy loss in such a medium is described by the high-twist (HT) approach. The scaled jet transport coefficient $\hat{q}/T^3$ in this HT approach is extracted from single hadron suppression in central A + A collisions at the same colliding energy. Numerical results for this scenario show that $γ$-hadron spectra at $p_{\rm T}^γ=12-40$ GeV/$c$ are suppressed by 5\% $\sim$ 10\% in the most central 0 - 10\% p + Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV. The suppression becomes weaker at higher transverse momentum of the $γ$ trigger. As a comparison, $γ$-hadron suppression in Pb + Pb collisions at $\sqrt{s_{\rm NN}}=2.76$ and 5.02 TeV is also predicted.
We briefly discuss the possible decoherence observed at the LHC emphasizing that the value of the average transverse momentum at \sqrt{s}=7 TeV can be interpreted as a manifestation of the deviation from the mechanism of the transient state of rotating matter.
We obtain a detailed description of all available hadron multiplicity yields in central Pb--Pb collisions at LHC measured in the rapidity interval $|y|<0.5$. We find that the hadronization of the fireball at LHC occurs at nearly identical intensive physical bulk conditions for all centralities similar to those seen already at RHIC.
We show that all central rapidity hadron yields measured in Pb--Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV are well described by the chemical non-equilibrium statistical hadronization model (SHM), where the chemically equilibrated QGP source breaks up directly into hadrons. SHM parameters are obtained as a function of centrality of colliding ions, and we compare CERN Large Hadron Collider (LHC) with Brookhaven National Laboratory Relativistic Heavy Ion Collider (RHIC) results. We predict yields of unobserved hadrons and address anti-matter production. The physical properties of the quark--gluon…
We suggest that the combined effect of screening, gluon-induced dissociation, collisional damping, and reduced feed-down explains most of the sequential suppression of Y(nS) states that has been observed in PbPb relative to pp collisions at sqrt(s_NN) = 2.76 TeV. The suppression is thus a clear, albeit indirect, indication for the presence of a qgp.
Space-time correlations between produced particles, induced by the composite nature of hadrons, imply specific changes in the properties of the correlation functions for identical particles. The expected magnitude of these effects is evaluated using the recently published blast-wave model analysis of the data for $pp$ collisions at $\sqrt{s}$ = 7 TeV.
A kinematic model based on the superposition of p+p collisions, relativistic geometry and final-state hadronic rescattering is used to predict various hadronic observables in \surd sNN = 2.76 TeV Pb+Pb collisions. Predictions for rapidity and transverse momentum distributions, elliptic flow, and two-boson femtoscopy are presented. A short proper time for hadronization is assumed. Previous calculations using this model which were performed for \surd sNN = 200 GeV Au+Au collisions were shown to describe reasonably well the trends of observables in experiments carried out at that energy, giving t…
The ALICE data on light flavor hadron production obtained in $p-Pb$ collisions at $\sqrt{s_{NN}} $ = 5.02 TeV are studied in the thermal model using the canonical approach with exact strangeness conservation. The chemical freeze-out temperature is independent of centrality except for the lowest multiplicity bin, with values close to 160 MeV but consistent with those obtained in $Pb-Pb$ collisions at $\sqrt{s_{NN}}$ = 2.76 TeV. The value of the strangeness non-equilibrium factor $γ_s$ is slowly increasing with multiplicity from 0.9 to 0.96, i.e. it is always very close to full chemical equilibr…
We explore the possibility of observing elliptic flow in low multiplicity events in central pp collisions at LHC energy, $\sqrt{s}$=14 TeV. It is assumed that the initial interactions produces a number of hot spots. Hydrodynamical evolution of two or more hot spots can generate sufficiently large elliptic flow to be accessible experimentally in 4-th order cumulant analysis.
The transverse momentum spectra of secondary pions and kaons, produced in $P+P$ and various central $Pb+Pb$ collisions at $\sqrt{s_{NN}}=2.76$ TeV at LHC, have been analyzed systematically with an approach based on Tsallis non-extensive statistics. The analytical results have been utilized to determine some of the very important thermodynamical parameters bearing characteristic signatures of the partonic medium produced in such collisions.
Using a quark combination model with the equal-velocity combination approximation, we study the production of hadrons with strangeness and charm flavor quantum numbers in Pb+Pb collisions at $\sqrt{s_{NN}}=$5.02 TeV. We present analytical expressions and numerical results for these hadrons' transverse momentum spectra and yield ratios. Our numerical results agree well with the experimental data available. The features of strange and charm hadron production in the quark--gluon plasma at the early stage of heavy ion collisions are also discussed.
At the FERMILAB TEVATRON and CERN LHC accelerators partonic processes reach such a high energy region, where the weak interactions could enter into consideration in the hadron yields through the opening of resonant W and Z exchange diagrams. We investigate these contributions to inclusive charged hadron production in p+p and p+{\bar p} reactions at a few TeV energies, and compare our results to existing CDF and CMS data. We perform a leading order perturbative QCD calculation and include electroweak channels to estimate the order of magnitude of charged hadron excess. The energy dependence of …
We show that the data of $p_{T}$ spectra of $Ω^{-}$ and $ϕ$ at midrapidity in inelastic events in $pp$ collisions at $\sqrt{s}=$ 13 TeV exhibit a constituent quark number scaling property, which is a clear signal of quark combination mechanism at hadronization. We use a quark combination model under equal velocity combination approximation to systematically study the production of identified hadrons in $pp$ collisions at $\sqrt{s}$= 13 TeV. The midrapidity data of $p_{T}$ spectra of proton, $Λ$, $Ξ^{-}$, $Ω^{-}$, $ϕ$ and $K^{*}$ in inelastic events are simultaneously well fitted by the model. …
Assuming that hot spots are formed in initial pp collisions, in a modified Knudsen ansatz, which accounts for the entropy generation in viscous fluid evolution, we have given predictions for elliptic flow in $\sqrt{s}$=14 TeV pp collisions. Predicted flow depends on the number of hot spots and hot spot sizes. If two to four hot spots of size $\approx$0.1 fm are formed in initial pp collisions, in events with multiplicity $n_ {mult}\approx$10-15, modified Knudsen ansatz predicted flow is accessible experimentally in 4th order cumulant method.
In the Israel-Stewart's theory of second order hydrodynamics, we have simulated $\sqrt{s}$=2.76 TeV Pb+Pb collisions. ALICE data for the centrality dependence of charged particles multiplicity, $p_T$ spectra in 0-5% collisions, centrality dependence of integrated and differential elliptic flow are analysed. Analysis indicate that while ALICE data on charged particles multiplicity or $p_T$ spectra do not demand any viscosity, viscosity is demanded by the elliptic flow data. From a simulataneous fit to all the data sets, viscosity to entropy ratio in $\sqrt{s}_{NN}$=2.76 TeV Pb+Pb collisions is …
Direct photon production, in $\sqrt{s_{NN}}$=200 GeV Au+Au and in $\sqrt{s_{NN}}$=2.76 TeV Pb+Pb collisions, are studied in a hydrodynamic model. Ideal hydrodynamic model, initialised to reproduce experimentally charged particle spectra in RHIC and LHC energy, also reproduces the PHENIX and ALICE measurements for the direct photon spectra in Au+Au collisions at RHIC and Pb+Pb collisions at LHC. The model however produces less elliptic flow than in experiment. Discrepancy between experiment and hydrodynamic simulation is comparatively less in Pb+Pb collisions at LHC than in Au+Au collisions at …
We predict the elliptic flow parameter v_2 in U+U collisions at sqrt{s_{NN}}=200 GeV and in Pb+Pb collisions at sqrt{s_{NN}} = 2.76 TeV using a hybrid model in which the evolution of the quark gluon plasma is described by ideal hydrodynamics with a state-of-the-art lattice QCD equation of state, and the subsequent hadronic stage by a hadron cascade model.
We obtain within the statistical hadronization model the hadron yields $dh/dy$ in heavy ion reactions at $\sqrt{s_{NN}} = 2.76$ TeV. We discuss the dependence both on hadronization temperature $T$, and on critical hadronization pressure $P$. We consider observables distinguishing the hadronization models and conditions.
We present predictions for the suppression of B-mesons using AdS/CFT techniques assuming a strongly coupled quark-gluon plasma at $\sqrt{s_{NN}}=2.76$ TeV for central collisions and $\sqrt{s_{NN}}=5.5$ TeV for various centrality classes. We provide estimates of the systematic theoretical uncertainties due to 1) the mapping of QCD parameters to those in $\mathcal N = 4$ SYM and 2) the exact form of the momentum dependence of the diffusion coefficient predicted by AdS/CFT. We show that coupling energy loss to flow increases $v_2$ substantially out to surprisingly large momenta, on the order of $…
We present predictions of the mean multiplicity yields for different centrality classes of Pb-Pb collisions at $\sqrt{s} = 5.02$ TeV at the LHC, obtained using the Monte-Carlo Modified Glauber model (MGM) [1]. Contrary to generally used standard Glauber calculations, the MGM takes into account the energy conservation in the soft particles production. The only one efficient model parameter was tuned and fixed previously (k=0.35) by fitting the available data on multiplicity for all colliding systems up to RHIC energies. The MGM has shown already a good predictive capability for the yields at $\…
Discussions are underway for a high-energy proton-proton collider. Two preliminary ideas are the $\sqrt{s}=33$ TeV HE-LHC and the $\sqrt{s}=100$ TeV VLHC. With Bayesian statistics, we calculate the probabilities that the LHC, HE-LHC and VLHC discover SUSY in the future, assuming that nature is described by the CMSSM and given the experimental data from the LHC, LUX and Planck. We find that the LHC with $300$/fb at $\sqrt{s}=14$ TeV has a $15$-$75%$ probability of discovering SUSY. Should that run fail to discover SUSY, the probability of discovering SUSY with $3000$/fb is merely $1$-$10%$. Wer…
This paper reflects the heavy Higgs scenario where the mass of charged Higgs is equal to or greater than 200 GeV. The CMS observed and expected values of upper limits on the product $σ_H^\pm BR(H^\pm \rightarrow tb^\mp)$, assuming $H^\pm \rightarrow tb^\mp=1$, both at 8 TeV (at integrated luminosity of 19.7 $fb^{-1}$ ) and 13 TeV (at integrated luminosity of 35.9 $fb^{-1}$ ) c.m energies are used. By comparing these expected and observed upper limits with computational values , we find out the expected and observed exclusion regions of charged Higgs parameter space ($ m_H^\pm - tanβ$ space ) i…
Predictions have been compiled for the $p+$Pb LHC runs, focusing on production of hard probes in cold nuclear matter. These predictions were first made for the $\sqrt{s_{_{NN}}} = 5.02$ TeV $p+$Pb run and were later compared to the available data. A similar set of predictions were published for the 8.16~TeV $p+$Pb run. A selection of the predictions are reviewed here.
Predictions and comparisons of hadronic flow observables for Pb+Pb collisions at 2.76 A TeV and 5.02 A TeV are presented using a hydrodynamics + hadronic cascade hybrid approach. Initial conditions are generated via a new formulation of the IP-Glasma model and then evolved using relativistic viscous hydrodynamics and finally fed into transport cascade in the hadronic phase. The results of this work show excellent agreement with the recent charged hadron anisotropic flow measurements from the ALICE collaboration of Pb+Pb collisions at 5.02 A TeV. Event-by-event distributions of charged hadron v…
We provide a reference in proton-proton collisions at the energy of the Pb-Pb 2010 run at the LHC, sqrt(s) = 2.76 TeV, for the pt-differential production cross section of D0, D+, and D*+ mesons in |y| < 0.5, of electrons from heavy flavour decays in |y| < 0.9, and of muons from heavy flavour decays in 2.5 < y < 4. The reference is obtained by applying a pQCD-driven scaling (based on the FONLL calculation) to ALICE preliminary data at sqrt(s) = 7 TeV. In order to validate the procedure, we scale the D meson cross section to sqrt(s) = 1.96 TeV and compare to the corresponding measurements from t…
Possible scenarios in hh collisions in the TeV regions are discussed in full phase space. It is shown that at such high energies one should expect strong KNO scaling violation and a ln(s) increase of the average charged multiplicity of the semi-hard component, resulting in a huge mini-jet production.
It is suggested that the observed excess of muons in studies of $p \bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV arises from the decay of doubly-charged bosons. Such particles are predicted in the 3-3-1 model where the electroweak gauge group is extended to $SU(3) \times U(1)$.
The single inclusive charged hadron pT spectra in Pb-Pb collisions at the LHC, predicted by a combined hydrodynamics+perturbative QCD (pQCD) approach are presented.
The Large Hadron Collider (LHC) recently started operating at 8 TeV. In this note, we update our earlier LHC forward hadronic scattering predictions \cite{physicsreports,update7, blackdisk}, giving new predictions, including errors, for the $pp$ total and inelastic cross sections, the $ρ$-value, the nuclear slope parameter $B$, $dσ_{\rm el}/dt$, and the large gap survival probability at 8 TeV.
Multiplicity, rapidity and transverse momentum distributions of hadrons produced both in inelastic and nondiffractive $pp$ collisions at energies from $\sqrt{s} = 200$\,GeV to 14\,TeV are studied within the Monte Carlo quark-gluon string model (QGSM). Good agreement with the available experimental data up to $\sqrt{s} = 13$\,TeV is obtained, and predictions are made for the collisions at top LHC energy $\sqrt{s} = 14$\,TeV. The model indicates that Feynman scaling and extended longitudinal scaling remain valid in the fragmentation regions, whereas strong violation of Feynman scaling is observe…
We revisit the $J/ψ$ pair production issue at the Fermilab Tevatron Run II with the center-of-mass energy $\sqrt{s}=1.96 \mathrm{TeV}$. Both color-singlet and -octet production mechanisms are considered. Our result shows that the transverse momentum($p_T$) scaling behaviors of double $J/ψ$ differential cross sections in color-singlet and -octet deviate distinctively from each other while $p_T$ is larger than $8 \mathrm{GeV}$, and with the luminosity of ${5 \mathrm{fb^{-1}}}$ the $J/ψ$ pair events from color-singlet scheme are substantially measurable in Tevatron experiments, even with certain …
The transverse momentum spectra for direct photons produced in Pb-Pb collisions at the LHC, including thermal (hydrodynamics) and prompt (pQCD) emissions are presented.
We present results on NLO-QCD corrections to the process e+ e- --> hadrons via photon-, Z- and graviton-exchange in the context of TeV-scale gravity models. The quantitative impact of these QCD corrections for searches of extra dimensions at a Linear Collider is briefly discussed.
We have measured the cross sections $d^2σ/dP_T dη$ for production of isolated direct photons in \pbarp collisions at two different center-of-mass energies, 1.8 TeV and 0.63 TeV, using the Collider Detector at Fermilab (CDF). The normalization of both data sets agree with the predictions of Quantum Chromodynamics (QCD) for photon transverse momentum ($P_T$) of 25 GeV/c, but the shapes versus photon $P_T$ do not. These shape differences lead to a significant disagreement in the ratio of cross sections in the scaling variable $x_T (\equiv 2P_T/\sqrt{s}$). This disagreement in the $x_T$ ratio is d…
First QCD results obtained from the CDF experiment using Run II data are reported. The Run II physics program at the Tevatron started in the spring of 2001, with protons and anti-protons colliding at an energy of sqrt(s) = 1.96 TeV. The size of the data sample already compares to that of Run I. Results presented here include the measurement of the inclusive jet cross section, a search for new particles decaying to dijets, and a study of diffractive dijet events.
Multi-particle transverse energy correlation(MTEC) functions are proposed to study minijet production in high energy proton-antiproton collisions. Obtainable with both the D0 and the CDF detector, the high-order MTEC functions are shown to be sensitive probes of jet internal structure as well as promising observables of detecting minijet production in $\sqrt{s}$=1.8 TeV $p\bar{p}$ collisions.
The investigation of lepton-hadron and photon-hadron collisions at TeV scale is crucial both to clarify the strong interaction dynamics from nuclei to quark-parton level and for adequate interpretation of experimental data from future hadron colliders (LHC and VLHC). In this presentation different TeV scale lepton-hadron and photon-hadron collider proposals (such as THERA, LEP-LHC, QCD Explorer etc) are discussed. The advantages of linac-ring type colliders has been shown comparatively.
We consider the production of high invariant mass jet pairs at hadron colliders as a test for TeV scale gravitational effects. We find that this signal can probe effective Planck masses of about 10 TeV at the LHC with center of mass energy of 14 TeV and 1.5 TeV at the Tevatron with center of mass energy of 2 TeV. These results are compared to analogous scattering processes at leptonic colliders.
We investigate the discovery potential of Kaluza-Klein gluons as a dijet resonance at hadron colliders with different center-of-mass energies, from 14 TeV to 33 TeV to 100 TeV. We also present the current bounds from dijet searches at UA2, Tevatron, and LHC.
Transverse Momentum, $p_T$, spectra is of prime importance in order to extract crucial information about the evolution dynamics of the system of particles produced in the collider experiments. In this work, the transverse momentum spectra of charged hadrons produced in $PbPb$ collision at $5.02$ TeV has been analyzed using different distribution functions in order to gain strong insight into the information that can be extracted from the spectra. We have also discussed the applicability of Pearson distribution on the spectra of charged hadron at $5.02$ TeV.
We estimate differential rapidity cross sections for $J/Ψ$, $Ψ(2S)$, $Υ(1S)$, $Υ(2S)$, and $Υ(3S)$ production; and $Ψ(2S)$ to $J/Ψ(1S)$, $Υ(3S)$ to $Υ(1S)$ suppression via Xe-Xe collisions at proton-proton energy $\equiv \sqrt{s_{pp}}$ =5.44 TeV. For the $Ψ(2S)$, $Υ(3S)$ states we use the mixed heavy quark hybrid theory, with these states being approximately 50\% standard and 50\% hybrid charmonium, bottomonium meson states.
Identified-hadron (PID) $p_t$ spectra from 13 TeV $p$-$p$ collisions are compared with a two-component (soft+hard) model (TCM) that accurately distinguishes jet-related hadron production (hard component) from nonjet projectile-nucleon dissociation (soft component). The present $p$-$p$ study is similar to and is guided by recent TCM studies of PID spectra from 5 TeV $p$-Pb collisions. The combined analyses serve to establish a well-understood quantitative description of PID hadron production in small collision systems as a control experiment. The control can then be contrasted with conventional…
We estimate differential rapidity cross sections for $J/Ψ$, $Ψ(2S)$, $Υ(1S)$, $Υ(2S)$, and $Υ(3S)$ production via Pb-Pb collisions at proton-proton energy $\equiv \sqrt{s_{pp}}$ =5.02 TeV. For the $Ψ(2S)$, $Υ(3S)$ states we use the mixed heavy quark hyrid theory, with these states being approximately 50\% standard and 50\% hybrid charmonium, bottomonium meson states. This is an extension of previous work on heavy quark state production via Cu-Cu and Au-Au collisions at $\sqrt{s_{pp}}$=200 GeV.
We show that the experimental data of $p_T$ spectra of identified hadrons released recently by ALICE collaboration for $p$-Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV exhibit a distinct universal behavior --- the quark number scaling. We further show that the scaling is a direct consequence of quark (re-)combination mechanism of hadronization and can be regarded as a strong indication of the existence of the underlying source with constituent quark degree of freedom for the production of hadrons in $p$-Pb collisions at such high energies. We make also predictions for production of other hadrons.
We discuss production of charm and bottom quarks at forward rapidity in pp collisions at the LHC, updating the QCD predictions for the run at \sqrt{S}=13 TeV. We show that, while the absolute rates suffer from large theoretical systematics, dominated by scale uncertainties, the increase relative to the rates precisely measured at 7 TeV can be predicted with an accuracy of a few percent, sufficient to highlight the sensitivity to the gluon distribution function.
Although transverse-mass scaling of femtoscopic radii is found to hold to a good approximation in heavy-ion collision experiments, it is seen to fail for high-energy proton-proton collisions. It is shown that if invariant radius parameters are plotted versus the transverse velocity instead, scaling with the transverse velocity is seen in $\sqrt{s}=7$ TeV proton-proton experiments. A simple semi-classical model is shown to qualitatively reproduce this transverse velocity scaling.
The intermittency-type fluctuations as outlined by Bialas and Peschanski in the 1980s is analysed in $pp$ collisions at $\sqrt{s}=$ 0.9, 7 and 8 TeV from the CMS collaboration at CERN. Our preliminary analysis shows that the intermittency exponents in the bin-averaged scaled factorial moments decrease in magnitude with increasing collision energy at the TeV scale, which suggests that the cascading nature of multiparticle production described by the $α$-model is weakening. We outline possible areas planned for future studies.
In TeV scale gravity models, for dilepton production at hadron colliders, we present the NLO-QCD corrections for the double differential cross section in the invariant mass and scattering angle. For both ADD and RS models, the quantitative impact of QCD corrections for extra dimension searches at LHC and Tevatron are investigated. We present the K-factors for both ADD and RS models at LHC and Tevatron. Inclusion of QCD corrections to NLO stabilises the cross section with respect to scale variations.
We show that, even for a soft collision like forward elastic scattering, the phase of the amplitude is extremely sensitive to a breakdown of strict causality in local QFT. This is especially the case when the breakdown is manifested by a failure of polynomial boundedness which leads to amplitudes that in some complex direction have order 1 exponential growth in $|\sqrt{s}|$.
We present predictions of single inclusive jet transverse momentum, energy, and Feynman-$x$ spectra at forward rapidity ($5.2 < y < 6.6$) in proton-proton collisions with $\sqrt{s} = 7$ and 13 TeV. Calculations based on high-energy factorization and $k_T$-dependent parton densities are compared to simulations using the \pythia\ event generator. Effects from parton density evolution, parton shower dynamics, multi-parton interactions, and saturation of parton densities are investigated.
We report on a search for direct Kaluza-Klein graviton production in a data sample of 84 ${pb}^{-1}$ of \ppb collisions at $\sqrt{s}$ = 1.8 TeV, recorded by the Collider Detector at Fermilab. We investigate the final state of large missing transverse energy and one or two high energy jets. We compare the data with the predictions from a $3+1+n$-dimensional Kaluza-Klein scenario in which gravity becomes strong at the TeV scale. At 95% confidence level (C.L.) for $n$=2, 4, and 6 we exclude an effective Planck scale below 1.0, 0.77, and 0.71 TeV, respectively.
