S. M. Troshin, N. E. Tyurin
We discuss interpretation of the reflective scattering mode connecting its appearance with a resolution of a two--scale structure of a proton revealed in the DVCS process at Jefferson laboratory and in the differential cross--section of elastic $pp$--scattering at the LHC at the energy of $\sqrt{s}=13$ TeV.
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The specific effects of the reflective scattering (antishadowing) related to the spin correlations in the top quark production at the LHC are considered. Account for those effects is important in the searches for the signatures of the extra dimensiones. It is shown that significant spin correlations could arise at the LHC energies due to reflective scattering and those can affect the signals of the extra dimensions.
We discuss effects of reflective scattering for hadron and heavy nuclei collisions at the LHC and asymptotical energies. It is shown that the reflective scattering might lead to decreasing matter density with energy beyond the LHC energies. Limiting form of energy dependence of hadron density is obtained. Unitarity upper bound for the absolute value of the real part of elastic scattering amplitude and two-particle inelastic binary reactions amplitudes in impact parameter representation is two times less than the corresponding bound for the imaginary part of the elastic scattering amplitude. Th…
We discuss the high-energy dependencies of diffractive and non-diffractive inelastic cross-sections in view of the recent LHC data which revealed a presence of the reflective scattering mode.
Interpretation of unitarity saturation as reflective scattering is discussed. Analogies with optics and Berry phase alongside with the experimental consequences of the proposed interpretation at the LHC energies are considered.
We discuss effects of reflective scattering for heavy nuclei collisions and the deconfined matter formation at the LHC and asymptotical energies. Reflective scattering in hadron collisions leads to decreasing matter density with energy beyond the LHC energies. Limiting form of energy dependence of hadron density is obtained.
Reflective ability and its energy dependence
本文引入反射能力概念，利用有理形式幺正化研究其能量依赖，指出反射能力增强始于LHC能区，并给出数值估计。
Multiplicity distribution under the reflective scattering mode
本文研究LHC最高能量下反射散射模式对多重数分布的影响，指出非弹性碰撞参数区域随能量收缩，并强调量子起源的多重数涨落作用增强。
We point out the several experimental manifestations of the new reflective scattering mode in elastic scattering and multiparticle production at the LHC energy range.
The reflective scattering mode is supposed to play a significant role in hadron interactions at the LHC energy region and beyond. We discuss connection of this mode to the color conducting medium formation in hadron collisions and its role in centrality determination. The issues of centrality in view of the measurements at the LHC are relevant for enlightening the asymptotic dynamics.
Proceeding from optical analogy we propose a new physical interpretation of unitarity saturation leading to antishadowing as a reflective scattering. This interpretation of antishadowing is related to the non-perturbative aspects of strong interactions and follows from the specific property of the unitarity saturation when elastic $S$-matrix $S(s,b)|_{b=0}\to -1$ at $s\to \infty$. The analogy with Berry phase and experimental consequences of the proposed interpretation as reflective scattering at the LHC and in the cosmic rays studies are discussed.
We discuss various aspects of the multiparticle production processes at the LHC energy range with emphasis on the collective effects associated with appearance of the new scattering mode, which corresponds to the reflective scattering and its impact on multiparticle production processes.
This is a short communication with a summary of results obtained with a model based on Gribov's reggeon calculus, which was proposed and applied to processes of soft diffraction at high energies. We present a brief description of the model and its predictions for various LHC energies.
We consider the simultaneous production of two heavy-flavoured hadrons - particularly D mesons - at the LHC. We base our calculations on collinearly factorized QCD at next-to-leading order, using the contemporary parton distribution functions and D-meson fragmentation functions. The contributions of double-parton scatterings are included in the approximation of independent partonic interactions. Our framework benchmarks well with the available proton-proton data from the LHCb collaboration giving us confidence to make predictions for proton-lead collisions. Our results indicate that the double…
Absence of the signals of the physics beyond the Standard Model at the available LHC energies means that the several of cosmic data peculiarities could be associated with an emergency of the new scattering mode. This reflective scattering mode can be used for explanations of the measurements performed under the study of extensive air showers (EAS).
We compute the proton-proton multiplicity distributions at LHC energies in the framework of a multiple scattering model assuming a Poisson distribution for each inelastic collision. Multiple scattering is essential to broaden the multiplicity distribution. We obtain approximate KNO scaling for small pseudo-rapidity intervals ($|η| < 0.5$) and sizable KNO scaling violations for larger ones, in agreement with experiment.
We discuss thw relations between the elastic and inelastic cross-sections valid for the shadow and reflective modes of the elastic scattering. Considerations are based on the unitarity arguments. It is shown that the redistribution of the total interaction probability between the elastic and inelastic interactions can lead to increasing ratio of $σ_{el}(s)/σ_{tot}(s)$ at the LHC energies in presence of the reflective scattering mode. The form of the inelastic overlap function becomes peripheral due to the negative feedback. In the absorptive scattering mode, the mechanism of this increase is a…
For the energy of 14 TeV, to be reached at the Large Hadron Collider (LHC), we have had for some time accurate predictions for both the real and imaginary parts of the forward proton-proton elastic scattering amplitude. LHC is now scheduled to start operating in two years, and it is timely to discuss some of the important consequences of the measurements of both the total cross-section and the ratio of the real to the imaginary part. We stress the importance of measuring the real part of the proton-proton forward scattering amplitude at LHC, because a deviation from existing theoretical predic…
We argue that string percolation is in the origin of i) an approximately flat rapidity distribution and of ii) an approximately constant forward-backward correlation parameter $b$ over a substantial fraction of the available rapidity. Predictions are given for $pp$ collisions at LHC, $\sqrt{s}=14$TeV and $\sqrt{s}=5.5$TeV.
I present a brief review of present CGC phenomenological applications and of the physics prospects for the forthcoming proton-lead run at the LHC
A model for exclusive diffractive resonance production in proton-proton collisions at LHC energies is presented. This model is based on the convolution of the Donnachie-Landshoff parameterisation of Pomeron flux in the proton with the Pomeron cross section for resonance production. The hadronic cross section for f$_{0}$(980) and f$_{2}$(1270) production at midrapidity is given differentially in mass and transverse momentum of the resonance. The proton fractional longitudinal momentum loss is presented.
A short review on charmed and beauty hadron production in the lepton deep inelastic scattering off proton, in proton-proton and proton-antiproton collisions at high energies is presented. It is shown that the existing theoretical and experimental information on charmed and beauty quark distributions in a proton is not satisfactory. A some procedure to study these distributions at LHC energies is suggested.
We review the theoretical and experimental motivations behind recent proposals to add forward proton tagging detectors to the LHC experiments as a means to search for new physics.
We present results for final state charged particle (pseudo-)rapidity distributions in $\rm{p}$ + $\bar{\rm{p}}$ / $\rm{p}$ + $\rm{p}$ and Pb+Pb/Au+Au at ultra high energies (17.3 GeV $\leq$ $\sqrt{s_{\rm{NN}}}$ $\leq$ 14 TeV) from the Ultra-relativistic Quantum Molecular Dynamics (UrQMD-v2.3) model. In addition, excitation functions of produced charged particle multiplicities ($N_{\rm{ch}}$) and pseudorapidity spectra are investigated up to LHC energies. Good agreement is observed between UrQMD and measured pseudorapidity distributions of charged particles up to the highest Tevatron and Sp$\b…
A recent Schwinger Generating Functional based formulation, by H.M.Fried,Y.Gabellini,T.Grandou and Y-M.Sheu and P.H.Tsang provided gauge-invariant, exact, non-perturbative solutions for QCD. After choosing a renormalization scheme and assuming a simpler 2 body quark-quark scattering problem, this formalism is tested against experimental elastic proton-proton scattering at LHC energies (7, 8, 13 TeV). This formulation was previously compared with ISR energies at (23.5 - 62.5 GeV). The full scattering amplitude with infinite gluons summed, infinite loops summed and their interference terms are n…
We present some physics topics that can be studied at the LHC using proton tagging. We distinguish the QCD (Pomeron structure, BFKL analysis...) from the exploratory physics topics (HIggs boson, anomalous couplings between photons and $W/Z$ bosons
We present some inclusive and exclusive diffractive processes to be studied at the LHC, namely QCD, quartic anomalous couplings between $γ$ and $W/Z$ bosons and diffractive Higgs processes.
Using nonrelativistic QCD (NRQCD) factorization, we calculate the yields for $J/ψ$, $ψ(2S)$ and $Υ(1S)$ hadroproduction at $\sqrt{s}=$ 72 GeV and 115 GeV including the next-to-leading order QCD corrections. Both these center-of-mass energies correspond to those obtained with 7~TeV and 2.76~TeV nucleon beam impinging a fixed target. We study the cross section integrated in $p_t$ as a function of the rapidity as well as the $p_t$ differential cross section in the central rapidity region. Using different NLO fit results of the NRQCD long-distance matrix elements, we evaluate a theoretical uncerta…
Transverse momentum dependent gluon distributions encode fundamental information on the structure of the proton. Here we show how they can be accessed in heavy quarkonium production in proton-proton collisions at the LHC. In particular, their first determination could come from the study of an isolated J/psi or Upsilon particle, produced back to back with a photon.
We present some physics topics that can be studied at the LHC using proton tagging. We distinguish the QCD (Pomeron structure, BFKL analysis...) from the exploratory physics topics (HIggs boson, anomalous couplings between photons and $W/Z$ bosons)
Drell-Yan W/Z electroweak boson production at the LHC is an essential standard candle which is used for calibration of beam luminosity and detector properties. In addition to proton-proton collisions, the LHC has measured heavy nuclei lead-lead and proton-lead W/Z production. Inclusion of these data sets in future fits can provide discriminating information of the nuclear modifications present in the Parton Distribution Functions (PDFs). We present an ongoing analysis of W/Z production in lead-lead and proton-lead collisions at the LHC using the \texttt{nCTEQ15} nuclear Parton Distribution Fun…
The LHC data on the forward heavy flavour hadron production can be a new unique source for estimation of intrinsic charm and bottom contributions to the proton. For example, we analyze the forward heavy baryon production, namely $Λ_b$-baryon, within the soft QCD quark gluon string model and present the predictions for observables which could be measured at the LHC. We also present some predictions for the $D$-meson production in $pp$ collisions made within the perturbative QCD including the intrinsic charm in the proton that can be verified at the LHC.
Cross sections for the production of pairs of photons plus two additional jets produced from double parton scattering in high-energy proton-proton collisions at the LHC are calculated for the first time. The estimates are based on the theoretical perturbative QCD predictions for the productions of γγat next-to-next-to-leading-order, jet + jet and γ+ jet at next-to-leading-order, for their corresponding single-scattering cross sections. The cross sections and expected event rates for γγ+ 2 jets from double parton scattering, after typical acceptance and selections, are given for proton-proton c…
We review the theoretical and experimental motivations behind recent proposals to add forward proton tagging detectors to the LHC experiments as a means to search for new physics. We also review the current diffractive programs at the Tevatron and HERA, focusing in particular on measurements which will have a direct impact on the case for forward detectors at the LHC.
Using the framework of leading order perturbative QCD along with the CTEQ6L1 gluon distribution of the proton and high-energy HERA data on the $γp \to J/ψp$ and $γp \to ψ(2S) p$ cross sections along with the corresponding H1 fit, we obtain a good description of the rapidity dependence of the cross sections of photoproduction of $J/ψ$ or $ψ(2S)$ mesons in proton--proton ultraperipheral collisions (UPCs) measured by the LHCb collaboration at the LHC. Within the same framework we also make predictions for the $pp \to pp J/ψ$ and $pp \to pp ψ(2S)$ UPC cross sections at $\sqrt{s_{NN}}=8$ and 14 TeV…
A QCD interpretation of the scaling observed in the LHC proton-proton elastic cross-sections at moderate transfer momentum
本文用QCD饱和框架解释LHC质子-质子弹性散射在中等转移动量下的标度现象，指出硬振幅经幺正化构成pp振幅，且标度指数支持饱和标度指数约为硬过程二分之一的QCD饱和方法。
In this paper, we show that the distribution of the longitudinal momentum fraction of charged hadrons $dN/dz$ inside jets stemming from proton-proton collisions at $\sqrt{s}$ = 7 TeV center of mass energy can be described by a statistical jet-fragmentation model. This model combines microcanonical statistics and super-statistics induced by multiplicity fluctuations. The resulting scale dependence of the parameters of the model turns out to be similar to what was observed in electron-positron annihilations in Urmossy, Barnaföldi, and Biró.
To settle the question whether the growth with energy is universal for different hadronic total cross-sections, we present results from theoretical models for pion-proton, proton-proton and proton-antiproton total cross-sections. We show that present and planned experiments at LHC can differentiate between different models, all of which are consistent with presently available (lower energy) data. This study is also relevant for the analysis of those very high energy cosmic ray data which require reliable pion-proton total cross-sections as seeds. A preliminary study of the total pion-pion cros…
The inclusive large-$p_T$ production of a single pion, jet or direct photon, and Drell-Yan processes, are considered for proton-proton collisions in the kinematical range expected for the fixed-target experiment AFTER, proposed at LHC. For all these processes, predictions are given for the transverse single-spin asymmetry, $A_N$, computed according to a Generalised Parton Model previously discussed in the literature and based on TMD factorisation. Comparisons with the results of a collinear twist-3 approach, recently presented, are made and discussed.
We study the contribution from double parton scattering (DPS) to four-jet production at the LHC, both at the leading order accuracy and after incorporating the effects of QCD radiation. Apart from DPS, we also include and discuss the contribution from single parton scattering (SPS). We find that the QCD radiation impacts theoretical predictions significantly, with DPS contributions more affected than the SPS. We also examine a number of observables in regard to their effectiveness for discrimination between DPS and SPS events and propose sets of kinematical cuts to improve the prospects of mea…
We construct a model for double parton distribution functions (dPDFs) based on the notion of self-similarity, pursued earlier for small \textit{x} physics at HERA. The most general form of dPDFs contains total thirteen parameters to be fitted from data of proton-proton collision at LHC. It is shown that the constructed dPDF does not factorize into two single PDFs in conformity with QCD expectation, and it satisfies the condition that at the kinematic boundary $x_{1}+x_{2}=1 $ (where $x_{1}$ and $x_{2}$ are the longitudinal fractional momenta of two partons), the dPDF vanishes.
We review the prospects for Central Exclusive Diffractive (CED) production of Higgs bosons in the SM with a fourth generation of fermions at the LHC using forward proton detectors installed at 220m and 420m distance around ATLAS and / or CMS. We discuss the determination of Higgs spin-parity and coupling structures at the LHC and show that the forward proton mode would provide a critical information on the CP properties of the Higgs bosons.
The TOTEM Collaboration has measured the differential cross section of elastic proton-proton scattering $\mathrm{d}σ/\mathrm{d}|t|$ at $\sqrt{s} = 2.76$, 7, 8, and 13 TeV. It is observed that all $\mathrm{d}σ/\mathrm{d}|t|$ data points vary in the same way as a function of the center-of-mass energy in the so-called "dip" and "bump" regions. These features hint at possible universal properties of elastic scattering. Based on these empirical observations, and taking inspiration from saturation models, we propose a simple scaling law for proton-proton elastic scattering at LHC energies. We find t…
We examine the potential of pp-> p gamma p -> p W q X reaction to probe anomalous WWgamma couplings at the LHC. We find 95% confidence level bounds on the anomalous coupling parameters with various values of the integrated luminosity. We show that the reaction pp -> p gamma p -> p W q X at the LHC highly improve the current limits.
The prospects for central exclusive diffractive (CED) production of BSM Higgs bosons at the LHC are reviewed. This comprises the production of MSSM and 4th generation Higgs bosons. The sensitivity of the searches in the forward proton mode for the Higgs bosons as well as the possibility of a coupling structure determination are briefly discussed.
The LHC has already provided many relevant measurements for the determination of parton distribution functions (PDFs). Measurements of the W and Z lepton distributions are of interest for flavor separation and in particular for the determination of the relatively poorly constrained strange quark distribution. In this contribution we shall discuss the computational developments that allow for the efficient inclusion of LHC data into the NNPDF framework consistently at NLO for all observables, and we study the constraints of the LHC W and Z data on the strangeness content of the proton.
KNO-like scaling within a jet in proton--proton collisions at LHC energies
本研究通过PYTHIA 8模拟发现，LHC能量下质子-质子碰撞的喷注内带电强子多重数满足KNO标度，该标度在无MPI时成立、有MPI且无色重连时失效，揭示了高能碰撞中部分子簇射或MPI对标度的破坏作用。
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…
In this work we estimate the heavy quark production in proton-proton and proton-nucleus collisions at LHC energies using the color dipole formalism and the solution of the running coupling Balitsky-Kovchegov equation. Nuclear effects are considered in the computation of the total cross sections and rapidity distributions for scattering on protons and nuclei.
Rapidity distributions of vector mesons are computed in dipole model proton-lead ultraperipheral collisions(UPCs) at the CERN Larger Hadron Collider(LHC). The dipole model framework is implemented in the calculations of cross sections in the photon-hadron interaction. The bCGC model and Boosted Gaussian wave functions are employed in the scattering amplitude. We obtain predictions of rapidity distributions of $J/ψ$ meson proton-lead ultraperipheral collisions. The predictions give a good descriptions to the experimental data of ALICE. The rapidity distributions of $ϕ$, $ω$ and $ψ(2s)$ mesons i…
The production of charmed and beauty hadrons in proton-proton collisions at high energies are analyzed within the modified quark-gluon string model (QGSM) including the internal motion of quarks in colliding hadrons. We present some predictions for the future experiments on the beauty baryon production in $pp$ collisions at LHC energies. This analysis allows us to find interesting information on the Regge trajectories of the heavy (b{\bar b}) mesons and the sea beauty quark distributions in the proton.
A gradual transition to the reflecting scattering mode developing already at the LHC energies is affecting multiparticle production dynamics, in particular, relation of the centrality with the impact parameter values of $pp$--collisions. We discuss the issues in the framework of the geometrical picture for the multiparticle production processes proposed by Chou and Yang. We consider effects of reflective scattering mode presence for the inclusive cross-sections.
The ratios of particle densities in lead-lead and proton-lead collisions to particle density in proton-proton collision in the central rapidity region at the LHC energy are predicted on the basis of wounded quark-diquark model.
From the very early days of Particle Physics, both experimental and theoretical studies on proton-proton collisions had occupied the center-stage of attention for very simple and obvious reasons. And this intense interest seems now to be at peak value with the onset of the Large Hadron Collider (LHC)-studies at TeV ranges of energies. In this work, we have chosen to analyse the inclusive cross-sections, the rapidity density, the $K/π$ and $p/π$-ratio behaviours and the $<p_T>$-values, in the light of the Sequential Chain Model (SCM). And the limited successes of the model encourage us to take …
In this paper we consider the soft processes at LHC energies in the framework of the Constituent Quark Model (CQM). We show that this rather naive model is able to describe all available soft data at lower energies and to predict the behavior of the total cross section, elastic and diffractive cross sections at the LHC energy. It turns out that the ''input'' Pomeron, which has been used in this approach, has parameters that are close to so called ''hard'' Pomeron with rather large intercept $Δ\approx 0.12$ and small value of the slope $α'_P \approx 0.08 GeV^{-2}$. We show that the elastic ampl…
A sizable rate of events, with several pairs of $b$-quarks produced contemporarily by multiple parton interactions, may be expected at very high energies as a consequence of the large parton luminosities. The production rates are further enhanced in hadron-nucleus reactions, which may represent a convenient tool to study the phenomenon. We compare the different contributions to $b{\bar b}b{\bar b}$ production, due to single and double parton scatterings, in collisions of protons with nuclei at the CERN-LHC.
Multiple Reflection Expansion (MRE) formalism has been applied to hadron resonance gas (HRG) model to study the finite-size effect on thermodynamics of small systems of hadron gas at the chemical freeze-out temperature in high-multiplicity events of proton-proton (pp) colisions at the LHC. Comparison with larger systems of heavy-ion (AA) collisions helps in undersanding the usefulness of the effect on small systems. Thermodynamic properties of these systems at the chemical freeze-out, with and without system-size effect, are contrasted with those for infinite hadronic phase of strongly interac…
In this paper we present a comparative study between PYTHIA, EPOS, QGSJET, and SIBYLL generators. The global event observables considered are the charged energy flow, charged-particle distributions, charged-hadron production ratios and $V^{0}$ ratios. The study is performed in the LHCb and TOTEM fiducial phase-spaces on minimum bias simulated data samples for \emph{pp} collisions at $\sqrt{s} = 7$ TeV using reference measurements from the aforementioned experiments. In the majority of cases, the measurements are within a band defined by the most extreme predictions. The observed differences be…
We show that exclusive double-diffractive Higgs production, pp -> p+H+p, followed by the H -> bbbar decay, could play an important role in identifying a `light' Higgs boson at the LHC, provided that the forward outgoing protons are tagged. We predict the cross sections for the signal and for all possible bbbar backgrounds.
In the present paper, we present detailed discussions on the hadronic production of $Ξ_{cc}$ at a fixed target experiment at the LHC (After@LHC). The charm quarks in hadron could be either extrinsic or intrinsic. By using the BHPS model as the intrinsic charm distribution function in proton, we observe that even if by setting the proportion of finding the intrinsic charm in a proton as $A_{\rm in}=1\%$, total cross sections for the $g+c$ and $c+c$ production mechanisms shall be enhanced by nearly two times. Thus the number of $Ξ_{cc}$ events to be generated at the After@LHC can be greatly enha…
We show that crystal can trap a broad (x, x', y, y', E) distribution of particles and channel it preserved with a high precision. This sampled-and-hold distribution can be steered by a bent crystal for analysis downstream. In simulations for the 7 TeV Large Hadron Collider, a crystal adapted to the accelerator lattice traps 90% of diffractively scattered protons emerging from the interaction point with a divergence 100 times the critical angle. We set the criterion for crystal adaptation improving efficiency ~100-fold. Proton angles are preserved in crystal transmission with accuracy down to 0…
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