Luis A. Anchordoqui
The LHC program will include the identification of events with single high-k_T photons as probes of new physics. We show that this channel is uniquely suited to search for experimental evidence of TeV-scale open string theory.
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With the advent of the LHC and the continuing influx of cosmological data, phenomenological aspects of string theory have received renewed attention in recent years and many problems have been properly incorporated in this framework. In this Dissertation, we suggest new string-related candidates for the origin of dark energy and dark matter and propose ways of searching for string resonances at the LHC.
Soft multiparticle production processes in hadronic collisions are considered in the framework of the Quark-Gluon Strings Model and the model predictions are compared with data from SppS and Tevatron. Predictions for LHC energies are given.
We have examined the dijet production at the LHC as a hint to discovery of string Regge excitations of Standard Model particles. If the fundamental string mass scale is in the TeV range, the influence of string effects on the $pp$ interaction can arise as new resonances in the dijet invariant mass distribution. Near the first resonant pole we investigate the impact of the subprocesses with quark-gluon and four-gluon separately. We show that the LHC is able to probe the string mass scale $\sim$5 TeV with only 2 pb$^{-1}$ of integrated luminosity at $E_{CM}=14$ TeV.
A new shooting string holographic model of jet quenching of light quarks in strongly coupled plasmas is presented to overcome the phenomenological incompatibilities of previous falling string holographic scenarios that emerged when confronted with the recent LHC data. This model is based on strings with finite momentum endpoints that start close to the horizon and lose energy as they approach the boundary. This framework is applied to compute the nuclear modification factor RAA of light hadrons at RHIC and LHC, showing that this model improves greatly the comparison with the recent light hadro…
We consider extensions of the standard model based on open strings ending on D-branes, with gauge bosons due to strings attached to stacks of D-branes and chiral matter due to strings stretching between intersecting D-branes. Assuming that the fundamental string mass scale is in the TeV range and the theory is weakly coupled, we review possible signals of string physics at the Large Hadron Collider.
We study the enhancement of $c \bar c$ pair production that takes place in central heavy ion collisions due to the formation of clusters of strings. These clusters produce heavy flavors more efficiently due to their higher color. We discuss the competition between this mechanism and the well-known screening of color charge, which, above a critical string density, reduces strongly the probability of binding these $c \bar c$ pairs to form $J/Ψ$ particles. The dependence of $J/Ψ$ suppression on the centrality shows a peak at both RHIC and LHC energies corresponding to the percolation critical den…
The dependence of the multiplicity and the transverse momentum distribution on the number of collisions are studied for central and peripheral Au-Au collisions at SPS, RHIC and LHC energies in the framework of percolation of strings. A scaling law relating the multiplicity to the mean transverse momentum is obtained. Our results are in overall agreement with the SPS and RHIC data, obtaining a suppression on $p_T$ distribution even for $p_T$ larger than 1 GeV/c.
The percolation of strings gives a good description of the RHIC experimental data on the elliptic flow, v2 and predicted a rise on the integrated v2 of the order of 25% at LHC such as it has been experimentally obtained. We show that the dependence of v2 on pT for RHIC and LHC energies is approximately the same as it has been observed, for all the centralities. We show the results for different particles and the dependence of v2 on the centralities and rapidity. Our results are compatible with an small value of the ratio eta/s in the whole energy range such as it was expected in the percolatio…
If extra dimensions are found in the second run of LHC in the $pp$ collisions at $\sqrt{s}$ = 14 TeV then the string scale can be $\sim$ TeV, and we should produce string balls at LHC. In this paper we study supersymmetry (squark and gluino) production from string balls at LHC in $pp$ collisions at $\sqrt{s}$ = 14 TeV and compare that with the parton fusion results using pQCD. We find significant squark and gluino production from string balls at LHC which is comparable to parton fusion pQCD results. Hence, in the absence of black hole production at LHC, an enhancement in supersymmetry producti…
We consider the phenomenological implications of the assumption that baryons are systems of three quarks connected through gluon string junction. The transfer of baryon number in rapidity space due to the string junction propagation is considered in detail. At high energies this process leads to a significant effect on the net baryon production in hN collisions at mid-rapidities. The numerical results for midrapidity inclusive densities of different secondaries in the framework of the Quark-Gluon String Model are in reasonable agreement with the experimental data. One universal value lambda ~ …
We demonstrate that some of the suggested five supergravity points for study at the LHC could be approximately derived from perturbative string theories or M-theory, but that charge and colour breaking minima would result. As a pilot study, we then analyse a perturbative string model with non-universal soft masses that are optimised in order to avoid global charge and colour breaking minima. By combining measurements of up to six kinematic edges from squark decay chains with data from a new kinematic variable, designed to improve slepton mass measurements, we demonstrate that a typical LHC exp…
Strangeness and baryon enhancement in heavy ion collisions are discussed in the framework of the String Fusion Model. The Monte Carlo version of this model is shown to reasonably reproduce three of the features that have been pointed out as evidences of the finding of the Quark Gluon Plasma. Namely hyperon/antihyperon enhancement, dependence of the slope of the $p_{T}$ distributions on the mass of the produced particles and on the centrality of the collision, are described. Predictions for RHIC and LHC energies are presented.
We explain what features of string theory can be tested at the LHC. We review the present bounds on the string mass and on extra gauge bosons as well as the prospects for the upcoming experiments.
If we find extra dimensions in the second run of the LHC in the $pp$ collisions at $\sqrt{s}$ = 14 TeV, then the string mass scale $M_s$ can be $\sim$ TeV and we should produce QCD jets in $2 \rightarrow 2$ partonic collisions via string Regge excitations at the LHC. QCD jets can also be produced from string balls via thermal radiation at Hagedorn temperature. In this paper we study jet production from string Regge excitations vs string balls in $pp$ collisions at $\sqrt{s}$ = 14 TeV at LHC and make a comparison with the standard model QCD jets. We find that high $p_T$ jet production from stri…
We continue the study of a class of string-motivated effective supergravity theories in light of current data from the CERN Large Hadron Collider (LHC). In this installment we consider Type IIB string theory compactified on a Calabi-Yau orientifold in the presence of fluxes, in the manner originally formulated by Kachru, et al. We allow for a variety of potential uplift mechanisms and embeddings of the Standard Model field content into D3 and D7 brane configurations. We find that an uplift sector independent of the Kahler moduli, as is the case with anti-D3 branes, is inconsistent with data un…
Multiplicity correlations in the model with string clusters in pp collisions at LHC energies
本研究在弦团模型框架下探究LHC能区质子-质子碰撞的快度多重数关联，通过蒙特卡洛模拟结合碰撞参数晶格计入弦融合效应，验证模型可重现关联系数随能量、快度间距及窗口宽度的变化特征。
The multiple production processes of secondary hadrons in proton-antiproton scattering are divided into three types. The first type is a shower of secondary hadrons produced from gluon string decay, the second type is a shower of secondary hadrons produced from two quark strings decay and the third is a shower produced from three quark strings decay. At the same time there are only two types for proton-proton scattering - shower from gluon string and shower from two quark strings. These showers do not correspond to pomeron showers originating from cuts of one, two, three, ... pomerons. Multipl…
Low-scale string models are phenomenological models in String Theory, in which the string scale M_s is of the order of TeV. String excited states which are characteristic modes in low-scale string models can be observed as resonances in dijet invariant mass distributions at the LHC. If a new heavy resonance is discovered at the LHC, it is important to investigate whether the resonance comes from low-scale string models. In this work, two analyses are performed: One is observing higher spin degeneracy of string excited states by an angular distribution analysis on the resonance, since the strin…
The experimental data on p, Lambda, Xi-, Omega-, baryons and the corresponding antibaryons spectra obtained by different collaborations are compared with the results of the calculations performed into the frame of the Quark-Gluon String Model. The contribution of String Junction diffusion and the inelastic screening corrections are accounted for in the theoretical calculations. The predictions of the Quark-Gluon String Model both for pp and pA collisions are extended up to the LHC energies.
In string theory, black holes have a minimum mass below which they transition into highly excited long and jagged strings --- ``string balls''. These are the stringy progenitors of black holes; because they are lighter, in theories of TeV-gravity, they may be more accessible to the LHC or the VLHC. They share some of the characteristics of black holes, such as large production cross sections. Furthermore, they evaporate thermally at the Hagedorn temperature and give rise to high-multiplicity events containing hard primary photons and charged leptons, which have negligible standard-model backgr…
We study models with heavy exotics that account for the LHC $750$ GeV diphoton excess in light of current vector-like quark bounds. Utilizing only exotics that may appear in three-stack and four-stack D-brane models, we show that a narrow width diphoton excess can be accounted for while evading existing bounds if multiple exotics are added, with vector-like leptons of mass $M_L\lesssim 375$ GeV and vector-like quarks with masses up to $\simeq 3$ TeV. However, a large width $(Γ/M \sim 0.06)$, as suggested by the ATLAS data, cannot be easily accommodated in this framework. Renormalization group …
The first string excited state can be observed as a resonance in dijet invariant mass distributions at the LHC, if the scenario of low-scale string with large extra dimensions is realized. A distinguished property of the dijet resonance by string excited states from that the other "new physics" is that many almost degenerate states with various spin compose a single resonance structure. It is examined that how we can obtain evidences of low-scale string models through the analysis of angular distributions of dijet events at the LHC. Some string resonance states of color singlet can obtain larg…
According to string theory, string ball is a highly excited long string which decays to standard model particles at the Hagedorn temperature with thermal spectrum. If there are extra dimensions, the string scale can be $\sim$ TeV, and we should produce string balls at CERN LHC. In this paper we study top quark production from string balls at LHC and compare with the parton fusion results at NNLO using pQCD. We find significant top quark production from string balls at LHC which is comparable to standard model pQCD results. We also find that $\frac{dσ}{dp_T}$ of top quarks from string balls doe…
The results of string percolation on multiplicities and elliptic flow in AA and pp collisions are compared with LHC data showing a good agreement. We discuss the rapidity long range correlations and its relation to the height and longitudinal extension of the ridge structure. Finally we show that the dependence of the shear viscosity over entropy density ratio on the temperature, presents a minimum close to the critical temperature remaining small in the range of the RHIC and LHC energies.
We consider $Z'$s in heterotic string derived models and study $Z'$ resonant production at the TeV scale at the Large Hadron Collider (LHC). We use various kinematic differential distributions for the Drell-Yan process at NNLO in QCD to explore the parameter space of such models and investigate $Z'$ couplings. In particular, we study the impact of $Z$-$Z'$ kinetic-mixing interactions on forward-backward asymmetry ($A_{FB}$) and other distributions at the LHC.
We construct LHC signature footprints for four semi-realistic string/$M$ theory vacua with an MSSM visible sector. We find that they all give rise to limited regions in LHC signature space, and are qualitatively different from each other for understandable reasons. We also propose a technique in which correlations of LHC signatures can be effectively used to distinguish among these string theory vacua. We expect the technique to be useful for more general string vacua. We argue that further systematic analysis with this approach will allow LHC data to disfavor or exclude major ``corners'' of s…
I show a brief historical overview of recent developments on the black hole physics that can be possibly explored at LHC. I comment on the correspondence principle of black holes and strings and show its realization in a differential production cross section of a black hole/string ball with fixed angular momentum.
We study Higgs production and decay from TeV scale string balls in $pp$ collisions at $\sqrt{s}$ = 14 TeV at LHC. We present the results of total cross section of diphotons, invariant mass distribution of the diphotons and $p_T$ distribution of the diphotons and $ZZ$ pairs from Higgs from string balls at LHC. We find that the invariant mass distribution of diphotons from Higgs from string balls is not very sensitive to the increase in diphoton invariant mass. We find that for string mass scale $M_s$=2.5 TeV, which is the lower limit of the string mass scale set by the recent CMS collaboration …
Prospects for supersymmetry at high luminosity LHC
本文综述LHC与WIMP暗物质限制对多种SUSY模型的影响，并基于弦景观和人择约束论证HL-LHC仍有望在非普适希格斯质量等自然SUSY参数区发现超对称。
The mass scale M_s of superstring theory is an arbitrary parameter that can be as low as few TeVs if the Universe contains large extra dimensions. We propose a search for the effects of Regge excitations of fundamental strings at LHC, in the process p p \to γjet. The underlying parton process is dominantly the single photon production in gluon fusion, g g \to γg, with open string states propagating in intermediate channels. If the photon mixes with the gauge boson of the baryon number, which is a common feature of D-brane quivers, the amplitude appears already at the string disk level. It is c…
The properties of the strongly intensive variable characterizing correlations between the number of particles in two separated rapidity interval in pp interactions at LHC energies are studied in the framework of the string fusion model. We perform the MC simulations of string distributions in the impact parameter plane to take into account the experimental conditions of pp collisions. We account the string fusion processes, leading to the formation of string clusters, embedding a finite lattice (a grid) in the impact parameter plane. As a result, we found the dependence of this variable both o…
We derive a new formula for jet energy loss using finite endpoint momentum shooting strings initial conditions in SYM plasmas to overcome the difficulties of previous falling string holographic scenarios. We apply the new formula to compute the nuclear modification factor RAA and the elliptic flow parameter v2 of light hadrons at RHIC and LHC. We show furthermore that Gauss-Bonnet quadratic curvature corrections to the AdS5 geometry improve the agreement with the recent data.
We explore phenomenological signatures of light quark jet quenching within the AdS/CFT correspondence. Numerical studies of the instantaneous energy loss of light quarks, modeled as falling strings, suggest a linear path dependence. We propose a phenomenological model for the energy loss and use it to compute the nuclear modification factor $R_{AA}$ for light quarks in an expanding plasma with Glauber initial conditions. The results are compared to the light hadron $R_{AA}$ data at the LHC and, although they show qualitative agreement, the quantitative disagreement we found motivated the explo…
We argue that it is possible to address the deeper LHC Inverse Problem, to gain insight into the underlying theory from LHC signatures of new physics. We propose a technique which may allow us to distinguish among, and favor or disfavor, various classes of underlying theoretical constructions using (assumed) new physics signals at the LHC. We think that this can be done with limited data $(5-10 fb^{-1})$, and improved with more data. This is because of two reasons -- a) it is possible in many cases to reliably go from (semi)realistic microscopic string construction to the space of experimental…
The recently reported effect of long-range near-side angular correlations at LHC occurs for large multiplicities of particles with $1\,GeV\,<p_T\,<\,3\,GeV$. To understand the effect several possibilities have been discussed. In the letter we propose a simple qualitative mechanism which corresponds to gluon bremstralung of quarks moving with acceleration appropriate to the quark--anti-quark string. The smallness of azimuthal angle difference $Δϕ$ along with large $Δη$ at large multiplicities in this interval of $p_T$ are natural in the mechanism. The mechanism predicts also bremstralung photon…
The string theory landscape of vacua solutions provides physicists with some understanding as to the magnitude of the cosmological constant. Similar reasoning can be applied to the magnitude of the soft SUSY breaking terms in supersymmetric models of particle physics: there appears to be a statistical draw towards large soft terms which is tempered by the anthropic requirement of the weak scale lying not too far from ~100 GeV. For a mild statistical draw of m_{soft}^n with n=1 (as expected from SUSY breaking due to a single F term) then the light Higgs mass is preferred at ~125 GeV while spart…
I discuss some (unconventional) aspects of String Cosmology of relevance to supersymmetric dark matter searches at the Large Hadron Collider (LHC) at CERN. In particular, I analyse the role of time-dependent dilaton fields in relaxing some of the stringent constraints that characterise minimal supersymmetric models in standard cosmology. I also study briefly CPT-violating aspects of brane Universe models with space-time brane defects at early epochs and their potential relevance to the observed Baryon Asymmetry.
We study aspects of TeV string scale models of intersecting D-branes. The gauge bosons arise from strings ending on stacks of D-branes, whereas chiral matter arises from strings stretched between intersecting D-branes. Our focus is on scattering amplitudes (at tree-level), Regge states (string excitations), and collider phenomenology. Achieving a low string scale is possible in models of Large extra dimensions. At the LHC, a low enough string scale implies that cross sections will deviate from their standard model predictions. Moreover, Regge states as well as Kaluza-Klein states and winding s…
We consider extensions of the standard model based on open strings ending on D-branes, with gauge bosons due to strings attached to stacks of D-branes and chiral matter due to strings stretching between intersecting D-branes. Assuming that the fundamental string mass scale is in the TeV range and the theory is weakly coupled, we discuss possible signals of string physics at the Large Hadron Collider (LHC). In previous works, direct channel excitations of Regge recurrences in parton-parton scattering supplied the outstanding new signature. The present work considers the deviation from standard …
We consider extensions of the standard model based on open strings ending on D-branes, with gauge bosons due to strings attached to stacks of D-branes and chiral matter due to strings stretching between intersecting D-branes. Assuming that the fundamental string mass scale is in the TeV range and the theory is weakly coupled, we discuss possible signals of string physics at the Large Hadron Collider (LHC). In such D-brane constructions, the dominant contributions to full-fledged string amplitudes for all the common QCD parton subprocesses leading to dijets are completely independent of the det…
In this article, we show that making global fits of string theory model parameters to data is an interesting mechanism for probing, mapping and forecasting connections of the theory to real world physics. We considered a large volume scenario (LVS) with D3-branes matter fields and supersymmetry breaking. A global fit of the parameters to low energy data shows that the set of LVS models are associated with light gluinos which are quasi-degenerate with the neutralinos and charginos they can promptly decay into and thus possibly hidden to current LHC gluino search strategies.
Effective operators provide a model-independent description of physics beyond the stan- dard model that is particularly useful given the absence of any signs of new physics at the Large Hadron Collider (LHC). We recast previous LHC analyses to set limits on lepton-flavour-violating gluonic effective operators of dimension 8 and compare our results to existing limits from low-energy precision experiments. Current LHC data constrains the scale $Λ$ of the effective operators to be larger than $Λ\gtrsim 0.5 - 1.6$ TeV depending on the flavour and thus provides the most stringent limit for all oper…
Soft pp interactions are considered in the framework of the phenomenological model with color strings formation. Under the assumption, that the elementary collision is realized as interaction of two color dipoles, the total inelastic cross section and the multiplicity of the charged particles are estimated and used for the parameters fixing. The special attention is given to the modelling of exclusive parton distributions taking into account the energy conservation and fixing the mass center that is necessary for the description of correlations, corresponding Monte Carlo procedures are develop…
The di-photon excess observed at the LHC can be explained as a Standard Model singlet that is produced and decays by heavy vector-like colour triplets and electroweak doublets in one-loop diagrams. The characteristics of the required spectrum are well motivated in heterotic-string constructions that allow for a light $Z^\prime$. Anomaly cancellation of the $U(1)_{Z^\prime}$ symmetry requires the existence of the Standard Model singlet and vector-like states in the vicinity of the $U(1)_{Z^\prime}$ breaking scale. In this paper we show that the agreement with the gauge coupling data at one-loop…
We investigate the production, signatures and backgrounds of new heavy leptons via string inspired $E_{6}$ model at the proposed Linac$\otimes$LHC. Assuming maximal mixing, the production rate is found to be 2000 events per year for masses up to 3 TeV.
We begin the study of a class of string-motivated effective supergravity theories in light of current data from the CERN Large Hadron Collider (LHC). The case of heterotic string theory, in which the dilaton is stabilized via non-perturbative corrections to the Kahler metric, will be considered first. This model is highly constrained and therefore predictive. We find that much of the reasonable parameter space afforded to the model -- representing the strong dynamics of a presumed gaugino condensation in the hidden sector -- is now observationally disfavored by the LHC results. Most of the the…
We extend the study of scattering amplitudes presented in ``The LHC String Hunter's Companion'' to the case of five-point processes that may reveal the signals of low mass strings at the LHC and are potentially useful for detailed investigations of fundamental Regge excitations. In particular, we compute the full-fledged string disk amplitudes describing all 2->3 parton scattering subprocesses leading to the production of three hadronic jets. We cast our results in a form suitable for the implementation of stringy partonic cross sections in the LHC data analysis. We discuss the universal, mode…
We consider black hole production at the LHC in a generic scenario with many extra dimensions where the Standard Model fields are confined to a brane. With $\sim 20$ dimensions the hierarchy problem is shown to be naturally solved without the need for large compactification radii. We find that in such a scenario the properties of black holes can be used to determine the number of extra dimensions, $n$. In particular, we demonstrate that measurements of the decay distributions of such black holes at the LHC can determine if $n$ is significantly larger than 6 or 7 with high confidence, and thus …
A Monte Carlo model to simulate nuclear collisions in the energy range going from SPS to LHC, is presented. The model includes in its initial stage both soft and semihard components, which lead to the formation of color strings. Collectivity is taken into account considering the possibility of strings in color representations higher than triplet or antitriplet, by means of string fusion. String breaking leads to the production of secondaries. At this point, the model can be used as initial condition for further evolution by a transport model. In order to tune the parameters and see the results…
String theories with topologically complex compactification manifolds suggest the simultaneous presence of many unbroken U(1)'s without any light matter charged under them. The gauge bosons associated with these U(1)'s do not have direct observational consequences. However, in the presence of low energy supersymmetry the gauge fermions associated with these U(1)'s, the "photini", mix with the Bino and extend the MSSM neutralino sector. This leads to novel signatures at the LHC. The lightest ordinary supersymmetric particle (LOSP) can decay to any one of these photini. In turn, photini may tran…
The ATLAS and CMS collaborations recently recorded possible di-photon excess at 750 GeV and a less significant di-boson excess around 1.9 TeV. Such excesses may be produced in heterotic-string derived Z' models, where the di-photon excess may be connected with the Standard Model singlet scalar responsible for the Z' symmetry breaking, whereas the di-boson excess arises from production of the extra vector boson. Additional vector-like states in the string Z' model are instrumental to explain the relatively large width of the di-photon events and mandated by anomaly cancellation to be in the vic…
The asymmetry of baryon/antibaryon production has been measured in many proton-proton, pion-proton and electron-proton experiments. In the framework of Quark-Gluon String Model (QGSM) the energy dependence of asymmetry tells us about the value of $α_{SJ}$(0), the intercept of String Junction Regge trajectory. In previous QGSM study, the value of intercept has been estimated as 0.5 < $α_{SJ}$(0) < 0.9. Here, SJ behaviors are accumulated in the model based on topological expansion in order to build a neutral object with zero baryon charge. By the way, QCD mass falling under the event horizon of …
Low-scale string models, in which the string scale M_s is of the order of TeV with large extra dimensions, can solve the problems of scale hierarchy and non-renormalizable quantum gravity in the standard model. String excited states of the standard model particles are possibly observed as resonances in the dijet invariant mass distribution at the LHC. There are two properties to distinguish whether the resonances are due to low-scale string or some other "new physics". One is a characteristic angular distribution in dijet events at the resonance due to spin degeneracy of string excited states,…
We analyze high multiplicity proton-proton ($pp$) collision data in the framework of the String Percolation Model (SPM) that has been successful in describing several phenomena of multiparticle production, including the signatures of recent discovery of strongly interacting partonic matter, the Quark Gluon Plasma (QGP), in relativistic heavy-ion collisions. Our study in terms of the ratio of shear viscosity and entropy density ($η/s$) and the (LQCD) predicted signature of QCD change of phase, in terms of effective number of degrees of freedom ($ε/T^4$), reiterates the possibility of strongly i…
The strongly intense quantities and robust variances in processes of multi-particle production in pp and AA interactions at LHC energies was studied. The Monte Carlo and analytic modelling of these quantities in the framework of a quark-gluon string model were implies. The string fusion effects were also taken into account by implementing of a lattice (grid) in the impact parameter plane. Strongly intensive variable $Σ(n_F,\ n_B)$ was calculated for different energies for two values of the width of the observation rapidity windows as a function of the distance between the centres of this windo…
In TeV-scale gravity scenarios with large extra dimensions, black holes may be produced at future colliders. Good arguments have been made for why general relativistic black holes may be just out of reach of the Large Hadron Collider (LHC). However, in weakly-coupled string theory, highly excited string states - string balls - could be produced at the LHC with high rates and decay thermally, not unlike general relativistic black holes. In this paper, we simulate and study string ball production and decay at the LHC. We specifically emphasize the experimentally-detectable similarities and diffe…
We present a systematic study on the strange particle production at the Large Hadron Collider (LHC) in proton-proton (pp) collisions at $\sqrt{s}=$ 7 TeV based on PACIAE simulations. Two different mechanisms accounting for single string structure variations and multiple string interactions are implemented in the simulations. These modifications give rise to increased effective string tension in the Lund fragmentation model and generate more strange particles in the hadronic final state. By comparing the results with a wealth of the LHC data, it is turned out that the inclusion of variable effe…
In string realizations of the Randall-Sundrum scenario, the higher-spin Regge excitations of Standard Model states localized near the IR brane are warped down to close to the TeV scale. We argue that, as a consequence of the localization properties of Randall-Sundrum models of flavour, the lightest such resonance is the spin-3/2 excitation of the right-handed top quark over a significant region of parameter space. A mild accidental cancellation allows this resonance to be as light or lighter than the Kaluza-Klein excitations of the Standard Model states. We consider from a bottom-up effective …
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.
The Quark Gluon String Model (QGSM) reproduces well the global characteristics of the $pp$ collisions at RHIC and LHC, e.g., the pseudorapidity and transverse momenta distributions at different centralities. The main goal of this work is to employ the Monte Carlo QGSM for description of femtoscopic characteristics in $pp$ collisions at RHIC and LHC. The study is concentrated on the low multiplicity and multiplicity averaged events, where no collective effects are expected. The different procedures for fitting the one-dimensional correlation functions of pions are studied and compared with the …
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