The LHC program will include the identification of events with single prompt high-k_\perp 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. At the parton level, we analyze single photon production in gluon fusion, gg \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 completely determined by the mixing parameter (which is actually determined in the minimal theory) -- and it is otherwise model-(compactification-) independent. We discuss the string signal cross sections as well as the QCD background. The present analysis takes into account the recently obtained decay widths of first Regge recurrences, which are necessary for more precise determination of these cross sections in the resonant region. A vital part of the background discussion concerns the minimization of misidentified π^0's emerging from high-p_\perp jets. We show that even for relatively small mixing, 100 fb^-1 of LHC data could probe deviations from standard model physics associated with TeV-scale strings at a 5σsignificance, for M_{\rm string} as large as 2.3 TeV. It is also likely that resonant bumps could be observed with approximately the same signal-to-noise ratio.
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.
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…
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 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 …
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…
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.
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…
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…
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.
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 …
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…
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,…
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…
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…
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.
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.
The mass scale of fundamental strings can be as low as few TeV/c^2 provided that spacetime extends into large extra dimensions. We discuss the phenomenological aspects of weakly coupled low mass string theory related to experimental searches for physics beyond the Standard Model at the Large Hadron Collider (LHC). We consider the 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. We focus on the model-independent, universal features …
We survey the low-energy supersymmetry phenomenology of a three-family Pati-Salam model constructed from intersecting D6-branes in Type IIA string theory on the T^6/(Z_2 x Z_2) orientifold which possesses many of the phenomenological properties desired in string model-building. In the model, there is no exotic matter in the low-energy spectrum, the correct mass hierarchies for quarks and leptons may be obtained, and the gauge couplings are automatically unified at the string scale. We calculate the supersymmetry breaking soft terms and the corresponding low-energy supersymmetry particle spectr…
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…
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.
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…
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…
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 …
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.
Axion-like particles (ALPs) are predicted by many extensions of the Standard Model (SM). When ALP mass lies in the range of MeV to GeV, the cosmology and astrophysics will be largely irrelevant. In this work, we investigate such light ALPs through the ALP-strahlung process $pp \to V a (\to γγ)$ at the 14 TeV LHC with an integrated luminosity of 3000 fb$^{-1}$ (HL-LHC). With the photon-jet algorithm, we demonstrate that our approach can probe the mass range of ALPs, which is inaccessible to previous LHC experiments. The obtained result can surpass the existing limits on ALP-photon coupling in t…
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 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…
Warped string compactifications, characterized by non-singular behavior of the metric in the infrared (IR), feature departures from the usual anti-de Sitter warped extra dimensions. We study the implications of the smooth IR cutoff for Randall-Sundrum (RS) type models. We find that the phenomenology of the KK gravitons (including their masses and couplings) depends sensitively on the precise shape of the warp factor in the IR. In particular, we analyze the warped deformed conifold and find that the spectrum differs significantly from that of RS, and present a simple prescription (a mass gap an…
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.
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 investigate the reach at the LHC to probe light sterile neutrinos with displaced vertices. We focus on sterile neutrinos $N$ with masses $m_{N} \sim $ (5-30) GeV, that are produced in rare decays of the Standard Model gauge bosons and decay inside the inner trackers of the LHC detectors. With a strategy that triggers on the prompt lepton accompanying the $N$ displaced vertex and considers charged tracks associated to it, we show that the 13 TeV LHC with $3000$/fb is able to probe active-sterile neutrino mixings down to $|V_{lN}|^2\approx 10^{-9}$, with $l=e,μ$, which is an improvement of up…
We propose to utilize the transverse mass variable $M_{T2}$ and it's descendant $M_{2Cons}$ for constraining the CP admixture of the tau lepton Yukawa coupling at the LHC. We have considered the tau lepton pair produced from the Higgs boson with each tau decays to a charged pion and a neutrino, $τ^{\pm} \rightarrow π^{\pm} ν_τ$. Recently, for this channel, the LHC has employed the impact parameter method to measure the CP mixing angle of tau lepton Yukawa coupling with large uncertainty. The observables we propose here can be measured in the lab frame without the impact parameter measurement a…
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 LHC possibilities to constrain the parameters of the Randall-Sundrum-like model with one warped extra dimension and small curvature through the diphoton production in the photon-induced process pp -> p gamma gamma p -> p' gamma gamma p' are investigated. Two acceptances of the forward detectors, 0.015 < xi < 0.15 and 0.015 < xi < 0.5, where xi is the fractional proton momentum loss of the incident protons, are considered. The sensitivity bounds on the 5-dimensional gravity scale are obtained as a function of the LHC integrated luminosity.
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…
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…
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 …
Recent work has shown that compactifications of F-theory provide a potentially attractive phenomenological scenario. The low energy characteristics of F-theory GUTs consist of a deformation away from a minimal gauge mediation scenario with a high messenger scale. The soft scalar masses of the theory are all shifted by a stringy effect which survives to low energies. This effect can range from 0 GeV up to ~ 500 GeV. In this paper we study potential collider signatures of F-theory GUTs, focussing in particular on ways to distinguish this class of models from other theories with an MSSM spectrum.…
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 …
The question if the Bose statistics is broken at the TeV scale is discussed. The decay of a new heavy spin 1 gauge boson Z' into two photons, Z'-> 2 gamma, is forbidden by the Bose statistics among other general principles of quantum field theory (Landau-Yang theorem). We point out that the search for this decay can be effectively used to probe the Bose symmetry violation at the CERN LHC.
If the fundamental planck scale is near a TeV, then parton collisions with high enough center-of-mass energy should produce black holes. The production rate for such black holes at LHC has been extensively studied for the case of a proton-proton collision. In this paper, we extend this analysis to a lead-lead collision at LHC. We find that the cross section for small black holes which may in principle be produced in such a collision is either enhanced or suppressed, depending upon the black hole mass. For example, for black holes with a mass around 3 TeV we find that the differential black hol…
We investigate the sensitivity of the Large Hadron Collider to supersymmetric setups using monotop probes in which the signal is a single top quark produced in association with missing transverse energy. Our prospective study relies on Monte Carlo simulations of 300 invfb of proton- proton collisions at a centre-of-mass energy of 14 TeV and considers both leptonic and hadronic monotop decays. We present analysis strategies sensitive to regions of the supersymmetric parameter space which feature small superparticle mass splittings and illustrate their strengths in the context of a particular se…
Models incorporating flavoured dark matter provide an elegant solution to the dark matter problem, evading the tight LHC and direct direction constraints on simple WIMP models. In Dark Minimal Flavour Violation, a simple framework of flavoured dark matter with new sources of flavour violation, the constraints from thermal freeze-out, direct detection experiments, and flavour physics create well-defined benchmark scenarios for these models. We study the LHC phenomenology of four such scenarios, focusing on final states where a single top quark is produced accompanied by no jets, one jet from th…
In the context of the Standard Model effective field theory (SMEFT) we examine the constraints on the trilinear Higgs coupling that originate from off-shell Higgs production in proton-proton collisions. Our calculation of the $gg \to h^\ast \to Z Z \to 4 \ell$ process includes two-loop corrections to gluon-gluon-fusion Higgs production and one-loop corrections to the Higgs propagator and its decay. Employing a matrix-element based kinematic discriminant we determine the reach of LHC Run 3 and the high-luminosity option of the LHC in constraining the relevant SMEFT Wilson coefficients. We prese…
A general prediction of string unification is the existence of exotic states with fractional charges under the free unbroken Abelian generators of the underlying GUT symmetry. Such states may be long-lived due to the existence of weakly broken gauge, or local discrete, symmetries, and may serve as experimental probes of string theory in forthcoming cosmic ray and dark matter experiments.
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 ~ …
Vector boson fusion (VBF) processes offer a promising avenue to study the non-colored sectors of supersymmetric extensions of the Standard Model at the LHC. A feasibility study for searching for the chargino/neutralino system in the $R-$parity conserving Minimal Supersymmetric Standard Model is presented. The high $E_T$ forward jets in opposite hemispheres are utilized to trigger VBF events, so that the production of the lightest chargino and the second lightest neutralino can be probed without a bias by experimental triggers. Kinematic requirements are developed to search for signals of these…
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…
We propose a LHC search for dilepton resonances in association with large missing energy as a generic probe of TeV dark sector models. Such resonances can occur if the dark sector includes a U(1) gauge boson, or Z', which kinetically mixes with the Standard Model U(1). For small mixing, direct 2 to 1 production of the Z' is not visible in standard resonance searches due to the large Drell-Yan background. However, there may be significant production of the Z' boson in processes involving other dark sector particles, resulting in final states with a Z' resonance and missing transverse momentum. …
