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The program of the Conference will address a broad range of topics covering the main areas of high-energy particle and nuclear physics. Our scientific program will include: Higgs Physics, Hadron Spectroscopy, Neutrino Physics, Hadron Structure, High-Energy QCD, Non-perturbative QCD, Heavy Ion collisions, Particle Detectors and Instrumentation, Beyond the SM Physics, Dark Matter searches, Phenomenology of AdS/CFT, Astroparticles, Future experiments, and other topics.
The aim of the Conference is to bring together young and senior scientists, theorists and experimentalists, to review the recent progress in high energy particle and nuclear physics. We strongly encourage presentations of physics results from experimental facilities (LHC, FermiLab, RHIC, JLab, DESY, etc), future experimental facilities (LHeC, FCC-ee, EIC, CTA, etc) and theoreticians to participate in the event.
Students and young postdocs are also encouraged to participate in the HEP School the week after the workshop on January 15-19.
Local Organizing Committee:
(UTFSM)
Registration Fee*:
300.000 CLP, 460 USD or 430 EUR
* The registration fee can be paid online (see Online Payment Entry in the menu) and can also be paid upon arrival (cash only).
TBD
Models with radiative neutrino masses and viable dark matter candidates usually have implications in all the frontiers of particle physics and astrophysics, like colliders signatures with (multi)leptons plus missing energy at the LHC, direct and indirect dark matter detection experiments, and neutrino oscillation experiments. In this talk I will review the status of the simplest models in the light of current and future experimental data.
The $\mu\tau$-reflection symmetry is a simple symmetry capable of predicting all the unknown CP phases of the lepton sector and the atmospheric angle but too simple to predict the absolute neutrino mass scale or the mass ordering.
We show that by combining it with a discrete abelian symmetry in a nontrivial way we can additionally enforce a texture-zero and obtain a highly predictive scenario where the lightest neutrino mass is fixed to be in the few meV range for two normal ordering (NO) solutions or in the tens of meV in one inverted ordering (IO) solution.
The rate for neutrinoless double beta decay is predicted to be negligible for NO or have effective mass $m_{\beta\beta}\approx 14\text{ -- }29\,{\rm meV}$ for IO, right in the region to be probed in future experiments.
We discuss the generation of neutrino masses from dimension seven 1-loop diagrams. We systematically analyse all possible d=7 1-loop topologies. There is a total of 48 topologies, but only 8 of them can lead to "genuine" d=7 neutrino masses. Here, we define genuine models to be models in which neither d=5 nor d=7 tree level masses nor a d=5 1-loop mass appear, such that d=7 loop is the leading order contribution to the neutrino masses. We organize these models according to their particle content. We find there is only one diagram with no representation larger than triplet while there are 22 diagrams with quadruplets. We discuss two minimal examples discussing possible future LNV searches at LHC consisting in leptons and gauge bosons with high multiplicity, such us 4l+4W, 6l+2w.
The Jiangmen Underground Neutrino Observatory (JUNO) is a multi-purpose underground experiment under construction in south China. With 20 ktons of liquid scintillator, it will be the largest detector of this type ever assembled. Its primary goals are the determination of the neutrino mass hierarchy, the precise measurement of neutrino oscillation parameters, and the investigation of other rare processes, which include but are not limited to solar neutrinos, geo-neutrinos, supernova neutrinos and the diffuse supernova neutrinos background. An overview and current status of the experiment will be presented in this talk.
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The √s=100 TeV proton-proton collider (FCC-hh) is a core part of the Future Circular Collider project. The conceptual design of a suitable detector for FCC-hh is an integral part of this ongoing effort.
Such a detector should be able to operate under luminosities of up to 3x10^35 cm-2s-1, and pile-up conditions of up to ~1000 events per bunch crossing. In addition, the physics program includes signatures with highly boosted objects that create jets with very high track density and displaced secondary vertices far away from the interaction point. These conditions make particle tracking, vertex identification, and flavor tagging extremely challenging.
This talk presents a review of the general ideas and requirements that drive the current tracker and vertex detector design for FCC-hh, like detector granularity, material budget and pattern recognition. A special emphasis will be put on the reconstruction of boosted objects and the capability to identify heavy flavor jets.
The luminosity is a key parameter of each collider. Its precise and fast
measurement is essential for the physics program. The FCAL collaboration develops the technologies of compact and fast calorimeters with low average power consumption to measure the luminosity both with high precision using small angle Bhabha scattering and bunch-by-bunch using beamstrahlung pairs. For the precision device, called LumiCal, sensors are made of silicon, and for the fast device, called BeamCal, several options of radiation hard and very fast sensors, like GaAs or single crystal sapphire, are considered. A small Moliere radius facilitates
the measurement of Bhabha events in the presence of background and allows the detection of single high energy electrons on top of the widely spread background of beamstrahlung. Beside the luminosity measurement, the capability of detecting high energy electrons at low angles is important for many search experiments.
Two multi-plane prototypes of a luminometer were studied in beams of electrons and muons with momenta around 5 GeV at CERN and DESY. The results for the longitudinal and the transverse shower profiles are compared with Geant4 simulations of the setup and used to determine the effective Moliere radius of the prototypes. Recently developed ultra-thin detector planes demonstrate a very small effective Moliere radius approaching the technological limit. Dedicated multi-channel ultra-low power readout ASIC are under development in 130nm CMOS, comprising an analogue front-end and fast 10-bit ADC in each channel, followed by fast serialization and data transmission. Laboratory tests with prototypes confirmed the basic functionalities and established excellent agreement with simulations. In addition, an ASIC with a dual readout scheme for BeamCal allowing for a fast feedback to the accelerator and simultaneously data taking and calibration is under development.
The talk will give a summary of results about design optimisation, beam-tests and the status of the readout ASICs.
Precision timing detectors have the potential to transform event reconstruction in high energy physics experiments, especially at the LHC where pileup will significantly deteriorate the physics performance. I will be presenting current studies on particle identification at the LHC with enhanced detectors capable of delivering approximately 30 ps time resolution for minimum ionizing particles (MIPs). I will cover the sensor technologies being considered for these timing detectors, their performance in beam test experiments, and the current upgrade proposals for different experiments.
We show how collectivity arises from a simple model of proton-nucleus collisions. The model consists of a projectile comprised of nearly collinear quarks coherently scattering off localized domains of color charge of a dense nuclear target.
We find that many of the features observed in light-heavy ion collisions at RHIC and the LHC often ascribed to collectivity are qualitatively reproduced. These include the ordering of the azimuthal Fourier harmonics of two-particle correlations; a negative four-particle cumulant giving rise to a real $v_2\{4\}$; and the energy and transverse momentum dependence of $v_2\{4\}$. An abelian version of the model exhibits a scaling of the two, four, six, and eight particle correlations, $v2\{2\} > v2\{4\} \approx v2\{6\} \approx v2\{8\}$, often interpreted as a signature of collectivity.
The Lipatov's effective action for reggeized gluons, based on the gluodynamic Yang-Mills Lagrangian with external current for longitudinal gluons added, is considered. On the base of classical solutions the
one-loop corrections to this effective action in light-cone gauge are calculated. The Regge field theory (RFT) calculus for reggeized gluons, similar to the RFT introduced by Gribov, is proposed and discussed. The correctness of the results is verified by calculation of the propagator of reggeized gluons fields,the
application of the obtained results is discussed as well.
We use the effective action for reggeized gluons exploring ideas of \cite{LipatovEff}. Using light-cone gauge, we consider a problem with
only one longitudinal gluon field in the equations of motion included. With the two reggeon fields presented in the approach,
the first reggeon field is defined as a LO value of the corresponding gluon field, whereas the second reggeon field
arises as a source term in the Lagrangian. In this formulation
the effective action framework becomes similar to the light-cone Color Glass Condensate (CGC) approach.
The form of the effective
currents, arising in the equations of motion, therefore, can be obtained either directly from the effective action expression from \cite{LipatovEff} or
from the self-consistency conditions for the solution of the equations of motion, in both cases we obtain the same structure of the current.
The Lipatov effective action, see \cite{LipatovEff}, is a non-linear gauge invariant action which is assumed to be local in rapidity, that is,
all real and virtual particles in the direct channels split into groups in correspondence with their rapidities $y=\frac{1}{2} ln \Big( \frac{p_+}{p_-} \Big)$ and the
classical Lagrangian describes only interactions within one group whereas the interaction between groups with essentially different rapidities is realized by reggeon
exchange.
We have already obtained LO and NLO solutions, which are especially important for the construction of QCD based Regge Field Theory (RFT) calculus. These solutions were not considered in the CGC framework and
it can be important as some source of corrections in this framework. In the next paper we will present NNLO solutions,
that will be useful for calculations with the greater number of loops.
There are the following important applications: it can be used for the calculation of
production amplitudes in different scattering processes and calculation of sub-leading, unitarizing corrections to the
amplitudes and production vertices. The last task can be considered as a construction of the RFT based on the interaction of the fields of reggeized gluons, where different vertices of
the interactions are introduced and calculated.
We have calculated one-loop effective action for reggeized gluons using classical
solutions from \cite{Our1} and calculated a propagator for $A_{+}$ and $A_{-}$ reggeon fields in \cite{Our2}. This calculation can be considered as the check of the self-consistency of the approach and also as the explanation of the methods
of the calculation of
small-x BFKL based vertices in framework of the approach. There are other important vertices which can be similarly calculated.
These verices are important ingredients of the unitary corrections to different production and interaction amplitudes of the processes at high energies
and they will be considered in separate publications.
\begin{thebibliography}{99}
\bibitem{LipatovEff}
L.~N.~Lipatov,
Nucl. Phys. B {\bf 452}, 369 (1995); Phys. Rept. {\bf 286}, 131 (1997);
Subnucl. Ser. {\bf 49}, 131 (2013);
Int. J. Mod. Phys. Conf. Ser. {\bf 39}, 1560082 (2015);
Int. J. Mod. Phys. A {\bf 31}, no. 28/29, 1645011 (2016);
EPJ Web Conf. {\bf 125}, 01010 (2016).
\bibitem{Our1}
S.~Bondarenko, L.~Lipatov and A.~Prygarin,
Eur.\ Phys.\ J.\ C {\bf 77} (2017) no.8, 527.
\bibitem{Our2} S. Bondarenko, L. Lipatov, S. Pozdnyakov, A. Prygarin,
Eur.\ Phys.\ J.\ C {\bf 77} (2017) no.9, 630.
We investigate the spin-flip component of the Pomeron using the single spin asymmetry, $A_N(t)$, arising from Coulomb-nuclear interference (CNI) in small-angle elastic scattering.
The study of elastic proton-nucleus scattering is important because suppresses or excludes the contributions from iso-vector Reggeons which are predominantly spin-flip, and might have a significant impact on the results of fixed-target experiments at RHIC.
However, previous theoretical attempts fail to explain the recent data from the PHENIX experiment at RHIC on polarized proton-gold scattering, exposing a nontrivial $t$-dependence of $A_N$, strongly contradicting theoretical predictions. We found that the absorptive corrections in the Coulomb amplitude of $pA$ elastic scattering play a significant role. Namely, interference of ultra-peripheral and central collisions leads to a dramatic changes in $A_N(t)$.
We also include less significant corrections from Gribov inelastic shadowing and from $NN$ correlations.
Finally, we present that the non-zero hadron spin-flip amplitude is required to describe the single spin asymmetry nuclear data. This allows us to make conclusions about the spin-flip pomeron behavior and its impact.
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The Two-Higgs-Doublet model (2HDM) is a simple and viable extension of the Standard Model with a scalar potential complex enough that two minima may coexist. In this work we investigate if the procedure to identify our vacuum as the global minimum by tree-level formulas carries over to the one-loop corrected potential. In the CP conserving case, we identify two distinct types of coexisting minima --- the regular ones (moderate $\tan\beta$) and the non-regular ones (small or large $\tan\beta$) --- and conclude that the tree level expectation fails only for the non-regular type of coexisting minima. For the regular type, the sign of $m^2_{12}$ already precisely indicates which minima is the global one, even at one-loop.
Guided us by the scenario of weak scale naturalness and the possible existence of exotic resonances, we have explored in a SO(5) Composite Higgs set-up the interplay among three matter sectors: elementary, top partners and vector resonances. We parametrise it through explicit interactions of spin-1 SO(4)-resonances, coupled to the SO(5)-invariant fermionic currents and tensors presented in this work. Such invariants are built upon the Standard Model fermion sector as well as top partners sourced by the unbroken SO(4). The mass scales entailed by the top partner and vector resonance sectors will control the low energy effects emerging from our interplaying model. Its phenomenological impact and parameter spaces have been considered via flavour-dijet processes and electric dipole moments bounds. Finally, the strength of the Nambu-Goldstone symmetry breaking and the extra couplings implied by the top partner mass scales are measured in accordance with expected estimations.
We present the minimal model of electroweak baryogenesis induced by fermions. The model consists of an extension of the Standard Model with one electroweak singlet fermion and one pair of vector like doublet fermions with renormalizable couplings to the Higgs. A strong first order phase transition is radiatively induced by the singlet- doublet fermions, while the origin of the baryon asymmetry is due to asymmetric reflection of the same set of fermions on the expanding electroweak bubble wall. The singlet-doublet fermions are stabilized at the electroweak scale by chiral symmetries and the Higgs potential is stabilized by threshold corrections coming from a multi-TeV ultraviolet completion which does not play any significant role in the phase transition. We point out that fermion induced electroweak baryogenesis has irreducible phenomenology at the 13 TeV LHC since the new fermions must be at the electroweak scale, have electroweak quantum numbers and couple strongly with the Higgs.
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Numerous new physics models, e.g., theories with extra dimensions and various gauge-group extensions of the standard model, predict the existence of new particles decaying to leptons and photons. This talk presents CMS searches for new resonances in the dilepton, lepton+MET, diphoton, and other final states that include leptons and photons, focusing on the recent results obtained using data collected during the 2016 run.
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Supersymmetry is one of the best-studied extension of the standard model of particle physics. The talk summarizes the results of searches for supersymmetry performed with the CMS experiment using proton-proton collisions at a centre-of-mass energy of 13 TeV. The searches cover a wide spectrum of final states and are interpreted in the framework of several supersymmetric models.
We consider a scenario inspired by natural supersymmetry, where neutrino data is explained within a low-scale seesaw scenario. We extend the Minimal Supersymmetric Standard Model by adding light right-handed neutrinos and their superpartners, the R-sneutrinos, and consider the lightest neutralinos to be higgsino-like. We consider the possibilities of having either an R-sneutrino or a higgsino as lightest supersymmetric particle. Assuming that squarks and gauginos are heavy, we systematically evaluate the bounds on slepton masses due to existing LHC data.
Torsion models constitute a well known class of extended quantum gravity models. In this work, one investigates phenomenological consequences of a torsion field interacting in different ways with top quarks at LHC. A torsion field could appear as a new heavy state characterized by its mass and couplings to fermions. This new state would form a resonance decaying into a top anti-top pair. The latest ATLAS results with 13 TeV data are used to set limits on torsion parameters.
The integrated luminosity needed to observe torsion resonance at the next LHC upgrades are also evaluated, considering different values for the torsion mass and its couplings to Standard Model fermions. Finally, prospects for torsion exclusion at the future LHC phase II and phase III are obtained.
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A brief review of the physics of systems including higher derivatives in the Lagrangian is given. All such systems involve ghosts, i.e. the spectrum of the Hamiltonian is not bounded from below and the vacuum ground state is absent. Usually this leads to collapse and loss of unitarity. In certain special cases, this does not happen, however: ghosts are benign.
We speculate that the Theory of Everything is a higher-derivative field theory, characterized by the presence of such benign ghosts and defined in a higher-dimensional bulk. Our Universe represents then a classical solution in this theory, having the form of a 3-brane embedded in the bulk.
Results of investigations into the possibility of stable tetraquarks using both HQET and Lattice QCD calculations are presented. The existence of some stable tetraquarks containing heavy quarks is found. For such tetraquarks, the opportunities for observation at the LHC is explored. In particular, if a $b b \bar b \bar b$ tetraquark exists below $\eta_b \eta_b$ threshold, it would be narrow and would be observable in the $\Upsilon \Upsilon^*$ decay mode.
Physical Review Letters is the most cited journal in physics, with a Letter
cited roughly every 80 seconds. Editors decide what to publish with extensive
input from peer review and consultation with the PRL editorial board. This
talk will provide an outline of how PRL manages the review of more than 10,000
annual submissions, less than 1/4 of which are published, while maintaining the
breadth and exclusivity that is the hallmark of the journal.
We face many challenges, however, as the publishing trends in some areas of
physics shift, for example to smaller, less comprehensive, or more
interdisciplinary venues. I will discuss some of these challenges, and what PRL
is doing, to maintain a competitive journal that best serves the physics community.
Most importantly, I welcome your feedback during and after the talk.
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We embed a thermal dark matter (DM) candidate within the clockwork framework. This mechanism allows to stabilize the DM particle over cosmological time because it suppresses its decay into Standard Model (SM) particles. At the same time, pair annihilations are unsuppressed, so that the relic density is set by the usual freeze-out of the DM particle from the thermal bath. The slow decay of the DM candidate is induced by “clockwork” particles that can be quite light (rather than at some GUT or Planck scale) and could be searched for at current or future colliders. According to the scenario considered, the very same particles also mediate the annihilation process, thus providing a connection between DM annihilation and DM decay, and fixing the mass scale of the clockwork states, otherwise unconstrained, to be in the TeV range or lighter. We then show how this setup can minimally emerge from the deconstruction of an extra dimension in flat spacetime. Finally, we argue that the clockwork mechanism that we consider could induce Majorana neutrino masses, with a seesaw scale of order TeV or less and Yukawa couplings of order unity.
Probing light dark matter via direct detection is impeded by the low energy carried by light dark matter particles. I will present ways that can bypass the kinematic limitations thus enabling direct detection experiments to probe dark matter candidates in the sub-GeV region using certain inelastic channels, as well as dark matter particles that have been accelerated to high momenta after reflecting off nuclei in the Sun. The talk will be based on the following papers:
1.Phys.Rev.Lett. 118 (2017) no.3, 031803
2.JCAP 1710 (2017) no.10, 031
3.Phys.Rev. D96 (2017) no.1, 015018
We report on the latest searches for low mass states predicted in several New Physics models performed with the data collected by the BaBar detector at the PEP-II $e^+e^-$ collider.
In particular, we search for single-photon events in a sample corresponding to 53 fb$^{−1}$ of $e^+e^− $ collision data. We look for events with a single high-energy photon and a large missing momentum and energy, consistent with production of a spin-1 particle $A’$ through the process $e^+e^- \to \gamma A’$, $A’ \to invisible$. Such particles, referred to as “dark photons”, are motivated by theories applying a $U(1)$ gauge symmetry to dark matter.
We find no evidence for such processes and set $90\%$ confidence level upper limits on the
coupling strength of $A’ \to e^+e^-$ for a dark photon with a mass lower than 8 GeV.?
In particular, our limits exclude the values of the $A’$ coupling suggested by the
dark-photon interpretation of the muon $(g-2)$ anomaly, as well as a broad range of parameters.
We also present a search for a new muonic dark force mediated by a
gauge boson ($Z’$) coupling only to the second and third lepton families.
The existence of the $Z’$ boson is probed in $e^+e^− \to \mu^+\mu^- Z’$, $Z’ \to \mu^+ \mu^-$ events,
No significant signal is observed. Limits on dark-sector coupling constants
are derived, improving the current constraints to the allowed parameter space.
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We present a new method to interpret the γ-ray data of our inner Galaxy as measured with the Fermi Large Area Telescope (Fermi LAT). We train and test convolutional neural networks with simulated Fermi-LAT images based on models tuned to real data. We use this method to investigate the origin of an excess emission of GeV γ-rays seen in previous studies. Interpretations of this excess include γ rays created by the annihilation of dark matter particles and γ rays originating from a collection of unresolved point sources, such as millisecond pulsars. Our new method allows precise measurements of the contribution and properties of an unresolved population of γ-ray point sources in the interstellar diffuse emission model. In a follow-up work we will apply this method to real data using an updated list of detected point sources in order to infer properties of the point source population below the Fermi detection threshold in the Galactic Center area.
The atomic nucleus is one of the most complex strongly-interacting many-body Fermionic systems in nature. A main challenge in describing nuclei is understanding the short interparticle part of the nuclear wave function. Recent high-energy proton and electron scattering experiments show that short-range interactions between the nucleons form correlated, high-momentum, neutron-proton pairs, known as Short-Range Correlations (SRC). There measurements suggest that these correlations account for 20% of the nucleons in the nucleus, and 60-70% of the kinetic energy carried by nucleons in nuclei, thereby having large implications to the modification of the bound nucleon structure function and more.
In this talk I will overview the experimental studies of SRC in nuclei with emphasis on new results on asymmetric nuclei and intriguing developments of effective theories for short-range physics that follow the experimental results. Given time I will also discuss some of the wide-ranging the implications of SRCs for various phenomena, including the isospin dependence of the bound nucleon wave function, the nuclear symmetry energy and the structure of neutron stars and more.
The propagation of colored quarks through the strongly interacting nuclear medium and subsequent formation of hadrons are the phenomena related to the fundamental processes in QCD. There are many experimental tools which can be employed to study those processes. In this talk I will present two results based on the measurements of hadronic final states produced with 5 GeV electron beam in the fixed target experiment in Jefferson Lab. We measured modification of hadron yields on the C, Fe, and Pb targets normalized to D in deep inelastic scattering regime. Analysis of these data addresses the study of quark propagation and hadron formation mechanisms. The measurement of exclusive $\rho^0$ production on a nuclear target relative to deuterium confirms QCD prediction for color transparency and formation of small size configuration.
The electromagnetic form factors of the nucleon are essential for our under- standing of the structure of the nucleon. Precision measurements of nucleon form factors constitute a key part the Jefferson Lab experimental program. The proton Radius experiment (pRad), the first experiment to be completed following the 12 GeV beam upgrade of Jefferson lab, measured the proton form factor down to very low values of Q2 for a high precision extraction of the proton charge radius. The results from this experiment will be vital for resolving the proton charge radius puzzle. The 12 GeV beam upgrade of Jefferson lab combined with new spectrom- eters such as Super Bigbite Spectrometer (SBS), make possible a new generation of experiments to measure nucleon form factors with high precision at high Q2 values. These experiments will allow high resolution determination of the nucleon distribution of charge and magnetization as well as insight into the behavior of the u-and d-quark form factors up to high momentum transfer. In this presentation I will review the achievements of the nucleon form factor program from the Jeffer- son lab 6-GeV era as well as the future form factor experiments with the 12 GeV beam.
A new analysis of published experimental data from the HERMES experiment has been performed. This analysis extracts new information on the space-time properties of color propagation through fitting to a geometric model of the interaction with a realistic nuclear density distribution. Our approach uses a simultaneous fit to the transverse momentum broadening observable and the hadronic multiplicity ratio; the simultaneous fit to two differ- ent observables strongly constrains the outcome. We extract the color lifetime, or production time, for the first time. We also extract estimates for the qˆ transport coefficient characteriz- ing the strength of the interaction between the quark and the cold nuclear medium transverse to the direction of the quark. With a three-parameter model we obtain satisfactory fits to the data for the kinematic conditions approximately corresponding to the current fragmentation region. Quark energy loss was also parametrized using a 4-parameter variant of the model, and it was found not to play a significant role in describing the data. We note the important impact of the functional form of the distribution of production lengths on present and future data. Using simple kinematic arguments, we use these results to predict the color lifetime for typical kinematic conditions for 5 GeV measurements at Jefferson lab, for 11 GeV beam at the upgraded Jefferson Lab, and at the energies of the future Electron-Ion Collider.
The HERMES experiment collected from 1995 to 2007 a wealth of deep-inelastic scattering data using 27.6 GeV longitudinally polarized electrons and positrons and various unpolarized as well as longitudinally and transversely polarized gas targets. This allowed for a series of diverse measurements. Among them are measurements that provide information on the three-dimensional structure of the nucleon both in momentum space and in mixed momentum and position space. Results from HERMES on semi-inclusive deep-inelastic scattering, providing access to the three-dimensional quark distributions in momentum space, as well as on hard exclusive processes, sensitive to generalized parton distributions and thus to the three- dimensional nucleon structure in mixed momentum and position space, are presented and discussed.
We provide a universal expression of cross sections for the exclusive vector meson production and deeply virtual Compton scattering (DVCS) in photon-proton and photon-nucleus interactions based on the geometric scaling phenomenon. The theoretical parametrization based on the scaling property depends only on the single variable $\tau_A = \frac{Q^2}{Q_{sat}^2}$, where the saturation scale, $Q_{sat}$, drives the energy dependence and the corresponding nuclear effects. This phenomenological result describes all available data from DESY-HERA for $\rho,\phi$ and $J/\psi$ production and DVCS measurements. A discussion is also carried out on the size of nuclear shadowing corrections on photon-nucleus interaction.
This work has been published in the following paper https://journals.aps.org/prd/abstract/10.1103/PhysRevD.96.054015
We show that the effective field equations for a recently formulated
polynomial affine model of gravity,
in the sector of a torsion-free connection, accept general Einstein
manifolds—with or without cosmological
constant—as solutions. Moreover, the effective field equations are
partially those obtained from a gravitational
Yang–Mills theory known as Stephenson–Kilmister–Yang theory.
Additionally, we find a generalization of a
minimally coupled massless scalar field in General Relativity within a
“minimally” coupled scalar field in this
affine model. Finally, we present a brief (perturbative) analysis of
the propagators of the gravitational theory,
and count the degrees of freedom. For completeness we prove that a
Birkhoff-like theorem is valid for the
analyzed sector.
In the present work the set of stationary solutions of the Gross-Neveu model in t'Hooft limit is extended. Such extension is obtained striving a hidden supersymmetry associated to disconnected sets of stationary solutions. It is shown how the supersymmetry arises from the Darboux-Miura transformations between Lax pairs of stationary modified Korteweg-de Vries and the stationary Korteweg-de Vries hierarchies, associating the correspondent supercharges to self-consistent condensates for the Gross-Neveu model.
Baryon spectroscopy began in 1952 with the discovery of the first Δ resonance by Fermi and collaborators. By the mid-1980s a sizeable collection of resonances had been identified in pion-Nucleon scattering, and particle physics left this field for higher-energy pastures, confident that a basic understanding of the Nstar spectrum was at least close, if not exactly in hand. With time, refinements of the quark model provided a systematic ordering to the observations but, annoyingly, predicted the existence of many more states than had been observed, which lead to speculations of mechanisms that restricted the degrees of freedom. Only recently (2011) have theoretical advances finally allowed a direct computation of the nucleon spectrum in Lattice-QCD, with the startling confirmation of large numbers of “missing” excited states. With the advent of new facilities, the last decade has seen a renaissance of sorts in photo-meson production experiments, in which polarization has been used to constrain the production amplitudes to a degree not achieved in π+N reactions, and a great many new Nstar candidates are emerging. The additional flexibility in the 4-momentum transfer has been used with electron scattering to probe the excitation process and the role of the meson cloud. Highlights in the context of the CLAS N* spectroscopy program at Jefferson Lab will be reviewed.
Since the discovery of the EMC effect over 30 years ago, it’s been of great theoretical interest and studied in several experimental measurements. No unified picture arose to explain the underlying cause of per nucleon structure function modification in nuclei. Precise measurements on light nuclei from JLab’s 6 GeV era revitalized this research by showing that traditional A or density dependent models of this nuclear modification do not work. The measurements will be reviewed with results from data on heavy targets from JLab's E03-103 presented. Upcoming measurements will also be discussed.
The A2 Collaboration in the Crystal Ball/TAPS experiment at the MAMI accelerator
facilty in Mainz, Germany has a diversi?ed research program using real photons. The
Crystal Ball/TAPS setup has the ability to provide almost full coverage in solid angle and
is well suited to detect multi particle ?nal states. The experiments use high intensity circu-
larly, linearly, or unpolarized photon beams and unpolarized or polarized targets. To fully
understand the strong interaction in the non-pertubative region, the excitation spectrum
of nucleons is an important tool to exploit. Comparing experimentally observed excited
nucleon states to model predictions or lattice QCD calculations, large discrepancies arise,
speci?cally concering the number of states. The electromagnetic coupling of photons to
protons is di?erent than that of neutrons in certain states. A complete partial wave anal-
ysis (PWA) can assist in yielding more information about any reaction with polarization
observables playing a crucial role, as well as measurements of cross-sections. Spin observ-
ables are essential in disentangling the contributing resonant and non-resonant amplitudes,
whereas cross-section data alone is not su?cient for separating resonances. Recent results,
the current status, and future plans of the A2 Collaboration will be discussed.
Nucleon polarisabilities are fundamental structure observables, like mass
or charge, which are sensitive to the internal quark dynamics of the nucleon.
Polarised Compton scattering off the proton can be used to study the polarisabilities
of the proton, thus probing the internal structure of the proton.
Scalar terms quanitify the response of the proton’s structure to an applied
electromagnetic field, while spin dependent terms similarly quantify the response
of the proton’s spin. The leading order scalar polarisabilities are
denoted by αE1 and βM1, while the leading order spin polarisabilities are denoted
by ¯γE1E1, ¯γM1M1, ¯γE1M2, and ¯γM1E2. An experimental program, using
polarised Compton scattering with the Crystal Ball experiment at MAMI,
will be discussed. Recent results will be presented.
TBD
TBD
ALICE is the experiment at the LHC devoted to the study of the strongly-interacting matter produced at high temperature and high energy density in ultra-relativistic heavy-ion collisions. In parallel with the successful operation of the experiment and with the rich physics output obtained during the first two runs of the LHC, the ALICE collaboration is working on a major upgrade of its detector. The main physics goal of this upgrade is the improvement of the precision of heavy flavours, quarkonia, direct real and virtual photons, jets and low-mass dileptons, with particular emphasis on their production in the low momentum region. The general upgrade strategy, which will be deployed during the second LHC long shutdown (LS2, 2019-2020) in view of the LHC Runs 3 and 4 (2021 to 2029), is conceived to deal with expected Pb-Pb interaction rates up to 50 kHz with the goal of integrating the luminosity to the order of 10 nb$^{-1}$.
In this presentation, we will discuss the modifications and replacements needed in the ALICE detector: the new GEM-based readout chambers of the TPC, the new pixel silicon trackers (Inner Tracking System and Muon Forward Tracker), the new readout and trigger architecture and the new online-offline computing facility.
The ATLAS detector at the Large Hadron Collider (LHC) has had an extremely successful
data collecting period during 2017, recording over 45 fb-1 of proton-proton collision data at
sqrt(s) = 13 TeV. This was achieved, in part, by running the LHC at a high instantaneous lumi-
nosity level of over 1.5 x 10+34 cm-2s-1, which corresponds to over 57 inelastic proton-proton
collisions per beam crossing. This talk will highlight the tracking and vertexing performance
of the tracking detector within ATLAS (Inner Detector) throughout this successful year of
data taking.
In order to increase its potential for discoveries, the High Luminosity Large Hadron Collider
(HL-LHC) aims to increase the LHC data-set by an order of magnitude by collecting 3,000
fb-1 of recorded data. Starting, from mid-2026, the HL-LHC is expected to reach the peak
instantaneous luminosity of 7.5 x 10+34 cm-2s-1, which corresponds to about 200 inelastic
proton-proton collisions per beam crossing. To cope with the large radiation doses and high
pileup, the current ATLAS Inner Detector will be replaced with a new all-silicon Inner Tracker.
The expected tracking and vertexing performance with the HL-LHC tracker is also presented in
this talk, highlighting the challenges encountered in data taking in a high pileup environment.
The Belle II experiment is a substantial upgrade of Belle detector and will operate at the SuperKEKB energy-asymmetric $e^+e^-$ collider. The detector is in its final phase of construction and the accelerator has successfully completed the first phase of commissioning. The design luminosity of $8 \times 10^{35}$ cm$^{-2}$s$^{-1}$ and the Belle II experiment aims to record 50 ab$^{-1}$ of data, a factor of 50 more than the Belle experiment. This large data set will be accumulated with low backgrounds and high trigger efficiencies in a clean $e^+e^－$ environment; it will allow to probe New Physics scales that are well beyond the reach of direct production at the LHC and will complement the searches through indirect effects that are currently ongoing or planned. This talk will review the present status of the detector upgrade, and present an overview of the golden channels, their physics motivations, and the expected sensitivity.
TBD
The Higgs boson discovered at the LHC has completed the standard model of particle physics. The LHC run2 with a center of mass energy of 13 TeV is now in progress, where properties of the Higgs boson and other particles are measured to be consistent with expectations of the standard model and no indication of new particles has been observed up to now. The International Linear Collider (ILC) is an electron positron linear collider with superconducting radio frequency technology, with center of mass energies from 250 GeV to 500 GeV, extendable to 1 TeV and beyond, and the realization of the ILC as an international project is officially under discussion in Japan. In this talk, physics and detectors at the ILC as well as the project status, including the recent ICFA statement of ILC 250 GeV as a Higgs boson factory, are presented.
The Compact Linear Collider (CLIC) is a proposed
high-luminosity linear electron-positron collider at the energy
frontier. For optimal physics potential CLIC is foreseen to be built and
operated in a staged approach, with three centre-of-mass energy stages;
ranging from a few hundred GeV up to 3 TeV. The initial energy stage is
planned to operate just above the top-quark pair production threshold
around 380 GeV, with focus on precision measurements of the Higgs-boson
and the top-quark properties. Reaching precisions beyond the HL-LHC
reach, this programme further provides very competitive constraints on
models describing physics beyond the Standard Model. The subsequent
energy stages of CLIC will focus on measurements of rare Higgs-boson
processes, as well as direct and indirect searches for new physics, and
precision measurements of possible new particles. This talk will
summarise and discuss analysis results from the Higgs physics programme
and the top-quark physics programme. The results presented are based on
full detector simulations including relevant background processes.
We present angular diameter distance measurements obtained by locating the
BAO scale in the distribution of galaxies selected from the first year of Dark
Energy Survey data. We consider a sample of over 1.3 million galaxies
distributed over a footprint of 1318 deg$^2$ with $0.6 < z_{\rm photo} < 1$ and
a typical redshift uncertainty of $0.03(1+z)$. This sample was selected using a color/magnitude selection that
optimizes trade-offs between number density and redshift uncertainty. We
investigate the BAO signal in the projected clustering using three conventions,
the angular separation, the co-moving transverse separation, and spherical
harmonics. Further, we compare results obtained from template based and machine
learning photometric redshift determinations. We use 1800 simulations that
approximate our sample in order to produce covariance matrices and allow us to
validate our distance scale measurement methodology. We measure the angular
diameter distance, $D_A$, at the effective redshift of our sample divided by
the true physical scale of the BAO feature, $r_{\rm d}$. We obtain close to a 4
per cent distance measurement of $D_A(z_{\rm eff}=0.81)/r_{\rm d} = 10.75\pm
0.43 $. These results are consistent with the flat $\Lambda$CDM concordance
cosmological model supported by numerous other recent experimental results.
HAWC is an array of 300 large volume water Cherenkov detectors spread over an area of 20,000 square meters situated at 4,100 m altitude in the mountains of central Mexico. It detects continuously TeV air showers over a large field of view of 2 sr observing 2/3 of the sky each day and is able to separate gamma rays from cosmic rays utilizing the differences between electromagnetic and hadronic shower topologies. The first HAWC gamma ray catalog with 18 months of data identified ~40 sources of which one quarter were previously unknown. Two extragalactic blazers Markarian 421 and Markarian 501 show strong flaring activity in the daily light curve measurements. Now more than 30 months of data are available. In the galactic plane HAWC has discovered large TeV halos around nearby middle aged pulsars like Geminga and Monogem that strongly constraint their contribution at Earth to the positron excess measured by the PAMELA, Fermi and AMS detectors in space. In the surveyed sky there are many dark matter rich objects like dwarf and irregular galaxies whose analysis have placed the strongest constraints up to date on annihilating or decaying dark matter with masses of more then 10 TeV. The large field of view of HAWC has allowed us to make several multi-wavelength and multi-messenger observations with gamma-ray satellites (Fermi), gravity-wave detectors (LIGO-Virgo) and neutrino observatories (IceCube).
Lorentz Invariance Violation (LIV) has been investigated by several theories and tested by numerous experiments. Ultra-high energy cosmic rays (UHECR) are the most energetic particles known in the Universe and, since LIV is supposed to be suppressed in lower energies, they have been proposed as a suitable test for LIV. The Pierre Auger Observatory is the largest observatory designed to detect such particles. It is located in Argentina and consists of 1660 water tanks and 27 fluorescence telescopes. In this work, we study the capability of testing LIV in the hadron sector by using the UHECR spectrum and composition measured by the Pierre Auger Observatory. To obtain that, the propagation of UHE protons and nuclei has been changed by introducing LIV in the kinematics of the pion production and the photodisintegration. This results in changes in the energy losses of UHECR and, consequently, in possible changes in the spectrum. Finally, a fit of both spectrum and composition measured by Auger have been performed considering the LIV propagation.
NA61/SHINE is a fixed target experiment designed to study
hadron-proton, hadron-nucleus and nucleus-nucleus interactions at the
CERN Super-Proton-Synchrotron. In this contribution we will discuss
results from pion-carbon collisions recorded at beam momenta of 158
and 350 GeV/c. Hadron production measurements in this type of
interactions is of fundamental importance for the understanding of the
muon production in extensive air showers. In particular, production of
(anti)baryons is one of the mechanisms responsible for increasing the
number of muons in air shower. A possible underestimation of the
production rate of (anti)baryons in current hadronic interaction
models could be one of the sources of the excess of muons observed by
cosmic ray experiments, like Pierre Auger Observatory. The results on
the production spectra of $\pi^{\pm}$, K$^{\pm}$, $p(\bar{p})$,
$\Lambda(\bar{\Lambda})$ and K$_S^0$ will be presented, as well as
their comparison to predictions of hadronic interaction models
currently used in air shower simulations.
The CSES mission is a sophisticated multi-channel space observatory for seismic phenomena. It looks for correlation between electromagnetic perturbations, plasma density transients and charged particle flux variations. The HEPD is the CSES instrument sensitive to charged particles in the range of 30-300 MeV/nucleon (10-150 MeV for electrons). It is also an extremely precise detector to study other space weather phenomena: Van Allen belts, solar modulation, coupling of inter-planetary and geomagnetic field. The CSES launch is scheduled for February 2nd 2018 and all preliminary tests for the commissioning phase have been performed, both with calibration beams at laboratories and with atmospheric muons. The HEPD performance as estimated from these tests will be shown.
Recent results of soft QCD measurements performed by the ATLAS collaboration are reported. The measurements include total, elastic and inelastic cross sections, inclusive spectra, underlying event and particle correlations in p-p and p-Pb collisions.
We study the correlation length between test quarks with the same electric and color charges in the Nambu–Jona-Lasinio model, considering thermal and magnetic effects. We extract the correlation length from the quark correlation function. The latter is constructed from the probability amplitude to bring a given quark into the plasma, once a previous one with the same quantum numbers is placed at a given distance apart. For temperatures below the transition temperature, the correlation length starts growing as the field strength increases to then decrease for large magnetic fields. For temperatures above the pseudocritical temperature, the correlation length continues increasing as the field strength increases. We found that such behavior can be understood as a competition between the tightening induced by the classical magnetic force versus the random thermal motion. For large enough temperatures, the increase of the occupation number contributes to the screening of the interaction between the test particles. The growth of the correlation distance with the magnetic field can be understood as due to the closer proximity between one of the test quarks and the ones popped up from vacuum, which in turn appear due to the increase of the occupation number with temperature.
The clustering of color sources has been successful in describing several phenomena of multiparticle production, and collectivity signatures of strongly interacting partonic matter in relativistic heavy-ion collisions from the initial stage. Moreover, in small collision systems, the size effects in critical string density becomes relevant, and its contribution to the system properties differ from those in heavy ion collision near the thermodynamical limit.
We present a study in terms of the corresponding values of the ratio of (shear vs. bulk) viscosity and entropy density (η/s, ζ/s) for the high multiplicity proton-proton (pp) and (pPb) collision data at LHC energies.Results are above AdS/CFT and Conformal Field Theory boundaries.
TBD
We formulate a predictive model of fermion masses and mixing based on a $\Delta(27)$ family symmetry. In the quark sector the model leads to the viable mixing inspired texture where the Cabibbo angle comes from the down quark sector and the other angles come from the up quark sector. In the lepton sector the model generates a predictive structure for charged leptons and, after radiative seesaw, an effective neutrino mass matrix with only one real and one complex parameter.
We carry out a detailed analysis of the predictions in the lepton sector, where the model is only viable for inverted neutrino mass hierarchy, predicting a strict correlation between $\theta_{23}$ and $\theta_{13}$. We show a benchmark point that leads to the best-fit values of $\theta_{12}$, $\theta_{13}$, predicting a specific $\sin^2\theta_{23} \simeq 0.51$ (within the $3 \sigma$ range), a leptonic CP-violating Dirac phase $\delta \simeq 281.6 ^\circ$ and for neutrinoless double-beta decay $m_{ee} \simeq 41.3$ meV.
We turn then to an analysis of the dark matter candidates in the model, which are stabilized by an unbroken $\mathbb{Z}_2$ symmetry. We discuss the possibility of scalar dark matter, which can generate the observed abundance through the Higgs portal by the standard WIMP mechanism. An interesting possibility arises if the lightest heavy Majorana neutrino is the lightest $\mathbb{Z}_2$-odd particle. The model can produce a viable fermionic dark matter candidate, but only as a feebly interacting massive particle (FIMP), with the smallness of the coupling to the visible sector protected by a symmetry and directly related to the smallness of the light neutrino masses.
Neutrinoless double beta decay ($0\nu\beta\beta$), being a lepton
number violating (LNV) process, offers an opportunity
to probe physics beyond the SM in a way complementary or maybe even unavailable for collider experiments. Its non-observation allows to
constrain LNV beyond standard model (BSM) physics. There are two different kind of
contributions to the $0\nu\beta\beta$ amplitude: the short-range mechanisms
(SRM), which are mediated by heavy particle
exchange; and the long-range mechanisms (LRM), in
which a light neutrino is exchanged between two point-like vertices.
Here we calculate the leading order QCD corrections to both the SRM and LRM. It is shown that this QCD corrections are
important, especially in the SRM case \cite{Gonzalez:2015ady} due the
presence of the color-mismatch effect and the corresponding mixing of
different operators, with numerically very different nuclear matrix
elements (NME). This effect leads to differences in the limits on the
Wilson Coefficients (WC) in some cases up to 3 orders of
magnitude. On the other hand, the LRM operate between two different
and distant nucleons, so that no color-mismatch appears and only QCD
vertex corrections have to be taken into account. Their effect on the
extracted limits does not exceed 60\% \cite{Arbelaez:2016zlt}, less
than the typical estimate of the uncertainties of the nuclear matrix
elements (NMEs). The impact of QCD corrections on high-scale models (HSM) can be also analysed \cite{Arbelaez:2016uto}. In the SRM for instance, all HSM match at some scale around a $\sim$ few TeV
with the corresponding effective theory, containing a certain set of
effective dimension-9 operators. Many of these HSM receive
contributions from more than one of the basic operators and we
calculate limits on these models using the latest experimental data. \ \
These QCD RGE results \cite{Gonzalez:2015ady,Arbelaez:2016zlt} are
valid for energy scales above $\sim 1$ GeV - the limit of perturbative
QCD, while the typical scale of $0\nu\beta\beta$-decay is about
$\sim 100$ MeV. In view of this fact we examine the possibility of
extrapolating the perturbative results towards sub-GeV
non-perturbative scales on the basis of the QCD coupling constant
freezing'' behavior using Background Perturbation Theory \cite{Gonzalez:2017mcg}. Our
analysis suggests that such an infrared extrapolation does modify the
perturbative results for both SRM and
LRM of $0\nu\beta\beta$-decay in general only
moderately. However, out of a total of nine short-range
Wilson coefficient there is one, the tensor$\otimes$tensor effective
operator, which depends sensitively on the exact numerical value of
the
frozen'' $\alpha_S$. Fortunately, this operator can not
appear alone in the low-energy limit of any renormalizable
high-scale model. We show that all five linearly independent
combinations of the scalar and tensor operators, that can appear in
renormalizable models, are infrared stable.
The evasive nature of Dark Matter (DM) has been challenging experimentalists and theorists alike for decades. In order to bridge both approaches, we investigate the phenomenology that two different simplified models would imprint on various experiments, stressing the importance of the complementarity that they offer. We start by analysing the dark sequential $Z'$ portal, where direct detection and collider searches put the strongest bounds on this simplified model with a Majorana fermion as the DM candidate. Then we move on to consider a heavy right-handed neutrino as the mediator between the Standard Model and the dark sector and get constraints coming from indirect detection searches.
Leptoquarks occur in many new physics scenarios and could be the
next discovery at the LHC. In this talk we point out that
a model-independent search strategy covering all possible leptoquarks is
possible and has not yet been fully exploited. To be systematic we organize
the possible leptoquark final states according to a leptoquark matrix with
entries corresponding to nine experimentally distinguishable leptoquark
decays: any of {light-jet, b-jet, top} with any of { neutrino, e/mu; tau}. The
9 possibilities can be explored in a largely model-independent fashion
with pair-production of leptoquarks at the LHC. We review the status
of experimental searches for the 9 components of the leptoquark matrix,
pointing out which 3 have not been adequately covered. We plead that
experimenters publish bounds on leptoquark cross sections as functions of
mass for as wide a range of leptoquark masses as possible. Such bounds are
essential for reliable recasts to general leptoquark models. To demonstrate
the utility of the leptoquark matrix approach we collect and summarize
searches with the same final states as leptoquark pair production and use
them to derive bounds on a complete set of Minimal Leptoquark models
which span all possible flavor and gauge representations for scalar and
vector leptoquarks.