Thu·Jan 17, 2019Thursday·January 17, 2019

1. 01*

   Analysis of the $D{\bar{D}}^{\ast }K$ system with QCD sum rules

   Zun-Yan Di🇨🇳 · Zhi-Gang Wang🇨🇳

   In this article, we construct the color singlet-singlet-singlet interpolating current with $I\left(J^P\right)=\frac{3}{2}\left(1^{-}\right)$ to study the $D{\bar{D}}^{\ast }K$ system through QCD sum rules approach. In calculations, we consider the contributions of the vacuum condensates up to dimension-16 and employ the formula $\mu =\sqrt{M_{X/Y/Z}^2-{\left(2{\mathbb{M}}_c\right)}^2}$ to choose the optimal energy scale of the QCD spectral density. The numerical result $M_Z=4.71_{-0.11}^{+0.19}\mathrm{GeV}$ indicates that there exists a resonance state $Z$ lying above the $D{\bar{D}}^{\ast }K$ threshold to saturate the QCD sum rules. This resonance state $Z$ may be found by focusing on the channel $J/\psi \pi K$ of the decay $B⟶J/\psi \pi \pi K$ in the future.

   hep-phAdv.High Energy Phys.(2019)·7 citations
2. 02*

   Ratio of the structure functions and the color dipole model bound

   G.R.Boroun🇮🇷 · B.Rezaei🇮🇷

   We observe that the DGLAP evolution equations at NNLO analysis predicts a ratio of the structure functions in region of small Bjorken variable $x$. The ratio $F_L(x,Q^2)/F_2(x,Q^2)$ is obtained and compared with the prediction of the dipole model and HERA data. In particular we show that this ratio is lower than dipole model bound at high-$Q^2$ values and it is higher at low-$Q^2$ values . Then the effect of adding a higher twist term to the description of the ratio $F_L(x,Q^2)/F_2(x,Q^2)$ for $Q^2<20Ge{V}^2$ is investigated. Also the bounds are discussed by including charm distribution on $F_L/F_2$. We discuss, furthermore, how this ratio can be determine the proton structure function with respect to the reduced cross section at high-$y$ values.

   hep-phNPA(2019)·11 citations
3. 03*

   Construction of RG improved effective potential in a two real scalar system

   Hideaki Ookane🇯🇵

   We study the improvement of effective potential by renormalization group (RG) equation in a two real scalar system. We clarify the logarithmic structure of the effective potential in this model. Based on the analysis of the logarithmic structure of it, we find that the RG improved effective potential up to $L$-th-to-leading log order can be calculated by the $L$-loop effective potential and $(L+1)$-loop $\beta$ and $\gamma$ functions. To obtain the RG improved effective potential, we choose the mass eigenvalue as a renormalization scale. If another logarithm at the renormalization scale is large, we decouple the heavy particle from the RG equation and we must modify the RG improved effective potential. In this paper we treat such a situation and evaluate the RG improved effective potential. Although this method was previously developed in a single scalar case, we implement the method in a two real scalar system. The feature of this method is that the choice of the renormalization scale does't change even in a calculation of higher leading log order. Following the our method one can derive the RG improved effective potential in a multiple scalar model.

   hep-phPTEP(2019)·7 citations
4. 04*

   Integrated triple-collinear counter-terms for the nested soft-collinear subtraction scheme

   Maximilian Delto🇩🇪 · Kirill Melnikov🇩🇪

   We obtain analytic results for integrated triple-collinear splitting functions that emerge as collinear counter-terms in the context of the nested soft-collinear subtraction scheme arXiv:1702.01352 . With these results, all integrated subtraction terms required for NNLO QCD computations within this scheme are known analytically. In addition to improving efficiency and numerical stability of practical computations, the availability of these results will contribute towards establishing a general NNLO QCD subtraction formula for generic hard scattering processes in hadron collisions, similar to Catani-Seymour and FKS subtractions at NLO.

   hep-phJHEP(2019)·43 citations
5. 05*

   Symmetry-Scaling Based Complex Network Approach to Explore Exotic Hadronic States in High-Energy Collision

   Susmita Bhaduri🇮🇳 · Anirban Bhaduri🇮🇳 · Dipak Ghosh🇮🇳

   Conventionally invariant mass or transverse momentum techniques have been used to probe for any formation of some exotic or unusual resonance states in high energy collision. In this work, we have applied symmetry scaling based complex network approach to study exotic resonance/hadronic states utilizing the clustering coefficients and associated scaling parameter extracted with the complex network based technique of Visibility Graph. We have analyzed the data of Pb-Pb collision data sample at 2.76 TeV from ALICE Collaboration and analyzed different patterns of symmetry scaling, scale-freeness, correlation and clustering among the produced particles. This is a chaos-based complex network technique where simple parameters like Average Clustering Coefficient and Power of Scale-freeness of Visibility Graph(PSVG) may hint at formation of some exotic or unusual resonance states without using conventional methods. From this experiment we may infer that highest range of Average clustering coefficient, might be the resonance states/clusters from where the hadronic decay might have occurred and few clusters with highest value of this parameter may indicate that those clusters may be the ancestors of some strange particles. There have also been extensive study of dilepton production since the study of lepton pair generation in Drell-Yan processes is immensely important as these processes enable us to validate the Standard Model-SM predictions for the fundamental particles interaction at the new energy region and also to probe for new physics beyond SM. Hence we have applied the same methodology and extracted the same parameters for p-p collision data at 8TeV from CMS, to detect possible resonance states eventually generating lepton pairs.

   hep-phhep-exPhys.Part.Nucl.Lett.(2019)·4 citations
6. 06*

   Quantum mechanics aspects and subtleties of neutrino oscillations

   Evgeny Akhmedov🇩🇪

   Neutrino oscillations appear to be a simple quantum mechanical phenomenon. However, a closer look at them reveals a number of subtle points and apparent paradoxes. Some of the basic issues of the theory of neutrino oscillations are still being debated. I discuss, from a historical perspective, how the role of quantum mechanical aspects of neutrino oscillations was realized in the course of the development of the theory of this phenomenon.

   hep-phhep-exnucl-ex48 citations
7. 07*

   Power Corrections to Pion Transition Form Factor in Perturbative QCD Approach

   Yue-Long Shen🇨🇳 · Zhi-Tian Zou🇨🇳 · Ying Li🇨🇳

   In this paper we calculate the power corrections to the pion transition form factor within the framework of perturbative QCD approach on the basis of $k_T$ factorization. The power suppressed contributions from higher twist pion wave functions and the hadronic structure of photon are investigated. We find that there exists strong cancellation between the two kinds contributions, thus the total power corrections considered currently are very small, and the prediction of the leading power contribution with joint resummation improved perturbative QCD approach is almost unchanged. This result confirms that the pion transition form factor is a good platform to constrain the nonperturbative parameters in pion wave functions. Moreover, our result can accommodate the anomalous data from BaBar, or agrees with results from Belle according to the choice of Gegebauer moment in the pion wave function, and the more precise experimental data from Belle-II is expected.

   hep-phPRD(2019)·13 citations
8. 08*

   Hard diffraction in photoproduction with Pythia 8

   Ilkka Helenius🇫🇮 · Christine O. Rasmussen🇸🇪

   We present a new framework for modeling hard diffractive events in photoproduction, implemented in the general purpose event generator Pythia 8. The model is an extension of the model for hard diffraction with dynamical gap survival in pp and ppbar collisions proposed in 2015, now also allowing for other beam types. It thus relies on several existing ideas: the Ingelman-Schlein approach, the framework for multiparton interactions and the recently developed framework for photoproduction in gamma p, gamma gamma, ep and $e^{+}{e}^{-}$ collisions. The model proposes an explanation for the observed factorization breaking in photoproduced diffractive dijet events at HERA, showing an overall good agreement with data. The model is also applicable to ultraperipheral collisions with pp and pPb beams, and predictions are made for such events at the LHC.

   hep-phhep-exEPJC(2019)·29 citations
9. 09*

   Summary of recent progress in searches for additional Higgs bosons

   Martin Flechl🇦🇹

   There has been a tremendous increase of sensitivity in searches for charged Higgs bosons and additional neutral Higgs bosons since the last CHARGED workshop in 2016. We will review recent experimental and theory developments as presented at CHARGED2018, and conclude with future prospects for the field.

   hep-phhep-exPoS(2019)·4 citations
10. 10*

    The PeV-Scale Split Supersymmetry from Higgs Mass and Electroweak Vacuum Stability

    Waqas Ahmed🇨🇳 · Adeel Mansha🇨🇳 · Tianjun Li🇨🇳 · Shabbar Raza🇵🇰 · Joydeep Roy🇨🇳 · Fang-Zhou Xu🇨🇳

    The null results of the LHC searches have put strong bounds on new physics scenario such as supersymmetry (SUSY). With the latest values of top quark mass and strong coupling, we study the upper bounds on the sfermion masses in Split-SUSY from the observed Higgs boson mass and electroweak (EW) vacuum stability. To be consistent with the observed Higgs mass, we find that the largest value of supersymmetry breaking scales $M_S$ for $\tan \beta =2$ and $\tan \beta =4$ are $\mathcal{O}(10^3\mathrm{TeV})$ and $\mathcal{O}(10^{1.5}\mathrm{TeV})$ respectively, thus putting an upper bound on the sfermion masses around $10^3\mathrm{TeV}$. In addition, the Higgs quartic coupling becomes negative at much lower scale than the Standard Model (SM), and we extract the upper bound of $\mathcal{O}(10^4\mathrm{TeV})$ on the sfermion masses from EW vacuum stability. Therefore, we obtain the PeV-Scale Split-SUSY. The key point is the extra contributions to the Renormalization Group Equation (RGE) running from the couplings among Higgs boson, Higgsinos, and gauginos. We briefly comment on the lifetime of gluinos in our study and compare it with current LHC observations. Additionally, we comment on the prospects of discovery of prompt gluinos in a 100 TeV proton-propton collider.

    hep-phPTEP(2020)·3 citations
11. 11*

    The emergence of multi-lepton anomalies at the LHC and their compatibility with new physics at the EW scale

    Stefan von Buddenbrock🇿🇦 · Alan S. Cornell🇿🇦 · Yaquan Fang🇨🇳 · Abdualazem Fadol Mohammed🇿🇦 · Mukesh Kumar🇿🇦 · Bruce Mellado🇿🇦 · Kehinde G. Tomiwa🇿🇦

    A recent study [1] has shown that a simplified model predicting a heavy scalar of mass 270 GeV ($H$) that decays to a Standard Model (SM) Higgs boson in association with a scalar singlet of mass 150 GeV ($S$) can accommodate several anomalous multi-lepton results in proton-proton collisions at the Large Hadron Collider (LHC). With this in mind, the goal of this article is to provide a more formal study of a wider set of LHC results pertaining to the production of multiple leptons. We find that a combination of such results lead to strong discrepancies between the data and SM Monte Carlo predictions. These discrepancies appear in corners of the phase-space where different SM processes dominate, indicating that the potential mismodeling of a single SM process is unlikely to explain them. Systematic uncertainties from the prediction of SM processes evaluated with currently available tools seem unable to explain away these discrepancies. A combination is able to constrain the simplified model's single degree of freedom ${\beta }_g^2$, related to the size of the Yukawa coupling of $H$ to the top quark, to a value of $2.92\pm 0.35$. This is in contrast to the absence of signal, where ${\beta }_g=0$. This result is discussed in the independent contexts of both potential for new physics in the existing LHC data as well as the limitations of our current understanding of the SM. That being said, QCD NNLO and EW NLO corrections in di-lepton final states are not expected to change the conclusions of this study. New results pertaining to the production of two opposite sign different flavour charged leptons with a full jet veto further confirm the presence of anomalies in similar corners of the leptonic phase-space.

    hep-phJHEP(2019)·78 citations
12. 12*

    Spin-Independent Two-Neutrino Exchange Potential with Mixing and $CP$-Violation

    Quan Le Thien🇺🇸 · Dennis E. Krause🇺🇸

    We develop a new approach for calculating the spin-independent 2-neutrino exchange potential (2-NEP) between non-relativistic fermions which places emphasis on the neutrino vacuum state, an area of theoretical interest in recent years. The 2-NEP is a natural probe of fundamental issues of neutrino physics such as neutrino masses, flavor mixing, the number of neutrino flavors, neutrino nature (Dirac or Majorana), $CP$-violation, and the neutrino vacuum state. We explore the dependence of the 2-NEP on the mixing of neutrino mass states assuming normal and inverted mass ordering for nucleon-nucleon, nucleon-lepton, and lepton-lepton interactions, and the $CP$-violation phase in the neutrino mixing matrix.

    hep-phPRD(2019)·22 citations
13. 13*

    Nuclear configurational entropy of the energy-energy correlation in $e^{+}{e}^{-}$ annihilation processes

    G. Karapetyan🇧🇷

    In this paper the nuclear configurational entropy of the energy--energy correlation function is scrutinized, in $e^{+}{e}^{-}$ collisions to hadrons in the back-to-back region, within the QCD perturbative theory. The critical points of the nuclear configurational entropy concept, in the hot nuclear system, is shown to correspond to the critical angle between the two scattered hadrons, corroborating with phenomenological data with great accuracy. The main tools employ the main coefficients of the soft-gluon resummation formula, taking into account logarithmically enhanced contributions up to next-to-next-to-leading logarithmic accuracy.

    hep-phnucl-thEPL(2019)·24 citations
14. 14*

    Decay $\varphi \to Z\gamma \gamma$ ($\varphi =h,H,A$) in the minimal supersymmetric standard model

    R. Sánchez-Vélez🇲🇽 · G. Tavares-Velasco🇲🇽

    The decays of the CP-even ($h,H$) and the CP-odd ($A$) Higgs bosons $h,H,A\to Z\gamma \gamma$ are calculated in the context of the minimal supersymmetric standard model (MSSM), where they are induced at the one-loop level via box and reducible Feynman diagrams. For the numerical evaluation of the branching ratios we employ the decoupling limit and consider values for the MSSM parameters still consistent with the current experimental data. We consider a particular scenario for the radiative corrections to the Higgs boson masses, dubbed hMSSM, which leads to only two free parameters, namely $m_A$ and $\tan \beta$. We found that the branching ratio of the $CP$-odd Higgs boson decay $A\to Z\gamma \gamma$ can reach values up to $10^{-8}$ for $m_A=750$ GeV, which is three order of magnitude smaller than that of the $A\to \gamma \gamma$ channel. On the other hand, the branching ratio of the $H\to Z\gamma \gamma$ decay is of the order of $10^{-7}$ for large values of $m_H$ and small values of $\tan \beta$, which is comparable with the branching ratio of the $H\to Z\gamma$ channel. As far as the branching ratio of the SM-like Higgs boson decay $h\to Z\gamma \gamma$ is concerned, it is considerably suppressed, of the order of $10^{-11}$.

    hep-phPRD(2019)·2 citations
15. 15*

    Higher order corrections to spin correlations in top quark pair production at the LHC

    Arnd Behring🇩🇪 · Michal Czakon🇩🇪 · Alexander Mitov🇬🇧 · Andrew S. Papanastasiou🇬🇧 · Rene Poncelet🇬🇧

    We calculate, for the first time, the next-to-next-to leading order (NNLO) QCD corrections to spin correlations in top quark pair production at the LHC. The NNLO corrections play an important role in the description of the corresponding differential distributions. We observe that the Standard Model calculation describes the available delta-phi data in the fiducial region but does not agree with the delta-phi measurement extrapolated to full phase space. Most likely this discrepancy is due to the difference in precision between existing event generators and NNLO calculations for dilepton top-pair final states.

    hep-phhep-exPRL(2019)·93 citations
16. 16*

    Narrow exotic hadrons in the heavy quark limit of QCD

    Yiming Cai🇺🇸 · Thomas Cohen🇺🇸

    This paper focuses on tetraquarks containing two heavy quarks in the formal limit where the heavy quark masses are taken to be arbitrarily large. There are well-established model-independent arguments for the existence of deeply bound exotic $\bar{q}{\bar{q}}^{\prime }QQ$ tetraquark in the formal limit of arbitrarily large heavy quark masses. However, these previous arguments did not address the question whether tetraquark states exist close to the threshold for breaking up into two heavy mesons. Such states are not stable under strong interactions---they can emit pions and decay to lower-lying tetraquark states. This raises the issue of whether the nature of the heavy quark limit requires such states to exist as resonances that are narrow. Here we present a model-independent argument that establishes the existence of parametrically narrow tetraquark states. The argument here is based on Born-Oppenheimer and semi-classical considerations. The results derived here are only valid in a formal limit that is well outside the regime occurring for charm quarks in nature. However the analysis may give some insight in the experimentally observed narrow near-threshold tetraquark states containing a heavy quark and antiquark.

    hep-phnucl-thEPJA(2019)·7 citations
17. 17*

    Detecting Dark Matter with Neutron Star Spectroscopy

    Daniel A. Camargo🇧🇷 · Farinaldo S. Queiroz🇧🇷 · Riccardo Sturani🇧🇷

    The presence of dark matter has been ascertained through a wealth of astrophysical and cosmological phenomena and its nature is a central puzzle in modern science. Elementary particles stand as the most compelling explanation. They have been intensively searched for at underground laboratories looking for an energy recoil signal and at telescopes sifting for excess events in gamma-ray or cosmic-ray observations. In this work, we investigate a detection method based on spectroscopy measurements of neutron stars. We outline the luminosity and age of neutrons stars whose dark matter scattering off neutrons can heat neutron stars up to a measurable level. We show that in this case neutron star spectroscopy could constitute the best probe for dark matter particles over a wide masses and interactions strength.

    hep-phJCAP(2019)·71 citations
18. 18*

    Multi-particle potentials from light-like Wilson lines in quark-gluon plasmas: a generalized relation of in-medium splitting rates to jet-quenching parameters $\hat{q}$

    Peter Arnold🇺🇸

    A powerful historical insight about the theory of in-medium showering in QCD backgrounds was that splitting rates can be related to a parameter $\hat{q}$ that characterizes the rate of transverse-momentum kicks to a high-energy particle from the medium. Another powerful insight was that $\hat{q}$ can be defined (with caveats) even when the medium is strongly coupled, using long, narrow Wilson loops whose two long edges are light-like Wilson lines. The medium effects for the original calculations of in-medium splitting rates can be formulated in terms of 3-body imaginary-valued `potentials' that are defined with three long, light-like Wilson lines. Corrections due to overlap of two consecutive splittings can be calculated using similarly defined 4-body potentials. I give a simple argument for how such $N$-body potentials can be determined in the appropriate limit just from knowledge of the values of $\hat{q}$ for different color representations. For $N>3$, the $N$-body potentials have non-trivial color structure, which will complicate calculations of overlap corrections outside of the large-$N_c$ or soft bremsstrahlung limits.

    hep-phnucl-thPRD(2019)·12 citations
19. 19*

    A Two Higgs Doublet Model for Dark Matter and Neutrino Masses

    Daniel A. Camargo🇧🇷 · Miguel D. Campos🇬🇧 · Téssio B. de Melo🇧🇷 · Farinaldo S. Queiroz🇧🇷

    Motivated by the interesting features of Two Higgs Doublet Models (2HDM) we present a 2HDM extension where the stability of dark matter, neutrino masses and the absence of flavor changing interactions are explained by promoting baryon and lepton number to gauge symmetries. Neutrino masses are addressed within the usual type I seesaw mechanism. A vector-like fermion acts as dark matter and it interacts with Standard Model particles via the kinetic and mass mixings between the neutral gauge bosons. We compute the relevant observables such as the dark matter relic density and spin-independent scattering cross section to outline the region of parameter space that obeys current and projected limits from collider and direct detection experiments via thermal and non-thermal dark matter production.

    hep-phPLB(2019)·42 citations
20. 20*

    $\lambda {\varphi }^4$ Theory II: The Broken Phase Beyond NNNN(NNNN)LO

    Marco Serone🇮🇹 · Gabriele Spada🇫🇷 · Giovanni Villadoro🇮🇹

    We extend the study of the two-dimensional euclidean ${\varphi }^4$ theory initiated in ref. [1] to the ${\mathbb{Z}}_2$ broken phase. In particular, we compute in perturbation theory up to N${}^4$LO in the quartic coupling the vacuum energy, the vacuum expectation value of $\varphi$ and the mass gap of the theory. We determine the large order behavior of the perturbative series by finding the leading order finite action complex instanton configuration in the ${\mathbb{Z}}_2$ broken phase. Using an appropriate conformal mapping, we then Borel resum the perturbative series. Interestingly enough, the truncated perturbative series for the vacuum energy and the vacuum expectation value of the field is reliable up to the critical coupling where a second order phase transition occurs, and breaks down around the transition for the mass gap. We compute the vacuum energy using also an alternative perturbative series, dubbed exact perturbation theory, that allows us to effectively reach N${}^8$LO in the quartic coupling. In this way we can access the strong coupling region of the ${\mathbb{Z}}_2$ broken phase and test Chang duality by comparing the vacuum energies computed in three different descriptions of the same physical system. This result can also be considered as a confirmation of the Borel summability of the theory. Our results are in very good agreement (and with comparable or better precision) with those obtained by Hamiltonian truncation methods. We also discuss some subtleties related to the physical interpretation of the mass gap and provide evidence that the kink mass can be obtained by analytic continuation from the unbroken to the broken phase.

    ↳ hep-thcond-mat.stat-mechhep-lathep-phJHEP(2019)·44 citations
21. 21*

    Moduli Stabilization and Inflation in Type IIB/F-theory

    Ignatios Antoniadis🇫🇷 · Yifan Chen🇫🇷 · George K. Leontaris🇬🇷

    In the first part of this talk, a short overview of the ongoing debate on the existence of de Sitter vacua in string theory is presented. In the second part, the moduli stabilisation and inflation are discussed in the context of type IIB/F-theory. Considering a configuration of three intersecting $D7$ branes with fluxes, it is shown that higher loop effects inducing logarithmic corrections to the Kähler potential can stabilise the Kähler moduli in a de Sitter Vacuum. When a new Fayet-Iliopoulos term is included, it is also possible to generate the required number of e-foldings and satisfy the conditions for slow-roll inflation.

    ↳ hep-thgr-qchep-phPoS(2019)·13 citations
22. 22*

    Reweighting Lefschetz Thimbles

    Stefan Bluecher🇩🇪 · Jan M. Pawlowski🇩🇪 · Manuel Scherzer🇩🇪 · Mike Schlosser🇩🇪 · Ion-Olimpiu Stamatescu🇩🇪 · Sebastian Syrkowski🇩🇪 · Felix P.G. Ziegler🇩🇪

    We present a novel reweighting technique to calculate the relative weights in the Lefschetz thimble decomposition of a path integral. Our method is put to work using a $U(1)$ one-link model providing for a suitable testing ground and sharing many features with realistic gauge theories with fermions at finite density. We discuss prospects and future challenges to our method.

    ↳ hep-lathep-phhep-thPoS(2019)·1 citation
23. 23*

    BFKL Eigenvalue and Maximal Alternation of Harmonic Sums

    Alex Prygarin🇮🇱

    We analyze the known results for the eigenvalue of the Balitsky-Fadin-Kuraev-Lipatov (BFKL) equation in the perturbative regime using the analytic continuation of harmonic sums from even positive arguments to the complex plane. The resulting meromorphic functions have poles at negative integer values of the argument. The typical classification of harmonic sums is determined by two major parameters: $a)$ the \textit{weight} - a sum of inverse powers of the summation indices; $b)$ the \textit{depth} - a number of nested summations. We introduce the third parameter: the \textit{alternation} - a number of nested sign-alternating summations in a given harmonic sum. We claim that the maximal alternation of the nested summation in the functions building the BFKL eigenvalue is preserved from loop to loop in the perturbative expansion. The BFKL equation is formulated for arbitrary color configuration of the propagating states in the $t$-channel. Based on known results one can state that color adjoint BFKL eigenvalue be can written using only harmonic sums with positive indices, maximal alternation zero, and at most depth one, whereas the singlet BFKL eigenvalue is constructed of harmonic sums with maximal sign alternation being equal one. We also note that for maximal alternation being equal unity the harmonic sums can be expressed through alternation zero harmonic sums with half-shifted arguments.

    ↳ hep-thhep-phNPB(2019)·7 citations
24. 24*

    Thermal-FIST: A package for heavy-ion collisions and hadronic equation of state

    Volodymyr Vovchenko🇩🇪 · Horst Stoecker🇩🇪

    Thermal-FIST (Thermal, Fast and Interactive Statistical Toolkit) is a C++ package designed for a convenient general-purpose physics analysis within the family of hadron resonance gas (HRG) models. This mainly includes the statistical analysis of particle production in heavy-ion collisions and the phenomenology of hadronic equation of state. Notable features include fluctuations and correlations of conserved charges, effects of probabilistic decay, chemical non-equilibrium, and inclusion of van der Waals hadronic interactions. Calculations are possible within the grand canonical ensemble, the canonical ensemble, as well as in mixed-canonical ensembles combining the canonical treatment of certain conserved charges with the grand-canonical treatment of other conserved charges. The package contains a fast thermal event generator, which generates particle yields in accordance with the HRG chemistry, and particle momenta based on the Blast Wave model. A distinct feature of this package is the presence of the graphical user interface frontend -- QtThermalFIST -- which is designed for fast and convenient general-purpose HRG model applications.

    ↳ nucl-thhep-phnucl-exComput.Phys.Commun.(2019)·221 citations
25. 25*

    nEoS: Neutron Star Equation of State from hadron physics alone

    Eva Lope Oter🇪🇸 · Andreas Windisch🇺🇸 · Felipe J. Llanes-Estrada🇪🇸 · Mark Alford🇺🇸

    We contribute a publicly available set of tables and code to provide Equations of State (EoS) for matter at neutron star densities. Our EoSes are constrained only by input from hadron physics and fundamental principles, without feedback from neutron star observations, and so without relying on General Relativity. They can therefore be used to test General Relativity itself, as well as modified gravity theories, with neutron star observables, without logical circularity. We have adapted state of the art results from NN chiral potentials for the low--density limit, pQCD results for the asymptotically high-density EoS, and use monotonicity and causality as the only restrictions for intermediate densities, for the EoS sets to remain as model-independent as is feasible today.

    ↳ gr-qcastro-ph.HEhep-phnucl-thJ.Phys.G(2019)·36 citations
26. 26*

    LHC analysis-specific datasets with Generative Adversarial Networks

    Bobak Hashemi🇺🇸 · Nick Amin🇺🇸 · Kaustuv Datta🇨🇭 · Dominick Olivito🇺🇸 · Maurizio Pierini🇨🇭

    Using generative adversarial networks (GANs), we investigate the possibility of creating large amounts of analysis-specific simulated LHC events at limited computing cost. This kind of generative model is analysis specific in the sense that it directly generates the high-level features used in the last stage of a given physics analyses, learning the N-dimensional distribution of relevant features in the context of a specific analysis selection. We apply this idea to the generation of muon four-momenta in $Z\to \mu \mu$ events at the LHC. We highlight how use-case specific issues emerge when the distributions of the considered quantities exhibit particular features. We show how substantial performance improvements and convergence speed-up can be obtained by including regression terms in the loss function of the generator. We develop an objective criterion to assess the geenrator performance in a quantitative way. With further development, a generalization of this approach could substantially reduce the needed amount of centrally produced fully simulated events in large particle physics experiments.

    ↳ hep-excs.LGhep-ph125 citations
27. 27*

    Highlights from the Compact Muon Solenoid (CMS) Experiment

    Saranya Samik Ghosh (on behalf of the CMS Collaboration)🇩🇪

    The highlights of the recent activities and physics results leading up to the summer of 2018 from the Compact Muon Solenoid (CMS) experiment at the CERN Large Hadron Collider (LHC) are presented here. The CMS experiment has a very wide-ranging physics program, and only a very limited subset of the physics analyses being performed at CMS are discussed here, consisting of several important results from the analysis of proton-proton collision data at center-of-mass energy of 13 TeV. These include important analyses of Higgs boson physics, with the highlight being the first observation of the $\mathrm{t}\bar{\mathrm{t}}\mathrm{H}$ production of the Higgs boson, along with analyses pertaining to precision standard model measurements, top quark physics, with the single top production cross-section measurement, and flavor physics, with the important observation of ${\chi }_b$(3P) states. Additionally, important searches for physics beyond the standard model are also presented.

    ↳ hep-exhep-phUniverse(2019)·8 citations
28. 28*

    Spectral representation of lattice gluon and ghost propagators at zero temperature

    David Dudal🇧🇪 · Orlando Oliveira🇵🇹 · Martin Roelfs🇧🇪 · Paulo Silva🇵🇹

    We consider the analytic continuation of Euclidean propagator data obtained from 4D simulations to Minkowski space. In order to perform this continuation, the common approach is to first extract the Källén-Lehmann spectral density of the field. Once this is known, it can be extended to Minkowski space to yield the Minkowski propagator. However, obtaining the Källén-Lehmann spectral density from propagator data is a well known ill-posed numerical problem. To regularize this problem we implement an appropriate version of Tikhonov regularization supplemented with the Morozov discrepancy principle. We will then apply this to various toy model data to demonstrate the conditions of validity for this method, and finally to zero temperature gluon and ghost lattice QCD data. We carefully explain how to deal with the IR singularity of the massless ghost propagator. We also uncover the numerically different performance when using two ---mathematically equivalent--- versions of the Källén-Lehmann spectral integral.

    ↳ hep-lathep-phhep-thNPB(2020)·60 citations
29. 29*

    Reconstructing parton distribution functions from Ioffe time data: from Bayesian methods to Neural Networks

    Joseph Karpie🇺🇸 · Kostas Orginos🇺🇸 · Alexander Rothkopf🇳🇴 · Savvas Zafeiropoulos🇩🇪

    The computation of the parton distribution functions (PDF) or distribution amplitudes (DA) of hadrons from first principles lattice QCD constitutes a central open problem. In this study, we present and evaluate the efficiency of a selection of methods for inverse problems to reconstruct the full $x$-dependence of PDFs. Our starting point are the so called Ioffe time PDFs, which are accessible from Euclidean time calculations in conjunction with a matching procedure. Using realistic mock data tests, we find that the ill-posed incomplete Fourier transform underlying the reconstruction requires careful regularization, for which both the Bayesian approach as well as neural networks are efficient and flexible choices.

    ↳ hep-lathep-phnucl-thJHEP(2019)·152 citations
30. 30*

    Siberian snake-like behavior for an orbital polarization of a beam of twisted (vortex) electrons

    Alexander J. Silenko🇷🇺 · Oleg V. Teryaev🇷🇺

    The orbital polarization of twisted electrons carrying an intrinsic orbital angular momentum is not influenced by field perturbations in arbitrary magnetic fields. This property means an existence of the Siberian snake-like behavior for an orbital polarization of a beam of twisted electrons in cyclotrons with the main magnetic field and magnetic focusing. As a result, the acceleration of twisted electron beams in cyclotrons necessary for their applications in high-energy-physics experiments considerably simplifies.

    ↳ physics.class-phhep-phPhys.Part.Nucl.Lett.(2019)·16 citations
31. 31*

    Calculation of Nucleon Electric Dipole Moments Induced by Quark Chromo-Electric Dipole Moments and the QCD $\theta$-term

    S. Syritsyn🇺🇸 · T. Izubuchi🇺🇸 · H. Ohki🇺🇸

    Electric dipole moments (EDMs) of nucleons and nuclei, which are sought as evidence of CP violation, require lattice calculations to connect constraints from experiments to limits on the strong CP violation within QCD or CP violation introduced by new physics from beyond the standard model. Nucleon EDM calculations on a lattice are notoriously hard due to large statistical noise, chiral symmetry violating effects, and potential mixing of the EDM and the anomalous magnetic moment of the nucleon. In this report, details of ongoing lattice calculations of proton and neutron EDMs induced by the QCD $\theta$-term and the quark chromo-EDM, the lowest-dimension effective CP-violating quark-gluon interaction are presented. Our calculation employs chiral-symmetric fermion discretization. An assessment of feasibility of nucleon EDM calculations at the physical point is discussed.

    ↳ hep-lathep-phnucl-thPoS(2019)·18 citations
32. 32*

    Using Circular Polarisation to Test the Composition and Dynamics of Astrophysical Particle Accelerators

    Céline Boehm🇦🇺 · Céline Degrande🇧🇪 · Jakub Scholtz🇬🇧 · Aaron C. Vincent🇨🇦

    We investigate the production of circularly polarised X and gamma-ray signals in cosmic accelerators such as supernova remnants and AGN jets. Proton-proton and proton-photon collisions within these sites produce a charge asymmetry in the distribution of mesons and muons that eventually leads to a net circular polarisation signal as these particles decay radiatively. We find that the fraction of circular polarisation thus produced is at the level of $5\times 10^{-4}$, regardless of the exact beam spectrum, as long as it is made predominantly of protons. While this fraction is very small, the detection of circular polarisation signals in conjunction with high-energy neutrinos would provide an unambiguous signature of the presence of high-energy protons in cosmic accelerators. In Supernovae shocks in particular, this would indicate the presence of relativistic protons hitting stationary protons and/or low-energy photons in the intergalactic or interstellar medium.

    ↳ astro-ph.HEhep-phPRD(2020)·5 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.