Thu·Feb 6, 2020Thursday·February 6, 2020

1. 01*

   Medium-induced gluon radiation with full resummation of multiple scatterings for realistic parton-medium interactions

   Carlota Andres🇺🇸 · Liliana Apolinário🇵🇹 · Fabio Dominguez🇪🇸

   The new precision era of jet quenching observables at both RHIC and the LHC calls for an improved and more precise description of in-medium gluon emissions. The development of new theoretical tools and analytical calculations to tackle this challenge has been hampered by the inability to include the effects of multiple scatterings with the medium using a realistic model for the parton-medium interactions. In this paper, we show how the analytical expressions for the full in-medium spectrum, including the resummation of all multiple scatterings, can be written in a form where the numerical evaluation can be easily performed without the need of the usually employed harmonic or single hard approximations. We present the transverse momentum and energy-dependent medium-induced gluon emission distributions for known realistic interaction models to illustrate how our framework can be applied beyond the limited kinematic regions of previous calculations.

   hep-phnucl-thJHEP(2020)·86 citations
2. 02*

   Towards B -> X_s gamma at the NNLO in QCD without interpolation in m_c

   M. Misiak🇵🇱 · A. Rehman🇩🇪 · M. Steinhauser🇩🇪

   Strengthening constraints on new physics from the B -> X_s gamma branching ratio requires improving accuracy in the measurements and the Standard Model predictions. To match the expected Belle-II accuracy, Next-to-Next-to-Leading Order (NNLO) QCD corrections must be calculated without the so-far employed interpolation in the charm-quark mass m_c. In the process of evaluating such corrections at the physical value of m_c, we have finalized the part coming from diagrams with closed fermion loops on the gluon lines that contribute to the interference of the current-current and photonic dipole operators. We confirm several published results for corrections of this type, and supplement them with a previously uncalculated piece. Taking into account the recently improved estimates of non-perturbative contributions, we find B_{s gamma} = (3.40 \pm 0.17) * 10^{-4} and R_gamma = B_{(s+d) gamma}/B_{c l nu} = (3.35 \pm 0.16) * 10^{-3} for E_gamma > 1.6 GeV in the decaying meson rest frame.

   hep-phJHEP(2020)·202 citations
3. 03*

   Neutrino Oscillations at low energy long baseline experiments in the presence of nonstandard interactions and parameter degeneracy

   Osamu Yasuda🇯🇵

   We discuss the analytical expression of the oscillation probabilities at low energy long baseline experiments, such as T2HK and T2HKK in the presence of nonstandard interactions (NSIs). We show that these experiments are advantageous to explore the NSI parameters (${ϵ}_D$, ${ϵ}_N$), which were suggested to be nonvanishing to account for the discrepancy between the solar neutrino and KamLAND data. We also show that, when the NSI parameters are small, parameter degeneracy in the CP phase $\delta$, ${ϵ}_D$ and ${ϵ}_N$ can be resolved by combining data of the T2HK and T2HKK experiments.

   hep-phPTEP(2020)·7 citations
4. 04*

   QCD factorization and universality of jet cross sections in heavy-ion collisions

   Jian-Wei Qiu🇺🇸 · Felix Ringer🇺🇸 · Nobuo Sato🇺🇸 · Pia Zurita🇩🇪

   We review a recently proposed phenomenological framework to establish the notions of QCD factorization and universality of jet cross sections in the heavy-ion environment. First results of a global analysis of the nuclear modification factor of inclusive jets are presented where we extract medium modified jet functions using a Monte Carlo sampling approach. We observe that gluon jets are significantly more suppressed than quark jets. In addition, we study the jet radius dependence of the inclusive jet cross section in heavy-ion collisions and comment on a recent measurement from CMS. By considering for example jet substructure observables it will be possible to test the universality of the extracted medium jet functions. We thus expect that the presented results will eventually allow for extractions of medium properties with a reduced model bias.

   hep-phnucl-exnucl-thNPA(2021)·7 citations
5. 05*

   Constraining the Higgs valence contribution in the proton

   Simon Fernbach🇦🇹 · Lukas Lechner🇦🇹 · Axel Maas🇦🇹 · Simon Plätzer🇦🇹 · Robert Schöfbeck🇦🇹

   Non-perturbative gauge-invariance under the strong and the weak interactions dictates that the proton contains a non-vanishing valence contribution from the Higgs particle. By introducing an additional parton distribution function (PDF), we investigate the experimental consequences of this prediction. The Herwig 7 event generator and a parametrized CMS detector simulation are used to obtain predictions for a scenario amounting to the LHC Run II data set. We use those to assess the impact of the Higgs PDF on the pp->ttbar process in the single lepton final state. Comparing to nominal simulation we derive expected limits as a function of the shape of the valence Higgs PDF. We also investigate the process pp->ttZ at the parton level to add further constraints.

   hep-phhep-exPRD(2020)·14 citations
6. 06*

   Twisted particle collisions: a new tool for spin physics

   Igor P. Ivanov🇵🇹 · Nikolai Korchagin🇨🇳 · Alexandr Pimikov🇨🇳 · Pengming Zhang🇨🇳

   Collisions of twisted particles --- that is, non-plane-wave states of photons, electrons, or any other particle, equipped with a non-zero orbital angular momentum (OAM) with respect to its propagation direction --- offer novel ways to probe particle structure and interactions. In the recent paper \cite{Ivanov:2019vxe}, we argued that resonance production in twisted photon collisions or twisted $e^{+}{e}^{-}$ annihilation gives access to parity- and spin-sensitive observables in inclusive cross sections, even when the initial particles are unpolarized. Here, we explore these features in detail, providing a qualitative picture and illustrating it with numerical examples. We show how one can detect parity-violating effects in collisions of unpolarized twisted photons and how one can produce almost $100\%$ polarized vector mesons in unpolarized twisted $e^{+}{e}^{-}$ annihilation. These examples highlight the unprecedented level of control over polarization offered by twisted particles, impossible in the usual plane wave collisions.

   hep-phPRD(2020)·20 citations
7. 07*

   Fundamental physics tests using the propagation of GNSS signals

   Bruno Bertrand🇧🇪 · Pascale Defraigne (Royal Observatory of Belgium)🇧🇪

   This paper introduces new tests of fundamental physics by means of the analysis of disturbances on the GNSS signal propagation. We show how the GNSS signals are sensitive to a space variation of the fine structure constant $\alpha$ in a generic framework of effective scalar field theories beyond the Standard Model. This effective variation may originate from the crossing of the RF signals with dark matter clumps and/or solitonic structures. At the macroscopic scale, the subsequent disturbances are equivalent to those which occur during the propagation in an inhomogeneous medium. We thus propose an interpretation of the "measure" of the vacuum permeability as a test of fundamental physics. We show the relevance of our approach by a first quantification of the expected signature in a simple model of a variation of $\alpha$ according to a planar geometry. We use a test-bed model of domain walls for that purpose and focus on the measurable time delay in the GNSS signal carrier.

   hep-phphysics.space-phAdv.Space Res.(2020)·2 citations
8. 08*

   PMC${}_{\infty }$: Infinite-Order Scale-Setting using the Principle of Maximum Conformality, A Remarkably Efficient Method for Eliminating Renormalization Scale Ambiguities for Perturbative QCD

   Leonardo Di Giustino🇮🇹 · Stanley J. Brodsky🇺🇸 · Sheng-Quan Wang🇨🇳 · Xing-Gang Wu🇨🇳

   We identify a property of renormalizable SU(N)/U(1) gauge theories, the intrinsic Conformality ($iCF$), which underlies the scale invariance of physical observables and leads to a remarkably efficient method to solve the conventional renormalization scale ambiguity at every order in pQCD: the PMC${}_{\infty }$. This new method reflects the underlying conformal properties displayed by pQCD at NNLO, eliminates the scheme dependence of pQCD predictions and is consistent with the general properties of the PMC (Principle of Maximum Conformality). We introduce a new method to identify conformal and $\beta$-terms which can be applied either to numerical or to theoretical calculations. We illustrate the PMC${}_{\infty }$ for the thrust and C-parameter distributions in $e^{+}{e}^{-}$ annihilation and then we show how to apply this new method to general observables in QCD. We point out how the implementation of the PMC${}_{\infty }$ can significantly improve the precision of pQCD predictions; its implementation in multi-loop analysis also simplifies the calculation of higher orders corrections in a general renormalizable gauge theory.

   hep-phhep-thPRD(2020)·27 citations
9. 09*

   Light-by-Light Scattering and Spacetime Noncommutativity

   Raul Horvat🇭🇷 · Dusko Latas🇷🇸 · Josip Trampetic🇭🇷 · Jiangyang You🇭🇷

   The aim of this article is to explore a potential usability of a photon-photon self-interaction from the noncommutative quantum electrodynamics (NCQED) in the case of light-by-light scattering ($\gamma \gamma \to \gamma \gamma$) in ultraperipheral Pb+Pb collisions, a reaction measured recently by ATLAS and planned for future experiments in hadron-hadron colliders. We compute the total cross section from both, the full one-loop standard model (SM) and the tree-level NCQED amplitudes, in the equivalent photon approximation with impact parameters, for various noncommutative scales, ${\mathrm{\Lambda }}_{\mathrm{NC}}$, and incoming nuclear spin-energy combinations. We find that NCQED contribution to the cross section has considerable increase at diphoton invariant mass range higher than ${\mathrm{\Lambda }}_{\mathrm{NC}}$, while the SM contribution is strongly suppressed in such region. Our results show that the current ATLAS $\sqrt{{\mathrm{s}}_{\mathrm{NN}}}=5.02$ TeV experiment can only probe ${\mathrm{\Lambda }}_{\mathrm{NC}}<100$ GeV region. On the other hand, future hadron-hadron collider proposals could have the potential to extend to ${\mathrm{\Lambda }}_{\mathrm{NC}}\lesssim 300$ GeV region, making the performance of $\mathrm{Pb}+\mathrm{Pb}(\gamma \gamma )\to \mathrm{Pb}+\mathrm{Pb}\gamma \gamma$ scattering on testing space-time noncommutativity close to that of the previously proposed photon-photon mode of linear electron-positron collider.

   hep-phhep-thPRD(2020)·24 citations
10. 10*

    Role of IR-Improvement in Precision LHC/FCC Physics and in Quantum Gravity

    B.F.L. Ward (1)🇺🇸 · S. Jadach (2)🇵🇱 · W. Placzek (3)🇵🇱 · M. Skrzypek (2)🇵🇱 · Z. A. Was (2)🇵🇱 · S. A. Yost (4) ((1) Baylor University, Waco, TX, USA, (2) Institute of Nuclear Physics, Krakow, PL, (3) Jagiellonian University, Krakow, PL, (4) The Citadel, Charleston, SC, USA)🇺🇸

    IR-improvement based on amplitude-level resummation allows one to control unintegrable results in quantum field theory with arbitrary precision in principle. We illustrate such resummation in specific examples in precision LHC and FCC physics and in quantum gravity.

    hep-phPoS(2019)·2 citations
11. 11*

    Black hole production at lepton colliders

    Hang Qi🇺🇸 · Roberto Onofrio🇮🇹

    Production of black holes has been discussed in a variety of extensions of the Standard Model, and related bounds have been established from data taken at the Large Hadron Collider. We show that, if the Higgs particle has a fully gravitational content via the equivalence principle, enhanced cross-sections of black holes at colliders should be expected within the Standard Model itself. The case of black hole production by precision measurements at electron colliders is discussed. The Coulomb repulsion strongly suppresses the related cross-section with respect to the one based on the hoop conjecture, making the possible production of black holes still unfeasible with current beam technology. At the same time, this suggests the reanalysis of the bounds, based on the hoop conjecture, already determined in hadronic collisions for extra-dimensional models.

    hep-phgr-qcPLB(2019)·0 citations
12. 12*

    Five Texture Zeros for Dirac Neutrino Mass Matrices

    Richard H. Benavides🇨🇴 · Yithsbey Giraldo🇨🇴 · Luis Muñoz🇨🇴 · William A. Ponce🇨🇴 · Eduardo Rojas🇨🇴

    In this work we propose new five textures zeros for the mass matrices in the lepton sector in order to predict values for the neutrino masses. In our approach we go beyond the Standard Model by assuming Dirac masses for the neutrinos, feature which allows us to make a theoretical prediction for the lightest neutrino mass in the normal ordering. The textures analyzed have enough free parameters to adjust the $V_{\text{PMNS}}$ mixing matrix including the CP-violating phase, the neutrino mass squared differences $\delta m_{21}^2,\delta m_{31}^2$, and the three charged lepton masses. In order to have reliable results two different approaches are used: the first one is based on a least-squares analysis to fit the lepton masses and the mixing parameters to their corresponding experimental values, for this case the best fit for the lightest neutrino mass is $(3.9{\pm }_{0.8}^{0.6})\times 10^{-3}$ eV.; the second approach is just algebraic, based on the weak basis transformation method, in this case the lightest neutrino mass consistent with the experimental values and the restrictions coming from the five texture zeros of the mass matrices is equal to $(3.5\pm 0.9)\times 10^{-3}$ eV.

    hep-phJ.Phys.G(2020)·10 citations
13. 13*

    $W^{+}{W}^{-}$ production at the LHC: NLO QCD corrections to the loop-induced gluon fusion channel

    Massimiliano Grazzini🇨🇭 · Stefan Kallweit🇮🇹 · Marius Wiesemann🇩🇪 · Jeong Yeon Yook🇨🇭

    We compute the NLO QCD corrections to the loop-induced gluon fusion contribution in $W^{+}{W}^{-}$ production at the LHC. We consider the full leptonic process $pp\to {\ell }^{+}{\ell }^{\prime -}{\nu }_{\ell }{\bar{\nu }}_{{\ell }^{\prime }}+X$, by including resonant and non-resonant diagrams, spin correlations and off-shell effects. Quark-gluon partonic channels are included for the first time in the calculation, and our results are combined with NNLO predictions to the quark annihilation channel at the fully differential level. The computed corrections, which are formally of $\mathcal{O}({\alpha }_{\mathrm{S}}^3)$, increase the NNLO cross section by only about 2%, but have an impact on the shapes of kinematical distributions, in part due to the jet veto, which is usually applied to reduce the top-quark background. Our results, supplemented with NLO EW effects, provide the most advanced fixed-order predictions available to date for this process, and are compared with differential ATLAS data at $\sqrt{s}=$ 13 TeV.

    hep-phPLB(2020)·37 citations
14. 14*

    Improving the Drell--Yan probe of small x partons at the LHC via an azimuthal angle cut

    M. Kendi Yamasaki🇧🇷 · Emmanuel G. de Oliveira🇧🇷

    Predictions for Drell--Yan lepton pair production at low dilepton mass and small x at the LHC usually have a large scale dependence. This can be decreased by determining an "optimal factorization scale". In this paper, we reduce this scale by imposing a cutoff in azimuthal angle between the transverse momentum of the leptons, properly taking into account Sudakov effects. This allows one to probe the parton distributions at smaller scales eliminating most of the current theoretical uncertainty.

    hep-phEPJC(2020)·0 citations
15. 15*

    Fermion masses and mixing in modular A4 Symmetry

    Mohamed Abbas🇸🇦

    We consider a flavor model based on A4 modular group to account for both lepton and quark parameters (masses and mixing). The inverse seesaw mechanism is considered to produce the light neutrino masses. Lepton masses and mixing are obtained in terms of Yukawa coupling ratios and values of the modulus {\tau} nearby some fixed points for inverted neutrino mass hierarchy. The quark masses and mixing are arisen at the same {\tau} values used in inverted neutrino mass hierarchy and are in agreements with the recent data.

    hep-phPRD(2021)·53 citations
16. 16*

    Superheavy dark matter in $R+R^2$ cosmology with conformal anomaly

    E. V. Arbuzova🇷🇺 · A. D. Dolgov🇷🇺 · R. S. Singh🇷🇺

    Cosmological evolution and particle creation in $R^2$-modified gravity are considered for the case of the dominant decay of the scalaron into a pair of gauge bosons due to conformal anomaly. It is shown that in the process of thermalization superheavy dark matter with the coupling strength typical for the GUT SUSY can be created. Such dark matter would have the proper cosmological density if the particle mass is close to $10^{12}$ GeV.

    hep-phastro-ph.COEPJC(2020)·15 citations
17. 17*

    Primer on ILC Physics and SiD Software Tools

    C.T. Potter🇺🇸

    We first outline the Standard Model (SM) of particle physics, particle production and decay, and the expected signal and background at a Higgs factory like the International Linear Collider (ILC). We then introduce high energy colliders and collider detectors, and briefly detail the ILC and the Silicon Detector (SiD), one of the two detectors proposed for the ILC. Next we review the available software tools for ILC event generation, SiD detector simulation, and event reconstruction. Finally we suggest open avenues in research for detector optimization and physics analysis. The pedagogical level is suitable for advanced undergraduate and beginning graduate students in physics and research scientists in related fields.

    hep-phhep-exphysics.comp-phphysics.data-an4 citations
18. 18*

    Constraints on long range force from perihelion precession of planets in a gauged $L_e-L_{\mu ,\tau }$ scenario

    Tanmay Kumar Poddar🇮🇳 · Subhendra Mohanty🇮🇳 · Soumya Jana🇨🇭

    The standard model particles can be gauged in an anomaly free way by three possible gauge symmetries namely $L_e-L_{\mu }$, $L_e-L_{\tau }$, and $L_{\mu }-L_{\tau }$. Of these, $L_e-L_{\mu }$ and $L_e-L_{\tau }$ forces can mediate between the Sun and the planets and change the perihelion precession of planetary orbits. It is well known that a deviation from the $1/r^2$ Newtonian force can give rise to a perihelion advancement in the planetary orbit, for instance, as in the well known case of Einstein's gravity which was tested from the observation of the perihelion advancement of the Mercury. We consider the long range Yukawa potential which arises between the Sun and the planets if the mass of the gauge boson is $M_{Z^{\prime }}\le \mathcal{O}(10^{-19})\mathrm{eV}$. We derive the formula of perihelion advancement for Yukawa type fifth force due to the mediation of such $U(1{)}_{L_e-L_{\mu ,\tau }}$ gauge bosons. The perihelion advancement for Yukawa potential is proportional to the square of the semi major axis of the orbit for small $M_{Z^{\prime }}$, unlike GR, where it is largest for the nearest planet. However for higher values of $M_{Z^{\prime }}$, an exponential suppression of the perihelion advancement occurs. We take the observational limits for all planets for which the perihelion advancement is measured and we obtain the upper bound on the gauge boson coupling $g$ for all the planets. The Mars gives the stronger bound on $g$ for the mass range $\le 10^{-19}\mathrm{eV}$ and we obtain the exclusion plot. This mass range of gauge boson can be a possible candidate of fuzzy dark matter whose effect can therefore be observed in the precession measurement of the planetary orbits.

    hep-phastro-ph.EPastro-ph.HEgr-qc+1EPJC(2021)·51 citations
19. 19*

    KKLT without AdS

    Andrei Linde🇺🇸

    According to the KKLT scenario, metastable dS vacua are formed as a result of uplifting of supersymmetric AdS vacua by $\overline{D3}$ branes. I describe an extended version of this scenario where metastable dS vacua appear after an uplift from a state where the potential of the volume modulus in the absence of $\overline{D3}$ branes would be unbounded below. This mechanism may considerably strengthen vacuum stabilization in the early universe.

    ↳ hep-thastro-ph.COgr-qchep-phJHEP(2020)·16 citations
20. 20*

    N=2 PNGB Quintessence Dark Energy

    Keunsu Cheon🇰🇷 · Jungjai Lee🇰🇷

    In this paper we show that a pseudo-Nambu-Goldstone boson (PNGB) quintessence of spontaneous symmetry breaking (SSB) is responsible for an epoch of the late time cosmic acceleration. We suggest that an N=2 PNGB quintessence with SSB can give rise to the fast-roll cosmic acceleration in evolution of the Universe. In the N=2 PNGB quintessence model, the standard slow-roll condition in which the absolute value of the tachyonic mass squared $|m_q^2|$ of this model is much less than the square of the Hubble constant $H^2$, is broken down to the fast-roll condition, $|m_q^2|=O(H^2)$. However, it is shown that the fast-rolling associated with the N=2 PNGB quintessence of SSB can be led to the epoch of the late time cosmic acceleration. Indeed, in our PNGB model, this epoch can be quite long lasting since the mass of the N=2 PNGB quintessence field is extremely small as $m_q\approx 10^{-33}\mathrm{eV}$.

    ↳ gr-qcastro-ph.COhep-phhep-thJ.Korean Phys.Soc.(2021)·2 citations
21. 21*

    Contraction Diagram Analysis in Pion-Kaon Scattering

    Chaitra Kalmahalli Guruswamy🇩🇪 · Ulf-G. Meißner🇩🇪 · Chien-Yeah Seng🇩🇪

    We study the contributions from the connected and disconnected contraction diagrams to the pion-kaon scattering amplitude within the framework of SU$(4|1)$ partially-quenched chiral perturbation theory. Combining this with a finite-volume analysis, we demonstrate that a lattice calculation of the easier computable connected correlation functions is able to provide valuable information of the noisier disconnected correlation functions, and may serve as a theory guidance for the future refinement of the corresponding lattice techniques.

    ↳ hep-lathep-phnucl-thNPB(2020)·5 citations
22. 22*

    Axion and dark photon limits from Crab Nebula high energy gamma-rays

    Xiao-Jun Bi🇨🇳 · Yu Gao🇨🇳 · Junguang Guo🇨🇳 · Nick Houston🇨🇳 · Tianjun Li🇨🇳 · Fangzhou Xu🇨🇳 · Xin Zhang🇨🇳

    The observation of cosmic sub-PeV gamma-rays from the Crab Nebula opens up the possibility of testing cosmic ray photon transparency at the multi-hundred TeV scale. Assuming no deviation from a source gamma-ray emission due to accelerated electron inverse-Compton scattering, higher event energies can extend constraints on the effects of new physics; We consider oscillation between gamma-rays and axions/dark photons, plus attenuation effects from gamma-ray absorption in the case of dark photon dark matter. Combining the recent AS$\gamma$ and HAWC sub-PeV data with earlier MAGIC and HEGRA data, axion-like particles are most constrained in the $10^{-7}-10^{-6}$ eV mass range, where the coupling $g_{a\gamma }$ is constrained to be below $1.8\times 10^{-10}$ GeV${}^{-1}$. In comparison, gamma ray flux attenuation due to oscillation with a dark photon leads to a very weak constraint on the mixing parameter; $ϵ\lesssim$ 0.2 for dark photon mass between $10^{-7}$ and $10^{-6}$ eV. Direct scattering from dark photon dark matter limits $ϵ\lesssim$ 0.01 for masses between $6$ and $400$ eV.

    ↳ astro-ph.HEhep-phPRD(2021)·41 citations
23. 23*

    Higher order cumulants of net baryon-number distributions at non-zero ${\mu }_B$

    Dennis Bollweg🇩🇪 · Frithjof Karsch🇩🇪 · Swagato Mukherjee🇺🇸 · Christian Schmidt🇩🇪

    Using recent results on higher order cumulants of conserved charge fluctuations from lattice QCD, we construct mean, variance, skewness, kurtosis, hyper-skewness and hyper-kurtosis of net-baryon number distributions for small baryon chemical potentials ${\mu }_B$. For the strangeness neutral case (${\mu }_S=0$) at fixed ratio of electric charge to baryon number density ($\frac{n_Q}{n_B}=0.4$), which is appropriate for a comparison with heavy ion collisions, we present results for ${\kappa }_B{\sigma }_B^2$, $S_B{\sigma }_B^3/M_B$, ${\kappa }_B^H{\sigma }_B^4$ and $S_B^H{\sigma }_B^5/M_B$ on the crossover line for the chiral transition, $T_{pc}({\mu }_B)$. Continuum extrapolations for this pseudo-critical transition line have recently been reported by HotQCD up to baryon chemical potentials ${\mu }_B\simeq 300$ MeV [arXiv:1812.08235]. These cumulant ratios are of direct relevance for comparisons with corresponding ratios measured by STAR in the BES-I and II runs at beam energies $\sqrt{s_{NN}}\ge 20$ GeV. In particular, we point out that recent high statistics results on skewness and kurtosis of net-baryon number distributions obtained by STAR at $\sqrt{s_{NN}}=54.4$ GeV put strong constraints on freeze-out parameters and are consistent with predictions from thermal QCD.

    ↳ hep-lathep-phnucl-thNPA(2021)·8 citations
24. 24*

    From Chiral Kinetic Theory To Spin Hydrodynamics

    Shuzhe Shi🇨🇦 · Charles Gale🇨🇦 · Sangyong Jeon🇨🇦

    The total angular momentum is conserved in the evolution of the Quark-Gluon Plasma (QGP) created in heavy-ion collision, and consists of two sectors: the orbital angular momentum (OAM) caused by kinetic motion, and the spin, an intrinsic degree of freedom of quarks and gluons. Microscopic scattering processes allow the conversion between these two components, hence the spin density could eventually have non-trivial influence on the QGP evolution. A hydrodynamic theory, with the spin polarization effect properly taken into account, is required to quantitatively study the polarization rate for observed hadrons, e.g. the $\Lambda$-hyperon. In this work, we start with chiral kinetic theory and construct the spin hydrodynamic framework for a chiral spinor system. We obtain the equations of motion of second-order dissipative relativistic fluid dynamics with non-trivial spin polarization density.

    ↳ nucl-thhep-phNPA(2021)·22 citations
25. 25*

    On the computation of intersection numbers for twisted cocycles

    Stefan Weinzierl🇩🇪

    Intersection numbers of twisted cocycles arise in mathematics in the field of algebraic geometry. Quite recently, they appeared in physics: Intersection numbers of twisted cocycles define a scalar product on the vector space of Feynman integrals. With this application, the practical and efficient computation of intersection numbers of twisted cocycles becomes a topic of interest. An existing algorithm for the computation of intersection numbers of twisted cocycles requires in intermediate steps the introduction of algebraic extensions (for example square roots), although the final result may be expressed without algebraic extensions. In this article I present an improvement of this algorithm, which avoids algebraic extensions.

    ↳ math-phhep-phhep-thmath.AG+1J.Math.Phys.(2021)·81 citations
26. 26*

    First Results on Dark Matter Substructure from Astrometric Weak Lensing

    Cristina Mondino🇺🇸 · Anna-Maria Taki🇺🇸 · Ken Van Tilburg🇺🇸 · Neal Weiner🇺🇸

    Low-mass structures of dark matter (DM) are expected to be entirely devoid of light-emitting regions and baryons. Precisely because of this lack of baryonic feedback, small-scale substructures of the Milky Way are a relatively pristine testing ground for discovering aspects of DM microphysics and primordial fluctuations on subgalactic scales. In this work, we report results from the first search for Galactic DM subhalos with time-domain astrometric weak gravitational lensing. The analysis is based on a matched-filter template of local lensing corrections to the proper motion of stars in the Magellanic Clouds. We describe a data analysis pipeline detailing sample selection, background subtraction, and handling outliers and other systematics. For tentative candidate lenses, we identify a signature based on an anomalous parallax template that can unequivocally confirm the presence of a DM lens, opening up prospects for robust discovery potential with full time-series data. We present our constraints on substructure fraction $f_l\lesssim 5$ at 90% CL (and $f_l\lesssim 2$ at 50% CL) for compact lenses with radii $r_l<1\mathrm{pc}$, with best sensitivity reached for lens masses $M_l$ around $10^7$-$10^8{M}_{\odot }$. Parametric improvements are expected with future astrometric data sets; by end of mission, $Gaia$ could reach $f_l\lesssim 10^{-3}$ for these massive point-like objects, and be sensitive to lighter and/or more extended subhalos for $\mathcal{O}(1)$ substructure fractions.

    ↳ astro-ph.COastro-ph.GAhep-phPRL(2020)·45 citations
27. 27*

    A theoretical approach to study J/$\Psi$ suppression in relativistic heavy ion collisions

    Santosh K. Karn (Department of Physics, School of Basic Sciences and Research, Sharda University)🇮🇳

    With a view to understanding J/$\Psi$ suppression in relativistic heavy ion collisions, we compute the suppression rate within the framework of hydrodynamical evolution model. For this, we consider an ellipsoidal flow and use an ansatz for temperature profile function which accounts for time and the three dimensional space evolution of the quark-gluon plasma. We have calculated the survival probability separately as the function of transverse and longitudinal momentum. We have shown that previous calculations are special cases of this model.

    ↳ nucl-thhep-phOpen J.Microphys.(2020)·0 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.