Thu·May 24, 2018Thursday·May 24, 2018

1. 01*

   The Ridge Effect, Azimuthal Correlations, and other Novel Features of Gluonic String Collisions in High Energy Photon-Mediated Reactions

   Stanisław D. Głazek🇵🇱 · Stanley J. Brodsky🇺🇸 · Alfred S. Goldhaber🇺🇸 · Robert W. Brown🇺🇸

   One of the remarkable features of high-multiplicity hadronic events in proton-proton collisions at the LHC is the fact that the produced particles appear as two "ridges", opposite in azimuthal angle $\varphi$, with approximately flat rapidity distributions. This phenomena can be identified with the inelastic collision of gluonic flux tubes associated with the QCD interactions responsible for quark confinement in hadrons. In this paper we analyze the ridge phenomena when the collision involves a flux tube connecting the quark and antiquark of a high energy real or virtual photon. We discuss gluonic tube string collisions in the context of two examples: electron-proton scattering at a future electron-ion collider or the peripheral scattering of protons accessible at the LHC. A striking prediction of our analysis is that the azimuthal angle of the produced ridges will be correlated with the scattering plane of the electron or proton producing the virtual photon. In the case of $ep\to eX$, the final state $X$ is expected to exhibit maximal multiplicity when the elliptic flow in $X$ is aligned with the electron scattering plane. In the $pp\to ppX$ example, the multiplicity and elliptic flow in $X$ are estimated to exhibit correlated oscillations as functions of the azimuthal angle $\Phi$ between the proton scattering planes. In the minimum-bias event samples, the amplitude of oscillations is expected to be on the order of 2 to 4 percent of the mean values. In the events with highest multiplicity, the oscillations can be three times larger than in the minimum-bias event samples.

   hep-phPRD(2018)·4 citations
2. 02*

   Dynamical spin effects in the holographic light-front wavefunctions of light pseudoscalar mesons

   Mohammad Ahmady🇨🇦 · Chandan Mondal🇨🇳 · Ruben Sandapen🇨🇦

   We quantify the importance of dynamical spin effects in the holographic light-front wavefunctions of the pion, kaon, $\eta$ and ${\eta }^{\prime }$. Using a universal AdS/QCD scale and constituent quark masses, we find that such effects are maximal in the pion where they lead to an excellent simultaneous description of a wide range of data: the decay constant, charge radius, spacelike EM and transition form factors, as well as, after QCD evolution, both the parton distribution function and the parton distribution amplitude data from Fermilab. These dynamical spin effects lead up to a $30\%$ chance of finding the valence quark and antiquark with aligned spins in the pion. The situation is very different for the kaon, where a simultaneous description of the available data (decay constant, radius and spacelike EM form factor) prefer no dynamical spin effects at all. The situation is less clear for the $\eta$ and ${\eta }^{\prime }$: while their radiative decay widths data are consistent with dynamical spin effects only in ${\eta }^{\prime }$, the data on their spacelike transition form factors clearly favor maximal dynamical spin effects in both mesons.

   hep-phPRD(2018)·44 citations
3. 03*

   Control the model sign problem via path optimization method: Monte-Carlo approach to QCD effective model with Polyakov loop

   Kouji Kashiwa🇯🇵 · Yuto Mori🇯🇵 · Akira Ohnishi🇯🇵

   We apply the path optimization method to a QCD effective model with the Polyakov loop at finite density to circumvent the model sign problem. The Polyakov-loop extended Nambu--Jona-Lasinio model is employed as the typical QCD effective model and then the hybrid Monte-Carlo method is used to perform the path integration. To control the sign problem, the path optimization method is used with complexification of temporal gluon fields to modify the integral path in the complex space. We show that the average phase factor is well improved on the modified integral-path compared with that on the original one. This indicates that the complexification of temporal gluon fields may be enough to control the sign problem of QCD in the path optimization method.

   hep-phhep-lathep-thPRD(2019)·41 citations
4. 04*

   Next-to-Leading Order QCD Corrections to Inclusive Heavy-Flavor Production in Polarized Deep-Inelastic Scattering

   Felix Hekhorn🇩🇪 · Marco Stratmann🇩🇪

   We provide a first calculation of the complete next-to-leading order QCD corrections for heavy flavor contributions to the inclusive structure function $g_1$ in longitudinally polarized deep-inelastic scattering. The results are derived with largely analytical methods and retain the full dependence on the heavy quark's mass. We discuss all relevant technical details of the calculation and present numerical results for the heavy quark scaling functions. We perform important crosschecks to verify our results in the known limit of photoproduction and for the unpolarized electroproduction of heavy quarks. We also compare our calculations to the available, partial results in the polarized case, in particular, in the limit of asymptotically large photon virtualities, and analyze the behavior of the scaling functions near threshold. First steps towards phenomenological applications are taken by providing some estimates for inclusive charm production in polarized deep-inelastic scattering at a future electron-ion collider and studying their sensitivity to the polarized gluon distribution. The residual dependence of heavy quark electroproduction on unphysical factorization and renormalization scales and on the heavy quark mass is investigated.

   hep-phPRD(2018)·36 citations
5. 05*

   Discrimination of effective radiative and collisional in-medium energy-loss models by their effects on angular jet structure

   Martin Rohrmoser🇵🇱 · Pol-Bernard Gossiaux🇫🇷 · Thierry Gousset🇫🇷 · Jörg Aichelin🇫🇷

   Energy-loss studies of hard particle probes produced in heavy ion collisions have often been used to get information on the interactions within the medium of a quark-gluon plasma (QGP). However, with the study of in-medium energy-loss of individual particles alone, it remains still ambiguous, whether the occured decrease in particle energy is caused by predominantly radiative or collisional energy-loss mechanisms. Focusing on the in-medium energy-loss of hard jet-partons, we propose additional studies of the angular jet-structure as a means to further constrain the energy-loss mechanisms.

   hep-phActa Phys.Polon.B(2018)·5 citations
6. 06*

   Search for doubly heavy baryon via weak decays

   Run-Hui Li🇨🇳 · Cai-Dian Lu🇨🇳

   Using the factorization approach and taking into account the final state interaction, we calculate the two body non-leptonic decays of doubly heavy baryons. After comparing the semi-leptonic decays and all possible hadronic decay channels, we found some channels with large branching ratios. Taking the detection efficiency into consideration, we suggest ${\Xi }_{cc}^{++}$ as the first search goal and ${\Xi }_{cc}^{++}\to {\Lambda }_c^{+}{K}^{-}{\pi }^{+}{\pi }^{+}$ and ${\Xi }_{cc}^{++}\to {\Xi }_c^{+}{\pi }^{+}$ as the golden discovery channels with ${\Lambda }_c^{+}$ reconstructed by $p{K}^{-}{\pi }^{+}$ and ${\Xi }_c^{+}\to p{K}^{-}{\pi }^{+}$, respectively.

   hep-ph12 citations
7. 07*

   Resonant production of $Z^{\prime }$ and signature of right-handed neutrinos within a 3-3-1 model

   F. F. Freitas🇨🇳 · C. A. de S. Pires🇧🇷 · P. Vasconcelos🇧🇷

   Recent simulation studies indicate that right-handed neutrinos may be discovered at future high luminosity LHC runs as long as a new neutral gauge boson, $Z^{\prime }$, have been discovered first. In this case, when $Z^{\prime }$ is resonantly produced at the LHC it, subsequently, decays into pair of right-handed neutrinos with mass up to TeV scale. Then the decay of these neutrinos leave as signature tri-lepton final states and/or same-sign di-muon and a boost di-boson. The prospect of discovering right-handed neutrinos through this mechanism has been developed within abelian gauge extension of the standard model. In this work we study the processes involved in this discovery mechanism within the framework of the 3-3-1 model.

   hep-phPRD(2018)·8 citations
8. 08*

   Quark mass generation with Schwinger-Dyson equations

   A. C. Aguilar🇧🇷 · M. N. Ferreira🇧🇷

   In this talk, we review some of the current efforts to understand the phenomenon of chiral symmetry breaking and the generation of a dynamical quark mass. To do that, we will use the standard framework of the Schwinger-Dyson equations. The key ingredient in this analysis is the quark-gluon vertex, whose non-transverse part may be determined exactly from the nonlinear Slavnov-Taylor identity that it satisfies. The resulting expressions for the form factors of this vertex involve not only the quark propagator, but also the ghost dressing function and the quark-ghost kernel. Solving the coupled system of integral equations formed by the quark propagator and the four form factors of the scattering kernel, we carry out a detailed study of the impact of the quark gluon vertex on the gap equation and the quark masses generated from it, putting particular emphasis on the contributions directly related with the ghost sector of the theory, and especially the quark-ghost kernel. Particular attention is dedicated on the way that the correct renormalization group behavior of the dynamical quark mass is recovered, and in the extraction of the phenomenological parameters such as the pion decay constant.

   hep-ph1 citation
9. 09*

   Two-loop five-point massless QCD amplitudes within the IBP approach

   Herschel A. Chawdhry🇬🇧 · Matthew A. Lim🇬🇧 · Alexander Mitov🇬🇧

   We solve the integration-by-parts (IBP) identities needed for the computation of any planar two-loop five-point massless amplitude in QCD. We also derive some new results for the most complicated non-planar topology with irreducible numerators of power as high as six. We do this by applying a new strategy for solving the IBP identities which scales better for problems with a large number of scales and/or master integrals. Our results are a proof of principle that the remaining non-planar contributions for all two-loop five-point massless QCD amplitudes can be computed in analytic form.

   hep-phhep-thPRD(2019)·59 citations
10. 10*

    Active and sterile neutrino phenomenology with $A_4$ based minimal extended seesaw

    Pritam Das🇮🇳 · Ananya Mukherjee🇮🇳 · Mrinal Kumar Das🇮🇳

    We study a model of neutrino within the framework of the minimal extended seesaw (MES), which plays an important role in active and sterile neutrino phenomenology in (3+1) scheme. The $A_4$ flavor symmetry is augmented by an additional $Z_4\times Z_3$ symmetry to constraint the Yukawa Lagrangian of the model. We use non-trivial Dirac mass matrix, with broken $\mu -\tau$ symmetry, as the origin of leptonic mixing. Interestingly, such a structure of mixing naturally leads to the non-zero reactor mixing angle ${\theta }_{13}$. Non-degenerate mass structure for right-handed neutrino $M_R$ is considered so that we can further extend our study to Leptogenesis. We have also considered three different cases for sterile neutrino mass, $M_S$ to check the viability of this model, within the allowed $3\sigma$ bound in this MES framework.

    hep-phNPB(2019)·30 citations
11. 11*

    Neutral Current Forward-Backward Asymmetry: from ${\theta }_W$ to PDF Determinations

    Elena Accomando🇬🇧 · Juri Fiaschi🇩🇪 · Francesco Hautmann🇬🇧 · Stefano Moretti🇬🇧

    Measurements of the forward-backward asymmetry in neutral-current Drell-Yan di-lepton production have primarily been used for determinations of the weak mixing angle ${\theta }_W$. We observe that, unlike the case of Run-I of the Large Hadron Collider (LHC Run-I), for the first time at the LHC Run-II the reconstructed forward-backward asymmetry has the capability of placing useful constraints on the determination of the parton distribution functions (PDFs). By examining the statistical and the PDF uncertainties on the reconstructed forward-backward asymmetry, we investigate its potential for disentangling the flavour content of quark and antiquark PDFs. Access to the valence/sea $u$-quark and to the sea up-type antiquark PDFs, in particular, may be gained by the appropriate use of selection cuts in the rapidity of the emerging lepton pair in regions both near the $Z$-boson peak and away from it, in a manner complementary, though more indirect, to the case of the charged-current asymmetry. We study the extension of these results for the planned high-luminosity (HL) LHC.

    hep-phEPJC(2018)·35 citations
12. 12*

    Systematic analysis of radiative symmetry breaking in models with extended scalar sector

    Leonardo Chataignier🇳🇱 · Tomislav Prokopec🇳🇱 · Michael G. Schmidt🇩🇪 · Bogumila Swiezewska🇳🇱

    Radiative symmetry breaking (RSB) is a theoretically appealing framework for the generation of mass scales through quantum effects. It can be successfully implemented in models with extended scalar and gauge sectors. We provide a systematic analysis of RSB in such models: we review the common approximative methods of studying RSB, emphasising their limits of applicability and discuss the relevance of the relative magnitudes of tree-level and loop contributions as well as the dependence of the results on the renormalisation scale. The general considerations are exemplified within the context of the conformal Standard Model extended with a scalar doublet of a new SU(2)${}_X$ gauge group, the so-called SU(2)cSM. We show that various perturbative methods of studying RSB may yield significantly different results due to renormalisation-scale dependence. Implementing the renormalisation-group (RG) improvement method recently developed in arXiv:1801.05258, which is well-suited for multi-scale models, we argue that the use of the RG improved effective potential can alleviate this scale dependence providing more reliable results.

    hep-phhep-thJHEP(2018)·39 citations
13. 13*

    Bose enhancement, the Liouville effective action and the high multiplicity tail in p-A collisions

    Alex Kovner🇺🇸 · Vladimir V. Skokov🇺🇸

    In the framework of dense-dilute CGC approach we study fluctuations in the multiplicity of produced particles in p-A collisions. We show that the leading effect that drives the fluctuations is the Bose enhancement of gluons in the proton wave function. We explicitly calculate the moment generating function that resums the effects of Bose enhancement. We show that it can be understood in terms of the Liouville effective action for the composite field which is identified with the fluctuating density, or saturation momentum of the proton. The resulting probability distribution turns out to be very close to the gamma-distribution. We also calculate the first correction to this distribution which is due to pairwise Hanbury Brown-Twiss correlations of produced gluons.

    hep-phnucl-thPRD(2018)·18 citations
14. 14*

    Does shape matter? v_2 vs eccentricity in small x gluon production

    Alex Kovner🇺🇸 · Vladimir V. Skokov🇺🇸

    We study analytically and numerically effects of spatial eccentricity of the projectile shape on the second flow harmonic in inclusive gluon production in p-A collisions in the CGC framework. Keeping the collision area fixed, we find that the two quantities are anti-correlated.

    hep-phnucl-thPLB(2018)·25 citations
15. 15*

    The Relaxion Measure Problem

    Rick S. Gupta🇬🇧

    We examine the necessity of requiring that relaxion dynamics is dominated by classical slow roll and not quantum fluctuations. It has been recently proposed by Nelson and Prescod-Weinstein that abandoning this requirement can lead to a unified solution of the hierarchy and strong CP problems in QCD relaxion models. In more general models this results in a higher value of the allowed cut-off. In this work we find, however, that relaxing this condition and can result in the universe being dominated in physical volume by regions arising from large quantum fluctuations of the relaxion. These regions turn out to be problematic for the relaxion mechanism because either the relaxion does not stabilise at all or it stabilises at vacua which cannot reproduce the observed properties of our universe. The size of these undesirable regions is moreover ambiguous because of the measure problem. For instance, we show that if one chooses to use the scale factor cut-off measure such dangerous regions occupy a negligible volume and these issues do not arise.

    hep-phhep-thPRD(2018)·15 citations
16. 16*

    Constraints on ALPs and excited dark matter from the EDGES 21-cm absorption signal

    Andi Hektor🇪🇪 · Gert Hütsi🇪🇪 · Luca Marzola🇪🇪 · Ville Vaskonen🇪🇪

    The recent observation of the 21-cm absorption signal by the EDGES experiment provides a new observational window into the dynamics of the young Universe. Based on this result, we constrain the properties of ALPs and excited dark matter via the energy injections into the gaseous medium that these models produce. In particular, we derive bounds that outperform the present constraints for energy injections in the 10.2 eV to 50 keV range by analysing the intensity of Lyman-$\alpha$ photons and the electron emissivity produced by ionising radiation. Our results also show that once the standard temperature of the soft radiation background is assumed, the explanations of the observed 3.5 keV photon signal within the considered dark matter model are excluded at 95\% confidence level.

    hep-phastro-ph.COPLB(2018)·25 citations
17. 17*

    Logarithmic accuracy of parton showers: a fixed-order study

    Mrinal Dasgupta🇬🇧 · Frédéric A. Dreyer🇺🇸 · Keith Hamilton🇬🇧 · Pier Francesco Monni🇨🇭 · Gavin P. Salam🇨🇭

    We formulate some first fundamental elements of an approach for assessing the logarithmic accuracy of parton-shower algorithms based on two broad criteria: their ability to reproduce the singularity structure of multi-parton matrix elements, and their ability to reproduce logarithmic resummation results. We illustrate our approach by considering properties of two transverse momentum ordered final-state showers, examining features up to second order in the strong coupling. In particular we identify regions where they fail to reproduce the known singular limits of matrix elements. The characteristics of the shower that are responsible for this also affect the logarithmic resummation accuracies of the shower, both in terms of leading (double) logarithms at subleading $N_C$ and next-to-leading (single) logarithms at leading $N_C$.

    hep-phhep-exJHEP(2018)·149 citations
18. 18*

    Low-energy signatures of the ${\mathrm{PS}}^3$ model: from $B$-physics anomalies to LFV

    Marzia Bordone🇨🇭 · Claudia Cornella🇨🇭 · Javier Fuentes-Martin🇨🇭 · Gino Isidori🇨🇭

    The three-site Pati-Salam gauge model provides a consistent description for the hints of lepton-flavor non-universality observed in $B$ decays, connecting the present pattern of "anomalies" to the origin of the Standard Model Yukawa couplings. We present here a detailed analysis of the model predictions for a series of low-energy observables, mainly in $B$ and $\tau$ physics. The model is in good agreement with present data and predicts a well-defined pattern of non-standard effects in low-energy observables that could allow us to test it in the near future. Particularly interesting are the predictions of large $\tau \to \mu$ Lepton Flavor Violating processes, such as $\tau \to \mu \gamma$, $\tau \to 3\mu$, $B\to K\tau \mu$, and $B_s\to \tau \mu$. Also $\mu \to 3e$, $\mu \to e\gamma$, and $K_L\to \mu e$ decays could be not far from the present exclusion bounds, although this conclusion is more model dependent.

    hep-phJHEP(2018)·190 citations
19. 19*

    Safe Jet Vetoes

    Silvia Pascoli🇬🇧 · Richard Ruiz🇬🇧 · Cedric Weiland🇬🇧

    Central jet vetoes are powerful tools for reducing QCD background in measurements and searches for electroweak and colorless, new physics processes in hadron collisions. In this letter, we report the key findings of a new philosophy to designing searches for such phenomena at hadron colliders, one designed and centered around a dynamical jet veto instead a static veto applied independently of other selection criteria. Specifically, we investigate the theoretical and phenomenological consequences of setting the jet veto scale to the transverse momentum $(p_T)$ of the leading charged lepton $\ell$ in multi-lepton processes on an event-by-event basis. We consider the case of a TeV-scale heavy neutrino $N$ decaying to the trilepton final state and find the following: (i) Perturbative uncertainties associated with the veto greatly reduce due to tying the veto scale to the hard process scale. (ii) The signal efficiency for passing the veto jumps to $\gtrsim 95\%$ and exhibits little-to-no dependence on the neutrino mass scale. (iii) Top quark and `fake' lepton rejection capabilities also improve compared to only vetoing heavy flavor-tagged jets above a fixed $p_T$. This results in an increased sensitivity to active-sterile neutrino mixing by approximately an order of magnitude over the LHC's lifetime. For a Dirac neutrino with mass $m_N=150-1000$ GeV and the representative active-sterile mixing hypothesis $|V_{e4}|=|V_{\tau 4}|$ with $|V_{\mu 4}|=0$, we find that LHC experiments can probe $|V_{e4}{|}^2,|V_{\tau 4}{|}^2\lesssim 6\times 10^{-4}-8\times 10^{-3}$, surpassing the global upper limit for $m_N<450$ GeV, with $\mathcal{L}=3$ ab${}^{-1}$ of data at $\sqrt{s}=14$ TeV. Due to the color structures of the heavy $N$ production mechanisms considered, we argue that our results hold broadly for other color-singlet processes.

    hep-phhep-exPLB(2018)·31 citations
20. 20*

    Hierarchy of azimuthal anisotropy harmonics in collisions of small systems from the Color Glass Condensate

    Mark Mace🇺🇸 · Vladimir V. Skokov🇺🇸 · Prithwish Tribedy🇺🇸 · Raju Venugopalan🇺🇸

    We demonstrate that the striking systematics of two-particle azimuthal Fourier harmonics $v_2$ and $v_3$ in ultrarelativistic collisions of protons, deuterons and helium-3 ions off gold nuclei measured by the PHENIX Collaboration [arXiv:1805.02973] at the Relativistic Heavy Ion Collider (RHIC) is reproduced in the Color Glass Condensate (CGC) effective field theory. This contradicts the claim in [arXiv:1805.02973] that their data rules out initial state based explanations. The underlying systematics of the effect, as discussed previously in [arXiv:1705.00745,arXiv:1706.06260,arXiv:1801.09704], arise from the differing structure of strong color correlations between gluon domains of size $1/Q_S$ at fine ($p_{\perp }⪆Q_S$) or coarser ($p_{\perp }⪅Q_S$) transverse momentum resolution. Further tests of the limits of validity of this framework can be carried out in light-heavy ion collisions at both RHIC and the Large Hadron Collider. Such measurements also offer novel opportunities for further exploration of the role of the surprisingly large short-range nuclear correlations measured at Jefferson Lab.

    hep-phnucl-exnucl-thPRL(2018)·113 citations
21. 21*

    Twin SIMPs

    Yonit Hochberg🇮🇱 · Eric Kuflik🇮🇱 · Hitoshi Murayama🇺🇸

    The hierarchy problem and the identity of dark matter are two of the central driving forces in particle physics. Twin Higgs models provide an elegant solution to the little hierarchy problem, while Strongly Interacting Massive Particles (SIMPs) provide an appealing dark matter candidate. Here we show that SIMPs can easily be embedded in the Twin Higgs setup, such that dark matter and the hierarchy problem can be addressed in a single framework. This also provides a natural explanation to the proximity between the confinement scale of SIMP dark matter and the strong scale of QCD.

    hep-phPRD(2019)·77 citations
22. 22*

    Comparing the PYTHIA Monte Carlo to a two-component (soft + hard) model of hadron production in high-energy p-p collisions

    Thomas A. Trainor🇺🇸

    The PYTHIA Monte Carlo (PMC), first introduced more than thirty years ago, remains a popular simulation tool both for analysis of $p$-$p$ collision dynamics and for detector design and calibration. The PMC assumes that almost all produced hadrons result from parton-parton scatterings (interactions) described by pQCD (a hard component), and that multiple parton interactions per collision event (MPIs) are a common occurrence. In contrast, a two-component (soft + hard) model (TCM) of high-energy collisions, inferred inductively from a variety of data formats, attributes a majority of final-state hadrons to a soft component (projectile-nucleon dissociation) and a minority to a hard component representing minimum-bias dijet production (corresponding to measured jet spectra and fragmentation functions). The hard-component hadron yield is precisely proportional to the square of the soft-component yield over an interval corresponding to 100-fold increase in dijet production. The two data descriptions appear to be in conflict. This study presents a detailed comparison of the two models and their relations to a broad array of collision data. The PMC appears to disagree with some data, whereas the TCM provides an accurate and comprehensive data description.

    hep-phIJMPE(2019)·3 citations
23. 23*

    Stochastic Motion of Heavy Quarks in Holography: A Theory-Independent Treatment

    Dimitrios Giataganas🇹🇼

    Stochastic dynamics play a central role in strongly coupled phenomena. We present and review a theory independent approach in holography to study such phenomena. We firstly argue that the heavy quark diffusion occurs in realistic strongly coupled systems. Then we analyze the quantum and thermal fluctuation, dissipation and the corresponding Brownian motion of a heavy particle in such environments for a wide class of theories. The holographic study is based on the properties of the straight string fluctuations. The observables and coefficients associated with the stochastic motion depend on a single parameter which encodes the properties of the different theories. Moreover, certain Dp-brane fluctuations can be mapped one-to-one to the string fluctuations and therefore the stochastic brane observables can be read from the string ones. Then we review the Langevin diffusion of a moving heavy quark in generic thermal holographic theories. The analysis is based on the properties of the trailing string and its fluctuations. The string world-sheet has a black hole horizon and the quark feels an effective temperature different than the environmental one. The formulas of the effective temperature, the drag force on the particle and the Langevin coefficients are given in terms of the background metric elements readily applicable to any theory. At the end we comment on the backreaction effects on the medium and present results of the Monte Carlo simulations.

    ↳ hep-thcond-mat.str-elhep-phPoS(2018)·8 citations
24. 24*

    Dynamically integrated transport approach for heavy-ion collisions at high baryon density

    Yukinao Akamatsu🇯🇵 · Masayuki Asakawa🇯🇵 · Tetsufumi Hirano🇯🇵 · Masakiyo Kitazawa🇯🇵 · Kenji Morita🇯🇵 · Koichi Murase🇯🇵 · Yasushi Nara🇯🇵 · Chiho Nonaka🇯🇵 · Akira Ohnishi🇯🇵

    We develop a new dynamical model for high energy heavy-ion collisions in the beam energy region of the highest net-baryon densities on the basis of non-equilibrium microscopic transport model JAM and macroscopic 3+1D hydrodynamics by utilizing a dynamical initialization method. In this model,dynamical fluidization of a system is controlled by the source terms of the hydrodynamic fields. In addition, time dependent core-corona separation of hot regions is implemented. We show that our new model describes multiplicities and mean transverse mass in heavy-ion collisions within a beam energy region of $3<\sqrt{s_{NN}}<30$ GeV. Good agreement of the beam energy dependence of the $K^{+}/{\pi }^{+}$ ratio is obtained, which is explained by the fact that a part of the system is not thermalized in our core-corona approach.

    ↳ nucl-thhep-phnucl-exPRC(2018)·87 citations
25. 25*

    Black Holes' Dark Dress: On the merger rate of a subdominant population of primordial black holes

    Bradley J. Kavanagh🇳🇱 · Daniele Gaggero🇳🇱 · Gianfranco Bertone🇳🇱

    The formation of astrophysical and primordial black holes influences the distribution of dark matter surrounding them. Black holes are thus expected to carry a dark matter `dress' whose properties depend on their formation mechanism and on the properties of the environment. Here we carry out a numerical and analytical study of the merger of dressed black holes, and show that the distribution of dark matter around them dramatically affects the dynamical evolution of the binaries. Although the final impact on the merger rate of primordial black holes is rather small with respect to the case of `naked' black holes, we argue that our analysis places the calculation of this rate on more solid ground, with LIGO-Virgo observations ruling out a dark matter fraction of $10^{-3}$ for primordial black holes of 100 solar masses, and it paves the way to more detailed analyses of environmental effects induced by dark matter on the gravitational wave emission of binary black holes.

    ↳ astro-ph.COhep-phPRD(2018)·196 citations
26. 26*

    Traintracks Through Calabi-Yaus: Amplitudes Beyond Elliptic Polylogarithms

    Jacob L. Bourjaily🇩🇰 · Yang-Hui He🇬🇧 · Andrew J. McLeod🇩🇰 · Matt von Hippel🇩🇰 · Matthias Wilhelm🇩🇰

    We describe a family of finite, four-dimensional, $L$-loop Feynman integrals that involve weight-$(L+1)$ hyperlogarithms integrated over $(L-1)$-dimensional elliptically fibered varieties we conjecture to be Calabi-Yau. At three loops, we identify the relevant K3 explicitly; and we provide strong evidence that the four-loop integral involves a Calabi-Yau threefold. These integrals are necessary for the representation of amplitudes in many theories---from massless ${\phi }^4$ theory to integrable theories including maximally supersymmetric Yang-Mills theory in the planar limit---a fact we demonstrate.

    ↳ hep-thhep-phPRL(2018)·140 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.