Tue·Apr 14, 2020Tuesday·April 14, 2020

1. 01*

   Non-equilibrium attractor in high-temperature QCD plasmas

   Dekrayat Almaalol🇺🇸 · Aleksi Kurkela🇨🇭 · Michael Strickland🇺🇸

   We establish the existence of a far-from-equilibrium attractor in weakly-coupled gauge theory undergoing one-dimensional Bjorken expansion. We demonstrate that the resulting far-from-equilibrium evolution is insensitive to certain features of the initial condition, including both the initial momentum-space anisotropy and initial occupancy. We find that this insensitivity extends beyond the energy-momentum tensor to the detailed form of the one-particle distribution function. Based on our results, we assess different procedures for reconstructing the full one-particle distribution function from the energy-momentum tensor along the attractor and discuss implications for the freeze-out procedure used in the phenomenological analysis of ultra-relativistic nuclear collisions.

   hep-phnucl-thPRL(2020)·92 citations
2. 02*

   Lessons from eclectic flavor symmetries

   Hans Peter Nilles🇩🇪 · Saul Ramos-Sanchez🇲🇽 · Patrick K.S. Vaudrevange🇩🇪

   A top-down approach to the flavor problem motivated from string theory leads to the concept of eclectic flavor groups that combine traditional and modular flavor symmetries. To make contact with models constructed in the bottom-up approach, we analyze a specific example based on the eclectic flavor group Omega(1) (a nontrivial combination of the traditional flavor group Delta(54) and the finite modular group T') in order to extract general lessons from the eclectic scheme. We observe that this scheme is highly predictive since it severely restricts the possible group representations and modular weights of matter fields. Thereby, it controls the structure of the Kaehler potential and the superpotential, which we discuss explicitly. In particular, both Kaehler potential and superpotential are shown to transform nontrivially, but combine to an invariant action. Finally, we find that discrete R-symmetries are intrinsic to eclectic flavor groups.

   hep-phhep-thNPB(2020)·99 citations
3. 03*

   Searching for a $D\bar{D}$ bound state with the $\psi (3770)\to \gamma D^0{\bar{D}}^0$ decay

   Lianrong Dai🇨🇳 · Genaro Toledo🇲🇽 · Eulogio Oset🇪🇸

   We perform a calculation of the mass distribution in the $\psi (3770)\to \gamma D\bar{D}$ decay, studying both the $D^{+}{D}^{-}$ and $D^0{\bar{D}}^0$ decays. The electromagnetic interaction is such that the tree level amplitude is null for the neutral channel, which leaves the $\psi (3770)\to \gamma D^0{\bar{D}}^0$ proceeding through a loop involving the $D^{+}{D}^{-}\to D^0{\bar{D}}^0$ scattering amplitude. We use the results for this amplitude of a theoretical model that predicts a $D\bar{D}$ bound state and find a $D^0{\bar{D}}^0$ mass distribution in the decay drastically different than phase space. The rates obtained are relatively large and the experiment is easily feasible in the present BESIII facility. The performance of this experiment could provide an answer to the issue of this much searched for state, which is the analogue of the $f_0(980)$ resonance.

   hep-phEPJC(2020)·30 citations
4. 04*

   Analysis on the black hole formations inside old neutron stars by isospin-violating dark matter with self-interaction

   Guey-Lin Lin🇹🇼 · Yen-Hsun Lin🇹🇼

   Fermionic dark matter (DM) with attractive self-interaction is possible to form black holes (BH) inside the Gyr-old neutron stars (NS). Therefore by observing such NS corresponding to their adjacent DM environments can place bounds on DM properties, eg. DM-baryon cross section ${\sigma }_{\chi b}$, DM mass $m_{\chi }$, dark coupling ${\alpha }_{\chi }$ and mediator mass $m_{\varphi }$. In case of isospin violation, DM couples to neutron and proton in different strengths. Even NS is composed of protons roughly one to two percent of the total baryons, the contribution from protons to the DM capture rate could be drastically changed in the presence of isospin violation. We demonstrate that this effect can be important in certain cases. On the other hand, DM-forming BH inside the star is subject to many criteria and the underlying dynamics is rich with interesting features. We also systematically review the relevant physics based on the virial equation. Moreover, an accompanied python package \texttt{dm2nsbh} to realize the mechanism is also released on the github for other relevant research.

   hep-phastro-ph.HEJCAP(2020)·21 citations
5. 05*

   How EIC can help us to understand heavy-ion collisions

   Yoshitaka Hatta🇺🇸

   I give a brief overview of the science cases of the Electron-Ion Collider (EIC) with a particular emphasis on the connections to the physics of ultrarelativistic heavy-ion collisions.

   hep-phnucl-exnucl-thNPA(2021)·4 citations
6. 06*

   Supersymmetric Clockwork Axion Model and Axino Dark Matter

   Kyu Jung Bae🇰🇷 · Sang Hui Im🇰🇷

   Implications of supersymmetrizing the clockwork axions are studied. Supersymmetry ensures that the saxions and axinos have the same pattern of the coupling hierarchy as the clockwork axions. If we assume supersymmetry breaking is universal over the clockwork sites, the coupling structure is preserved, while the mass orderings of the saxions and axinos can differ depending on the supersymmetry breaking scale. While the massive saxions and axions quickly decay, the lightest axino can be stable and thus a dark matter candidate. The relic abundance of the axino dark matter from thermal production is mostly determined by decays of the heavier axinos in the normal mass ordering. This exponentially enhances the thermal yield compared to the conventional axino scenarios. Some cosmological issues are discussed.

   hep-phastro-ph.COPRD(2020)·6 citations
7. 07*

   Extracting the magnitude of magnetic field at freeze-out in heavy-ion collisions

   Kun Xu🇨🇳 · Shuzhe Shi🇨🇦 · Hui Zhang🇨🇳 · Defu Hou🇨🇳 · Jinfeng Liao🇺🇸 · Mei Huang🇨🇳

   A strong magnetic field influences significantly the masses of the charged light mesons. For example, the mass of charged pion increases with the magnetic field increasing. We propose this mechanism as a possible way to extract the magnitude of magnetic field at freeze-out in heavy ion collisions and thus help constrain its lifetime which is currently a major open question to resolve. Specifically we show that the ratio between the yield of charged pions and that of charged rhos is very sensitive to the magnetic field value at freeze-out. By using a viscous-hydrodynamic framework (iEBE-VISHNU) to simulate heavy ion collisions and implementing magnetic-field-dependent meson masses, we compute their yields and predict the dependence of such ratio on the magnetic field. We suggest to use this ratio of charged rho yield over charged pion yield as an experimental observable to extract the possible magnetic field at freeze-out in heavy ion collisions.

   hep-phnucl-exPLB(2020)·21 citations
8. 08*

   The Dark Phases of the N2HDM

   Isabell Engeln🇩🇪 · Pedro M. Ferreira🇵🇹 · M. Margarete Mühlleitner🇩🇪 · Rui Santos🇵🇹 · Jonas Wittbrodt🇸🇪

   We discuss the dark phases of the Next-to-2-Higgs Doublet model. The model is an extension of the Standard Model with an extra doublet and an extra singlet that has four distinct CP-conserving phases, three of which provide dark matter candidates. We discuss in detail the vacuum structure of the different phases and the issue of stability at tree-level of each phase. Taking into account the most relevant experimental and theoretical constraints, we found that there are combinations of measurements at the Large Hadron Collider that could single out a specific phase. The measurement of $h_{125}\to \gamma \gamma$ together with the discovery of a new scalar with specific rates to ${\tau }^{+}{\tau }^{-}$ or $\gamma \gamma$ could exclude some phases and point to a specific phase.

   hep-phJHEP(2020)·36 citations
9. 09*

   Pentaquarks with a hidden flavour and the hypothesis of the intrinsic charm of the proton

   A. V. Berezhnoy🇷🇺 · A. S. Gerasimov🇷🇺

   Using the experimental data on pentaquarks with a hidden charm, new upper limits on the intrinsic charm in the proton are obtained, possible shapes of heavy quark distributions inside the proton are discussed.

   hep-ph0 citations
10. 10*

    Nonequilibrium pion distribution within the Zubarev approach

    David Blaschke🇵🇱 · Gerd Röpke🇩🇪 · Dmitry N. Voskresensky🇷🇺 · Vladimir G. Morozov🇷🇺

    We discuss how the nonequilibrium process of pion production within the Zubarev approach of the nonequilibrium statistical operator leads to a theoretical foundation for the appearance of a nonequilibrium pion chemical potential for the pion distribution function for which there is experimental evidence in experiments at the CERN LHC.

    hep-phcond-mat.stat-mechnucl-thParticles(2020)·8 citations
11. 11*

    Precision radiative corrections to the muon polarization in the semileptonic decay of a charged kaon

    M. J. Sanchez-Glez🇲🇽 · A. Martinez🇲🇽 · C. Juarez-Leon🇲🇽 · M. Neri🇲🇽 · J. J. Torres🇲🇽 · Ruben Flores-Mendieta🇲🇽

    An expression for the Dalitz plot of the semileptonic decay of a charged kaon, including radiative corrections to order O[\alpha \pi)(q/M_1)], where q is the four-momentum transfer and M_1 is the mass of the decaying kaon, is obtained. Contributions of both the three- and four-body regions are accounted for. Besides, the emitted muon is considered to be polarized so the analysis is also focused on evaluating the radiative corrections to the longitudinal, transverse, and normal polarization components of the muon. The final formulas, with the triple integration of the bremsstrahlung photon variables ready to be performed numerically, are general enough to be used in model-independent experimental analyses whether or not the real photon is discriminated. With the numerical values of the weak form factors and slope parameters of the process, the radiative corrections to the components of the muon polarization are found to be very small compared to their respective uncorrected values.

    hep-phEur.Phys.J.Plus(2020)·1 citation
12. 12*

    Classical excluded volumes of loosely bound light (anti)nuclei and their chemical freeze-out in heavy ion collisions

    B. E. Grinyuk🇺🇦 · K. A. Bugaev🇺🇦 · V. V. Sagun🇺🇦 · O. I. Ivanytskyi🇺🇦 · D. L. Borisyuk🇺🇦 · A. S. Zhokhin🇺🇦 · G. M. Zinovjev🇺🇦 · D. B. Blaschke🇵🇱 · L. V. Bravina🇳🇴 · E. E. Zabrodin🇳🇴 · E. G. Nikonov🇷🇺 · G. Farrar🇺🇸 and 3 other authors

    From the analysis of light (anti)nuclei multiplicities that were measured recently by the ALICE collaboration in Pb+Pb collisions at the center-of-mass collision energy $\sqrt{s_{NN}}=2.76$ TeV there arose a highly non-trivial question about the excluded volume of composite particles. Surprisingly, the hadron resonance gas model (HRGM) is able to perfectly describe the light (anti)nuclei multiplicities under various assumptions. Thus, one can consider the (anti)nuclei with a vanishing hard-core radius (as the point-like particles) or with the hard-core radius of proton, but the fit quality is the same for these assumptions. It is clear, however, that such assumptions are unphysical. Hence we obtain a formula for the classical excluded volume of loosely bound light nuclei consisting of A baryons. To implement a new formula into the HRGM we have to modify the induced surface tension concept to treat the hadrons and (anti)nuclei on the same footing. We perform a simultaneous analysis of hadronic and (anti)nuclei multiplicities measured by the ALICE collaboration. The HRGM with the induced surface tension allows us to verify different assumptions on the values of hard-core radii and different scenarios of chemical freeze-out of light (anti)nuclei. It is shown that the unprecedentedly high quality of fit ${\chi }_{tot}^2/dof\simeq 0.769$ is achieved, if the chemical freeze-out temperature of hadrons is about $T_h=150$ MeV, while the one for all (anti)nuclei is $T_A=174-175.2$ MeV.

    hep-phnucl-exnucl-thIJMPE(2020)·7 citations
13. 13*

    The cosmological constant and Higgs mass with emergent gauge symmetries

    Steven D. Bass🇵🇱 · Janina Krzysiak🇵🇱

    We discuss the Higgs mass and cosmological constant in the context of an emergent Standard Model, where the gauge symmetries "dissolve" in the extreme ultraviolet. In this scenario the cosmological constant scale is suppressed by power of the large scale of emergence and expected to be of similar size to neutrino masses. Cosmology constraints then give an anthropic upper bound on the Higgs mass.

    hep-phastro-ph.COgr-qcActa Phys.Polon.B(2020)·12 citations
14. 14*

    Revisiting Majorana Neutrino Textures in the Light of Dark LMA

    Happy Borgohain🇮🇳 · Debasish Borah🇮🇳

    We study the possibility of texture zeros in Majorana light neutrino mass matrix in the light of dark large mixing angle (DLMA) solution to solar neutrino problem where solar mixing angle (${\sin }^2{\theta }_{12}\simeq 0.7$) lies in the second octant instead of first octant in standard large mixing angle (LMA) scenario (${\sin }^2{\theta }_{12}\simeq 0.3$). In three neutrino scenario, we find that LMA and DLMA solutions lead to different set of allowed and disallowed textures with one and two zeros. While being consistent with existing bounds from neutrino oscillation data, neutrinoless double beta decay and cosmology these allowed textures also lead to interesting correlations among light neutrino parameters which can distinguish LMA from DLMA solution. We also check the implications for texture zeros in $3+1$ neutrino scenario using both LMA and DLMA solutions. While LMA and DLMA solutions do not play decisive role in ruling out texture zeros in this case, they do give rise to distinct predictions and correlations between light neutrino parameters.

    hep-phJ.Phys.G(2020)·6 citations
15. 15*

    Phenomenological study of texture zeros of neutrino mass matrix in minimal left-right symmetric model

    Happy Borgohain🇮🇳 · Mrinal Kumar Das🇮🇳 · Debasish Borah🇮🇳

    We studied the phenomenological implications of texture zeros in the neutrino mass matrix of the minimal left-right symmetric model (LRSM). Since the possibility of maximum zeros reduces the maximum number of free parameters of the model making it more predictive, we considered only those cases with maximum possible texture zeros in light neutrino mass matrix $M_{\nu }$, Dirac neutrino mass matrix $M_D$ and heavy right-handed (RH) neutrino mass matrix $M_{RR}$. We then computed the correlations among the different light neutrino parameters and then the new physics contributions to neutrinoless double beta decay (NDBD) for the different texture zero cases. We find that for RH neutrino masses above 1 GeV, the new physics contributions to NDBD can saturate the corresponding experimental bound.

    hep-phJ.Phys.Conf.Ser.(2020)·0 citations
16. 16*

    Heavy-hadron molecules from light-meson-exchange saturation

    Fang-Zheng Peng🇨🇳 · Ming-Zhu Liu🇨🇳 · Mario Sánchez Sánchez🇫🇷 · Manuel Pavon Valderrama🇨🇳

    In the effective field theory framework the interaction between two heavy hadrons can be decomposed into a long- and a short-range piece. The long-range piece corresponds to the one-pion-exchange potential and is relatively well-known. The short-range piece is given by a series of contact-range interactions with unknown couplings, which substitute the less well-known short-range dynamics. While the general structure of the short-range potential between heavy hadrons is heavily constrained from heavy-quark symmetry, the couplings are still free parameters. Here we argue that the relative strength and the sign of these couplings can be estimated from the hypothesis that they are saturated by the exchange of light mesons, in particular the vector mesons $\rho$ and $\omega$, i.e. from resonance saturation. However, we propose a novel saturation procedure that effectively removes form-factor artifacts. From this we can determine in which spin and isospin configurations the low-energy constants are most attractive for specific two-heavy-hadron systems. In general the molecular states with lower isospins and higher spins will be more attractive and thus more probable candidates to form heavy-hadron molecules. This pattern is compatible with the interpretation of the $X(3872)$ and $P_c(4312/4440/4457)$ as molecular states, but it is not applicable to states with maximum isospin like the $Z_c(3900/4020)$.

    hep-phhep-exhep-latnucl-thPRD(2020)·37 citations
17. 17*

    Mass spectrum and strong decays of strangeonium in a constituent quark model

    Qi Li🇨🇳 · Long-Cheng Gui🇨🇳 · Ming-Sheng Liu🇨🇳 · Qi-Fang Lü🇨🇳 · Xian-Hui Zhong🇨🇳

    In this work we calculate the mass spectrum of strangeonium up to the $3D$ multiplet within a nonrelativistic linear potential quark model. Furthermore, using the obtained wave functions, we also evaluate the strong decays of the strangeonium states with the ${}^3{P}_0$ model. Based on our successful explanations of the well established states $\varphi (1020)$, $\varphi (1680)$, $h_1(1415)$, $f_2^{\prime }(1525)$, and ${\varphi }_3(1850)$, we further discuss the possible assignments of strangeonium-like states from experiments by combining our theoretical results with the observations. It is found that some resonances, such as $f_2(2010)$ and $f_2(2150)$ listed by the Particle Data Group, and $X(2062)$ and $X(2500)$ newly observed by BESIII, may be interpreted as the strangeonium states. The possibility of $\varphi (2170)$ as a candidate for $\varphi (3S)$ or $\varphi (2D)$ cannot be excluded. We expect our results to provide useful references for looking for the missing $s\bar{s}$ states in future experiments.

    hep-phhep-exCPC(2021)·59 citations
18. 18*

    Mode Decomposed Chiral Magnetic Effect and Rotating Fermions

    Kenji Fukushima🇯🇵 · Takuya Shimazaki🇯🇵 · Lingxiao Wang🇨🇳

    We present a novel perspective to characterize the chiral magnetic and related effects in terms of angular decomposed modes. We find that the vector current and the chirality density are connected through a surprisingly simple relation for all the modes and any mass, which defines the mode decomposed chiral magnetic effect in such a way free from the chiral chemical potential. The mode decomposed formulation is useful also to investigate properties of rotating fermions. For demonstration we give an intuitive account for a nonzero density emerging from a combination of rotation and magnetic field as well as an approach to the chiral vortical effect at finite density.

    hep-phquant-phPRD(2020)·18 citations
19. 19*

    Searching for Odderon in Central Exclusive Processes at the LHC

    Piotr Lebiedowicz🇵🇱

    There seem to be recently an evidence for $C=-1$ odderon exchange in proton-proton elastic scattering at high energies. Here we discuss three different central-exclusive-production processes $pp\to pp(\varphi \to K^{+}{K}^{-})$, $pp\to pp(\varphi \to {\mu }^{+}{\mu }^{-})$, and $pp\to pp\varphi \varphi \to pp{K}^{+}{K}^{-}{K}^{+}{K}^{-}$, as a possible source of information for soft odderon exchange. The theoretical results are calculated within the tensor-pomeron and vector-odderon model for soft reactions. We include absorptive corrections at the amplitude level. To describe the low-energy data measured in the past by the WA102 collaboration we consider also subleading processes with reggeized vector-meson exchanges and reggeons. We discuss possible evidences for odderon exchange at the low energies and try to make predictions at the LHC.

    hep-phActa Phys.Polon.B(2020)·1 citation
20. 20*

    Dark charge versus electric charge

    Duong Van Loi🇻🇳 · Cao H. Nam🇻🇳 · Ngo Hai Tan🇻🇳 · Phung Van Dong🇻🇳

    We revisit a theory that proposes a dark charge, $D$, as a dequantization of the electric charge, $Q$. We find that the general arguments of anomaly cancelation and fermion mass generation yield both $D$ and $Q$, nontrivially unified with the weak isospin $T_i$ $(i=1,2,3)$ in a novel gauge symmetry, $SU(3{)}_C\otimes SU(2{)}_L\otimes U(1{)}_Y\otimes U(1{)}_N$, where $Y$ and $N$ determine $Q$ and $D$ through the $T_3$ operator, i.e. $Q=T_3+Y$ and $D=T_3+N$, respectively. A new observation is that fundamental particles possess a dynamical dark charge which governs both neutrino mass and dark matter, where the neutrino mass is determined via a canonical seesaw, while the dark matter stability is ensured by electric and color charge conservations. We examine the mass spectra of fermions, scalars, and gauge bosons, as well as their interactions, taking into account the kinetic mixing effect of $U(1{)}_{Y,N}$ gauge fields. The new physics phenomena at colliders are examined. The dark matter relic density and detection are discussed.

    hep-phhep-thPRD(2022)·9 citations
21. 21*

    Exploring the spectrum of the hidden charm strange pentaquark in an SU(4) flavor-spin model

    Fl. Stancu🇧🇪

    We study the spectrum of the isoscalar pentaquark $udsc\overline{c}$, of either positive or negative parity, in a constituent quark model with linear confinement and a flavor-spin hyperfine interaction previously extended to SU(4) and used to describe the spectrum of the $uudc\overline{c}$ pentaquarks observed at LHCb in 2019. For positive parity we make a distinction between the case where one unit of angular momentum is located in the subsystem of four quarks and the case where the angular momentum is located in the relative motion between a ground state four-quark subsystem and the antiquark. The novelty is that we introduce the coupling between different flavor states, due to the breaking of exact SU(4)-flavor symmetry of the Hamiltonian model, both for positive and negative parity states. An important consequence is that the lowest state, located at 4404 MeV, has quantum numbers $J^P$ = $1/2^{-}$ while without coupling the lowest state has $J^P$ = $1/2^{+}$ or $3/2^{+}$.

    hep-phPRD(2020)·9 citations
22. 22*

    Evolution of strange and multi-strange hadron production with relative transverse multiplicity activity in underlying event

    Prabhakar Palni🇵🇱 · Arvind Khuntia🇵🇱 · Paolo Bartalini🇲🇽

    In this work, the relative Underlying Event (UE) transverse multiplicity activity classifier ($R_{\mathrm{T}}$) is used to study the strange and multi-strange hadron production in proton-proton collisions. Our study with $R_{\mathrm{T}}$ would allow to disentangle these particles, which are originating from the soft and hard QCD processes. We have used the PYTHIA 8 Monte-Carlo (MC) with a different implementation of color reconnection and rope hadronization models to demonstrate the proton-proton collisions data at $\sqrt{s}$ = 13 TeV. The relative production of strange and multi-strange hadrons are discussed extensively in low and high transverse activity regions. In this contribution, the relative strange hadron production is enhanced with increasing $R_{\mathrm{T}}$. This enhancement is significant for the strange baryons as compared to mesons. In addition, the particle ratios as a function of $R_{\mathrm{T}}$ confirm the baryon enhancement in new Color Reconnection (newCR), whereas the Rope model confirms the baryon enhancement only with strange quark content. Experimental confirmation of such results will provide more insight into the soft physics in the transverse region, which will be useful to investigate various tunes based on hadronization and color reconnection schemes.

    hep-phnucl-thEPJC(2020)·5 citations
23. 23*

    New method for fitting the low-energy constants in chiral perturbation theory

    Qin-He Yang🇨🇳 · Wei Guo🇨🇳 · Feng-Jun Ge🇨🇳 · Bo Huang🇨🇳 · Hao Liu🇨🇳 · Shao-Zhou Jiang🇨🇳

    A new set of the next-to-leading order (NLO) and the next-to-next-to-leading order (NNLO) low-energy constants $L_i^r$ and $C_i^r$ in chiral perturbation theory is obtained. These values are computed using the new experimental data with a new calculation method. This method combines the traditional global fit and Monte Carlo method together. The higher order contributions are estimated with this method. The theoretical values of the observables provide good convergence at each chiral dimension, except for the NNLO values of the $\pi K$ scattering lengths $a_0^{3/2}$ and $a_0^{1/2}$. The fitted values for $L_i^r$ at NLO are close to their results with the new method at NNLO; i.e., these $L_i^r$ are nearly order-independent in this method. The estimated ranges for $C_i^r$ are consistent with those in the literature, and their possible upper or/and lower boundaries are given. The values of some linear combinations of $C_i^r$ are also given, and they are more reliable. If one knows a more exact value $C_i^r$, another $C_i^r$ can be obtained by these values.

    hep-phPRD(2020)·1 citation
24. 24*

    A Natural Composite Higgs via Universal Boundary Conditions

    Simone Blasi🇩🇪 · Csaba Csaki🇺🇸 · Florian Goertz🇩🇪

    We present a novel realization of a composite Higgs, which can naturally produce top partners above the current LHC bounds without increasing the tuning above 10%. The essential ingredients are softened breaking of the Higgs shift symmetry as well as maximal symmetry, which turn out to perfectly complement each other. The 5D realization of this model is particularly simple: universal UV and IR boundary conditions for the bulk fermions containing the SM fields will cure the problems of existing holographic composite Higgs models and provide a complete viable model for a naturally light Higgs without much tuning.

    hep-phhep-thSciPost Phys.(2021)·17 citations
25. 25*

    A New Precision Process at FCC-hh: the diphoton leptonic Wh channel

    Fady Bishara🇩🇪 · Philipp Englert🇩🇪 · Christophe Grojean🇩🇪 · Marc Montull🇩🇪 · Giuliano Panico🇮🇹 · Alejo N. Rossia🇩🇪

    The increase in luminosity and center of mass energy at the FCC-hh will open up new clean channels where BSM contributions are enhanced at high energy. In this paper we study one such channel, $Wh\to \ell \nu \gamma \gamma$. We estimate the sensitivity to the ${\mathcal{O}}_{\phi q}^{(3)}$, ${\mathcal{O}}_{\phi W}$, and ${\mathcal{O}}_{\phi \tilde{W}}$ SMEFT operators. We find that this channel will be competitive with fully leptonic $WZ$ production in setting bounds on ${\mathcal{O}}_{\phi q}^{(3)}$. We also find that the double differential distribution in the $p_T^h$ and the leptonic azimuthal angle can be exploited to enhance the sensitivity to ${\mathcal{O}}_{\phi \tilde{W}}$. However, the bounds on ${\mathcal{O}}_{\phi W}$ and ${\mathcal{O}}_{\phi \tilde{W}}$ we obtain in our analysis, though complementary and more direct, are not competitive with those coming from other measurements such as EDMs and inclusive Higgs measurements.

    hep-phhep-exJHEP(2020)·20 citations
26. 26*

    A Robust Measure of Event Isotropy at Colliders

    Cari Cesarotti🇺🇸 · Jesse Thaler🇺🇸

    We introduce a new event shape observable -- event isotropy -- that quantifies how close the radiation pattern of a collider event is to a uniform distribution. This observable is based on a normalized version of the energy mover's distance, which is the minimum "work" needed to rearrange one radiation pattern into another of equal energy. We investigate the utility of event isotropy both at electron-positron colliders, where events are compared to a perfectly spherical radiation pattern, as well as at proton-proton colliders, where the natural comparison is to either cylindrical or ring-like patterns. Compared to traditional event shape observables like sphericity and thrust, event isotropy exhibits a larger dynamic range for high-multiplicity events. This enables event isotropy to not only distinguish between dijet and multijet processes but also separate uniform N-body phase space configurations for different values of N. As a key application of this new observable, we study its performance to characterize strongly-coupled new physics scenarios with isotropic collider signatures.

    hep-phhep-exJHEP(2020)·61 citations
27. 27*

    Asymptotic behavior of meson transition form factors

    Martin Hoferichter🇨🇭 · Peter Stoffer🇺🇸

    One of the open issues in evaluations of the contribution from hadronic light-by-light scattering to the anomalous magnetic moment of the muon $(g-2{)}_{\mu }$ concerns the role of heavier scalar, axial-vector, and tensor-meson intermediate states. The coupling of axial vectors to virtual photons is suppressed for small virtualities by the Landau-Yang theorem, but otherwise there are few rigorous constraints on the corresponding form factors. In this paper, we first derive the Lorentz decomposition of the two-photon matrix elements into scalar functions following the general recipe by Bardeen, Tung, and Tarrach. Based on this decomposition, we then calculate the asymptotic behavior of the meson transition form factors from a light-cone expansion in analogy to the asymptotic limits for the pseudoscalar transition form factor derived by Brodsky and Lepage. Finally, we compare our results to existing data as well as previous models employed in the literature.

    hep-phhep-exhep-latnucl-thJHEP(2020)·103 citations
28. 28*

    Mass spectrum of pseudo-scalar glueballs from a Bethe-Salpeter approach with the rainbow-ladder truncation

    L.P. Kaptari🇷🇺 · B. Kämpfer🇩🇪

    We suggest a framework based on the rainbow approximation to the Dyson-Schwinger and Bethe-Salpeter equations with effective parameters adjusted to lattice QCD data to calculate the masses of the ground and excited states of pseudo-scalar glueballs. The structure of the truncated Bethe-Salpeter equation with the gluon and ghost propagators as solutions of the truncated Dyson-Schwinger equations is analysed in Landau gauge. Both, the Bete-Salpeter and Dyson-Schwinger equations, are solved numerically within the same rainbow-ladder truncation with the same effective parameters which ensure consistency of the approach. We found that with a set of parameters, which provides a good description of the lattice data within the Dyson-Schwinger approach, the solutions of the Bethe Salpeter equation for the pseudo-scalar glueballs exhibit a rich mass spectrum which also includes the ground and excited states predicted by lattice calculations. The obtained mass spectrum contains also several intermediate excitations beyond the lattice approaches. The partial Bethe-Salpeter amplitudes of the pseudo-scalar glueballs are presented as well.

    hep-phnucl-thFew Body Syst.(2020)·22 citations
29. 29*

    Correlation between global polarization, angular momentum and flow in heavy-ion collisions

    Yu. B. Ivanov🇷🇺 · A. A. Soldatov🇷🇺

    Possible correlations of the global polarization of $\Lambda$ hyperons with the angular momentum and transverse flow in the central region of colliding nuclei are studied based on refined estimate of the global polarization. Simulations of Au+Au collisions at collision energies $\sqrt{s_{NN}}=$ 6-40 GeV are performed within the model of the three-fluid dynamics. Within the crossover and first-order-phase-transition scenarios this refined estimate quite satisfactorily reproduces the experimental STAR data. Hadronic scenario fails at high collision energies, $\sqrt{s_{NN}}>$ 10 GeV, and even predicts opposite sign of the global polarization. It is found that the global polarization correlates with neither the angular momentum accumulated in the central region nor with directed and elliptic flow. At the same time we observed correlation between the angular momentum and directed flow in both their time and collision-energy dependence. These results suggest that, although initially the angular momentum is the driving force for the vortex generation, later the angular momentum and vortex motion become decorrelated in the midrapidity region. Then the midrapidity angular momentum is determined by the pattern of the directed flow and even becomes negative when the antiflow occurs. At the freeze-out stage, the dominant part of the participant angular momentum is accumulated in the fragmentation regions.

    ↳ nucl-thhep-phPRC(2020)·39 citations
30. 30*

    Barotropic fluid compatible parametrizations of dark energy

    Dalibor Perkovic🇭🇷 · Hrvoje Stefancic🇭🇷

    Parametrizations of Equation of state parameter as a function of the scale factor or redshift are frequently used in dark energy modeling. The question investigated in this paper is if parametrizations proposed in the literature are compatible with the dark energy being a barotropic fluid. The test of this compatibility is based on the functional form of the speed of sound squared, which for barotropic fluid dark energy follows directly from the function for the Equation of state parameter. The requirement that the speed of sound squared should be between 0 and speed of light squared provides constraints on model parameters using analytical and numerical methods. It is found that this fundamental requirement eliminates a large number of parametrizations as barotropic fluid dark energy models and puts strong constraints on parameters of other dark energy parametrizations.

    ↳ gr-qcastro-ph.COhep-phEPJC(2020)·28 citations
31. 31*

    Deconfinement transition line with the Complex Langevin equation up to $\mu /T\sim 5$

    M. Scherzer🇩🇪 · D. Sexty🇩🇪 · I.-O. Stamatescu🇩🇪

    We study the deconfinement transition line in QCD for quark chemical potentials up to ${\mu }_q\sim 5T$ (${\mu }_B\sim 15T$). To circumvent the sign problem we use the complex Langevin equation with gauge cooling. The plaquette gauge action is used with two flavors of naive Wilson fermions at a relatively heavy pion mass of roughly 1.3 GeV. A quadratic dependence describes the transition line well on the whole chemical potential range.

    ↳ hep-lathep-phPRD(2020)·34 citations
32. 32*

    Momentum-dependent potential and collective flows within the relativistic quantum molecular dynamics approach based on relativistic mean-field theory

    Yasushi Nara🇯🇵 · Tomoyuki Maruyama🇯🇵 · Horst Stoecker🇩🇪

    Relativistic quantum molecular dynamics based on the relativistic mean field theory (RQMD.RMF) is extended by including momentum-dependent potential. The equation of state (EoS) dependence of the directed and the elliptic flow of protons in the beam energy range of $2.3<\sqrt{s_{NN}}<20$ GeV is examined. It is found that the directed flow depends strongly on the optical potential at high energies,$\sqrt{s_{NN}}>3$ GeV, where no information is available experimentally. The correlation between effective mass at saturation density and the optical potential is found: smaller values of effective mass require smaller strengths of the optical potential to describe the directed flow data.This correlation can also be seen in the beam energy dependence of the elliptic flow at $\sqrt{s_{NN}}>3$ GeV, although its effect is rather weak. On the other hand, stiff EoS is required to describe the elliptic flow at lower energies.Experimental constraints on the optical potential from $pA$ collisions will provide important information on the EoS at high energies.The proton directed and the elliptic flow are well described in the RQMD.RMF model from $\sqrt{s_{NN}}=2.3$ to 8.8 GeV. In contrast,to reproduce the collapse of the directed flow above 10 GeV, pressure has to be reduced, which indicates a softening of the EoS around $\sqrt{s_{NN}}=10$ GeV.

    ↳ nucl-thhep-phnucl-exPRC(2020)·68 citations
33. 33*

    Spin vortex lattice in the Landau vortex-free state of rotating superfluids

    G.E. Volovik🇫🇮

    We show that the Landau vortex-free state in rotating container may give rise to the lattice of spin vortices. We consider this effect on example of spin vortices in magnon Bose-Einstein condensate (the phase coherent spin precession) in the B-phase of superfluid ${}^3$He, and on example of spin vortices in the polar phase of ${}^3$He.

    ↳ cond-mat.otherhep-phJETP Lett.(2020)·2 citations
34. 34*

    Probing the holographic dilaton

    Daniel Elander🇫🇷 · Maurizio Piai🇬🇧 · John Roughley🇬🇧

    Many strongly coupled field theories admit a spectrum of gauge-invariant bound states that includes scalar particles with the same quantum numbers as the vacuum. The challenge naturally arises of how to characterise them. In particular, how can a dilaton---the pseudo-Nambu-Goldstone boson associated with approximate scale invariance---be distinguished from other generic light scalars with the same quantum numbers? We address this problem within the context of gauge-gravity dualities, by analysing the fluctuations of the higher-dimensional gravitational theory. The diagnostic test that we propose consists of comparing the results of the complete calculation, performed by using gauge-invariant fluctuations in the bulk, with the results obtained in the probe approximation. While the former captures the mixing between scalar and metric degrees of freedom, the latter removes by hand the fluctuations that source the dilatation operator of the boundary field-theory. Hence, the probe approximation cannot capture a possible light dilaton, while it should fare well for other scalar particles. We test this idea on a number of holographic models, among which are some of the best known, complete gravity backgrounds constructed within the top-down approach to gauge-gravity dualities. We compute the spectra of scalar and tensor fluctuations, that are interpreted as bound states (glueballs) of the dual field theory, and we highlight those cases in which the probe approximation yields results close to the correct physical ones, as well as those cases where significant discrepancies emerge. We interpret the latter occurrence as an indication that identifying one of the lightest scalar states with the dilaton is legitimate, at least as a leading-order approximation.

    ↳ hep-thhep-lathep-phJHEP(2020)·32 citations
35. 35*

    The QCD critical point from the Nambu-Jona-Lasino model with a scalar-vector interaction

    Kai-Jia Sun🇺🇸 · Che-Ming Ko🇺🇸 · Shanshan Cao🇺🇸 · Feng Li🇨🇳

    We study the critical point in the QCD phase diagram in the Nambu-Jona-Lasino (NJL) model by including a scalar-vector coupled interaction. We find that varying the strength of this interaction, which has no effect on the vacuum properties of QCD, can significantly affect the location of the critical point in the QCD phase diagram, particularly the value of the cirtical temperature. This provides a convenient way to use the NJL-based transport or hydrodynamic model to extract information about the QCD phase diagram from relativistic heavy-ion collisions.

    ↳ nucl-thhep-phPRD(2021)·18 citations
36. 36*

    Comments on magnetic black holes

    Juan Maldacena🇺🇸

    We discuss aspects of magnetically charged black holes in the Standard Model. For a range of charges, we argue that the electroweak symmetry is restored in the near horizon region. The extent of this phase can be macroscopic. If $Q$ is the integer magnetic charge, the fermions lead to order $Q$ massless two dimensional fermions moving along the magnetic field lines. These greatly enhance Hawking radiation effects.

    ↳ hep-thgr-qchep-phJHEP(2021)·124 citations
37. 37*

    Seeding primordial black holes in multifield inflation

    Gonzalo A. Palma🇨🇱 · Spyros Sypsas🇹🇭 · Cristobal Zenteno🇨🇱

    The inflationary origin of primordial black holes (PBHs) relies on a large enhancement of the power spectrum ${\Delta }_{\zeta }$ of the curvature fluctuation $\zeta$ at wavelengths much shorter than those of the cosmic microwave background anisotropies. This is typically achieved in models where $\zeta$ evolves without interacting significantly with additional (isocurvature) scalar degrees of freedom. However, quantum gravity inspired models are characterized by moduli spaces with highly curved geometries and a large number of scalar fields that could vigorously interact with $\zeta$ (as in the cosmological collider picture). Here we show that isocurvature fluctuations can mix with $\zeta$ inducing large enhancements of its amplitude. This occurs whenever the inflationary trajectory experiences rapid turns in the field space of the model leading to amplifications that are exponentially sensitive to the total angle swept by the turn, which induce characteristic observable signatures on ${\Delta }_{\zeta }$. We derive accurate analytical predictions and show that the large enhancements required for PBHs demand non-canonical kinetic terms in the action of the multifield system.

    ↳ astro-ph.COgr-qchep-phhep-thPRL(2020)·202 citations
38. 38*

    Warm Decaying Dark Matter and the Hubble Tension

    Nikita Blinov🇺🇸 · Celeste Keith🇺🇸 · Dan Hooper🇺🇸

    If a fraction of the dark matter is unstable and decays into dark radiation at around the time of matter-radiation equality, it could impact the expansion history of the universe in a way that helps to ameliorate the long-standing tension between the locally measured value of the Hubble constant and the value inferred from measurements of the cosmic microwave background and baryon acoustic oscillations (assuming standard $\Lambda$CDM cosmology). If this component of decaying dark matter is cold, however, it will modify the evolution of the gravitational potentials, leading to inconsistencies with these same data sets. With this in mind, we consider here a component of decaying warm dark matter, with a free-streaming length that is long enough to remain consistent with existing data. We study the background and perturbation evolution of warm decaying dark matter, and use cosmological data to constrain the mass, abundance and decay rate of such a particle. We find that a component of warm decaying dark matter can significantly reduce the tension between local and cosmological determinations of the Hubble constant.

    ↳ astro-ph.COhep-phJCAP(2020)·68 citations
39. 39*

    Impact of transforming to Conformal Fermi Coordinates on Quasi-Single Field Non-Gaussianity

    Adriano Testa🇺🇸 · Mark B. Wise🇺🇸

    In general relativity predictions for observable quantities can be expressed in a coordinate independent way. Nonetheless it may be inconvenient to do so. Using a particular frame may be the easiest way to connect theoretical predictions to measurable quantities. For the cosmological curvature bispectrum such frame is described by the Conformal Fermi Coordinates. In single field inflation it was shown that going to this frame cancels the squeezed limit of the density perturbation bispectrum calculated in Global Coordinates. We explore this issue in quasi single field inflation when the curvaton mass and the curvaton-inflaton mixing are small. In this case, the contribution to the bispectrum from the coordinate transformation to Conformal Fermi Coordinates is of the same order as that from the inflaton-curvaton interaction term but does not cancel it.

    ↳ astro-ph.COhep-phPRD(2020)·3 citations
40. 40*

    Holographic Naturalness

    Andrea Addazi🇨🇳

    The Holographic Naturalness (HN) is a new paradigm towards an explanation of the Cosmological Constant (CC) and the Higgs Hierarchy (HH) in the Universe. Motivated by the Holographic Principle, and inspired by the (A)dS/CFT correspondence, we elaborate on the possibility and on the cosmological consequences of a fundamental intrinsic disorder and temperature in "vacuo". We postulate that the zero vacuum entropy is provided by a large number of quantum hair fields, the "hairons". The quantum hairon gas in space-time induces an effective decoherence effect to the Standard Model (SM) particle sector. This is leading to an entropic reinterpretation of UV divergent contributions to CC and HH: we will show that, in both the cases, the large number of re-scatterings on the hairon ensamble suppresses any radiative instabilities. The CC and HH problems are illusions envisaged by a conscious observer, having access on the limited amount of informations from SM tests: both the issues are originated from our ignorance of the hidden entropy intrinsically stored in the space-time. The HN suggests to search for effective decoherence effects in particle physics observables such as effective CPT, Unitarity and Energy violations. Regarding the HH, the HN does not introduce any new particles or interactions around the TeV-scale: we do not expect for any signatures, at LHC and any future high energy colliders, related to the Higgs UV completion in a Wilsonian sense.

    ↳ hep-thgr-qchep-phInt.J.Mod.Phys.D(2020)·12 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.