Mon·Nov 12, 2018Monday·November 12, 2018

1. 01*

   Extending the hydrodynamical description of heavy-ion collisions to the "outer edge" of the fireball

   Adith Ramamurti🇺🇸 · Edward Shuryak🇺🇸

   It is well known that relativistic hydrodynamics provides very good description of heavy-ion collisions at RHIC/LHC energies up to transverse momenta $p_{\perp }\sim 2\text{GeV}$. In this paper, we suggest that this description can be extended to higher $p_{\perp }\sim 6\text{GeV}$, beyond which hard collisions contribute. While most previous work focused on a part of the freezeout surface at the latest proper time (referred to in this work as the "lid"), we focus on the complementary part, to be referred as "the outer edge," where the highest transverse rapidity of flow $\kappa \sim 1.4$ is achieved. We study this surface analytically, using the Riemann rarefaction wave, and numerically, using MUSIC numerical hydrodynamic code. We also use an improved freezeout condition, where the collision rate equals the expansion rate. For central collisions, we observe good description of spectra for $\pi ,K,N$ in central PbPb LHC collisions in this extended region. We further suggest that "the outer edge" has very small azimuthal asymmetry even for non-central collisions, smaller than predicted by standard hydrodynamics.

   hep-ph1 citation
2. 02*

   Pion condensation in a soft-wall AdS/QCD model

   Meng Lv🇨🇳 · Danning Li🇨🇳 · Song He🇨🇳

   Finite isospin chemical potential ${\mu }_I$ and temperature $T$ have been introduced in the framework of soft-wall AdS/QCD model. By self-consistently solve the equation of motion, we obtain the phase boundary of pion condensation phase, across which the system undergoes a phase transition between pion condensation phase and normal phase. Comparing the free energy of solutions with and without pion condensation, we find that the phase transition is of first order type both at large ${\mu }_I$ and small ${\mu }_I$. Qualitatively, the behavior at large ${\mu }_I$ is in agreement with the lattice simulation in Phys.Rev.D66(2002)034505, while the behavior at small ${\mu }_I$ is different from lattice simulations and previous studies in hard wall AdS/QCD model. This indicates that a full back-reaction model including the interaction of gluo-dynamics and chiral dynamics might be necessary to describe the small ${\mu }_I$ pion condensation phase. This study could provide certain clues to build a more realistic holographic model.

   hep-phhep-thJHEP(2019)·20 citations
3. 03*

   Weak Decays of Doubly-Heavy Tetraquarks $b\bar{c}q\bar{q}$

   Gang Li🇨🇳 · Xiao-Feng Wang🇨🇳 · Ye Xing🇨🇳

   We study the weak decays of exotic tetraquark states $b\bar{c}q\bar{q}$ with two heavy quarks. Under the SU(3) symmetry for light quarks, these tetraquarks can be classified into an octet plus a singlet: $3⨂\bar{3}=1⨁8$. We will concentrate on the octet tetraquarks with $J^P=0^{+}$, and study their weak decays, both semileptonic and nonleptonic. Hadron-level effective Hamiltonian is constructed according to the irreducible representations of the SU(3) group. Expanding the Hamiltonian, we obtain the decay amplitudes parameterized in terms of a few irreducible quantities. Based on these amplitudes, relations for decay widths are derived, which can be tested in future. We also give a list of golden channels that can be used to look for these states at various colliders.

   hep-phEPJC(2019)·15 citations
4. 04*

   Implication of family non-universal $Z^{\prime }$ model to rare exclusive $b\to s(l\bar{l},\nu \bar{\nu })$ transitions

   P. Maji🇮🇳 · P. Nayek🇮🇳 · S. Sahoo🇮🇳

   We have investigated $B\to (K,K^{\ast })(l\bar{l},\nu \bar{\nu })$ decay channels and predicted some form factor dependent observables (e.g. branching ratio, forward-backward asymmetry and lepton polarization asymmetry) considering new physics contribution from non-universal $Z^{\prime }$ model. We have found that there is appreciable difference between the standard model and $Z^{\prime }$ model predictions. Recently, the lepton flavour non-universality parameters $R_K$ and $R_{K^{\ast }}$ have been measured by the LHCb collaboration and are found to be different from their standard model predictions. These deviations provide the hint of flavor non-universality in lepton sector and motivate our research to look for new physics beyond the standard model. The $R_K$ and $R_{K^{\ast }}$ anomalies may be due to new physics in either electron or muon sector or both. In our work, we have shown that the experimental results of $R_K$ and $R_{K^{\ast }}$ could be achieved in non-universal $Z^{\prime }$ model considering the new physics couplings to muon sector only.

   hep-phPTEP(2019)·14 citations
5. 05*

   Simulation of neutron production in hadron-nucleus and nucleus-nucleus interactions in Geant4

   A. Galoyan🇷🇺 · A. Ribon🇨🇭 · V. Uzhinsky🇷🇺

   Studying experimental data obtained at ITEP [1] on neutron production in interactions of protons with various nuclei in the energy range from 747 MeV up to 8.1 GeV, we have found that slow neutron spectra have scaling and asymptotic properties [2]. The spectra weakly depend on the collision energy at momenta of projectile protons larger than 5 - 6 GeV/c. These properties are taken into account in the Geant4 Fritiof (FTF) model. The improved FTF model describes as well as the Geant4 Bertini model the experimental data on neutron production by 1.2 GeV and 1.6 GeV protons on targets (Fe, Pb) [3] and by 3.0 GeV protons on various targets (Al, Fe, Pb) [4]. For neutron production in antiproton-nucleus interactions, it was demonstrated that the FTF results are in a satisfactory agreement with experimental data of the LEAR collaboration [5]. The FTF model gives promising results for neutron production in nucleus - nucleus interactions at projectile energy 1 - 2 GeV per nucleon [6]. The observed properties allow one to predict neutron yields in the nucleus-nucleus interactions at high and very high energies. Predictions for the NICA/MPD experiment at JINR are presented.

   hep-phhep-exnucl-exEPJ Web Conf.(2019)·0 citations
6. 06*

   Heavy-Quark Symmetry Partners of the Pc(4450) Pentaquark

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

   The spectrum of heavy-hadron molecules is constrained by heavy-quark symmetry in its different manifestations. Heavy-quark spin symmetry for instance connects the properties of the ground and excited states of heavy hadrons, while heavy-antiquark-diquark symmetry connects the properties of heavy antimesons ($\bar{D}$, ${\bar{D}}^{\ast }$) and doubly heavy baryons (${\Xi }_{cc}$, ${\Xi }_{cc}^{\ast }$). A prediction of these symmetries is that if the $P_c(4450)$ is indeed a ${\bar{D}}^{\ast }{\Sigma }_c$ bound state, then there should be a series of ${\bar{D}}^{\ast }{\Sigma }_c^{\ast }$, ${\Xi }_{cc}{\Sigma }_c$, ${\Xi }_{cc}^{\ast }{\Sigma }_c$, ${\Xi }_{cc}{\Sigma }_c^{\ast }$ and ${\Xi }_{cc}^{\ast }{\Sigma }_c^{\ast }$ partners. The concrete application of heavy-quark spin symmetry indicates that, if the $P_c(4450)$ is a ${\frac{3}{2}}^{-}$ ${\bar{D}}^{\ast }{\Sigma }_c$ molecule, the existence of a ${\frac{5}{2}}^{-}$ ${\bar{D}}^{\ast }{\Sigma }_c^{\ast }$ partner with similar binding energy --- which we call $P_c(4515)$, given its expected mass --- is likely. Conversely, the application of heavy-antiquark-diquark symmetry indicates that the $0^{+}$ ${\Xi }_{cc}{\Sigma }_c$, $1^{+}$ ${\Xi }_{cc}{\Sigma }_c^{\ast }$, $2^{+}$ ${\Xi }_{cc}^{\ast }{\Sigma }_c$ and $3^{+}$ ${\Xi }_{cc}^{\ast }{\Sigma }_c^{\ast }$ molecules are likely to bind too, with binding energies in the $20-30\mathrm{MeV}$ range.

   hep-phhep-exhep-latnucl-thPRD(2018)·51 citations
7. 07*

   Peccei-Quinn symmetry from a hidden gauge group structure

   Hye-Sung Lee🇰🇷 · Wen Yin🇰🇷

   We introduce a natural origin of the Peccei-Quinn (PQ) symmetry with a sufficiently good precision. In the standard model, the baryon number symmetry U(1)_B arises accidentally due to the SU(3)_C color gauge symmetry, and it protects the proton from a decay at a sufficient level. Likewise, if there is an SU(N) gauge symmetry in the hidden sector, an accidental hidden baryon number symmetry U(1)_{B_H} can appear. The hidden baryon number is solely obtained by the structure of the SU(N) group. In particular, the quality of the U(1)_{B_H} can be arbitrarily good for an asymptotically-free theory with large enough N. The U(1)_{B_H} can be identified as a PQ symmetry. Using our findings, we build two types of novel composite axion models: a model where only one SU(N) gauge symmetry is required to both guarantee the quality and break the U(1)_{B_H}, and a model with SU(N)xSU(M) gauge symmetry where the exotic quarks responsible to the axion-gluon coupling do not confine into exotic hadrons through the dynamical breaking of the PQ symmetry, and have masses of TeV scales.

   hep-phPRD(2019)·53 citations
8. 08*

   New Physics from High Energy Tops

   Marco Farina🇺🇸 · Cristina Mondino🇺🇸 · Duccio Pappadopulo🇺🇸 · Joshua T. Ruderman🇺🇸

   Precision measurements of high energy top quarks at the LHC constitute a powerful probe of new physics. We study the effect of four fermion operators involving two tops and two light quarks on the high energy tail of the $t\bar{t}$ invariant mass distribution. We use existing measurements at a center of mass energy of 13 TeV, and state of the art calculations of the Standard Model contribution, to derive bounds on the coefficients of these operators. We estimate the projected reach of the LHC at higher luminosities and discuss the validity of these limits within the Effective Field Theory description. We find that current measurements constrain the mass scale of these operators to be larger than about 1-2 TeV, while we project that future LHC data will be sensitive to mass scales of about 3-4 TeV. We apply our bounds to constrain composite Higgs models with partial compositeness and models with approximate flavor symmetries. We find our limits to be most relevant to flavor non-universal models with a moderately large coupling of the heavy new physics states to third generation quarks.

   hep-phJHEP(2019)·23 citations
9. 09*

   Space-Time Picture of Baryon Stopping in the Color-Glass Condensate

   Larry D. McLerran🇺🇸 · Sören Schlichting🇩🇪 · Srimoyee Sen🇺🇸

   We discuss baryon stopping in the Color Glass Condensate description of high energy scattering. We consider the scattering of a distribution of valence quarks on an ultra-relativistic sheet of colored charge. We compute the distribution of scattered quarks from a composite projectile, and calculate the baryon currents before and after the collisions and on an event by event basis. We obtain simple analytic estimates of the baryon number compression and rapidity shifts, which in the idealized case of plane wave scattering, produce results that agree with considerations of Anishetty-Koehler-McLerran.

   hep-phnucl-thPRD(2019)·24 citations
10. 10*

    Muon g-2 Anomaly confronted with the higgs global data in the Left-Right Twin Higgs Models

    Guo-Li Liu🇨🇳 · Qing-Guo Zeng🇨🇳

    We will examine the Left-Right Twin Higgs(LRTH) Models as a solution of muon g-2 anomaly with the background of the Higgs global fit data. In the calculation, the joint constrains from the theory, the precision electroweak data, the 125 GeV Higgs data, the leptonic flavor changing decay \mu \to e\gamma decays, and the constraints m_{\nu_R}>m_T>m_{W_H} are all considered. And with the small mass of the \phi^0, the direct searches from the $h\to {\varphi }^0{\varphi }^0$ channels can impose stringent upper limits on Br(h\to \phi^0\phi^0) and can reduce the allowed region of m_{\phi^0} and f. It is concluded that the muon g-2 anomaly can be explained in the region of 200 GeV \leq M\leq 500 GeV, 700 GeV \leq f\leq 1100 GeV, 13 GeV \leq m_{\phi^0}\leq 55 GeV, 100 GeV \leq m_{\phi^\pm}\leq 900 GeV, and m_{\nu_R}\geq 15 TeV after imposing all the constraints mentioned above.

    hep-phEPJC(2019)·4 citations
11. 11*

    Impact parameter dependent JIMWLK evolution meets HERA data

    Heikki Mäntysaari🇫🇮 · Björn Schenke🇺🇸

    We calculate the small-$x$ evolution of protons with finite size by solving numerically the JIMWLK evolution equation. The initial condition is constrained by the HERA measurements of charm reduced cross section and of exclusive vector meson production. We compute the energy dependence of diffractive cross sections in order to access the energy evolution of the event-by-event fluctuating proton density profile. The fundamental problems arising from the regime sensitive to non-perturbatively large dipoles are also discussed.

    hep-phPoS(2018)·0 citations
12. 12*

    On the detectability of ultralight scalar field dark matter with gravitational-wave detectors

    Soichiro Morisaki🇯🇵 · Teruaki Suyama🇯🇵

    An ultralight scalar field is one of the dark matter candidates. If it couples with Standard Model particles, it oscillates mirrors in gravitational-wave detectors and generates detectable signals. We study the spectra of the signals taking into account the motion of the detectors due to the Earth's rotation/the detectors' orbital motion around the Sun and formulate a suitable data-analysis method to detect it. We find that our method can improve the existing constraints given by fifth-force experiments on one of the scalar field's coupling constants by a factor of $\sim 30$, $\sim 100$ and $\sim 350$ for $m_{\varphi }=2\times 10^{-17}\mathrm{eV},10^{-14}\mathrm{eV}$ and $10^{-12}\mathrm{eV}$ respectively, where $m_{\varphi }$ is the scalar field's mass. Our study demonstrates that experiments with gravitational-wave detectors play a complementary role to that Equivalence Principle tests do.

    hep-phgr-qcPRD(2019)·58 citations
13. 13*

    From micro to macro and back: probing near-horizon quantum structures with gravitational waves

    Andrea Maselli🇮🇹 · Paolo Pani🇮🇹 · Vitor Cardoso🇨🇭 · Tiziano Abdelsalhin🇮🇹 · Leonardo Gualtieri🇮🇹 · Valeria Ferrari🇮🇹

    Supermassive binaries detectable by the future space gravitational-wave interferometer LISA might allow to distinguish black holes from ultracompact horizonless objects, even when the latter are motivated by quantum-gravity considerations. We show that a measurement of very small tidal Love numbers at the level of $10\%$ accuracy (as achievable with "golden binaries") may also allow to distinguish between different models of these exotic compact objects, even when taking into account an intrinsic uncertainty in the object radius putatively due to quantum mechanics. We argue that there is no conceptual obstacle in performing these measurements, the main challenge remains the detectability of small tidal effects and an accurate waveform modelling. Our analysis uses only coordinate-independent quantities related to the proper radial distance and the total mass of the object.

    ↳ gr-qcastro-ph.HEhep-phClass.Quant.Grav.(2019)·47 citations
14. 14*

    Multiple Ultralight Axionic Wave Dark Matter and Astronomical Structures

    Hoang Nhan Luu🇨🇳 · S. -H. Henry Tye🇨🇳 · Tom Broadhurst🇪🇸

    An ultralight scalar boson with mass $m_1\simeq 10^{-22}$ eV is gaining credence as a Dark Matter (DM) candidate that explains the dark cores of dwarf galaxies as soliton waves. Such a boson is naturally interpreted as an axion generic in String Theory, with multiple light axions predicted in this context. We examine the possibility of soliton structures over a wide range of scales, accounting for galaxy core masses and the common presence of nuclear star clusters. We present a diagnostic soliton core mass-radius plot that provides a global view, indicating the existence of an additional axion with mass $m_2\simeq 10^{-20}$ eV, with the possibility of a third axion with mass $m_3\gtrsim 0.5\times 10^{-18}$ eV. We also argue that the relative mass densities measured for these axions are consistent with their cosmological production via the mis-alignment mechanism.

    ↳ astro-ph.GAhep-phPhys.Dark Univ.(2020)·64 citations
15. 15*

    Towards resolving the ${}_{\Lambda }^3$H lifetime puzzle

    Avraham Gal🇮🇱 · Humberto Garcilazo🇲🇽

    Recent ${}_{\Lambda }^3$H lifetime measurements in relativistic heavy ion collision experiments have yielded values shorter by (30$\pm$8)% than the free $\Lambda$ lifetime ${\tau }_{\Lambda }$, thereby questioning the naive expectation that $\tau ({}_{\Lambda }^3\mathrm{H})\approx {\tau }_{\Lambda }$ for a weakly bound $\Lambda$ hyperon. Here we apply the closure approximation introduced by Dalitz and coworkers to evaluate the ${}_{\Lambda }^3$H lifetime, using ${}_{\Lambda }^3$H wavefunctions generated by solving three-body Faddeev equations. Our result, disregarding pion final-state interaction (FSI), is $\tau ({}_{\Lambda }^3\mathrm{H})$=(0.90$\pm$0.01)${\tau }_{\Lambda }$. In contrast to previous works, pion FSI is found attractive, reducing further $\tau ({}_{\Lambda }^3\mathrm{H})$ to $\tau ({}_{\Lambda }^3\mathrm{H})$=(0.81$\pm$0.02)${\tau }_{\Lambda }$. We also evaluate for the first time $\tau ({}_{\Lambda }^3\mathrm{n})$, finding it considerably longer than ${\tau }_{\Lambda }$, contrary to the shorter lifetime values suggested by the GSI HypHI experiment for this controversial hypernucleus.

    ↳ nucl-thhep-phnucl-exPLB(2019)·44 citations
16. 16*

    A novel approach to the computation of one-loop three- and four-point functions. II - The complex mass case

    J. Ph. Guillet (1)🇫🇷 · E. Pilon (1)🇫🇷 · Y. Shimizu (2)🇯🇵 · M. S. Zidi (3) ((1) Univ. Savoie Mont Blanc, CNRS, LAPTH, Annecy, France, (2) KEK, Tsukuba, Japan, (3) LPTh, Université de Jijel, Jijel, Algérie)🇩🇿

    This article is the second of a series of three presenting an alternative method to compute the one-loop scalar integrals. It extends the results of the first article to general complex masses. Let us remind the main features enjoyed by this method. It directly proceeds in terms of the quantities driving algebraic reduction methods. It applies to the four-point functions in the same way as to the three-point functions. Lastly, it extends to kinematics more general than the one of physical e.g. collider processes relevant at one loop.

    ↳ hep-thhep-phPTEP(2020)·5 citations
17. 17*

    Constraints on the diffuse photon flux with energies above $10^{18}$ eV using the surface detector of the Telescope Array experiment

    Telescope Array Collaboration · R.U. Abbasi · M. Abe · T. Abu-Zayyad · M. Allen · R. Azuma · E. Barcikowski · J.W. Belz · D.R. Bergman · S.A. Blake · R. Cady · B.G. Cheon and 131 other authors

    We present the results of the search for ultra-high-energy photons with nine years of data from the Telescope Array surface detector. A multivariate classifier is built upon 16 reconstructed parameters of the extensive air shower. These parameters are related to the curvature and the width of the shower front, the steepness of the lateral distribution function, and the timing parameters of the waveforms sensitive to the shower muon content. A total number of two photon candidates found in the search is fully compatible with the expected background. The $95\%$CL limits on the diffuse flux of the photons with energies greater than $10^{18.0}$, $10^{18.5}$, $10^{19.0}$, $10^{19.5}$ and $10^{20.0}$ eV are set at the level of $0.067$, $0.012$, $0.0036$, $0.0013$, $0.0013\text{mbox}{km}^{-2}\text{mbox}{yr}^{-1}\text{mbox}{sr}^{-1}$ correspondingly.

    ↳ astro-ph.HEhep-exhep-phAstropart.Phys.(2019)·86 citations
18. 18*

    Elliptic flow fluctuations in central collisions of spherical and deformed nuclei

    Giuliano Giacalone🇫🇷

    Elliptic flow ($v_2$) fluctuations in central heavy-ion collisions are direct probes of the fluctuating geometry of the quark-gluon plasma, and, as such, are strongly sensitive to any deviation from spherical symmetry in the shape of the colliding nuclei. We investigate the consequences of nuclear deformation for $v_2$ fluctuations, and we assess whether current models of medium geometry are able to predict and capture such effects. Assuming linear hydrodynamic response between $v_2$ and the eccentricity of the medium, ${\epsilon }_2$, we perform accurate comparisons between model calculations of ${\epsilon }_2$ fluctuations and STAR data on cumulants of elliptic flow, in central Au+Au and U+U collisions. From these comparisons, we evince that the most distinct signatures of nuclear deformation appear in the non-Gaussianities of $v_2$ fluctuation, and we show, in particular, that the non-Gaussian $v_2$ fluctuations currently observed in central Au+Au collisions are incompatible with model calculations that implement a quadrupole coefficient of order 12\% in the ${}^{197}$Au nuclei. Finally, we make robust predictions for the behavior of higher-order cumulants of $v_2$ in collisions of non-spherical nuclei.

    ↳ nucl-thhep-phnucl-exPRC(2019)·36 citations
19. 19*

    Early Dark Energy Can Resolve The Hubble Tension

    Vivian Poulin🇺🇸 · Tristan L. Smith🇺🇸 · Tanvi Karwal🇺🇸 · Marc Kamionkowski🇺🇸

    Early dark energy (EDE) that behaves like a cosmological constant at early times (redshifts $z\gtrsim 3000$) and then dilutes away like radiation or faster at later times can solve the Hubble tension. In these models, the sound horizon at decoupling is reduced resulting in a larger value of the Hubble parameter $H_0$ inferred from the cosmic microwave background (CMB). We consider two physical models for this EDE, one involving an oscillating scalar field and another a slowly-rolling field. We perform a detailed calculation of the evolution of perturbations in these models. A Markov Chain Monte Carlo search of the parameter space for the EDE parameters, in conjunction with the standard cosmological parameters, identifies regions in which $H_0$ inferred from {\it Planck} CMB data agrees with the SH0ES local measurement. In these cosmologies, current baryon acoustic oscillation and supernova data are described as successfully as in \LCDM, while the fit to {\it Planck} data is slightly improved. Future CMB and large-scale-structure surveys will further probe this scenario.

    ↳ astro-ph.COhep-phPRL(2019)·1157 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.