Tue·Sep 20, 2016Tuesday·September 20, 2016

1. 01*

   Emission of Photons and Relativistic Axions from Axion Stars

   Eric Braaten🇺🇸 · Abhishek Mohapatra🇺🇸 · Hong Zhang🇺🇸

   The number of nonrelativistic axions can be changed by inelastic reactions that produce photons or relativistic axions. Any odd number of axions can annihilate into two photons. Any even number of nonrelativistic axions can scatter into two relativistic axions. We calculate the rate at which axions are lost from axion stars from these inelastic reactions. In dilute systems of axions, the dominant inelastic reaction is axion decay into two photons. In sufficiently dense systems of axions, the dominant inelastic reaction is the scattering of four nonrelativistic axions into two relativistic axions. The scattering of odd numbers of axions into two photons produces monochromatic radio-frequency signals at odd-integer harmonics of the fundamental frequency set by the axion mass. This provides a unique signature for dense systems of axions, such as a dense axion star or a collapsing dilute axion star.

   hep-phastro-ph.COPRD(2017)·61 citations
2. 02*

   Theory News Higgs

   Joachim Brod🇩🇪

   I review new developments in Higgs physics, with a focus on Yukawa couplings in and beyond the standard model. In particular, I discuss different methods of measuring the light Yukawas, new sources of CP violation in the Higgs sector, and lepton flavor violation.

   hep-phPoS(2016)·0 citations
3. 03*

   Violent Preheating in Inflation with Nonminimal Coupling

   Yohei Ema🇯🇵 · Ryusuke Jinno🇯🇵 · Kyohei Mukaida🇯🇵 · Kazunori Nakayama🇯🇵

   We study particle production at the preheating era in inflation models with nonminimal coupling $\xi {\varphi }^{2}R$ and quartic potential $\lambda {\varphi }^4/4$ for several cases: real scalar inflaton, complex scalar inflaton and Abelian Higgs inflaton. We point out that the preheating proceeds much more violently than previously thought. If the inflaton is a complex scalar, the phase degree of freedom is violently produced at the first stage of preheating. If the inflaton is a Higgs field, the longitudinal gauge boson production is similarly violent. This is caused by a spike-like feature in the time dependence of the inflaton field, which may be understood as a consequence of the short time scale during which the effective potential or kinetic term changes suddenly. The produced particles typically have very high momenta $k\lesssim \sqrt{\lambda }{M}_{\text{P}}$. The production might be so strong that almost all the energy of the inflaton is carried away within one oscillation for ${\xi }^2\lambda \gtrsim \mathcal{O}(100)$. This may partly change the conventional understandings of the (p)reheating after inflation with the nonminimal coupling to gravity such as Higgs inflation. We also discuss the possibility of unitarity violation at the preheating stage.

   hep-phastro-ph.COgr-qchep-thJCAP(2017)·179 citations
4. 04*

   Chiral Soliton Lattice and Charged Pion Condensation in Strong Magnetic Fields

   Tomas Brauner🇳🇴 · Naoki Yamamoto🇯🇵

   The Chiral Soliton Lattice (CSL) is a state with a periodic array of topological solitons that spontaneously breaks parity and translational symmetries. Such a state is known to appear in chiral magnets. We show that CSL also appears as a ground state of quantum chromodynamics at nonzero chemical potential in a magnetic field. By analyzing the fluctuations of the CSL, we furthermore demonstrate that in strong but achievable magnetic fields, charged pions undergo Bose-Einstein condensation. Our results, based on a systematic low-energy effective theory, are model-independent and fully analytic.

   hep-phcond-mat.str-elhep-thJHEP(2017)·101 citations
5. 05*

   Searching for spin-3/2 leptons

   Mohammad Abdullah🇺🇸 · Kevin Bauer🇺🇸 · Luis Gutierrez🇺🇸 · John Sandy🇺🇸 · Daniel Whiteson🇺🇸

   A model of spin-3/2 vector-like leptons is introduced, which serve as an alternative probe of possible lepton compositeness. Possible signatures at the Large Hadron Collider are explored, and current data are used to constrain the masses of the hypothetical new leptons.

   hep-phhep-exPRD(2017)·6 citations
6. 06*

   QCD analysis of nucleon structure functions in deep-inelastic neutrino-nucleon scattering: Laplace transform and Jacobi polynomials approach

   S. Mohammad Moosavi Nejad🇮🇷 · Hamzeh Khanpour🇮🇷 · S. Atashbar Tehrani🇮🇷 · Mahdi Mahdavi🇮🇷

   We present a detailed QCD analysis of nucleon structure functions $x{F}_3(x,Q^2)$, based on Laplace transforms and Jacobi polynomials approach. The analysis corresponds to the next-to-leading order and next-to-next-to-leading order approximation of perturbative QCD. The Laplace transform technique, as an exact analytical solution, is used for the solution of nonsinglet Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equations at low- and large-$x$ values. The extracted results are used as input to obtain the $x$ and Q${}^2$ evolution of $x{F}_3(x,Q^2)$ structure functions using the Jacobi polynomials approach. In our work, the values of the typical QCD scale ${\Lambda }_{\overline{\mathrm{MS}}}^{(n_f)}$ and the strong coupling constant ${\alpha }_s(M_Z^2)$ are determined for four quark flavors ($n_f=4$) as well. A careful estimation of the uncertainties shall be performed using the Hessian method for the valence-quark distributions, originating from the experimental errors. We compare our valence-quark parton distribution functions sets with those of other collaborations; in particular with the {\tt BBG}, {\tt CT14}, {\tt MMHT14} and {\tt NNPDF} sets, which are contemporary with the present analysis. The obtained results from the analysis are in good agreement with those from the literature.

   hep-phPRC(2016)·37 citations
7. 07*

   Vector dark matter annihilation with internal bremsstrahlung

   Gulab Bambhaniya🇮🇳 · Jason Kumar🇺🇸 · Danny Marfatia🇺🇸 · Alekha C. Nayak🇮🇳 · Gaurav Tomar🇮🇳

   We consider scenarios in which the annihilation of self-conjugate spin-1 dark matter to a Standard Model fermion-antifermion final state is chirality suppressed, but where this suppression can be lifted by the emission of an additional photon via internal bremsstrahlung. We find that this scenario can only arise if the initial dark matter state is polarized, which can occur in the context of self-interacting dark matter. In particular, this is possible if the dark matter pair forms a bound state that decays to its ground state before the constituents annihilate. We show that the shape of the resulting photon spectrum is the same as for self-conjugate spin-0 and spin-1/2 dark matter, but the normalization is less heavily suppressed in the limit of heavy mediators.

   hep-phastro-ph.HEhep-exPLB(2017)·14 citations
8. 08*

   Theory of hard probes in PbPb collisions

   Yang-Ting Chien🇺🇸

   The jet quenching phenomenon in heavy ion collisions provides a strong evidence of the modification of parton shower in the quark-gluon plasma. This contribution focuses on the hard probes of QGP using jets and summarizes the new theoretical progress of jet substructure modification studies using effective field theory techniques. We emphasize the important role of jet substructure observables as they probe various aspects of the jet formation mechanism and allow us to study the medium properties in great details. The precise calculations require the systematic resummation and consistently including medium modifications. Specifically, we discuss the calculations of jet shapes and cross sections in proton-proton and lead-lead collisions at the LHC using soft-collinear effective theory, with Glauber gluon interactions in the medium. In the end we present the comparison between our calculations and the recent measurements at the LHC with very good agreement. We conclude that precise jet modification studies in heavy ion collisions has been initiated.

   hep-phnucl-thPoS(2016)·0 citations
9. 09*

   Magnetic Moments of Baryons containing all heavy quarks in Quark-Diquark Model

   Kaushal Thakkar🇮🇳 · Ajay Majethiya🇮🇳 · P. C. Vinodkumar🇮🇳

   The triply heavy flavour baryons are studied using the Quark-diquark description of the three-body system. The confinement potential for present study of triply heavy flavour baryons is assumed as coulomb plus power potential with power index $\nu$. We have solved Schrodinger equation numerically to calculate the masses of triply heavy flavour baryons. The masses and magnetic moments of triply heavy flavour baryons are computed for different power indices, $\nu$, starting from 0.4 to 1.0. The predicted masses and magnetic moments are in good agreement with other theoretical predictions.

   hep-phEur.Phys.J.Plus(2016)·46 citations
10. 10*

    Discovering and profiling Z' bosons using asymmetry observables in top quark pair production with the lepton-plus-jets final state at the LHC

    Lucio Cerrito🇮🇹 · Declan Millar🇬🇧 · Stefano Moretti🇬🇧 · Francesco Spanò🇬🇧

    The sensitivity of top quark pair production at the Large Hadron Collider to the presence and nature of an underlying Z' boson is studied, accounting for six-fermion decay with full tree-level Standard Model ttbar interference and all intermediate particles allowed off-shell. Focus is placed on the lepton-plus-jets final state, emulating experimental conditions, including kinematic requirements and top quark pair reconstruction in the presence of missing transverse energy and combinatorial ambiguity in jet-top assignment. Considering a resonance with mass of 4 TeV, and assuming 300 inverse fb of proton-proton collisions with a centre of mass energy of 13 TeV data, a combination of forward-backward and top polarisation asymmetries are shown to distinguish Z' embedded by different classes of Grand-Unified-Theory-inspired models. In combination with the differential cross section, they may be used to increase the significance of the signal when tested against the Standard Model, as shown using a likelihood-based statistical test.

    hep-ph13 citations
11. 11*

    Minimal Mirror Twin Higgs

    Riccardo Barbieri🇮🇹 · Lawrence J. Hall🇺🇸 · Keisuke Harigaya🇺🇸

    In a Mirror Twin World with a maximally symmetric Higgs sector the little hierarchy of the Standard Model can be significantly mitigated, perhaps displacing the cutoff scale above the LHC reach. We show that consistency with observations requires that the Z2 parity exchanging the Standard Model with its mirror be broken in the Yukawa couplings. A minimal such effective field theory, with this sole Z2 breaking, can generate the Z2 breaking in the Higgs sector necessary for the Twin Higgs mechanism. The theory has constrained and correlated signals in Higgs decays, direct Dark Matter Detection and Dark Radiation, all within reach of foreseen experiments, over a region of parameter space where the fine-tuning for the electroweak scale is 10-50%. For dark matter, both mirror neutrons and a variety of self-interacting mirror atoms are considered. Neutrino mass signals and the effects of a possible additional Z2 breaking from the vacuum expectation values of B-L breaking fields are also discussed.

    hep-phastro-ph.COhep-exJHEP(2016)·110 citations
12. 12*

    $J/\psi$ Production in Polarized and Unpolarized $ep$ Collision and Sivers and $\cos 2\varphi$ Asymmetries

    Asmita Mukherjee🇮🇳 · Sangem Rajesh🇮🇳

    We calculate the Sivers and $\cos 2\varphi$ azimuthal asymmetries in $J/\psi$ production in polarized and unpolarized semi-inclusive $ep$ collision respectively, using the formalism based on transverse momentum dependent parton distributions (TMDs). Non-relativistic QCD based color octet model is employed for calculating the $J/\psi$ production rate. The Sivers asymmetry in this process directly probes the gluon Sivers function. The estimated Sivers asymmetry at $z=1$ is negative which is in good agreement with COMPASS data. We also investigate the effect of TMD evolution on the Sivers asymmetry. The $\cos 2\varphi$ asymmetry is sizable and probes the linearly polarized gluon distribution in an unpolarized proton.

    hep-phEPJC(2017)·70 citations
13. 13*

    Constraints on small-field axion inflation

    Tatsuo Kobayashi🇯🇵 · Akane Oikawa🇯🇵 · Naoya Omoto🇯🇵 · Hajime Otsuka🇯🇵 · Ikumi Saga🇯🇵

    We study general class of small-field axion inflations which are the mixture of polynomial and sinusoidal functions suggested by the natural and axion monodromy inflations. The axion decay constants leading to the successful axion inflations are severely constrained in order not to spoil the Big-Bang nucleosynthesis and overproduce the isocurvature perturbation originating from the QCD axion. We in turn find that the cosmologically favorable axion decay constants are typically of order the grand unification scale or the string scale which is consistent with the prediction of closed string axions.

    hep-phastro-ph.COhep-thPRD(2017)·5 citations
14. 14*

    Mini-Proceedings, 18th meeting of the Working Group on Radiative Corrections and MC Generators for Low Energies

    H. Czyż · S. Eidelman · F. Ignatov · A. Keshavarzi · A. Kupsc · V. E. Lyubovitskij · P. Masjuan · A. Nyffeler · G. Pancheri · E. Tomasi-Gustafsson · G. Venanzoni

    The mini-proceedings of the 18${}^{\mathrm{th}}$ Meeting of the "Working Group on Radiative Corrections and MonteCarlo Generators for Low Energies" held in Frascati, 19${}^{\mathrm{th}}$ - 20${}^{\mathrm{st}}$ May, are presented. These meetings, started in 2006, have as aim to bring together experimentalists and theoreticians working in the fields of meson transition form factors, hadronic contributions to the anomalous magnetic moment of the leptons, and the effective fine structure constant. The development of MonteCarlo generators and Radiative Corrections for precision $e^{+}{e}^{-}$ and $\tau$-lepton physics are also covered, with emphasis on meson production. At this workshop, a documentary entitled {\it Bruno Touschek with AdA in Orsay} commemorating the first observation of electron-positron collisions in a laboratory was also presented. With this edition, the working group reaches 10 years of continuous activities.

    hep-phhep-exnucl-exnucl-th0 citations
15. 15*

    Search for $Z^{\prime }$, vacuum (in)stability and hints of high-energy structures

    Elena Accomando🇬🇧 · Claudio Coriano🇮🇹 · Luigi Delle Rose🇬🇧 · Juri Fiaschi🇬🇧 · Carlo Marzo🇮🇹 · Stefano Moretti🇬🇧

    We study the high-energy behaviour of a class of anomaly-free abelian extensions of the Standard Model. We focus on the interplay among the phenomenological characterisation of the model and the use of precise renormalisation group methods. Using as boundary conditions regions of the parameter space at the verge of current LHC probe, interesting unification patterns emerge linked to thresholds belonging to a SO(10) grand unification theory (GUT). We stress how the evolution of the mixing between the two abelian factors may provide a valuable tool to address the candidate high-energy embedding. The emerging unification scenarios are then challenged to be perturbative and to allow for a stable vacuum.

    hep-phEPJ Web Conf.(2016)·2 citations
16. 16*

    Micro-orbits in a many-branes model and deviations from $1/r^2$ Newton's law

    A. Donini🇪🇸 · S. G. Marimón🇪🇸

    We consider a 5-dimensional model with geometry $\mathcal{M}={\mathcal{M}}_4\times {\mathcal{S}}_1$, with compactification radius $R$. The Standard Model particles are localized onto a brane located at y=0, with identical branes localized at different points in the extra dimension. Objects located on our brane can orbit around objects located on a brane at a distance $d=y/R$, with an orbit and a period significantly different from the standard Newtonian ones. We study the kinematical properties of the orbits, finding that it is possible to distinguish one motion from the other in a large region of the initial conditions parameter space. This is a warm-up to study if a SM-like mass distribution on one (or more) distant brane(s) may represent a possible dark matter candidate. After using the same technique to the study of orbits of objects lying on the same brane ($d=0$), we apply this method to detect generic deviations from the inverse-square Newton's law. We propose a possible experimental setup to look for departures from Newtonian motion in the micro-world, finding that an order of magnitude improvement on present bounds can be attained at the 95% CL under reasonable assumptions.

    hep-phgr-qcEPJC(2016)·10 citations
17. 17*

    The Revival of Kaon Flavour Physics

    Andrzej J. Buras🇩🇪

    After years of silence we should witness in the rest of this decade and in the next decade the revival of kaon flavour physics. This is not only because of the crucial measurements of the branching ratios for the rare decays $K^{+}\to {\pi }^{+}\nu \bar{\nu }$ and $K_L\to {\pi }^0\nu \bar{\nu }$ by NA62 and KOTO that being theoretically clean and very sensitive to new physics (NP) could hint for new phenomena even beyond the reach of the LHC without any significant theoretical uncertainties. Indeed simultaneously the advances in the calculations of perturbative and in particular non-perturbative QCD effects in ${\epsilon }^{\prime }/\epsilon$, ${\epsilon }_K$, $\Delta M_K$, $K_L\to {\mu }^{+}{\mu }^{-}$ and $K_L\to {\pi }^0{\ell }^{+}{\ell }^{-}$ will increase the role of these observables in searching for NP. In fact the hints for NP contributing to ${\epsilon }^{\prime }/\epsilon$ have been already signalled last year through improved estimates of hadronic matrix elements of QCD and electroweak penguin operators $Q_6$ and $Q_8$ by lattice QCD and large $N$ dual QCD approach. This talk summarizes in addition to this new flavour anomaly the present highlights of this field including some results from concrete NP scenarios.

    hep-phhep-exhep-latEPJ Web Conf.(2016)·9 citations
18. 18*

    Properties of vector mesons in four pseudoscalars electroproduction

    G. Toledo Sanchez🇲🇽

    Vector mesons and the $W$ gauge boson share some common features, such as the spin and a very short lifetime. The electromagnetic properties of the $W$ are linked to its gauge nature and thus a big effort has been devoted to measure them, while accounting for its instability. In this work, we elaborate on how these ideas can be translated to study vector mesons. We focus in the unstable property of such states and the restrictions from electromagnetic gauge invariance, describing the differences and similarities. Then, we describe the four pseudoscalars electroproduction as an analog to the $e^{+}{e}^{-}\to 4fermions$ process, used to study the electromagnetic properties of the $W$ boson. We point out that the current experimental capabilities are reaching the possibility to measure the magnetic dipole moment of light vector mesons.

    hep-phnucl-thJ.Phys.Conf.Ser.(2016)·0 citations
19. 19*

    Wigner, Husimi and GTMD distributions in the Color Glass Condensate

    Yoshikazu Hagiwara🇯🇵 · Yoshitaka Hatta🇯🇵 · Takahiro Ueda🇳🇱

    We study the phase space distributions of gluons inside a nucleon/nucleus in the small-$x$ regime including the gluon saturation effect. This can be done by using the relation between the gluon Wigner distribution and the dipole S-matrix at small-$x$, the latter satisfies the Balitsky-Kovchegov (BK) equation. By efficiently solving the BK equation with impact parameter dependence, we compute the Wigner, Husimi and generalized TMD (GTMD) distributions in the saturation regime. We also investigate the elliptic angular dependence of these distributions which has been recently shown to be measurable in DIS experiments.

    hep-phPRD(2016)·69 citations
20. 20*

    The problem of kinematic mass corrections for unpolarized semi-inclusive deep inelastic scattering

    Ekaterina Christova🇧🇬 · Elliot Leader🇬🇧

    Miraculously, target mass corrections for inclusive deep inelastic scattering can be calculated exactly. On the contrary, there does not exist a consistent derivation of kinematic hadron mass corrections for semi-inclusive deep inelastic scattering (SIDIS). Recently this has become of topical interest, since there is a significant difference between the measured HERMES and COMPASS pion and kaon multiplicities, which cannot be explained as a consequence of evolution in $Q^2$, and it has been suggested that the difference can be understood if kinematic hadron mass corrections are taken into account. We explain why this argument is incorrect.

    hep-phPRD(2016)·7 citations
21. 21*

    Leptogenesis in a $\Delta (27)\times SO(10)$ SUSY GUT

    Fredrik Björkeroth🇬🇧 · Francisco J. de Anda🇲🇽 · Ivo de Medeiros Varzielas🇬🇧 · Stephen F. King🇬🇧

    Although $SO(10)$ Supersymmetric (SUSY) Grand Unification Theories (GUTs) are very attractive for neutrino mass and mixing, it is often quite difficult to achieve successful leptogenesis from the lightest right-handed neutrino $N_1$ due to the strong relations between neutrino and up-type quark Yukawa couplings. We show that in a realistic model these constraints are relaxed, making $N_1$ leptogenesis viable. To illustrate this, we calculate the baryon asymmetry of the Universe $Y_B$ from flavoured $N_1$ leptogenesis in a recently proposed $\Delta (27)\times SO(10)$ SUSY GUT. The flavoured Boltzmann equations are solved numerically, and comparison with the observed $Y_B$ places constraints on the allowed values of right-handed neutrino masses and neutrino Yukawa couplings. The flavoured $SO(10)$ SUSY GUT is not only fairly complete and predictive in the lepton sector, but can also explain the BAU through leptogenesis with natural values in the lepton sector albeit with some tuning in the quark sector.

    hep-phJHEP(2017)·27 citations
22. 22*

    Cumulants and nonlinear response of high $p_T$ harmonic flow at $\sqrt{s_{NN}}=5.02$ TeV

    Jacquelyn Noronha-Hostler🇺🇸 · Barbara Betz🇩🇪 · Miklos Gyulassy🇺🇸 · Matthew Luzum🇧🇷 · Jorge Noronha🇧🇷 · Israel Portillo🇺🇸 · Claudia Ratti🇺🇸

    Event-by-event fluctuations caused by quantum mechanical fluctuations in the wave function of colliding nuclei in ultrarelativistic heavy ion collisions were recently shown to be necessary for the simultaneous description of $R_{AA}$ as well as the elliptic and triangular flow harmonics at high $p_T$ in PbPb collisions at the Large Hadron Collider. In fact, the presence of a finite triangular flow as well as cumulants of the flow harmonic distribution that differ from the mean are only possible when these event-by-event fluctuations are considered. In this paper we combine event-by-event viscous hydrodynamics and jet quenching to make predictions for high $p_T$ $R_{AA}$, $v_2\{2\}$, $v_3\{2\}$, and $v_2\{4\}$ in PbPb collisions at $\sqrt{s_{NN}}=5.02$ TeV. With an order of magnitude larger statistics we find that high $p_T$ elliptic flow does not scale linearly with the soft elliptical flow, as originally thought, but has deviations from perfectly linear scaling. A new experimental observable, which involves the difference between the ratio of harmonic flow cumulants at high and low $p_T$, is proposed to investigate the fluctuations of high $p_T$ flow harmonics and measure this nonlinear response. By varying the path length dependence of the energy loss and the viscosity of the evolving medium we find that $R_{AA}(p_T)$ and $v_2\{2\}(p_T)$ strongly depend on the choice for the path length dependence of the energy loss, which can be constrained using the new LHC run 2 data.

    ↳ nucl-thhep-phnucl-exPRC(2017)·86 citations
23. 23*

    Centrality dependence of chemical freeze-out parameters from net-proton and net-charge fluctuations using hadron resonance gas model

    Rama Prasad Adak🇮🇳 · Supriya Das🇮🇳 · Sanjay K. Ghosh🇮🇳 · Rajarshi Ray🇮🇳 · Subhasis Samanta🇮🇳

    We estimate chemical freeze-out parameters in HRG and EVHRG model by fitting the experimental information of net-proton and net-charge fluctuations measured in Au + Au collisions by the STAR collaboration at RHIC. We observe that chemical freeze-out parameters obtained from lower and higher order fluctuations are though almost same for $\sqrt{s_{NN}}>27$ GeV, tend to deviate from each other at lower $\sqrt{s_{NN}}$. Moreover, these separations increase with decrease of $\sqrt{s_{NN}}$ and for a fixed $\sqrt{s_{NN}}$ increase towards central collisions. Furthermore, we observe an approximate scaling behaviour of $({\mu }_B/T)/({\mu }_B/T{)}_{central}$ with $(N_{part})/(N_{part}{)}_{central}$ for the parameters estimated from lower order fluctuations for 11.5 GeV $\le \sqrt{s_{NN}}\le$ 200 GeV. Scaling is violated for the parameters estimated from higher order fluctuations for $\sqrt{s_{NN}}=11.5$ and 19.6 GeV. It is observed that the chemical freeze-out parameter, which can describe ${\sigma }^2/M$ of net-proton very well in all energies and centralities, can not describe the $s\sigma$ equally well and vice versa.

    ↳ nucl-thhep-phnucl-exPRC(2017)·24 citations
24. 24*

    Proton-proton hollowness at the LHC from inverse scattering

    Enrique Ruiz Arriola🇪🇸 · Wojciech Broniowski🇵🇱

    Parameterizations of the pp scattering data at the LHC collision energies indicate a hollow in the inelasticity profile of the pp interaction, with less absorption for head-on collisions than at a non-zero impact parameter. We show that some qualitatively unnoticed features may be unveiled by a judicious application of the inverse scattering problem in the eikonal approximation and interpre- tation within an optical potential model. The hollowness effect is magnifed in a 3D picture of the optical potential, and will presumably be enhanced at yet higher energies. Moreover, in 3D it sets in at much smaller energies than at the LHC. We argue that hollowness in the impact parameter is a quantum effect, relying on the build-up of the real part of the eikonal scattering phase and its possible passage through $\pi /2$. We also show that it precludes models of inelastic collisions where inelasticity is obtained by naive folding of partonic densities.

    ↳ nucl-thhep-exhep-phPRD(2017)·29 citations
25. 25*

    Nuclear structure calculations for two-neutrino double-beta decay

    P. Sarriguren🇪🇸 · O. Moreno🇺🇸 · E. Moya de Guerra🇪🇸

    We study the two-neutrino double-beta decay in 76Ge, 116Cd, 128Te, 130Te, and 150Nd, as well as the two Gamow-Teller branches that connect the double-beta decay partners with the states in the intermediate nuclei. We use a theoretical microscopic approach based on a deformed selfconsistent mean field with Skyrme interactions including pairing and spin-isospin residual forces, which are treated in a proton-neutron quasiparticle random-phase approximation. We compare our results for Gamow-Teller strength distributions with experimental information obtained from charge-exchange reactions. We also compare our results for the two-neutrino double-beta decay nuclear matrix elements with those extracted from the measured half-lives. Both single-state and low-lying-state dominance hypotheses are analyzed theoretically and experimentally making use of recent data from charge-exchange reactions and beta decay of the intermediate nuclei.

    ↳ nucl-thhep-phAdv.High Energy Phys.(2016)·6 citations
26. 26*

    Heavy quark dynamics in QCD matter

    Santosh K. Das🇮🇹 · Francesco Scardina🇮🇹 · Salvatore Plumari🇮🇹 · Vincenzo Greco🇮🇹

    Simultaneous description of heavy quark nuclear suppression factor $R_{AA}$ and the elliptic flow $v_2$ is a top challenge for all the existing models. We highlight how the temperature dependence of the energy loss/transport coefficients is responsible to address a large part of such a puzzle along with the the full solution of the Boltzmann collision integral for the momentum evolution of heavy quark. We consider four different models to evaluate the temperature dependence of drag coefficients of the heavy quark in the QGP. We have also highlighted the heavy quark dynamics in the presence of an external electromagnetic field which develops a sizable heavy quark directed flow, $v_1(y)$, can be measurable at LHC.

    ↳ nucl-thhep-phJ.Phys.Conf.Ser.(2017)·1 citation
27. 27*

    Some aspects on four quarks recombination

    G. Toledo Sanchez🇲🇽 · I. A. Toledano Juarez🇲🇽

    We have performed a 3-D Monte Carlo simulation of a system composed of two identical light quarks ($qq$) and two identical antiquarks ($\bar{Q}\bar{Q}$) and determined whether it is energetically more favorable to form a tetraquark or two mesons, as a function of the interparticle separation distance which, for a fixed number of particles, can be identified as a particle density. In this proceedings, we highlight the main results and elaborate on the implications in properties like the correlation function for two-mesons and characterize the isolated diquark correlation function. We analize the four-body potential evolution and exhibit its linear behavior as a function of the invariant distance. We track the dynamical flipping among configurations to determine the recombination probability, exhibiting the importance of the tetraquark state.

    ↳ nucl-thhep-phJ.Phys.Conf.Ser.(2016)·0 citations
28. 28*

    Quark and Gluon Production from a Boost-invariantly Expanding Color Electric Field

    Hidetoshi Taya🇯🇵

    Particle production from an expanding classical color electromagnetic field is extensively studied, motivated by the early stage dynamics of ultra-relativistic heavy ion collisions. We develop a formalism at one-loop order to compute the particle spectra by canonically quantizing quark, gluon and ghost fluctuations under the presence of such an expanding classical color background field; the canonical quantization is done in the $\tau$-$\eta$ coordinates in order to take into account manifestly the expanding geometry. As a demonstration, we model the expanding classical color background field by a boost-invariantly expanding homogeneous color electric field with lifetime $T$, for which we obtain analytically the quark and gluon production spectra by solving the equations of motion of QCD non-perturbatively with respect to the color electric field. In this paper we study (i) finite lifetime effect which is found to modify significantly the particle spectra from those expected from the Schwinger formula; (ii) the difference between the quark and gluon production; and (iii) the quark mass dependence of the production spectra. Implications of these results to ultra-relativistic heavy ion collisions are also discussed.

    ↳ nucl-thhep-phPRD(2017)·13 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.