Tue·Jan 17, 2017Tuesday·January 17, 2017

1. 01*

   Inflation due to non-minimal coupling of $f(R)$ gravity to a scalar field

   Romy H. S. Budhi🇮🇩

   In this work we investigate a inflationary scenario generated by a large scalar field $\varphi$ that non-minimally couples to a $f(R)$ modified gravity model. For a Starobinsky's like model, it is found that along a particular flat direction, the scalar potential takes a simple form $V=(M_p^4/4)[V(\varphi )/\alpha (\varphi {)}^2]$ where $\alpha (\varphi )$ is a non-minimal coupling to Ricci scalar $R$ in the model. The inflation, therefore, is effectively represented as a single field inflaton scenario. For a specific example, such as a scalar potential $V(\varphi )={\mu }_1{\varphi }^2+{\mu }_2{\varphi }^4$, we found that the predictions match nicely in the $1\sigma$ confidence level of \textit{Plank} TT, TE, EE+lowP combination data of Planck 2015 CMB data for $0<{\mu }_3\le 100$, where ${\mu }_3:=|{\mu }_1|/({\mu }_2{M}_p^2)$. For example, taking ${\mu }_3=0.01$ the scalar-to-tensor ratio $r=0.0004$ and and spectral index $n_s=0.96985$ for $N_{\ast }=50$ while taking ${\mu }_3=100.0$ produces $r=0.03$ and $n_s=0.96359$ for $N_{\ast }=60$.

   hep-phgr-qc3 citations
2. 02*

   Hidden-charm pentaquarks and their hidden-bottom and $B_c$-like partner states

   Jing Wu🇨🇳 · Yan-Rui Liu🇨🇳 · Kan Chen🇨🇳 · Xiang Liu🇨🇳 · Shi-Lin Zhu🇨🇳

   In the framework of the color-magnetic interaction, we have systematically studied the mass splittings of the possible hidden-charm pentaquarks $qqqc\bar{c}$ ($q=u,d,s$) where the three light quarks are in a color-octet state. We find that i) the LHCb $P_c$ states fall in the mass region of the studied system; ii) most pentaquarks should be broad states since their $S$-wave open-charm decays are allowed while the lowest state is the $J^P={\frac{1}{2}}^{-}$ $\Lambda$-like pentaquark with probably the suppressed ${\eta }_c\Lambda$ decay mode only; and iii) the $J^P={\frac{5}{2}}^{-}$ states do not decay through $S$-wave and their widths are not so broad. The masses and widths of the two LHCb $P_c$ baryons are compatible with such pentaquark states. We also explore the hidden-bottom and $B_c$-like partners of the hidden-charm states and find the possible existence of the pentaquarks which are lower than the relevant hadronic molecules.

   hep-phhep-exPRD(2017)·63 citations
3. 03*

   The ${\Lambda }_b\to \Lambda (\to p{\pi }^{-}){\mu }^{+}{\mu }^{-}$ decay in the aligned two-Higgs-doublet model

   Quan-Yi Hu🇨🇳 · Xin-Qiang Li🇨🇳 · Ya-Dong Yang🇨🇳

   The rare baryonic decay ${\Lambda }_b\to \Lambda (\to p{\pi }^{-}){\mu }^{+}{\mu }^{-}$ provides valuable complementary information compared to the corresponding mesonic $b\to s{\mu }^{+}{\mu }^{-}$ transition. In this paper, using the latest high-precision lattice QCD calculation of the ${\Lambda }_b\to \Lambda$ transition form factors, we study this interesting decay within the aligned two-Higgs-doublet model, paying particularly attention to effects of the chirality-flipped operators generated by the charged scalars. In order to extract the full set of angular coefficients in this decay, we consider the following ten angular observables that can be derived from the analysis of the subsequent parity-violating $\Lambda \to p{\pi }^{-}$ decay: the differential branching fraction $\mathrm{d}\mathcal{B}/\mathrm{d}{q}^2$, the longitudinal polarization fraction $F_L$, the lepton-, hadron- and combined lepton-hadron-side forward-backward asymmetries $A_{\mathrm{FB}}^{\ell }$, $A_{\mathrm{FB}}^{\Lambda }$ and $A_{\mathrm{FB}}^{\ell \Lambda }$, as well as the other five asymmetry observables $Y_i$~($i=2,3s,3sc,4s,4sc$). Detailed numerical comparisons are made between the SM and NP values for these angular observables. It is found that, under the constraints from the inclusive $B\to X_s\gamma$ branching fraction and the latest global fit results of $b\to s\ell \ell$ data, the contributions of right-handed semileptonic operators $O_{9,10}^{\prime }$, besides reconciling the $P_5^{\prime }$ anomaly observed in $B^0\to K^{\ast 0}{\mu }^{+}{\mu }^{-}$ decay, could also enhance the values of $\mathrm{d}\mathcal{B}/\mathrm{d}{q}^2$ and $A_{\mathrm{FB}}^{\ell }$ in the bin $[15,20]{\mathrm{GeV}}^2$, leading to results consistent with the current LHCb measurements.

   hep-phhep-exEPJC(2017)·19 citations
4. 04*

   Quark Diagram Analysis of Bottom Meson Decays Emitting Pseudoscalar and Vector Mesons

   Maninder Kaur🇮🇳 · Supreet Pal Singh🇮🇳 · R. C. Verma🇮🇳

   This paper presents the two body weak nonleptonic decays of B mesons emitting pseudoscalar (P) and vector (V) mesons within the framework of the diagrammatic approach at flavor SU(3) symmetry level. Using the decay amplitudes, we are able to relate the branching fractions of B PV decays induced by both b c and b u transitions, which are found to be well consistent with the measured data. We also make predictions for some decays, which can be tested in future experiments.

   hep-phPhys.Part.Nucl.Lett.(2018)·1 citation
5. 05*

   Minimal renormalizable simplified dark matter model with a pseudoscalar mediator

   Seungwon Baek🇰🇷 · P. Ko🇰🇷 · Jinmian Li🇰🇷

   We consider a minimal renormalizable and gauge invariant dark matter (DM) model, in which the singlet fermion DM has only axial couplings to a new pseudoscalar mediator. The mixing between the pseudoscalar mediator and the standard model (SM) Higgs boson induces the interactions between the DM and SM particles. The DM candidate in this model can provide the correct thermal relic density and evades all direct detections, while it can produce observable signals in indirect detection experiments due to its large annihilation cross section. A comparative study for DM phenomenology at the LHC is conducted for models with scalar mediators that have either scalar or pseudoscalar couplings to SM particles and the DM. We find that the three scenarios have distinguishable features in scalar decay branching ratio, DM pair production cross section as well as the signal reaches at the LHC. The LHC searches for some visible signals related to the scalar sector are also discussed.

   hep-phhep-exPRD(2017)·58 citations
6. 06*

   Evolution of Chirality-odd Twist-3 Fragmentation Functions

   J.P. Ma🇨🇳 · G.P. Zhang🇨🇳

   We derive the complete set of evolutions of chirality-odd twist-3 fragmentation functions at one-loop level. There are totally nine real twist-3 fragmentation functions, among which seven are independent. The renormalization-scale dependence of the nine functions has an important implication for studies of single transverse-spin asymmetries. We find that the evolutions of the three complex fragmentation functions defined by quark-gluon-quark operator are mixed with themselves. There is no mixing with the fragmentation functions defined only with bilinear quark field operators. In the large-$N_c$ limit the evolutions of the three complex fragmentation functions are simplified and reduced to six homogenous equations.

   hep-phPLB(2017)·6 citations
7. 07*

   Single top theory

   Francesco Tramontano🇮🇹

   I breafly discuss very recent progress in the theoretical description of Standard Model single top production at hadron colliders.

   hep-ph0 citations
8. 08*

   Elliptic Flow in Small Systems due to Elliptic Gluon Distributions?

   Yoshikazu Hagiwara🇯🇵 · Yoshitaka Hatta🇯🇵 · Bo-Wen Xiao🇨🇳 · Feng Yuan🇺🇸

   We investigate the contributions from the so-called elliptic gluon Wigner distributions to the rapidity and azimuthal correlations of particles produced in high energy $pA$ collisions by applying the double parton scattering mechanism. We compute the `elliptic flow' parameter $v_2$ as a function of the transverse momentum and rapidity, and find qualitative agreement with experimental observations. This shall encourage further developments with more rigorous studies of the elliptic gluon distributions and their applications in hard scattering processes in $pp$ and $pA$ collisions.

   hep-phPLB(2017)·43 citations
9. 09*

   Fuchsia: a tool for reducing differential equations for Feynman master integrals to epsilon form

   O. Gituliar🇩🇪 · V. Magerya🇩🇪

   We present $\text{Fuchsia}$ $-$ an implementation of the Lee algorithm, which for a given system of ordinary differential equations with rational coefficients ${\partial }_x\mathbf{f}(x,ϵ)=\mathbb{A}(x,ϵ)\mathbf{f}(x,ϵ)$ finds a basis transformation $\mathbb{T}(x,ϵ)$, i.e., $\mathbf{f}(x,ϵ)=\mathbb{T}(x,ϵ)\mathbf{g}(x,ϵ)$, such that the system turns into the epsilon form: ${\partial }_x\mathbf{g}(x,ϵ)=ϵ\mathbb{S}(x)\mathbf{g}(x,ϵ)$, where $\mathbb{S}(x)$ is a Fuchsian matrix. A system of this form can be trivially solved in terms of polylogarithms as a Laurent series in the dimensional regulator $ϵ$. That makes the construction of the transformation $\mathbb{T}(x,ϵ)$ crucial for obtaining solutions of the initial equations. In principle, $\text{Fuchsia}$ can deal with any regular systems, however its primary task is to reduce differential equations for Feynman master integrals. It ensures that solutions contain only regular singularities due to the properties of Feynman integrals.

   hep-phmath-phmath.CAmath.MPComput.Phys.Commun.(2017)·183 citations
10. 10*

    Exploring pseudo-Nambu--Goldstone bosons by stimulated photon colliders in the mass range 0.1~eV to 10~keV

    Kensuke Homma🇯🇵 · Yuichi Toyota🇯🇵

    Searching for pseudo-Nambu--Goldstone bosons (pNGBs) in weak-coupling domains is crucial for understanding the dark components in the universe. We propose searching for pNGBs coupled to two photons in the mass range from 0.1~eV to 10~keV. This could provide opportunities to test string-theory-based pNGBs beyond the GUT scale $M\sim 10^{16}$~GeV included in the weak coupling proportional to $M^{-1}$. We provide formulae that are applicable to photon--photon scattering via a pNGB resonance exchange with a stimulation process in an asymmetric head-on photon--photon collider by mixing three laser pulses in laboratory experiments. We discuss the quantum electrodynamic effects on the pNGB exchange in the same mass--coupling domain as a background process from the standard model. We find that a large unexplored mass--coupling domain is accessible by combining existing laser facilities, including free-electron lasers.

    hep-phgr-qchep-exPTEP(2017)·17 citations
11. 11*

    Analysis of the $QQ\bar{Q}\bar{Q}$ tetraquark states with QCD sum rules

    Zhi-Gang Wang🇨🇳

    In this article, we study the $J^{PC}=0^{++}$ and $2^{++}$ $QQ\bar{Q}\bar{Q}$ tetraquark states with the QCD sum rules, and obtain the predictions $M_{X(cc\bar{c}\bar{c},0^{++})}=5.99\pm 0.08\mathrm{GeV}$, $M_{X(cc\bar{c}\bar{c},2^{++})}=6.09\pm 0.08\mathrm{GeV}$, $M_{X(bb\bar{b}\bar{b},0^{++})}=18.84\pm 0.09\mathrm{GeV}$ and $M_{X(bb\bar{b}\bar{b},2^{++})}=18.85\pm 0.09\mathrm{GeV}$, which can be confronted to the experimental data in the future. Furthermore, we illustrate that the diquark-antidiquark type tetraquark state can be taken as a special superposition of a series of meson-meson pairs and embodies the net effects.

    hep-phEPJC(2017)·161 citations
12. 12*

    Gluonic Lorentz violation and chiral perturbation theory

    J. P. Noordmans🇵🇹

    By applying chiral-perturbation-theory methods to the QCD sector of the Lorentz-violating Standard-Model Extension, we investigate Lorentz violation in the strong interactions. In particular, we consider the CPT-even pure-gluon operator of the minimal Standard-Model Extension. We construct the lowest-order chiral effective Lagrangian for three as well as two light quark flavors. We develop the power-counting rules and construct the heavy-baryon chiral-perturbation-theory Lagrangian, which we use to calculate Lorentz-violating contributions to the nucleon self energy. Using the constructed effective operators, we derive the first stringent limits on many of the components of the relevant Lorentz-violating parameter. We also obtain the Lorentz-violating nucleon-nucleon potential. We suggest that this potential may be used to obtain new limits from atomic-clock or deuteron storage-ring experiments.

    hep-phnucl-thPRD(2017)·18 citations
13. 13*

    Probing the gauge symmetry breaking of the early universe in 3-3-1 models and beyond by gravitational waves

    Fa Peng Huang🇨🇳 · Xinmin Zhang🇨🇳

    Taking the 3-3-1 models (with $SU(3{)}_c\otimes SU(3{)}_L\otimes U(1{)}_Y$ gauge group) as examples, we study that a class of new physics models with extended gauge group could undergo one or several first-order phase transitions associated with the spontaneously symmetry breaking processes during the evolution of the universe, which can produce detectable phase transition gravitational wave (GW) signals at future GW experiments, such as LISA, BBO, DECIGO, SKA and aLIGO. These GW signals can provide new sources of GWs with different peak frequencies, and can be used to probe the evolution history of the universe.

    hep-phPLB(2019)·58 citations
14. 14*

    Investigating the impact of the gluon saturation effects on the momentum transfer distributions for the exclusive vector meson photoproduction in hadronic collisions

    V. P. Goncalves🇧🇷 · F. S. Navarra🇧🇷 · D. Spiering🇧🇷

    The exclusive vector meson production cross section is one of the most promising observables to probe the high energy regime of the QCD dynamics. In particular, the squared momentum transfer ($t$) distributions are an important source of information about the spatial distribution of the gluons in the hadron and about fluctuations of the color fields. In this paper we complement previous studies on exclusive vector meson photoproduction in hadronic collisions presenting a comprehensive analysis of the $t$ - spectrum measured in exclusive $\rho$, $\varphi$ and $J/\Psi$ photoproduction in $pp$ and $PbPb$ collisions at the LHC. We compute the differential cross sections taking into account gluon saturation effects and compare the predictions with those obtained in the linear regime of the QCD dynamics. Our results show that gluon saturation suppresses the magnitude of the cross sections and shifts the position of the dips towards smaller values of $t$.

    hep-phhep-exnucl-exnucl-thPLB(2017)·25 citations
15. 15*

    Unified Models of Neutrinos, Flavour and CP Violation

    S. F. King🇬🇧

    Recent data from neutrino experiments gives intriguing hints about the mass ordering, the CP violating phase and non-maximal atmospheric mixing. There seems to be a (one sigma) preference for a normal ordered (NO) neutrino mass pattern, with a CP phase $\delta =-100^{\circ }\pm 50^{\circ }$, and (more significantly) non-maximal atmospheric mixing. Global fits for the NO case yield lepton mixing angle one sigma ranges: ${\theta }_{23}\approx 41.4^{\circ }\pm 1.6^{\circ }$, ${\theta }_{12}\approx 33.2^{\circ }\pm 1.2^{\circ }$, ${\theta }_{13}\approx 8.45^{\circ }\pm 0.15^{\circ }$. Cosmology gives a limit on the total of the three masses to be below about $0.23$ eV, favouring hierarchical neutrino masses over quasi-degenerate masses. Given such experimental advances, it seems an opportune moment to review the theoretical status of attempts to explain such a pattern of neutrino masses and lepton mixing, focussing on approaches based on the four pillars of: {\em predictivity}, {\em minimality}, {\em robustness} and {\em unification}. {\em Predictivity} can result from various mixing sum rules whose status is reviewed. {\em Minimality} can follow from the type I seesaw mechanism, including constrained sequential dominance of right-handed (RH) neutrinos, and the littlest seesaw model. {\em Robustness} requires enforcing a discrete CP and non-Abelian family symmetry, spontaneously broken by flavons with the symmetry preserved in a semi-direct way. {\em Unification} can account for all lepton and quark masses, mixing angles and CP phases, as in Supersymmetric Grand Unified Theories of Flavour, with possible string theory origin.

    hep-phPPNP(2017)·266 citations
16. 16*

    ${\Lambda }_c$ Semileptonic Decays in a Quark Model

    Md Mozammel Hussain🇺🇸 · Winston Roberts🇺🇸

    Hadronic form factors for semileptonic decay of the ${\Lambda }_c$ are calculated in a nonrelativistic quark model. The full quark model wave functions are employed to numerically calculate the form factors to all relevant orders in ($1/m_c$, $1/m_s$). The form factors obtained satisfy relationships expected from the heavy quark effective theory (HQET). The differential decay rates and branching fractions are calculated for transitions to the ground state and a number of excited states of $\Lambda$. The branching fraction of the semileptonic decay width to the total width of ${\Lambda }_c$ has been calculated and compared with other theoretical estimates and experimental results. The branching fractions for ${\Lambda }_c\to {\Lambda }^{\ast }{l}^{+}{\nu }_l\to \Sigma \pi l^{+}{\nu }_l$ and ${\Lambda }_c\to {\Lambda }^{\ast }{l}^{+}{\nu }_l\to N\bar{K}{l}^{+}{\nu }_l$ are also calculated. Apart from decays to the ground state $\Lambda$(1115), it is found that decays through the $\Lambda (1405)$ provide a significant portion of the branching fraction ${\Lambda }_c\to X_{s}l{\nu }_l$. A new estimate for $f=B({\Lambda }_c^{+}\to \Lambda l^{+}{\nu }_l)/B({\Lambda }_c^{+}\to X_s{l}^{+}{\nu }_l)$ is obtained.

    ↳ nucl-thhep-phPRD(2017)·18 citations
17. 17*

    Mean transverse momentum as a mass composition estimator of cosmic rays

    H. Hedayati Kh🇮🇷 · H. Hesari🇮🇷

    Determination of mass composition of high energy cosmic rays is one of the greatest challenge in modern astrophysics. All of previous methods for finding the mass composition of primary cosmic rays in a surface array at least require two independent measurements (e.g. muon and electron components) of extensive air showers (EAS). Here a new statistical parameter is introduced which can be used to determine the mass composition of vertical downward cosmic rays in a simple surface array. The most interesting thing about the new parameter is that it does not need two independent measurements and can be used in a simple surface array which does not have muon detectors.

    ↳ astro-ph.IMastro-ph.HEhep-ph0 citations
18. 18*

    Asteroseismic constraints on Asymmetric Dark Matter: Light particles with an effective spin-dependent coupling

    André Martins🇵🇹 · Ilídio Lopes🇵🇹 · Jordi Casanellas🇩🇪

    So far, direct detection searches have come empty handed in their quest for Dark Matter (DM). Meanwhile, asteroseismology arises as a complementary tool to study DM, as its accumulation in a star can enhance energy transport, by providing a conduction mechanism, producing significant changes in the stellar structure during the course of the star's evolution. The stellar core, particularly affected by the presence of DM, can be investigated through precise asteroseismic diagnostics. We modelled three stars including DM energy transport: the Sun, a slightly less massive and much older star, KIC 7871531 ($0.85M_{\odot }$, $9.41\text{Gyr}$), and a more massive and younger one, KIC 8379927 ($1.12M_{\odot }$, $1.82\text{Gyr}$). We considered both the case of Weakly Interactive Massive Particles, albeit with a low annihilation, and the case of Asymmetric DM for which the number of trapped particles in the star can be much greater. By analysing these models with asteroseismic separation ratios weighted towards the core, we found indications limiting the effective spin-dependent DM-proton coupling for masses of a few GeV. This independent result is very close to the most recent and most stringent direct detection DM constraints.

    ↳ astro-ph.SRastro-ph.COhep-phPRD(2017)·18 citations
19. 19*

    Magnetic Catalysis in Antiferromagnetic Films

    Christoph P. Hofmann🇲🇽

    We study the low-temperature behavior of antiferromagnets in two spatial dimensions that are subjected to a magnetic field oriented perpendicular to the staggered magnetization order parameter. The evaluation of the partition function is carried to two-loop order within the systematic effective Lagrangian technique. Low-temperature series that are valid in weak magnetic and staggered fields are derived for the pressure, staggered magnetization, and magnetization. Remarkably, at $T$=0, the staggered magnetization is enhanced by the magnetic field, implying that the phenomenon of magnetic catalysis also emerges in antiferromagnetic films.

    ↳ cond-mat.str-elhep-lathep-phPRB(2017)·8 citations
20. 20*

    The Contribution of Novel CP Violating Operators to the nEDM using Lattice QCD

    Rajan Gupta

    In this talk, we motivate the calculation of the matrix elements of novel CP violating operators, the quark EDM and the quark chromo EDM operators, within the nucleon state using lattice QCD. These matrix elements, combined with the bound on the neutron EDM, would provide stringent constraints on beyond the standard model physics, especially as the next generation of neutron EDM experiments reduce the current bound. We then present our lattice strategy for the calculation of these matrix elements, in particular we describe the use of the Schrödinger source method to reduce the calculation of the 4-point to 3-point functions needed to evaluate the quark chromo EDM contribution. We end with a status report on the quality of the signal obtained in the lattice calculations of the connected contributions to the quark chromo EDM operator and the pseudoscalar operator it mixes with under renormalization.

    ↳ hep-lathep-phEPJ Web Conf.(2017)·5 citations
21. 21*

    The pseudoscalar meson electromagnetic form factor at high $Q^2$ from full lattice QCD

    J. Koponen🇬🇧 · A. C. Zimermmane-Santos🇬🇧 · C. T. H. Davies🇬🇧 · G. P. Lepage🇺🇸 · A. T. Lytle🇬🇧

    We give an accurate determination of the vector (electromagnetic) form factor, $F(Q^2)$, for a light pseudoscalar meson up to squared momentum transfer $Q^2$ values of 6 ${\mathrm{GeV}}^2$ for the first time from full lattice QCD, including $u$, $d$, $s$ and $c$ quarks in the sea at multiple values of the lattice spacing. Our results show good control of lattice discretisation and sea quark mass effects. We study a pseudoscalar meson made of valence $s$ quarks but the qualitative picture obtained applies also to the $\pi$ meson, relevant to upcoming experiments at Jefferson Lab. We find that $Q^{2}F(Q^2)$ becomes flat in the region between $Q^2$ of 2 ${\mathrm{GeV}}^2$ and 6 ${\mathrm{GeV}}^2$, with a value well above that of the asymptotic perturbative QCD expectation, but well below that of the vector-meson dominance pole form appropriate to low $Q^2$ values. Our calculations show that we can reach higher $Q^2$ values in future to shed further light on where the perturbative QCD result emerges.

    ↳ hep-lathep-phPRD(2017)·39 citations
22. 22*

    The QCD Equation of State to $\mathcal{O}({\mu }_B^6)$ from Lattice QCD

    A. Bazavov🇺🇸 · H.-T. Ding🇨🇳 · P. Hegde🇮🇳 · O. Kaczmarek🇩🇪 · F. Karsch🇩🇪 · E. Laermann🇩🇪 · Y. Maezawa🇯🇵 · S. Mukherjee🇺🇸 · H. Ohno🇺🇸 · P. Petreczky🇺🇸 · H. Sandmeyer🇩🇪 · P. Steinbrecher🇩🇪 and 4 other authors

    We calculated the QCD equation of state using Taylor expansions that include contributions from up to sixth order in the baryon, strangeness and electric charge chemical potentials. Calculations have been performed with the Highly Improved Staggered Quark action in the temperature range $T\in [135\mathrm{MeV},330\mathrm{MeV}]$ using up to four different sets of lattice cut-offs corresponding to lattices of size $N_{\sigma }^3\times N_{\tau }$ with aspect ratio $N_{\sigma }/N_{\tau }=4$ and $N_{\tau }=6-16$. The strange quark mass is tuned to its physical value and we use two strange to light quark mass ratios $m_s/m_l=20$ and $27$, which in the continuum limit correspond to a pion mass of about $160$ MeV and $140$ MeV espectively. Sixth-order results for Taylor expansion coefficients are used to estimate truncation errors of the fourth-order expansion. We show that truncation errors are small for baryon chemical potentials less then twice the temperature (${\mu }_B\le 2T$). The fourth-order equation of state thus is suitable for the modeling of dense matter created in heavy ion collisions with center-of-mass energies down to $\sqrt{s_{NN}}\sim 12$ GeV. We provide a parametrization of basic thermodynamic quantities that can be readily used in hydrodynamic simulation codes. The results on up to sixth order expansion coefficients of bulk thermodynamics are used for the calculation of lines of constant pressure, energy and entropy densities in the $T$-${\mu }_B$ plane and are compared with the crossover line for the QCD chiral transition as well as with experimental results on freeze-out parameters in heavy ion collisions. These coefficients also provide estimates for the location of a possible critical point. We argue that results on sixth order expansion coefficients disfavor the existence of a critical point in the QCD phase diagram for ${\mu }_B/T\le 2$ and $T/T_c({\mu }_B=0)>0.9$.

    ↳ hep-lathep-phnucl-exnucl-thPRD(2017)·592 citations
23. 23*

    Casimir energy for two and three superconducting coupled cavities

    L. Rosa🇮🇹 · S. Avino🇮🇹 · E. Calloni🇮🇹 · S. Caprara🇮🇹 · M. De Laurentis🇮🇹 · R. De Rosa🇮🇹 · Giampiero Esposito🇮🇹 · M. Grilli🇮🇹 · E. Majorana🇮🇹 · G. P. Pepe🇮🇹 · S. Petrarca🇮🇹 · P. Puppo🇮🇹 and 7 other authors

    In this paper we study the behavior of the Casimir energy of a "multi-cavity" across the transition from the metallic to the superconducting phase of the constituting plates. Our analysis is carried out in the framework of the ARCHIMEDES experiment, aiming at measuring the interaction of the electromagnetic vacuum energy with a gravitational field. For this purpose it is foreseen to modulate the Casimir energy of a layered structure composing a multi-cavity coupled system by inducing a transition from the metallic to the superconducting phase. This implies a thorough study of the behavior of the cavity, where normal metallic layers are alternated with superconducting layers, across the transition. Our study finds that, because of the coupling between the cavities, mainly mediated by the transverse magnetic modes of the radiation field, the variation of energy across the transition can be very large.

    ↳ hep-thhep-phquant-phEur.Phys.J.Plus(2017)·9 citations
24. 24*

    Some radiative corrections to the hyperfine splitting of true muonium: two-photon-exchange contributions

    Yao Ji🇩🇪 · Henry Lamm🇺🇸

    We consider a set of radiative contributions from one-loop lepton vacuum polarization to the hyperfine splitting of true muonium. Improving previous results, we obtain values for the electron-loop coefficients and extract their leading dependence upon $\beta =m_{\mu }/m_e$. The coefficients are $C_{20,1\mathrm{VPCT}}^{\mu }=0.734931603\beta$, $C_{20,1\mathrm{VPCA}}^{\mu }=0.551198702\beta$, and $C_{20,1\mathrm{VPT}}^{\mu }=0.419149715\beta$. The mass-independent contribution from three one-loop vacuum polarization is $C_{40,\mathrm{VPX}}=\frac{1}{127575}\left(-5255-2016{\pi }^2+51840\zeta (3)\right)$. Contributions from $\tau$ up to $\mathcal{O}(m_{\mu }{\alpha }^8)$ are calculated.

    ↳ physics.atom-phhep-ph4 citations
25. 25*

    Quark-Nuclear Hybrid EoS with Excluded Volume Effects

    Mark Alexander Randolph Kaltenborn🇺🇸 · Niels-Uwe Friedrich Bastian🇵🇱 · David Bernhard Blaschke🇷🇺

    A two-phase description of the quark-nuclear matter hybrid equation of state that takes into account the effect of excluded volume in both the hadronic and the quark matter phases is introduced. The nuclear phase manifests a reduction of the available volume as density increases, leading to a stiffening of the matter. The quark matter phase displays a reduction of the effective string tension in the confining density functional from available volume contributions. The nuclear equation of state is based upon the relativistic density functional model DD2 with excluded volume. The quark matter is based upon a mean-field modification to the free fermi gas and will be discussed in greater detail. The interactions are decomposed into mean scalar and vector components. The scalar interaction is motivated by a string potential between quarks, whereas the vector interaction potential is motivated by higher order interactions of quarks leading to an increased stiffening at high densities. As an application, we consider matter under compact star constraints of electric neutrality and $\beta$-equilibrium. We obtain mass-radius relations for hybrid stars that form a third family, disconnected from the purely hadronic star branch, and fulfill the $2M_{\odot }$ constraint.

    ↳ astro-ph.HEhep-phnucl-thPRD(2017)·118 citations
26. 26*

    Possible Evidence for the Stochastic Acceleration of Secondary Antiprotons by Supernova Remnants

    Ilias Cholis🇺🇸 · Dan Hooper🇺🇸 · Tim Linden🇺🇸

    The antiproton-to-proton ratio in the cosmic-ray spectrum is a sensitive probe of new physics. Using recent measurements of the cosmic-ray antiproton and proton fluxes in the energy range of 1-1000 GeV, we study the contribution to the $\bar{p}/p$ ratio from secondary antiprotons that are produced and subsequently accelerated within individual supernova remnants. We consider several well-motivated models for cosmic-ray propagation in the interstellar medium and marginalize our results over the uncertainties related to the antiproton production cross section and the time-, charge-, and energy-dependent effects of solar modulation. We find that the increase in the $\bar{p}/p$ ratio observed at rigidities above $\sim$ 100 GV cannot be accounted for within the context of conventional cosmic-ray propagation models, but is consistent with scenarios in which cosmic-ray antiprotons are produced and subsequently accelerated by shocks within a given supernova remnant. In light of this, the acceleration of secondary cosmic rays in supernova remnants is predicted to substantially contribute to the cosmic-ray positron spectrum, accounting for a significant fraction of the observed positron excess.

    ↳ astro-ph.HEhep-phphysics.space-phPRD(2017)·44 citations
27. 27*

    On thermodynamic self-consistency of generic axiomatic-nonextensive statistics

    Abdel Nasser Tawfik (Egyptian Ctr. Theor. Phys., Cairo, WLCAPP, Cairo)🇪🇬 · Hayam Yassin🇪🇬 · Eman R. Abo Elyazeed (Ain Shams U., Cairo)🇪🇬

    Generic axiomatic-nonextensive statistics characterized by two asymptotic properties, to each of them a scaling function is assigned, characterized by c and d for first and second scaling property, respectively, is formulated in a grand-canonical ensemble with finite volume in the thermodynamic limit. The thermodynamic properties of a relativistic ideal gas of hadron resonances are studied. It is found that this generic statistics satisfies the requirements of the equilibrium thermodynamics. Essential aspects of thermodynamic self-consistency are clarified. Analytical expressions are proposed for the statistical fits of various transverse momentum distributions measured in most-central collisions at different collision energies and colliding systems. Estimations for the freezeout temperature and chemical potential and both c and d are determined. The earlier are found compatible with the parameters deduced from Boltzmann-Gibbs (BG) statistics (extensive), while the latter refer to generic nonextensivity. The resulting equivalence class (c,d) is associated to stretched exponentials, where Lambert function reaches its asymptotic stability. In some measurements, the resulting nonextensive entropy is linearly composed of extensive entropies. Apart from power-scaling, the particle ratios and yields are excellent quantities to highlighting whether the particle production takes place, (non)extensively. Various particle ratios and yields measured by the STAR experiment in central collisions at 200, 62.4 and 7.7 GeV are fitted to this novel approach. We found that both c and d<1, i.e. referring to neither BG- nor Tsallis-type statistics, but to (c,d)-entropy, where Lambert functions exponentially raise. We conclude that the particle production at STAR energies is likely a nonextensive process but not necessarily BG or Tsallis type.

    ↳ nucl-thhep-phCPC(2017)·9 citations
28. 28*

    High energy scattering of polarized nucleons with The phenomenological spin - orbit potential

    Nguyen Nhu Xuan

    The scattering amplitude of polarized nucleons has been found within the framework of the Klein Gordon with the phenomenological spin - orbit potential. It has the Glauber type representation. The differential cross sections of polarized nucleon are considered and discussed.The Yukawa potential is applied for this problem to determine the polarization of high energy scattering nucleons.

    ↳ nucl-thhep-ph0 citations
29. 29*

    Neutrino Fluxes from a Core-Collapse Supernova in a Model with Three Sterile Neutrinos

    A.V. Yudin🇷🇺 · D.K. Nadyozhin🇷🇺 · V.V. Khruschov🇷🇺 · S.V. Fomichev🇷🇺

    The characteristics of the gravitational collapse of a supernova and the fluxes of active and sterile neutrinos produced during the formation of its protoneutron core have been calculated numerically. The relative yields of active and sterile neutrinos in core matter with different degrees of neutronization have been calculated for various input parameters and various initial conditions. A significant increase in the fraction of sterile neutrinos produced in superdense core matter at the resonant degree of neutronization has been confirmed. The contributions of sterile neutrinos to the collapse dynamics and the total flux of neutrinos produced during collapse have been shown to be relatively small. The total luminosity of sterile neutrinos is considerably lower than the luminosity of electron neutrinos, but their spectrum is considerably harder at high energies.

    ↳ astro-ph.HEastro-ph.SRhep-phAstron.Lett.(2016)·17 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.