Thu·Jan 11, 2018Thursday·January 11, 2018

1. 01*

   $\tau \to f_1(1285){\pi }^{-}{\nu }_{\tau }$ decay in the extended Nambu -- Jona-Lasinio model

   M. K. Volkov🇷🇺 · A. A. Pivovarov🇷🇺 · A. A. Osipov🇷🇺

   Within the framework of the extended Nambu -- Jona-Lasinio model, we calculate the matrix element of the $\tau \to f_1(1285){\pi }^{-}{\nu }_{\tau }$ decay, obtain the invariant mass distribution of the $f_1\pi$ -system and estimate the branching ratio Br$(\tau \to f_1{\pi }^{-}{\nu }_{\tau })=4.0\times 10^{-4}$. The two types of contributions are considered: the contact interaction, and the axial-vector $I^G(J^{PC})=1^{-}(1^{++})$ resonance exchange. The latter includes the ground $a_1(1260)$ state, and its first radially excited state, $a_1(1640)$. The corrections caused by the $\pi -a_1$ transitions are taken into account. Our estimate is in a good agreement with the latest empirical result Br$(\tau \to f_1{\pi }^{-}{\nu }_{\tau })=(3.9\pm 0.5)\times 10^{-4}$. The distribution function obtained for the decay $\tau \to f_1(1285){\pi }^{-}{\nu }_{\tau }$ shows a clear signal of $a_1(1640)$ resonance which should be compared with future experimental data including our estimate of the decay width $\Gamma (a_1(1640)\to f_1\pi )=14.1\text{mbox}MeV$.

   hep-phEPJA(2018)·14 citations
2. 02*

   Recent progress on infrared singularities

   Einan Gardi🇬🇧

   Over the past couple of years we have had significant progress in determining long-distance singularities in gauge-theory scattering amplitudes of massless particles beyond the planar limit. Upon considering all kinematic invariants much larger than the QCD scale, the singularities factorise into universal soft and jet functions, leaving behind a finite hard-interaction amplitude. Such factorization can now be implemented in full to three loops for arbitrary scattering processes of massless partons. In particular, the soft anomalous dimension for a general configuration of $n$ coloured particles was computed to this order, where it displays for the first time non-dipole interactions that correlate the colour and kinematic degrees of freedom of three and four particles. In parallel, there has been progress in understanding amplitudes and their singularities in special kinematic limits, such as collinear limits of multi-leg amplitudes and the high-energy limit in $2\to 2$ scattering. These relate respectively to different factorization properties of gauge-theory amplitudes. In this talk I describe the state of the art and illustrate the interplay between the analysis of the singularities for general kinematics and the properties of amplitudes in special kinematic limits.

   hep-phhep-thPoS(2018)·2 citations
3. 03*

   Chiral criticality and glue dynamics

   Wei-jie Fu🇨🇳

   The chiral order-parameter $\sigma$ field and its higher-order cumulants of fluctuations are calculated within the functional renormalization group approach. The influence of the glue dynamics on the fluctuations of $\sigma$ field is investigated, and we find that the $\sigma$-field fluctuations are weakly affected by the glue dynamics. This is in sharp contrast to the baryon number fluctuations, which are sensitive to the glue dynamics and involve information of the color confinement. Implications of our calculated results on theoretical and experimental efforts to search for the QCD critical ending point are discussed.

   hep-phCPC(2019)·7 citations
4. 04*

   The Energy-Energy Correlation at Next-to-Leading Order in QCD, Analytically

   Lance J. Dixon🇺🇸 · Ming-xing Luo🇨🇳 · Vladyslav Shtabovenko🇨🇳 · Tong-Zhi Yang🇨🇳 · Hua Xing Zhu🇨🇳

   The energy-energy correlation (EEC) between two detectors in $e^{+}{e}^{-}$ annihilation was computed analytically at leading order in QCD almost 40 years ago, and numerically at next-to-leading order (NLO) starting in the 1980s. We present the first analytical result for the EEC at NLO, which is remarkably simple, and facilitates analytical study of the perturbative structure of the EEC. We provide the expansion of EEC in the collinear and back-to-back regions through to next-to-leading power, information which should aid resummation in these regions.

   hep-phPRL(2018)·141 citations
5. 05*

   Multifractal Characteristics of Multiparticle Production in Heavy-Ion Collisions at SPS Energies

   Shaista Khan🇮🇳 · Shakeel Ahmad🇮🇳

   Entropy, dimensions and other multifractal characteristics of multiplicity distributions of relativistic charged hadrons produced in ion-ion collisions at SPS energies are investigated. The analysis of the experimental data is carried out in terms of phase space bin-size dependence of multiplicity distributions following the Takagi's approach. Yet another method is also followed to study the multifractality which, is not related to the bin-width and (or) the detector resolution, rather involves multiplicity distribution of charged particles in full phase space in terms of information entropy and its generalization, Rényi's order-q information entropy. The findings reveal the presence of multifractal structure-- a remarkable property of the fluctuations. Nearly constant values of multifractal specific heat, 'c' estimated by the two different methods of analysis followed indicate that the parameter 'c' may be used as a universal characteristic of the particle production in high energy collisions. The results obtained from the analysis of the experimental data agree well with the predictions of Monte Carlo model AMPT.

   hep-phnucl-thIJMPE(2018)·8 citations
6. 06*

   Anti-triplet charmed baryon decays with SU(3) Flavor Symmetry

   C.Q. Geng🇨🇳 · Y.K. Hsiao🇨🇳 · Chia-Wei Liu🇹🇼 · Tien-Hsueh Tsai🇹🇼

   We study the decays of the anti-triplet charmed baryon state $({\Xi }_c^0,{\Xi }_c^{+},{\Lambda }_c^{+})$ based on the $SU(3)$ flavor symmetry. In particular, after predicting $\mathcal{B}({\Xi }_c^0\to {\Xi }^{-}{\pi }^{+})=(15.7\pm 0.7)\times 10^{-3}$ and $\mathcal{B}({\Xi }_c^{+}\to {\Xi }^{-}{\pi }^{+}{\pi }^{+})=(14.7\pm 8.4)\times 10^{-3}$, we extract that $\mathcal{B}({\Xi }_c^0\to \Lambda K^{-}{\pi }^{+},\Lambda K^{+}{K}^{-},{\Xi }^{-}{e}^{+}{\nu }_e)=(16.8\pm 2.3,0.45\pm 0.11,48.7\pm 17.4)\times 10^{-3}$ and $\mathcal{B}({\Xi }_c^{+}\to p{K}_s^0{K}_s^0,{\Sigma }^{+}{K}^{-}{\pi }^{+},{\Xi }^0{\pi }^{+}{\pi }^0,{\Xi }^0{e}^{+}{\nu }_e)=(1.3\pm 0.8,13.8\pm 8.0,33.8\pm 21.9,33.8_{-22.6}^{+21.9})\times 10^{-3}$. We also find that $\mathcal{B}({\Xi }_c^0\to {\Xi }^0\eta ,{\Xi }^0{\eta }^{\prime })=(1.7_{-1.7}^{+1.0},8.6_{-6.3}^{+11.0})\times 10^{-3}$, $\mathcal{B}({\Xi }_c^0\to {\Lambda }^0\eta ,{\Lambda }^0{\eta }^{\prime })=(1.6_{-0.8}^{+1.2},9.4_{-6.8}^{+11.6})\times 10^{-4}$ and $\mathcal{B}({\Xi }_c^{+}\to {\Sigma }^{+}\eta ,{\Sigma }^{+}{\eta }^{\prime })=(28.4_{-6.9}^{+8.2},13.2_{-11.9}^{+24.0})\times 10^{-4}$. These ${\Xi }_c$ decays with the branching ratios of $O(10^{-4}-10^{-3})$ are clearly promising to be observed by the BESIII and LHCb experiments.

   hep-phhep-exPRD(2018)·102 citations
7. 07*

   Recent IR-Improved results for LHC/FCC physics

   B.F.L. Ward (1)🇺🇸 · Aditi Mukhopadhyay (2)🇺🇸 · Bahram Shakerin (1)🇺🇸 · Zbigniew A. Was (3)🇵🇱 · Scott A. Yost (4) ((1) Baylor University, Waco, TX, USA, (2) AstraZeneca, Chennai, India, (3) Institute of Nuclear Physics, Krakow, Poland, (4) The Citadel, Charleston, SC, USA)🇺🇸

   We present recent developments in the theory and application of IR-improved QED$\otimes$QCD resummation methods, realized by MC event generator methods, for LHC and FCC physics scenarios.

   hep-phPoS(2018)·2 citations
8. 08*

   $b\to c\ell \nu$ anomalies in light of extended scalar sectors

   Aritra Biswas🇮🇳 · Dilip Kumar Ghosh🇮🇳 · Sunando Kumar Patra🇮🇳 · Avirup Shaw🇮🇳

   Considering the recent experimental results on exclusive semileptonic $B$ meson decays showing sizable departure from their Standard Model prediction of lepton flavor universality and keeping ongoing and proposed non-standard Higgs searches in mind, we explore the charged current flavor observables (${\mathcal{R}}_{D^{(\ast )}}$, ${\mathcal{R}}_{J/\psi }$), among other $b\to c\ell \nu$ transitions, in the presence of a relevant scalar current effective new physics operator. We use $B_c$ lifetime and predicted bounds on the branching fraction of $B_c\to \tau \nu$ decay as constraints. We show the allowed parameter space in terms of the real and imaginary parts of the corresponding Wilson coefficients for such interactions. Under the light of obtained results, we study the prospect of two benchmark models, rendering the Wilson coefficients real (Georgi-Machacek (GM)) and complex (Leptoquark (LQ)) respectively. We show that constraints from $b\to c\ell \nu$ on GM parameters are consistent with other flavor constraints on the model, if we drop the \Babar~results. Including those disfavors the model by more than $3\sigma$. On the other hand, one benchmark LQ scenario, which gives rise to a single scalar current effective interaction, is still allowed within $68\%$ confidence level, albeit with a shrunk parameter space.

   hep-phhep-exInt.J.Mod.Phys.A(2019)·41 citations
9. 09*

   Leptoquarks in Flavour Physics

   Dario Müller🇨🇭

   While the LHC has not directly observed any new particle so far, experimental results from LHCb, BELLE and BABAR point towards the violation of lepton flavour universality in $b\to s{\ell }^{+}{\ell }^{-}$ and $b\to c\ell \nu$. In this context, also the discrepancy in the anomalous magnetic moment of the muon can be interpreted as a sign of lepton flavour universality violation. Here we discuss how these hints for new physics can also be explained by introducing leptoquarks as an extension of the Standard Model. Indeed, leptoquarks are good candidates to explain the anomaly in the anomalous magnetic moment of the muon because of an $m_t/m_{\mu }$ enhanced contribution giving correlated effects in $Z$ boson decays which is particularly interesting in the light of future precision experiments.

   hep-phEPJ Web Conf.(2018)·12 citations
10. 10*

    $b$ quark mass effects in associated production

    Davide Napoletano🇬🇧

    In this work we study an extension of the commonly used 5F scheme, where $b$ quarks are treated as massless partons, in which full mass effects are retained in both the initial and in the final state. We name this scheme 5F massive scheme (5FMS). We implement this scheme in the \Sherpa Monte Carlo event generator at MEPS@NLO accuracy, and we compare it for two relevant cases for the LHC: $b\bar{b}\to H$ and $pp\to Zb$.

    hep-phhep-exActa Phys.Polon.Supp.(2018)·0 citations
11. 11*

    Tachyon constant-roll inflation

    A. Mohammadi🇮🇷 · Kh. Saaidi🇮🇷 · T. Golanbari🇮🇷

    The constant-roll inflation is studied where the inflaton is taken as a tachyon field. Since in this approach the second slow-roll parameter is assumed to be of order one instead of being small, then the perturbation parameters will be considered again. The results are compared with observational data, and it is confirmed that the model could stand as a proper candidate for inflation.

    hep-phPRD(2018)·46 citations
12. 12*

    $B+L$ violation at colliders and new physics

    David G. Cerdeno🇬🇧 · Peter Reimitz🇩🇪 · Kazuki Sakurai🇵🇱 · Carlos Tamarit🇩🇪

    Chiral electroweak anomalies predict fermion interactions that violate baryon ($B$) and lepton number ($L$), and can be dressed with large numbers of Higgs and gauge bosons. The estimation of the total $B+L$ violating rate from an initial two-particle state --potentially observable at colliders-- has been the subject of an intense discussion, mainly centered on the resummation of boson emission, which is believed to contribute to the cross-section with an exponential function of the energy, yet with an exponent (the "holy-grail" function) which is not fully known in the energy range of interest. In this article we focus instead on the effect of fermions beyond the Standard-Model (SM) in the polynomial contributions to the rate. It is shown that $B+L$ processes involving the new fermions have a polynomial contribution that can be several orders of magnitude greater than in the SM, for high centre-of-mass energies and light enough masses. We also present calculations that hint at a simple dependence of the holy grail function on the heavy fermion masses. Thus, if anomalous $B+L$ violating interactions are ever detected at high-energy colliders, they could be associated with new physics.

    hep-phhep-thJHEP(2018)·16 citations
13. 13*

    Prediction of new states from $D^{(\ast )}{B}^{(\ast )}{\bar{B}}^{(\ast )}$ three-body interactions

    J. M. Dias🇪🇸 · L. Roca🇪🇸 · S. Sakai🇪🇸

    We study three-body systems composed of $D^{(\ast )}$, $B^{(\ast )}$ and ${\bar{B}}^{(\ast )}$ in order to look for possible bound states or resonances. In order to solve the three-body problem, we use the fixed center approach for the Faddeev equations considering that the $B^{\ast }{\bar{B}}^{\ast }(B\bar{B})$ are clusterized systems, generated dynamically, which interact with a third particle $D(D^{\ast })$ whose mass is much smaller than the two-body bound states forming the cluster. In the $D{B}^{\ast }{\bar{B}}^{\ast }$, $D^{\ast }{B}^{\ast }{\bar{B}}^{\ast }$, $DB\bar{B}$ and $D^{\ast }B\bar{B}$ systems with $I=1/2$, we found clear bound state peaks with binding energies typically a few tens MeV and more uncertain broad resonant states about ten MeV above the threshold with widths of a few tens MeV.

    hep-phPRD(2018)·12 citations
14. 14*

    Top-philic $Z^{\prime }$ Forces at the LHC

    Patrick J. Fox🇺🇸 · Ian Low🇺🇸 · Yue Zhang🇺🇸

    Despite extensive searches for an additional neutral massive gauge boson at the LHC, a $Z^{\prime }$ at the weak scale could still be present if its couplings to the first two generations of quarks are suppressed, in which case the production in hadron colliders relies on tree-level processes in association with heavy flavors or one-loop processes in association with a jet. We consider the low-energy effective theory of a top-philic $Z^{\prime }$ and present possible UV completions. We clarify theoretical subtleties in evaluating the production of a top-philic $Z^{\prime }$ at the LHC and examine carefully the treatment of an anomalous $Z^{\prime }$ current in the low-energy effective theory. Recipes for properly computing the production rate in the $Z^{\prime }+j$ channel are given. We discuss constraints from colliders and low-energy probes of new physics. As an application, we apply these considerations to models that use a weak-scale $Z^{\prime }$ to explain possible violations of lepton universality in $B$ meson decays, and show that the future running of a high luminosity LHC can potentially cover much of the remaining parameter space favored by this particular interpretation of the $B$ physics anomaly.

    hep-phhep-exJHEP(2018)·53 citations
15. 15*

    micrOMEGAs5.0 : freeze-in

    Geneviève Bélanger🇫🇷 · Fawzi Boudjema🇫🇷 · Andreas Goudelis🇫🇷 · Alexander Pukhov🇷🇺 · Bryan Zaldivar🇫🇷

    We present a major upgrade of the micrOMEGAs dark matter code to compute the abundance of feebly interacting dark matter candidates through the freeze-in mechanism in generic extensions of the Standard Model of particle physics. We develop the necessary formalism in order to solve the freeze-in Boltzmann equations while making as few simplifying assumptions as possible concerning the phase-space distributions of the particles involved in the dark matter production process. We further show that this formalism allows us to treat different freeze-in scenarios and discuss the way it is implemented in the code. We find that, depending on the New Physics scenario under consideration, the effect of a proper treatment of statistics on the predicted dark matter abundance can range from a few percent up to a factor of two, or more. We moreover illustrate the underlying physics, as well as the various novel functionalities of micrOMEGAs, by presenting several example results obtained for different dark matter models.

    hep-phComput.Phys.Commun.(2018)·593 citations
16. 16*

    QCD thermodynamics from lattice calculations with non-equilibrium methods: The SU(3) equation of state

    Michele Caselle🇮🇹 · Alessandro Nada🇮🇹 · Marco Panero🇮🇹

    A precise lattice determination of the equation of state in SU(3) Yang-Mills theory is carried out by means of a simulation algorithm, based on Jarzynski's theorem, that allows one to compute physical quantities in thermodynamic equilibrium, by driving the field configurations of the system out of equilibrium. The physical results and the computational efficiency of the algorithm are compared with other state-of-the-art lattice calculations, and the extension to full QCD with dynamical fermions and to other observables is discussed.

    ↳ hep-lathep-phhep-thnucl-thPRD(2018)·62 citations
17. 17*

    Primordial Black Holes from Inflaton Fragmentation into Oscillons

    Eric Cotner🇺🇸 · Alexander Kusenko🇺🇸 · Volodymyr Takhistov🇺🇸

    We show that fragmentation of the inflaton into long-lived spatially localized oscillon configurations can lead to copious production of black holes. In a single-field inflation model primordial black holes of sublunar mass can form, and they can account for all of the dark matter. We also explore the possibility that solar-mass primordial black holes, particularly relevant for gravitational wave astronomy, are produced from the same mechanism.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2018)·175 citations
18. 18*

    Applications of deep learning to relativistic hydrodynamics

    Hengfeng Huang🇨🇳 · Bowen Xiao🇨🇳 · Ziming Liu🇨🇳 · Zeming Wu🇨🇳 · Yadong Mu🇨🇳 · Huichao Song🇨🇳

    Relativistic hydrodynamics is a powerful tool to simulate the evolution of the quark gluon plasma (QGP) in relativistic heavy ion collisions. Using 10000 initial and final profiles generated from 2+1-d relativistic hydrodynamics VISH2+1 with MC-Glauber initial conditions, we train a deep neural network based on stacked U-net, and use it to predict the final profiles associated with various initial conditions, including MC-Glauber, MC-KLN and AMPT and TRENTo. A comparison with the VISH2+1 results shows that the network predictions can nicely capture the magnitude and inhomogeneous structures of the final profiles, and nicely describe the related eccentricity distributions $P({\epsilon }_n)$ (n=2, 3, 4). These results indicate that deep learning technique can capture the main features of the non-linear evolution of hydrodynamics, showing its potential to largely accelerate the event-by-event simulations of relativistic hydrodynamics.

    ↳ nucl-thastro-ph.HEcond-mat.dis-nnhep-phPRResearch(2021)·32 citations
19. 19*

    Some Remarks on Anthropic Approaches to the Strong CP Problem

    Michael Dine🇺🇸 · Laurel Stephenson Haskins🇮🇱 · Lorenzo Ubaldi🇮🇹 · Di Xu🇺🇸

    The peculiar value of $\theta$ is a challenge to the notion of an anthropic landscape. We briefly review the possibility that a suitable axion might arise from an anthropic requirement of dark matter. We then consider an alternative suggestion of Kaloper and Terning that $\theta$ might be correlated with the cosmological constant. We note that in a landscape one expects that $\theta$ is determined by the expectation value of one or more axions. We discuss how a discretuum of values of $\theta$ might arise with an energy distribution dominated by QCD, and find the requirements to be quite stringent. Given such a discretuum, we find limited circumstances where small $\theta$ might be selected by anthropic requirements on the cosmological constant.

    ↳ hep-thhep-phJHEP(2018)·32 citations
20. 20*

    Small System Collectivity in Relativistic Hadron and Nuclear Collisions

    J.L. Nagle🇺🇸 · W.A. Zajc🇺🇸

    The bulk motion of nuclear matter at the ultra-high temperatures created in heavy-ion collisions at the Relativistic Heavy Ion Collider and the Large Hadron Collider is well described in terms of nearly inviscid hydrodynamics, thereby establishing this system of quarks and gluons as the most perfect fluid in nature. A revolution in the field is underway, spearheaded by the discovery of similar collective, fluid-like phenomena in much smaller systems including p+p, p+A, d+Au, and ${}^3$He$+$Au collisions. We review these exciting new observations and their implications.

    ↳ nucl-exhep-phnucl-thAnn.Rev.Nucl.Part.Sci.(2018)·472 citations
21. 21*

    TASI Lectures on Remnants from the String Landscape

    James Halverson🇺🇸 · Paul Langacker🇺🇸

    Superstring theories are very promising theoretically, but the enormous landscape of string vacua and the (likely) very large underlying string scale imply that they may never be tested directly. Nevertheless, concrete constructions consistent with the observed world frequently lead to observable remnants, i.e., new particles or features that are apparently accidental consequences of the ultraviolet theory and that are typically not motivated by specific shortcomings of the standard models of particle physics or cosmology. For example, moduli, axions, large extended gauge sectors, additional $Z^{\prime }$ gauge bosons, extended Higgs/Higgsino sectors, and quasi-chiral exotics are extremely common. They motivate alternative cosmological paradigms and could lead to observable signatures at the LHC. Similar features can emerge in other standard model extensions, but in the stringy case they are more likely to occur in isolation and not as part of a more complete TeV-scale structure. Conversely, some common aspects of the infinite "landscape" of field theories, such as large representations, are expected to be very rare in the string landscape, and observation of features definitively in the swampland could lead to falsification. In this article, common stringy remnants and their phenomenology are surveyed, and implications for indirectly supporting or casting doubt on string theory are discussed.

    ↳ hep-thhep-exhep-phPoS(2018)·52 citations
22. 22*

    Impenetrable barriers for positrons in neighbourhood of superheavy nuclei with $Z>118$

    V.P.Neznamov

    Analysis of quantum mechanical motion of charged half-spin particles in the repulsive Coulomb field by means of second-order equation results in that an impenetrable potential barrier not explored earlier was found. For a particle at rest with a reduced mass $m$, the barrier radius is equal to half classical radius: the barrier radius decreases with increase in the particle energy. For the stable and quasi-stable nuclei with $Z>118$, presence of an impenetrable barrier as ${\beta }^{+}$-decay leads to the existence of "traps" for positrons in the neighbourhood of nuclei and as $Z_{cr}\simeq 170$ (with emission of electron-positron pairs by vacuum) leads to the existence of a quasi-constant source of annihilation quanta.

    ↳ physics.gen-phhep-phJ.Phys.Conf.Ser.(2017)·0 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.