Wed·Dec 2, 2015Wednesday·December 2, 2015

1. 01*

   Production of t$\gamma$, tZ and tH via Flavour Changing Neutral Currents

   Artur Amorim🇵🇹 · Juan Pedro Araque🇵🇹 · Nuno Filipe Castro🇵🇹 · Jose Santiago🇪🇸 · Rui Santos🇵🇹

   A UFO model describing general top quark Flavour Changing Neutral Currents is presented. We use it to study t$\gamma$, tH and tZ production via FCNCs anomalous couplings at the Large Hadron Collider, in particular how the distributions of physical observables depend on the anomalous couplings. A sensitivity study of the Large Hadron Collider experiments to tZ production via FCNC in its second stage of operation is also performed.

   hep-phhep-exPoS(2016)·2 citations
2. 02*

   Probing top-antitop resonances with $t\bar{t}$ scattering at LHC14

   Da Liu🇨🇳 · Rakhi Mahbubani🇨🇭

   We explore the sensitivity of the LHC at 14 TeV centre-of-mass energy (LHC14) to the single production and decay of top-antitop resonances in the four-top final state. We focus on the same-sign dilepton channel, and work within a simplified model with a vector boson coupling to the Standard Model only via its interactions with right-handed top quarks. We find it is possible to discover (exclude) such a vector boson with 300 fb${}^{-1}$ of integrated luminosity up to a mass of 1.2 (1.6) TeV for a modest coupling to tops of $g_{\rho }$=2. We present our results as an exclusion limit on the cross-section$\times$branching ratio for ease of recasting, and interpret them in the context of the gauge-singlet vector boson ${\rho }_X$ present in many simple Composite Higgs theories.

   hep-phJHEP(2016)·14 citations
3. 03*

   Perturbative thermodynamics at nonzero isospin density for cold QCD

   Thorben Graf🇩🇪 · Juergen Schaffner-Bielich🇩🇪 · Eduardo S. Fraga🇧🇷

   We use next-to-leading-order in perturbation theory to investigate the effects of a finite isospin density on the thermodynamics of cold strongly interacting matter. Our results include nonzero quark masses and are compared to lattice data.

   hep-phPRD(2016)·18 citations
4. 04*

   The QUAX proposal: a search of galactic axion with magnetic materials

   Giuseppe Ruoso🇮🇹 · Augusto Lombardi🇮🇹 · Antonello Ortolan🇮🇹 · Ruggero Pengo🇮🇹 · Caterina Braggio🇮🇹 · Giovanni Carugno🇮🇹 · Carmelo Sebastiano Gallo🇮🇹 · Clive C. Speake🇬🇧

   Aim of the QUAX (QUaerere AXion) proposal is to exploit the interaction of cosmological axions with the spin of electrons in a magnetized sample. Their effect is equivalent to the application of an oscillating rf field with frequency and amplitude which are fixed by axion mass and coupling constant, respectively. The rf receiver module of the QUAX detector consists of magnetized samples with the Larmor resonance frequency tuned to the axion mass by a polarizing static magnetic field. The interaction of electrons with the axion-equivalent rf field produces oscillations in the total magnetization of the samples. To amplify such a tiny field, a pump field at the same frequency is applied in a direction orthogonal to the polarizing field. The induced oscillatory magnetization along the polarizing field is measured by a SQUID amplifier operated at its quantum noise level.

   hep-phphysics.ins-detJ.Phys.Conf.Ser.(2016)·35 citations
5. 05*

   CP Violation in the $B_s^0$ system

   Marina Artuso🇺🇸 · Guennadi Borissov🇬🇧 · Alexander Lenz🇬🇧

   We review experimental and theoretical aspects of CP violation in the $B_s^0$-system. In that respect we present updates for the mixing parameters of the $B_s^0$ mesons expected in the Standard Model (SM): the mass difference $\Delta M_s^{\mathrm{SM}}=(18.3\pm 2.7)$ ps${}^{-1}$, the decay rate difference $\Delta {\Gamma }_s^{\mathrm{SM}}=(0.085\pm 0.015)$ ps${}^{-1}$, the flavour specific CP asymmetry $a_{\mathrm{fs}}^{s,\mathrm{SM}}=(2.22\pm 0.27)\cdot 10^{-5}$ and the equivalent quantities in the $B^0$-sector. The experimental measurements of $\Delta M_s$ and $\Delta {\Gamma }_s$ are more precise and agree very well with theoretica predictions, which can also be viewed as a proof of theoretical tools, like the Heavy Quark Expansion (HQE). CP violating studies in the $B_s^0$ system provide essential information to test the SM expectations. Mixing quantities can be used to study model independent bounds on new physics (NP) effects, yielding the familiar picture: the standard model (SM) gives the dominant contribution, while there is still some sizable space for NP effects. In the case of $\Delta M_s$ effects of the order of $15\%$ are not excluded. In the CP phase ${\varphi }_s$ due to CP violation in the interference of decays and mixing $\mathcal{O}(100\%)$ effects are still possible. The semi-leptonic CP asymmetry $a_{\mathrm{sl}}^s$, which is due to CP violation in mixing, could still be a factor of 250 larger than its robust SM expectation and thus provides a very clean observable for NP searches. We comment in detail on theoretical improvements that are necessary to make full use of the experimental precision.

   hep-phhep-exRMP(2016)·207 citations
6. 06*

   Initial-state splitting kernels in cold nuclear matter

   Grigory Ovanesyan🇺🇸 · Felix Ringer🇺🇸 · Ivan Vitev🇺🇸

   We derive medium-induced splitting kernels for energetic partons that undergo interactions in dense QCD matter before a hard-scattering event at large momentum transfer $Q^2$. Working in the framework of the effective theory ${\mathrm{SCET}}_{\mathrm{G}}$, we compute the splitting kernels beyond the soft gluon approximation. We present numerical studies that compare our new results with previous findings. We expect the full medium-induced splitting kernels to be most relevant for the extension of initial-state cold nuclear matter energy loss phenomenology in both p+A and A+A collisions.

   hep-phnucl-thPLB(2016)·14 citations
7. 07*

   Next-to-next-to-leading logarithmic resummation for transverse thrust

   Thomas Becher🇨🇭 · Xavier Garcia i Tormo🇨🇭 · Jan Piclum🇨🇭

   We obtain a prediction for the hadron-collider event-shape variable transverse thrust in which the terms enhanced in the dijet limit are resummed to next-to-next-to-leading logarithmic accuracy. Our method exploits universality properties made manifest in the factorized expression for the cross section and only requires one-loop calculations. The necessary two-loop ingredients are extracted using known results and existing numerical codes. Our technique is general and applicable to other observables as well.

   hep-phPRD(2016)·28 citations
8. 08*

   Sequestered gravity in gauge mediation

   Ignatios Antoniadis🇫🇷 · Karim Benakli🇫🇷 · Mariano Quiros🇪🇸

   We present a novel mechanism of supersymmetry breaking embeddable in string theory and simultaneously sharing the main advantages of (sequestered) gravity and gauge mediation. It is driven by a Scherk-Schwarz deformation along a compact extra dimension, transverse to a D-brane stack supporting the supersymmetric extension of the Standard Model. This fixes the magnitude of the gravitino mass, together with that of the gauginos of a bulk gauge group, at a scale as high as $10^{10}$ GeV. Supersymmetry breaking is mediated to the observable sector dominantly by gauge interactions using massive messengers transforming non-trivially under the bulk and Standard Model gauge groups and leading to a neutralino LSP as dark matter candidate. The Higgsino mass $\mu$ and soft Higgs-bilinear B$\mu$-term could be generated at the same order of magnitude as the other soft terms by effective supergravity couplings as in the Giudice-Masiero mechanism.

   hep-phEPJC(2016)·8 citations
9. 09*

   Scalar Leptons in Folded Supersymmetry

   Gustavo Burdman🇧🇷 · Raffaele Tito D'Agnolo🇺🇸

   Folded supersymmetry is a natural theory of the electroweak scale in which the scalar top partner responsible for canceling the ultraviolet sensitivity of the Higgs mass at one loop carries no color. As a result, bounds on naturalness on these theories are more relaxed than in typical supersymmetric models, since collider bounds on top partners are less stringent. Here we consider the lepton sector of these theories. We show that a natural realization in a five-dimensional completion requires the existence of scalar leptons with weak scale masses and study their phenomenology. We derive bounds on the masses of these sleptons from the LHC data at $\sqrt{s}=8$TeV and study the sensitivity of the $\sqrt{s}=13$TeV run for various integrated luminosities. When supersymmetry is broken exclusively by Scherk-Schwarz boundary conditions the sleptons are stable on collider scales. This leads to bounds on the folded sleptons that translate into masses above $1$TeV for the folded stops resulting in tuning. When additional sources of supersymmetry breaking, which may be necessary to ensure electroweak symmetry breaking, are allowed the bounds on stops are mostly avoided. On the other hand, these terms lead to faster slepton decays resulting in interesting signals with highly displaced vertices and multi-jet final states inside the detectors.

   hep-phhep-ex6 citations
10. 10*

    Probing the Electroweak Phase Transition at the LHC

    Peisi Huang🇺🇸 · Aniket Joglekar🇺🇸 · Bing Li🇺🇸 · Carlos E.M. Wagner🇺🇸

    We study the correlation between the value of the triple Higgs coupling and the nature of the electroweak phase transition. We use an effective potential approach, including higher order, non-renormalizable terms coming from integrating out new physics. We show that if only the dimension six operators are considered, large positive deviations of the triple Higgs coupling from its Standard Model (SM) value are predicted in the regions of parameter space consistent with a strong first order electroweak phase transition (SFOEPT). We also show that at higher orders sizable and negative deviations of the triple Higgs coupling may be obtained, and the sign of the corrections tends to be correlated with the order of the phase transition. We also consider a singlet extension of the SM, which allows us to establish the connection with the effective field theory (EFT) approach and analyze the limits of its validity. Furthermore, we study how to probe the triple Higgs coupling from the double Higgs production at the LHC. We show that selective cuts in the invariant mass of the two Higgs bosons should be used, to maximize the sensitivity for values of the triple Higgs coupling significantly different from the Standard Model one.

    hep-phhep-exPRD(2016)·79 citations
11. 11*

    Aspects of QCD Current Algebra on a Null Plane

    Silas R. Beane🇺🇸 · Timothy J. Hobbs🇺🇸

    Consequences of QCD current algebra formulated on a light-like hyperplane are derived for the forward scattering of vector and axial-vector currents on an arbitrary hadronic target. It is shown that current algebra gives rise to a special class of sum rules that are direct consequences of the independent chiral symmetry that exists at every point on the two-dimensional transverse plane orthogonal to the lightlike direction. These sum rules are obtained by exploiting the closed, infinite-dimensional algebra satisfied by the transverse moments of null-plane axial-vector and vector charge distributions. In the special case of a nucleon target, this procedure leads to the Adler-Weisberger, Gerasimov-Drell-Hearn, Cabbibo-Radicatti and Fubini-Furlan-Rossetti sum rules. Matching to the dispersion-theoretic language which is usually invoked in deriving these sum rules, the moment sum rules are shown to be equivalent to algebraic constraints on forward S-matrix elements in the Regge limit.

    hep-phnucl-thAnnals Phys.(2016)·5 citations
12. 12*

    Dense Axion Stars

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

    If the dark matter particles are axions, gravity can cause them to coalesce into axion stars, which are stable gravitationally bound systems of axions. In the previously known solutions for axion stars, gravity and the attractive force between pairs of axions are balanced by the kinetic pressure. The mass of these dilute axion stars cannot exceed a critical mass, which is about $10^{-14}{M}_{\odot }$ if the axion mass is $10^{-4}$~eV. We study axion stars using a simple approximation to the effective potential of the nonrelativistic effective field theory for axions. We find a new branch of dense axion stars in which gravity is balanced by the mean-field pressure of the axion Bose-Einstein condensate. The mass on this branch ranges from about $10^{-20}{M}_{\odot }$ to about $M_{\odot }$. If a dilute axion star with the critical mass accretes additional axions and collapses, it could produce a bosenova, leaving a dense axion star as the remnant.

    hep-phastro-ph.COPRL(2016)·171 citations
13. 13*

    Effective Theory of Higgs Sector Vacuum States

    Daniel Egana-Ugrinovic🇺🇸 · Scott Thomas🇺🇸

    The effective field theory description for modifications of Standard Model-like Higgs boson interactions arising from tree-level mixing with heavy Higgs sector vacuum states without conserved quantum numbers is presented. An expansion in terms of effective operator dimension based on powers of the heavy mass scale rather than operator dimension is utilized to systematically organize interactions within the effective theory. Vacuum states arising from electroweak singlet extensions of the Higgs sector yield at leading order only two effective dimension-six operators. One of these uniformly dilutes all the interactions of a single physical Higgs boson as compared with Standard Model expectations, while the combination of the two operators give more general modifications of all remaining interactions with two or more physical Higgs bosons. Vacuum states arising from an additional electroweak doublet yield three types of effective dimension-six operators that modify physical Higgs boson couplings to fermion pairs, self-couplings, and introduce four-fermion interactions. However, in this case modification of physical Higgs boson interactions with massive gauge bosons arise at leading order only from three effective dimension-eight operators. If the underlying Yukawa couplings of the additional electroweak doublet satisfy the Glashow-Weinberg condition then time reversal violation at effective dimension-six depends on a single universal phase appearing only in couplings of physical Higgs bosons to fermion pairs. In all cases the couplings of any three physical states in the effective theory description must be equal to those in a unitary mixing description in order for the long distance non-analytic components of physical on-shell scattering amplitudes to agree, while in contrast couplings of four or more physical states in general differ due to short distance effects.

    hep-ph30 citations
14. 14*

    Parametric Instability of Classical Yang-Mills Fields in an Expanding Geometry

    Shoichiro Tsutsui🇯🇵 · Teiji Kunihiro🇯🇵 · Akira Ohnishi🇯🇵

    We investigate the instability of classical Yang-Mills field in an expanding geometry under a color magnetic background field within the linear regime. We consider homogeneous, boost-invariant and time-dependent color magnetic fields simulating the glasma configuration. We introduce the conformal coordinates which enable us to map an expanding problem approximately into a nonexpanding problem. We find that the fluctuations with finite longitudinal momenta can grow exponentially due to parametric instability. Fluctuations with finite transverse momenta can also show parametric instability, but their momenta are restricted to be small. The most unstable modes start to grow exponentially in the early stage of the dynamics and they may affect the thermalization in heavy-ion collisions.

    hep-phnucl-thPRD(2016)·5 citations
15. 15*

    The Diboson Excesses in an Anomaly Free Leptophobic Left-Right Model

    Kasinath Das🇮🇳 · Tianjun Li🇨🇳 · S. Nandi🇺🇸 · Santosh Kumar Rai🇮🇳

    The resonant excesses around 2 TeV reported by the ATLAS Collaboration can be explained in the left-right model, and the tight constraints from lepton plus missing energy searches can be evaded if the $SU(2{)}_R$ gauge symmetry is leptophobic. We for the first time propose an anomaly free leptophobic left-right model with gauge symmetry $SU(3{)}_C\times SU(2{)}_L\times SU(2{)}_R\times U(1{)}_X$ where the SM leptons are singlets under $SU(2{)}_R$. The gauge anomalies are cancelled by introducing extra vector-like quarks. The mass of $Z^{\prime }$ gauge boson, which cannot be leptophobic, is assumed to be around or above 2.5 TeV so that the constraint on dilepton final state can be avoided. Moreover, we find that the $W^{\prime }\to WZ$ channel cannot explain the ATLAS diboson excess due to the tension with the constraint on $W^{\prime }\to jj$ decay mode. We solve this problem by considering the mixings between the SM quarks and vector-like quarks. We show explicitly that the ATLAS diboson excess can be explained in the viable parameter space of our model, which is consistent with all the current experimental constraints.

    hep-phhep-exPRD(2016)·18 citations
16. 16*

    Production of electroweak bosons at hadron colliders: theoretical aspects

    Michelangelo L. Mangano🇨🇭

    Since the W and Z discovery, hadron colliders have provided a fertile ground, in which continuously improving measurements and theoretical predictions allow to precisely determine the gauge boson properties, and to probe the dynamics of electroweak and strong interactions. This article will review, from a theoretical perspective, the role played by the study, at hadron colliders, of electroweak boson production properties, from the better understanding of the proton structure, to the discovery and studies of the top quark and of the Higgs, to the searches for new phenomena beyond the Standard Model.

    hep-phAdv.Ser.Direct.High Energy Phys.(2016)·15 citations
17. 17*

    G2HDM : Gauged Two Higgs Doublet Model

    Wei-Chih Huang🇬🇧 · Yue-Lin Sming Tsai🇯🇵 · Tzu-Chiang Yuan🇹🇼

    A novel model embedding the two Higgs doublets in the popular two Higgs doublet models into a doublet of a non-abelian gauge group $SU(2{)}_H$ is presented. The Standard Model $SU(2{)}_L$ right-handed fermion singlets are paired up with new heavy fermions to form $SU(2{)}_H$ doublets, while $SU(2{)}_L$ left-handed fermion doublets are singlets under $SU(2{)}_H$. Distinctive features of this anomaly-free model are: (1) Electroweak symmetry breaking is induced from spontaneous symmetry breaking of $SU(2{)}_H$ via its triplet vacuum expectation value; (2) One of the Higgs doublet can be inert, with its neutral component being a dark matter candidate as protected by the $SU(2{)}_H$ gauge symmetry instead of a discrete $Z_2$ symmetry in the usual case; (3) Unlike Left-Right Symmetric Models, the complex gauge fields $(W_1^{\prime }\mp i{W}_2^{\prime })$ (along with other complex scalar fields) associated with the $SU(2{)}_H$ do {\it not} carry electric charges, while the third component $W_3^{\prime }$ can mix with the hypercharge $U(1{)}_Y$ gauge field and the third component of $SU(2{)}_L$; (4) Absence of tree level flavour changing neutral current is guaranteed by gauge symmetry; and {\it etc}. In this work, we concentrate on the mass spectra of scalar and gauge bosons in the model. Constraints from previous $Z^{\prime }$ data at LEP and the Large Hadron Collider measurements of the Standard Model Higgs mass, its partial widths of $\gamma \gamma$ and $Z\gamma$ modes are discussed.

    hep-phJHEP(2016)·40 citations
18. 18*

    Decay law and time dilatation

    Francesco Giacosa🇩🇪

    We study the decay law for a moving unstable particle. The usual time-dilatation formula states that the decay width for an unstable state moving with a momentum $p$ and mass $M$ is ${\tilde{\Gamma }}_p=\Gamma M/\sqrt{p^2+M^2}$ with $\Gamma$ being the decay width in the rest frame. In agreement with previous studies, we show that in the context of QM as well as QFT this equation is \textit{not} correct provided that the quantum measurement is performed in a reference frame in which the unstable particle has momentum $p$ (note, a momentum eigenstate is \textit{not} a velocity eigenstate in QM). We then give, to our knowledge for the first time, an analytic expression of an improved formula and we show that the deviation from ${\tilde{\Gamma }}_p$ has a maximum for $p/M=\sqrt{2/3},$ but is typically \textit{very} small. Then, the result can be easily generalized to a momentum wave packet and also to an arbitrary initial state. Here, we give a very general expression of the non-decay probability. As a next step, we show that care is needed when one makes a boost of an unstable state with zero momentum/velocity: namely, the resulting state has zero overlap with the elements of the basis of unstable states (it is already decayed!). However, when considering a spread in velocity, one finds again that ${\tilde{\Gamma }}_p$ is typically a very good approximation. The study of a velocity wave-packet represents an interesting subject which constitutes one of the main outcomes of the present manuscript.\textbf{ }In the end, it should be stressed that there is no whatsoever breaking of special relativity, but as usual in QM, one should specify which kind of measurement on which kind of state is performed.

    hep-phquant-phActa Phys.Polon.B(2016)·20 citations
19. 19*

    Particle production in high-energy collisions beyond the shockwave limit

    Tolga Altinoluk🇪🇸 · Adrian Dumitru🇺🇸

    We compute next to eikonal (NE) and next to next to eikonal (NNE) corrections to the Lipatov vertex due to a finite target thickness. These arise from electric field insertions into the eikonal Wilson lines. We then derive a $k_T$-factorization formula for single inclusive gluon production at NNE accuracy and find that nuclear effects are absent. We also analyze NNE corrections to two-gluon production where some of the contributions are found to exhibit corrections proportional to $A^{2/3}$.

    hep-phnucl-thPRD(2016)·48 citations
20. 20*

    Schwinger Pair Production at Finite Temperature

    Leandro Medina🇺🇸 · Michael C. Ogilvie🇺🇸

    Thermal corrections to Schwinger pair production are potentially important in particle physics, nuclear physics and cosmology. However, the lowest-order contribution, arising at one loop, has proved difficult to calculate unambiguously. We show that this thermal correction may be calculated for charged scalars using the worldline formalism, where each term in the decay rate is associated with a worldline instanton. We calculate all finite-temperature worldline instantons, their actions and fluctuations prefactors, thus determining the complete one-loop decay rate at finite temperature. The thermal contribution to the decay rate becomes nonzero at a threshold temperature $T=eE/2m$, above which it dominates the zero temperature result. This is the lowest of an infinite set of thresholds at $T=neE/2m$. The decay rate is singular at each threshold as a consequence of the failure of the quadratic approximation to the worldline path integral. We argue that that higher-order effects will make the decay rates finite everywhere, and model those effects by the inclusion of hard thermal loop damping rates. We also demonstrate that the formalism developed here generalizes to the case of finite-temperature pair production in inhomogeneous fields.

    ↳ hep-thhep-phPRD(2017)·29 citations
21. 21*

    Wavelet-Based Techniques for the Gamma-Ray Sky

    Samuel D. McDermott🇺🇸 · Patrick J. Fox🇺🇸 · Ilias Cholis🇺🇸 · Samuel K. Lee🇺🇸

    We demonstrate how the image analysis technique of wavelet decomposition can be applied to the gamma-ray sky to separate emission on different angular scales. New structures on scales that differ from the scales of the conventional astrophysical foreground and background uncertainties can be robustly extracted, allowing a model-independent characterization with no presumption of exact signal morphology. As a test case, we generate mock gamma-ray data to demonstrate our ability to extract extended signals without assuming a fixed spatial template. For some point source luminosity functions, our technique also allows us to differentiate a diffuse signal in gamma-rays from dark matter annihilation and extended gamma-ray point source populations in a data-driven way.

    ↳ astro-ph.HEastro-ph.COastro-ph.IMhep-phJCAP(2016)·17 citations
22. 22*

    Chaos in Classical D0-Brane Mechanics

    Guy Gur-Ari🇺🇸 · Masanori Hanada🇺🇸 · Stephen H. Shenker🇺🇸

    We study chaos in the classical limit of the matrix quantum mechanical system describing D0-brane dynamics. We determine a precise value of the largest Lyapunov exponent, and, with less precision, calculate the entire spectrum of Lyapunov exponents. We verify that these approach a smooth limit as $N\to \infty$. We show that a classical analog of scrambling occurs with fast scrambling scaling, $t_{\ast }\sim \log S$. These results confirm the k-locality property of matrix mechanics discussed by Sekino and Susskind.

    ↳ hep-thhep-lathep-phJHEP(2016)·89 citations
23. 23*

    Relaxion Monodromy and the Weak Gravity Conjecture

    Luis E. Ibanez🇪🇸 · Miguel Montero🇪🇸 · Angel Uranga🇪🇸 · Irene Valenzuela🇩🇪

    The recently proposed relaxion models require extremely large trans-Planckian axion excursions as well as a potential explicitly violating the axion shift symmetry. The latter property is however inconsistent with the axion periodicity, which corresponds to a gauged discrete shift symmetry. A way to make things consistent is to use monodromy, i.e. both the axion and the potential parameters transform under the discrete shift symmetry. The structure is better described in terms of a 3-form field $C_{\mu \nu \rho }$ coupling to the SM Higgs through its field strength $F_4$. The 4-form also couples linearly to the relaxion, in the Kaloper-Sorbo fashion. The extremely small relaxion-Higgs coupling arises in a see-saw fashion as $g\simeq F_4/f$, with $f$ being the axion decay constant. We discuss constraints on this type of constructions from membrane nucleation and the Weak Gravity Conjecture. The latter requires the existence of membranes, whose too fast nucleation could in principle drive the theory out of control, unless the cut-off scale is lowered. This allows to constrain relaxion models on purely theoretical grounds. We also discuss possible avenues to embed this structure into string theory.

    ↳ hep-thhep-phJHEP(2016)·154 citations
24. 24*

    Ultraviolet and Infrared Divergences in Superstring Theory

    Ashoke Sen🇮🇳

    Superstring theory is known to be free from ultraviolet divergences but suffers from the usual infrared divergences that occur in quantum field theories. After briefly reviewing the origin of ultraviolet finiteness of superstring theory we describe recent progress towards the understanding of infrared divergences in superstring theory.

    ↳ hep-thgr-qchep-ph17 citations
25. 25*

    Structure of the $\Lambda (1405)$ and the $K^{-}d\to \pi \Sigma n$ reaction

    Shota Ohnishi🇯🇵 · Yoichi Ikeda🇯🇵 · Tetsuo Hyodo🇯🇵 · Wolfram Weise🇩🇪

    The $\Lambda (1405)$ resonance production reaction is investigated within the framework of the coupled-channels Alt-Grassberger-Sandhas (AGS) equations. We perform full three-body calculations for the $\bar{K}NN-\pi YN$ amplitudes on the physical real energy axis and investigate how the signature of the $\Lambda (1405)$ appears in the cross sections of the $K^{-}d\to \pi \Sigma n$ reactions, also in view of the planned E31 experiment at J-PARC. Two types of meson-baryon interaction models are considered: an energy-dependent interaction based on chiral $SU(3)$ effective field theory, and an energy-independent version that has been used repeatedly in phenomenological approaches. These two models have different off-shell properties that imply correspondingly different behavior in the three-body system. We investigate how these features show up in differential cross sections of $K^{-}d\to \pi \Sigma n$ reactions. Characteristic patterns distinguishing between the two models are found in the invariant mass spectrum of the final $\pi \Sigma$ state. The $K^{-}d\to \pi \Sigma n$ reaction, with different (${\pi }^{\pm }{\Sigma }^{\mp }$ and ${\pi }^0{\Sigma }^0$) charge combinations in the final state, is thus demonstrated to be a useful tool for investigating the subthreshold behavior of the $\bar{K}N$ interaction.

    ↳ nucl-thhep-phPRC(2016)·37 citations
26. 26*

    Hamiltonian effective field theory study of the ${\mathbf{N}}^{\ast }(1535)$ resonance in lattice QCD

    Zhan-Wei Liu🇦🇺 · Waseem Kamleh🇦🇺 · Derek B. Leinweber🇦🇺 · Finn M. Stokes🇦🇺 · Anthony W. Thomas🇦🇺 · Jia-Jun Wu🇦🇺

    Drawing on experimental data for baryon resonances, Hamiltonian effective field theory (HEFT) is used to predict the positions of the finite-volume energy levels to be observed in lattice QCD simulations of the lowest-lying $J^P=1/2^{-}$ nucleon excitation. In the initial analysis, the phenomenological parameters of the Hamiltonian model are constrained by experiment and the finite-volume eigenstate energies are a prediction of the model. The agreement between HEFT predictions and lattice QCD results obtained on volumes with spatial lengths of 2 and 3 fm is excellent. These lattice results also admit a more conventional analysis where the low-energy coefficients are constrained by lattice QCD results, enabling a determination of resonance properties from lattice QCD itself. Finally, the role and importance of various components of the Hamiltonian model are examined.

    ↳ hep-lathep-phnucl-thPRL(2016)·98 citations
27. 27*

    Dynamical net charge fluctuations at RHIC energies in STAR

    Bhanu Sharma (for the STAR Collaboration)🇮🇳

    We present preliminary results from the study of dynamical net-charge fluctuations measured in Au+Au collisions at $\sqrt{s_{NN}}$ = 39 GeV to 7.7 GeV and compare with the published results at higher collision energies. We also present the centrality dependence of the dynamical net-charge fluctuations.

    ↳ nucl-exhep-exhep-phPoS(2017)·3 citations
28. 28*

    Two-gluon rapidity correlations of strong colour field in $pp$, $pA$ and $AA$ collisions

    Ye-Yin Zhao🇨🇳 · Ming-Mei Xu🇨🇳 · Heng-Ying Zhang🇨🇳 · Yuan-Fang Wu🇨🇳

    Using the CGC formalism, we calculate the two-gluon rapidity correlations of strong colour fields in $pp$, $pA$ and $AA$ collisions, respectively. If one trigger gluon is fixed at central rapidity, a ridge-like correlation pattern is obtained in symmetry $pp$ and $AA$ collisions, and a huge bump-like correlation pattern is presented in asymmetry $pA$ collisions. It is demonstrated that the ridge-like correlation patterns are caused by the stronger correlation with the gluon of colour source. The transverse momentum and incident energy dependence of the ridge-like correlation pattern is also systematically studied. The ridge is more likely observed at higher incident energy and lower transverse momentum of trigger gluon.

    ↳ nucl-thhep-phNPA(2016)·5 citations
29. 29*

    Open EFTs, IR Effects and Late-Time Resummations: Systematic Corrections in Stochastic Inflation

    C.P. Burgess🇨🇦 · R. Holman🇺🇸 · G. Tasinato🇬🇧

    Though simple inflationary models describe the CMB well, their corrections are often plagued by infrared effects that obstruct a reliable calculation of late-time behaviour. We adapt to cosmology tools designed to address similar issues in other physical systems with the goal of making reliable late-time inflationary predictions. The main such tool is Open EFTs which reduce in the inflationary case to Stochastic Inflation plus calculable corrections. We apply this to a simple inflationary model that is complicated enough to have dangerous IR behaviour yet simple enough to allow the inference of late-time behaviour. We find corrections to standard Stochastic Inflationary predictions for the noise and drift, and we find these corrections ensure the IR finiteness of both these quantities. The late-time probability distribution, $\mathcal{P}(\varphi )$, for super-Hubble field fluctuations are obtained as functions of the noise and drift and so these too are IR finite. We compare our results to other methods (such as large-$N$ models) and find they agree when these models are reliable. In all cases we can explore in detail we find IR secular effects describe the slow accumulation of small perturbations to give a big effect: a significant distortion of the late-time probability distribution for the field. But the energy density associated with this is only of order $H^4$ at late times and so does {\em not} generate a dramatic gravitational back-reaction.

    ↳ gr-qcastro-ph.COhep-phhep-thJHEP(2016)·171 citations
30. 30*

    Role of $\omega$-meson exchange in scaling of the $\gamma p\to {\pi }^{0}p$ process from a Regge-type model with resonances

    Kook-Jin Kong🇰🇷 · Tae Keun Choi🇰🇷 · Byung-Geel Yu🇰🇷

    The scaling of photoproduction $\gamma p\to {\pi }^{0}p$ is investigated in the Reggeized model with $N^{\ast }$ and $\Delta$ resonances included to describe resonance peaks up to photon energy $E_{\gamma }$= 3 GeV. Given the $t$-channel exchanges $\rho (770)+\omega (780)+b_1(1235)+h_1(1170)$ Reggeized for the background contribution, the resonances of the Breit-Wigner form are introduced to agree with cross sections for total, differential and beam asymmetry in the low energy region. The scaled differential-cross sections $s^{7}d\sigma /dt$ are reproduced to agree with the recent JLab data, revealing the production mechanism of the big bump structure around $W\approx 2.2$ GeV by the deep-dip pattern of the $\omega$ exchange that originates from the zeros of the trajectory ${\alpha }_{\omega }(t)=0$ in the canonical phase, $\frac{1}{2}(-1+e^{-i\pi {\alpha }_{\omega }(t)})$.

    ↳ nucl-thhep-phPRC(2016)·4 citations
31. 31*

    Chiral symmetry breaking, instantons, and monopoles

    Adriano Di Giacomo🇮🇹 · Masayasu Hasegawa🇷🇺

    The purpose of this study is to show that monopoles induce the chiral symmetry breaking. In order to indicate the evidence, we add one pair of monopoles with magnetic charges to the quenched SU(3) configurations by a monopole creation operator, and investigate the propaties of the chiral symmetry breaking using the Overlap fermion. We show that instantons are created by the monopoles. The pseudoscalar meson mass and decay constant are computed from the correlation functions, and the renormalization constant $Z_S$ is determined by the non perturbative method. The renormalization group invariant chiral condensate in $\overline{\text{mbox}MS}$-scheme at 2 [GeV] is evaluated by the Gell-Mann-Oakes-Renner formula, and the random matrix theory. Finally, we estimate the renormalization group invariant quark masses $\bar{m}=(m_u+m_d)/2$, and $m_s$ in $\overline{\text{mbox}MS}$-scheme at 2 [GeV]. The preliminary results indicate that the chiral condensate decreases and the quark masses become slightly heavy by increasing the number of monopole charges.

    ↳ hep-lathep-phhep-thPoS(2016)·3 citations
32. 32*

    Holographic Three-Jet Events in Strongly Coupled N=4 Yang-Mills Plasma

    Jorge Casalderrey-Solana🇬🇧 · Andrej Ficnar🇬🇧

    We analyse classical string configurations with non-trivial transverse dynamics in $Ad{S}_5$-Schwarzschild. These strings develop kink-like structures which, via the gauge/gravity duality, can be interpreted as the propagation of hard gluons produced in association with a quark-antiquark pair in a strongly coupled $\mathcal{N}=4$ SYM plasma. We observe the appearance of two physically distinct regimes of the in-plasma dynamics, depending on whether the medium is able to resolve the transverse structure of the string prior to its total quench. From these studies we extract the medium resolution scale of the strongly coupled SYM plasma, defined as the smallest angular separation between two jets that the medium can resolve, ${\theta }_{\mathrm{res}}={\mathcal{C}}_{\mathrm{res}}(E/\sqrt{\lambda }T{)}^{-2/3}$, where ${\mathcal{C}}_{\mathrm{res}}=\frac{2^{4/3}}{\pi }\frac{\Gamma (3/4{)}^2}{\Gamma (5/4{)}^2}$. Our analysis constitutes the first study of proxies for three-jet events in a holographic context.

    ↳ hep-thhep-ph11 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.