Mon·Jun 26, 2017Monday·June 26, 2017

1. 01*

   The Dawn of FIMP Dark Matter: A Review of Models and Constraints

   Nicolás Bernal🇨🇴 · Matti Heikinheimo🇫🇮 · Tommi Tenkanen🇬🇧 · Kimmo Tuominen🇫🇮 · Ville Vaskonen🇪🇪

   We present an overview of scenarios where the observed Dark Matter (DM) abundance consists of Feebly Interacting Massive Particles (FIMPs), produced non-thermally by the so-called freeze-in mechanism. In contrast to the usual freeze-out scenario, frozen-in FIMP DM interacts very weakly with the particles in the visible sector and never attained thermal equilibrium with the baryon-photon fluid in the early Universe. Instead of being determined by its annihilation strength, the DM abundance depends on the decay and annihilation strengths of particles in equilibrium with the baryon-photon fluid, as well as couplings in the DM sector. This makes frozen-in DM very difficult but not impossible to test. In this review, we present the freeze-in mechanism and its variations considered in the literature (dark freeze-out and reannihilation), compare them to the standard DM freeze-out scenario, discuss several aspects of model building, and pay particular attention to observational properties and general testability of such feebly interacting DM.

   hep-phastro-ph.COInt.J.Mod.Phys.A(2017)·622 citations
2. 02*

   Gravity-Mediated Dark Matter Annihilation in the Randall-Sundrum Model

   Thomas D. Rueter🇺🇸 · Thomas G. Rizzo🇺🇸 · JoAnne L. Hewett🇺🇸

   Observational evidence for dark matter stems from its gravitational interactions, and as of yet there has been no evidence for dark matter interacting via other means. We examine models where dark matter interactions are purely gravitational in a Randall-Sundrum background. In particular, the Kaluza-Klein tower of gravitons which result from the warped fifth dimension can provide viable annihilation channels into Standard Model final states, and we find that we can achieve values of the annihilation cross section, $⟨\sigma v⟩$, which are consistent with the observed relic abundance in the case of spin-1 dark matter. We examine constraints on these models employing both the current photon line and continuum indirect dark matter searches, and assess the prospects of hunting for the signals of such models in future direct and indirect detection experiments.

   hep-phJHEP(2017)·42 citations
3. 03*

   A non-relativistic model for the $[cc][\bar{c}\bar{c}]$ tetraquark

   V. R. Debastiani🇪🇸 · F. S. Navarra🇧🇷

   We use a non-relativistic model to study the spectroscopy of a tetraquark composed of $[cc][\bar{c}\bar{c}]$ in a diquark-antidiquark configuration. By numerically solving the Schrödinger equation with a Cornell-inspired potential, we separate the four-body problem into three two-body problems. Spin-dependent terms (spin-spin, spin-orbit and tensor) are used to describe the splitting structure of the $c\bar{c}$ spectrum and are also extended to the interaction between diquarks. Recent experimental data on charmonium states are used to fix the parameters of the model and a satisfactory description of the spectrum is obtained. We find that the spin-dependent interaction is sizable in the diquark-antidiquark system, despite the heavy diquark mass, and also that the diquark has a finite size if treated in the same way as the $c\bar{c}$ systems. We find that the lowest $S$-wave $T_{4c}$ tetraquarks might be below their thresholds of spontaneous dissociation into low-lying charmonium pairs, while orbital and radial excitations would be mostly above the corresponding charmonium pair thresholds. Finally, we repeat the calculations without the confining part of the potential and obtain bound diquarks and bound tetraquarks. This might be relevant to the study of exotic charmonium in the quark-gluon plasma. The $T_{4c}$ states could be investigated in the forthcoming experiments at the LHC and Belle II.

   hep-phCPC(2019)·200 citations
4. 04*

   Resonant Higgs pair production as a probe of stop at the LHC

   Guang Hua Duan🇨🇳 · Lei Wu🇨🇳 · Rui Zheng🇺🇸

   Searching for top squark (stop) is a crucial task of the LHC. When the flavor conserving two body decays of the stop are kinematically forbidden, the stops produced near the threshold will live long enough to form bound states which subsequently decay through annihilation into the Standard Model (SM) final states. In the region of stop mixing angle ${\theta }_{\tilde{t}}\to 0$ or $\pi /2$, we note that the LHC-13 TeV diphoton resonance data can give a strong bound on the spin-$0$ stoponium (${\eta }_{\tilde{t}}$) and exclude the constituent stop mass $m_{\tilde{t}}$ up to about 290 GeV. While in the large stop mixing region, the stoponium will dominantly decay to the Higgs pair. By analyzing the process $pp\to {\eta }_{\tilde{t}}\to h(\to b\bar{b})h(\to {\tau }^{+}{\tau }^{-})$, we find that a large portion of the parameter space on the $m_{{\tilde{t}}_1}$ - ${\theta }_{\tilde{t}}$ plane can be probed at $2\sigma$ significance level at the LHC with the luminosity $\mathcal{L}=3000$ fb${}^{-1}$.

   hep-phhep-exJHEP(2017)·11 citations
5. 05*

   Are the B-anomalies evidence for heavy neutrinos?

   Xiao-Gang He🇨🇳 · German Valencia🇦🇺

   The existing anomalies appearing in decays of the form $b\to s{\ell }^{+}{\ell }^{-}$ constitute a possible hint for new physics. We point out that modifications to the SM results due to heavy neutrinos could account for the observed deviations while satisfying existing constraints from lepton flavor violating processes. The required mixing angle, however, is an order of magnitude larger than suggested by recent global fits to lepton flavor conserving processes. We frame our discussion in terms of a Type-I seesaw model, but it can be made more general.

   hep-ph9 citations
6. 06*

   Weibull Distribution and the multiplicity moments in $pp(p\bar{p})$ collisions

   Ashutosh Kumar Pandey🇮🇳 · Priyanka Sett🇮🇳 · Sadhana Dash🇮🇳

   A higher moment analysis of multiplicity distribution is performed using the Weibull description of particle production in $pp(p\bar{p})$ collisions at SPS and LHC energies. The calculated normalized moments and factorial moments of Weibull distribution are compared to the measured data. The calculated Weibull moments are found to be in good agreement with the measured higher moments (up to 5${}^{\mathrm{th}}$ order) reproducing the observed breaking of KNO scaling in the data. The moments for $pp$ collisions at $\sqrt{s}$ = 13 TeV are also predicted.

   hep-phPRD(2017)·9 citations
7. 07*

   Spontaneous CP violation in multi-Higgs potentials with triplets of $\Delta (3n^2)$ and $\Delta (6n^2)$

   Ivo de Medeiros Varzielas🇵🇹 · Stephen F. King🇬🇧 · Christoph Luhn🇩🇪 · Thomas Neder🇪🇸

   Motivated by discrete flavour symmetry models, we analyse Spontaneous CP Violation (SCPV) for potentials involving three or six Higgs fields (both electroweak doublets and singlets) which fall into irreducible triplet representations of discrete symmetries belonging to the $\Delta (3n^2)$ and $\Delta (6n^2)$ series, including $A_4$, $S_4$, $\Delta (27)$ and $\Delta (54)$. For each case, we give the potential and find various global mimima for different regions of the parameter space of the potential. Using CP-odd basis Invariants that indicate the presence of Spontaneous CP Violation we separate the VEVs into those that do or do not violate CP. In cases where CP is preserved we reveal a CP symmetry of the potential that is preserved by those VEVs, otherwise we display a non-zero CP-odd Invariant. Finally we identify interesting cases where there is Spontaneous Geometrical CP Violation in which the VEVs have calculable phases.

   hep-phJHEP(2017)·16 citations
8. 08*

   A CGC/saturation approach for angular correlations in proton-proton scattering

   E. Gotsman (Tel Aviv U.)🇮🇱 · E. Levin (Tel Aviv U./UTFSM)🇨🇱 · I. Potashnikova (UTFSM)🇨🇱

   We generalized our model for the description of hard processes, and calculate the value of the azimuthal angle correlations ( Fourier harmonics $v_n$ ), for proton-proton scattering.The energy and multiplicity independence, as well as the value of $v_n$, turn out the be in accord with the experimental data, or slightly larger. Therefore, before making extreme assumptions on proton-proton collisions, such as the production of quark-gluon plasma in the large multiplicity events, we need to explain how these effect theBose-Einstein correlations which are so large, that have to be taken into account, and which are able to describe the angular correlations in proton-proton collisions, without including final state interactions

   hep-phEPJC(2017)·11 citations
9. 09*

   Baryon Production at LHC Experiments: Average pt of Hyperons vs. Energy

   Olga I. Piskounova🇷🇺

   This paper examines the transverse momentum spectra of baryons in the multi-particle production at modern colliders using Quark-Gluon String Model (QGSM). It discusses 1) the difference in \Lambda^0 hyperon spectra at antiproton-proton vs. proton-proton reactions; 2) the growth of average transverse momenta of \Lambda hyperon with proton-proton collision energies and 3) the dependence of average p_t on the masses of mesons and baryons at the LHC energy 7 TeV. This analysis of baryon spectra led to the following conclusions. First, the fragmentation of antidiquark-diquark side of the pomeron diagram makes the major contribution to baryon production spectra in the asymmetric antiproton-proton reaction. Second, the average p_t's of hyperons steadily grow with energy on the range from 53 GeV to 7 TeV. Since no dramatic changes were seen in the characteristics of baryon production, the hadroproduction processes do not cause the "knee" in the cosmic ray proton spectra at the energies between Tevatron and LHC.

   hep-phInt.J.Mod.Phys.A(2020)·5 citations
10. 10*

    Approximate Alignment in Two Higgs Doublet Model with Extra Yukawa Couplings

    Wei-Shu Hou🇹🇼 · Mariko Kikuchi🇹🇼

    With discovery of the 125 GeV boson $h^0$, the existence of a second doublet is very plausible. We show that the "alignment" phenomenon, that $h^0$ is found to resemble closely the Standard Model Higgs boson, may correspond to Higgs quartic couplings ${\eta }_i$ that are $\mathcal{O}(1)$ in strength. If the exotic bosons of the second doublet possess extra top Yukawa couplings, which are the least constrained by data, such a two Higgs doublet model could drive electroweak baryogenesis, as well as further "protect" the apparent alignment. The exotic Higgs bosons can be sub-TeV in mass while remaining well hidden so far, with broad parameter space for search at the Large Hadron Collider.

    hep-phEPL(2018)·70 citations
11. 11*

    Spontaneous mirror left-right symmetry breaking for leptogenesis parametrized by Majorana neutrino mass matrix

    Pei-Hong Gu🇨🇳

    We introduce a mirror copy of the ordinary fermions and Higgs scalars for embedding the $SU(2{)}_L\times U(1{)}_Y$ electroweak gauge symmetry into an $SU(2{)}_L\times SU(2{)}_R\times U(1{)}_{B-L}$ left-right gauge symmetry. We then show the spontaneous left-right symmetry breaking can automatically break the parity symmetry motivated by solving the strong CP problem. Through the $SU(2{)}_R$ gauge interactions, a mirror Majorana neutrino can decay into a mirror charged lepton and two mirror quarks. Consequently we can obtain a lepton asymmetry stored in the mirror charged leptons. The Yukawa couplings of the mirror and ordinary charged fermions to a dark matter scalar then can transfer the mirror lepton asymmetry to an ordinary lepton asymmetry which provides a solution to the cosmic baryon asymmetry in association with the $SU(2{)}_L$ sphaleron processes. In this scenario, the baryon asymmetry can be well described by the neutrino mass matrix up to an overall factor.

    hep-phJHEP(2017)·11 citations
12. 12*

    Finite size effect of hadronic matter on its transport coefficients

    Subhasis Samanta🇮🇳 · Sabyasachi Ghosh🇮🇳 · Bedangadas Mohanty🇮🇳

    We have theoretically investigated the finite system size effect of hadronic matter on its transport coefficients like shear viscosity, bulk viscosity, and electrical conductivity. We have used a Hadron Resonance Gas (HRG) model to calculate the thermodynamical quantities like entropy density, speed of sound and also the above transport coefficients. All these quantities are found to be sensitive to finite system size effects of hadronic matter. The effect of finite system size is found to be more when the system is at low temperatures and gets reduced at high temperatures. Owing to the intimate linking between system size and centrality, we have presented the centrality dependence of transport coefficients. We have also explored to link of our results with the macroscopic picture of hydrodynamical evolution.

    hep-phnucl-thJ.Phys.G(2018)·28 citations
13. 13*

    Tetraquarks in holographic QCD

    Thomas Gutsche🇩🇪 · Valery E. Lyubovitskij🇩🇪 · Ivan Schmidt🇨🇱

    Using a soft-wall AdS/QCD approach we derive the Schrödinger-type equation of motion for the tetraquark wave function, which is dual to the dimension-4 AdS bulk profile. The latter coincides with the number of constituents in the leading Fock state of the tetraquark. The obtained equation of motion is solved analytically, providing predictions for both the tetraquark wave function and its mass. A low mass limit for possible tetraquark states is given by $M\ge 2\kappa =1$ GeV, where $\kappa =0.5$ GeV is the typical value of the scale parameter in soft-wall AdS/QCD. We confirm results of the COMPASS Collaboration recently reported on the discovery of the $a_1(1414)$ state, interpreted as a tetraquark state composed of light quarks and having $J^{PC}=1^{++}$. Our prediction for the mass of this state, $M_{a_1}=\sqrt{2}$ GeV $\simeq 1.414$ GeV, is in good agreement with the COMPASS result $M_{a_1}=1.414_{-0.013}^{+0.015}$ GeV. Next we included finite quark mass effects, which are essential for the tetraquark states involving heavy quarks.

    hep-phPRD(2017)·25 citations
14. 14*

    Extending the Universal One-Loop Effective Action: Heavy-Light Coefficients

    Sebastian A. R. Ellis🇺🇸 · Jérémie Quevillon🇬🇧 · Tevong You🇬🇧 · Zhengkang Zhang🇺🇸

    The Universal One-Loop Effective Action (UOLEA) is a general expression for the effective action obtained by evaluating in a model-independent way the one-loop expansion of a functional path integral. It can be used to match UV theories to their low-energy EFTs more efficiently by avoiding redundant steps in the application of functional methods, simplifying the process of obtaining Wilson coefficients of operators up to dimension six. In addition to loops involving only heavy fields, matching may require the inclusion of loops containing both heavy and light particles. Here we use the recently-developed covariant diagram technique to extend the UOLEA to include heavy-light terms which retain the same universal structure as the previously-derived heavy-only terms. As an example of its application, we integrate out a heavy singlet scalar with a linear coupling to a light doublet Higgs. The extension presented here is a first step towards completing the UOLEA to incorporate all possible structures encountered in a covariant derivative expansion of the one-loop path integral.

    hep-phhep-thJHEP(2017)·98 citations
15. 15*

    The role of the $S_3$ GUT leptoquark in flavor universality and collider searches

    Ilja Doršner🇭🇷 · Svjetlana Fajfer🇸🇮 · Darius A. Faroughy🇸🇮 · Nejc Košnik🇸🇮

    We investigate the ability of the $S_3$ scalar leptoquark to address the recent hints of lepton universality violation in $B$ meson decays. The $S_3$ leptoquark with quantum numbers $(\overline{3},3,1/3)$ naturally emerges in the context of an $SU(5)$ GUT model without any conflict with the stringent limits from observed nucleon stability. Scalar leptoquark $S_3$ with left-handed couplings to 2nd and 3rd generations of charged leptons and down-type quarks seems well-suited to address both $R_{K^{(\ast )}}$ and $R_{D^{(\ast )}}$. We quantify this suitability with numerical fits to a plethora of relevant flavor observables. The proposed $SU(5)$ model calls for a second leptoquark state, i.e., ${\tilde{R}}_2$ with quantum numbers $(3,2,1/6)$, if one is to generate gauge coupling unification and neutrino mass. We accordingly include it in our study to investigate ${\tilde{R}}_2$'s ability to offset adverse effects of $S_3$ and thus improve a quality of numerical fits. A global fit of the leptoquark Yukawa couplings shows that large couplings of light $S_3$ to $\tau$ leptons are preferred. We furthermore identify $B\to K^{(\ast )}\bar{\nu }\nu$ as the most sensitive channel to probe the preferred region of parameter space. Large couplings of $S_3$ to $\tau$ leptons are finally confronted with the experimental searches for $\tau$ final states at the Large Hadron Collider. These searches comprise a study of decay products of the leptoquark pair production, as well as, and more importantly, an analysis of the high-mass $\tau \tau$ final states.

    hep-phJHEP(2017)·127 citations
16. 16*

    Direct CP asymmetry in $D\to {\pi }^{-}{\pi }^{+}$ and $D\to K^{-}{K}^{+}$ in QCD-based approach

    Alexander Khodjamirian🇩🇪 · Alexey A. Petrov🇺🇸

    We present the first QCD-based calculation of hadronic matrix elements with penguin topology determining direct CP-violating asymmetries in $D^0\to {\pi }^{-}{\pi }^{+}$ and $D^0\to K^{-}{K}^{+}$ nonleptonic decays. The method is based on the QCD light-cone sum rules and does not rely on any model-inspired amplitude decomposition, instead leaning heavily on quark-hadron duality. We provide a Standard Model estimate of the direct CP-violating asymmetries in both pion and kaon modes and their difference and comment on further improvements of the presented computation.

    hep-phhep-exPLB(2017)·107 citations
17. 17*

    Strangeness chemical potential from the baryons relative to the kaons particle ratios

    Abdel Nasser Tawfik (Egyptian Ctr. Theor. Phys., Cairo, WLCAPP, Cairo)🇪🇬 · Magda Abdel Wahab🇪🇬 · Hayam Yassin🇪🇬 · Eman R. Abo Elyazeed (Ain Shams U., Cairo)🇪🇬 · Hadeer M. Nasr El Din (Modern Academy for Engineering, Cairo, WLCAPP, Cairo)🇪🇬

    From a systematic analysis of the energy-dependence of four antibaryon-to-baryon ratios relative to the antikaon-to-kaon ratio, we propose an alternative approach determining the strange-quark chemical potential (${\mu }_{\mathrm{s}}$). It is found that ${\mu }_{\mathrm{s}}$ generically genuinely equals one-fifth the baryon chemical potential (${\mu }_{\mathrm{b}}$). An additional quantity depending on ${\mu }_{\mathrm{b}}$ and the freezeout temperature ($T$) should be added in order to assure averaged strangeness conversation. This quantity gives a genuine estimation for the possible strangeness enhancement with the increase in the collision energy. At the chemical freezeout conditioned to constant entropy density normalized to temperature cubed, various particle ratios calculated at $T$ and ${\mu }_{\mathrm{b}}$ and the resultant ${\mu }_{\mathrm{s}}$ excellently agree with the statistical-thermal calculations.

    hep-phIJMPE(2017)·2 citations
18. 18*

    B-physics anomalies: a guide to combined explanations

    Dario Buttazzo🇨🇭 · Admir Greljo🇨🇭 · Gino Isidori🇨🇭 · David Marzocca🇨🇭

    Motivated by additional experimental hints of Lepton Flavour Universality violation in B decays, both in charged- and in neutral-current processes, we analyse the ingredients necessary to provide a combined description of these phenomena. By means of an Effective Field Theory (EFT) approach, based on the hypothesis of New Physics coupled predominantly to the third generation of left-handed quarks and leptons, we show how this is possible. We demonstrate, in particular, how to solve the problems posed by electroweak precision tests and direct searches with a rather natural choice of model parameters, within the context of a $U(2{)}_q\times U(2{)}_{\ell }$ flavour symmetry. We further exemplify the general EFT findings by means of simplified models with explicit mediators in the TeV range: coloured scalar or vector leptoquarks and colour-less vectors. Among these, the case of an $SU(2{)}_L$-singlet vector leptoquark emerges as a particularly simple and successful framework.

    hep-phhep-exJHEP(2017)·553 citations
19. 19*

    Solving the $\hat{q}$ puzzle with $x$ and scale dependence

    Amit Kumar🇺🇸 · Evan Bianchi🇺🇸 · Jacob Elledge🇺🇸 · Abhijit Majumder🇺🇸 · Guang-You Qin🇨🇳 · Chun Shen🇺🇸

    We present here a possible resolution of the jet quenching parameter $\hat{q}$ puzzle by exploring the momentum fraction $x$ and scale $Q^2$ dependence of $\hat{q}$, in addition to temperature dependence. We explore the momentum broadening of the jet due to Glauber gluon exchange with the quark-gluon plasma (QGP). This has led us to define the momentum fraction $x$ for the partons in the QGP. We also show here, for the first time, possible forms of the parton distribution function (PDF) of the QGP. The QGP-PDF as input in $\hat{q}$ has been used to fit the PHENIX and CMS data simultaneously. We observe that the scale evolution of the QGP-PDF and the energy of the jet are the missing ingredients responsible for the enhancement of $\hat{q}$ at the same temperature in RHIC collisions compared to LHC collisions.

    ↳ nucl-thhep-phNPA(2017)·12 citations
20. 20*

    New ISR Cross Section Results on $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{\pi }^0{\pi }^0$ and $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}\eta$ from BaBar

    Konrad Griessinger (for the BaBar Collaboration)🇩🇪

    Two new hadronic cross sections measured by the BaBar experiment are presented: $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{\pi }^0{\pi }^0$ and $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}\eta$. For both channels, the contribution the anomalous magnetic moment of the muon is calculated.

    ↳ hep-exhep-phNucl.Part.Phys.Proc.(2017)·34 citations
21. 21*

    Three-particle quantization condition in a finite volume: 1. The role of the three-particle force

    H.-W. Hammer🇩🇪 · J.-Y. Pang🇩🇪 · A. Rusetsky🇩🇪

    Using non-relativistic effective Lagrangians in the particle-dimer picture, we rederive the expression for the energy shift of a loosely bound three-particle bound state of identical bosons in the unitary limit. The effective field theory formalism allows us to investigate the role of the three-particle force, which has not been taken into account in the earlier treatment of the problem. Moreover, we are able to relax the requirement of the unitary limit of infinite scattering length and demonstrate a smooth transition from the weakly bound three-particle state to a two-particle bound state of a particle and a deeply bound dimer.

    ↳ hep-lathep-phnucl-thJHEP(2017)·188 citations
22. 22*

    The Neutrino Signal From Pair Instability Supernovae

    Warren P. Wright🇺🇸 · Matthew S. Gilmer🇺🇸 · Carla Fröhlich🇺🇸 · James P. Kneller🇺🇸

    A very massive star with a carbon-oxygen core in the range of $64$ M${}_{\odot }<M_{\mathrm{CO}}<133$ M${}_{\odot }$ is expected to undergo a very different kind of explosion known as a pair instability supernova. Pair instability supernovae are candidates for superluminous supernovae due to the prodigious amounts of radioactive elements they create. While the basic mechanism for the explosion is understood, how a star reaches a state is not, thus observations of a nearby pair-instability supernova would allow us to test current models of stellar evolution at the extreme of stellar masses. Much will be sought within the electromagnetic radiation we detect from such a supernova but we should not forget that the neutrinos from a pair-instability supernova contain unique signatures of the event that unambiguously identify this type of explosion. We calculate the expected neutrino flux at Earth from two, one-dimensional pair-instability supernova simulations which bracket the mass range of stars which explode by this mechanism taking into account the full time and energy dependence of the neutrino emission and the flavor evolution through the outer layers of the star. We calculate the neutrino signals in five different detectors chosen to represent present or near future designs. We find the more massive progenitors explode as pair-instability supernova which can easily be detected in multiple different neutrino detectors at the `standard' supernova distance of $10\mathrm{kpc}$ producing several events in DUNE, JUNE and SuperKamiokande, while the lightest progenitors only produce a handful of events (if any) in the same detectors. The proposed HyperKamiokande detector would detect neutrinos from a large pair-instability supernova as far as $\sim 50\mathrm{kpc}$ allowing it to reach the Megallanic Clouds and the several very high mass stars known to exist there.

    ↳ astro-ph.HEastro-ph.SRhep-phPRD(2017)·12 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.