The Bose-Einstein correlation (BEC) in forward region ($2.0<η<4.8$) measured at 7 TeV in the Large Hadron Collider (LHC) by the LHCb collaboration is analyzed using two conventional formulas of different types named CF$_{\rm I}$ and CF$_{\rm II}$. The first formula is well known and contains the degree of coherence ($λ$) and the exchange function $E_{\rm BE}^2$ from the BE statistics. The second formula is an extended formula (CF$_{\rm II}$) that contains the second degree of coherence $λ_2$ and the second exchange function $E_{\rm BE_2}^2$ in addition to CF$_{\rm I}$. To examine the physical meaning of the parameters estimated by CF$_{\rm II}$, we analyze the LHCb BEC data by using a stochastic approach of the three-negative binomial distribution and the three-generalized Glauber-Lachs formula. Our results reveal that the BEC at 7 TeV consisted of three activity intervals defined by the multiplicity $n$ ([8, 18], [19, 35], and [36, 96]) can be well explained by CF$_{\rm II}$.
Comparing the expected spectroscopy in the relativistic quark model and the predicted strong decays in the $^3P_0$ model employing the realistic wave functions from the relativistic quark model with the measured properties of the LHCb and BaBar charmed states, we find that the masses and strong decays of these charmed states can be reasonably explained in the conventional $q\bar{q}$ picture, and therefore suggest that the $D(2550)$/$D_J(2580)$, $D^*(2600)$/$D^*_J(2650)$, $D(2750)$/$D_J(2740)$, $D^*(2760)$/$D^*_J(2760)$, $D_J(3000)$, and $D^*_J(3000)$ can be identified as the $D(2^1S_0)$, $D(2^…
The most recent results on CP violation in $b$ hadrons obtained by the LHCb Collaboration with Run I and years 2015-2016 of Run II are reviewed. The different types of violation are covered by the studies presented in this paper.
LHCb collaboration measured CPV at the level of one percent in the difference of assymetries in $D^0(\bar D^0)\to π^+ π^-, K^+ K^-$ decays. If confirmed on a larger statistics and final systematics this would mean New Physics manifestation. The fourth quark-lepton generation can be responsible for the observed effect.
Quit recently, two sets of new experimental data from the $LHCb$ and the $CMS$ collaborations have been published, concerning the production of the $Z^0$ vector boson in hadron-hadron collisions with the center-of-mass energy $E_{CM}= \sqrt{s}=13\;TeV$. On the other hand, in our recent work, we have conducted a set of $NLO$ calculations for the production of the electroweak gauge vector bosons, utilizing the unintegrated parton distribution functions ($UPDF$) in the frameworks of $Kimber$-$Martin$-$Ryskin$ ($KMR$) or $Martin$-$Ryskin$-$Watt$ ($MRW$) and the $k_t$-factorization formalism, concl…
The LHCb collaboration recently announced preliminary evidence for CP violation in D meson decays. We discuss this result in the context of the standard model (SM), as well as its extensions. In the absence of reliable methods to evaluate the hadronic matrix elements involved, we can only estimate qualitatively the magnitude of the non-SM tree level operators required to generate the observed central value. In the context of an effective theory, we list the operators that can give rise to the measured CP violation and investigate constraints on them from other processes.
The recent measurement of $ΔA_{CP}$ by the LHCb collaboration requires an ${\cal O}(10)$ enhancement coming from hadronic physics in order to be explained within the SM. We examine to what extent can NP models explain $ΔA_{CP}$ without such enhancements. We discuss the implications in terms of a low energy effective theory as well as in the context of several explicit NP models.
We discuss the interpretation of the $J\!/\!ψ\,J\!/\!ψ$ peak recently seen by the LHCb collaboration at CERN, and take the opportunity to review the experimental and theoretical state of the art for exotic hadrons. It is stressed that in constituent models, the states in the continuum require a dedicated treatment to single out resonances atop the continuum.
Inspired by recent measurement of possible fully charmed tetraquarks in LHCb Collaboration, we investigate the mass spectra of fully heavy tetraquarks $QQ \bar Q \bar Q$ in an extended relativized quark model. Our estimations indicate that the broad structure around 6.4 GeV should contain one or more ground $cc \bar c \bar c$ tetraquark states, while the narrow structure near 6.9 GeV can be categorized as the first radial excitation of $cc \bar c \bar c$ system. Moreover, with the wave functions of the tetraquarks and mesons, the strong decays of tetraquarks into heavy quarkonium pair are qual…
A large CP asymmetry predicted recently in the framework of the QCD factorization model for the B+- --> K+- K+ K- decays in the range of the K+ K- invariant masses above the phi(1020) resonance has been confirmed by the LHCb Collaboration. We discuss the emergence and size of this asymmetry in an extended model involving S- and P-waves together with the contribution from the D-wave f2(1270) resonance and compare our model with the experimental data of the LHCb and BABAR Collaborations.
The two exotic $P_c^+(4380)$ and $P_c^+(4450)$ discovered in $2015$ by the LHCb Collaboration, together with the four resonances $X(4140)$, $X(4274)$, $X(4500)$ and $X(4700)$, reported in $2016$ by the same collaboration, are described in a constituent quark model which has been able to explain the properties of charmonium states from the $J/ψ$ to the $X(3872)$. Using this model we found a $\bar DΣ_c^*$ bound state with $J^P=\frac{3}{2}^-$ that may be identified with the $P_c^+(4380)$. In the $\bar D^*Σ_c$ channel we found three possible candidates for the $P_c^+(4450)$ with $J^P=\frac{1}{2}^-…
We study the bottom $Λ_b(6146)^0$ baryon, newly discovered by the LHCb Collaboration. By adopting an interpolating current of $(L_ρ, L_λ)=(0,2)$ type and $D$-wave nature with spin-parity quantum numbers $J^P=\frac{3}{2}^+$ for this heavy bottom baryon, we calculate its mass and residue. Using these spectroscopic parameters, we also investigate its dominant decays $Λ_b(6146)^0\rightarrowΣ_bπ$ and $Λ_b(6146)^0\rightarrowΣ^*_bπ$ and estimate the width of $Λ_b(6146)^0$ obtained via these channels. The obtained mass, $m_{Λ_b}=(6144\pm 68)$~MeV is in accord nicely with the experimental data. The wid…
We study the experimental $DK$ invariant mass spectra of the reactions $B^+ \to \bar{D}^0 D^0 K^+$, $B^0 \to D^- D^0 K^+$ (measured by the BaBar Collaboration) and $B_s \to π^+ \bar{D}^0 K^-$ (measured by the LHCb Collaboration), where an enhancement right above the threshold is seen. We show that this enhancement is due to the presence of $D^\ast_{s0}(2317)$, which is a $DK$ bound state in the $I(J^P) = 0(0^+)$ sector. We employ a unitarized amplitude with an interaction potential fixed by heavy meson chiral perturbation theory. We obtain a mass $M_{D^\ast_{s0}} = 2315^{+12}_{-17}\ ^{+10}_{-5…
Inspired by the recent observations of the vector charmonium-like states at BES III Collaboration and $ψ(3842)$ at LHCb Collaboration, we comb the $D$ wave charmonium state in the present work. We first evaluate the possibility of $Y(4320)$ as $ψ(3^3D_1)$ by investigating its open charm decays in quark-pair creation model and we find the width of $Y(4320)$ can be reproduced in a reasonable parameter range. Moreover, we take $ψ(3770)$, $ψ(4160)$ and $Y(4320)$ as the scale of $1D$, $2D$ and $3D$ charmonia to estimate the open charm decays of other $D$ wave charmonia. The total and partial widths…
LHCb collaboration has recently announced a measurement of the difference of time-integrated CP asymmetries between $D\rightarrow K^+K^-$ and $D \rightarrow π^+π^-$. This result provides the evidence of large direct CP violation in $D$ meson and reveals some important implications on underlying new physics. It is shown that the direct CP violation in $D$ meson can be enhanced by R-parity violating supersymmetry, while CP violations in $K$ and $B$ mesons are suppressed by this new physics, which is in consistence with previous experiments. Constraints on the model parameters and some consequenc…
In this contribution we study the nature of the new Pc$(4312)^+$ signal reported by LHCb collaboration in the $J/ψ\,p$ spectrum. We use $S$-matrix principles to perform a minimum-bias analysis of the data, focusing on the analytic properties that can be related to the microscopic origin of the Pc$(4312)^+$ peak. Using the scattering length approximation we find evidence for interpretation of the signal as a virtual state generated by the attractive effect of the $Σ_c^+ \bar{D}^0$ channel opening.
The newly reported exotic signal $Z_c(4100)$ by the LHCb Collaboration in the invariant mass spectrum of $η_cπ^-$ in $B^0\to η_c K^+ π^-$ has been a new experimental evidence for an exotic meson containing four constituent quarks. Although the present experimental information is very limited, we show that its correlations with some existing exotic candidates can be recognized. This signal can be either caused by final state interaction effects or a $P$-wave resonance state arising from the $D^*\bar{D}^*$ interaction. For the latter option its neutral partner will have exotic quantum numbers of…
We consider the ${\bar D}^{(*)}Σ_c^{(*)}$ states, together with $J/ψN$ and other coupled channels, and take an interaction consistent with heavy quark spin symmetry, with the dynamical input obtained from an extension of the local hidden gauge approach. By fitting only one parameter to the recent three pentaquark states reported by the LHCb collaboration, we can reproduce the three of them in base to the mass and the width, providing for them the quantum numbers and approximate molecular structure as $1/2^-$ $\bar{D} Σ_c$, $1/2^-$ $\bar{D}^* Σ_c$, and $3/2^-$ $\bar{D}^* Σ_c$, and isospin $I=1/…
We discuss some new aspects of charm production trigerred by recent observations of the LHCb collaboration. The LHCb collaboration measured small asymmetries in production of $D^+ D^-$ mesons as well as $D_s^+ D_s^-$ mesons. Is this related to initial quark/antiquark asymmetries in the proton ? Here we discuss a scenario in which unfavored fragmentations $q/{\bar q} \to D$ and $s/{\bar s} \to D_s$ are responsible for the asymmetries. We fix the strength of such fragmentations -- transition probabilities, by adjusting to the size of the LHCb asymmetries. This has consequences for production of …
We can obtain a second conventional formula (${\rm CF_{II}}$) with two components by extending the conventional formula ${\rm CF_{I}}$ with one component for Bose-Einstein Correlation (BEC). We used ${\rm CF_{II}}$ to analyze the BEC at $Z^0$-pole as part of the OPAL collaboration. $R_1({\rm G})=0.91\pm 0.03$ fm ($λ_1=0.61\pm 0.03$) and $R_2({\rm G})=2.57\pm 0.44$ fm ($λ_1=0.35\pm 0.09$) are the estimated interaction region, where $λ_1$ and $λ_2$ are the degrees of coherence, and G is the Gaussian distribution, respectively. Long range correlation (LRC) is also studied.
Recently, the LHCb Collaboration reported pronounced structures in the invariant mass spectrum of $J/ψ$-pairs produced in proton-proton collisions at the Large Hadron Collider. In this Letter, we argue that the data can be very well described within two variants of a coupled-channel approach employing $T$-matrices consistent with unitarity: (i) with just two channels, $J/ψJ/ψ$ and $ψ(2S)J/ψ$, as long as energy-dependent interactions in these channels are allowed, or (ii) with three channels $J/ψJ/ψ$, $ψ(2S)J/ψ$ and $ψ(3770)J/ψ$ with just constant contact interactions. Both formulations hint at…
We comment on the recent evidence by the LHCb Collaboration for a structure in the $J/ψΛ$ final state produced in the decay $Ξ^-_b \to J/ψΛK^-$, with minimal quark content $c \bar c u d s$.
The D0 collaboration has announced the observation of the like-sign dimuon charge asymmetry since 2010, which has more than 3σdeviation from the Standard Model prediction. One of the promising explanation is considering the existence of flavor changing Z' couplings to the b and s quarks which can contribute to the off-diagonal decay width in the B_s - \bar{B}_s mixing. Model construction is highly constrained by the recent LHCb data of 1fb^{-1} integrated luminosity . In this paper, we analyze the experimental constraints in constructing new physics models to explain the dimuon charge asymmetr…
Inspired by the recent observations of $T_{c\bar{s}0}^{0/++}$ in the the processes $B^0\to\bar{D}^0 D_s^+ π^-$ and $B^+\to D^- D_s^+ π^+$ by LHCb Collaboration, we investigate the decay properties of the $T_{c\bar{s}0}^{0}$ in a $D^{*}K^{*}$ molecule scenario, and the widths of $T_{c\bar{s}0}^{0}\to D^{0}K^{0}$, $D_{s}^{+}π^{-}$, $D_{s}^{*+}ρ^{-}$, $D_{s1}^{(\prime)+}π^{-}$, and $D^{*0}(Dπ)^{0}$ are estimated. Our estimations indicate that the width of $T_{c\bar{s}0}^{0} \to D_s^+ π^-$ is sizable to be observed and the dominant decay mode of $T_{c\bar{s}0}^{0}$ is $D^0K^0$. Considering the iso…
Using the negative binomial distribution (NBD) and the generalized Glauber-Lachs (GGL) formula, we analyze the data on charged multiplicity distributions with pseudo-rapidity cutoffs η_c at 0.9, 2.36, and 7 TeV by ALICE Collaboration and at 0.2, 0.54, and 0.9 TeV by UA5 Collaboration. We confirm that the KNO scaling holds among the multiplicity distributions with η_c = 0.5 at \sqrt{s} = 0.2\sim2.36 TeV and estimate the energy dependence of a parameter 1/k in NBD and parameters 1/k and γ(the ratio of the average value of the coherent hadrons to that of the chaotic hadrons) in the GGL formula. U…
Encouraged by a recent observation of the B_c^+ -> B_s^0 + pi^+ decay by the LHCb collaboration we present the meson dominance predictions for other weak decays of the B_c^+ into B_s^0 or B^0 in the form of branching ratios to the observed decay.
We study triple-parton scattering effects in open charm production in proton-proton collisions at the LHC. Predictions for one, two and three $c\bar c$ pairs production are given for $\sqrt{s}= 7$ TeV and $\sqrt{s}= 13$ TeV. Quite large cross sections, of the order of milibarns, for the triple-parton scattering mechanism are obtained. We suggest a measurement of three $D^{0}$ or three $\bar{D^{0}}$ mesons by the LHCb collaboration. The predicted visible cross sections are of the order of a few nanobarns. The counting rates including $D^{0} \to K^{-}π^{+}$ branching fractions are also given. We…
We compare and analyse Bose-Einstein correlation data for $π^+ p$ and $K^+ p$ collisions at $\sqrt{s}=22\ GeV$ obtained by the NA22-Collaboration and data for $p\bar{p}$ collisions at $\sqrt{s}=630\ GeV$ obtained by the UA1-Minimum-Bias-Collaboration. Using a parametrization for a longitudinally expanding source, we observe that correlation lengths and radii extracted from fits to the data change significantly if one goes from the NA22- to the UA1-data: the transverse radius of the chaotic source increases by about $50\%$ while the correlation lengths in longitudinal and transverse directions …
This study aims to analyze the data on multiplicity distributions and Bose-Einstein correlations collected at the LHC by the ATLAS and CMS Collaborations using a double-generalized Glauber-Lachs formula (D-GGL) and double-negative binomial distribution (D-NBD). From this investigation, it can be inferred that the D-GGL formula performs as effectively as the D-NBD. Moreover, our results show that the parameters estimated in multiplicity distributions (MD) (P(n)) are related to those contained in the BEC formula.
A recent analysis by the LHCb collaboration suggests the existence of three narrow pentaquark-like states --- the $P_c(4312)$,$P_c(4440)$ and $P_c(4457)$ --- instead of just one in the previous analysis (the $P_c(4450)$). The closeness of the $P_c(4312)$ to the $\bar{D} Σ_c$ threshold and the $P_c(4440)$/$P_c(4457)$ to the $\bar{D}^* Σ_c$ one suggests a molecular interpretation of these resonances. We show that these three pentaquark-like resonances can be naturally accommodated in a contact-range effective field theory description that incorporates heavy-quark spin symmetry. This description …
We investigate the structure $X(4630)$ discovered by the LHCb collaboration in the process $B^{+}\rightarrow J/ψϕK^{+}$ as a resonance in the $ J/ψϕ$ mass distribution. We explore this resonance as a diquark-antidiquark state $X=[cs][\overline{c}\overline{s}]$ with spin-parities $J^{\mathrm{PC}}=1^{-+}$. Its mass and current coupling are calculated using the QCD two-point sum rule method by taking into account vacuum condensates up to dimension $10$. We also study decays of this tetraquark to mesons $J/ψϕ$, $η_{c}η^{(\prime )}$, and $χ_{c1}η^{(\prime )}$, and compute partial widths of these ch…
We applied an improved Coulomb correction method developed by us recently to data on identical KK-pairs production in S + Pb and p + Pb reactions at 200 GeV/c obtained by NA44 Collaboration. To analyse the whole range of the momentum transfers measured the method of "seamless fitting" has been proposed and used together with the asymptotic expansion formula for the Coulomb wave function. We found that such Coulomb corrections lead sometimes to different than previously reported (by NA44 Collaboration) interaction region and strongly influence the long range correlations.
We review the current status of theoretical predictions for mixing quantities and lifetimes in the $B$-sector. In particular, due to the first non-zero measurement of the decay rate difference in the neutral $B_s$-system, $ΔΓ_s/ Γ_s = 17.6 % \pm 2.9 %$ by the LHCb collaboration and very precise data for $τ_{B_s}$ from TeVatron and LHCb our theoretical tools can now be rigorously tested and it turns out that the Heavy Quark Expansion works in the $B$-system to an accuracy of at least 30% for quantities like $Γ_{12}$, which is most sensitive to hypothetical violations of quark hadron duality. Th…
Following updated and extended measurements of the full angular distribution of the decay $Λ_b\to Λ(\to p\,π^-)μ^+μ^-$ by the LHCb collaborations, as well as a new measurement of the $Λ\to p π^-$ decay asymmetry parameter by the BESIII collaboration, we study the impact of these results on searches for non-standard effects in exclusive $b\to sμ^+μ^-$ decays. To this end, we constrain the Wilson coefficients $\mathcal{C}_{9}$ and $\mathcal{C}_{10}$ of the numerically leading dimension-six operators in the weak effective Hamiltonian, in addition to the relevant nuisance parameters. In stark cont…
We analyse the deuteron-like $T^+_{cc}$ state observed by the LHCb Collaboration from the perspective of the quark clustering. The $T^+_{cc}$ state implies the possible existence of other compact doubly heavy tetraquark states.
The multiplicity distribution and the two-particle Bose-Einstein correlations at fixed multiplicities observed in $pp$ collisions at $\sqrt{s}=7$ TeV by the ALICE Collaboration are analyzed by the formulae obtained in the quantum optical approach. The chaoticity parameters in the inclusive and semi-inclusive events are estimated from the analysis. Multiplicity or $k_T$ dependence of longitudinal and transverse source radii are also estimated.
In recent years, the LHCb collaboration has published results on the measurement of several observables associated to semileptonic $b \to s$ transitions. Interestingly, various deviations from their expected values in the Standard Model have been found, including some tantalizing hints pointing towards the violation of Lepton Flavor Universality. We discuss New Physics models that address these anomalies and explore their possible connection to the dark matter of the Universe.
Analyses of Bose-Einstein Correlations in $\rW^{+}\rW^{-}$ events at LEP2 by the four LEP collaborations are presented. In particular, Bose-Einstein correlations in $\rW^{+}\rW^{-}$ overlap are investigated and the possible existence of these correlations between particles coming from different W's, which may influence the W-mass measurements in the fully hadronic channel $\re^{+}\re^{-}\to \rW^{+}\rW^{-}\to\rq_1 \bar{\rq}_2 \rq_3 \bar{\rq}_4 $. No evidence for such an inter-W Bose-Einstein correlation is found. The results are preliminary.
Using the negative binomial distribution (NBD) and the generalized Glauber-Lachs (GGL) formula, we analyze the data on charged multiplicity distributions in the several pseudorapidity intervals |η| < η_c at 0.2 - 7 TeV by UA5 and ALICE Collaborations. We confirm that the KNO scaling holds among the multiplicity distributions with η_c = 0.5 at \sqrt{s} = 0.2 - 2.36 TeV and estimate the energy dependence of a parameter 1/k in NBD and parameters 1/k and γ(the ratio of the average value of the coherent hadrons to that of the chaotic hadrons) in the GGL formula. Using empirical formulae for the par…
The $2S$ $B_c$ states observed by ATLAS, CMS and LHCb Collaborations are discussed. The observation perspectives of $B_c^*$, $2P$ wave, $3P$ wave and $D$ wave states of $B_c$ at LHC experiments are estimated.
In hadronic Z decays, we compare Bose-Einstein correlations in \Pgpz pairs with those in identical charged pion pairs. We also measure Bose-Einstein correlations in triplets of identical charged pions. From the first study, the source radius is found to be smaller for \Pgpz-\Pgpz than for \Pgppm-\Pgppm, as would be expected, e.g., in a string model. However, the second study shows that the data are consistent with the pion production being completely incoherent. Both studies use data collected by the L3 collaboration at LEP.
Simultaneous Buda-Lund hydro model fits are presented to identified particle spectra and two-particle Bose-Einstein correlations as measured by the STAR collaboration in $\sqrt{s}=200$ GeV p+p collisions at RHIC. Preliminary results are compared to similar results in Au+Au collisions at RHIC, hadron+p reactions as well as Pb+Pb collisions at CERN SPS.
Recently, LHCb Collaboration announced the discovery of radial excitations of $D_s$ and $B_s$ mesons. In present work, we calculate the most promising strong and electromagnetic decay widths of radially excited $D_s(2S)$ and $B_s(2S)$ mesons within the light cone QCD sum rules method.
Recently DELPHI Collaboration reported new data on Bose-Einstein correlations (BEC) measured in e+e- -> W^+W^- events. Apparently no enhancement has been observed. We have analyzed these data including final state interactions (FSI) of both Coulomb and strong (s-wave) origin and found that there is enhancement in BEC but it is overshadowed by the FSI which are extremely important for those events. We have found the following values for the size of the interaction range beta and the degree of coherence lambda: beta=0.87 +/- 0.31fm and lambda=1.19 +/- 0.48, respectively.
Double parton scattering (DPS) is studied at the example of $J/ψ$ pair-production in the LHCb and ATLAS experiments of the Large Hadron Collider (LHC) at centre-of-mass energies of $\sqrt{S}=$ 7, 8, and 13 TeV. We report theoretical predictions delivered to the LHCb and ATLAS collaborations adjusted for the fiducial volumes of the corresponding measurements during Run I and provide new predictions at 13 TeV collision energy. It is shown that DPS can lead to noticeable contributions in the distributions of longitudinal variables of the di-$J/ψ$ system, especially at 13 TeV. The increased DPS ra…
In order to include a correction by the Coulomb interaction in Bose-Einstein correlations (BEC), the wave function for the Coulomb scattering were introduced in the quantum optical approach to BEC in the previous work. If we formulate the amplitude written by Coulomb wave functions according to the diagram for BEC in the plane wave formulation, the formula for $3π^-$BEC becomes simpler than that of our previous work. We re-analyze the raw data of $3π^-$BEC by NA44 and STAR Collaborations by this formula. Results are compared with the previous ones.
Inspired by the observation of the doubly charmed tetraquark state $T_{cc}^+$ at the LHCb Collaboration, we systematically study the $S$-wave interactions between a pair of charmed mesons ($D_{1},\,D_{2}^{\ast}$) in the $T$-doublet, where we adopt the one-boson-exchange model and consider both the $S$-$D$ wave mixing and coupled channel effects. Our numerical results suggest that the prime doubly charmed molecular tetraquark candidates are the $S$-wave $D_1D_1$ state with $I(J^P)=0(1^+)$, the $S$-wave $D_1{D}_2^{\ast}$ states with $I(J^P)=0(1^+,\,2^+,\,3^+)$, and the $S$-wave ${D}_2^{\ast}{D}_…
In order to analyze data on charged pions correlation channels, pi^+(2pi^-) and pi^-(2pi^+), we propose new interferometry approach using the Coulomb wave function. We show that to describe adequately data we have to introduce new parameter describing the contribution of pi^-(k_1) pi^+(k_2) --> pi^-(k_2) pi^+(k_1) process. Using this new formula we analyze data on pi^+(2pi^-) and pi^-(2pi^+) channels at sqrt(s) = 91 GeV by DELPHI Collaboration, and estimate the magnitude of this new parameter as well as the degree of coherence.
